Effects of Soil Amendments on Arsenic Uptake by Earthworms(Eisenia fetida) in Arsenic-Polluted Soil

Abstract

This study was conducted to evaluate the effects of soil amendments on arsenic (As) bioavailability in As-polluted soils. We determined the subsequent changes in As toxicity toward earthworms (<i>Eisenia fetida</i>) and As uptake by earthworms. We also investigated whether As bioaccumulation could be used as an index to evaluate changes in quality of As-polluted soils. No significant changes in acute toxicity to earthworms were observed, and the observed increases (70-93 mg kg<sup>-1</sup>) or decreases (27-38 mg kg<sup>-1</sup>) in bioavailable As in soils at the end of test were not related to the As concentrations in earthworms. The As concentration in earthworms 14 days after exposure was significantly lower in calcium superphosphate (CSP)- and S-treated soils (101.4-112.8 mg kg<sup>-1</sup>) than in control soil (138.9 mg kg<sup>-1</sup>), probably owing to reduced earthworm growth due to lower pH in CSP- and S-treated soils (6.3-7.3) relative to control and steel slag-treated soils (7.5-8.4). Comparisons of As toxicity and the effects of soil properties on this toxicity toward various species of earthworms could facilitate the use of earthworms to produce biological indices for evaluating changes in quality of As-polluted soils following amendment treatments.