STP737

    Prediction of Chemical Mobility in Soil from Sorption Coefficients

    Published: Jan 1981


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    Abstract

    Several methods of evaluation have been proposed to classify the mobility of chemicals through soil. The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) guidelines recommend use of soil columns to assess mobility, whereas the Toxic Substances Control Act (TSCA) guidelines propose the use of soil thin-layer chromatography (TLC). The soil sorption coefficient of a chemical has been recognized as the major factor controlling its mobility; however, confidence in this measurement as a sole means to estimate mobility has not been demonstrated.

    Therefore, column leaching experiments have been conducted which correlate the soil adsorption coefficient with movement. Soil columns, eluted under controlled conditions with 50 hectare cm (20 acre in.) of water, have been studied with nine chemicals and three soil types. A simple relationship has been developed which demonstrates that, when the soil adsorption coefficient is known along with the organic carbon content of the soil, predictions regarding movement by means of leaching can be made.

    Since a standard adsorption coefficient based on organic carbon content, Koc, can be determined independent of other soil properties, prediction of movement of a chemical through any soil is possible if the organic carbon content of the soil is known.

    Keywords:

    chemical mobility, pesticides, adsorption, soil sorption coefficient (, K, oc, ), leaching, soil, aquatic toxicology, hazard assessment


    Author Information:

    McCall, PJ
    Project leader, senior research chemist, research leader, student co-op, chemist, senior research manager, Agricultural Products Department, Dow Chemical Co., Midland, Mich.

    Swann, RL
    Project leader, senior research chemist, research leader, student co-op, chemist, senior research manager, Agricultural Products Department, Dow Chemical Co., Midland, Mich.

    Laskowski, DA
    Project leader, senior research chemist, research leader, student co-op, chemist, senior research manager, Agricultural Products Department, Dow Chemical Co., Midland, Mich.

    Vrona, SA
    Project leader, senior research chemist, research leader, student co-op, chemist, senior research manager, Agricultural Products Department, Dow Chemical Co., Midland, Mich.

    Unger, SM
    Project leader, senior research chemist, research leader, student co-op, chemist, senior research manager, Agricultural Products Department, Dow Chemical Co., Midland, Mich.

    Dishburger, HJ
    Project leader, senior research chemist, research leader, student co-op, chemist, senior research manager, Agricultural Products Department, Dow Chemical Co., Midland, Mich.


    Paper ID: STP34148S

    Committee/Subcommittee: E35.13

    DOI: 10.1520/STP34148S


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