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Assessment of the toxicity of metals in soils amended with sewage sludge using a chemical speciation technique and a lux ‐based biosensor
Author(s) -
McGrath Steve P.,
Knight Bruce,
Killham Ken,
Preston Sara,
Paton Graeme I.
Publication year - 1999
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.5620180411
Subject(s) - environmental chemistry , soil water , bioavailability , pollutant , chemistry , genetic algorithm , soil pollutants , metal toxicity , ecotoxicology , sewage sludge , environmental science , soil contamination , sewage , heavy metals , soil science , environmental engineering , ecology , biology , bioinformatics , organic chemistry
Currently, regulations regarding the maximum permitted concentrations of metals in soils are based on measurements of the total concentration. However, a range of chemical and biological techniques are being developed to predict the bioavailable component of these pollutants. A lux ‐based biosensor was tested in soil solutions extracted from two field experiments at Braunschweig, Germany, that had the same metal inputs, but differed in pH. The bioluminescence response was found to decline as the free Zn 2+ increased, and both soils fitted the same relationship with soil solution metal concentrations. The EC25 and EC50 derived from this curve were 1.9 and 6.1 mg/L, respectively. In contrast, the response to total Zn concentrations in the bulk soil showed distinct curves for each soil, further highlighting the appropriateness of free Zn 2+ as a toxicity indicator. Other metals were present in the soil, but were unlikely to be toxic, because the observed concentrations were less than their individual toxic threshold values in solution. Bioluminescence‐based biosensors were concluded to possibly offer an inexpensive and rapid technique to evaluate the bioavailability of metals in soil systems. The response of these biosensors can be related to soil solution speciation measurements, and this gives a common basis for expression of toxic thresholds in different soils.