Release of Heavy Metals and Metalloids from Two Contaminated Soils to Surface Runoff in Southern China: A Simulated-Rainfall Experiment

Abstract

The release of heavy metals and metalloids (HMs), including Pb, Zn, Cd, As, and Cu, from two typical contaminated soils with different properties, namely red soil and limestone-dominated soil, was characterized through simulated-rainfall experiments in order to investigate the effects of soil properties on HM release. Significant differences in the HM concentrations between the two soils resulted in various concentrations of dissolved and particulate HMs in the runoff. Differences in the dissolved HM concentrations in the runoff were inconsistent with the HM concentrations in the soils, which is attributed to the variable solubilities of HMs in the two soils. However, the HM enrichment ratios were not significantly different. The strong correlation between dissolved organic carbon and dissolved HMs in the runoff, and between the total organic carbon and particulate HMs in sediments, were observed, especially in the limestone-dominated soil. The specific surface area and HM concentrations in sediments were weakly correlated. Acid-rainfall experiments showed that only the limestone-dominated soil buffered the effects of acid rain on the runoff; the concentrations of dissolved Pb, Zn, Cd, and Cu increased in the red soil under acid rainfall and were 60, 29, 25, and 19 times higher, respectively, than under the neutral conditions. The results contribute to the understanding of HM behavior in the two typical soils in southern China, exposed to frequent storms that are often dominated by acid rainfall.

Elemental mobilisation by sheet erosion affected by soil organic carbon and water fluxes along a radiotraced soil catena with two contrasting parent materials

“…Despite the US having the steepest slopes observed, the dense vegetation cover also favours soil infiltration, inhibits surface runoff and reduces the flow accumulation and the subsequent detachment of soil particles by water, which results in less mobilisation of elements. As reported by other authors (Ramos et al, 2019;Wei et al, 2019) using simulated-rainfall experiments, a relatively higher soil hydraulic conductivity results in more infiltration, and consequently, less surface runoff affects the release and migration of heavy metals and metalloids.…”

“…4), suggesting that Sr can be sorbed in hydrated form by clay minerals, resulting in higher Sr contents than in the US. Besides, the accumulation of Sr in the cultivated fields at the end of LS indicates that Sr is mobilised along the slope in association with soil particles as the soil redistribution rates support, though its enrichment may also be related to a local source of soil contamination such as phosphate fertilisers (Wei et al, 2019).…”

Wide Riparian Zones Inhibited Trace Element Loss in Mining Wastelands by Reducing Surface Runoff and Trace Elements in Sediment

“…The loss of soil and trace elements in the experimental field was comparable to that in the manganese tailings area [ 31 ]. The concentrations of trace elements in sediment and dissolved trace elements in runoff were closely correlated with the content and solubility of trace elements in the soil [ 32 ]. Organic matter alters the surface properties of soil particles, diminishing the internal repulsive force and enhancing the stability and erosion resistance of soil aggregates [ 33 ].…”

Insight into functional microorganisms in wet–dry conversion to alleviate the toxicity of chromium fractions in red soil

“…The unique tropical and subtropical monsoon climate in southern China brings abundant rainfall and distinct fractions between the rainy and dry seasons ( Cao et al, 2006 ). The formation of red soil in South China is related to the abundant rainfall ( Huang et al, 2015 ; Wei et al, 2019 ). The red soil, accounting for approximately 11% of the total area of China, is an important soil resource in the tropical and subtropical regions of China ( Li et al, 2007 ; Zhang et al, 2018 ).…”