Fractionation and release of Cd, Cu, Pb, Mn, and Zn from historically contaminated river sediment in Southern China: Effect of time and pH

Abstract

The release of in situ heavy metals (cadmium [Cd], copper [Cu], lead [Pb], manganese [Mn], and zinc [Zn]) from contaminated river sediment near a Cu-iron mine in South China was experimentally studied. The effects of pH values and the kinetics of heavy metal release were investigated. In addition, species of the 5 metals in the sediment were determined as a function of pH and time. Rates and extents of metal desorption were studied over 30 d, and a 3-parameter, 2-compartment model was used to analyze the desorption kinetics. The rate constants (k s ) for the slowly desorbing fraction of heavy metals were found to be 5 to 6 orders of magnitude lower than the corresponding rate constants (k r ) for the rapidly desorbing fraction, suggesting that slow desorption is the rate-limiting step. The partition coefficients (K d ) varied significantly among metals, on the order Pb > Cu >Zn > Cd > Mn, indicating that the sediment had a much higher retention capability for strongly hydrolyzed metals than for weakly hydrolyzed ones. The amount of metals released from the sediment decreased dramatically at the final pH of 2 to 4 and leveled off in the pH range of 5 to 8. Release time and pH exhibited a varied influence on the fractionation of metals, and had a more remarkable influence on more mobile fractions and hardly any effect on the residual fraction during the desorption process. The fractionation of strongly adsorbing metals like Pb was not as dependent on release time and pH as it was for the weakly bonded metals like Mn and Cd. The results indicate that in situ heavy metals may exhibit a sustainable potential for release and may increase health risks when the pH of the river is lowered. Environ Toxicol Chem 2019;38:464-473. C 2018 SETAC.

Removal and Separation of Heavy Metal Ions from Multicomponent Simulated Waters Using Silica/Polyethyleneimine Composite Microparticles

“…The increase of goods production due to the increase of world population has raised subsequent problems, such as the release of organic and/or inorganic compounds into the environment. Water, the most spread solvent around the globe, interacts/dissolves these substances, acting like a cleaning agent . In many countries, there is a growing need for development of more efficient materials for water treatment and purification technologies (chemical precipitation, flocculation, reverse osmosis, solvent extraction, sorption, membrane processes, exchange of ions, etc.…”

Contaminated aquatic sediments

“…Resuspension of fine surficial sediment during the dry season resulted in higher particulate metal concentrations in the water, and metal adsorption onto fine surficial sediment was favored mainly by Fe/Mn oxyhydrides. Xu, Huang, Huang, Liu, and Shu (2019) studied the in situ release of heavy metals from sediment in a South China River located near a Cu mine. They observed a biphasic pattern in metal desorption rates and noted that more hydrolyzed metals had a higher affinity for the sediment than the less hydrolyzed ones.…”

Quantifying Source Apportionment, Co‐occurrence, and Ecotoxicological Risk of Metals from Upstream, Lower Midstream, and Downstream River Segments, Bangladesh

“…Appraisal of metal contamination status, co‐occurrence networks, source apportionment, and ecotoxicological risk evaluation (which are important environmental determinants) is essential for constructing efficient water security regulation and management strategies on a national basin scale. Several studies have appraised the pollution status and ecotoxicological risks of metals in riverine sediments in different parts of the world, for instance, Ustaoğlua and Islam (2020) in Giresun, Northeast Turkey, and Ji et al (2019) in Baiyangdian Lake, China (also see Bhuiyan et al 2017; Xu et al 2019; Khan et al 2020; Xia et al 2020). To determine different metal concentrations, numerous indices have been constructed, such as the geo‐accumulation index (Igeo), enrichment factor, risk index, and toxicity unit in riverine sediments (Siddiqui and Pandey 2019; Niu et al 2020).…”