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Availability of metals to the nematode Caenorhabditis elegans : Toxicity based on total concentrations in soil and extracted fractions
Author(s) -
Boyd Windy A.,
Williams Phillip L.
Publication year - 2003
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620220518
Subject(s) - environmental chemistry , soil water , organic matter , chemistry , soil test , extraction (chemistry) , environmental science , metal , ecotoxicology , soil contamination , calcium carbonate , soil science , organic chemistry , chromatography
Current regulation of metals in soils is based on total metal concentrations rather than on actual exposure concentrations. Considering the extreme variation in soil physicochemical properties, total concentrations are not reflective of the availability and resultant toxicity of metals in different soils. In this study, the availability of Cd, Cu, Ni, Pb, and Zn to the free‐living soil nematode Caenorhabditis elegans was assessed after 24‐h exposures in three soils using a sequential soil extraction procedure. Albany soil, sampled from southern Georgia, USA, is characterized by a high sand content, whereas Cecil soil from the Piedmont region of Georgia contains higher fractions of clay and organic matter. The final soil was an American Society for Testing and Materials (ASTM) artificial medium composed of peat, kaolin clay, sand, and calcium carbonate. Based on their composition, ASTM medium would sorb metals most strongly and Albany soil the least strongly. In fact, 24‐h lethal concentrations to 50% (LC50s) of nematodes for the five metals as determined by the total metal concentration followed this trend. In addition, water‐extractable metals were lowest in ASTM medium and highest in Albany soil when spiked at the same concentrations. Our data show the need to consider soil type when performing toxicological tests and establishing site‐specific allowable metal concentrations in soil.