IntroductionRapid urbanization and industrialization provide benefits to the economy and society but also cause pollution of soil, water, and air and even pose risks to ecosystems [1][2][3][4]. Heavy metals refer to metals and metalloids, such as Cr, Cu, Zn, As, Cd, Ni, Pb, and Hg, whose densities are > 5 g•cm −3 [5][6]. Heavy metals in soil are difficult to degrade and enter the food chain. Consequently, heavy metal pollution will not only reduce the quality of the soil environment but also pose a threat to human health [7][8][9][10][11][12]. For instance, exposure to As can lead to dermal lesions, skin cancer, peripheral neuropathy, and peripheral vascular disease
Riparian vegetated filter strips (RVFS) can effectively intercept agricultural non-point source pollution (ANSP) into a water body and reduce the risk of water body pollution. The present study evaluates the long-term effectiveness of different types and lengths (5 m, 9 m, 13 m) of RVFS in reducing the suspended solids (SS) and nutrients from agricultural runoff. Three field experimental plots (T1-T2-T3) planted with weeds, sweet clover (Melilotus suaveolens L.) and sweet clover/Chinese wingnut (Pterocarya stenoptera C. DC.) were established adjacent to the agricultural edge from 2011 to 2018. The runoff volumes, SS, and nutrients concentrations were determined at each effective runoff event during the study periods. The results indicated that all RVFS (T1, T2, and T3) reduced the mass of the nutrients rather than the concentration in all runoff events. In the rainfall events, the pollutants were reduced significantly in the presence of RVFS. The removal efficiency of T2 and T3 amounted to 79% and 84% for SS within the first 5 m, which was significantly higher than T1(61%). The 9 m-long T3 caused a significant reduction in the mean total phosphorus (TP) and dissolved phosphorus (DP) by 84% and 82%, respectively. More than 70% of the pollutants from rainfall runoff could be controlled by a 13 m RVFS. The snow-melt events increased the risk of ANSP migrating to streams, especially for the DP. However, the Chinese wingnut strip increased the filtering capacity of the DP as compared
In this study, a total of 26 surface sediments samples are collected from the Liao River estuary wetland, China. The concentration, potential ecological risk, and source apportionment of potentially toxic metals including Sr, Zn, Cr, Ni, Pb, Cu, and As in different seasons are analyzed. The average concentrations of potentially toxic metals are below the first class of Chinese marine sediment quality standard. There is no significant difference in the concentrations of potentially toxic metals in the sediments collected in June and November. The concentrations of potentially toxic metals in the periphery of the nature reserve are higher than those in the core area of the nature reserve. The average enrichment factors of As, Pb, Cu, Ni, Zn, and Cr are about 1, classified as minimal enrichment. The average enrichment factor of Sr is >2, which corresponds to moderate enrichment. The individual (E r ) and total potential ecological risks (RI) of potentially toxic metals are low. The positive matrix factorization model suggested that the potentially toxic metals in surface sediments in June are dominantly from atmospheric deposition, industrial discharges, natural sources, and traffic emission. However, the traffic emission source is replaced by agricultural production and metal smelting activities in November.
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