Open Literature Review Summary

Chemical Name: Atrazine

CAS No: 1912-24-9

ECOTOX Record Number and Citation:

Lakshminarayana, l.S.S., H.J. O'Neill, S.D. lonnavithula, D.A. Legerand, P.H. Milburn.

1992. Impact of atrazine-bearing agricultural tile drainage discharge on planktonic drift

of a natural stream. Environ. Pollut. 76:201-210. (vvt\( \\0 41-~{3 S7 0 )

Purpose of Review:

Determine potential effects of atrazine on an aquatic community. Endpoints from this

study were also used to parameterize the Comprehensive Aquatic System Model (CASM)

and establish the model-associated LOC for atrazine.

Date of Review:

November 5, 2008

Purpose of Study:

This study examines the potential effects of atrazine agricultural runoff to aquatic plants

and animals in a field stream.

Summary of Study Findings:

Methods:

A field experiment was performed at a study area in a rural headwater basin, about 48 km

west ofMoncton, New Brunswick, Canada. The basin area (19 km2 in size) was mostly

used for agriculture - grain-based forage production and pasture, with some areas of

silage com and other crops. The main study area was a first-order field stream flowing

parallel to an 8 ha subsurface tile drained field, which was divided into four plots with

drains placed at 0.8 m depth and 12 m apart (see Figure 1; the setup including drainage

system is further described in a 1989 Agriculture Canada report by Milburn, et al.).

During the 1989 growing season, when the experiment took place, the field was cropped

to silage corn. The four plots drained into individual outlet chambers housed in a covered

building and fitted with flow measuring devices (devices not described). The four drains

fell outside into a small 30 m long channel and were carried to the receiving stream that

is the main object ofthe study. The receiving stream flowed into Salt Spring Brook,

which ultimately flows to the Petitcodiac River. Eleven sampling locations were

established: Sites 1-4 were the drain outlets from the four plots, Site 5 was the small

III1IIIIII

2087867
channel containing the effluent from all plots combined, Sites 6-10 were on the field

stream (8 and 9, upstream ofthe confluence with the small channel containing the plots'

runoff, were considered background), and Site 11 was located on Salt Spring Brook about

2.5 km downstream from the confluence with the field stream. See Figure 1 for a map of

sampling locations. Site 6 and 7 were separated by a small earthen mound about 2 m

wide, and during times ofincreased water flow were almost joined due to water level rise

(this was observed during a heavy precipitation event in November). See Table 1 and

Table 2 for summaries ofthe sampling locations and meteorological monthly averages,

respectively.

On June 6, 1989,just before the start ofthe study, atrazine (no information on product

type) was applied at levels of 4 Llha (not clear whether this refers to dilute product or

active ingredient; no description of application method). No pre-application sampling

occurred. 16.6 mm of precipitation occurred in the area between the time of atrazine

addition and sampling. Water and plankton drift samples were taken starting June 9 and

ending on November 16, 1989, at roughly IS-day intervals. Samplings all occurred

between 09:00 and 12:00. Water quality samples were collected in 1 L plastic bottles and

atrazine samples in I L amber glass bottles. Atrazine water samples were preserved to

pH 9 within 3 hours of collection, and all water samples were stored at 4°C until analysis.

Plankton drift was collected in two ways: first, sterilized 500 mL bottles were immersed

beneath the surface and allowed to till at hand depth (depth not quantified); and second, a

20 11 nitex plankton net scanned the contents oflarge (20 L) volumes of water. The

plankton samples were fixed on site with 5% formaldehyde (for samples used to

characterize flagellates, diatoms, and the cate dinoflagellates) and weakly alkaline

Lugol's solution (for samples used in plankton enumeration). Plankton was counted

using Utermohl's technique (American Public Health Association, Standard Methods/or

the Examination ofWater and Wastewater, 1980) and the samples were studied using a

two- or three-step examination of one chamber with an inverted microscope. The whole

bottom area was examined under a low magnification before high power objective

examination, at lOx, 20 x, and 40x with an eyepiece of 15x. Five to ten perpendicular

stripes across the center and bottom cover glass were counted, keeping the width ofthe

stripe constant by taking I to 5 whipple squares depending on the plankton density.

Water sample analysis was conducted by Environment Canada, Regional Water Quality

Branch Laboratory in Moncton. Major ion and nutrient analysis followed the standards

of Environment Canada's Analytical Methods Manual 1979. Atrazine analyses were

performed using gas chromatography with a nitrogen-phosphorus detector and 30-m

megabore columns (DB-lor DB-17), after XAD-4 resin column extraction, elution with

ethyl acetate, and reduction of ethyl acetate over anhydrous sodium sulfate to 5 mL

volume. When extraneous peaks were observed, columns were cleaned up with

deactivated florisil. Confirmations were performed using a Hewlett-Packard gas

chromatograph with a mass selective detector when concentrations permitted. A blind

quality assurance/quality control program was employed using duplicate and triplicate

samples, lab and field spikes, and blanks. The laboratory's in-house QA/QC and

2
participation in inter- and intra-laboratory round-robin studies also assure the quality of

the analyses.

No statistical analyses ofthe data were performed beyond occasional summary statistics.

Results:

Atrazine concentrations in the samples varied from non-detects (detection limit of 0.001

Ilg/L) to 1.89 Ilg/L. (See Figure 2 and Table 4.) The atrazine concentrations at the

"background" sites (Sites 8 and 9) were consistently lower than those from Sites 5 and

10, but atrazine was often present in the former, indicating the use of atrazine elsewhere

in the watershed. A small cornfield upstream may have been contributing atrazine

runoff; Site 9 (the less upstream background site) always had higher levels of atrazine

than Site 8 (the most upstream site). Site 5, being closer to the tile plots, always had

higher atrazine levels than Site 10.

Water chemistry data were interpreted as showing the dynamics ofseasonal groundwater

contributions as well as changes in water quality due to tile plot runoff. Groundwater

contributions were inferred from observations of apparent base flow conditions at Site 5

during dry spells, as well as high specific conductance and concentration of major ions

(especially calcium and sulfate, indicating flow through the Mississippian gypsum shales

common in the basin). See Table 3 for summary statistics of water quality parameters for

Sites 5, 8, 9, and 10 (no units were provided for any parameters, but based on figure

captions and text discussion, ion concentrations are probably mg/L and specific

conductance is probably IlS/cm). Selected parameters (calcium concentration, N03+N02

concentration, pH, dissolved organic carbon) are also graphed in Figure 3 through Figure

6. For most parameters except dissolved organic carbon, Site 5 had higher concentrations

than the other sites and the background sites had lower concentrations than Sites 5 or 10;

concentrations of potassium and pH levels, however, were similar among these four sites.

The authors interpret the results as indicating effects ofthe tile plot runoff on the stream

water quality, with additional effects due to varying relative flow contributions from

groundwater.

The measurements ofthe plankton drift community found 103 species of phytoplankton

and 10 species of zooplankton, including 76 diatoms, 18 green algae, 5 flagellates, and 5

bluegreen algae. Zooplankton were infrequent. A complete list of phytoplankton species

identified is tabulated in the original paper (Table 4), but is not reproduced here. The

most common phytoplankton species were:

Cocconeis placentula

Cyclotella meneghiniana

Fragilaria crotonensis

F. virescens

Aulacoseria granulate

Melosira varians

Navicula pupula

3
Pinnularia apendiculata

P. borealis

Surirella linearis

S. ovulum

S. tenera

Synedra nana

S. ulna

Tabellariafenestra

T jlocculosa

Spirogyra sp.

Trachelomonas dybokskii

Phytoplankton cell counts and number ofspecies per sample (both net and water

samples) are provided in Table 5, Table 6, and Table 7. The results show higher plankton

numbers at the background sites than in the sites affected by tile plot runoff. These

plankton reductions in the field stream tended to become less dramatic after each

confluence and with distance downstream. Numbers ofspecies in each sample also

varied dramatically, in time as well as by sample. (No statistical analyses provided.) Sce

Figure 7 for the variation of phytoplankton cell counts over time for Sites 5,8,9, and 10,

and Figure 8 for the distributions of different plankton groups by time and site. Increases

at Sites 10 and 11, as compared to those ofthe background sites, are noted during

September - November 1989.

Microzoop1ankton were rare, and taxa represented were Amoeba, Braehinesta paludosa,

Chaoborus, Colpoda, Daphnia, Limnoealanus, Nematode, Paramercium, and Tintinnid.

From September to November zooplankton were found at Sites 8 and 9 (150 - 14,630

cells/L) with fewer numbers at Sites 6 and 7 (570 - 933 cells/L), but overall the

distribution was "patchy".

Comparing Figure 2 with Figure 7, the authors state that changes in phytoplankton cell

numbers are associated with atrazine concentrations, although they also note strong

effects of nitrates levels on the phytoplankton levels (higher phytoplankton levels with

more nitrates). (No quantitative analyses or statistics are provided.)

4
Figure 1. Diagram ofstudy location, including stream network (arrows indicate direction offlow)

and sampling sites.

5
-+- Site-5

-0- Site-e

"-!i,m. Site 9 -.--..~ 5 it~ 10

--:l

./ I ,

/ ,

/ i

..J' .)i I .o' ! I .• II

}/

:'/ '

·'\t ;/ J' ..... \ it . \ , ~--"""'i_.~.~--rL,._... Sep Oct Nov Dec

O.t~

• \

0.0100·1

0001Ot·

0000' ~~- "-~""-f-'~

Jun Jul

lOCHXlO.0r...

'0-0000 •.

•

1'00001·.

!

ltl o"ooot!

c

o

';

c:

V

\J

C

o

u

Figure 2. Atrazine concentrations (/lglL) over time at the four sampling sites listed. Note vertical

axis is log-scale.

Figure 3. Calcium concentrations (mg/L) over time at the four sampling sites listed.

6
,",un Jul Aug Sep

Date

Dec

-+-Si~5

-o-Site8

--ll~ Sit. 9

---&- Site to

Figure 4. N03+NOz concentrations (mgfL) over time at the four sampling sites listed.

__._Site5

-o-Sitel

~Slteg

-'-Site'O

.....,

Nov De<:

.... . '. ·/~·.··"--'. '/', '/.". >.. . .,,"

'"

8·1 i----l--~--"""----.Ir-: --I---.......-__+

8'0

1·9

7-8

VI 7-7 ..

c 7·6

;;, 7-5

a. 7'4

7-3

7·2

7·1

7·0

6·9 +---....,--~.._- iii

MilY Jun Juf A.ug Sep Oct

Oilt~

Figure 5. pH levels over time at the four sampling sites listed.

7
•

2 .. ' ..• ...../ .._~.. .. ':""

.- . " .....,.. . 1 '" ~~- ~'''-''"--.,---.'''''.--''''._ ... ~-----.--'''''-_.' ..---.,-~',.-''.-.'''''_._-,.-- u __. -,"t'"' .,-....._"~

M~y Jun JUI Aug Sep Oct "'40V Dec

Oate

7 , .

6 if

,.

!

j

T

j

t

-+- Site 5

-0-- Slte 8

-;...- Site 9

-A·- Site 10

Figure 6. Dissolved organic carbon concentrations (mg/L) over time at the four sampling sites listed.

...

c.

::>

o

u

l00CX>O

10000

1000

!

1,

100 .I---.--,........-~-....-~--,..........---..---...-----+-

JU/"l Jul Aug Sep Oct NovOec

Date

Figure 7. Phytoplankton cell counts (cells/L) over time at the four sampling sites listed. Note vertical

axis is log-scale.

8
15 June 9, 1989

10·

'0

<- 1l 15 ........-----------------.....,

E June 23,1989 :l

z 10

15 Sept. 1,1989

10

5

0 2

15

Sept .14, 1989

10

2 7 e 9 10 11

:.L-__.LOl.- ---'l..w...-JLJ._.....u<:L.....l.L<'--lLJ-.....w~ 3 4 5 15

_[La 0 n 1 2 3 4 5 o

5

+

4 5 7 8 9 10 II

9

[1

" FJ" .. a. 2 J

Nov. 16.1989

o

15 15 Aug. 4.1969

! '5~ 27,1989

i '4

oj n 0 fh 0

1 :2 3 <I

!:~ oJ"'::'~9_,._9..Lal-4-JOU~ ~-LU0:LC_t_'--,:,,-'_19_J_8_9.u-.L4L-..L-l-5_-::.D6-C::7-.u'~ ~.-U-9-10 11

t

15·

I 10 Oct. 27, 198

t 5

rL.---U.-~~~~.u..J. !I 6

c::J Di~toms

fZZ!2 Greens

Flagellates

_ Bluegreens

5

10

11

5 G 7 9 10 11

Aug. 18, 1989

10

.~ 5 v

III

0

'0

15

E

i '

:~.~ :2 3 4 5 6 7 8 9 10

Site number

Figure 8. Distribution of plankton groups over all sampling sites on each day ofsampling.

9
Table 1. General descriptions ofsampling locations. (study table 1)

Site number Site description

1-4 Tile drainage outlets

5 Channel carrying tile f10w

6 Branch ofstream post-confluence

7 Branch ofstream post-conf1uence

8 Upstream background site

9 Upstream prior to confluence

10 Downstream after mixing

II Salt Spring Brook

Stream

depth (em)

15

15

10

30

30

20

100

Stream

width (cm)

60

50

50

90

120

80

400

Precipitation

Month (mm)

Table 2. Monthly meteorological data from Havelock, New Brunswick station (approx. 10 km from

site). (study table 2)

Mean temp cae)

Max. Min.

June

July

August

September

October

November

21.2 9.4

24.4 10.3

23.7 11.7

19.3 7.4

13.3 1.9

4 -3.9

64.8

99.8

114.7

88

48.4

153.8

10
Table 3. Summary of water quality data. No units are provided in the original. (study table 3)

Site 5 Site 8 Site 9 Site 10

Parameter Median Min. Max. Median Min. Max. Median Min. Ma."t. Median Min. Max.

Color 12.5 5 80 10 5 30 10 5 40 10 5 30

Turbidity 1.7 0.6 32 0.7 0.4 28 0.4 0.3 30 0.7 0.3 25

Specific conductance 1190 375 1400 441 130 625 675 129 790 740 207 1100

pH 7.8 7.1 8 7.7 7.2 8.1 7.8 6.9 8.1 7.8 7.3 8

Total alkalinity 135 44.9 141 109 31 139 102 32 163 107 34 120

Calcium 200 46 271 58 15 87 86 16 108 112 26 160

Magnesium 29 10 34 12 3.5 15 16 3.3 18 18 5 23

Potassium 1.7 0.9 3.1 1.7 0.87 3.4 1.9 1 2.4 1.9 I 2.3

Sodium 39 10 49 13 4.3 23 20 5 37 27 6.9 40

Chloride 25 12 31 7.4 1.7 14 13 ND 16 16 3.9 23

Sulfate 546 210 758 98 18 220 200 20 266 280 44 440

Silica 27 9.8 30 12 8.6 15 13 7 15 16 1.4 20

Dissolved organic carbon 1.6 1.2 9.6 2.9 2.2 6.2 2.9 2.1 6 2.6 1.5 6.6

N03+N02 0.07 ND 3 0.11 ND 0.88 0.08 ND 0.9 0.08 ND 1.2

Total nitrogen 0.28 ND 4.4 0.36 0.13 1.4 0.3 0.13 1.6 0.27 0.15 2

Note: ND = not detected

11
Table 4. Atrazine concentration measurements in /-lg/L. "-" notation is not defined in the original.

(from study table 5)

Collection Sampling site

Date 1 2 3 4 5 6 7 8 9 10 /J

9-Jun-89 5.756 6.334 0.009 20.39 13.9 1.891 0.224 0.169 0.255 1.7 0.2

23-Jun-89 0.014 0.003 0.166 1.72 6.36 1.53 0.077 0.023 0.051 0.2 0.16

7-Jul-89 0.003 0.033 0.002 0.125 0.21 0.167 0.029 0.009 0.021 0.078 0.009

21-Jul-89 0.007 0.046 0.015 0.112 0.889 1.04 0.047 0.016 0.024 0.205 0.011

4-Aug-89 0.044 0.018 0.073 0.379 0.431 0.038 0.007 0.011 0.181 0.008

18-Aug-89 0.043 0.072 0.079 0.464 0.886 0.026 0.01 0.017 0.271 0.013

I-Sep-89 0.035 0.006 0.032 0.231 0.172 0.013 0.005 0.007 0.007 0.007

14-Sep-89 0.003 0.005 0.211 0.22 0.016 0.008 0.555 0.004

5-0ct-89 0.19 0.965 0.414 0.375 0.961 0.91 0.001 0.001 0.001 0.1 0.014

27-0ct-89

16-Nov-89

Table 5. Phytoplankton cell counts. "-" notation is not defined in the original. (from study table 5)

Collectio Sampling site

n 1 2 3 4 5 6 7 8 9 ]0 11 Date

9-Jun-89 1,79 1,06 650 9,980 14,040 33,44 78,200 90,060 7,560 2,710 0 0 0

23-Jun- 510 570 290 890 840 11,050 17,83 87,680 100,71 25,460 19,180 89 0 0

7-Jul-89 180 580 890 230 420 3,960 9,990 41,750 53,260 16,770 27,500

21-Jul-89 120 310 820 4,23 240 360 2,320 39,000 33,580 7,680 6,030 0

4-Aug-89 750 7,10 760 6,980 43,170 22,69 47,520 66,210 102,67 9,210 0 0 0

18-Aug- 150 2,56 2,31 820 13,26 4,460 62,200 24,700 20,630 14,170 89 0 0 0

I-Sep-89 2,26 790 9,770 12,030 42,75 88,910 123,09 152,98 51,060 0 0 0 0

14-Sep- 28 61,77 130,93 30,75 111,00 151,04 69,500 141,81

89 0 0 0 0 0 0

5-0ct-89 870 790 2,63 12,65 225,22 23,73 165,80 133,89 23,180 58,140 0 0 0 0 0 0

27-0ct- 290 790 52,88 64,610 85,51 90,050 116,90 46,280 31,630 89 0 0 0

16-Nov- 760 560 1,42 570 43,55 82,22 66,310 85,070 44,720 25,560 89 0 0 0

12
Table 6. Number of phytoplankton species in water samples. "- " notation is not defined in the

original. (from study table 6)

Collection Sampling site

Date 1 2 3 4 5 6 7 8 9 10 11

9-Jun-89 3 2 3 9 8 8 10 12 7 3

23-Jun-89 2 2 1 1 2 6 5 13 13 4 5

7-Jul-89 1 2 4 1 1 4 3 10 14 4 3

21-Jul-89 2 2 3 2 3 1 3 11 8 4 4

4-Aug-89 2 4 1 4 7 5 8 10 10 5

18-Aug-89 2 2 1 5 3 8 8 4 4

I-Sep-89 2 1 4 4 9 10 10 8 9

14-Sep-89 6 7 5 8 9 9 10

5-0ct-89 2 3 2 13 7 12 9 4 8

27-0ct-89 1 1 8 11 11 12 15 13 13

16-Nov-89 1 2 4 1 16 12 10 12 12 11 11

Table 7. Number of phytoplankton species in net samples. "- " notation is not defined in the

original. (from study table 6)

Collection Sampling site

Date 1 2 3 4 5 6 7 8 9 10 11

9-Jun-89 5 2 3 6 10 10 13 17 18 8 10

23-Jun-89 4 ,.,

-' 1 3 4 14 9 19 21 8 9

7-Jul-89 2 3 5 3 5 6 7 16 19 11 13

21-Jul-89 ,.,

-' 3 5 5 4 4 4 16 14 7 8

4-Aug-89 7 7 10 7 14 11 17 14 14 12

18-Aug-89 4 5 6 ,.,

.J 11 9 7 19 17 9 13

I-Sep-89 3 6 3 8 7 15 14 17 9 15

14-Sep-89 2 3 12 15 14 19 14 15 19

5-0ct-89 4 3 1 4 10 16 14 19 14 14 14

27-0ct-89 2 2 1 2 13 12 16 16 22 28 22

16-Nov-89 1 3 6 4 19 19 14 20 19 17 16

13
Data Summary Table:

Effect Magnitude of Nominal Day of Time Did Recovery Comments

Effect relative Atrazine Study Effect Weighted Occur - Ifso,

to controls Concentratio Occurred Average when (see

n (J.1g/L) Atrazine comment)?

Concentratio

n from Day 0

to When

Efject

Occurred

Comparison of

no (>166 Site 5 (nearDecline in not applicable 48 (day of days; partial field stream)

phytoplankton >99% (4 Llha to tile maximum 5.3 Ilg/L to Site 8

(cell counts) plots) effect) recovery (background noted) site). See

Table 5.

Comparison of

Decline in Site 5 (nearphytoplankton not applicable 34 (day of field stream)

(number of 90% (4 Llha to tile maximum 6. I Ilg/L yes (Day 166) to Site 8

species)1 plots) effect) (background

site). See

Table 6.

Time weighted averages were calculated from the atrazine concentration time series.

Each data point was assumed to apply to the time interval starting at the midpoint ofthe

time period since the last measurement, and ending at the midpoint ofthe time period

until the next measurement. Time periods between measurements were all 14 days. The

first data point covered the time period beginning at atrazine application, and the last data

point covered only the previous 7 days. See below for calculations (linked to Excel

spreadsheet).

I Ibid.

14
Atrazine cones

Date Site 5 Days coverage ( Day-weight

9-Jun-89 13.9 10 139

23-Jun-89 6.36 14 89.04

7-Jul-89 0.21 14 2.94

21-Jul-89 0.889 7 6.223

TWA 21 July

TWA 7 July

5.271178

6.078421

Reviewer Comments:

This study was a set of observations of a single, natural stream during a single year. The

object, apparently, was to evaluate effects on this stream of known atrazine additions on a

systematic setup oftile plot with known drainage. However, the plot-specific drainages

(from Sites 1-4) were not analyzed, and instead the focus was on downstream sites where

confounding was likely due to confluence with larger streams that were affected by

dynamics elsewhere in the watershed. Background levels of atrazine were well above the

detection limit in the "control" locations, and the authors discuss at length the issue of

groundwater flow affecting water quality parameters (nutrient levels) that could in turn

affect phytoplankton populations (the endpoint of interest). Moreover, the sampling

design failed to observe baseline conditions prior to atrazine addition. Indeed, sampling

did not begin until three days after the atrazine application, and in that intervening time

there was a significant amount ofrainfall (16.6 mm). The most acute effects may

therefore may have been missed due to the sampling approach.

In terms of presentation and data analysis, when citing numbers, the units associated with

those quantities must be provided in order for the data to be interpreted correctly, but in

the water quality table as well as the description ofrainfall in the text, no units were

provided. The methodology of atrazine application, including the product used, was not

discussed. Finally, there was no data analysis: near-raw data were provided in tables and

graphs and then discussed in a visual or general way, but no statistics or analyses was

done to quantify the assertions and provide them with objective support. For example,

the authors state that the phytoplankton time-series "appear[s] to coincide" with the

atrazine time-series, but the reviewer did not necessarily agree after visually examining

the plots and found the judgment subjective.

Description of Use in Document (QUAL, QUAN, INV): INV

Rationale for Use: Study limitations described below limit the utility ofthe study. The

system tested was a natural system with drainage from agicultural areas. The presence of

other pesticides is likely to have occurred. Also, atrazine was detected in controls at

levels that could influence the results.

15
Limitations of Study: This was an uncontrolled, once-off field experiment. Although

the authors assert that their findings are evidence of mild, transient downstream effects on

phytoplankton communities, they provide no quantitative support for their conclusion,

and there are potentially significant confounders such as nitrate fluctuations and timevarying upwelling of groundwater through a gypsum-rich substrate. Additionally, results

are limited by the fact that sampling began three days after atrazine addition to the field

plots, with no preliminary sampling to determine baseline conditions.

Primary Reviewer: Sara Hendrix, M.S., Staff Scientist, Cambridge Environmental Inc

,1/

Secondary Reviewer: Brian Anderson, U.S. EPA I'

16