Pollution status of the Bohai Sea: An overview of the environmental quality assessment related trace metals

Abstract

It is well recognized that the ecosystem of the Bohai Sea is being rapidly degraded and the Sea has basically lost its function as a fishing ground. Billions of funds have been spent in slowing down, halting and finally reversing the environmental deterioration of the Bohai Sea. Although trace metals are routinely monitored, the data with high temporal resolution for a clear understanding of biogeochemical processes in the ecosystem of the Bohai Sea are insufficient, especially in the western literature. In this review, status of trace metal contamination in the Bohai Sea is assessed based on a comprehensive review of their concentrations recorded in the waters, sediments and organisms over the past decades. Studies show that metal contamination in the Bohai Sea is closely associated with the fast economic growth in the past decades. Concentrations of trace metals are high in coastal areas especially in the estuaries. Alarmingly high metal concentrations are observed in the waters, sediments and organisms from the western Bohai Bay and the northern Liaodong Bay, especially the coasts near Huludao in the northernmost area of the Bohai Sea, which is being polluted by industrial sewage from the surrounding areas. The knowledge of the speciation and fractionation of trace metals and the influence of submarine groundwater discharge on the biogeochemistry of trace metals in the Bohai Sea is far from enough and related work needs to be done urgently to get a better understanding of the influence of trace metals on the ecosystem of the Bohai Sea. A clear understanding of the trace metal pollution status of the Bohai Sea could not be achieved presently for lack of systematic cooperation in different research fields. It is quite necessary to apply the environmental and ecological modeling to the investigation of trace metals in the Bohai Sea and then provide foundations for the protection of the environment and ecosystem of the Bohai Sea.

Assessment of heavy metal impact on sediment quality of the Xiaoqinghe estuary in the coastal Laizhou Bay, Bohai Sea: Inconsistency between two commonly used criteria

“…Site XQH4 was also influenced by intense human activities. Exhausted gas emitted by vehicles could lead to the increase in contents of heavy metals in the environments surrounding the roads with heavy traffic; the studied metals might also be from point sources such as domestic sewage and factory wastewater discharge (Gao et al, 2014). Due to the weakening of the intensity of human activities that discharge heavy metals, total heavy metal concentrations in sediments gradually decreased from the riverine region to the marine region with the decrease of the amount of heavy metal input.…”

“…Due to the discharge of industrial effluents, agriculture wastewater and sewage runoff, concentrations of heavy metals in aquatic ecosystems have increased considerably (Prica et al, 2008;Yang et al, 2012;Gao et al, 2014). Sediment is not only an important reservoir of heavy metals in aquatic ecosystems, but also is an important source of heavy metals for the overlying water (van Den Berg et al, 1999;Wilson and Chang, 2000;Prica et al, 2008).…”

Characteristics of phosphorus components in the sediments of main rivers into the Bohai Sea

“…Ring-Bohai Region is one of China's economic hot spots, especially in the 21 st century, after the Yangtze River delta and the Pearl River delta economic zone showed vitality and the Ring-Bohai Region is becoming the third growth pole of China's economic development. Due to its special location, the industries and cities are intensive there, and it faces serious environmental problems (Gao et al, 2013). As upstream of Ziya River, a great amount of nitrogen (N) and phosphorus (P) enter into the Fuyang River and their tributaries as the wastewater and sewage input, and the phenomenon was also found in Beiyun River (Li et al, , 2012Jin et al, 2016).…”

Regime shifts and resilience in China’s coastal ecosystems

“…For instance, marine pollution has doubled since 2009 and the polluted coastal waters now cover an area of 145 000 km 2 , stretching from Vietnam to Korea (Grumbine and Xu 2013). Large projects aimed at restoring the marine ecosystem have failed or not achieved as much success as expected (Gao et al 2014). Policy and management strategies based on linear approaches that ignore dynamic interactions normally generate insufficient actions and inevitably lead to more unwanted problems.…”