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An enriched stable isotope technique to estimate the availability of soil zinc to Lumbricus terrestris (L.) across a salinization gradient
Author(s) -
Rodgers Derek W.,
Lev Steven M.,
Snodgrass Joel W.,
Ownby David R.,
Prince Lisa M.,
Casey Ryan E.
Publication year - 2011
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.421
Subject(s) - lumbricus terrestris , bioavailability , earthworm , soil water , environmental chemistry , chemistry , amendment , zinc , ecology , soil science , environmental science , biology , bioinformatics , organic chemistry , political science , law
Abstract An enriched stable isotope approach was developed to evaluate Zn bioavailability to Lumbricus terrestris . The decrease in 68 Zn/ 66 Zn in organ tissues was used to assess the relative magnitude of the bioavailable soil Zn pool. This tool was then used to specifically evaluate bioavailability as a function of soil cation distribution. Storm‐water pond soils were modified using two treatment regimens whereby H 2 O‐extractable Zn was varied either by different ZnCl 2 amendments or by constant ZnCl 2 amendment followed by varying the soil cation distribution through salt amendments (NaCl or CaCl 2 ). Earthworms previously equilibrated in 68 Zn‐spiked soil were introduced to experimental soils, and after 2 d, removed for analysis of isotopic ratios in specific tissues. Despite a wide range of H 2 O‐extractable Zn values produced by the salt treatments (0.007–24.3 mg/kg), a significant relationship between Zn turnover rate in earthworm tissues and H 2 O‐extractable Zn in the salt‐treated soils was not observed. Rather, considering both treatment regimens, turnover rate better correlated with Zn present in broader pools, such as that extracted by 6M HNO 3 . The bioavailability of trace metals to earthworms may be poorly characterized by loosely bound fractions such as the pore water. Additionally, the turnover rate of 68 Zn in anterior organ tissues may be an effective tool to evaluate the relative magnitude of the bioavailable soil Zn pool. Environ. Toxicol. Chem. 2011; 30:607–615. © 2010 SETAC