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

Purpose ofReview: Determine potential effects ofatrazine on an aquatic community. Endpoints from this study contribute to the weight-of-evidence regarding effects ofatrazine on aquatic plant communities and associated determination ofaLevel ofConcern (LOC).

Date ofReview: November 24, 2009

Purpose ofStudy: This study is a companion paperto 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 ofatrazine on forms ofnitrogen, phosphorus, chlorophyll, and carbon were monitored. The balancebetween autotrophic and heterotrophic activity was assessedby comparing oxygen concentration in treated and non-treated enclosures.

Summary ofStudy Findings:

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

### et

## at. (1987) (1983 study), Hamilton, 

### etai. (1988), and Herman, 

### etai. (1986).

The study was conducted in Lake 81. George, Canada, a 10-hamesotrophic, dimictic lake (geographic coordinates are provided, but surrounding landuse is not described). 5 m x 5 m enclosures made ofnylon reinforced polyvinyl chloride (PVC) were installedto a depth of4.5 m (the lake bottom). The enclosures were acclimatedto Lake St. George water for atleast 6 months. The experiment tookplace 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), treatedtwice with commercially available atrazine (80%



# 11••111111 2087859

--- --- ---_

..._--

------

------active ingredient, manufacturernotprovided). On June 1, 1983, a nominal concentration of0.1 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 ofatrazine in the enclosures are not described, and the reader is referencedto arelated 1981 paper; analysis was performed by the Ontario Ministry ofAgriculture and Food.

Waterquality samples were taken weekly during the summer of1983, starting 3 weeks before the first application ofatrazine. All sampling took place between 9 a.m. and 5 p.m. using araft with a walkway hanging overthe enclosure. Temperature and dissolved oxygen profiles weretaken 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 offiltered 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 centerofeach enclosure after all other field data were collected. Chemical analyses were performed by the Canadian Centre for Inland Waterusing the standard methods ofEnvironmentCanada, 1979.

Since exchange with lake water for nutrient inputwas preventedby the enclosures, reagent grade NaNO} and analytical grade H3P04were addedto each corral each week from Day -22 to Day 76, at a loading equivalent of13.0 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 ofNa increase (20 /lg/Llwk) to the observedrate. The study ended 323 days afterthe initial application ofatrazine, 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 mdepth. Bottles were then resuspended at 1.5 m until 0.25 EinsteinsllOOOce of photosynthetically 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 scintillationusing Aquasol II. Replicate samples were within 5%.

A two-tailed Student's ttestwas used to test for significant (p<0.05) differences between control and treatmentenclosures on each sample date. Datawere notpooled over sample dates because ofstrong seasonal changes. The data were acceptably normal and of homogeneous variance withouttransformation (no description oftests used).

2Results: The results presented in the article are notredundant with any results described in the related articles, Hamilton, 

### etal. (1987) (later study), Hamilton, 

### etal. (1988), and Herman, 

### etal. (1986), with the exception ofatrazine concentrations, which are also reported in Herman, 

### etal. (1986).

Atrazine was evenly distributed throughout the water column after2 days. Initial mean concentration ofatrazine in the treatmentenclosures was 0.11 mg/L (110 11gIL), with a standard deviation of0.020 mg/L (20 IlglL). Losses in enclosures A2 and A3 were negligible, but 0.04 mg/L (40 Ilg/L) was removed from Al overthe first 35 days. After the second application, which was expected to double the atrazine concentration, instead there was a 50% increase, and afterDay 36 the atrazine level declined more rapidly with
ahalf-life of150 days. See Figure 1 for atime series ofatrazine concentrations.

Temperature profiles were similarin all the enclosures throughout the study. Pretreatmenttemperatures went from 5.8-6.2°C (bottom-surface) in April, to 10.5-15.1 °C in May, and by the end ofMay, athermocline was evidentbetween 2.5 and 3 m depths. Aftertreatment (Days 0-98, June-August), temperatures ranged from 13.0°C (bottom) to 24.5°C (surface), with athermocline between 3 and 4 mdepths. From Septemberto November (Days 99-160), watertemperatures 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 ofatrazine did not affectthis process, but afterthe second application, calcium carbonate precipitation was suppressed. As aresult, 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 ofvariation (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 lackofprecision in the lattermeasurements. Figure 3 shows the primary productivity estimates both with and withoutcorrection forparticulate carbon and algal biomass. Inhibition ofJ4C uptake (43%) was observed hours afterthe second addition, with further reductions to 20% ofcontrol values overthe next 22 days. Production perunitparticulate carbon concentration was also lowerin the atrazine-treated enclosures, butproductionper unit algal biomass, though quite variable, did not change significantly in the treatment

### vs. control enclosures. DOC and POC levels were reduced afteratrazine treatmentrelative to controls, with significant differences (p<0.05) on Day 34, 69, 76, and 99 (seeFigure 2), butrecovered 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).

3Dissolved oxygen concentrations (Figure 1) at0.5 mdepth were consistently lower after the first application ofatrazine, with Day 0-35 average concentrations of 10.8 ± 0.6 mg/L and 9.5 ± 1.0 mg/L in control and treatmentenclosures, respectively, which were not statistically significant(p>0.05). Corresponding concentrations afterthe 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 eitherdepth. No significant differences were found at 3.5 m depth, butthere was large variation among replicates (CY 2.7-46.2%).

Particulate nitrogen levels were generally lowerin the treatment enclosures, butthe 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 afterthe second atrazine applications, mostly due to ammonium concentrations, butno significant trend was detected (Figure 4). Ammonium, nitrite, and nitrate+nitritc concentrations
were also higher in the treatment enclosures, especially afterthe 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 overthe winter. The authors speculate thatthe spike ofDay 34 is due to analytical error. Othermajorions (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, andgreater clarity in the treatment enclosures was visible.

The authors also discuss the possibility ofphotodegradation or adsorption ofthe atrazine
as removal processes. Both diving and Na analysis agreed that atrazine was notbeing removed due to enclosure leakage.

There weresome artifacts due to enclosure. Lake concentrations ofDIC, Mg, Ca, Si02 and chlorophyll 

### a were significantly higherthan 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 (0.4-2.0ppm), which may be an indirect indicatorofperiphyton on the enclosure walls.

4ATRAZINE 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 shownfor day with significant (p<0.05) differences.

5r SODIUM 9

# 1

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 70

# ~. 6Q
so



### ..... O'l 40 E 30 Drc 

### Z 4!> 

### 0
I- 

### <: 35 IX



## .... Z LU 2S U 

### Z 

### 0 3 

### poc U

Figure 2. Mean concentrations ofcalcium, sulfate, dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), particulate organic carbon (POC), and sodium, in control (solid) and atrazine (dashed) enclosures. Treatmentdays 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.

6c

I 

# • I I (} 

# • I 8 o

## +--~. _-;:-1

## _..:;;.---..i~J



## ..0.,..-------------------....., 

# ::**,...·-·-g---O------------·~:--·1**

CD**2'~'~** U 01 ::::l.. H;'l

30



## •

<10 • o 

### •



## • Q 

## e 

# •
o 

# • {) 

### •


### • o 

# •
37 46 57 74 102 1.35 390
DAVS AFTER TREATMENT

Figure 3. Primary production (Ilg CIL/Einstein), upperpanel. Primary production was normalized to give the percent specific activity (SA) for particulate organiccarbon (100 xprimary production/POC), middlepanel, 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 measurementdays and is nottime-scaled.

7.03
.01 AMMONH,JM

.01

.01**~.**

I) NITRITE



### DAYS AFTER TREATMENT

Figure4. Mean concentrations ofammonium, nitrite, nitrate+nitrite, particulate nitrogen (PN), and total phosphorus from filtered and unfiltered water, in control (solid) and atrazine-treated (dashed) enclosures. Treatmentdays 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.

8Table 1. Summary ofnutrient and ion data where one or no significant (p<O.05) differences were found between treatments. The seasonal means, range (minimum-maximum), and coefficient ofvariation (CV) range (lowest-highest) arepresented. 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 9g es

- Day 'I

## e:s~timat.Cd I I orgamc 0 'f F 2 '

carbon at p< .05) 

# --L**~om** 19. j Decrease in

# (IS~~::d/L IJ-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 J04.5 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 atp< .0) i Day 35) spring) ! from Fig.2

1 Increase In 130% 

# n oo

## 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 Boldedvalues are those datapoints specified in the "Cosm DataPoints 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 measurementpoint, and time weighted averages were computed as a simple cumulative average over all days' concentrations. Forextrapolation beyond the last measurement day, a constantrate ofdecline 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

108 109.7143 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

1158 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

12108 109 110 28 25.125

22.25 106.0 105.2 104.5

Reviewer Comments: This study is the last (mostrecent) citation from the Herman/Hamilton, 

### etal., group on the Lake St. George enclosure studies from 1982/1983. It focuses primarily on water quality measures, with some examinationof14C 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 somewhatreasonable sample size for statistical analysis.

Some aspects ofthe methodology were not fully explained within the article. The manufacturer ofthe commercial atrazine productwas not mentioned. The landuse characteristics ofthe Lake St. George watershed, and the presence or absence of background levels ofatrazine 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 oflateral water exchange within a reasonably tall (4.5 m) watercolumn that is notrealistic in a natural lake setting.

Description ofUse 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 ofatrazine (35 days apart) at 100 IlgiL.

Limitations ofStudy: With the exception ofthe primary production ('4C) endpoint, all otherreported 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 ofonly one atrazine treatment, insufficient description ofpotential background contamination in the control enclosures, and confounding effects associated with the lack oflateral water exchange and periphyton colonization due to the sheltered surfaces ofthe enclosure walls.

13Primary Reviewer: SaraHendrix, M.S., StaffScientist, Cambridge Environmental Inc

Secondary Reviewer: Anita Pease, M.S., SeniorBiologist, Environmental Fate and Effects Division, U.S. Environmental Protection Agency. 

# M,>t-**(..(t~(U**

14