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Aging Effects on the Sorption–Desorption Characteristics of Anthropogenic Organic Compounds in Soil
Author(s) -
Sharer Michael,
Park JeongHun,
Voice Thomas C.,
Boyd Stephen A.
Publication year - 2003
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2003.1385
Subject(s) - chlorobenzene , sorption , desorption , chemistry , environmental chemistry , loam , ethylene , soil water , atrazine , pesticide , organic chemistry , adsorption , soil science , catalysis , environmental science , ecology , biology
Field studies have demonstrated that prolonged pesticide–soil contact times (aging) may lead to unexpected persistence of these compounds in the environment. Although this phenomenon is well documented in the field, there have been very few controlled laboratory studies that have tested the effects of long‐term aging and the role of differing sorbates on contaminant sorption–desorption behavior and fate in soils. This study examines the sorption–desorption behavior of chlorobenzene, ethylene dibromide (1,2‐dibromomethane), atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐ s ‐triazine), and 2,4‐D (2,4‐dichlorophenoxyacetic acid) on one soil type after 1 d, 30 d, and 14 mo of aging. Sorption isotherms were evaluated after each aging period to observe changes in the uptake of each compound by soil. Desorption kinetic data were generated after each aging period to observe changes in release from soil, and desorption parameters were evaluated using a three‐site desorption model that includes equilibrium, nonequilibrium, and nondesorption sites. The data indicate no statistically significant increase in sorption for ethylene dibromide or chlorobenzene from 1 to 30 d, although sorption of 2,4‐D increased slightly, and sorption of atrazine decreased slightly. Statistically significant increases in linear sorption coefficients ( K d ), from 1 d to 14 mo of aging, were apparent for ethylene dibromide and 2,4‐D. The K d values for chlorobenzene, measured after 1 d, 30 d, and 14 mo of aging, were statistically indistinguishable. Aging affected the distribution of chemicals within sorption sites. With aging, the desorbable fraction decreased and the nondesorbable fraction, which was apparent after only 1 d of pesticide–soil contact, increased for all chemicals studied.