P.1 

OAR Box 1126 

Prepped by Ollie Stewart 

Document Number: 

36)11-1-158 

Docket Number: 

A-83-22 

Printed 4/18/2008 9:58:22 AM Sheet 36 of 182 
P.2 

•>|ffc> 

#~£3 ^ ncrzCHAPTER 

TRANSPORT AND DISTRIBUTION IN A WATERSHED 

ECOSYSTEM 

L. L. Getz 

Department of Ecology, Ethology, and Evolution 

University of Illinois 

G. L. Rolfe 

Department of Forestry 

University of Illinois 

tf •» h 

J*Vten* 

A. W. Haney 

Department of Botany 

University of Illinois 

R. W. Larimore and J. W. McNumey 

Illinois State Natural History Survey 

H. V. Leiand 

U.S. Geological Survey 

P. W. Price 

Department of Entomology 

University of Illinois 

R. L. Wortman 

Department of Civil Engineering 

University of Connecticut 

J. L. Hudson 

Department of Chemical Engineering 

University of Virginia 

R. L. Solomon and K. A. Reinbold 

Institute for Environmental Studies 

University of Illinois 

^s,r. 

ft 

> 

ts. 

INTRODUCTION 

Watersheds are discrete units that provide a logical base for input-output studies. A major advantage 

is that streamflow, along with dissolved and suspended matter, is routed through a single exit. Thus 

monitoring for substances that have either soil or 

water as major sinks is greatly simplified. Because of 

these advantages, an 86 mi2 watershed was chosen 

by the University of Illinois for lead transport and 

distribution studies, (fig. 6-1) The predominantly agricultural watershed lies primarily to the north of 

Champaign-Urbana; however, it includes about 90 

percent of the metropolitan area with approximately 

100,000 inhabitants. 

The rural portion of the watershed is drained by 

the Saline Branch of the Vermillion River, and the 

urban portion by the Boneyard Creek. The streams 

join on the east edge of Urbana and flow from the 

system to the east. The major crops are corn and 

soybeans. Woodlands, pasture, and wasteland (such 

as railroad rights-of-way and stream margins) are 

also included in the watershed area. 

The objectives of the study included (1) characterizing the input, accumulation, and output of lead 

from automobile sources in a typical midwestern 

ecosystem; 2) understanding the mechanisms controlling fluxes between system components: and (3) 

•-Sampling Stations 

FIGURE 6-1.—Map of Saline Branch Watershed. 

• i , 

105 

i iri 
evaluating potential effects of lead on ecosystem 

components other than man. This discussion emphasizes the first objective. 

An ecosystem distribution model was developed 

[1] to identify ecosystem components for intensive. 

study and to provide a frame of reference for tr?4* * 

numerous investigators. A diagrammatical repres£iis*«*w 

tation of the model is shown in figure 6-2. The model includes major components of both the aquatic 

and terrestrial ecosystems; it represents the system 

by a network of nodes and branches, where the 

nodes represent the components of the ecosystem in 

a general sense, and the branches indicate possible 

transport mechanisms between nodes. 

Source nodes in the model such as auto emissions 

only have lead exiting, while sink nodes (outflow 

water) only have branches entering. Three attributes 

are associated with each node: a mass, a quantity of 

lead input per unit time for source nodes, and the 

initial concentration in the node. 

Branches represent a variety of transport mechanisms such as diffusion, leaching, biological uptake, 

and erosion. Self-loops represent the fraction of lead 

content of a node that remains in that node between 

time periods. Distribution factors and seasonal factors are used to quantitatively describe the branch 

flows. The distribution specify the fraction of the 

lead content of a node that flows in the branches 

emanating from that node. These distribution factors 

can be constant or random variables that follow various probability distributions based on the characteristics of the flux in question. Transports may also be 

affected by the seasons of the year. This is accounted for by modifying the distribution factor of each 

branch by an appropriate seasonal factor. 

The current network for the model contains over 

40 nodes and 130 branches to accomodate zoning of 

M*S*B- TM"NDA 

FIGURE 6-2.—Basic ecosystem model. 

, ,;] r . 

the system into a'»range of lead inputs based on 

traffic volume. Nodes such as primary producer&aS^ 

defined generally in this models but more detailed 

study of these compartments by species or family 

can easily be included. 

; Initial runs of the model provided a sense of 

^direction fpr.:tffef

rsjtudies in terms of identifying critical geographical areas of the watershed and ecosystem 

;components. The runs also provided individual investigators with an understanding of how their studies 

and results would fit into the ultimate ecosystem / 

analysis. _ 

SYSTEM INPUTS 

Gasoline consumption represents the major source 

of lead input to the watershed. To determine the 

effects of lead, the magnitude and distribution of the 

metal from traffic sources, as well as the spatial and 

temporal variations of this input, must be determined. Ideally, the amount and distribution of lead 

emitted to the atmosphere from each automobile in 

the watershed should be examined, but this would 

be an impossible task. Rather than sampling emissions, lead input was estimated by relating emissions 

tp gasoline consumption patterns. The gasoline consumption of automobiles has been documented by 

numerous studies. With these data, if vehicular travel information is available, an estimate of the magnitude can be derived, as well as the spatial and temporal consumption of gasoline for a particular area. 

Traffic and transportation engineers have developed techniques for sampling and estimating vehicle 

travel for use in traffic planning and operations studies. Basically, these involve determining traffic volume on each segment of streets and highways. The 

traffic volume data and information on street networks can be used to estimate vehicle miles of travel. This was the only feasible method of estimating 

lead emissions fpr the watershed area. 

Sales data might appear tp be an pbvipus source 

of gasoline consumption information. However, 

there is no assurance that the fuel is consumed in 

the locale where it is sold. For example, gasoline 

purchased at a location on an interstate highway 

would not likely be consumed in the immediate area. 

Sales information has been utilized in this study, but 

primarily to check the accuracy of estimates obtained from travel information. 

Methods used in the current watershed study are 

as follows. First, the various streets and roads were 

classified into groups by traffic volume. This classification permitted a rapid examination of the system 

by looking at those streets and roads that are responsible for most of the lead entering the ecosystem. 

Both the rural roads and urban streets were categorized into five classifications by average daily 

traffic (ADT) volumes. The specificatipns pf each 

class, as well as the tptal miles pf road in each, are 

summarized fpr rural roads (table 6-1) and urban 

streets, (table 6-2) 

106 
tl*'' 

P.4 

TABLE 6-4. -Gasoline consumption within compartments 

*-, 

Ir 

'*'* 

Class 

Class I* 

Class II 

Class III 

Class IV 

Class V 

oy average aauy trajjtc volume {/ 

ADT 

over 4,000 

2,000 to 3,999 

1,000 to 1,999 

250 to 999 

under 250 

IUI} 

Total miles 

n.6 5 

0.0 

6.2 

15.1 

64.1 

Compartment 

Rural 

Rural subcompartment 

Urban 

Urban subcompartment 

Total daily 

vehicle miles 

164,318 

1,491 

575,643 

262,628 

GasC 

Total daily 

onsumption (gal.) 

10,524 

86.5 

46,051 

21,010 

In the second method used in the study, traffic 

data were analyzed to provide estimates of vehicle 

miles of travel and, eventually, gasoline consumption. This analysis yielded a spatial distribution of 

gasoline consumption and, therefore, lead output. 

Table 6-3 shows the rates of gasoline consumption 

that were obtained from auto manufacturers to be 

used in the analysis. Gasoline consumption for the 

various compartments is summarized in tables 6-3 

and 6-4. 

TABLE 6-2.-Classification of urban streets 

by average daily traffic volume (ADT) 

Class 

Class I 

Class II 

Class III 

Class IV . 

Class V 

ADT 

over 10,000 

5,000 to 10,000 

2,500 to 4,999 

1,000 to 2,499 

under 1,000 

Total miles 

16.90 

20.00 

15.83 

20.20 

70.40 

Gasoline consumption by roadway classification is 

shown in table 6-5 and includes total daily vehicle 

miles, gallons of gasoline consumed, and the percentage of total gasoline consumption in each street or 

road class. Note that class I, class II, and Interstate 

74 make up 76 percent of all gasoline consumption 

for the urban streets, while class I makes up 89 percent of the gasoline consumption for the rural roads. 

In summary, then, the gasoline consumption for 

the watershed is: 

Urban 46,051 + 2,700 gal./day 

Rural 10,524 + 560 gal./day 

Total 56,575 + 2,940 gal./day 

' Gasoline consumption was also compared between 

a rural subcompartment and an urban subcompartTABLE 6-3. - Gasoline consumption as a function of speed 

and classification of streets and roads in the watershed 

based on average Speeds1 

Road type Speed (mph) Gas Consumption (mi/gal.) 

Local rural 

Route 45 

Interstate 57, 74 

Local urban 

35 

60 

70 

30 

16.7 

16 

15 

12.5 

ment. The 5.1 mi2 rural subcompartment is in the 

northwest corner of the rural compartment and has 

9.4 mi of roads. The urban subcompartment, an area 

of 4.0 mi2 in Champaign, has 68.1 mi of streets. 

Gasoline consumption is about 250 times greater in 

the urban than in the rural section. 

In converting gasoline consumption data to lead 

emissions in the ecpsystem, the following assumptions were made: 

(1) Gasoline contains 2.5 g of lead per gal. 

(2) In urban areas, due to the nature of the traffic 

flow, 50 percent of the consumed lead is considered to be emitted from the exhaust system 

of the automobile. 

(3) In rural areas with generally higher vehicle 

speeds, 80 percent of the consumed lead is 

emitted. 

Total lead input to the watershed on a yearly basis 

is shown in figure 6-3. The 12 mi2 urban compartment receives approximately 75 percent of the total 

lead input, while the 74 mi2 rural area receives only 

25 percent. These emission data, on a per-vehicle 

volume basis, are 0.101 g lead per vehicle mile for 

the urban compartment and 0.128 g for the rural 

compartment. These figures compare favorably with 

the average lead emission rate for production vehicles of 0.108 g/mi. [2] On the basis of Cantwell's 

figure, if 0.50 g or 46 percent remains airborne, the 

total lead input to the ecosystem, with the exception 

of air, is reduced to 16,000 kg/year. The majority of 

this deposition occurs in the urban area (10,400 kg) 

and along major highways (3,900 kg). 

If the ecosystem is divided into zones based on 

traffic volume, the relative concentration factors for 

lead inputs to each zone can be determined, (table 6-

6) Zone 1 is a 50 m strip of land on both sides of 

highways with traffic volumes greater than 4,000 

vehicles/24 h; zone II is the same width strip along 

TABLE 6-5. -Gasoline consumption per day 

determined by roadway classification 

1

 Based on data from automobile manufacturers. 

Class 

Class I 

Class II-V 

Class I 

Class II 

Class III 

Class IV 

Class V 

1-74 

North of 1-74 

Vehicle miles Gallons 

Rural roads 

144,505 

19,813 

9,335 

1,189.4 

Percent of total gallons 

Urban roads (not including 1-74) 

212,390 

141,685 

56.083 

31,545 

33,968 

80,590 

13,982 

16,991 

11,335 

4,487 

2,524 

2,717 

6,447 

1,119 

. 

89 

11 

37 

25.5 

10 

5 

6 

14 

2 

107 

246-867 O - ft - 8 
P.5 

TABLE 6-6.-Relative concentrations of lead by zones 

Zone Vehicles Percent total area Relative concentration1 

I 

II 

III 

rv 

>4,000 

1,000-2,000 

Rural, Remote 

Urban 

8.5 

17 

59.5 

15 

70 

14 

1 

140 

1

 The value of 1 is assigned to the rural, remote area. 

highways with traffic volumes less than 4,000 vehicies/24 h; zone III represents rural areas remote 

from highways; and zone IV is the urban area. The 

relative concentration factors for zones I and IV are 

very high and indicate areas of concern due to the 

tremendous lead input per unit area. 

The input to the ecosystem of lead in rainwater 

has also been monitored, and representative data for 

the urban and rural compartments are shown in figure 6-4. Rainfall input averages 2 percent of the total 

from automobile emissions. Collections were made 

by placing 48 acid-washed polyethylene bottles at 

random locations within the watershed tP cpllect 

samples during each stprm period. The bottles were 

placed prior to the rainfall and collected afterwards 

to avoid dustfall contamination. Total rainfall was 

monitored by recording rain gages. 

SYSTEM OUTPUTS 

Surface drainage discharge was monitored continuously at five gaging stations located on the Saline 

Branch of the Vermillion River and Boneyard 

Creek.(fig. 6-5) The gage locations allow a compari30000 r 

25000 

/YEAR AMS KILOGR 

l -

- > INP 

Q 

< 

20000 

15000 

10000 

5000 

URBAN 

RURAL 

URBAN 

RURAL 

FIGURE 6-3.—Total lead input from automobile emission to 

the urban and rural compartments. 

rr 

< 

UJ 

>-

tn 

< 

e> 

o 

rQ. 

Q 

< 

LU 

1000 

750 

500 

250 

URBAN * J 

FIGURE 6-4.—Lead input to rural and urban compartments ot 

the watershed from precipitation. 

son of the water volume and lead output from the 

rural portion of the watershed with those from the 

urban area. This same kind of comparlspn can be 

made between a small rural agricultural watershed pf 

approximately 4 mi2 and a tPtally urban watershed 

pf similar size, pr between the entire rural and urban 

cpmpartments. An additipnal gaging statipn, located 

5 mi dpwnstream from the watershed, provides an 

estimate pf stream recpvery due tp dilutipn effects 

pf rural drainage waters. • 

RURAL 

COMPARTMENT 

^ 

•i 

:

4 

» SALINE BRANCH ADDITIONAL « 

URBAN 

COMPARTMENT 

CHAMPAIGN;- URBANA 

mm: 

COMPARTMENT 

• LANDFILL 

SEWAGE TRT. PUNT 

•STREAM GAGING STATION 

FIGURE 6-5.—Schematic diagram of idealized Saline Branch 

watershed. 

108 

m m 
P.6 

w 

w. 

$; 

v

' 

V 

* 

' 

^ 

^ 

tr. 

< 

UJ 

>-

\ 

tn 

2 

< 

tr 

o 

o 

_J 

* : 

<o 

h-

•D 

Q_ 

H 

3 

O 

Q 

< 

LU 

_J 

,*f> 

(' *, •* 

looor 

750 -

500 

250 -

FIGURE 6-6.—Total lead output in streamwater from urban 

and rural compartments. 

Total water volume moving past each gage was 

determined for each 24 h period. Water samples 

were taken at 15 min. intervals and composited for 

each 24 h period at each location by continuousduty, compositing samplers. During storms, a separate automatic water sampler collected individual 1-1 

samples at shorter time intervals proportional to the 

height of the stream. 

Water samples were filtered through a 0.45 /xm 

Millipore filter. The filtrate was analyzed by anodic 

stripping voltammetry, and the suspended solids by 

atomic absorption spectroscopy. Lead concentrations varied widely, ranging from 0 to 15 ^g/1 in filtrate and from 15 to 200 jug/1 in the suspended solids. 

The total output of lead on a yearly basis for the 

urban and rural compartments is shown in figure 6-6. 

The 600 kg annual output for the urban compartment is approximately 75 percent of the watershed 

total. Output from the rural compartment totals 210 

kg. A comparison between the total output (fig. 6-6) 

and the total input (fig. 6-2) indicates that only approximately 2 percent of the total input exits via 

3 

Q. 

r> 

o 

Q 

< 

UJ 

z 

Ul 

<_> 

cr 

UJ 

a. 

100 r 

75 -

50 

25 -

1 1""'Y-''Vv""'/ ^T-J&fr 

-SUSPENDED f 

-;. SOLIDS r 

URBAN 

*J-0! -, 

&'# • 

*>j "V 

SUSPENDED 

SOLIDS 

V' 

'HH3i£SIl 

RURAL 

FIGURE 6-7.—Lead distribution between filtrate and suspended solids in urban and rural compartments. 

streamwater, leaving a considerable accumulation of 

lead in other components of the system. 

In considering lead in streamwater, it is important 

to evaluate its distribution in the filtrate and suspended solids. This is shown in figure 6-7 for both 

urban and rural compartments. As would be expected, most of the lead is associated with suspended 

solids, with very little dissolved in the filtrate. The 

ratio of lead in suspended solids to that in filtrates 

varies from 4:1 in the rural compartment to 27:1 in 

the urban compartment. The large amount of lead 

associated with suspended solids in the urban compartment undoubtedly was related to the vast areas 

of impervious surfaces from which particles are 

quickly washed away during rainfall. 

A comparison of total lead output during selected 

storm periods, based on the normal 24 h composite 

samples and the individual 5 min. samples, is shown 

in table 6-7. The composite sampler underestimated 

lead output by an average of 30 percent. However, 

there were no significant differences in sampling system estimates during periods of nonstorm flows. 

In 1974 lead output from the urban compartment 

based on data from 5 min samples from selected 

storm periods and days without precipitation, 

amounted to 910 kg, as compared with 600 kg based 

on composite sampling. Thus the output is 7.5 percent of the estimated 10,400 kg urban input, indicating a large annual storage of lead in the urban ecosystem. 

'J&-J*. 

4 

Storm date 

4/11/74 

4/29/74 

5/28/74 

6/7/74 

7/8/74 

8/2/74 

TABLE 6-7. 

Total 

-Total lead output from the urban subcompartment 

for several selected storms 

precipitation Discharge 

(in.) 

0.17 

0.28 

0.14 

0.22 

0.18 

0.90 

(ft3) 

30 x 104 

40xl0 4 

26xl0 4 

63 x 10" 

80 x 104 

22xl0 5 

during 1974 

Lead output, 

5 min. 

estimate (kg) 

2.57 

3.41 

2.11 

8.31 

7.96 

8.75 

Lead output, 

composite 

estimate (kg) 

1.96 

2.34 

1.80 

5.25 

5.98 

5.69 

w 109 
P.7 

LEAD IN THE TERRESTRIAL ECOSYSTEM 

Air 

A number of investigations have been made of 

atmospheric lead concentrations. [3-8] Most of the 

studies were conducted in urban areas with high 

traffic densities .and characterized the air quality of 

an entire city by using only a few sampling sites (at 

the most six or eight and often only two or three). 

In some cases, studies covered only 1 or 2 days. Air 

sampling equipment was often located well above 

ground level, and many times residential air quality 

was not well differentiated from that of the central 

city. 

The air monitoring program for the ecosystem 

study encompassed studies of the distribution of 

ambient atmospheric lead concentrations in the rural 

and urban compartments, as well as sample areas 

with varying traffic densities. This provided an accurate picture of the ecosystem's airborne lead. 

Field measurements were obtained with General 

Metal Works' high-volume samplers. To ensure the 

most effective use of the samplers, an analytical 

model was used to predict the distribution of airborne lead concentrations. The samplers were then 

placed where they would most effectively test the 

model. Figures 6-8 and 6-9 indicate the locations of 

the samplers with a letter assigned to each location. 

Figure 6-8 also shows mean air lead concentrations 

for the study period. 

The samplers were powered by existing electrical 

outlets or propane-fueled electrical generators at 

remote locations. Initially, Gelman 8 in. by 10 in., 

GA-1 Metricel triacetate filters (5 yum ppre size) were 

used as primary filters, with standard 8 in. by 10 in. 

Type A fiber glass filters (0.8 jum pore size) as secondary filters. Both filters were analyzed for lead 

content. The single 8 in. by 10 in. fiber glass filter 

gave results equivalent to those pbtained using the 

dual arrangement and was used in subsequent tests. 

After cpmpletipn pf a 24 h run (nprmal procedure), 

the filter was cut intp eight sectipns, and three randpm sectipns were analyzed fpr lead by atpmic absprptipn spectrpscppy. 

Rural: From August, 1973 tp February, 1974, 11 

sampling locations were established throughput the 

watershed, (fig. 6-8) with eight in the rural and three 

in the urban cpmpartment. During this period, the 

rural atmospheric concentrations were intensively 

sampled, and preliminary information was obtained 

on urban concentrations. Background levels were 

assumed to be 88 percent of the measured rural concentrations. [9] In all, 152 measurements were made 

on 30 different days. Averages over the sampling 

days appear in figure 6-8 next to each sampling location. 

Lead concentrations did not vary greatly within 

the rural compartment. Lead concentration at remote stations E and I averaged about 0.19 Mg/m3

. 

However, at stations nearer the urban area but still 

in the rural compartment, the average was about 

0.25>ug/m3. 

Urban: Although airborne lead samples were taken 

at three urban stations (D, H, and K) during the'intensive rural sampling period, the intensive sampling 

network for the urban compartment was not established until February, 1974. From May to July, 1974, 

all 19 samplers were in operation, while two additional sampling stations (C and J) continued to operate in the rural compartment, (fig. 6-9) 

The urban compartment was divided into four 

areas based on use: residential, downtown, university, and suburban-commercial. Nine samplers were in 

operation in the residential area. Samplers D, L, M, 

Y, and AA were located on lawns next to streets 

with traffic volumes less than 1,000 ADT; sites U, 

V, W, and X were on lawns along main residential 

streets, with volumes of 4,000 to 5,000 ADT. The 

downtown areas had three samplers on streets with 

12,000 to 20,000 ADT, with one of the samplers (Q) 

oh the roof of a two-story building. Six samplers 

were placed on streets around the university with 

greatly varying volumes (2,000 to 20,000 ADT). Station K consisted of a ground-level sampler (Ki) and 

another sampler (K") directly above on the roof of a 

four-story building. Station N had one sampler (Ni) 

17 ft from a high-volume street (20,000 ADT) and 

another (N?) 29 ft from the same street. The suburban-commercial area had only one sampling station 

(H), which was in a light industrial park near the 

intersection of Interstate highways 57 and 74. 

Airborne lead concentrations for each sampling 

station and traffic volumes of the urban compartment are summarized in table 6-8 for the 3 month 

sampling period, May through July, 1974. The relative magnitude airborne lead concentrations are in 

agreement with traffic levels at each station. At station K, the roof-top sampler (K2) had 40 percent 

lower concentrations than the ground-level sampler 

(Ki). This supports the assumption of uniform vertical mixing of pollutants, which is often used in urban "box" models. Measurements from station N 

indicated a transverse decrease of 14 percent in airborne lead concentrations when the sampling distance was increased from 17 to 29 ft. 

Table 6-9 summarizes airborne lead concentrations 

for ground-level stations at each of the four urban 

areas along with concurrent rural concentrations. 

In conclusion, as shown in tables 6-8 and 6-9, airborne lead concentrations are generally low in the 

rural and residential areas, while much higher values 

have been measured in the urban areas with a peak 

of 3.8A«g/m3. 

Soils and Plants 

The presence of lead in plants, often in concentrations approaching a hazardous level, is well documented in the literature. Numerous investigations 

have shown that the concentration of lead in soils 

and plants is significantly higher near highways and 

drops rapidly along gradients away from this source. 

[10-16] Although wind direction, speed, and turbulence are important factors in determining the steepness of these lead gradients, Suchdoller [13] report110 
P.8 _ 

= ^ 1 

o 

North 

Mean Lead Concentration 

August,, 1973 - February, 1974 

.l73/ug/m3 

+ 

E 

0 1 2 

Miles 

Major Roads 

FIGURE 6-8.—Average air lead concentrations in ecosystem. 

FIGURE 6-9.—Location of urban air samplers in ecosystem. 

"fc 111 
P.9 

TABLE 6-8.-Average urban airborne lead concentrations, 

May-July, 1974 

Site (station) 

Downtown 

Q (root) 

T 

Z 

University 

0 

P 

K, (ground) 

k3 (roof) 

N, (17 ft) 

N, (29 ft) 

Residential 

U 

V 

W 

X 

D 

L 

M 

y 

AA 

Suburban commercial 

H 

1

 Difficult to estimate. 

ADT 

12-20,000 (class I) 

12-20,000 (class 1) 

12-20,000 (class 1) 

15,000 (class 1) 

7,000 (class II) 

2,000 (class IV) 

20,000 (class 1) 

(') 

5,000 (class III) 

5,000 (class III) 

4,000 (class III) 

250 (class V) 

700 (class V) 

800 (class V) 

800 (class V) 

500 (class V) 

(') 

2

 Not close to a specific street. 

Airborne lead 

(Mg/m3) 

0.767 

1.445 

1.263 

0.569 

0.631 

0.425 

0.306 

1.548 

1.345 

0.357 

0.342 

0.332 

0.306 

0.242 

0.250 

0.269 

0.284 

0.183 

0.244 

ed that the gradient may be diminished completely 

within 30 to 40 m of a highway. Motto et al. [11] 

reported that the lead content of soils and plants 

sampled along heavily traveled highways increased 

with traffic volume. They also reported that the major effect of traffic was limited to the surface soil in 

a narrow zone within 30 m of the road. 

Studies of lead in plants and soils were initiated in 

the summer of 1970 within initial focus on six plant 

species (including corn, soybeans, bluegrass, clover, 

dandelions, and fleabane) and the associated soil in 

transects away from a major highway (approximately 12,000 vehicles per 24 h). [17] In nearly all species 

tested, lead in or on tissues was a function both of 

distance from the road and lead in the soil. Analyses 

of variance were run to determine differences in lead 

content of taxa and lifeforms (i.e., annual or perennial). No significant differences were found in root 

lead but the lifeform-family interaction was significant for lead in washed foliage. Table 6-10 shows 

the interpretation of the significant interaction. 

TABLE 6-9. -A verage airborne lead concentrations, 

ground level stations, 

May-July, 1974 

Area 

Airborne lead 

(Mg/m3)' 

Downtown 

University 

Residential 

Suburban commercial 

Rural 

1.352 

0.747 

0.287 

0.254 

0.170 

TABLE 6-10. -Analysis of significant lifeform-family interaction 

of lead in washed foliage by using Tukey 's W-procedure at P < 0.051 

Soybeans Dandelion Bluegrass Fleabane Sweetclover Corn 

11.4 9.6 8.6 6.8 6.0 6.0 

1

 Values are mean lead levels as Mg/g dry-weight basis. 

A common underline indicates no significant difference. 

These data suggest that some plant species accumulated more lead than others, and that the accumulation rate was not influenced by whether the species 

was an annual or perennial. The correlation between 

distance from the highway and soil lead was significant (P =s 0.001) up to 50 m for the 0 to 10 cm samples. The correlation between the surface soil lead 

content (0 to 10 cm) and the subsurface soil lead 

content (10 to 20 cm) was also significant (P =s 

0.001). 

Soils in the rural area of the watershed were sampled intensively to further investigate the relationship between traffic volume, distance, and direction 

from highways. Traffic volume estimates were used 

i to classify roads. Sampling was done in transects to 

100 to 200 m from road pavements, with only the 

surface soils (0 to 10 cm) examined, (fig. 6-TO) Each 

1400 

1200-

1000-

100-

E 

Q. 

Q. 

TJ 

O 

a> 

8 0 -

o 

tn 6 0 -

40 

2 0 -

i . - T 1—-r 

-

-

i 

* 

1 i 1 

Low Traffic Volume 

~ (Thomasboro Road) 

\ / / 

/ 

• 

i.i. l 

• 

1. 

ll ll 

OL. 

rr 

1 1 

1 j 

1 1 

1 1 

1 1 

1 1 

1 1 

1 1 

1 1 

1 

1 V 

1 

1 

1 / / / / 

' 

1 ' 1 ' I 

High Traffic Volume 

(U.S: 45 North) 

1. 

\ \ \ \ \ \ 

1 i 1 i L 

. -

-

/ V 

—, 'l'l | 

-

IOO 60 20 0 20 60 

Distance from Highway (meters) 

100 

1 

FIGURE 6-10.—Soil lead in relationship to distance from highway. 

112 
P.10 

I t 

4. 

« • • 

*&" 

IT.' 

•#rsample was a composite of six soil probes to a depth 

of 10 cm, taken at 5 m intervals along the transect. 

Figure 6-10 represents a composite of 12 transects 

from high-traffic highways and 12 transects from 

low-traffic highways; it illustrates the rapid decrease 

in lead concentration to background. The highest 

levels were found immediately adjacent to pavements of roads with the highest traffic volumes. On 

the downwind side (east) of north-south roads, the 

lead content of soils decreased to background levels 

within 50 m. On the upwind side, levels immediately 

adjacent to the pavement were comparable to those 

on the downwind side, but decreased more rapidly 

away from the road, reaching background levels 

within 20 m. Roads with low traffic volumes (less 

than 2,000 vehicles per 24 h) had associated soil lead 

gradients to background levels within no more than 

5 to 10 m of the pavements on both the upwind and 

downwind sides. Thus soil lead was seldom influenced beyond the right-of-way of roads with less 

than 2,000 vehicles per 24 h. East-west roads with 

high traffic volumes had soil lead gradients that were 

essentially comparable on the north and south sides 

and intermediate to the east and west gradients on 

north-south roads. Lead in soil nearest the pavements was much the same as for the north-south 

roads, but the lead gradient decreased to background 

within 30 m of the pavement. 

The results indicate that the higher the traffic volume, the higher the soil lead content, and the farther 

the lead gradient extends from the highway. Even 

on the most heavily traveled roads, the strong enhancement of soil lead extended only 50 to 75 m 

downwind and 25 to 40 m upwind. Extremely high 

, lead levels (>. 50 Mg/g) were seldom found in this 

study beyond 20 m from pavements, except in unusual circumstances such as ditches draining road 

surfaces. 

Lead accumulation in urban and rural soil profiles 

is shown in figure 6-11. The concentrations are averages of 10 profiles. The urban profiles were taken 

within 10 m of a city street (12,000 vehicles per 24 

h). Figure 6-12 shows an urban profile sampled within 1 m of a heavily traveled city street (15,000 to 

17,000 vehicles per 24 h), with a breakdown of the 

top 3 cm into 1 cm segments. The rural profiles were 

taken in an agricultural field remote from a highway. 

Maximum concentrations were found in the upper 10 

cm, with a sharp decline in concentration between 

10 and 20 cm. Below 20 to 30 cm, the lead concentration was relatively uniform. Considerably higher 

concentrations were evident in the urban profiles, 

which again showed a strong correlation with traffic 

volume. 

" Intensive studies of lead in the vegetation of the 

ecosystem, during the summers of 1971-74 showed a 

similar influence of the proximity and direction from 

highways as that observed for soils. Sampling was 

completed when the plants were fully mature in the 

field. Along the heaviest traveled roads (12,000+ 

vehicles per 24 h), there was significantly more lead 

in or on corn and soybeans within 20 m of the pavement; by 30 m from the pavement, however, lead in 

URBAN RURAL 

o-io 

10-20 

20-3 0 

30-4 0 

40-8 0 

CM 

CM 

CM 

CM 

CM 

390 

165 

48 

4 0 

19 

PPM 

PPM 

PPM 

PPM 

PPM 

16 

9 

7 

6 

4 

PPM 

PPM 

PPM 

PPM 

PPM 

FIGURE 6-11.—Lead concentrations in urban and rural soil 

profiles. (Values shown are the mean of 10 profiles in each 

location.) 

Or on crops was not different from the average for 

the field. On lesser traveled roads, there was no 

observable influence of the highway on crop lead. 

Along the heavily traveled roads, corn and soybeans 

growing within 20 m of the pavement averaged 

about 30 Mg/g lead, whereas plants farther away 

from the pavement and along secondary roads averaged 8 Mg/g- Analyses of kernels of corn and soybeans showed a consistently low lead content, averaging less than 2 Mg/g. Figure 6-13 shows a composite of 12 transects from high traffic highways and illustrates the influence of traffic on lead in vegetation 

and soils. 

(I0,200ppm)0-lcm v 

( 6,400ppm) I -2cm -

( l,400ppm)2-3cm'^r: 

0-I0cm(l,l40ppm) 

>IO-20cm(l80ppm) 

•20-30cm(49ppm) 

>30-40cm(39ppm) 

FIGURE 6-12.—Urban soil profile with top three 1 cm segments analyzed individually. 

113 
P.11 

1200 

1000 

800 

e 

Q. Q. 

"§60 0 

_l 

</)400 

200 -

Soil Lead 

Plant Lead 

Lead content in the vegetation of the ecosystem is 

summarized in table 6-11. The size (223 km2) and 

diversity of the watershed precluded a routine approach to sampling. Consequently, the watershed 

was divided into rural and urban compartments. The 

rural compartment was subdivided into vegetation 

habitats. A description of the divisions is given below: 

A. Urban: All areas within the watershed developed 

for residential or industrial use. 

1. Pervious: All npnpaved surfaces. 

2. Impervious: All paved surfaces, including 

roofs. 

B. Rural: 

60 20 0 20 60 

Distance from Highway (meters) 

FIGURE 6-13.—Soil and plant lead as related to distance from 

highway. 

1. Fields 

a. Cultivated fields: All crop fields that 

were tilled within the last year. 

b. Sod fields: All crop fields and/or pastures that are tillable. 

2. Roads (See section on traffic sampling.) 

a. Pavement. 

b. Roadsides: Up to and including bordering fencerows. 

3. Railroads 

a. Track pavement. 

TABLE 6-11. -Summary of lead content of vegetation and habitat areas in a Champaign County watershed 

Habitat 

Total 

area (kma) 

Percent of 

watershed 

\ Average Pb Content 

; of vegetation 

I (Mg/g) 

Average dry biomass 

of vegetation 

(g/m2) 

Total Pb in 

vegetation of 

habitats (g) 

A. Urban 

1. Pervious 

2. Impervious 

B. Rural 

1. Fields 

a. Cultivated 

b. Sod 

2. Roads 

a. Class I 

Pavement 

Roadside 

b. Class II 

Pavement 

Roadside 

c. Class III 

Pavement 

Roadside 

d. Class IV 

Pavement 

Roadside 

e. Class V 

Pavement 

Roadside 

3. Railroad 

a. Track pavement 

b. Right-of-way 

4. Homestead 

5. Streams 

6. Fencerows 

7. Waste areas 

8. Woods 

9. Pond (surface water) 

Total 

14.5 

17.2 

166.4 

3.8 

0.8 

1.6 

0.1 

0.1 

0.1 

0.2 

0.1 

0.3 

1.1 

2.2 

0.5 

0.5 

5.9 

3.1 

3.0 

3.0 

1.5 

0.3 

226.2 

or 

(87.3 mia) 

6.4 

7.6 

74.6 

1.7 

0.3 

0.7 

0.1 

0.1 

0.1 

0.1 

0.1 

0.1 

0.5 

0.9 

0.2 

0.2 

2.7 

1.4 

1.3 

1.3 

0.7 

0.1 

67 

8.0 

4.1 

34.0 

21.0 

15.6 

9.0 

7.5 

6.7 

6.1 

4.7 

5.8 

6.5 

8.6 

287 

1,400 

800 

159 

155 

194 

278,820 

1,863,680 

124,640 

8,650 

326 

605 

288 

_ 

262 

520 

112 

623 

691 

664 

127 

— 

778 

4,323 

1,742 

4,031 

9,077 ' 

12,023 

12,948 

1,638 

— 

Total 2,211,105 

or 

2,211.1 kg 

V 

# • 

-

"' Kf 

.-

• x-

' f 

1

 Herb layer only. 

114 
P.12 

Tyt .< . . 

1 .;;.-

1 #o 

13c . ••• 

I1 •:* , -

i. 

4. 

5. 

, J 

1 j f 

W ' 

b. Right-of-way: Up to and including fencerows. 

Homesteads (See urban description). 

Streams: All vegetation bordering. streams 

that was not utilized for crops or pasture. 

In waste areas, this included only the 

stream bank vegetation. 

6. Fencerows: All unfilled areas between 

fields, whether a fence was present or not. 

7. Waste areas: Miscellaneous areas not identified in other categories. Included were 

refuse areas, dry borrow pits, permanently 

fallowed fields that lacked complete arborescent cover, rural cemeteries, and unused 

areas around isolated outbuildings. 

8. Woods: Forested areas with all or nearly all 

- arborescent cover. 

9. Ponds: Generally borrow pits. Surface water only was included. 

The total area for each compartment and subdivision was determined from aerial photographs. 

Ground checks were made in all cases where vegetation or land use was unclear. All compartments and 

subcompartments were randomly sampled with V\ 

m

2

 circular frames at peak standing crop. Transects 

were used to determine the lead content relative to 

distance and direction from roads, but, with the 

exceptions noted previously, traffic flow had little 

influence on the lead content. Because sampling was 

random within each subcompartment, the observed 

biomass (averaged) was multiplied by the total area 

to arrive at the total biomass. The average lead contentvof the vegetation in a subcompartment was then 

used to calculate total lead for a subcompartment. 

(table 6-11) 

An extensive sampling of urban vegetation and 

soils was completed in 1974. (table 6-11) In the transect studies, samples were taken at several locations 

within the urban area depending on traffic volume; 

the results show a similar pattern to the rural area. 

Somewhat different results were obtained on one 

particular set of four transects (street to house) on 

streets with low traffic volume (200 to 400 vehicles 

per 24 h) and four on streets with high traffic volume 

(12,000+ vehicles per 24 h), each of which was 

sampled at four different times during the year. (fig. 

6-14) The concentration of lead in both soils and 

plants along these transects, especially in the high 

traffic areas, increased as the houses were approached. These houses were all brick, unguttered 

but with painted trim. It is quite likely that lead particulates deposited on the roofs of these houses 

were washed off by rainfall and accumulated in soils 

and plants along the drip zone. However, a portion 

of this lead accumulation may be a result of leaching 

from paint on the house trim. 

Temporal distribution of lead is shown in figure 6-

15 from urban and rural tree-ring samples. The urban samples were collected from trees within 10 m 

of heavily traveled city streets (greater than 10,000 

vehicles per 24 h). The rural samples were from 

trees within 10 m of a country road (1,800 vehicles 

300 

200 

25 20 15 10 

Distance from Street (m) 

. Clark 

0°—Street 

-,2000-

1000 

20 15 10 5 

Distance from Street (m) 

Green 

Street 

(E-W) 

• Soils (0-IOcm) 

-Unwashed Plant Material 

FIGURE 6-14.—Soil and plant lead concentrations along transects from low (Clark Street) and high (Green Street) traffic 

volume city streets. 

per 24 h). The values are averages of 20 samples and 

show a significant increase between 50-year-old tree 

rings and current rings. This graphically illustrates 

the increased insult of lead to the environment during the past half century. [18] 

Urban Dust 

Two important points concerning the distribution 

of lead were discussed earlier in this chapter. First, 

an estimated 75 percent of the lead emitted from 

automobile exhausts was deposited in the urban 

compartment of the ecosystem. Second, the highest 

concentrations of lead in surface soils were within 

10 YEAR AVERAGE 

(1963 - 1973) 

7.9 PPM 

13.1 PPM 

Pb RURAL 

Pb URBAN 

10 YEAR AVERAGE 

(I9IO-I920) 

1.9. PPM Pb RURAL 

2.7 PPM Pb URBAN 

FIGURE 6-15.—Tree ring analysis of urban and rural trees. 

115 
P.13 

20 m or less of traffic thoroughfares. In urban areas, 

this means that a high percentage of the lead is deposited in, on, or around residences, commercial 

establishments, and other buildings. Further distribution and concentration are likely as lead associated 

with dust is blown around by the wind or tracked 

into buildings from streets, sidewalks, and other 

outside areas. Thus potential human exposure is 

much greater in urban than rural areas, and the total 

body burden is likely to increase where people and 

automotive traffic are concentrated. 

An intensive study of lead in urban dusts and soils 

has been conducted in the urban compartment 

(Champaign-Urbana) of the ecosystem. Cadmium 

was also considered, but to a lesser extent than lead. 

Results from about 1,400 samples have shown unusually high concentrations in homes, schools, business establishments, etc., as well as on streets and 

surrounding areas. 

It should be emphasized that the data reported 

here for urban soils are from different locations than 

those discussed in the preceding section. Because 

dust and soil are so intimately connected, it was 

essential that both be collected at the various sampling sites. Thus there is no duplication in the two 

discussions of urban soils. 

Dust samples were collected by a vacuuming technique with the specially designed equipment shown 

in figure 6-16. On carpeted areas, a vacuum inlet 

pressure of 7.5 psi was used, while a full pressure of 

20 psi was applied to other sufaces. Samples were 

taken within a 0.5 m by 0.5 m area. A single pass 

with carefully overlapping, single-direction strokes^ 

was sufficient to remove 90 percent of the lead from _' 

sampling surfaces. 

Dust collected in the nylon chamber, (fig. 6-i6)3 

along with the glass fiber filter, was placed in tared 

glassene bags and weighed. Prior to use, both the; 

filters and glassene bags were temperature and humidity equilibrated for a period of 24 h. Weighings 

were made rapidly to minimize hygroscopic effects. 

Plastic gloves were worn in operations where con-' 

tamination from bare hands might be a problem. 

In very dusty areas (city streets, for example) or 

if stones were present, samples were taken with a 

standard wet-dry industrial-type vacuum cleaner. 

The cleaner was modified by fitting two glass fiber 

filters back-to-back in place of the foam rubber filter 

that protects the motor. The vacuum reservoir was 

lined with a plastic garbage bag that was cut to fit 

and sealed tightly around the vacuum inlet. Fine 

dust that failed to drop into the reservoir was 

trapped by the filters. Final weighings included the 

filters, plastic bag, and the dust sample. All samples 

were dried and passed through a 30 mesh (ASTM) 

stainless steel screen prior to analysis. Lead and 

cadmium were determined by atomic absorption 

spectroscopy. 

Soil samples were taken from the surface 2.5 cm 

with a standard auger. The samples were crushed, 

passed through a 2 mm screen, and dried for 4 h at 

105° C prior to analysis. 

Interior Residential: A total of 239 floor dust samples were taken in 12 homes, four of which were 

FIGURE 6-16.—Vacuuming techniques used in urban dust studies. (A) Equipment 

116 
*gfs$p^»«»j$ m^;- P.14 

-..''/ 

t • 

I -

J ti* 

-A 

sampled twice. Ten of the homes were single-family 

detached dwellings,and two (sites F and K) were 

located in multi-story apartment buildings. All of the 

homes were upper-middle class residences and in 

excellent condition. They were painted with nonlead 

or low-lead paints and located in relatively low traffic density areas. Except for site L, all homes were 

heated with forced air, natural gas furnaces. All dust 

samples were taken in the central area of rooms, 

well away from walls, windows, and doors. 

Eight of the sites (A, B, C, D, E, G, I, L) were 

located where the lead level of outside air was also 

being monitored. The remaining four sites (F, H, K, 

L) were fairly close to monitoring stations. 

Detailed results for rug- and nonrug-covered surfaces are shown for both lead and cadmium in table 

6-12. These data are summarized in table 6-13. Average dust-leadlevels were 600 Mg/g 680 g/m2

 for the 

12 homes. Lead concentrations were higher on wood 

and tile than on rugs—950 and 450 g/m2, respectively. However, the total amount of settled lead 

was higher on rugs when expressed on an area basis. 

This is because rugs accumulate more dust than bare 

floors. The lead levels in dust were similar to those 

reported by Kreuger [19] for suburban Boston. 

In general, the amount of indoor lead in dust was 

proportional to outside air concentrations, even 

though the latter were relatively low (mean, 0.28 Mg/ 

m3, range, 0.18 to 0.34 Mg/m3). Site H was an exception where lower than expected amounts of lead 

were found. The apartment locations (F and K) were 

also lower than anticipated, based on the traffic levTABLE 6-12. -Mean lead and cadmium levels in 

settled floor dusts at residential sites 

Site 

code 

A •• -' JX;. ffi 

C 

D 

E 

F 

G 

H 

1 

J 

K 

L 

Average (12 sites) 

Lead 

Mg/g 

1,440 

690 

940 

760 

900 

350 

240 

500 

170 

270 

430 

460 

600 

Mg/m2 

1,180 

710 

1,700 

580 

1,590 

760 

100 

70 

120 

400 

650 

220 

680 

Cadm 

Mg/g 

28 

19 

10 

10 

20 

48 

26 

25 

7 '• 

9 " 

12 

12 

18 

ium 

Mg/mJ 

26 

14 

31 

• 11 

37 

132 

7 

3 

4 

15 

15 

6 

25 

els in the area. Airborne lead was not measured near 

the apartment sites, and little is known concerning 

such inside apartment buildings. 

Cadmium levels as high as 105 Mg/g and 219 Mg/m2 

were measured in some homes. Extremely large 

amounts, averaging 44 Mg/m2, were found in dust 

from rugs. A major source of this cadmium appears 

to be the rubber backing on many carpets. A random sample of this material assayed 2,000 Mg/g cadmium, and abrasion might well cause its presence in 

dust. 

Interior Nonresidential: For a more complete evaluation of human exposure, it is necessary to establish 

lead and cadmium levels in places where people 

FIGURE 6-16.—(B) Collection technique. 

117 
TABLE 6-l3.-Lead and cadmium content of floor dust in homes 

(rug-covered versus nonrug-c'overed surfaces) 

Site 

code 

Number 

of samples 

Lead 

Mg/g Mg/m2 

Cadmium 

Mg/g Mg/m1 

A 

B 

B (repeat) 

C 

C (repeat) 

D 

E 

E (repeat) 

F 

F (repeat) 

G 

H 

I 

J 

K 

L 

Rugs 

Nonrugs 

Rugs 

Nonrugs 

Rugs 

Nonrugs 

Rugs 

Nonrugs 

Rugs 

Nonrugs 

Rugs 

Nonrugs 

Rugs 

Nonrugs 

Rugs 

Nonrugs 

Rugs 

Nonrugs 

Rugs 

Nonrugs 

Rugs 

Nonrugs 

Rugs 

Nonrugs 

Rugs 

Nonrugs 

Rugs 

Nonrugs 

Rugs 

Nonrugs 

Rugs 

Nonrugs 

All rugs 

All nonrugs 

7 

13 

7 

6 

5 

10 

14 

9 

14 

7 

5 

17 

8 

11 

8 

9 

7 

1 

6 

1 

11 

3 

1 

4 

13 

6 

7 

8 

4 

4 

3 

10 

120 

119 

830 

1,780 

550 

1,440 

420 

480 

640 

770 

520 ' 

2,580 

380 

870 

340 

900 

590 

1,690 

470 

250 

240 

290 

220 

320 

300 

550 

210 

100 

370 

190 

580 

270 

440 

470 

450 

950 

1,490 

1,020 

590 

1,980 

460 

140 

2,710 

360 

1,940 

930 

860 

510 

3,060 

970 

1,110 

1,490 

1,320 

40 

350 

60 

110 

70 

170 

40 

160 

20 

800 

40 

1,160 

140 

640 

90 

1,220 

600 

24 

29 

16 

13 

17 

25 

14 

7 

10 

7 

14 

9 

16 

14 

12 

36 

64 

2 

66 

105 

14 

71 

11 

28 

7 

6 

13 

4 

13 

10 

13 

12 

19 

18 

43 

17 

18 

18 

20 

6 

58 

4 

34 

5 

31 

5 

75 

13 

20 

46 

219 

4 

71 

22 

7 

8 

6 

2 

6 

1 

30 

1 

26 

4 

20 

A 2 

"44 

10 

work, shop, or visit outside the home. In addition to 

direct exposure in these areas, some of the dust may 

be inadvertently carried back to the home on clothing or shoes. 

More than 350 samples were collected in schools, 

hospitals, food markets, and university laboratories, 

offices, and classrooms. As in the homes, samples 

were taken in the central areas, away from walls. 

All areas sampled were in good physical condition, 

with no evidence of peeling of chipping paint. Detailed results are shown in table 6-14 and are further 

summarized in table 6-15. 

Lead and cadmium were found, often in very high 

concentrations, in all buildings sampled. Extreme 

concentrations were found in chemistry laboratories 

at the university. Since levels of both metals were 

much less in adjacent offices, the source of such 

high levels was probably chemicals being used in the 

laboratories. For this reason the data from chemistry 

laboratories were not included in the average values 

shown in table 6-15. Had these data been included, 

the average values of 1,400 Mg/g and 2,040 Mglm2 

would have been almost doubled. 

In general, the levels of lead and cadmium were 

about twice as great as the residential averages. 

This, especially in the case of lead, undoubtedly 

reflected airborne lead levels, which were from two 

to five times greater in nonresidential than in residential areas. Heavier foot traffic may also be a factor in tcking dust and soil into the buildings from the 

outside. Again, high levels of cadmium were associated with rubber-backed rugs or floor mats. 

Outdoor Residential: Airborne lead that moves directly into houses with air currents is perhaps a relatively minor source of interior dust-related concentrations. The major source is more likely related to 

lead emissions that accumulate in dust and soil surrounding houses and are later tracked inside or 

blown in as reentrained dust through open windows 

and doors. The magnitude of such accumulations 

was determined around the 10 single-family dwellings used for the indoor residential study. Eight o£ 

these homes were of frame construction, and the 

other two had painted wood trim. The exteriors 

were all in excellent condition, with no indication of 

peeling or chipping paint. Analyses of paint from 8 

of the houses indicated 1 percent lead and 50 Mg/g 

cadmium. 

Data from 288 samples (all analyzed for lead, 177 

analyzed for cadmium) have been grouped by areas 

around a typical house and are shown in figure* 6-17. 

Both median and range values are shown to compen118 
l?yX*)t.l 

P.16 

* - , 

TABLE 6-\4.-Leadand cadmium in indoor floor dusts at nonresidential sites 

Sampling site 

Halls/corridors 

Roger Adams Laboratory 

Mechanical engineering building 

Krannert court 

Federal buildings 

Rugs 

Nonrugs 

Krannert garage 

Columbia School 

Gregory Hall 

Rooms in university buildings 

University laboratories 

299 RAL 

221 RAL 

57-59 RAL 

136-138 RAL 

11 RAL 

University offices 

105,115,116, 202,222 RAL 

University classrooms 

Various - Gregory Hall 

Various - Lincoln Hall 

Rooms in other buildings 

Federal building offices 

Rugs 

Nonrugs 

Columbia School classes 

..Rugs/mats 

Nonrugs 

All floors ;: 

Dr. Howard School classrooms 

Rugs/mats 

Nonrugs 

All floors 

Carle Hospital complex 

Entry areas (carpet) 

Hospital corridors/rooms 

Food markets 

Plain floors 

Matted areas 

Number 

of samples 

31 

36 

11 

1 

2 

10 

4 

3 

35 

18 

8 

7 

9 

11 

7 

8 

6 

1 

10 

17 

27 

12 

26 

38 

11 

11 

34 

2 

Lead 

J y *SJ

S

. 

2,720 

3,380 

500 

1,710 

4,680 

1,830 

1,010 

740 

11,400 

6,280 

910 

5,740 

8,060 

1,450 

590 

930 

2,320 

2,960 

730 

650 

680 

410 

430 

420 

620 

360 

490 

730 

Mg/m' 

690 

3,010 

1,190 

18,000 

360 

8,650 

1,640 

230 

3,390 

5,770 

120 

3,560 

26^60 

640 

190 

155 

11,780 

560 

3,990 

200 

1,600 

2,360 

210 

890 

7,940 

180 

100 

18,000 

Cadmium 

Mg/g 

14 

9 

7 

23 

369 

5 

9 

5 

185 

86 

33 

69 

79 

13 

24 

1 

1,033 

1,060 

29 

7 

15 

30 

19 

23 

20 

22 

9 

24 

Mg/m* 

6 

8 

21 

240 

28 

25 

15 

1 

57 

74 

4 

34 

302 

7 

3 

0 

2,943 

200 

122 

4 

48 

115 

5 

71 

390 

4 

2 

290 

I «-

t'A' 

sate for variations in data related to differences in 

house locations, orientation, etc. The term "near" 

on the figure is defined as 1 m. 

Lead levels were high at all locations surrounding 

the homes. Soil lead was somewhat greater near the 

road and the house, but it did hot vary greatly from 

one location to another. In contrast, concentrations 

in dust varied considerably. Amounts ranged from 

240 to 6,640 Mg/g away from the house and from 130 

to 11,760 Mg/g near the house. On an area basis, 

amounts were as follows (values expressed as Mg/ 

m

2

): (1) street gutters—median 21,300, range 1,270 

to 211,000; (2) driveways—median 5,820, range 1,050 

to 86,000; (3) walks—median 1,590, range 720 to 

15,200; (4) near house—median 1,840, range 200 to 

9,100. 

Cadmium levels were somewhat higher in soils 

and dusts near the house (1 Mg/g in soil, 6 to 8 Mg/g 

in dust). Total cadmium levels in dusts were relatively uniform, ranging from 7 to 20 Mg/m2

-

The houses used in this study represent relatively 

ideal conditions: low traffic density in the vicinity; 

use of low-lead or unleaded paints, and excellent 

maintenance of both interiors and exteriors. Soil and 

dust lead levels increased dramatically around houses that did not meet these standards. This was 

TABLE 6-15. -Mean lead and cadmium levels in 

settled floor dusts at nonresidential sites 

Surface 

Number 

of samples 

Lead 

Mg/g Mg/m2 

Cadmium 

Mg/g Mg/m2 

Rugs/mats 

Nonrugs/mats 

All floors 

42 

212 

254 

860 

U 0 0 

1,400 

6,670 

1,120 

2,040 

70 

19 

44 

604 

12 

110 

119 
P.17 

m 

40wm<20-H9 BW \JCHH • -

r f

.

p

?*/i g ' 

INTERIOR 

600ppm 

(170-1440) 

• ''yy»y.r •..-yy: 

-

 AJ^y.'^kl0^ 

REAR LAWN ^ ' 

NEAR HOUSE 

lOOppra (20-1060) 

1160 ppm 

;I30-II760) 

NEAR LAWN 

SOppm (3O-990) 

'JkV 

* * FRONT SURRJCE 

X NEAR HOUSE 

FAR FRONT LAWN70ppm (20-IKM 

590 ppm(240-2790LWALK 

<£ r£-

180 ppm (90-470 ) PARKVMr 

IKOppm (290-5020) GUTTER 

FIGURE 6-17.—Composite diagram showing lead in soil (median and range values) in residential areas. 

shown in a special study of areas surrounding 7 additional frame structures. Each was painted with an 

identical type of leaded paint (27 percent Pb by 

weight). They were located in a higher traffic density 

area where airborne lead contents were two to three 

times greater than in the previously mentioned residential area. These houses are not now used as personal residences, although they were in the past. 

Soil lead levels are shown in figure 6-18 as the 

broken line for painted frame houses. Soil lead levels were much higher around these 7 houses as 

compared with the 10 homes prevously discussed. 

The largest increases were in soil adjacent to the 

curb and near the house. However, these maximum 

values were of the same order of magnitude as those 

in settled dusts on walks and driveways of the 10 

houses painted with low-lead paints. 

Outdoor Nonresidential: Lead and cadmium 

concentrations were determined in soil and dust 

samples around several of the nonresidential buildings used for the indoor study. Dusts were sampled 

at 7 sites (195 samples) and soil at 20 locations (183 

samples). All samples were analyzed for lead as well 

as 70 percent for cadmium. 

All of the buildings were of brick or stone construction. Traffic density was heavier than at either 

of the two locations discussed above, with volume 

amounting to 5,000 to 20,000 vehicles/24 h. The 

amount of lead in settled dusts, shown in figure 6-19 

as a function of distance from the street, reflected 

the higher traffic volume. Average lead concentrations were about twice as great as those found in the 

residential zone where traffic was much lighter. 

Mean lead accumulations as great as 190,000 Mg/m2 

were found on sidewalks, but the concentrations 

decreased with distance from the street. There was 

no increase in lead values near buildings. However, 

undisturbed dust samples were obtained adjacent to 

buildings at only two locations, and the results were 

inconculsive. 

2500-

2000 

1500 

E 

& 

8

 l00° 

a 

< 

a 500 

i — i 1 1 1 1 r 

•—• Stone Structure, High Traffic 

*—» Painted Frame (High Lead), High Traffic ' 

OR-OO BUILDING 

^ ^ UNE 6-9 9-12 12-15 18-21 

DISTANCE FROM CURB, m 

FIGURE 6-18.—Mean lead concentration in soils around stone 

and painted frame buildings in high-traffic areas. 

In figure 6-18 soil lead levels around stone 

structures are designated by a solid line, as a function of distance from the curb. Levels were highest 

at the building line, then dropped rapidly and increased again nearer the street. 

In the nonresidential area soil lead contents were 

several times greater than the residential values. 

Also, concentrations at the curb were much greater 

than those found in the special study of 7 houses 

painted with leaded paint, (figure 6-19) In both cas300000 

-250,000 

-20OJ0OO , £ 

5t 

- 150,000 

100,000 

50,000 

2 

z 

3 

1-3 3-6 6-9 9-1 2 BUILDING 

LINE 

DISTANCE FROM CURB, m 

FIGURE 6-19.—Mean lead concentration in dusts from nonresidential sites. 

120 
P.18 

assan 

es, the higher lead values reflected the greater traffic 

density in nonresidential areas. 

Cadmium levels averaged 1 Mg/g in soils and 2 to 6 

Mg/g in dusts with no well-defined trends. Total cadmium in dust decreased from 134 Mg/m2

 at the street 

to 1 Mg/m2 nea r tn e building line. 

Sources of Lead: The accumulation of lead in dusts 

and soils around buildings appears to be directly related to the volume of traffic on neighborhood 

streets and roads. Similar increases in the lead content of air as a function of traffic density suggest 

that the major source is exhaust emissions following 

the combustion of leaded gasoline in automobiles. 

Lead deposited on streets, sidewalks, and driveways 

is subject to further distribution by the physical 

forces of wind and water. Windblown particles associated with dust are apt to be redeposited within the 

urban environment because of the extremely complex wind currents caused by buildings and street 

canyons. As a consequence, the rather large buildup 

of lead in soil and dusts around buildings should be 

expected. 

The degree to which leaded paint contributes to 

lead concentrations in soil near buildings is not so 

clear. Leaching from leaded paint is obviously a 

source, as shown by the higher concentrations of 

soil lead near the 7 frame houses painted with leaded paint, as compared with those near the frame 

dwellings where low-lead paints were used. 

However, a further comparison of the same 7 frame 

houses wth the brick and stone buildings (fig. 6-18) 

shows twice the concentration of soil lead near the 

building line of the latter. Although the brick and 

stone buildings had painted wood trim, it is highly 

improbable that this relatively small amount of 

painted surface could account for the difference. 

Lead washed from unguttered roofs, ledges, and 

walls is a more likely major source. Lead subject to 

washoff could be particulates deposited directly 

from the air or associated with windblown dust that 

collects on buildings. 

Concentrations of lead in house dust may come 

directly from airborne sources or indirectly from 

exterior soil and dust. The airborne contribution 

would be greatest during warm weather when windows and doors are open for ventilation. In contrast, 

dust and soil are tracked into houses during all seasons and are likely to be the major source of lead. 

Of the two, dust is perhaps the most important. 

Overall lead values are higher in dust, and it is continually being blown around by the wind. Soil is 

generally more stable, especially around established 

buildings where it is usually covered with vegetation 

and less susceptible than dust to wind transport. 

v.,, Health Implications: Obviously, the large quantities of lead_ and cadmium in urban environments 

- raise questions about the possible effects of increased exposure on human health, especially that 

of small children. In the absence of clinical evidence, it is only possible to conjecture these effects. 

Because small children commonly play on the floor 

and the ground, and also put their hands (or almost 

any available object) in their mouths, the potential for 

increased ingestion of these toxic substances most 

certainly exists. It is significant that this potential 

exists in well-maintained, better homes and not just 

in the .rundown tenement, with its peeling and chipping paint, that is sually associated with the critical 

ingestion of lead by children. The mere fact that 

such conditions exist in heretofore unsuspected 

neighborhoods should be recognized by medical 

diagnosticians and clinicians. 

SMALL MAMMALS 

Samples of small mammals were obtained by 

snap-trapping from the following situations:; within 

10 m of a high-use road (> 12,000 vehicles/24 h); 

within 5 m of medium-use roads (2,000 to 6,000 

vehicles/24 h); and within 5 m of low-use roads 

(4,000 vehicles/24 h). Control samples were taken 

from situations at least 5 m away from any road 

(normally the closest road was one with low traffic 

volume). Trapping was done seasonally (November, 

March, June, and August). 

All specimens were washed thoroughly in glassdistilled water to remove as much particulate lead 

from the fur and skin as possible; the specimens 

were then freeze-dried. The entire animal (including 

the digestive tract) was processed when the dried 

specimen weighed less than 10 g. Specimens heavier 

than 10 g were ground in a blender and 1 g subsamples were processed for lead analyses. Individuals 

were also selected from each trapping for tissue 

analysis. All lead concentrations were recorded in 

Mg/g (du). 

All species except the white-footed mouse, Peromyscus leucopus, had higher lead concentrations in 

habitats adjacent to high-traffic roads, (table 6-16). 

Since the home range of the white-footed mouse 

averages more than 50 m in diameter, even those 

individuals caught nearest the highway were undoubtedly spending a considerable amount of time 

much further removed. This probably accounts for 

the low level of lead in this species. 

Lead concentrations in small mammals taken 

along medium-use roads were usually intermediate 

between those taken near low- and high-traffic roads. 

There was no significant difference in lead concentrations in small mammals along low-traffic roads 

and those taken more than 50 m from any road. 

Along high traffic roads there was a correlation 

between habitat requirements and lead concentrations in small mammals. Species that require dense 

vegetation and do not range out into cultivated fields 

(Microtus ochrogaster, prairie vole; Blarina brevicauda, short-tailed shrew; Cryptotis parva, least 

shrew; and Reithrodontomys megalotis, white harvest mouse) had higher lead concentrations than did 

those that do extend their ranges into cultivated 

areas and thus out more than 50 m from roads; (Peromyscus mainculatus, white-footed mouse; Mus 

musculus, house mouse). There was no correlations 

between lead concentration in the small mammals 

and the season of the year. 

Along heavy-use roads there was a general correlation between feeding habits and lead concentra121 
P.19 

TABLE 6-16. -Lead content of small mammals1 

Species 

Blarina brevicauda 

Crvptotis parva 

Peromyscus maniculatus 

Peromyscus leucopus 

Reithrodontomys megalotis 

Microtus ochrogaster 

Mus musculus 

Spermophilus tridecemlineatus 

High 

(12,000) 

4

15.2 (46) 

12.3 (13) 

4

 5.5 (57) 

2.6 (16) 

10.8 (32) 

4

 8.2 (40) 

6.9 (51) 

-

Lead concentration (jig/g dry 

Traffic levels5 

Medium 

(2 to 6,000) 

4

 6.5 (71) 

5.4 (3) 

3.7 (103) 

2.6 (23) 

3.8 (23) 

4

 4.3 (60) 

3.5 (150) 

8.2 (13) 

Low 

(<400) 

4

 3.9 (49) 

3.2 (3) 

4

2.6 (63) 

-

3.1 (6) 

"2.6 (50) 

4.2 (59) 

-

weight) 

Fields3 

3.6 (16) 

7.4 (7) 

2.8 (99) 

2.7 (4) 

3.1 (20) 

3.3 (13) 

• 4.6 (104) 

4.3 (17) 

-1 

^ S 

Urban 

31.7 (37) 

- . 

12.1 (8) 

- • -A 

-

11.2 (8) ' 

13.7 (4) " 

16.0 (1) 

'Sample size in parentheses. 

2Vehicles/24 h. Animals taken within 10 m of road. 

3

 Animals taken more than SO m from a road. 

4

 Difference between lead concentrations of samples of a given species from the indicated sites significant at P < .01. 

tions in the body tissues. Insectivores (the shrews) 

had the highest concentrations of lead; herbivores 

(prairie voles) had intermediate levels; while granivores (deer, white-footed and house mice) had the 

lowest levels of lead recorded. The white harvest 

mouse (a granivore) did not fit this pattern; likewise, 

Spermophilus tridecemlineatus, 13-lined ground 

squirrel (also a granivore), showed higher levels of 

lead than other species along medium-use roads. The 

reasons for the differences in these two species 

could not be determined; the small sample size may 

have been at least partially responsible in regard to 

the 13-lined ground squirrel. 

The higher lead levels in the shrews may have 

resulted from food chain concentration. Insects, the 

major diet of the shrew, taken from areas adjacent 

to high-traffic roads, also showed relatively high 

concentrations of lead. Carnivorous insects at these 

sites displayed higher lead concentrations than did 

herbivorous or granivorous species. 

Lead concentrations in the organs and tissues of 

the small mammals itemized iri table 6-17 were gen-

, erally highest in the bones; other organs and tissues 

; did not have lead concentrations significantly higher 

than that of the total body. The lead levels in bone 

were generally low in terms of absolute amounts, 

, averaging 109 Mg/g for three specimens of the white 

;

 harvest mouse and 67 Mg/g for 49 specimens of the 

short-tailed shrew. There, was no indication of lead 

' concentrations in any organ that could cause pathological problems in the individual. 

Due to their size, only selected organs and tissues 

of the larger mammals were analyzed for lead .content. The organs were removed from the animal, 

; freeze-dried, and then analyzed. The results are presented in table 6-18. 

' Although the absolute values were low for the 

large mammals in both the rural and urban areas, the 

; animals captured within the urban compartment (it 

was assumed they spent most of their lives therein) 

TABLE 6-17. -Mean lead concentrations in organs and tissues of small mammals 

Lead concentration 0ig/g dry weight) 

Species 

Blarina 

brevicauda 

Microtus 

ochrogaster 

Peromyscus 

maniculatus 

Mus 

musculus 

Riethrodontomys 

megalotis 

Exposure 

High 

Medium 

Low 

High 

Medium 

Low 

High 

Medium 

Low 

Control3 

High 

Medium 

Low 

Control 

High 

Medium 

Low 

Total 

body 

18.4 

6.7 

5.7 

5.1' 

5.9 

1.9 

'6.3 

4.3 

3.3 

3.1 

6.8 

6.0 

6.7 

2.0 

12.3 

3.1 

2.7 

Gut 

24.0 

7.0 

3.1 

11.0 

18.4 

2.8 

19.2 

6.0 

4.5 

4.3 

18.6 

8.8 

4.8 

2.7 

17.8 

6.2 

3.5 

Spleen 

4.5 

3.6 

2.3 

5.3 

2.2 

2.4 

19.4 

3.0 

6.5 

3.7 

12.1 

3.1 

5.1 

2.1 

14.5 

9.2 

5.6 

Liver 

4.6 

2.0 

1.0 

1.6 

1.2 

1.0 

3.5 

1.7 

1.8 

1.1 

2.9 

1.6 

1.6 

1.9 

4.7 

1.1 

2.3 

Lung 

16.9 

5.6 

7-8 

2.8 

1.8 

1.3 

6.4 

2.4 

6.1 

1.5 

2.8 

3.4 

1.7 

3.4 

20.9 

4.2 

4.7 

Kidney 

12.4 

5.8 

3.9 

8.1 

7.6 

2.8 

7.9 

9.0 

3.0 

1.8 

8.1 

6.6 

3.1 

3.4 

__ 

2.1 

4.8 

Bone' 

67.1 

19.9 

12.2 

16.6 

23.2 

4.6 

24.6 

8.0 

6.4 

5.7 

19.2 

21.0 

23.5 

9.3 

109.5 

' _ 

18.4 

• 

Muscle1 

9.7 

5.7 

5.4 

8.2 

3.0 

2.0 

6.8 

7.4 

1.8 

2.1 

5.9 

3.9 

3.4 

3.8 

27.5., 

4.4 

-

' Femur 'Thigh 3

 Fields more than 50 m from a road. 

122 

S.f) 

i 
TABLE 6-1 S.-Lead concentration (ug/g dry weight) 

' in organs and tissues of large mammals 

Lead concentration (Mg/g dry weight) • 

r —— - ' " 

Area Number Spleen Liver Lung Kidney Bone1 Muscle2 

Urban 

Rural 

2.4 

0.4 

7.9 

1.4 

3.1 

0.6 

8.8 

3.7 

21.8 

3.0 

0.9 

0.4 

' Femur. 

2

 Thigh. 

3Gray squirrel, 3; opossum, 2;raccoon, 1. 

4

 Gray squirrel, 1; fox squirrel, 1; raccoon, 2; rabbit, 1; gray fox, 

had higher lead concentrations than did those from 

(he rural compartment. 

Total body lead concentrations appeared, in general, to have been relatively low in all species of 

mammals studied. There was no information as to 

whether lead concentrations such as those found in 

this study would have influenced the various population parameters. It was also not known what effect, 

if any, such lead concentrations would have on the 

reproduction and survival of individuals living adjacent to high-use roads. 

However, even if lead had a deleterious effect, it 

probably would not be a significant factor affecting 

populations of the species studied. Habitats within 

50 m of heavy-use roads constituted only 12.5 percent of the total available habitat for the prairie 

vole, white harvest mouse, and least shrew; 11 percent of the available habitat for the short-tailed 

shrew; less than 1.5 percent of that for the deer and 

house mouse; approximately 10 percent of that for 

the'"13-lined ground squirrel; and less than 1 percent 

of the total available habitat for the white-footed 

mouse. Any increased mortality or reduced reproduction resulting from the lead taken up by small 

mammals would affect only a minor segment of the 

total population of any species in the watershed. 

Such losses would quickly be replaced by dispersal 

from adjacent populations. 

It is highly doubtful that the very low concentrations of lead in the larger mammals could have a 

significant impact on the population dynamics of 

these animals. 

Birds 

Samples of the bird population were obtained by 

shooting individual specimens with a pelletgun or 

shotgun with copper shot. Several factors were considered in obtaining specimens from areas of high 

environmental lead. First, few birds nest close to 

roads with heavy traffic. In addition, the territories 

of birds are sufficiently large that individuals nesting 

adjacent to a road would spend a major part of their 

time outside the zone of high lead concentration. 

Thus birds from the urban compartment would be 

more representative of those living in high-lead situations, and most of the samples for the high-lead 

area were taken there. However, 4 specimens of 

breeding red-winged blackbirds were taken from a 

marsh 5 m-from an interstate highway. Control specimens for each species were taken from sites more 

than 50 m from any road. 

In almost all cases, the birds from the urban compartment and the red-winged blackbirds obtained 

along the interstate highway had higher lead concentrations in the organs and tissues sampled than did 

individuals from rural areas, (table 6-19) The feathers and bones (and in starlings, the kidneys) had the 

highest lead concentrations of any tissue sampled 

from terrestrial vertebrates. Lead concentrations 

were no higher in the robin and red-winged blackbird, 

which feed extensively on invertebrates, as compared with seed feeders (i.e., House sparrow) or 

omnivores (the remaining species). Although sample 

sizes were too small for statistical analysis, adult 

house sparrows, starlings, grackles, and robins had 

somewhat higher lead concentrations in most tissues 

than did immature individuals. 

The highest concentrations occurred in the feathers and bones of urban birds, relatively "inactive" 

TABLE 6.-19. -Lead concentration in bird organs and tissues from areas of high-lead and low-lead environments1 

Species 

Red-winged 

blackbird 

House 

sparrow 

Starling 

Grackle 

Robin 

Lead level 

Low (10) 

High (4)5 

Low (16) 

High (11) 

Low (11) 

High (13) 

Low (10) 

High (11) 

Low (10) 

High (10) 

Feathers 

26.5 

66.8 

27.0 . 

158.3 

6.4 

225.1 

36.0 

81.4 

25.3 

79.7 

Lead concentration (/ug/g dry weight) 

Gut 

3

2.1 

3

 2.6 

2.3 

26.2 

1.3 

6.0 

1.4 

10.2 

3.2 

24.5 

Liver 

5.8 

1.2 

0.6 

12.0 

4.0 

16.1 

2.5 

12.1 

2.4 

10.5 

Lung 

0.4 

4.1 

0.9 

6.9 

3

2.8 

3

5.2 

3

 2.3 

2.7 

2.2 

10.3 

Kidney 

3

2.1 

3

4.1 

3.5 

33.9 

3.6 

98.5 

3.5 

13.5 

7.3 

25.0 

Bone2 

6.9 

9.1 

16.9 

130.4 

12.8 

213.0 

21.5 

62.8 

41.3 

133.7 

Muscle3 

3

 0.8 

3

 0.6-

0.9 

2.1 

3

 0.8 

3

 2.4 

0.8 

1.4 

3

1.0 

•

 31.2 

'&?. 

,

^ . 'Sample size in parentheses. 

2

 Femur. 

'Pectoral. 

j ^ -y.

 4 Differences between low and high lead environments not significant at the P < .05 level; all others significant at least at the P < .05 level. 

Samples taken 10 m from interstate highway. 

%£>* 123 

246-867 O - 77 - 9 
P.21 

tissues. However, it is highly doubtful that the lead 

concentrations found in even the more critical organs were great enough to affect the survival of 

birds. 

In contrast to some observations of insectivorous 

small mammals, there was no indication of foodchain concentration of lead in birds in this study. 

The prominent insectivorous species had no higher 

concentrations than did the seed, fruit, or omnivorous feeders. Although the birds were obtained during the spring when many were feeding on fruits and 

berries, the young birds should have had diets consisting primarily of invertebrates. However, in most 

instances where there was a difference, the young 

had lower levels than the adults. It would appear 

that age is more important in the accumulation of 

lead than actual feeding habits. 

Total Lead in Terrestrial Vertebrates 

Estimates of the total amount of lead in small 

mammals in the rural compartment were as follows: 

(1) If all species were at a maximum population 

density at the same time, the total amount of 

lead stored would be 47.2 g. 

(2) If all species were at their lowest population 

density at the same time, they would contain a 

total of 2.2 g. 

(3) The best estimate of the average amount of 

lead in the mammal's body at ajny given time 

was 23.7 g. 

Thus the amount of lead, in the total standing biomass of small mammals in the ecosystem at any given 

time was very small, representing an insignificant 

factor in the flux of lead through the ecosystem. 

In conclusion, terrestrial vertebrates do hot appear 

to be significantly affected by current environmental 

concentrations of lead from vehicle exhaust. Neither 

do these animal groups appear to be significant factors in the lead flux in either the urban or rural compartments of the ecosystem. 

Insects 

Insect communities in the ecosystem were sampled on a weekly basis during the 1973 and 1974 

growing seasons. Sample sites were located in various compartments of the ecosystem primarily in 

relation to potential lead input. High-lead-input areas 

were close to an interstate highway bordered by. 

mowed grass (> 12,000 vehicles/24 h); intermediate 

areas were along secondary roads (2,000 vehicles/24 

h); and low-input areas were remote to traffic or less 

than 500 vehicles/24 h. Samples were also taken in 

fields of corn and soybeans, both adjacent to the 

interstate highway and remote from heavy traffic, 

and in remote areas of natural vegetation. Samples 

were collected with a portable suction trap, sorted, 

dried for 48 h at 85° C, and weighed. Mass collections of insects for lead analyses were made by 

walking at a set distance from the pavement for 

about 10 min. Additional collections, used to estimate 

insect biomass per unit area, were taken by placing 

the suction trap nozzle diameter 34 cm) vertically 

onto the ground and extracting the insects from this 

known area (0.0855 m2) of substrate. Insects were 

categorized according to their feeding habits: 

sucking plant juices, chewing plant parts, or preying 

upon other insects. Samples from a given site within 

the 3 categories were composited until about 1 g 

(dw) of insect material was collected. This material 

was then analyzed for lead content by atomic absorption spectroscopy. 

No significant differences in the lead content of 

insects were observed between samples taken atdifferent sites with the same traffic density and vegetation type, nor between samples taken at different 

times of the year. Therefore, the data were grouped 

. 

TABLE 6-20.-Mean lead content (ug/g) in the urban and rural compartments ofthe ecosystem 

Sample site 

Urban 

High traffic volume 

Intermediate 

Low traffic volume 

Rural 

High traffic volume 

Low traffic volume 

Remote from traffic 

Urban 

High traffic volume 

Intermediate 

Low traffic volume 

Private yard 

Rural 

Low traffic volume 

Remote from traffic 

Leaf-hoppers 

(Cicadellidae) 

15.0 

5.7 

11.6 

10.5 

7.8 

4.1 

3.1 

3.4 

12.9 

3.5 

Plant bugs 

(Miridae) 

29.5 

6.2 

11.0 

7.5 

5.4 

9.8 

3.0 

3.4 

3.9 

Long-horned 

grasshoppers : 

I (Tettigoniidaej 

63.2 

77.4 

49.4 

44.5 

4.8 

-

-

Short-horned 

grasshoppers 

(Acrididae) 

1973 

57.5 

13.4 

10.8 

1974 

-

Flower Qies 

(Syrphidae) 

39.6 

24.9 

6.7 

12.9 

15.8 

5.5 

15.5 

3.0 

4.8 

8.4 

-

Ants 

(Formicidae) 

99.1 

54.6 

66.8 

52.3 

21.5 

10.4 

45.1 

13.3 

"': 20.1 

27.0 

2.4 

3.8 

Lady beetles 

(Coccinellidae) 

-

-

3 

11.3 

8.3 

10.7 

3.3 

14.0 

3.7 

.a * * 

124 
and analyzed for differences between insect feeding 

types and between each of the major traffic density 

and vegetation categories. . . *; 

Lead content in insects was positively correlated 

with lead-emission levels, decreasing from areas of 

high-traffic volume to areas remote from roads, (table 6-20) A comparison of families sampled during 

1973 and 1974 shows that the lead concentrations in 

1974 were about 50 to 60 percent lower than in 1973. 

The reasons for observed populations shifts and 

lower lead levels are unknown. 

In high-lead-emission areas, there was a trend of 

increasing lead content from sucking, to chewing, to 

predatory insects; no such trend was evident in lowemission areas, (fig. 6-20) [20] Chewing insects probably ingested more lead from surface deposits on 

leaves than did insects sucking liquids from the internal vascular tissues of plants. Data on predatory 

insects that feed on lead-containing herbivores suggested that lead was selectively retained in the body, 

leading to biological concentration in this two-trdphic-level system. There was no evidence of lead 

concentration by herbivorous insects. 

There was also a decrease iri the lead content of 

insects with increasing distance from a high-trafficvolume highway, (table 6-21) This pattern was similar to that for lead in soils and plants. 

The biomass of insects, estimated by suctiontrapping a known area, differed at each locality. 

Near the interstate highway, from 0 to 7 m from the 

pavement, the mean biomass was 0.324 g/m2; the 

mean lead content of 25.3 uglg, resulting in a lead 

concentration of 8.21 Mg/m2- From 13 to 20 ms from 

the interstate, the biomass was 0.408 g/m2; the lead 

content was 10.9 jug/g, resulting in a concentration of 

4.43 Mg/m2- At Brownfield meadow next to a low-use 

road, the biomass was higher: 0.500 g/m2 with a 

mean lead content of 10.2 ppm, yielding a concentration of 5.07 Mg/m2

. The levels of lead per unit 

area were much lower in sites remote from roads and 

in agricultural crops, even though crops adjacent to 

the interstate (i.e., about 30 m from the pavement) 

were sampled. Natural vegetation habitats had a 

mean insect biomass.of 0.378 g/m2, while soybean 

and corn fields had an insect biomass of only 0.146 

g/m2. Lead concentrations were 1.58 Mg/m2 and 0.61 

f-glm-, respectively. The low insect biomass and 

resulting low lead concentrations in cropped areas 

may be attributed to the low diversity of habitats in 

cultivated fields, as well as to the use of insecticides. 

Sh 

TABLE 6-21 .-Lead concentration of insects at two distances 

from a high-traffic-volume road (interstate highway) 

p^jjL '"sect feeding type 

Lead concentration (jig/g) 

0-7 m from 

pavement 

13-20 m from 

pavement 

Sucking 

Chewing 

Predatory 

Mean 

15.7 

27.3 

31.0 

24.7 

9.8 

10.4 

20.0 

13.4 

•Mr 

- Mr 

E 

QL 

a. 

UJ 

1 -

z 

O 

O 

Q 

< 

30 r 

25 

20 

15 

10 

5 

L H 

SUCKING 

L H 

CHEWING 

L H 

PREDATORY 

FEEDING TYPES 

FIGURE 6-20.—Lead content of various insect trophic levels 

for low (L) and high (H) traffic areas. 

Because about 75 percent" of the ecosystem consisted of cultivated, land areas with low insect biomass and because the levels of lead in the existing 

insect population were relatively low, it seems that 

the insect component of the ecosystem did not act 

as a reservoir for large quantities of lead. However, 

insects did contribute significantly to the flow of 

energy and pollutants up the food chain, and lead 

concentration near high-emission areas could result 

in poisoning of insect predators. 

Conclusions 

Lead in the terrestrial portion of the system was 

concentrated in the soils, plants, animals, and insects in the urban area or near high-traffic-volume 

highways. Samples taken in locations remote from 

traffic sources had relatively low lead concentrations, which may be considered to represent the 

background level. However, because of the considerable enhancement of lead concentrations in soils 

and organisms collected near high-traffic areas and 

because of the increase in the environmental lead 

load with time, as shown by tree-ring studies, it is 

important that areas with high-traffic volumes be 

closely monitored in the future to ensure that environmental lead concentrations do not reach toxic 

levels. Additional studies in these high-lead environments are currently in progress to evaluate the possible loss of plant or crop productivity. It is critical 

that threshold as well as toxic concentrations be 

125 
determined, especially in the case of plant productivity, to allow a more thorough evaluation of the 

lead problem. 

LEAD IN THE AQUATIC ECOSYSTEM 

From the terrestrial part of the ecosystem, lead 

enters the aquatic system primarily in surface runoff 

as suspended particles or adsorbed to soil particles. 

Atmospheric fallout, aerosols scrubbed from the air 

by precipitation, and direct contact with products 

containing lead are other sources of lead to the 

aquatic system. Since many aquatic systems have no 

major exports of lead, they must be considered potential sinks for lead pollutants. 

The sediments, plants, invertebrates, and fish in 

the streams were examined to determine the distribution and accumulation of lead by higher trophic 

levels, and to measure the physical transport of lead 

by aquatic invertebrates and fish. 

The Saline Ditch drainage above' the village of 

Mayview (which includes all of the ecosystem under 

study) was divided into four sectors—rural, urban, 

marginal, and combined, (fig. 6-21) The 14 sampling 

stations assigned to the. various sectors included a 

variety of habitats and localities, (fig. 6-21) 

Essential measurements of stream size and character were made and updated throughout the study 

period. Width, depth, current velocity, and substrate 

type were measured on transects at 400 m intervals 

along the stream length. Discharge, bottom composiTABLE 6-22. Substrate composition ofthe benthos sampling 

stations in various parts ofthe Saline Ditch drainage 

RURAL 

SECTOR 

.URBAN 

SECTOR' 

I Champaign - Urbana 

City Limits 

Q Sampling stations 

V Sewage treatment plant 

FIGURE 6-21.—The Saline Ditch drainage basin, study area 

divisions, and sampling stations. 

Division-station 

Rural tributaries 

I 

11 

III 

IV 

Rural mainstream 

V 

VI 

VII 

Marginal 

VIII 

IX 

Urban 

X 

XI 

XII 

Combined 

XIII 

XIV 

Sand 

26 

5 

4 

2 

54 

82 

35 

44 

50 

96 

57 

13 

34 

52 

SUt 

50 

95 

96 

98 

28. 

7 

40 

21 

11 

2 

8 

8 

7 

Gravel Rubble 

(percent) 

24 

18 

11 

25 

25 

24 

31 

44 

41 

10 

15 

2 

9 

36 

14 

Concrete ' 

..s^tiM 

•'. , 

• * •••m. 

'*~."r 

-

• • 

i '.. 

26 

20 

tion, and stream area for each station were calculated from these data. 

The rural sector included 136.3 km2 of predominantly agricultural land along the main stream of the 

Saline Ditch and its headwater tributaries north of 

Champaign-Urbana. Most of the 47.5 km of'rural 

streams have been channelized to facilitate drainage. 

Four sampling stations (I to IV) were established on 

the primary and secondary tributaries and three (V" 

to VII) on the main stream. The average discharge 

of the rural sector was about 20 m^/min. The predominant substrate of the tributaries was silt, with 

sand and gravel in the main stream, (table 6-22) 

The marginal sector, a 5.5 km stream section with 

a drainage basin of 22.9 km2, is an extension of the 

rural main stream and was considered a transitional 

area between the rural and urban sectors. Due to the 

complexity of external influences, principally of urban origin, minimal effort was expended on the two 

stations (VIII and IX) in this sector. The discharge 

and substrate composition were very similar to those 

of the main stream in the rural sector. 

The urban sector included 16.1 km2 of the Boneyard Creek drainage basin. The creek, a 4.8 km tributary of the Saline Ditch, is located within the city 

limits of Champaign and Urbana. The average discharge is about 5.0 m3/min. Almost 20 percent of 

Boneyard Creek is routed through channels of 

poured concrete, segments of which have bottom 

sediments entirely composed of sand and gravel, 

(table 6-22) High total dissolved solids and periodic 

occurrences of ammonia characterized the chemical 

nature of the tributary. 

The combined division was comprised of the discharges from the Saline Ditch headwaters, Boheyard 

Creek, and the urban sewage treatment plant. Two 

126 
station's (XIII and XIV) were located along the 10.6 

km length. The discharge from the total ecosystem 

watershed of 60 m3/min. was measured at .station 

XIII downstream of the effluent outlet for the urban 

sewage treatment plant. Urban and rural lands, as 

well as a sanitary landfill, were within the 37.7 km2 

drainage basin of this sector. The substrate was 

almost entirely sand and gravel, (table 6-22) and the 

water was generally high in the nutrients. 

Sediments 

Sediment samples were taken with a 1/300 m2 

position coring device to a depth of 10 cm because 

most of the penetration of benthic organisms and 

water circulation was judged to occur only in that 

portion of the sediment. Samples were screened to 

remove material larger than 2.0 mm in diameter, 

because preliminary work indicated that more than 

90 percent of the lead was associated with smaller 

particles. Samples were dried and thoroughly mixed 

before subsamples of 1 to 2 g, obtained by a rifletype sample splitter, were analyzed for lead. 

The lead concentration of sediment samples 

differed significantly in various sections of the Saline 

Ditch drainage, (table 6-23) The lead concentrations 

in Boneyard Creek sediments of the urban sector 

reached a maximum of 1,100 Mg/g near station XII. 

Sediments at station X, the headwaters of Boneyard 

Creek, had a mean lead content of 584 Mg/g. Other 

urban sediment sampling points showed a wide 

variation in lead content, but were well below the 

mean/value of 387.5 iug/g. However, the urban 

concentration was more than 10 times greater than 

that of the combined sector. Main stream rural 

sediments had lead concentrations less than those of 

the combined sector. There was no significant 

difference in sediment lead concentrations between 

stations on the rural tributaries and those in the 

marginal sector, which receives more lead due to 

some urban runoff. The relatively high concentration 

of lead in the sediments of the rural tributaries 

resulted from the ability of these very fine highly 

organic sediments to bind available lead more 

successfully than the sand that dominates stream 

beds in the marginal and other sectors. The main 

stream rural sections (V to VII) had the lowest 

significant concentrations. 

Lead content of sediments decreased with depth 

as shown by separate analyses of 1 cm segments of 

10 cm core samples taken from 6 rural and 6 urban 

points. Concentrations were exceedingly high in the 

top 1 cm from both areas, (fig. 6-22) These relatively 

high concentrations were probably due to 

accumulation of new lead particles through constant 

mixing at the sediment-water interface. 

Lead storage in stream sediments, especially 

urban areas, was substantial, (table 6-23) Storage in 

the upper 10 cm of sediment varied from 1.5 g/m2 in 

the rural main stream to 5.7 g/m2 in the combined 

sector; a maximum was reached in the urban sector, 

where the mean was nearly 60 g/m2. These values 

were more than 6 orders of magnitude larger than 

the values for storage found in the aquatic biological 

components, (table 6-24) 

Sediment profiles were also examined, from silt 

substrates up to a depth of 30 cm in the urban 

stream and the rural main stream. At quarterly 

intervals during the year, 24 samples were taken and 

averaged with each stream segment. Lead 

concentrations decreased with increasing depth in 

Urban 

Stream Sediment Profile 

f 

570 ppm<^ 

J%J:J K 

f 

Rural 

Stream 

6300ppm 

3750 . 

3050 

— 

2330 

— 

— 

840 

— 

320 

0 - lem 

1 " 2 

2 - 3 

3-4 

4-5 

5-6 

6-7 

7-8 

8-9 

9 - 10 

>» 

342 ppm 

197 

167 

133 

101 

67 

49 

V69 ppm 

FIGURE 6-22.—A comparison of the lead concentration in 1 cm segments of the top 10 cm of 

urban and rural sediments. 

127 
TABLE 6-23.-Mean lead concentrations and storage in sediments, to a depth of 10 cm, 

from the various compartments of Saline Ditch and Boneyard Creek 

Urban Combined Tributaries Marginal Main rural 

Station X-XII 

Number of samples 104 

Lead storage (g/m3) 58.1 

Pb level (Mg/g dry weight) 387.5 

Significance1 

XIII-XIV 

68 

5.7 

37.8 

I-1V 

75 

2.4 

15.8 

VIII-IX 

15 

2.1 

13.8 

V-VII 

47 f 

1.5 •'* 

10.2 

'Common underscore indicates means that are not significantly different at the S percent level. 

both the rural and urban profiles, (fig. 6-23) 

However, the values were much higher for the 

urban stream. The lead distribution pattern of 

stream sediments resembled that of terrestrial soil 

profiles. 

Biota 

The biomass and lead concentrations were determined for aquatic organisms in the drainage system 

and used to calculate lead storage in the biota. The 

biomass in each sector was calculated froni the 

biomass density at each sampling station. Lead concentrations for each sector were determined from 

samples accumulated from all stations in a particular 

sector. The mass (g) of a taxonomic group was multielied by the specific lead concentration (/xg/g) to 

find the lead storage. This method permitted the lead 

accumulation of a taxonomic group to be weighted 

for the amount of habitat suitable for that group. 

Plants: Aquatic plants occurred in all sectors, but 

were abundant only during the summer. Plants and 

invertebrates were sampled together with substrate 

samplers of three sizes and kinds: VA m2 open cylinder, 1/25 m2

 grab sampler, or 1/300 m2 corer. The 

size used depended on the density of organisms. 

Samples were washed on a No. 30 mesh sieve, and 

the plants were separated from each other and from 

invertebrates. Aquatic plants were washed with water, dried, and ground to a powder prior to analysis. ' 

The plant biomass during the warm months was 

highly variable in all sectors, ranging from 0 to 300 

g/m2 (wet weight). The alga Cladophora occurred 

throughout the system and had highly variable lead 

concentrations, ranging from means of 20.1/xg/g (dry 

weight) in the rural sector up to 347 jzg/g (dry 

weight) in Boneyard Creek, (table 6-25) These values 

reflected the relative amount of lead input of the two 

sectors. Potamogeton was common in rural streams 

(30.0 Mg/g lead), while Elodea was an important constituent of the combined sector (89.9/ug/g lead). 

The total lead stored by plants was highly variable 

due to fluctuations in biomass. (table 6-24) 

Invertebrates: Invertebrate samples were obtained 

and separated in the same manner as aquatic plants; 

They were washed in 95 percent ethyl alcohol, 

dried, and ground to a powder for analysis. 

The distribution and biomass of benthic invertebrates were highly variable, (table 6-26) The biomass 

density in the combined sector was consistently 

higher than in the rural or urban sectors, primarily 

because of the increased nutrients available from 

TABLE 6-24.-Seasonal lead storage in biota of Saline Ditch and Boneyard Creek 

Compartment/organism 

Rural 

Fish 

Benthic invertebrates 

Macrophytes 

Total 

Urban 

Fish 

Benthic invertebrates 

Macrophytes 

Total 

Combined 

Fish 

Benthic invertebrates 

Macrophytes 

Total 

Summer 

2.36 

24.07 

1

 298.91 

324.34 

112.22 

1

2,608.70 

2,720.92 

339.44 

1

109.75 

449.19 

Lead concentration Cig/ml) 

Fall 

3.52 

27.45 

30.97 

874.50 

874.50 

899.68 

899.68 

Winter 

2.81 

60.48 

63.29 

4,497.41 

4,497.41 

5,304.96 

5,304.96 

Spring 

2.60 

40.90 

43.50 

839.13 

839.13 

312.85 

312.85 

1

 Highly variable due to fluctuations in biomass. 

128 

4 
•t w.** ^ cs»jj^r^«7; 

P.26 

Urban 

Stream 

570 ppm, 

290 

Sediment Profile 

130 < 

0-10 cm 

10-20 

20-30 

30 + 

Rural 

Stream 

69 ppm 

41 

27 

>I4 

FIGURE 6-23.—Mean lead concentrations (fig/g) in urban and 

rural stream profiles (silt substrate). 

i& 

agricultural runoff and septic tanks in this sector. 

The weighted average biomass densities between the 

rural and urban sectors were similar. During the 

spring and fall, periods of relatively high oxygen 

concentrations, benthic populations may well have 

been limited by substrate instability. In all sectors 

and in all seasons, the biomass density was consistently highest on silt substrates, (table 6-26) In the 

rural sector, nearly 70 percent of the invertebrates 

were found on the 25 percent of stream bottom covered with silt. In most instances, these were areas of 

deposition protected from the current and least subject to disturbance. The instability of these soft substrates, when exposed to increased currents, limited 

invertebrate production in all sectors. Thus substrate 

stability and stream oxygen content were limiting 

factors for benthic invertebrate biomass, which in 

turn affected the biological lead storage and flux in 

all sectors. 

- In general, the benthic populations were highest in 

winter and lowest in summer, regardless of substrate, (table 6-26) These seasons were, respectively, 

the periods of highest and lowest oxygen availability. While the small seasonal differences in the biomass of the rural sector might be explained by natural 

benthic cycles based on oxygen availability, the 

population changes in the urban and combined sectors cannot be explained this way. Here the substantial seasonal changes in biomass occurred mostly 

among tubificids, organisms with nonseasonal cycles. The Tubificidae and Chironomidae, which together comprise more than 95 percent of the benthic 

invertebrates of the urban and combined sectors, 

have respiratory pigments to improve their oxygen 

exchange efficiency, enabling them to survive summers when the oxygen concentration is frequently 

low. 

Seasonal changes in lead concentrations were determined only for the Tubificidae from the urban, 

sector. No significant difference was found injnean 

seasonal lead concentrations for spring, summer, 

and fall. However, the lead concentration in tubificids 

increased from a mean of 322 /zg/g (spring through 

fall) to 484 Mg/g in winter. This peak value corresponds with a period of high surface runoff because 

the ground was relatively impermeable due to freezing. 

Lead storage in the rural and combined sectors 

(table 6-24) varied as a result of changes in biomass, 

but storage in the urban sector reflected changes in 

both biomass and lead concentrations. 

The only measurable biological transport of lead 

in the Saline Ditch drainage was due to the drift of 

aquatic invertebrates. Plankton is essentiaUy nonexistent, and fish movements are minimal. (See table 6-

27.) Samples of drifting invertebrates were taken in 

late summer when peak values should have been 

encountered. A 1 ft2 net of No. 20 mesh Saran cloth 

was placed in the stream for between 30 min. and 1 

h. The samples were taken during the day within 1 h 

after sunset and within 1 h before sunrise. 

Measurements of flow rate through the mouth of the 

net at the beginning and end of each sampling period 

permitted quantification of drift biomass. Samples 

were analyzed for lead concentrations in the drift 

were expressed on a daily basis, (table 6-27) Lead 

fluxes in the urban and rural sectors were similar 

because the low stream flow of the urban sector was 

offset by its relatively high lead concentrations in 

the biota. The amount of lead transported during 

peak periods of stream drift (late summer) was several orders of magnitude less than the amount of 

lead moved in solution or adsorbed to suspended 

material. Thus drift organisms do not constitute a 

significant lead transport. 

Fish: Fish were sampled by confining them in a 

measured portion of stream with 20 ft seines of 3/16 

in. mesh. The upstream seine was slowly moved 

downstream, driving the fish into a bag seine at the 

lower end of the blocked-off section. A series of 

samples from an isolated stream section indicated 

that this technique effectively removed 50 percent of 

the fish population without specific selection, except 

that large carp (Cyprinus carpio) successfully 

avoided capture. The uniformity of the banks and 

bottom of the Saline Ditch, due to earlier channelization, permitted effective use of this technique. 

Fish were sorted after capture, oven dried without a 

preservative, and ground to a powder for lead analysis. 

The biomass distribution of fish was easily determined because they occurred in measurable numbers 

only in the rural sector and portions of the marginal 

sector. The fish population was consistently near 3 

g/m3 (wet weight) in the rural sector. 

Lead concentrations in fish were lower than those 

in aquatic plants or invertebrates, (table 6-25) 

129 
P.27 

TABLE 6-25.-lead concentrations of predominant organisms from 

rural, urban, and combined compartments ofthe Saline Ditch 

Lead concen tration. (Mg/g dty weight) 

Compartment/organism 

Arithmetic 

mean 

Number of 

samples 

Standard 

deviation 

Rural 

Plants 

Invertebrates 

Fish 

Urban 

Plants 

Invertebrates 

Combined 

Plants 

Invertebrates 

Cladophora 

Potamogeton 

Hirudinea 

Oligochaeta 

Tubificidae 

Sphaeriidae 

Lirceus fontinalis 

Hexagenia limbata 

Anisoptera 

Chironomidae 

Decapoda 

Catostomus commersoni 

(white sucker) 

Etheostoma nigrum 

(johnny darter) 

Ericymba buccata 

(silverjaw minnow) 

Notropis umbratilus 

(redfin shiner) 

Pimephales notatus 

(bluntnose minnow) 

Semotilus atromaculatus 

(creekchub) 

Cladophora 

Tubificidae 

Chironomidae 

Decapoda 

Elodea 

Cladophora 

Tubificidae 

Chironomidae 

Physa 

Psychodidae 

20.1 

30.0 

12.6 

13.2 

16.0 

5.5 

7.6 

10.4 

6.6 

20.1 

4.7 

2.4 

4.1 

1.8 

1.9 

2.7 

1.4 

347 

11 

15 

12 

7 

13 

11 

5 

15 

6 

12 

23 

19 

9 

29 

29 

83 

35 

5.1 

5.4 

14.8 

7.6 

11.8 

3.1 

3.4 

9.7 

2.4 

18.2 

5.2 

1.6 

2.4 

0.9 

0.6 

2.7 

0.6 

139 

367 

153 

11 

89.9 

34.9 

48.6 

42.7 

41.7 

32.3 

29 

5 

4 

2 2 / 

Y 

71 

12 

ro 

/• 106^ 

93.3 

7.5 

33.9 

16.4 

25.5 

TABLE 6-26.-Biomass density of benthic invertebrates from 

the Saline Ditch and Boneyard Creek 

• Biomass density (g/m1 wet weight) 

Compartment 

Rural 

Urban . 

Combined 

Substrate 

sat 

Sand 

Gravel 

Weighted average 

SUt 

Sand 

Gravel 

Weighted average 

Silt 

Sand 

Gravel 

Weighted average 

Summer 

9.2 

1.7 

0.6 

6.5 

34.2 

9.8 

3.7 

6.0 

177.5 

28.2 

47.1 

56.1 

Fall 

16.9 

1.8 

1.3 

12.4 

5.0 

12.8 

51.8 

11.2 

587.6 

32.5 

23.9 

73.1 

Winter 

20.5 

3.9 

2.3 

13.8 

64.2 

80.1 

41.8 

1,251.3 

272.8 

299.4 

Spring 

18.9 

1.9 

0.7 

12.2 

63.7 

19.1 

15.8 

313.9 

5.0 

49.1 

130 
TABLE 6-27.-Peak period drift from the Saline Ditch and Boneyard 

Creek and the amount of lead transported by drifting organisms 

• 

• 

Organism 

Rural compartment 

Chironomidae 

Ephemeroptera 

Coleoptera 

Hemiptera 

Tirchoptera 

Physa 

Nematamorpha 

Zygoptera 

Total 

Urban compartment 

Qiironomidae 

Psychodidae 

\ Culicidae 

Amphipoda 

i Tipulidae 

\ , . Terrestrial 

t Total 

Wet 

(g/100 m3 

0.042 

0.006 

0.011 

0.030 

0.002 

0.019 

0.013 

0.001 

0.124 

0.559 

0.067 

0.002 

0.003 

0.002 

0.151 

0.784 

Combined compartment 

X'.' Chironomidae 

Psychodidae 

Coleoptera 

Corixidae 

Gastropoda 

Trichoptera 

Tubificidae . 

Nematamorpha 

Terrestrial, 

I * Total 

i "1» 

1.780 

0.156 

0.010 

0.010 

0.128 

0.007 

0.004 

0.019 

0.016 

2.130 

Peak period drift 

Dry 

) (g/day) 

1.09 

0.14 

0.50 

1.43 

0.07 

0.90 

0.40 

0.05 

4.57 

1.26 

0:15 

-

-

-

0.38 

1.80 

388.8 

35.5 

3.9 

4.0 

50.8 

1.7 

1.0 

4.8 

3.9 

494.4 

Lead 

(mg/day) 

0.01 

0.01 

0;02 

0.10 

— 

0.01 

0.01 

— 

0.16 

0.13 

0.02 

-

0.00 

0.00 

0.00 

0.15 

17.7 

1.0 

0.2 

0.2 

2.8 

0.1 

-

0.2 

— 

22.2 

1 

i** 

i ,• 

J 

i •*• 

Seasonal lead storage in fish was essentially nonexistent, (table 6-24) 

Interactions 

In stream sediments and three selected groups of 

organisms, (fig. 6-24) the lead concentrations showed 

progressive increases that correlated with the relative input received by a particular stream sector. 

Values of lead concentrations from the rural main 

stream and tributaries (considered baseline data) 

were exceeded, successively, by values from the 

marginal, combined, and urban sectors. The highest 

lead concentrations, in all cases much greater than 

any others, were found in the urban division. 

Perhaps the most striking result was the variability 

of lead concentrations n different species from the 

same sector. In the rural sector, where the only 

complex community structure existed, lead concentrations of dry animal tissue ranged from 1.4 to 16.0 

Mg/g. (fig. 6-25)The organisms in the rural streams 

were divided into four groups based on their food 

and habitat requirements. 

The first group—composed of the mayfly (Hexagenia limbata), the Tubificidae, and the oliogchaetes,—burrow into and ingest the substrate. 

[21] These organisms showed a definite preference 

for silt substrate where they were continually exposed, both internally and externally, to high lead 

sediments. 

The second group was composed of the following 

benthic organisms that inhabit the sediment-water 

interface: crayfish (Orconectes virilis), which feeds 

on vegetation and detritus; [22] the pelecypods, 

which are filter feeders that utilize suspended detritus; and the johnny darter (Etheostoma nigrum), a 

benthic, carnivorous fish that occasionally ingests 

detritus and silt. [23] These organisms occasionally 

contacted lead-rich material in their food source and 

environment. 

The remaining two groups consisted of fishes that 

had very little close body contact with settled or 

suspended sediment material. These include the 

white sucker (Catostomus commersoni) and the 

bluntnose minnow (Pimephales notatus), which are 

bottom feeding omnivores that often ingest detritus. 

[24-26] The creekchub (Semotilus atromaculatus), 

silverjaw minnow (Ericymba buccata), and redfin 

shiner (Notropis umbratilus), which comprise the 

fourth group, are principally carnivores. [26-30] 

Their most likely lead source is their food. The 

creekchub's mean lead concentration was significantly lower than those for all other species. It tends 

to be a piscivore, while the silverjaw minnow and 

redfin shiner are usually restricted to eating invertebrates. 

The lack of lead accumulation through trophic 

levels, particularly the low concentrations in the 

carnivores, (fig. 6-25) clearly indicated that lead accumulation by aquatic orgamsms through ingestion 

was of minimal importance. Thus in contrast to 

some terrestrial food chains, there appeared to be no 

biological magnification of lead through trophic levels in the aquatic system. 

Conclusions 

In the rural sector, the highest lead concentrations 

in stream sediments were only slightly higher than in 

the surrounding field soils, while sediments in the 

urban sector were many times higher. Stream sediments acted as a sink where lead accumulated to 

high levels. The highest concentrations were ih the 

urban sector. 

Lead levels of sediments and organisms reflected 

the relative amount of urban runoff entering the 

stream. In the urban sector, a dramatic increase in 

lead accumulation by Tubificidae corresponded to a 

period of increased high lead runoff. 

Lead concentrations of aquatic organisms varied 

substantially within and between sectors. Lead concentrations in the same kind of organisms were generally 2 to 4 times higher in the combined sector 

than in the rural sector. Similar Organisms in the 

urban sector had lead concentrations 10 to 20 times 

higher than those in the rural compartment. The 

mean concentrations for each species within a sector 

were markedly different. Organisms at low trophic 

131 
P.29 

.'.nr • \i 

-r Urban Compartment 

Combined Compartment 

Marginal Compartment 

Rural Main Channel 

Tributaries 

Sediments Tubificidae Cladophoraceae Chironomidae 

FIGURE 6-24.—Mean lead level of representative organisms and sediments of compartments 

of compartments in the Saline Ditch. 

levels had the highest concentrations, while those at 

the top trophic level had the lowest lead concentrations. Thus there was no biological magnification of 

lead through the aquatic trophic structure. 

The biological lead concentrations were apparently 

influenced by the amount of contact an organism 

had with, the substrate. This phenomenon was regulated by habitat preferences and feeding habits. 

Thus the actual amount of lead stored by the biota 

of a stream segment dependends on the types and amount of habitat available, the community composition, and the lead concentration in the sediments. 

Fluctuations in biomass due to changes in habitat or 

community structure were common and caused significant changes in the amount of lead stored. However, lead storage variations in the urban sector 

132 

were a function of biomass and biota lead concentrations. 

The amount of lead transported by drifting stream 

invertebrates was insignificant in this ecosystem. 

SUMMARY AND CONCLUSIONS 

An 86 mi2 watershed was studied to determine the 

movement of lead into and through the ecosystem, 

as well as the effects of lead on various biotic components. Gasoline consumption was the major 

source of lead input to the watershed. It was estimated that the total input to the ecosystem, with the 

exception of air, was 16,000 kg/yr. The 12 mi2 urban 

i 

1 
P.30 

4 

"SB*-

compartment received 75 percent of the total lead 

input. 

The majority of the lead exiting from the ecosystem was carried in tiie drainage water, primarily in 

association with suspended solids. It was estimated 

that 910 kg of lead exited from the ecosystem via 

stream water annually. Of this, 75 percent was from 

the urban compartment. 

With 16,000 kg of lead per year entering the watershed and only 910 kg per year exiting via stream 

water, 14,800 kg per year, or 92.5 percent of the 

lead input, remained within the ecosystem. 

Airborne lead concentrations were low in the rural 

area (0.17^ g/m3), and in the urban area concentrations varied from 1.352 Mg/m3

 on high-use downtown 

streets to 0.287/xg/m3 on low-use residential streets. 

In both the urban and rural compartments, lead 

concentrations were highest in the top 10 cm of soil 

in areas immediately adjacent to streets and roads 

with high traffic volumes. A study of lead in dusts 

and soils in the urban compartment of the ecosystem 

showed high concentrations inside buildings. Lead 

levels in dusts within homes averaged 660 Mg/g and 

680 uglnfi. In nonresidential interiors, dusts averaged 1400 ngjg lead and 2,040 /xg/m2

. The concentrations of lead in dusts and soils around buildings and 

in dusts inside buildings appeared to be directly related to the volume of traffic on neighborhood streets 

and roads. 

Concentrations of lead associated with vegetation, 

in small mammals and other vertebrates, and in insects were also highest in areas adjacent to high-use 

roads and streets. Because the vegetation biomass 

was large, it was estimated that 2,211 kg of lead 

were associatecl with the vegetation of the ecosystem. 

For all animals, the total body lead concentrations 

were relatively low. The highest concentration for 

an urban-dwelling mammal was 31.7 ppm. Although 

there may be some food-chain magnification in insectivores that feed near roads with high traffic volumes, terrestrial vertebrates do not appear to be significantly affected by current environmental lead 

concentrations, nor do these terrestrial vertebrates 

appear to be significant factors in the lead flux in 

either the urban or rural compartments bf the ecosystem. 

In contrast to the case with vertebrates/there is> 

an increase in lead concentrations in insect food 

chains from sucking to chewing to predatory insects 

in high-lead areas next to heavily traveled roads. 

However, the low biomass and low lead concentrations indicate that insects are not a major reservoir 

of lead in this ecosystem. 

In the aquatic system, lead concentrations in the 

top 10 cm of stream sediments were high in the urban stream (387.5Mglg), while rural stream lead concentrations were many times lower. The high urban 

concentrations were related to lead particulates 

washed from the large impervious areas of the urban 

compartment during storms. 

Aquatic biota had lead concentrations many times 

higher in the urban stream than in the rural stream. 

There was no biological magnification of lead in 

aquatic food chains. Lead in aquatic organisms was 

related to the amount of contact with substrates containing high lead concentrations. The stream drift of 

invertebrates was insignificant in transporting lead 

from the ecosystem. 

In conclusion, most of the lead that entered the 

watershed remained within it. The major lead reservoirs were the soils, plants, and stream sediments. 

Creek Chub 

Silverjaw Minnow 

Redfin Shiner 

White Sucker 

Bluntnose Minnow 

Johnny Darter 

Clam 

Crayfish 

Mayfly Nymph 

Leech 

u Aquatic Worm 

Sludge Worm 

SS3 

^ ^ 

SSSS 

N\\\\\\\\^ 

NNWWWWW N 

s\\\\\\\\\\\\N 

sSSSSSSSWSSSWSWSWWSSVI 

\\\\\\\\\\\\\\^^^ ^ 

l\\\\\\\\\\V\V\\\\\^^^ 

s\vv\^v\^^^^^^ 

Lead Levels (ppm-dry weight) — 

FIGURE 6-25.—Relative lead concentrations of organisms from the rural compartment, moving upward in the tropic structure. 

133 
The highest concentrations and a major portion of 

the stored lead were associated with the urban compartment and ares adjacent to high-use rural roads. 

These areas should be monitored in the future to 

detect changes in lead storage and concentrations 

with time and .with additional lead input, to determine if toxic levels are reached. 

Insect food chains and insectivorous birds should 

also be closely monitored in high-lead-input areas. 

Aquatic systems should receive closer examination 

in the future, as sediments are major metal reservoirs. 

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