Document ppRe4pBQ8p6kQ7gBDv28LrDJX

SOIL ADSORPTION - REVISED TEST SUBSTANCE____________________________________________ Id en tity: Perfluorooctanesulfonate; m ay also be referred to as P FO S or F C -95. (1 O ctanesulfonic acid, 1,1 ,2 ,2 ,3 ,3 ,4 ,4 ,5,5 ,6 ,6 ,7 ,7 ,8 ,8 ,8 -h e p ta d e c a flu o ro -, potassium salt, C A S # 2 7 9 5 -3 9 -3 ) R em arks: The test substance is a w hite powder. Sam ple was re-crystalized from a production lot o f F C -95. Purity determ ined to be 97.9% by LC /M S , 1H -H M R , 19F-N M R and elem ental analyses techniques. METHOD_____________________________________________________ M ethod: Based on O EC D 106 G LP (Y /N ): Y es Y e a r c o m p leted : 2001. A m ended report issued 2 0 0 2 S ta tis tic a l m eth o d s: Statistical analysis and plotting of the data was done according to O E C D M ethod 106 using M icrosoft Excel. T em p eratu re: Room Tem perature (1 9 -3 0 C ) S to c k an d te s t s o lu tio n p re p a ra tio n : T he test concentrations and conditions w ere determ ined in a Prelim inary experim ent. F or the definitive experim ent, test solutions w ere m ade by diluting a stock solution o f un-radiolabeled Perfluorooctanesulfonate to a final test substance concentration o f approxim ately 0 .5 m g/L in aqueous 0.01 M C aC I2. S o il C h a ra c te ris tic s : Soil Class C lay Source Lot Number Physical D e scrip tio n % Organic Carbon % Sand % S ilt % C !ay CEC (m eq/100g) Kittson County, MN 00-2407 1.00 mm airdried, 0-6" deep 2.6% 16% 22% 62% 54.5 Clay Loam Grand Forks County, ND 00-2405 1.00 mm airdried, 0-6" deep 2.6% 21% 46% 33% 24.7 Sandy Loam R iv e r Sedim ent Grand Forks County, ND Grand Forks County, ND 99-2564 00-2406 1.00 mm air- 1.00 mm air- dried, 0-6" deep dried, 0-6" deep 2.8% 1.3% 58% 39% 22% 42% 20% 19% 23.3 17.5 Dom estic S lu d g e NIST, from Denver, CO POTW 2781 200 mesh, oven-dried, sterilized Not analyzed Not analyzed Not analyzed Not analyzed Not analyzed pH in 0.01 M C a C I2 72 6.0 7 .8 1 7.7 Not analyzed 1 V alu e is fo r pH in w ater not pH in 0.1 M C aC I2 T e s t C o n d itio n s: Adsorption Kinetics: R eplicate study sam ples containing the soils (or sedim ents or sludges) w ere equilibrated by shaking fo r at least 12 hours a t room tem perature with 0.01 M C aC I2. Study sam ples w ere dosed with the test substance a t approxim ately 0 .5 mg/L and placed on an orbital shaker. R eplicate sets o f these study sam ples w ere rem oved at designated tim e points throughout a 4 8 hour tim e period. Study sam ples w ere then prepared and analyzed for the target analyte. The adsorption kinetics w ere determ ined using this data. The last set o f study sam ples (4 8 hour) w ere saved and used for the desorption kinetics portion o f the m ethod. Desorption Kinetics (One concentration): A fter the adsorption kinetics experim ent, the 4 8 hour study sam ples w ere centrifuged and the aqueous phase rem oved. T he volum e o f solution rem oved w as replaced by an equal volum e of 0.01 M C aC I2 without test substance. The new m ixture was agitated until the desorption equilibrium w as reached. During a 48-h o ur period, a t defined tim e intervals, sm all aliquots o f the aqueous phase w ere rem oved and analyzed for the target analyte. The desorption kinetics w ere determ ined using this data. RESULTS Soil Type Clay Clay Loam Sandy Loam River Sediment Domestic Sludge Adsorption Kinetics of PFO S, 1:5 SoikSolution Ratio, 48 Hour Tim e Point A verage Distribution coefficient, K * L/Kg Percentage o f Organic Carbon in S o il Average O rganic Carbon norm alized Adsorption Coefficient, K , L/Kg 18.3 Z 6 704 9.72 2.6 374 35.3 2.8 1260 7.42 1.3 571 <0.120 Not available Not calculable T h e data indicate that adsorption occurred within the first few hours o f exposure and the test substance concentration did not vary significantly a fte r 16 hours. Apparent Desorption Kinetics of PFOS, 1:5 Soil.Solution Ratio, 48 hour Tim e Point So Type Desorption Coefficient, Kd, L/Kg Clay 47.1 Clay Loam 15.8 Sandy Loam 34.9 River Sediment 10.0 Domestic Sludge <237 The river sediment displayed the most desorption at 39% after 4 8 hours. The sludge samples did not desorb a detectable amount of test substance. Desorption that did occur was accomplished rather quickly; after the 8 hour time point the test substance concentration did not vary significantly. A d so rp tio n Iso t lierm s Soli type Log K ^ F K ^ V ", L/Kg Regression constant, 1/n Regression Constant, n Clay 1.40 25.1 0.884 1.13 Clay Loam 1.15 14.0 0.841 1.19 Sandy Loam 1.45 28.2 0.829 1.21 River Sediment 0.939 8.70 0.989 1.01 Domestic Sludge 2.53 338 1.26 0.795 (1 ) Freundlich adsorption coefficient. Th e units for the isotherm assum e that the term n=1. M ore accurately, the units are (pg1'1/n(L )1MKg'1) D esorption Is o th e rm s Soil Type Log K ^ f Clay 2.02 L/Kg 105 Regression Constant; 1/n 0.860 Regression Constant, n 1.16 Clay Loam 1.78 60.2 0.954 1.05 Sandy Loam 1.97 94.0 0.985 1.02 River Sediment 1.65 44.6 1.02 0.981 Domestic Sludge 3.50 3130 0.977 1.02 (2 ) (1 ) Freundlich desorption coefficient. . Th e units fo r th e isotherm assum e th at the term n=1. M ore accurately, th e units are ftig 1"1*,(L )1*'Kg"1) Freundlich adsorption isotherm s relate the am ount o f test substance adsorbed on the soil to the am ount present in the aqueous solution at equilibrium . The values calculated fo r the regression constant indicate that the data obtained for the test substance over two orders o f m agnitude is slightly non-linear. CONCLUSIONS Perfluorooctanesulfonate (P F O S ) appeared to adsorb to all o f the soil/sedim ent/sludge m atrices tested. In either case, adsorption o r desorption, an equilibrium is achieved in less than 2 4 hours, with substantial adsorption (> 5 0 % ) occurring in some o f the tim e 0 sam ples after approxim ately 1-m inute o f contact. S u b m itte r 3M Com pany, Environm ental Laboratory, P .O . Box 3 3331, S t. Paul, M innesota, 55133 DATA QUALITY R e lia b ility : lim iseli ranking 1. REFERENCES___________________________________________________ 3M Technical Report "Soil Adsorption/Desorption Study o f Potassium Perfluorooctanesulfonate (P F O S )". M ark E . Ellefson, Project N um ber E 0 0 -1 311, Final R eport Com pletion D ate June 4, 2 0 0 1 . Am ended Report Com pletion D ate M ay 24 , 2 0 0 2 . OTHER Last C hanged: June 12, 2002