Comparison of arsenic and heavy metals contamination between existing wetlands and wetlands created by river diversion in the Yellow River estuary, China

Abstract

Samples were collected at 71 sites in the Yellow River Delta Natural Reserve in December 2010 to represent soil conditions before and after the Yellow River (YR) diversion. The As, Cd, Cu, Pb, Zn, and Ni concentrations were measured to determine metal contamination levels. Results suggest that Cd concentrations were significantly higher after the YR diversion than before. The As, Cd, Cr, Cu, Ni, Pb, and Zn soil contamination indices did not exceed contamination levels, although the heavy metal content increased after the YR diversion. The mean concentrations of these heavy metals were lower than the Class I criteria. Correlation analysis shows significant correlations between As and Cr, Cu, Ni, Pb, and Zn concentrations both before and after the YR diversion. However, no significant correlations were observed between heavy metal concentration and pH before the diversion, and no heavy metal concentration was correlated with salinity. The principal component analysis indicates that these trace elements, including As, were closely correlated with each other and therefore likely originated from shared pollution sources before the diversion. These results are useful for assessing the heavy metal contamination and proposing feasible suggestions to improve soil quality.

Heavy metals pollution in soil profiles from seasonal-flooding riparian wetlands in a Chinese delta: Levels, distributions and toxic risks

“…Soils or sediments in © 2016. This manuscript version is made available under the Elsevier user license http://www.elsevier.com/open-access/userlicense/1.0/ riparian wetlands do not only act as the main precipitator for trace metals, but are also potential secondary sources of heavy metals when hydrological conditions change in these wetlands (Xie et al, 2014;Chen et al, 2016). Polluted sediments transported onto the river terrace due to flooding, contribute significant quantities of heavy metals to riparian soils (Bai et al, 2012).…”

Heavy metals in wetland soils along a wetland-forming chronosequence in the Yellow River Delta of China: Levels, sources and toxic risks

“…As a result of the complex interaction between fluvial and marine processes, coastal wetlands often act as a main sink for heavy metals bonded in the sediment and soil (Sun et al, 2015;Bai et al, 2011a;Williams et al, 1994). With the accumulation of heavy metals, coastal wetlands may gradually become a potential source of heavy metals since heavy metals can also be released from soil/sediment in the changing environment (Xie et al, 2014). Up to now, a large number of researches on heavy metals in estuarine and coastal wetlands have been conducted in larger deltas such as the Yellow River Delta (Sun et al, 2015;Bai et al, 2012) , the Yangtze River Delta (Hu et al, 2015;Hu et al, 2013;Gorenc et al, 2004) , the Pearl River Delta (Xiao et al, 2012;Zhang et al, 2010;Li et al, 2007) , the Mekong River Delta (Cenci and Martin, 2004), the Amazon River Delta (Vital and Stattegger, 2000) and the Mississippi River Delta (Grabowski et al, 2001) and so on.…”

Occurrence of red clay horizon in soil profiles of the Yellow River Delta: Implications for accumulation of heavy metals

“…Previous studies on the heavy metal pollution in soils of the YRD mainly focused on the wetland, which showed unpolluted or moderately polluted levels of heavy metals (Bai et al, 2012;Xie et al, 2014;Yao et al, 2015). These studies also showed that soil organic matter, moisture and clays were key factors to influence the distribution of heavy metals in this area.…”