Document 2qNOoyQqKpvjOpjd09358qk0g

m form 0747 & y I'f.-ir ;n.|uuivi [:!.. HNICAL REPORT SUMMARY Om 2/27/78 1/ TO: TECHNICAL COMMUNICATIONS CENTER - 201-2CN (Important - // report it printed on both tides o f paper, send two copit to TCC .I SEP 0 6 1S78 O ivition Protect Report Title ' EE 6 PC Fate of Fluorochemicals Adsorption of FC 95 and FC 143 on soil To AutnoruU D. L. Bacon Stephen K. Welsh <SfcU> Notebook Reference Dopi. N im b o . 0222 Prefect N w nbxr 9970612633 Report Number 73583 n STSTT Coreienei SECU RITY #40673, 47704 D Open (Company Confidentiel) E Doted (Special Authorization) 3M C H EM IC A L ^ REGISTRY ^ New Cham icalrm Eortad Yet Q No KEYW ORDS: (Select tarrm from 3M Thesaurus. Suggest other applicable terms.) CURRENT O BJECTIVE: To obtain an indication of FC 95 and FC 143 mobility in sandy loam soil. EE' 6 PC - Div. Fluorochemical Soil Adsorption Mobility R E P O R T A B S T R A C T : (200-2S0 words) This abstract information it distributed by the Technical Com m unications Cantar to alert 3M'ert to Company R&O. It is Company confidential material. As a part of the Fate of Fluorochemicals Project, an indication of mobility of FC 95 and FC 143 in sandy loam soil was desired. Adsorption-desorption experiments (after Davidson, 1976, and Hamaker, 1975) along with water solubility data can provide such information. The adsorption coeffients for FC 95 and FC 143 were determined to be 0.99 and 0.38, respectively. For FC 9S adsorption and desorption could be described by a single valued function while for FC 143, they could not. Based on these data, both compounds would be judged mobile in the sandy loam soil used in this study. 62 :6 HV 6 1inr hOOZ 03H i ddi Q333H EIDl08759 O r* o o oo C0004 CONCLUSIONS Adsorption coefficient for FC 95 and FC 143 were 0.99 and 0.38, respectively. For FC 95, adsorption and desorption could be described by a single valued function while for FC 143, they could not. Considering adsorption coefficients, desorption characteristics and water solubilities, both compounds would be judged mobile in the sandy loam soil used in this study. INTRODUCTION As a part of the Fate of Fluorochemicals Project, an indication of mobility of FC 95 and FC 143 in sandy loam soil was desired. Adsorption- ' desorption experiments (after Davidson, 1976, and Hamaker, 1975) along with water.solubility data can provide this indication of mobility. This approach is used by the U. S. EPA in pesticide registration requirements. MATERIALS AND METHODS GLKO0I019 Duplicate 5-g samples of air-dried Brill sandy loam soil (57% sand, 36% silt, 7% clay, 2.5% organic matter, 1.5% organic carbon, with pH 6.5 and C.E.C. of 15.3 meq./lOOg) were shaken with 25 ml of solution in 50 ml. poly propylene centrifuge tubes for 24 hours on a wrist action shaker at room temp. (16-19C). Polypropylene tubes were used because they were found in separate experiments (3M Tech Notebook #470673, C. H. Schrandt) to absorb less FC 95 and FC 143 than glass or polyethylene tubes. Solutions were made by diluting a stock solution of each chemical. Concentrations of 14C-labeled FC 95 were 282 mg/1., 158 mg/1., 90 mg/1., 51 mg/1., 28 mg/1., (100%, 56%, 32%, 18%, 10%, 1% of stock). Concentrations of 14C-la( .cd FC 143 were 523 mg/1., 293 mg/1., 167 mg/1., 94 mg/1., S2 mg/l., and 5.2 mg/1. EID108760 G0G005 After shaking the initial solutions as well as the three desorption extractions with deionized water, the samples *ere centrifuged at 5000 rpm for 10 min., and three aliquots of each supernatant solution were taken for scintillation counting. After the adsorption step, 22.5 ml of solution were recovered. Therefore, it was assumed that 2.5 ml of liquid remained with the soil in each step and this amount was accounted for in the desorption calculations (see Results and Discussion section). In the FC 95 experiment, the supernatant liquid was simply drained off at each step and the next 25 ml of liquid were put into the tubes. In the FC 143 experiment, the supernatant liquid remaining after the draining step was absorbed with a cotton swab before putting the next 25 ml of liquid into the tubes. ' The procedures for the FC 95 and FC 143 experiments were recorded in 3M Technical Notebook #40673, p. 49 and p. 51, respectively. From the raw counting data, disintegrations per minute (DPM) and FC 95 and FC 143 concentrations were calculated for all of the supernatant solutions. Statistical analysis and plotting of the data was done with the MINITAB package of the 3M TRAC coxqsuter service. RESULTS AND DISCUSSION EID108761 FC 95 Adsorption data for FC 95 are presented in TABLE I and FIGURE I. Comparing the regression equation of the adsorption isotherm (FIGURE 1) 1/N x/m -0.29 0.99C with the Freundlich equation x/m KC ' , it could be seen that the adsorption coefficient, K, equaled 0.99 and the exponent, N, equaled one. The linear shape of tho adsorption isotherms (Nl) indicated GLK001020 G.0G006 if r4 T n I;I that FC 95 adsorption on soil would be independent of concentration. The low adsorption coefficient (K=0.99) indicated that FC 95 would be mobile, i.e., it would move readily with the ground water through this sandy loaa soil. TABLE I A Initial FC 95 Cone., mg/1 282.2 158.0 90.0 51.0 282.. 8 FC 95 ADSORPTION DATA B Equil. Cone., C, mg/1. 233.9 134.2 76.9 42.0 22.1 2.0 C % Removed , nBy Soil *=? x 100 ) 17.1 15.1 14.6 17.8 21.1 27.0 GLK001021 D Total FC 95 In Initial Sol'n (A x 0.025 liters) 7.0500 3.9500 2.2500 1.2750 0.7000 0.0700 EF Total FC 95 in Sol'n at Equil., mg (B x 0.025 liters) 5.84750 3.35500 1.92250 1.05000 0.55250 0.05000 FC 95 Adsorbed on Soil, x/o, ug/g f(D-E) x 105 ug/ng -, 2_________5 g Soil 1 240.8 119.0 65.7 45.3 29.5 3.8 EID 108762 Desorption data for FC 95 are shown in TABLE II and FIGURE 2. For comparison. desorption isotherms for the pesticide fluometuron are given in FIGURE 5. For clarity FC 95 desorption isotherms are not drawn in FIGURE 2. However, all of the data points lie very close to the adsorption isotherms indicating that adsorption and desorption could be described by a single-value' function with desorption coefficients, K', equaling the adsorption coefficient 00007 240 Ml ' I H | 5 A Adsorbed on Soil, x/m, bg/g* GLK001022 FIGURE 1 FC 95 Adsorption Isotherm This, along with the observation that approximately all of the adsorbed FC 95 was subsequently desorbed (TABLE II, Column H) indicated that binding forces were weak and would be another indication of high mobility of FC 95. Material balance data for FC 95 are presented in TABLE III and these data indicate that all of the chemical was accounted for throughout the experiment. EID108763 G00008 6 A Equil. Cone, in Solution, C, mg/1. 233.900 134.200 76.900 42.000 22.100 2.000 TABLE II FC 95 DESORPTION ISOTHERM DATA* B Equil. Cone, in First Desorption . mg/1. C Equil. Cone, in Second Desorption mg/1. 52.7000 30.3000 18.3000 9.6000 5.3000 0.6000 14.9000 9.0000 5.3000 2.9000 1.7000 0.2000 EID108764 D Equil. Cone, in Third Desorption mg/1. 5.20000 2.80000 1.80000 1.00000 0.60000 0.10000 E Amount Adsorbed on Soil, x/m ug/g (Column F, TABLE I) 240.800 119.000 65.700 45.300 29.500 3.800 F Amount on Soil After First Desorption, ug/g 67.6000 19.4500 3.3000 . 13.2000 11.4000 1.7000 G Amount on Soil After Second Desorption, ug/g 12.0000 -14.9000 -16.7000 . 2.0500 4.7000 0.9000 H Amount on Soil After Third Desorption, ug/g -9.1500 -25.8000 -23.9500 -2.0000 2.2500 0.4500 Columns F, G, and H were calculated in the same way as Column F, TABLE I with correction for the amount of FC 95 in the 2.S ml of solution remaining from the previous step in each case (See Materials and Methods Section.) GLK001023 FIGURE 2 FC 95 DESORPTION DATA POINTS AND ADSORPTION ISOTHERM FIGURE 3 ADSORPTION AND DESORPTION ISOTHERMS FOR FLUOMETURON ON COBB SAND. SOLID AND BROKEN LINES ARE BEST FIT FOR ADSORPTION AND DESORPTION, RESPECTIVELY. (From Davidson, et 1, 197S) G0Q009 " f;i,i 7 GLK001024 TABLE III FC 9S Material Balance* A Total Initial ' FC 95 in Solution, mg. (Column D, TABLE I) 7.05000 3.95000 2.25000 1.27500 0.7000 0.0700 B FC 95 in Solution at Equil., mg. (Column E, TABLE I) 5.84750 3.35500 1.99250 1.0500 0.55250 0.05000 C FC 95 on soil at Equil., mg. (A - B) 1.20250 0.S9500 0.32750 0.2250 0.14750 0.02000 D Amount Removed by First Desorption, mg. 0.864500 0.497750 0.311000 0.159000 0.090500 0.011500 G Total Amount Desorbed by Three Desorptions, mg (D+E+F) 1.2483 0.7240 0.4473 0.2350 0.1363 0.0178 E Amount Removed by Second Desorption, mg. 0.278000 0.1717S0 0.100000 0.055750 0.033500 0.004000 F Amount Removed by Third Desorption, mg. 0.105750 0.054500 0.036250 0.020250 0.012250 0.002250 ' H Amount Remaining on Soil After 3 Desorptions, mg. (C - G) I Amount Desorbed as Percent of Amount Adsorbed (G/C x 100) -0.45750 -0.12900 -0.11975 -0.01000 0.11250 0.002250 103.805 121.681 136.565 104.444 92.373 88.750 `Columns D, E, and F were obtained by first calculating the amount (mg) of FC-9S in 27.S ml (25 ml added plus 2.5 ml remaining from previous step) of soluxum in each respective step and then subtracting the amount (mg) in the 2.5 ml of solution remaining from the previous step. E1D108765 coooio 8< FC 143 Data for FC 143 arc presented in TABLE IV and TABLE V and in FIGURE 4. The adsorption isotherm indicated FC 143 mobility similar to that of FC 95 with K=0.38 and N*l. Regression analyses were not performed on the desorp tion isotherms, however, the graphed data (FIGURE 4) indicated that adsorption and desorption could not be described by a single-valued function. That is, the K' and N* values for desorption would not be the same as K and N for adsorption. Subjective evaluation would indicate that the desorption coefficients ic', would be ouch smaller than the adsorption coefficient, K, at solution concentrations greater than about 25 og/1, since the slope of the adsorption isotherm was ouch greater than the slopes of the desorption isotherms in - this range. At solution concentrations less than 25 mg/1., the desorption coefficients would appear to be much greater than the adsorption coefficient. From this it would appear that two or three different binding mechanisms were involved with stronger binding occuring at the higher concentrations and the converse at lower concentrations. While this may indicate a tendency ' for FC 143 to be immobile at high concentrations, it would be quite mobile in any situations involving low concentrations. Material balance data for FC 143 are presented in TABLE VI. While the two concentrations resulting in 212%and 201% desorption (last column in TABLE VI) were erratic, in general, the data indicated that all of the FC 143 was accounted for throughout the experiment. GLK001025 EID108766 0OO0I1 0y TABLE IV FC 143 Adsorption Data A Initial FC 143 Cone.a mg/1. 522.5 292.6 167.2 94.1 52.3 5.2 B Equil. Cone., C, mg/1. 485.8 279.1 160.3 92.2 49.9 5.1 C Z Removed By Soil ( x 100) 7.0 4.6 4.1 2.0 4.5 1.9 D. E , Total FC 143 in Initial Sol'n, tug (A x 0.025 liters) Total FC 143 in Sol'n at Equil., mg (B x 0.025 liters) 13.0625 7.3150 4.1800 2.3525 1.3075 0.1300 12.1450 6.9775 4.0075 2.3050 1.2475 0.1275 F FC 143 Adsorbed on Soil, x/m, pg/g (D-E) X M T pg/mg _________ ? 183.5 67.5 34.5 9.5 12.0 0.5 GLK001026 EID108767 000012 TABLE V FC 143 Desorption Isotherm Data* AB Equil. Cone, in Solution, C, mg/1 Equil. Cone. in first Desorptlon Solution, mg/1. (Column B, Table IV) 485.800 279.100 160.300 92.200 49.900 5.100 47.6000 28.8000 17.2000 10.7000 6.1000 0.6000 CD Equil. Cone. Equil. Cone. In Second Desorp- in Third Desorption tion Solution, mg/1. solution, mg/1. 6.80000 4.80000 3.40000 2.00000 0.80000 0.10000 3.50000 2.90000 2.00000 0.50000 0.20000 0.01000 EF Amount Adsorbed Amount on Soil on Soil, x/m, us/g .M&ZgAfter First Desorp_______ Lion (Column F. TABLE IV) 183.500 67.500 34.500 9.500 12.000 0.500 164.600 50.850 20.050 -3.250 3.400 -0.250 GH Amount on Soil Amount on Soil After Second Desorp- After Third Desorp- Mg/E *ion pg/g tion 151.000 38.650 9.950 -8.900 2.050 -0.500 135.150 25.100 0.650 -10.650 1.350 -0.505 Columns F, G, and H were calculated In the same way as Column F, TABLE XV with correction for the amount of FC 143 in the 2.5 ml of solution remaining from the previous step in each case (See Materials and Methods Section). GLK001027 EID 108768 C00013 Adsorbed on Soil, x/m, ug/g. 11 >, i Equil. Cone., C, mg/1 FIGURE 4 FC 143 ADSORPTION AND DESORPTION ISOTHERMS Solid line is best fit adsorption isotherm. Dotted lines are estimated desorption isotherms. A's are adsorption isotherm data points. B, C, D, E, and F are desorption data points for the respective concentrations. GENERAL COMMENTS The FC 95 and FC 143 adsorption coefficients from these experiments may be converted to the analogous constants based on soil organic carbon contend Kqc, with the equation Kqc = 100 K/(% organic carbon) giving a Kqc of 45 for FC 95 and 17 for FC 143 (2.2% organic carbon for this soil). Comparing these values to those in TABLE VII, it can be seen that FC 95 and FC 143 are at the low end of the spectrum, again indicating high mobility of these compounds. EIDl08769 C00014 GLK001028 12 TABLE VI FC 143 MATERIAL BALANCE* A Total FC 143 Initially in Solution mg. (Column D, Table IV) 13.0625 7.3150 4.1800 2.3525 1.3075 0.1300 D Amount Removed by First Desorption, mg. 0.09450 0.08325 0.07225 0.06375 0.04300 0.00375 G Total Amount Desorbed by Three Desorptions, mg (D+E+F) 0.2418 0.2120 0.1693 0.1008 0.0535 0.0050 B FC 143 in Solution at Equil., mg. (Column E, TABLE IV) C FC 143 on Soil at Equil., mg. (A - B) 12.1450 6.9775 4.0075 2.3050 1.2475 0.1275 E Amount Removed by Second Desorption, mg. 0.06800 0.06100 0.05050 0.02825 0.00675 0.00125 H Amount Remaining on Soil After 3 Desorptions, mg. (C - G ) 0.676750 0.125500 0.003250 -0.053250 0.006750 -0.002525 0.9175 0.3375 0.1725 0.0475 0.0600 0.0025 F Aaount Removed by Third Desorption, mg 0.079250 0.066750 0.046500 0.008750 0.003500 0.000025 I Amount Desorbed as percent of Amount Ad sorbed (G/C x 100) 26.549 62.81S 98.116 212.105 88.750 201.000 `Columns D, E, and F were obtained by first calculating the aaount (mg) of FC 143 in 27.5 ml (25 ml added plus 2.5 ml remaining from previous step) of solution in each respective step and then subtracting the aaount (mg) in the 2.S ml of solution remaining from the previous step. EID 108770 00015 GLK001029 13 TABLE Vil Comparison of Adsorption Coefficients for a Selected Group of Pesticides (Hamakcr and Thompson, 1972) Chemical Kor (mobile) (immobile) Chlorarabcn 12.8 (FC 1 4 3 ................ 17) 2,4-0 32 (FC 95 ................. 45) Propham SI Bromacil 71 Monuron 83 Simazine 135 Propazine 152 Dichlobenil 164 Atrazine 172 Chloroprupham 245 Prometone 300 Ametryn 380 Diuron 485 Prometryne 513 Chloroxuron 4,986 Paraquat 20,000 DDT 243,000 The small amounts adsorbed and ease of desorption is consistent with the relatively high water solubility of FC 95 (300 mg/1) and Fc 143 (>20 g/1.) and with the chemical nature of the molecules - organic salts which ionize in aqueous solution: C8F17S03V C7FiSC2-NH4* ' FC 95 FC 143 EID108771 0.00016 GLK001030 Terms DPM - Disintegrations per minute C - Concentration of chemical in solution at equilibrium x/m - Concentration of chemical adsorbed on soil at equilibrium R2 -Coefficient of determination K - Adsorption coefficient K' -Desorption coefficient N -Exponential term in FreundlichEquation N' -Exponential term for desorption equation Kqc - Adsorption coefficient based on soil organic carbon content References Davidson, J. M., et. al., 1975, Use of Soil Parameters for Describing Pesticide Movement Through Soils, U. S. EPA, EPA-660/2-75-009. Davidson, J. M., 1976, "Vertical Movement and Distribution of Organics in Soils," presented at Symposium on Nonbiological Transport and Transformation of Pollutants on Land and Water, at National Bureau of Standards, Gaithersburg, MD ., May 11-13, 1976. Hamaker, J. W. and J. M. Thompson, 1972. "Adsorption" in Organic Chemicals in the Soil Environment. C. A. I. Goring and J. W. Hamaker (eds.J. Marcel Dekker, Inc., N. Y. Hamaker, J. W., 1975, "Interpretation of Soil Leaching Experiments," in Chemicals, Human Health and the Environment, A Collection of Dow Scienti fic Papers, Vol. 1, Dow Chemical USA', Midland, Mich. 58640 EID108772 000017 GLK001031