Concentrations and Bioavailability of Heavy Metals in Sediments of Riverine Wetlands Located in the Huaihe River Watershed, China

Abstract

Fractionations and mobility of heavy metals in sediment cores taken from the Suoxu River located in the Huaihe River watershed, China, were carried out and assessed. The results revealed that the total concentrations of Cd, Cr, Cu, Pb, and Zn reached up to 0.38, 70.2, 92.1, 35.9, and 227.0 mg kg−1 in sediment cores from the upstream, 0.19, 66.5, 27.4, 29.1, and 80.1 mg kg−1 from the midstream and 0.18, 49.4, 24.2, 28.5, and 64.8 mg kg−1 from downstream of the river, respectively. The concentrations of heavy metals near the surface of sediment cores from the upstream were significantly higher compared to the bottom and the downstream of the river. Significant positive correlations between total organic carbon and metals suggested that heavy metals tended to be adsorbed by organic material, especially in sediment cores from the upstream of the river possessing high concentrations of organic matter. In addition, the geoaccumulation index (Igeo) values of deep sediment samples were lower than those of surficial sediment samples and increased drastically from about 4 cm depth layer. Igeo values greater than 1 in the upper layer of sediments from the upstream of the river revealed that the upper stream of the Suoxu River was exposed to moderate pollution. The increase of metal concentrations was connected with the inflow of the contaminated water from industrial effluents and domestic sewage. Finally, the sequential extraction after the European Communities Bureau of Reference procedure indicated that Cd was primarily bound to acid extractable fractions with a percentage from 47.4 to 63.8%, 51.1 to 73.3%, and 47.5 to 71.9% in the three sediment profiles, respectively. The upstream of the river was exposed to toxicity of Cd for the significant mobility. Cu and Pb possessed potential bioavailability because of the association with reducible and oxidizable species and could be released and entered into the food chain, whereas Cr and Zn displayed weak mobility because of the connection with residual fractions, concluded from the largest proportions accounting for total concentrations.

Microbeads in Commercial Facial Cleansers: Threatening the Environment

“…This lowest APD value of MB‐B, together with its highest value of Span (2.464 ± 0.448) indicated a lack of homogeneity in size for the smallest microbeads tested, which would make them more likely to be ingested by filter‐feeding bivalves and small planktonic organisms, accumulating at higher levels of the food chain. Besides this fact, a smaller particle size could offer a higher adsorption capacity for different pollutants . In addition, MB‐B was the cheapest of the four brands tested, which makes it a particularly attractive option for consumers.…”

“…It is also known that particle size is an important factor affecting the concentration of their associated pollutants [23]. The results of this study revealed that the highest concentration of heavy metals was measured in microbeads with the lowest APD; that is, MB-B and MB-A, accounting for 93.9% of total heavy metals in bi-distilled water and 74.4% of total heavy metals in TUE, where the interference of residual organic matter could act as a sorption competitor for microbeads.…”

Heavy metal concentrations in riparian soils along the Han River, China: The importance of soil properties, topography and upland land use

“…It is well established that soil organic matter is positively correlated with available heavy metal contents and represents an important heavy metal sink (Ferraz et al, 2000;Bartoli et al, 2012;Yuan et al, 2015). Soil organic matter, a complex and heterogeneous component initially ascribing to the physical, chemical and biological evolution of biopolymeric materials, is further decomposed to fulvic and humic acids, kerogen and black carbonaceous materials via various degrees of diagenetic processes (Zhang et al, 2014).…”

Improved Calculations of Heavy Metal Toxicity Coefficients for Evaluating Potential Ecological Risk in Sediments Based on Seven Major Chinese Water Systems

“… Note: The data required in the table are all derived from previous research [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ]. “—” represents that relevant data could not be found in the literature.…”