Relationship between Bulk Metal Concentration and Bioavailability in Tropic Estuarine Sediments

Abstract

elements, their chemical forms and the mineral composition, organic matter (TOC) and carbonates (TIC) in surface sediments from the Cai River estuary and Nha Trang Bay were first determined along the salinity gradient. The abundance and ratio of major and trace elements in surface sediments are discussed in relation to the mineralogy, grain size, depositional conditions, reference background and SQG values. Most trace-element contents are at natural levels and are derived from the composition of rocks and soils in the watershed. A severe enrichment of Ag is most likely derived from metal-rich detrital heavy minerals such as Ag-sulphosalts. Along the salinity gradient, several zones of metal enrichment occur in surface sediments because of the geochemical fractionation of the riverine material. The parts of actually and potentially bioavailable forms (isolated by four single chemical reagent extractions) are most elevated for Mn and Pb (up to 36% and 32% of the total content, respectively). The possible anthropogenic input of Pb in the region requires further study. Overall, the most bioavailable parts of trace elements are associated with easily soluble amorphous Fe and Mn oxyhydroxides. The sediments are primarily enriched with bioavailable metal forms in the riverine part of the estuary. Natural (such as turbidities) and human-generated (such as urban and industrial activities) pressures are shown to influence the abundance and speciation of potential contaminants and therefore change their bioavailability in this estuarine system.

Enhancement in adsorption potential of microplastics in sewage sludge for metal pollutants after the wastewater treatment process

“…MPs act as vectors for pollutants due to their large specific surface area, and pose a potential threat to the environment (Koelmans et al 2016). Field studies have indicated that persistent organic pollutants (POPs) and metal pollutants adhere to the MPs (Chen et al 2018a, Koukina et al 2016, Wang et al 2017. Organic pollutants adsorbed on the MPs include dichlorodiphenyltrichloroethane, and phenylalanine 17 alpha ethinyl estradiol, etc.…”