The toxicity of exogenous arsenic to soil-dwelling springtail Folsomia Candida in relation to soil properties and aging time

摘要

Arsenic (As) is a toxic metalloid, but studies on As toxicity to soil-dwelling springtails are fairly limited, and did not consider the effects of various soil properties and long aging time. To address this, the toxicity of As to model organism-Folsomia candida were evaluated in the laboratory studies. The results showed that compared to the soils aged only for 15 d, the concentrations inhibiting 50% reproduction (EC50) significantly increased by 1.3- to 2.0-fold in four soils aged for 150 d, the concentrations causing 50% mortality (LC50) were higher than the highest test concentration in the most soils. Furthermore, the aging effects correlated significantly with soil free Fe oxides contents. The toxicity of As differed in ten soils aged for 150 d, the LC50 were 320 - 1280 mg/kg in acute test and the EC50 were 67-580 mg/kg in chronic test. Regression analysis indicated that soil clay was the most important single factor predicting soil As toxicity to reproduction, explaining 89% of the variance in EC50 values. Soil pH, free Fe oxides and Al oxides could also well explain the toxicity variance ( 65%), indicating that As sorption was a key factor controlling its toxicity.