Open Literature Review Summary

Chemical Name: Atrazine

CAS No: 1912-24-9

ECOTOX Record Number and Citation:

Hamilton, P.B., D.R.S. Lean, G.S. Jackson, N.K. Kaushik, and K.R. Solomon. 1989.

The effect oftwo applications ofatrazine on the water quality offreshwater enclosures.

Environ. Pollut. 60:291-304 (MRID 47543501).

Purpose of Review:

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

study contribute to the weight-of-evidence regarding effects of atrazine on aquatic plant

communities and associated determination of a Level ofConcern (LOC).

Date of Review:

November 24, 2009

Purpose of Study:

This study is a companion paper to Hamilton et aI., 1988 and examines the potential

effects oftwo atrazine applications to water quality changes in experimental enclosures in

a natural lake. The persistence and effects of atrazine on forms of nitrogen, phosphorus,

chlorophyll, and carbon were monitored. The balance between autotrophic and

heterotrophic activity was assessed by comparing oxygen concentration in treated and

non-treated enclosures.

Summary of Study Findings:

Methods: The basic experimental design ofthis study is also reported in Hamilton, et at.

(1987) (1983 study), Hamilton, et ai. (1988), and Herman, et ai. (1986).

The study was conducted in Lake 81. George, Canada, a 10-ha mesotrophic, dimictic lake

(geographic coordinates are provided, but surrounding land use is not described). 5 m x

5 m enclosures made of nylon reinforced polyvinyl chloride (PVC) were installed to a

depth of4.5 m (the lake bottom). The enclosures were acclimated to Lake St. George

water for at least 6 months. The experiment took place from May 1983 to April 1984.

Three enclosures were used as controls (C1, C2, and C3) and three were used for atrazine

treatment (A 1, A2, and A3), treated twice with commercially available atrazine (80%

11••111111

2087859 ---------_..._-- ------ ------
active ingredient, manufacturer not provided). On June 1, 1983, a nominal concentration

of 0.1 mg/L (100 /lg/L) was applied to the water surface with a backpack sprayer, and the

same quantity water applied again 35 days later, on July 6, 1983. Sampling and analysis

of atrazine in the enclosures are not described, and the reader is referenced to a related

1981 paper; analysis was performed by the Ontario Ministry of Agriculture and Food.

Water quality samples were taken weekly during the summer of 1983, starting 3 weeks

before the first application of atrazine. All sampling took place between 9 a.m. and 5

p.m. using a raft with a walkway hanging over the enclosure. Temperature and dissolved

oxygen profiles were taken to 3.5 m depth using a YSI Model 57 oxygen-temperature

meter. Eight integrated water samples were collected from preselected random locations

in each corral, the same location in each corral on a given sampling day. The integrated

samples were combined, thoroughly mixed, and two subsamples taken for phytoplankton

analysis, as described in Hamilton, et at. (1988), and water chemistry. The 2-L water

chemistry sample was subdivided and analyzed for: nitrate, nitrite, ammonium, Kjeldahl

nitrogen (TKN), particulate nitrogen (PN), soluble reactive phosphorus (SRP), total

phosphorus of filtered water (TP), dissolved inorganic carbon (DIC), dissolved organic

carbon (DOC), particulate organic carbon (POC), and the major ions Ca, Na, K, Cl, and

S04. Secchi disk measurements were taken at the center of each enclosure after all other

field data were collected. Chemical analyses were performed by the Canadian Centre for

Inland Water using the standard methods of Environment Canada, 1979.

Since exchange with lake water for nutrient input was prevented by the enclosures,

reagent grade NaNO} and analytical grade H3P04were added to each corral each week

from Day -22 to Day 76, at a loading equivalent of 13.0 g N/m2

/yr and 1.0 g P/m2/yr.

Leaks were checked for by divers as well as by comparing the theoretical rate of Na

increase (20 /lg/Llwk) to the observed rate. The study ended 323 days after the initial

application of atrazine, and there were 21 sampling dates in total.

Primary production was measured by 14C uptake. 2.51lCi 14C-bicarbonate (New England

Nuclear) was added to 1 L composite samples obtained from 1 m depth. Bottles were

then resuspended at 1.5 m until 0.25 Einsteinsll OOOce ofphotosynthetically active

radiation (PAR) had been reached (usually 1-2 hours). Samples were collected on

Millipore cellulose acetate filters (5.0 and 0.22 /lm), decontaminated by rinsing with 5

mL 0.1 N HC]), and radioassayed by liquid scintillation using Aquasol II. Replicate

samples were within 5%.

A two-tailed Student's t test was used to test for significant (p<0.05) differences between

control and treatment enclosures on each sample date. Data were not pooled over sample

dates because ofstrong seasonal changes. The data were acceptably normal and of

homogeneous variance without transformation (no description oftests used).

2
Results: The results presented in the article are not redundant with any results described

in the related articles, Hamilton, et al. (1987) (later study), Hamilton, et al. (1988), and

Herman, et al. (1986), with the exception of atrazine concentrations, which are also

reported in Herman, et al. (1986).

Atrazine was evenly distributed throughout the water column after 2 days. Initial mean

concentration of atrazine in the treatment enclosures was 0.11 mg/L (110 11gIL), with a

standard deviation of 0.020 mg/L (20 IlglL). Losses in enclosures A2 and A3 were

negligible, but 0.04 mg/L (40 Ilg/L) was removed from Al over the first 35 days. After

the second application, which was expected to double the atrazine concentration, instead

there was a 50% increase, and after Day 36 the atrazine level declined more rapidly with

a half-life of 150 days. See Figure 1 for a time series of atrazine concentrations.

Temperature profiles were similar in all the enclosures throughout the study.

Pretreatment temperatures went from 5.8-6.2°C (bottom-surface) in April, to 10.5-15.1 °C

in May, and by the end of May, a thermocline was evident between 2.5 and 3 m depths.

After treatment (Days 0-98, June-August), temperatures ranged from 13.0°C (bottom) to

24.5°C (surface), with a thermocline between 3 and 4 m depths. From September to

November (Days 99-160), water temperatures in the enclosures dropped for 6.0°C with

the thermocline disappearing late in September. As the water warms in the spring in

Lake 81. George, calcium carbonate usually precipitates. The first application of atrazine

did not affect this process, but after the second application, calcium carbonate

precipitation was suppressed. As a result, Ca and DIC concentrations remained higher in

the atrazine treatment enclosures. The following spring, Ca and DIC levels were similar

in all enclosures. See Figure 2.

Chlorophyll a measurements were highly variable, with coefficients of variation (CVs)

ranging from 5.7-162.5%, which precluded statistical significance in the treatment

differences. Primary production was measured within hours ofthe second atrazine

addition, and the photosynthetic rate was not normalized to chlorophyll a because ofthe

lack of precision in the latter measurements. Figure 3 shows the primary productivity

estimates both with and without correction for particulate carbon and algal biomass.

Inhibition of J4C uptake (43%) was observed hours after the second addition, with further

reductions to 20% of control values over the next 22 days. Production per unit particulate

carbon concentration was also lower in the atrazine-treated enclosures, but production per

unit algal biomass, though quite variable, did not change significantly in the treatment vs.

control enclosures. DOC and POC levels were reduced after atrazine treatment relative

to controls, with significant differences (p<0.05) on Day 34, 69, 76, and 99 (see Figure

2), but recovered the next spring. Sulfate concentrations were consistently higher in

atrazine treatment enclosures, with significant differences (p<0.05) on Days 34, 54, and

97 (Figure 2).

3
Dissolved oxygen concentrations (Figure 1) at 0.5 m depth were consistently lower after

the first application of atrazine, with Day 0-35 average concentrations of 10.8 ± 0.6 mg/L

and 9.5 ± 1.0 mg/L in control and treatment enclosures, respectively, which were not

statistically significant (p>0.05). Corresponding concentrations after the second atrazine

application were 10.3 ± 0.5 mg/L and 8.1 ± 0.3 mg/L, respectively, with significant

differences (p<0.05) occurring between Days 34-98. No differences were found on Day

323 at either depth. No significant differences were found at 3.5 m depth, but there was

large variation among replicates (CY 2.7-46.2%).

Particulate nitrogen levels were generally lower in the treatment enclosures, but the

difference was only statistically significant on Day 41, which was 5 days after the second

atrazine application (see Figure 4). TKN was higher in treatment enclosures after the

second atrazine applications, mostly due to ammonium concentrations, but no significant

trend was detected (Figure 4). Ammonium, nitrite, and nitrate+nitritc concentrations

were also higher in the treatment enclosures, especially after the second atrazine

application, with significant differences on Day 112, 125, and 323 (Figure 4).

With the weekly addition ofsodium in the NaN03, sodium concentrations linearly

increased in all the enclosures, until Day 76 when NaNO} addition ceased (Figure 2).

Afterwards, they stabilized and declined over the winter. The authors speculate that the

spike of Day 34 is due to analytical error. Other major ions (Cl, K, Mg) were not altered

after atrazine application (Table 1). Silicon and Secchi depth measurements were highly

variable and were not analyzed, but Secchi disc readings in the treated enclosures

averaged 3.6 m instead ofthe 2.9 m ofthe controls, and greater clarity in the treatment

enclosures was visible.

The authors also discuss the possibility of photodegradation or adsorption ofthe atrazine

as removal processes. Both diving and Na analysis agreed that atrazine was not being

removed due to enclosure leakage.

There were some artifacts due to enclosure. Lake concentrations ofDIC, Mg, Ca, Si02

and chlorophyll a were significantly higher than control corral levels, with no difference

in TKN, total phosphorus (filtered), SRP, K, DOC, POC, and PN (unpublished data).

Also, there were slightly higher oxygen levels (0.4-2.0 ppm), which may be an indirect

indicator of periphyton on the enclosure walls.

4
ATRAZINE

02

01

a::

... «

0.0

0

14

20 40 60 eo 100

OXYGEN {O.S m)

.. Ca.1lU

.... "lH.b.tf\E

i 10

9:

z

tU

'-'

,. ij

x

o

2 r~~

.20 30 80 130 :l30

TREATMENT DAYS

Figure 1. Mean atrazine concentrations in treated enclosures and mean oxygen levels at 0.5 and 3.5

m depths in both atrazine and treated enclosures. Applications were on June 1 (Day 0), represented

by a single arrow, and on July 6 (Day 35), represented by a double arrow. Vertical bars,

representing one standard deviation, are shown for day with significant (p<0.05) differences.

5
r SODIUM

91

I • 11...( ;'.

J I'

I i y~7:'"~. 6

4

1

J;/~"" .... >-""'i t I

5 -1 I I I I .t-r-

-20 0 20 40 60 80 lOO 120 320

TREATMENT

\.... ." ",':-. L.~' .,.~•• , '1--1 •••• i ''''f'-

o ',. t I *1 r T ........,T.......,~ ... ;-....-

-20 0 2.0 40 60 80 100 120 320

DAYS AFTER

eo

CALCIUM

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~. 6Q

so .....

O'l 40

E 30

Drc

Z 4!>

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<: 35 IX

....

Z

LU 2S U

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Figure 2. Mean concentrations of calcium, sulfate, dissolved inorganic carbon (DIC), dissolved

organic carbon (DOC), particulate organic carbon (POC), and sodium, in control (solid) and atrazine

(dashed) enclosures. Treatment days are presented by single and double arrows. Concentrations are

expressed in mg/L with vertical bars representing one standard deviation presented on days with

significant (p<O.OS) differences.

6
c

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o+--~._-;:-1_..:;;.---..i~J ..0.,..-------------------.....,

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37 46 57 74 102 1.35 390

DAVS AFTER TREATMENT

Figure 3. Primary production (Ilg CIL/Einstein), upper panel. Primary production was normalized

to give the per cent specific activity (SA) for particulate organic carbon (100 x primary

production/POC), middle panel, and for algal biomass (100 x primary production/biomass), bottom

panel. Control enclosures are represented by open dots and treatment enclosures are represented by

closed (solid) squares. Double arrow indicates second atrazine application. Note that the time axis is

scaled by equal breaks between measurement days and is not time-scaled.

7
.03

.01

AMMONH,JM

.01

.01 ~.

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NITRITE

DAYS AFTER TREATMENT

Figure 4. Mean concentrations of ammonium, nitrite, nitrate+nitrite, particulate nitrogen (PN), and

total phosphorus from filtered and unfiltered water, in control (solid) and atrazine-treated (dashed)

enclosures. Treatment days are indicated by single and double arrows. Concentrations are in mg/L,

with vertical bars representing one standard deviation presented on days with significant (p<O.OS)

differences.

8
Table 1. Summary of nutrient and ion data where one or no significant (p<O.05) differences were found between treatments. The seasonal means,

range (minimum-maximum), and coefficient of variation (CV) range (lowest-highest) are presented. All except Secchi depth (m) are in mg/L.

Contrf!1 Atrazine

Mean Minimum Maximum lowest highest Mean Minimum Maximum lowest highest

CV CV CV CV

TKN 0.67 0.444 0.871 5.8 21.7 0.696 0.382 0.896 1.8 22.4

SRP 0.0018 0.0012 0.0035 5.5 111 0.0014 0.0009 0.0028 7.7 78.9

SiOz 1.75 0.93 3.95 9.4 80.9 1.46 0.69 3.65 19.1 99.7

Cl 11.58 11.01 11.88 0.5 4 11.47 10.98 11.84 0 1.3

Mg 6.72 5.71 7.18 0.9 6.6 6.78 5.88 7.1 0 7.1

K 2.31 2.2 2.43 0.4 4.1 2.31 2.11 2.46 0.3 3.1

Secchi 2.9 1.1 3.8 11.2 52 I 3.6 1.2 4.5 0 27.3

Chloroohyll 3.4 0.6 16 20.6 142.9 2.5 0.2 15.9 5.7 162.5

9
Data Summary Table:

('ommen" l ,..----'----.--r-:-:-~-.--.,......-'---~1: Effect Magnitude of Nominal Day of

Effect Atrazine I Study Effect

relative to Concentration Occurred

controls (pg/L)

Time Did

Weighted Recovery

Average Occur - if

Atrazine so. when

Concentration (see

pom Day () to comment)?

I When E.'flect i !

I D,cr,ase ;n 40% I OC'"'=-r""~-~gnitudes II

partic~Jate (significant 100 J.lg/L I' Day 34 I05.6I.lg/L 9ges - Day 'I e:s~timat.Cd I

I orgamc 0 'fF 2 ' carbon at p< .05) --L ~om 19. j

Decrease in (IS~~::d/L I J-8_/~1_~;es '" Day I M~g~~ddeS primary,. I, 800 /

0 D 57' , t t

productIvity! /( treatment ay 1'-' ~lg 1,,~35 -r! ,,~~O:,,~i~.3 (

14C uptake)-l- Day 35), -i'r-~

I'MOI l00l.lgiL I --, - Increase in ,100% I_"! I Magnitudes

nitrate+nitrite II (significant ~:~t~~~nt Day I Day 110 I J 04.5 I.lg/L I No I estimated

concentration at p<0.05) 35) " i from Fig 4

~ecrease in 1 25% I ~-~',~ ~- Yes - Da;,'Magnitu~es dIssolved, (. '1- t ]00 'L I nD "4 1056 'L 323 (t . d slgm Ican flgi I' ay.) . flg! 'nex, estimate

oxygen (0.5 i at p<O 0';) , 'spring) I' from Fig'.! ~~2_" I •.

In.crease in 1°0/0 100 J.lg/L I' Y D ! M . d /( es ay 1" agmtu es

dissolved (significant (second Day 45 J 13.7 "giL 323 (next estimated

inorganic

°5 treatment E r I carbon i at p< .0) i Day 35) spring) ! from Fig.2

1

Increase In 130% noo J.lg~L '" Yes - Day

calcium '(significant! (tsecton t D I Day 45 113.7 I.lg/L 323 (next estimated . , rea men ay concentratlOn I at p<0.05) I 35) spring) from Fig.2

Bolded values are those data points specified in the "Cosm Data Points and Exposure Profiles" spreadsheet.

Time weighted averages were calculated from the atrazine concentration measurements,

as estimated from Fig.I. A full daily chemograph was constructed assuming linear

changes between each measurement point, and time weighted averages were computed as

a simple cumulative average over all days' concentrations. For extrapolation beyond the

last measurement day, a constant rate of decline was assumed based on the last interval.

See linked Excel table, below. In the table, blue highlighted cells are values estimated

from Fig.l, and yellow highlighted cells are TWAs needed for the Data Summary Table.

Day Cone. TWA

o 110 110.0

1 110 110.0

2 110 110.0

3 110 110.0

4 110 110.0

5 110 110.0

6 110 110.0

7109.8571 110.0

10
8 109.7143 110.0 9 109.5714 109.9

10 109.4286 109.9

11 109.2857 109.8

12 109.1429 109.8

13 109 109.7

14 108.6667 109.6

15 108.3333 109.6

16 108 109.5

17 107.6667 109.4

18 107.3333 109.3

19 107 109.2

20 105.7778 109.0

21 104.5556 108.8

22 103.3333 108.6

23 102.1111 108.3

24 100.8889 108.0

25 99.66667 107.7

26 98.44444 107.3

27 97.22222 107.0

28 96 106.6

29 97.42857 106.3

30 98.85714 106.0

31 100.2857 105.9

32 101.7143 105.7

33 103.1429 105.7

34 104.5714 105.6

35 106 105.6

36 116.5 105.9

37 127 106.5

38 137.5 107.3

39 148 108.3

40 148.75 109.3

41 149.5 110.2

42 150.25 111.2

43 151 112.1

44 149.1818 112.9

45 147.3636 113.7

46 145.5455 114.3

47 143.7273 114.9

48 141.9091 115.5

49 140.0909 116.0

50 138.2727 116.4

51 136.4545 116.8

52 134.6364 117.1

53 132.8182 117.4

54 131 117.7

55 130.5 117.9

56 130 118.1

57 129.5 118.3

11
58 129 118.5

59 128.5 118.7

60 128 118.8

61 127.5 119.0

62 127 119.1

63 126.5 119.2

64 126 119.3

65 125.5 119.4

66 125 119.5

67 124.5 119.6

68 124 119.6

69 123.5 119.7

70 123 119.7

71 122.5 119.8

72 122 119.8

73 121.5 119.8

74 121 119.8

75 120.5 119.8

76 120 119.8

77 117.125 119.8

78 114.25 119.7

79 111.375 119.6

80 108.5 119.5

81 105.625 119.3

82 102.75 119.1

83 99.875 118.9

84 97 118.6

85 94.125 118.4

86 91.25 118.0

87 88.375 117.7

88 85.5 117.3

89 82.625 117.0

90 79.75 116.6

91 76.875 116.1

92 74 115.7

93 71 125 115.2

94 68.25 114.7

95 65.375 114.2

96 62.5 113.7

97 59.625 113.1

98 56.75 112.5

99 53.875 111.9

100 51 111.3

101 48.125 110.7

102 45.25 110.1

103 42.375 109.4

104 39.5 108.8

105 36.625 108.1

106 33.75 107.4

107 30.875 106.7

12
108

109

110

28

25.125

22.25

106.0

105.2

104.5

Reviewer Comments:

This study is the last (most recent) citation from the Herman/Hamilton, et al., group on

the Lake St. George enclosure studies from 1982/1983. It focuses primarily on water

quality measures, with some examination of 14C uptake productivity. In general, the data

are well presented, with many straightforward time series figures and basic statistical

analyses performed for significance detection. Although only one atrazine treatment

level is examined,J replicates for treatments and controls in a semi-natural experimental

setting provide a somewhat reasonable sample size for statistical analysis.

Some aspects ofthe methodology were not fully explained within the article. The

manufacturer ofthe commercial atrazine product was not mentioned. The land use

characteristics ofthe Lake St. George watershed, and the presence or absence of

background levels of atrazine in the lake, were not described. For atrazine analysis as

well as chlorophyll a and algal biomass analysis, the authors provided references but did

not summarize the methodology.

As discussed by the authors themselves, there were some enclosure effects that

potentially influenced the results. The nutrient levels were somewhat artificial due to the

need to provide external Nand P inputs. The enclosure walls provided sheltered surfaces

for periphyton colonization and induced a lack of lateral water exchange within a

reasonably tall (4.5 m) water column that is not realistic in a natural lake setting.

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

Rationale for Usc: Results confirm that a decrease in primary production (via 14C

uptake) accompanied a shift in periphtyon community structure following two

applications of atrazine (35 days apart) at 100 IlgiL.

Limitations of Study: With the exception ofthe primary production ('4C) endpoint, all

other reported endpoints were abiotic. Artifacts (particularly in nutrient levels) may have

occurred due to enclosure effects. Other study limitations, which are noted in the

Reviewer's Comments, include analysis of only one atrazine treatment, insufficient

description of potential background contamination in the control enclosures, and

confounding effects associated with the lack of lateral water exchange and periphyton

colonization due to the sheltered surfaces ofthe enclosure walls.

13
Primary Reviewer: Sara Hendrix, M.S., Staff Scientist, Cambridge Environmental Inc

Secondary Reviewer: Anita Pease, M.S., Senior Biologist, Environmental Fate and

Effects Division, U.S. Environmental Protection Agency.M,>t- (..(t~(U

14