UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

OFFICE OF 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

PC Code: 035201 

DP Barcode: 427440 

DATE: August I 3, 

20 15 

MEMORANDUM 

SUBJECT: 

FROM: 

THRU: 

TO: 

OVERVIEW 

Dicrotophos: Revised Drinking Water Assessment for Registration Review 

Andrew Shelby, Physical Sc entist ~ ~ -13- isEnvironmental Risk Branch 6 

Environmental Fate and Effects Divison (7507P) 

Mark Corbin, Branch Chief . ,/A() U '15-\3·\:S 

Will.iam P. Eckel.Ph.D, Senior Science Adviso~ //~ _ ._ £)C> / ()rg /

13 /;( 

Environmenta

Environmenta

l 

l 

Risk 

Fate and 

Branch 

Effects 

6 

Divison (7507P) 

./ W~~(), ~ 

Thurston Morton, Risk Assessor 

Charles Smith, Branch Chief 

Risk Assessment Branch 4 

Health Effects Division (7509P) 

Khue Nguyen, Chemical Review Manager 

Neil Anderson, Branch Chief 

Risk Management and Implementation Branch 1 

Pesticide Re-Evaluation Division (7508P) 

The Environmental Fate and Effects Division (EFED) has completed a Revised Drinking Water 

Assessment for the registration review of dicrotophos. This updates the July 14, 20 14 document 

(DP 398772) to respond to and incorporate, as appropriate, public comments from the 

dicrotophos registrant. 

Dicrotophos is registered for use on cotton and ornamental trees. For cotton, the maximum 

single application rate for the broadcast use is 0.5 pounds of active ingredient per acre (lb a.i./ A), 
2

and the maximum seasonal application rate is 1.2 lbs a.i./A; for ornamental tree application,

which is administered through tree injection, the calculated maximum single application rate is

0.228 lb a.i./A. There is no seasonal maximum application for the tree injection use. This 

drinking water assessment uses maximum rates and considers typical rates, although 

concentrations reported in the monitoring data exceed the modeled estimated drinking water 

concentrations (EDWC) when typical application rates are used. 

A single study is used estimate the aerobic soil metabolism input parameter, therefore the halflife was multiplied by three to conservatively derive the parameter. This input parameter is 

intended to represent the many varieties of soil and microbial communities that may metabolize 

dicrotophos at differing rates. Additional aerobic soil metabolism data (EFED typically requests 

this data for three or more soil types), would allow for better characterization of degradation 

behavior and reduce uncertainty in the modeled results.

This revised assessment changes the cotton percent cropped area (PCA) from 33% to 21% based 

on updated guidance (EPA, 2014a), incorporates application rate and application date 

recommendations made by the Biological and Economic Analysis Division (EPA, 2014b) and 

addresses comments on the original assessment made by Stone Environmental on behalf of the 

registrant, AMVAC (MRID 49582601). Registrant comments are addressed in more detail in 

Appendix A.

SWCC (Surface Water Concentration Calculator v1.106) modeling runs producing the highest 

EDWCs are presented in Appendix B. Based on modeling results from the Texas Cotton 

scenario, the maximum estimated surface water exposure concentrations for dicrotophos and 

assuming maximum application rates for current uses are:

8.75 μg/L for the 1 in 10 year annual peak concentration 

0.507 μg/L for the 1-in-10 year annual average, and 

0.306 μg/L for the 30 year annual average 

Based on ground water modeling results (PRZM-GW), the maximum estimated groundwater 

exposure concentration from six vulnerable scenarios for dicrotophos is 0.0003 μg/L for acute 

and chronic exposure based on post breakthrough average. Since the predicted concentrations in 

ground water are well below those calculated for surface water, surface water exposures are the 

driver for dicrotophos drinking water exposure.

Fate and Transport Characterization

The most significant degradation pathway for dicrotophos is aerobic soil metabolism (half-life = 

3 days; MRID 160826). Dicrotophos is more persistent to hydrolysis with a half-life of 72 days 

(MRIDs 160823). Dicrotophos hydrolyzes in pH 7 water with a half-life of 72 days (MRID 

160824). Dicrotophos is mobile with adsorption coefficients (Kd) ranging from of 0.1 to 3.58 

mL/g (FAO Classification; MRID 160828). A full summary of adsorption/desorption data can 

be found in the Dicrotophos RED (EPA 2006). It is not appropriate to use KOC to characterize 

the mobility of dicrotophos because adsorption coefficients do not sufficiently correlate with soil 

organic carbon content. Use of Kd rather than KOC is consistent with previous assessments. 
3

However, adsorption strongly correlates with clay content (r2 = 0.92).

Monitoring Data

Surface water monitoring data from the USGS National Water-Quality Assessment Program 

(NAWQA) and USDA’s Pesticide Data Program for dicrotophos indicate 57 detections in seven

states (Colorado, Georgia, Louisiana, Minnesota, Mississippi, North Carolina, and Texas) from 

approximately 8,500 samples. The peak detection of 6.83 parts per billion occurred in a cotton 

growing area of Washington County, Mississippi in 2005. All other detections were for 

concentrations less than 0.3 parts per billion. No NAWQA surface water monitoring has 

occurred in northwest Texas, one of the largest concentrated cotton growing areas in the United 

States. 

No groundwater monitoring data for dicrotophos was found.

Drinking Water Exposure Modeling

The modeling of the surface water and groundwater concentrations for the cotton use pattern 

follows standard modeling practices outlined in EFED’s Input Parameter Guidance (EPA 2009)

and is consistent with previous assessments. 

Surface water exposure for the tree injection use pattern is not quantitatively modeled as is 

discussed further in the paragraph below. The tree injection use is not expected to be 

concentrated to the extent that it will affect surface water intakes for drinking water. In a letter 

dated June 18, 2012, the registrant characterizes the Great Lakes region, an area of more than 

386,000 mi2

, to have the highest use of the dicrotophos tree injection with an estimated 3,600 to 

7,200 trees being treated over that area with 700 to 800 pounds of active ingredient. Nationally, 

2,500 to 2,600 pounds of active ingredient are used for tree injection on an annual basis. This 

compares to 900,000 pounds of active ingredient used nationally for cotton on an annual basis. 

The percent cropped area (PCA) for the cotton use pattern has been well characterized and 

estimated to be a maximum of 21% of any watershed upstream from a drinking water intake 

(EPA, 2014a). A similar calculation has not been made for a tree injection use pattern, but based

on the referenced information submitted by the registrant, the proportion of a given watershed 

treated for the tree injection use is not expected to approach the proportion determined for cotton. 

For this reason, the tree injection use pattern is not modeled for surface water exposure. 

The tree injection use is considered for groundwater, however, because exposure is not 

dependent on PCA adjustment factors. Dicrotophos tree injection use is labeled for 16 varieties 

of tree and 25 insect pests. Though modeling tree injection uses is not unprecedented, this use 

does not follow the typical modeling paradigm and therefore, conservative assumptions must be 

made to derive EDWCs. The method used to assess tree injection of dicrotophos has been used 

previously in EFED risk assessments in an assessment on emamectin (D351736). Aquatic 

exposures could occur from the chemical entering soil environments and subsequently entering 

aquatic environments. This could occur if the chemical is translocated primarily to the leaves, 

and the leaves fall to the soil and decompose. It is conservatively assumed that the total mass of 

the chemical applied to a tree via injection is applied directly to soil. For dicrotophos the amount 
4

of formulation injected is dependent on the tree size. A 72 inch diameter breast height (DBH) 

tree is conservatively assumed. Per label instructions, this number is divided by two to 

determine number of capsules to be injected. Tree injection capsules are small, disposable 

containers filled with formulated product delivered through a small tube via a hole drilled into 

the active xylem of the affected tree. Capsules range in size from one to three mL though the 

three mL capsule will be conservatively assumed for modeling. Assuming one tree per acre is 

treated, the application rate is:

72 in.DBH

1

×

1 capsule

2 in.DBH

×

3 mL

1 capsule ×

1 gallon

3785 mL

×

8 lbs a. i.

1 gallon = 0.228 lbs a. i./AA

This resulting application rate is less than half the maximum single application rate for the cotton 

use pattern and is also representative of many smaller trees on a given acre (e.g., six trees of 12 

inch DBH). Given this and the previous discussion regarding surface water exposure, EDWCs 

generated for the cotton use pattern are protective for the tree injection use pattern for 

both surface water and groundwater exposures.

Parameters for the derivation of Tier II surface water concentrations and the Tier I groundwater 

concentration for cotton are as follows:

Table 1. SWCC and PRZM-GW input parameter values for dicrotophos modeled for use 

on cotton (which is protective of the tree injection use)

PARAMETER (units) VALUE(S) SOURCE COMMENT

Application Rate (lb a.i./A)) See Table 2 Maximum Rates

Emergence to pre-bloom = 0.2 lb

a.i./A

1st bloom to 30 days pre-harvest = 

0.5 lb a.i./A with two applications

allowed

Number of Applications 3

Interval between Applications 

(days)

14 Labeled interval for cotton. 

Assumed interval for tree injection

based on label language: “Do not 

inject trees within two weeks of any 

other spray or soil chemical 

treatment” (Reg. No. 7946-11)

Molecular weight (g/mol) 237.19

Henry’s Law Constant (atmm3

/mol)

3.13 x 10-11 Dicrotopho

s RED

Vapor Pressure (torr) 7 x 10-5 43500401
5

PARAMETER (units) VALUE(S) SOURCE COMMENT

Solubility in Water @ 20 OC, 

(mg/L or ppm)

11,990 43603202, 

43603201

Soil Partition Coefficient (mL/g) Kd = 1.24 160828 Lowest non-sand Kd is used because 

adsorption does not correlate with 

organic carbon 

CAM (Chemical Application 

Method)

2 Cotton: foliar spray; emergence to 30 

days pre-harvest, unincorporated

Depth of Incorporation (inches) 0 –

Application efficiency (decimal) 0.95 Aerial application with no buffer to 

surface waters permitted on label

Spray drift fraction (decimal) 0.16

Percent Cropped Area (decimal) 0.21 PCA 

Guidance

Though the use pattern includes tree 

injections, the cotton only PCA 

adjustment factor is used because 

cotton and tree injection uses are 

spatially and temporally segregated.1

Application date (day/month) Variable (see Table 

2)

Application dates informed by 

BEAD

Hydrolysis Half-life (days) 72 160823

Aqueous Photolysis Half-life @ 

pH 7 (days)

Stable 160824

Aerobic Aquatic Metabolism 

Half-life (days)

16.2 2X aerobic soil metabolism 

parameter per Input Parameter 

Guidance1

Anaerobic Aquatic Metabolism 

Half-life (days)

48 160827 Anaerobic soil metabolism half-life = 

8 days. 3X half-life due to single 

half-life value and 2X for estimating 

an aquatic half-life with a soil halflife per Input Parameter Guidance1

.

Aerobic Soil Metabolism Halflife (days)8.1 160826 Because only one half-life is 

available, 3X is used per Input 

Parameter Guidance1

1 Development of Community Water System Drinking Water Intake Percent Cropped Area Adjustment Factors for 

use in Drinking Water Exposure Assessments: 2014 Update. September 9, 2014. 2 “Input Parameter Guidance” refers to Guidance for Selecting Input Parameters in Modeling the Environmental Fate 

and Transport of Pesticides; Version 2.1, October 22, 2009. 

Tier II surface water EDWCs were generated for uses on cotton with Mississippi, North 
6

Carolina, and Texas Cotton SWCC scenarios. Both BEAD recommended application dates

(Typical Rate – BEAD dates) and dates with minimum retreatment intervals (Typical Rate – 14 

day interval) were used along with maximum rates and minimum retreatment intervals. 

Application dates and typical rates were supplied by BEAD in a memo detailing application rates 

for many organophosphates (EPA, 2014).

Table 2. Parameterization of application rates and application dates for SWCC modeling

SWCC 

Scenario

Application rate 

and timing

Application 

rates (lb a.i./A)

Application date 

(1st application)

Application date 

(2nd application)

Application date 

(3rd application)

Mississippi 

Cotton

Maximum Rate 1st 0.2; 2nd 0.5; 

3rd 0.5

27 June 11 July 25 July

Typical Rate -

BEAD dates

0.28 27 June 27 July --

Typical Rate - 14 

day interval

0.28 27 June 11 July --

North 

Carolina 

Cotton

Maximum Rate 1st 0.2; 2nd 0.5; 

3rd 0.5

29 June 13 July 27 July

Typical Rate 0.22 29 June -- --

Texas 

Cotton

Maximum Rate 1st 0.2; 2nd 0.5; 

3rd 0.5

27 June 11 July 25 July

Typical Rate -

BEAD dates

0.24 27 June 27 July --

Typical Rate - 14 

day interval

0.24 27 June 11 July --

Table 3. Ranges of Tier II Estimated Drinking Water Concentrations (EDWCs) for surface 

water based on application of dicrotophos to cotton (protective of the tree injection use)

SWCC 

Scenario

Application rate 

and timing

1-in-10-year 

peak (ppb)

1-in-10-year 21 

day average 

(ppb)

1-in-10-year 

annual average 

(ppb)

Simulation 

average 

(ppb)

Mississippi 

Cotton

Maximum Rate 6.09 4.01 0.381 0.199

Typical Rate -

BEAD dates

3.21 1.67 0.193 0.0860

Typical Rate - 14 

day interval

4.49 2.45 0.204 0.0834

North 

Carolina 

Cotton

Maximum Rate 7.73 4.94 0.507 0.306

Typical Rate 1.62 1.05 0.0901 0.0503

Texas 

Cotton

Maximum Rate 8.75 4.63 0.430 0.222

Typical Rate -

BEAD dates

3.66 2.12 0.238 0.0934

Typical Rate - 14 

day interval

3.69 2.09 0.217 0.0839

The modeling of typical rates is performed for characterization and may be considered for 

quantitative purposes with the caveat that the values are not conservative in all cases. For 

instance, the typical rate 1-in-10-year peak EDWC for cotton in Mississippi is 3.21 to 4.49 ppb. 
7

However, monitoring data indicate that concentrations of 6.83 ppb occurred in Mississippi in 

2005 when dicrotophos had the same use pattern and maximum application rates as modeled in 

this assessment. Though the next highest detection was less than 0.3 ppb, one detection is 

indicative that similar concentrations could occur in other surface waters or at the same site at a 

different time but are not recorded. This monitoring data is derived from a targeted effort on the 

Bogue Phalia, a cotton predominant watershed, in which water samples were collected and 

dicrotophos concentrations were determined approximately every 14 days. Because pesticide

concentrations vary depending on weather, application patterns and subsequent dissipation, the 

likelihood of capturing the peak concentration of dicrotophos diminishes with a sampling 

interval of 14 days.

All presented modeled applications reflect aerial applications though dicrotophos may also be 

applied through ground applications. Ground applications reduces off-site spray drift but 

application efficiency is increased thereby increasing pesticide residues in run off. Modeling 

ground applications as opposed to aerial applications reduces peak 1-in-10-year EDWCs by 2% 

to 5%.

Based on an analysis of a more complete monitoring dataset for atrazine, the average bias factor 

on a sampling interval of 14 days for estimating a 60-day rolling mean was approximately 4 with 

a 95% confidence interval of approximately 7 (SAP, 2012). Due to differences in exposure 

window and the variability in field conditions, these bias factors cannot be directly applied to 

dicrotophos monitoring data. However, the bias factors illustrate the uncertainty associated with 

identifying 6.83 ppb as the highest concentration occurring in dicrotophos use areas. Given these 

uncertainties, EDWCs derived from typical rates model simulations should be used with caution 

and the awareness that it does not conservatively represent dicrotophos concentrations in all 

documented instances.

Tier I groundwater EDWCs were generated for the cotton use using PRZM-GW. In the case of a 

Tier I assessment, the cotton use is protective of the tree injection use since the application rate is 

highest. For Tier 1 PRZM-GW, all six standard scenarios were run as the scenarios represent a 

range of vulnerable ground water conditions that may occur across the United States, and 

dicrotophos is registered for national use. The highest groundwater concentration for acute and 

chronic EDWCs is 0.0003 ppb generated from the Florida Citrus scenario in PRZM-GW. This 

concentration is 1,600 times lower than the 30-year annual average EDWC for surface water. 
8

References

EPA. 2006. Interim Reregistration Eligibility Decision for Dicrotophos Case No. 0145. Office

of Pesticide Programs. Special Review and Registration Division. July 31, 2006

EPA. 2009. Guidance for Selecting Input Parameters in Modeling the Environmental Fate and

Transport of Pesticides. Environmental Fate and Effects Division. Office of Pesticide

Programs.

EPA. 2014a. Development of Community Water System Drinking Water Intake Percent Cropped

Area Adjustment Factors for use in Drinking Water Exposure Assessments: 2014 Update. 

Environmental Fate and Effects Division. Office of Pesticide Programs. September 9,

2014

EPA, 2014b. Information to support registration review of dicrotophos: cotton crop phenology in

the southern U.S., recent dicrotophos use patterns, and potential alternative insecticides

Biological and Economic Analysis Division. Office of Pesticide Programs. 2014

SAP. 2012. FIFRA SAP Meeting Held June 12-14, 2012 on Scientific Issues Associated with

for the Problem Formulation for the Reassessment of Ecological Effects from the Use of

Atrazine
9

APPENDIX A – Stone Environmental Comments Considered and Justification for not 

incorporating

The July 14, 2014 dicrotophos drinking water assessment (DP 398772) was posted in the public 

docket at regulations.gov (EPA-HQ-OPP-2008-0440-0023) for a 60-day public comment period. 

AMVAC Chemical Corporation, the dicrotophos registrant, submitted public comments to the 

docket on December 1, 2014 (EPA-HQ-OPP-2008-0440-0030), including comments related to 

drinking water. Subsequently on March 2, 2015 AMVAC submitted its own drinking water 

assessment for dicrotophos, conducted by Stone Environmental (MRIDs 49582600 – 01).

This revised drinking water assessment for dicrotophos incorporates some of the comments from 

MRID 49582601. The following parameters are updated or corrected: 

1) In SWCC modeling, foliar application is specified instead of ground application. 

Ground application was parameterized in error in the original drinking water assessment,

and is now corrected.

2) The cotton PCA is updated from 33% (as specified in 2012 guidance) to 21% (as 

specified in 2014 guidance). The original drinking water assessment was finalized prior 

to the release of the updated guidance. Because the drinking water assessment is being 

revised in 2015, the updated PCA is incorporated. 

The following comments from AMVAC/Stone were considered but not incorporated in updated 

SWCC modeling and EDWCs for the following reasons: 

1) Aerial buffers of 150 feet and ground buffers of 25 feet to surface waters are not 

included in EDWC calculations because they are not required on all dicrotophos end-use 

labels. EFED assesses risk based on the least restrictive label based on the assumption 

that an applicator, when given the choice, will acquire the product with the least 

restrictions associated with it. However, if the registrant chose to require these buffers on 

all current dicrotophos product labels, 1-in-10-year 21 -ay average EDWCs could be 

expected to be reduced by 5% to 6%.

2) The foliar half-life parameter in SWCC is maintained as “stable” even though 

AMVAC/Stone provided a rationale for a foliar half-life of 3 days based field studies in 

cotton. However, the studies cited by AMVAC/Stone only address dissipation of 

residues and do not specifically address degradation. The foliar half-life parameter only 

represents degradation that occurs on the leaf surface. Dissipation processes, such as 

foliar wash-off during precipitation events, are included in SWCC and are distinct from 

the foliar half-life. Therefore, foliar half-life estimates based on field dissipation study 

results would overestimate the amount of dissipation occurring and cannot be used for 

SWCC parameterization. 

3) Dicrotophos is registered for use on cotton across the United States without geographic 

restrictions on the end-use product labels. Although the North Carolina cotton scenario is 

representative of a region with a cotton only PCA of 8%, the national 21% PCA is 
10

applied because the North Carolina, Texas, and Mississippi cotton scenarios are 

considered together to represent drinking water concentrations nationally. Additionally, 

use of dicrotophos for tree injections is not considered in this approach. Although tree 

injection usage is believed to be small, use of the highest cotton PCA of 21% is 

conservative in this regard while the Delta and North Carolina cotton PCAs are not (20% 

and 8%, respectively).

4) BEAD estimates of application dates, based on USDA, National Cotton Council, and 

proprietary data, are used in this assessment in favor of those provided by AMVAC/Stone 

because the date selections are supported by a variety of accepted sources.
11

APPENDIX B - SWCC output file producing highest 1-in-10-year 21 day average EDWC

Variable Volume Water Model, SWCC Compatible Version

*******************************************

Performed on: 7/ 6/2015 at 16:45

Peak 1-in-10.0 = 8.75 ppb

Chronic 1-in-10.0 = 0.430 ppb

Simulation Avg = 0.222 ppb

4-d avg 1-in-10.0 = 7.52 ppb

21-d avg 1-in-10.0 = 4.63 ppb

60-d avg 1-in-10.0 = 2.19 ppb

90-d avg 1-in-10.0 = 1.58 ppb

Benthic Pore Water Peak 1-in-10.0 = 2.09 ppb

Benthic Pore Water 21-d avg 1-in-10.0 = 2.00 ppb

Benthic Conversion Factor = 1.61 -Pore water (ug/L) to (total mass, ug)/(dry sed 

mass,kg)

Benthic Mass Fraction in Pore Water = 0.230 

YEAR Peak 4-day 21-day 60-day 90-day Yearly Avg Benthic Pk Benthic 21-day

 1 4.92E+00 4.34E+00 3.25E+00 1.73E+00 1.59E+00 4.33E-01 1.59E+00 1.54E+00

 2 1.74E+01 1.49E+01 8.55E+00 3.84E+00 2.70E+00 7.36E-01 4.02E+00 3.82E+00

 3 8.31E-01 7.20E-01 5.02E-01 3.16E-01 2.68E-01 8.01E-02 2.25E-01 2.82E-01

 4 8.27E-01 7.17E-01 4.99E-01 3.64E-01 2.90E-01 7.88E-02 1.94E-01 1.81E-01

 5 1.25E+00 1.08E+00 6.45E-01 4.91E-01 3.69E-01 9.60E-02 3.32E-01 3.16E-01

 6 7.74E+00 6.70E+00 4.58E+00 2.19E+00 1.57E+00 4.01E-01 1.98E+00 1.87E+00

 7 2.43E+00 2.16E+00 1.42E+00 7.92E-01 6.46E-01 1.74E-01 6.73E-01 6.50E-01

 8 2.17E+00 1.92E+00 1.42E+00 8.24E-01 7.99E-01 2.18E-01 6.36E-01 6.10E-01

 9 8.86E+00 7.61E+00 4.64E+00 2.15E+00 1.57E+00 4.08E-01 2.10E+00 2.01E+00

10 1.01E+00 8.73E-01 5.29E-01 3.87E-01 3.45E-01 9.73E-02 2.76E-01 2.64E-01

11 3.11E+00 2.76E+00 1.87E+00 1.05E+00 7.53E-01 1.91E-01 7.42E-01 7.12E-01

12 1.35E+00 1.18E+00 8.89E-01 5.14E-01 3.78E-01 9.51E-02 3.26E-01 3.11E-01

13 1.38E+00 1.21E+00 9.19E-01 5.37E-01 4.33E-01 1.38E-01 3.36E-01 3.24E-01

14 4.12E+00 3.61E+00 2.48E+00 1.28E+00 9.35E-01 2.43E-01 1.03E+00 9.83E-01

15 3.52E+00 3.11E+00 2.10E+00 1.21E+00 9.36E-01 2.40E-01 1.21E+00 1.16E+00

16 1.95E+00 1.72E+00 1.35E+00 8.86E-01 8.14E-01 2.23E-01 6.62E-01 6.26E-01

17 3.04E+00 2.64E+00 1.86E+00 8.85E-01 6.70E-01 2.06E-01 8.37E-01 8.02E-01

18 4.37E+00 3.78E+00 2.22E+00 1.12E+00 8.08E-01 2.08E-01 9.84E-01 9.38E-01

19 1.42E+01 1.25E+01 8.88E+00 4.50E+00 3.14E+00 7.90E-01 4.19E+00 3.99E+00

20 7.94E-01 6.77E-01 4.67E-01 3.25E-01 2.91E-01 8.17E-02 1.80E-01 1.69E-01

21 2.41E+00 2.09E+00 1.25E+00 6.77E-01 7.16E-01 2.00E-01 6.65E-01 6.34E-01

22 8.24E-01 7.12E-01 4.96E-01 2.98E-01 2.29E-01 6.07E-02 1.43E-01 1.35E-01

23 2.17E+00 1.90E+00 1.43E+00 9.42E-01 6.74E-01 1.71E-01 6.68E-01 6.12E-01

24 8.54E-01 7.38E-01 4.98E-01 3.07E-01 2.40E-01 6.49E-02 1.50E-01 1.43E-01
12

25 1.47E+00 1.27E+00 7.92E-01 4.03E-01 4.28E-01 1.35E-01 3.66E-01 3.54E-01

26 2.32E+00 2.03E+00 1.25E+00 6.07E-01 5.51E-01 1.57E-01 5.20E-01 5.00E-01

27 4.70E+00 4.10E+00 2.54E+00 1.22E+00 1.14E+00 3.30E-01 1.19E+00 1.14E+00

28 9.44E-01 8.22E-01 6.52E-01 4.43E-01 3.28E-01 8.46E-02 2.63E-01 2.41E-01

29 2.15E+00 1.88E+00 1.12E+00 6.14E-01 5.04E-01 1.35E-01 5.71E-01 5.42E-01

30 3.37E+00 2.91E+00 1.95E+00 9.55E-01 6.78E-01 1.74E-01 1.09E+00 1.04E+00

******************************************************************************

**********************

Effective compartment halflives averaged over simulation duration:

washout halflife (days) = 104.602571075456 

water col metab halflife (days) = 20.8950713136149 

hydrolysis halflife (days) = 72.0050250173948 

zero photolysis 0

zero volatility 0

total water col halflife (days) = 14.0240475830529 

zero burial 0

benthic metab halflife (days) = 61.9113224107107 

benthic hydrolysis halflife (days) = 313.064356843458 

total benthic halflife (days) = 51.6892945440851 

***********************************************************************

Fractional Contribution of Transport Processes to Waterbody & Total Mass (kg):

Due to Runoff = 0.7371 17.63 

Due to Erosion = 0.0112 0.2689 

Due to Drift = 0.2516 6.018 

***********************************************************************

Flow in/out Characteristics of Waterbody:

Average Daily Runoff Into Waterbody (m3/s) = 1.105353439886830E-002

Baseflow Into Waterbody (m3/s) = 0.000000000000000E+000

Average Daily Flow Out of Waterbody (m3/s) = 1.105353439886858E-002

***********************************************************************

Inputs:

 31.00 = oc partitioning coefficient

 16.20 = water column half Life

 25.00 = reference temp for water column degradation

 48.00 = benthic Half Life

 25.00 = Reference temp for benthic degradation

 2.000 = Q ten value

 0.000 = photolysis half life

 40.00 = reference latitude for photolysis study

 72.00 = hydrolysis half life

 237.2 = molecular wt

 0.7000E-04 = vapor pressure

 0.1199E+05 = solubility
13

 0.1728E+07 = field area

 0.5260E+05 = water body area

 2.740 = initial depth

 2.740 = maximum depth

 3 1=vvwm, 2=usepa pond, 3 = usepa reservoir, 4 = const vol no flow, 5 = const vol 

w/flow 

F T = burial, else no burial

 0.1000E-07 = mass transfer coefficient 

 0.5000 = PRBEN

 0.5000E-01 = benthic compartment depth

 0.5000 = benthic porosity

 1.350 = benthic bulk density

 0.4000E-01 = OC frcation in benthic sediment

 5.000 = DOC in benthic compartment

 0.6000E-02 = benthic biomass

 1.190 = DFAC

 30.00 = SS

 0.5000E-02 = chlorophyll

 0.4000E-01 = OC frcation in water column SS

 5.000 = DOC in water column

 0.4000 = biomass in water column

FRACTION AREA CROPPED = 0.210000000000000