Abstract
Accurate estimation of the variability of heavy metals in river water and the hyporheic zone is crucial for pollution control and environmental management. The biotoxicities and potential ecological risks of heavy metals (Cu, Zn, Pb, Cd) in a solid-liquid two-phase system were estimated using the Geo-accumulation Index, Potential Ecological Risk Assessment and Quality Standard Index methods in the Weihe River of Shaanxi Province, China. Water and sediment samples were collected from five study sites during spring, summer and winter, 2013. The dominant species in the streambed sediments were chironomids and flutter earthworm, whose bioturbation mainly ranged from 0 to 20 cm. The concentrations of heavy metals in surface water and pore water varied obviously in spring and summer. The degrees of concentration of Cu and Cd in spring and summer were higher than the U.S. water quality Criteria Maximum Concentrations. Furthermore, the biotoxicities of Pb and Zn demonstrated season-spatial variations. The concentrations of Cu, Zn, Pb and Cd in spring and winter were significantly higher than those in summer, and the pollution levels also varied obviously in different layers of the sediments. Moreover, the pollution level of Cd was the most serious, as estimated by all three assessment methods.
Highlights
The hyporheic zone is the saturated area between surface water and groundwater [1]
This study evaluated four main heavy metals for the Weihe River, including Cu, Zn, Pb and Cd, and we adjusted the classification standards of evaluation indexes [10] including Ei, ecological risk of multiple heavy metals (ERI) and the corresponding levels of ecological hazards according to types and amounts of heavy metals (Table 3)
We identified the benthos samples collected from five gauges of the Weihe River in Shaanxi Province in spring and summer, and the results showed that the chironomid larvae and tubificidae accounted for
Summary
The hyporheic zone is the saturated area between surface water and groundwater [1]. As a transitional belt between the surface water and groundwater systems [2], it plays an essential role in the water exchange process, hydrologic regulation, environmental buffer and ecological protection [3]. Heavy metals have become essential elements disturbing the normal functions of a stream due to their characteristics of serious toxicity, difficult degradation and easy concentration [6] This usually causes secondary pollution if heavy metals in sediments are discharged through a series of biological, physical and chemical processes when the sedimentary conditions are changed [7]. Many studies on heavy metals in rivers have been conducted and many great results have been published in the literature, such as spatial distributions of heavy metals in streambeds, sources and ecological assessment [10,11,12,13] These studies focused on the horizontal distribution at a surface depth between 0 cm and 10 cm and the vertical activity range of aquatic benthos was not considered. In comparison to [25], we classified the pollution levels of the heavy metals in sediments into seven levels based on the geo-accumulation index ranges (Table 2).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: International Journal of Environmental Research and Public Health
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
