Ecological Risk Assessment of Arsenic and Metals in Surface Sediments from Estuarine and Coastal Areas of the Southern Bohai Sea, China

Abstract

Naturally occurring Au nanoparticles (AuNPs) have been widely observed in ore deposits, coal, soil, and environmental water. Identifying the source of these naturally occurring AuNPs could be helpful for not only the discovery of Au deposits through advanced exploration methods, but also the elucidation of the biogeochemical cycle and environmental toxicity of ionic Au and engineered AuNPs. Here, we investigated the effect of natural/simulated sunlight and heating on the reduction of ionic Au by ubiquitous dissolved organic matter (DOM) in river water. The reductive process probed by X-ray photoelectron spectroscopy revealed that phenolic, alcoholic, and aldehyde groups in DOM act as reductive sites. Long-time exposure with thermal and photoirradiation induced the further fusion and growth of AuNPs to branched Au nanostructure as precipitation. The formation processes and kinetics of AuNPs were further investigated using humic acid (HA) as the DOM model, with comprehensive characterizing methods. We have observed that HA can reduce ionic Au(III) complex (as chloride or hydroxyl complex) to elemental Au nanoparticles under sunlight or heating. In this process, nearly all of the Au(III) could be reduced to AuNPs, in which HA serves as not only the reductive agent, but also the coating agent to stabilize and disperse AuNPs. The size and stability of AuNPs were highly dependent on the concentration ratio of Au(III) to HA. These results imply that, besides biological processes, this thermal or photochemical reduction process is another possible source of naturally occurring AuNPs in natural environments, which possibly has critical impacts on the transport and transformation of Au and engineered AuNPs.

Temporal and spatial distribution of semicarbazide in western Laizhou Bay

“…During the last decade, several studies have investigated metal contaminants in surface water, sediment, as well as aquatic organisms along the north coast of the Shandong Peninsula (Liang et al, 2004;Wang et al, 2005;Xu et al, 2013;Gao et al, 2014;Li and Gao, 2014). In the present study, chemical analysis of oyster tissues was performed to identify contaminant conditions, and several physiological parameters and biomarkers indicative of oxidative stress, neurotoxicity and genotoxicity were also investigated to assess the health status of selected organisms.…”

“…1), including Yangkou (YK), Xinzhuang (XZ), Penglai (PL), Zhifudao (ZFD), Xin'an (XA), Muping (MP), and XiaoShidao (XSD). The sites were selected according to their potential environmental pressure and historical data (Wang et al, 2005;Xu et al, 2013). YK, XZ, PL, XA and MP are estuarine areas, while ZFD and XSD are traditional aquaculture areas.…”

“…The north coast of the Shandong Peninsula, located along the southern Bohai Sea, is one of the most important economic zones and industrial clusters in Northeast China. Heavy metals distribution and contamination in the surface seawater and sediment (Xu et al, 2013;Gao et al, 2014) as well as bivalve species (Liang et al, 2004;Wang et al, 2005;Li and Gao, 2014) have been documented in this region. However, there is little information about biological effects-based monitoring of such metal contamination in this region.…”

“…Bohai Sea is a nearly enclosed interior sea of northeast China (Meng et al, 2008). Previous studies have recorded that Bohai Sea and the nearby coastal areas and estuaries were suffering severe problem of metal pollution (Wang et al, 2011;Xu et al, 2013). The north coast of the Shandong Peninsula, located along the southern Bohai Sea, is one of the most important economic zones and industrial clusters in Northeast China.…”

Effects of Cu2+ and Zn2+ on growth and physiological characteristics of green algae, Cladophora

“…Such as inhibition of cell division and photosynthesis (Lage et al 2001;Perales-Vela et al 2007). Rivers contain the highest concentrations of arsenic, cadmium, copper, mercury, and zinc (Xu et al 2014), so estimating the toxic effect of Cu 2+ and Zn 2+ on the aquatic organism is important. Koutsogiannaki et al (2006) had researched cytotoxic mechanisms of Zn 2+ involving Na + /H + exchanger (NHE) activation by ROS.…”