Figure - available from: Journal of Soils and Sediments
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Sediment depth in river #3 (shown in Fig. 1) (the measured depth locations are highlighted as blue dots, and the color map was generated by kernel smoothing with barrier)
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Purpose
Rivers in low plains in the subtropical regions of China, where the population is dense and economies are active and well-developed, might be a large terrestrial carbon pool. This present study of the Sanyang wetlands in Wenzhou, southeastern China, aims to quantitatively estimate the volume of sediments in this region’s polluted river syst...
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Citations
... S1 and S2). The description of the study area can be found in our previous studies (Li et al. 2016. Based on the land uses on both sides along the river that affect the chemical properties of the sediment studied, the sampling locations of the sediment cores were chosen to matched three types of the land uses: (a) both sides of the river section where sediment cores was sampled are residential houses and small industrial facilities (called RI), such as those family-owned leather tanneries and textile and metal hardware factories; (b) both sides were orange plantation (called OP); and (c) one side RI and another OP (called OPRI) . ...
To examine the status and risk of heavy metal pollution in an urban wetland in China, the distribution and speciation of chromium (Cr) and other metals (Cd, Cu, Pb, and Zn) were examined. We investigated the impact of three major land uses (residential and industrial (RI), orange plantation (OP), and mixed OP and RI (OPRI)) on the heavy metal characteristics using sediment cores (0–60 cm below water/sediment interface) collected in Sanyang Wetland, China. It was found that all the metals (Cr, Cd, Cu, Pb, and Zn) had lower concentrations in the top layers but higher contents in the bottom layers of sediments. Species of metals in sediments were dominated by their secondary phase (i.e., exchangeable and carbonate bound, Fe-Mn bound and organic bound) with relatively low contents of primary phase (i.e., residual form), except for Cr in RI affected river sediments that had a relatively high content of primary phase (20.97–36.07%). The ratio of secondary phase to primary phase (RSP) and risk assessment code (RAC) methods were applied to assess environmental risk. The results implied that the metal mobility and bioavailability could significantly cause urban wetland environmental quality decline, and thus enhanced strategies should be required to target the capture and removal of metals.
... The significance of rivers to the ecological and economic development of the society cannot be overemphasized. Nevertheless, water obtained from rivers are reasonably susceptible to pollution because they are obviously exposed; simply reachable for substantial uses for agriculture, industries, and public and private practices (Li et al., 2016). Water pollution arises after a body of water is undesirably affected owing to the introduction of huge quantities of chemical constituents into the water, rendering it unhealthy for proposed use. ...
In order to assess the status of heavy metal contamination in Orashi River, water samples were collected from Orashi River bimonthly at different stations. The samples were analyzed for the concentrations of manganese (Mn), mercury (Hg), cadmium (Cd), lead (Pb), copper (Cu), nickel (Ni), iron (Fe), chromium (Cr) and zinc (Zn) ions using atomic absorption spectrophotometry (AAS). It was observed that the mean concentrations of the metal ions varied in the order: Ni >Fe > Mn > Cu > Zn > Cr > Pb > Cd > Hg. The levels of all the heavy metal ions were lower than WHO and SON standards for drinking water except Ni. There were both spatial and monthly variations in the metal ions concentrations. Calculated contamination factors indicated that the river was at various levels of contamination by the heavy metals except Ni that was observed at pollution level. Pollution index analysis showed slight level of contamination with the heavy metals. Contamination degree and modified contamination degree analysis showed very low degrees of contamination. Findings from this study portend that the Orashi River is at the threshold of contamination if pollution load to the river is not controlled.
... The watershed has suffered severe environmental deterioration due to rapid economic development coupled with lagging infrastructure to protect the environment. Research to date in the Wen-Rui Tang River watershed has primarily focused on the effects of nitrogen and phosphorus (Mei et al., 2014;Chen et al., 2016), polycyclic aromatic hydrocarbons and organic carbon (Li et al., 2016) in the hypoxic/ anoxic waterways. In addition, Gu et al. (2012) and Song et al. (2012) examined the ecological risk of sediments in the Wen-Rui Tang River network. ...
Heavy metal pollution is a major concern in China because of its serious effects on human health. To assess potential human health and ecological risks of heavy metal pollution, concentration data for seven heavy metals (As, Pb, Cd, Cr, Hg, Cu, Zn) from 14 sites spanning the rural-urban interface of the Wen-Rui Tang River watershed in southeast China were collected from 2000 to 2010. The heavy metal pollution index (HPI), hazard index (HI) and carcinogenic risk (CR) metrics were used to assess potential heavy metal risks. Further, we evaluated the uncertainty associated with the risk assessment indices using Monte Carlo analysis. Results indicated that all HPI values were lower than the critical level of 100 suggesting that heavy metal levels posed acceptable ecological risks; however, one site having an industrial point-source input reached levels of 80-97 on several occasions. Heavy metal concentrations fluctuated over time, and the decrease after 2007 is due to increased wastewater collection. The HI suggested low non-carcinogenic risk throughout the study period (HI < 1); however, nine sites showed CR values above the acceptable level of 10-4for potential cancer risk from arsenic in the early 2000s. Uncertainty analysis revealed an exposure risk for As at all sites because some CR values exceeded the 10-4level of concern; levels of Cd near an old industrial area also exceeded the Cd exposure standard (2.6% of CR values > 10-4). While most metrics for human health risk did not exceed critical values for heavy metals, there is still a potential human health risk from chronic exposure to low heavy metal concentrations due to long-term exposure and potential metal interactions. Results of this study inform water pollution remediation and management efforts designed to protect public health in polluted urban area waterways common in rapidly developing regions.
Dredging, remediation, and other management of sediment in polluted urban wetlands require the information of environmental risks associated with heavy metals (HMs). In this study, sediment samples collected from three typical wetlands in the urban area of Wenzhou City, China, were analyzed to evaluate their risks posed by five HMs. Sediments from an industrial area stored higher Cr and Cu but lower Cd and Pb than those from the residential and agricultural areas. The assessment by the pollution load index method indicated that all of the three study wetlands were polluted. An ecological risk index approach identified low risk for wetlands in forested and residential areas but high risk for wetlands in an industrial area as well as in mixed residential and agricultural area, which was also confirmed by the geo-accumulation index (Igeo) method. Furthermore, the ratio of the secondary phase and primary phase and risk assessment code methods recognized that Cd poses a high pollution risk. The results indicated that sediment pollution by HMs in urban wetlands is possibly a widespread problem in China and needs great attention.
Urban wetlands play an important role in maintaining the environmental systems of cities in southeastern China where population is large, economy is active and rainfall is plentiful.
