Abstract

This study evaluated the effect of electronic waste (e-waste) recycling activities at a regional center, Guiyu, Guangdong, China on heavy metal pollution in the surrounding waterway system. Surface water and sediment collected from the Lianjiang River and its tributaries were analyzed for concentrations of Cu, Pb, Ni, Cd, Hg, and As. Spatially, heavy metals in water and sediment samples decreased downstream of Lianjiang River from Guiyu to the estuary at Haimen Bay. Temporally, heavy metal concentrations in the surface water were high in the rainy season and low in the dry season. In particular, concentrations of Cu from surface water in the Guiyu area were 2.4 to 131 times the reference background concentration, followed in descending order by Ni, Cd, Pb, Hg, and As. However, when compared with China's Environmental Quality Standard, Cd was considered the most harmful element, followed by Hg, Pb, and Cu. Concentrations of Cu in sediment samples in the Guiyu area were 3.2 to 429 times the reference background concentration, followed by Ni, Hg, Pb, Cd, and As. Our findings suggested that high concentrations of heavy metal observed in Guiyu, Lianjiang River and the Haimen Bay could be attributed to the direct effects of e-waste recycling in Guiyu.

In present work, the solubility of silybin in aqueous dextran solution at the temperature range from (293.15 to 313.15) K was measured by a solid liquid equilibrium method. Experimental results reveal that the solubility of silybin is increased with the increase both in dextran's concentration and temperature. With the increase in dextran's concentration, the transport enthalpy and entropy for silybin from water to aqueous dextran solution are decreased within a negative region. The transport enthalpy is more negative than the entropy term. A modified UNIQUAC model was used to correlate solubility data.

Permian coal measure sandstone fissure water (referred to as “coal measure water,” that is, water in coal measures) is one of the important water sources for industrial and agricultural activities in mining areas. However, the regional high‐pressure grouting, one of the most widely used floor control methods, may affect the coal measure water which is connected with limestone aquifer. This study used Taoyuan mine, a typical coal mine in Huaibei coalfield, as the research area to study the influencing mechanism of a grouting treatment on the hydrogeochemical evolution of coal measure water. The hydrogeochemical characteristics and water‐rock interaction mechanism of the coal measure water before and during the treatment were evaluated using a Piper trigram, ion combination ratio, and hydrogen‐oxygen stable isotope. The anions and cations in the coal measure water before and during the treatment had the same trends at SO42− > HCO3− > Cl− and Na+ > Ca2+ > Mg2+, respectively. Hydrochemical types of coal measure water before treatment were mainly SO4·Cl‐Ca·Mg, SO4·Cl‐Na, and HCO3‐Na, and during treatment they were mainly SO4·Cl‐Na and HCO3‐Na. The formation of chemical components of coal measure water before treatment was mainly caused by carbonate dissolution, sulfate dissolution, and pyrite oxidation. During the treatment, sulfate dissolution and pyrite oxidation were the main geochemical processes, and ion exchange was enhanced. Atmospheric precipitation was the source of all water samples, and all showed an obvious 18O drift.