Main controlling factors and forecasting models of lead accumulation in earthworms based on low-level lead-contaminated soils

Tang, Ronggui; Ding, Changfeng; Ma, Yibing; Wan, Mengxue; Zhang, Taolin; Wang, Xingxiang

Main controlling factors and forecasting models of lead accumulation in earthworms based on low-level lead-contaminated soils

2018

To explore the main controlling factors in soil and build a predictive model between the lead concentrations in earthworms (Pbₑₐᵣₜₕwₒᵣₘ) and the soil physicochemical parameters, 13 soils with low level of lead contamination were used to conduct toxicity experiments using earthworms. The results indicated that a relatively high bioaccumulation factor appeared in the soils with low pH values. The lead concentrations between earthworms and soils after log transformation had a significantly positive correlation (R² = 0.46, P < 0.0001, n = 39). Stepwise multiple linear regression analysis derived a fitting empirical model between Pbₑₐᵣₜₕwₒᵣₘ and the soil physicochemical properties: log(Pbₑₐᵣₜₕwₒᵣₘ) = 0.96log(Pbₛₒᵢₗ) − 0.74log(OC) − 0.22pH + 0.95, (R² = 0.66, n = 39). Furthermore, path analysis confirmed that the Pb concentrations in the soil (Pbₛₒᵢₗ), soil pH, and soil organic carbon (OC) were the primary controlling factors of Pbₑₐᵣₜₕwₒᵣₘ with high pathway parameters (0.71, − 0.51, and − 0.49, respectively). The predictive model based on Pbₑₐᵣₜₕwₒᵣₘ in a nationwide range of soils with low-level lead contamination could provide a reference for the establishment of safety thresholds in Pb-contaminated soils from the perspective of soil-animal systems.

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