an application of dazomet. In total, 452 pounds (205 kg) BasamidG ® were applied by granular spreader to a fallow, 1.0175 acre (0.4118 ha) plot at Plant Sciences, Inc., Nakano Complex, Watsonville, California. Application began October 18, 2006 at 08:45. It took 2 hours 15 minutes to complete, and a sprinkler system was activated approximately 30 minutes after the application finished to incorporate the pesticide into the soil. This first irrigation session lasted 3 hours 15 minutes; intermittent watering continued over the next few days. Air monitoring with 8 receptors (numbered 1 through 8) began 12 hours before application for a background sample and continued for 6 consecutive days and a total of 16 sampling periods. Air monitoring for period 1 began at about 8:45, coincident with the application. Data for the 17th and 18th sampling periods were collected 5 days after the 16th period. Parakrama (Gura) Gurusinghe will report on this study and its results in greater detail. Tammy Roush conducted modeling and back-calculation of the flux rates following methods established by Johnson et al. (1999). The Industrial Source Complex Short Term (ISCST3) (U.S. EPA 1995) was used to model the application. Pam Wofford and Tammy used WEATH6 to convert data recorded by the Department of Pesticide Regulation’s (DPR’s) weather statio

Arnold Schwarzenegger

Pam Wofford

CiteSeerX

Department of Pesticide Regulation

Mary-Ann Warmerdam  M E M O R A N D U M 	 Arnold Schwarzenegger 
Director	 Governor 
Name:	 Pam Wofford

 Senior  Environmental  Scientist, Supervisor 

Environmental Monitoring Branch 

Original signed by Bruce Johnson for 
FROM: 	 Tamara Roush, Ph.D. 

Environmental Research Scientist 

Environmental Monitoring Branch 

(916)  324-4279 
DATE:	 June 20, 2007 
SUBJECT: FLUX ESTIMATION AND EMISSION OF METHYL ISOTHIOCYANATE 

RESULTING FROM A SMALL PLOT APPLICATION OF DAZOMET IN 

WATSONVILLE, CALIFORNIA

In October 2006, the Department of Pesticide Regulation conducted a small plot study in 
conjunction with Plant Sciences, Inc. to monitor methyl isothiocyanate (MITC) emissions from 
an application of dazomet. In total, 452 pounds (205 kg) BasamidG
® were applied by granular 
spreader to a fallow, 1.0175 acre (0.4118 ha) plot at Plant Sciences, Inc., Nakano Complex, 
Watsonville, California. Application began October 18, 2006 at 08:45. It took 2 hours 15 minutes 
to complete, and a sprinkler system was activated approximately 30 minutes after the application 
finished to incorporate the pesticide into the soil. This first irrigation session lasted 3 hours  
15 minutes; intermittent watering continued over the next few days. Air monitoring with  
8 receptors (numbered 1 through 8) began 12 hours before application for a background sample 
and continued for 6 consecutive days and a total of 16 sampling periods. Air monitoring for 
period 1 began at about 8:45, coincident with the application. Data for the 17th and 18th 
sampling periods were collected 5 days after the 16th period. Parakrama (Gura) Gurusinghe will 
report on this study and its results in greater detail. 
Tammy Roush conducted modeling and back-calculation of the flux rates following methods 
established by Johnson et al. (1999). The Industrial Source Complex Short Term (ISCST3)  
(U.S. EPA 1995) was used to model the application. Pam Wofford and Tammy used WEATH6 
to convert data recorded by the Department of Pesticide Regulation’s (DPR’s) weather station 
into the format required by ISCST3. The wind direction was calculated from magnetic north, 
which matched the orientation of the test plot. The receptor coordinates were input into the 
control file in the following order: 7, 8, 1, 2, 3, 4, 5, and 6. Appendix A shows an example of the 
control file for sampling period 1 and its resulting output data.   
Modeled and measured MITC concentrations were compared by regression analysis for each 
period. Concentration data for all periods are listed in Appendix B. Only periods 6, 12, and 18 
had significant r
2 values at alpha = 0.05. Additionally, period 2 showed an unusually high 
measured concentration of 1058 μg MITC/m
3 at receptor 2. After consultation between Tammy, 
Pam, Gura, and Bruce Johnson, it was determined that this measurement corresponded to a small 
1001 I Street  •  P.O. Box 4015  •  Sacramento, California 95812-4015  •  www.cdpr.ca.gov 
A Department of the California Environmental Protection Agency 
Printed on recycled paper, 100% post-consumer--processed chlorine-free. Pam Wofford  
June 20, 2007 
Page 2 
spill of BasamidG
® at that receptor during application. Based on the recorded wind directions 
during this time period, this receptor was upwind from the plot.   
Therefore, the high concentrations would not have come from the plot. We decided to remove 
measured and modeled data for receptor two from all analyses and re-run the regressions. 
Although this improved the fit of the data for all periods, 6, 12, and 18 were still the only  
3 periods with significant r
2 values (Table 1). Consequently, measured and modeled 
concentrations for the 15 nonsignificant periods were sorted from lowest to highest and 
reanalyzed. After sorting, 14 of these 15 periods were significant at the 0.05 level; period 4  
had a p-value equal to 0.07 (Table 1). Additionally, the intercepts for periods 3, 4, 5, 7, 8, 9, 10, 
15, and 17 were significantly different from zero. We chose not to force them through the origin. 
Table 1. Comparisons of regression analyses before and after sorting data within each sampling 
period. Data from receptor two were excluded from all analyses. 
PERIOD Before  sorting 
R
2  Intercept (ug/m
3) 
After sorting 
R
2  Intercept (ug/m
3) 
Value  P  Value  P  Value  P  Value  P 
1  0.18  0.336 21.99 0.552  0.75 0.012  -5.55  0.784 
2 0.21  0.359  56.16  0.16 0.93  0.002  6.56  0.615 
3 0.38  0.142  181.19  0.086 0.72  0.016  148.31  0.049 
4 0.10  0.487  239.18  0.024 0.51  0.07  151.11  0.041 
5  0.26  0.24 92.39 0.009  0.89  0.001 73.04  0.0004 
6  0.80  0.007 30.53 0.108  not sorted; no change 
7 0.14  0.401  138.84  0.003 0.88  0.002  115.13  <0.0001 
8  0.41  0.119 97.97 0.009  0.77  0.01 88.97  0.002 
9  0.37  0.144 46.87 0.017  0.69  0.021 40.78  0.008 
10 0.49  0.08  6.61  0.651  0.62  0.036  4.17  0.741 
11  0.03  0.694 82.45 0.031 0.71  0.017  55.13  0.015 
12  0.60  0.04 10.25 0.152  not sorted; no change 
13  0.38  0.139 13.41 0.383  0.77  0.009  5.29  0.564 
14 0.35 0.162  1.96  0.835  0.50 0.06  -0.55  0.947 
15  0.04  0.602 42.99 0.098  0.76  0.011  9.08  0.011 
16 0.42 0.116  3.15  0.502  0.91  0.001  0.01  0.997 
17 0.08 0.547  4.92  0.032  0.84  0.004  3.05  0.007 
18 0.64  0.03  0.21  0.671  not sorted; no change Pam Wofford  
June 20, 2007 
Page 3 
Flux estimates from the regression analyses were used to calculate the percent emission of MITC 
for each period per the equation: 
% emission =[((flux μg / m
2 s* 1 g / 1 x 10
6 μg) x (total seconds ))/total MITC applied g/m
2] x 100 
where flux and total seconds are understood to be from the particular sampling period being 
estimated.  Amount of MITC applied was calculated from the total amount of BasamidG
® 
during the application as follows: Application rate of BasamidG
® = 452 lb (205 kg)/ 1.0175 
ac (0.4118 ha)= 444 lb/ac (498 kg/ha). The active ingredient, dazomet, comprises 99% of 
BasamidG
®, therefore application rate of dazomet = 447 lb (203 kg) / 1.0175 ac (0.4118 ha) 
=440 lb/ac (493 kg/ha). Total dazomet applied = 447 lb x (453.6 g/lb) x (1 mol/162.3 g)  
(i.e. molecular weight of dazomet) = 1,250 mol. Whereas Gamliel et al. (2004) estimated that 
98% of the dazomet in BasamidG
® breaks down into MITC after incorporation into the soil, 
DPR assumes 100% degradation of dazomet into MITC. Thus, total amount of MITC applied  
= 1,250 mol x (73.1 g/mol) (i.e. molecular weight of MITC) = 91,405 g. The plot area measured 
50.6m x 81.4m, or 4119 m
2, so the value used in the equation for percent emission for total 
MITC applied = 91,405g/4119m
2, or 22.2 g/m
2. 
The 24-hour time-weighted average (TWA) flux rates were also calculated according to the 
equation: TWA = Σ (sampling hours * flux estimate) / total hours. Table 2 lists the flux estimates 
for each period, 24-hour TWA flux rates, percent emission, and cumulative emission. By the  
end of sampling period 18, 32% (29,250g) of the MITC applied was emitted from the plot.  
Ten percent of the MITC applied, or 9,140g, was released during the first 24-hr period.  
Twelve percent, 10,969 g, was released during the second 24-hr period; period 6 alone accounted 
for 8%. Emission of MITC declined over the remainder of the monitoring. During period 16, 127 
hours after the application was completed, 1% MITC was emitted from the plot. The 24-hr  
time-weighted average flux during periods 17 and 18, which began 10 d, 8h after the application 
ended, was 0.75 μg/m
2s.  Essentially 0% MITC was emitted by this time. Pam Wofford  

June 20, 2007 

Page 4 

Table 2. MITC emissions calculated from flux estimates for each sampling period. Note that the 
flux estimate is 100x the multiplicative coefficient derived from the regression. 
hours in  Flux estimate  %  TWA flux  Cumulative % 
Period  period  (μg/m
2s)  emission  (μg/m
2s)  emission 
1 7  29  3  3 

2 4  35  2  5 

3 6  26  3  8 

4 6  21  2  27.0  10 

5 6  17  2  12 

6 6  79  8  20 

7 6  8  1  21 

8 6  8  1  28.0  22 

9 6  11  1  23 

10 6  15  1  24 

11 12  9  2 6.5  26 

12 12  14  3  29 

13 12  7  1  10.5  30 

14 12  7  1  31 

15 12  1  0 4.0  31 

16 12  3  1  32 

17 12  0.7  0  32 

18 12  0.8  0  0.75  32 
Pam Wofford  
June 20, 2007 
Page 5 
References: 
Gamliel, Abraham, Miriam Austerweil, Yehudith Riben, Bracha Steiner, Marina Beniches, 
Victor Zilberg, Shachaf Triki, Eyal Klein, Moran Siti. 2004. Application of dazomet (Basamid
®) 
as soil fumigant: generation, movement, and dissipation of MITC and pest controls. Available at: 
<www.agri.gov.il/AGEN/Reports/Gamli009.html>. 
Johnson, Bruce, Terrell Barry, and Pamela Wofford. 1999. Workbook for Gaussian modeling 
analysis of air concentration measurements. Report EH-99-03. California Department of 
Pesticide Regulation. 
U.S. EPA. 1995. User’s Guide for the Industrial Source Complex Dispersion Models, Volume 1. 
User Instructions. U.S. EPA Office of Air Quality Planning and Standards; Emissions, 
Monitoring, and Analysis Division, Research Triangle Park, North Carolina. Pam Wofford  
June 20, 2007 
Page 6 
Appendix A: Control file and the first page of output data from ISCST3 for sampling interval 1. 
CO STARTING 
CO TITLEONE BASAMID TEST 
CO TITLETWO PERIOD 1 
CO MODELOPT CONC RURAL 
CO AVERTIME PERIOD 
CO POLLUTID OTHER 
CO FLAGPOLE 1.20 
CO RUNORNOT RUN 
CO ERRORFIL D:\Gaussian\P1newERR.OUT 
CO FINISHED 
SO STARTING 
SO LOCATION SRC0001 AREA 0.0 0.0 0.0 
SO SRCPARAM SRC0001 1.e-4 0.00 50.0 81.4 
SO EMISUNIT 0.100000E+07 (GRAMS/M**2/SEC) (MICROGRAMS/METER**3) 
SO SRCGROUP ALL 
SO FINISHED 
RE STARTING 
RE DISCCART 62.2 -13.91 1.20  
RE DISCCART 24.4 -12.3 1.20  
RE DISCCART -13.1 -12.78 1.20 
RE DISCCART -12.2 40.5 1.20 
RE DISCCART -13.1 93.89 1.20 
RE DISCCART 25.3 93.0 1.20 
RE DISCCART 62.2 94.87 1.20 
RE DISCCART 62.2 40.5 1.20 
RE FINISHED 
**receptor 7 
**receptor 8 
**receptor 1 
**receptor 2 
**receptor 3 
**receptor 4 
**receptor 5 
**receptor 6 
ME STARTING 
ME INPUTFIL D:\Gaussian\WP1.MET (4I2,2F9.4,F6.1,I2,2F7.1) 
ME ANEMHGHT 10.0 METERS 
ME SURFDATA 99999 2006  
ME UAIRDATA 99999 2006  
ME WINDCATS 2.00 3.09 5.14 8.23 10.80 
ME FINISHED 
OU STARTING 
OU POSTFILE PERIOD ALL PLOT D:\Gaussian\P1.RAW 
OU FINISHED - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
Pam Wofford  
June 20, 2007 
Page 7 
* ISCST3 (02035): BASAMID TEST 
* MODELING OPTIONS USED: 
*  CONC  RURAL FLAT  FLGPOL 
*   POST/PLOT FILE OF PERIOD VALUES FOR SOURCE GROUP: ALL 
*   FOR A TOTAL OF  8 RECEPTORS. 
*   FORMAT: (3(1X,F13.5),1X,F8.2,2X,A6,2X,A8,2X,I8.8,2X,A8) 
*  X  Y  AVERAGE CONC   ZELEV  AVE  GRP   NUM HRS   NET ID 
*	 ___________  ___________   ___________  ______  ______  ________  ________  ________ 
62.20000   -13.91000    25.05398  0.00  PERIOD  ALL  00000007  NA 
24.40000   -12.30000     0.02400  0.00  PERIOD  ALL     00000007    NA
 -13.10000     -12.78000     0.00000  0.00  PERIOD  ALL     00000007    NA
 -12.20000    40.50000  101.03069  0.00  PERIOD  ALL  00000007  NA
 -13.10000    93.89000  241.50749  0.00  PERIOD  ALL  00000007  NA 
25.30000  93.00000  360.79279  0.00  PERIOD  ALL  00000007  NA

62.20000  94.87000  225.76189  0.00  PERIOD  ALL  00000007  NA

62.20000  40.50000  453.03238  0.00  PERIOD  ALL  00000007  NA

***   02/22/07 
 *** PERIOD 1   ***  10:44:22 
**MODELOPTs:     PAGE  6 
CONC     RURAL FLAT  FLGPOL 
*** THE FIRST   7 HOURS OF METEOROLOGICAL DATA *** 
 FILE:   D:\Gaussian\WP1.MET  
 FORMAT: (4I2,2F9.4,F6.1,I2,2F7.1)  
 SURFACE STATION NO.:  99999  UPPER AIR STATION NO.:  99999 
 NAME: UNKNOWN 	 NAME: UNKNOWN 
 YEAR:   2006 	 YEAR:  2006 
FLOW   SPEED  TEMP  STAB  MIXING HEIGHT (M)  USTAR  M-O LENGTH  Z-0 IPCODE PRATE 
YR MN DY HR VECTOR  (M/S)   (K)  CLASS   RURAL  URBAN    (M/S)     (M)   (M)  (mm/HR) 
06 10 18 08  102.9   1.19  281.7  4  300.0   300.0  0.0000    0.0  0.0000  0  0.00 
06 10 18 09  328.5   1.16  285.2  3  300.0   300.0  0.0000    0.0  0.0000  0  0.00 
06 10 18 10  339.6   1.15  289.3  2  300.0   300.0  0.0000    0.0  0.0000  0  0.00 
06 10 18 11  57.5  1.17  293.5  2  300.0  300.0  0.0000     0.0  0.0000  0  0.00 
06 10 18 12  41.7  1.42  295.6  1  300.0  300.0  0.0000     0.0  0.0000  0  0.00 
06 10 18 13  41.8  2.96  295.8  2  300.0  300.0  0.0000     0.0  0.0000  0  0.00 
06 10 18 14  64.9  3.76  295.6  3  300.0  300.0  0.0000     0.0  0.0000  0  0.00 Pam Wofford  
June 20, 2007 
Page 8 
Appendix B. Measured and modeled MITC concentrations for all 18 periods. 
Period Receptor  measured  modeled  Period Receptor  measured  modeled  Period Receptor  measured  modeled 
1 1  8.18744211  0 7 1  155.158045  0  13 1  77.19149836  415.64706
 2  .  101.03069  2  .  0  2  .  529.11945
 3  31.07759763  241.50749  3  92.9366525  0  3  11.75762055  149.76237
 4  29.90193606  360.79279  4  128.2958504  242.74641  4  14.41416894  21.55596
 5  179.1055841  225.76189  5  97.56773311  191.67982  5  9.894170784  2.10798
 6  76.40621138  453.03238  6  199.4023076  1471.31104  6  26.09232003  601.07111
 7  7.041995903  25.05398  7  151.1326439  1137.81787  7  26.43337744  620.86011
 8  12.25969813  0.024  8  224.9308132  109.18357  8  63.61780871  808.83838 
2 1  5.815352531  0 8 1  79.95066874  0  14 1  1.656074689  0
 2  52.78308595  186.59724  2  .  0  2  .  8.34322
 3  78.6072745  338.37653  3  62.62989067  0  3  4.597190297  49.79597
 4  94.01588869  405.66583  4  86.07463562  0  4  37.61416707  295.5051
 5  105.335334  172.11195  5  71.16299632  0  5  23.55421897  307.35385
 6  156.6968836  208.33745  6  166.4009496  1436.2334  6  21.57989633  357.77359
 7  .  0.00004  7  184.8208364  1222.19275  7  8.539364898  286.7222
 8  .  0  8  209.1917591  157.12614  8  4.791775571  312.61777 
3 1  304.1726107  0 9 1  30.58384317  0.0026  15 1  24.06345519  28.83606
 2  .  0  2  .  126.42984  2  .  141.80403
 3  54.44667895  0  3  67.88253394  136.38155  3  6.1584162  0
 4  55.09113298  0  4  78.79648396  438.55887  4  8.095140386  128.36073
 5  66.63885619  0  5  20.90713902  77.5302  5  5.907500972  284.53262
 6  451.3949033  1496.75183  6  90.28555237  545.60242  6  20.70209683  1399.64685
 7  382.3556338  1379.20374  7  72.28752688  268.21353  7  15.03932576  929.67804
 8  559.9385082  322.83984  8  86.95911863  36.09587  8  25.82946404  232.72194 
4 1  76.01112301  0 10  1  2.745325657  0.13137  16 1  1.793932576  62.47061
 2  .  0  2  .  80.14397  2  .  47.17303
 3  60.56447988  0  3  11.05492884  21.07357  3  14.00291152  59.3914
 4  417.9371815  0  4  21.54095946  366.61902  4  24.85406595  488.30502
 5  140.1123163  0  5  39.57516875  312.70602  5  8.370821865  100.50159
 6  50.42121796  1489.74109  6  99.77736971  331.05228  6  12.87993365  414.27103
 7  331.9312458  471.06015  7  5.10111576  3.96029  7  3.004996586  267.71478
 8  407.8094332  29.91035  8  7.817460588  0.01519  8  3.606120751  137.74352 
5 1  85.54929003  20.10756 11  1  92.36103773  0  17 1  8.532716776  203.73401
 2  .  348.00464  2  .  0  2  .  451.27933
 3  80.86082425  244.49057  3  41.72874009  0  3  3.069722624  100.83681
 4  152.7911026  348.21597  4  59.58699828  190.33392  4  4.34117585  84.85691
 5  63.8390456  77.34594  5  44.06238384  172.17326  5  3.128993447  112.69553
 6  162.0107502  641.72162  6  102.3229511  1191.92224  6  9.032442856  794.77002
 7  108.8722033  421.95157  7  97.3534387  1056.29114  7  3.670667694  935.10028
 8  153.6374483  38.71024  8  192.6614425  193.83476  8  8.3124396  394.27292 
6 1  5.03549612  28.28474 12  1  11.17821177  0.0532  18 1  0.342759212  73.12766
 2  .  1.05923  2  .  251.28008  2  .  368.19019
 3  44.67099972  0  3  9.722936327  141.92223  3  0.756000756  230.60695
 4  45.70651663  0.14836  4  18.72311715  130.46834  4  1.938845466  219.54231 Pam Wofford  
June 20, 2007 
Page 9 
5  98.79920961  14.27261  5  27.10183846  67.49207  5  2.577978742  215.2299
 6  213.3764229  227.71033  6  56.23840445  329.23486  6  2.958579882  279.42398
 7  13.80562802  1.01542  7  9.967734906  61.68396  7  0.269748041  0.48003 
8  7.327825645  0.00097  8  21.26825016  2.18349  8  0.646983976  12.26311 Water Tower 
Pam Wofford 
June 20, 2007 
Page 10 
N 
Fence 
18.1 
12.2 
18.5 12.3 18.3 
12.2 
18.1 
11.6 
Stn. 1 
Stn.2 
Stn. 3 
Stn. 4  Stn. 5 
Stn.
Stn. 7 Stn. 8 
38.4  37.5 
40.8 
40.5 
37.5 37.5 
40.5 
40.8 
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SUBJECT: FLUX ESTIMATION AND EMISSION OF METHYL ISOTHIOCYANATE RESULTING FROM A SMALL PLOT APPLICATION OF DAZOMET IN

http://www.cdpr.ca.gov/docs/emon/pubs/ehapreps/analysis_memos/1913mitc.pdf

SUBJECT: FLUX ESTIMATION AND EMISSION OF METHYL ISOTHIOCYANATE RESULTING FROM A SMALL PLOT APPLICATION OF DAZOMET IN

Abstract

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