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Abstract Nickel (Ni) is a toxic metal, but studies on Ni toxicity to soil-dwelling springtail are fairly limited, and did not consider the effects of various soil properties and long aging time. To address this, the chronic toxicity of Ni to model organism— Folsomia candida in relation to soil properties and aging time were evaluated in the laboratory study. The results showed that compared to the soils aged only for 7 d, the concentrations causing 50% mortality (LC 50) and inhibiting 50% reproduction (EC 50) basing measured total Ni in four soils aged for 120 d increased by 1.30–1.94 fold and 1.27–1.82 fold, respectively. Furthermore, the aging effects significantly correlated with soil pH. The toxicity values of Ni differed in ten soils aged for 120 d, the LC 50 values were 279–4025 mg/kg and the EC 50 values were 133–1148 mg/kg. When calculating the toxicity values basing water soluble and CaCl 2 extracted Ni, the variations in LC 50 values between ten soils decreased, while the variations in EC 50 values increased. Regression analysis indicated that soil pH was the most important single factor predicting soil Ni toxicity to springtail, the combination of soil pH and OM could best explain Ni toxicity variance in ten soils (89.1% of the variance in LC 50 values and 89.6% of the variance in EC 50 values). Highlights • Prediction models of Ni toxicity to springtail basing soil properties were developed. • Soil pH was the most important single factor predicting Ni toxicity to springtail. • Aging effects on Ni toxicity to springtail significantly correlated with soil pH. • Water soluble and CaCl 2 extracted Ni were not completely adequate to explain Ni toxicity differences between soils. [ABSTRACT FROM AUTHOR]

Abstract Chromium (Cr) is a well-known toxic metal, but studies on Cr 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 chronic toxicity of Cr(VI) to survival and reproduction of model organism— Folsomia candida were evaluated in the laboratory studies. The results showed that compared to the soils aged only for 2 and 21 d, the concentrations inhibiting 50% reproduction (EC 50) significantly increased by 2.8–5.2 fold and 1.7–2.6 fold, the concentrations causing 50% mortality (LC 50) were higher than the highest test concentration in four soils aged for 150 d. Furthermore, the aging effects correlated significantly with soil amorphous Fe oxides. The EC 50 values of Cr significantly differed in ten soils aged for 150 d, ranging from 27 to 512 mg kg−1, which were associated with the variations in reduction and sorption capacity in different soils. Regression analysis indicated that soil clay was the most important single factor predicting soil Cr toxicity to reproduction, and the inclusion of cation exchange capacity in the clay regression could best explain the toxicity variance (87.2%). Additionally, soil pH, organic matter and amorphous Fe oxides could also well explain the toxicity variance (>55%). Highlights • Prediction models of Cr toxicity to springtail as a function of soil properties were developed. • Soil clay was the most important single factor predicting soil Cr toxicity to springtail. • Toxicity of Cr to springtail decreased significantly after aging for 150 d. • Decreased toxicity with increasing aging in Cr(VI)-treated soil closely related to Cr(VI) reduction. [ABSTRACT FROM AUTHOR]

Abstract 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 (EC 50) significantly increased by 1.3- to 2.0-fold in four soils aged for 150 d, the concentrations causing 50% mortality (LC 50) 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 LC 50 were 320–> 1280 mg/kg in acute test and the EC 50 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 EC 50 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. Highlights • Toxicity of As to springtail decreased significantly after aging for 150 d. • The effects of aging on As toxicity to springtail correlated significantly with free Fe oxides. • Prediction models of As toxicity to springtail as a function of soil properties were developed. • Soil clay was the most important single factor predicting soil As toxicity to springtails. [ABSTRACT FROM AUTHOR]

The most existing studies on the toxicity of antimony (Sb) were performed in limited types of soil and after short aging time. Effects of soil properties and long aging time on chronic toxicity of Sb(III) and Sb(V) to model organism Folsomia candida were studied in the laboratory studies. The results showed that after the Sb(V)-treated soils were aged for 365 d, the Sb exhibited no toxicity to survival and reproduction even at the nominal highest concentration of 12,800 mg kg−1 in ten types of soils with distinct differences in soil properties. In the Sb(III)-treated ten soils aged only for 30 d, the concentrations causing 50% mortality (LC 50) and concentrations inhibiting 50% reproduction (EC 50) were 1288–3219 mg kg−1 and 683–1829 mg kg−1, respectively. The LC 50 were higher than the highest test concentration and the EC 50 significantly increased by 2.24–6.16 fold after the Sb(III)-treated soils were aged for 150 d, and soil pH was the most important single factor explaining the variance in aging effects. After the aging time was 365 d, similar with Sb(V)-treated soils, no toxicity were observed in the most Sb(III)-treated soils, indicating the increasing aging effects with aging time. Regression analysis indicated that the OM and pH were the most important single factor predicting Sb toxicity to reproduction in Sb(III)-treated soils aged for 30 and 150 d, respectively. • Prediction models of Sb toxicity in Sb(III)-treated soil were developed basing soil properties. • pH and OM could well predicted Sb toxicity in Sb(III)-treated soil. • Sb(III) and Sb(V) exhibited no toxicity after aged for 365 d in the most soils. • pH was the most important factor controlling aging effects on Sb toxicity in Sb(III)-treated soil. [ABSTRACT FROM AUTHOR]