Bohai Sea

Zhao, X., Zheng, M.H., Liang, L., Zhang, Q., Wang, Y., Jiang, G., 2005. Assessment of PCBs and PCDD/Fs along the Chinese Bohai Sea coastline using mollusks as bioin-dicators. Arch. Environ. Contam. Toxicol. 49, 178-185. 

Huang W. W., Martin 1. M., Seyler, Zhang J., and Zhong X. M. (1988) Distribution and behavior of arsenic in the Huanghe (Yellow river) estuary and Bohai Sea. Mar. Chem. 25, 75-91. 

The Yellow Sea is a typical epicontinental sea surrounded by the continent of China and the Korean peninsula and connected with the East China Sea to the south and with Bohai Sea in the north (Figure 12). 

Figure 12. Bathymetry and geographic system including the east China Sea, the Yellow Sea and Bohai Sea sy.stem.

Nitrogen mass balance in Yellow-Bohai Sea system... 

In accordance with approaches shown in Table 11, the total riverine N fluxes were assessed for the Yellow-Bohai sea system (UNESCO, 1978 Zhu, 1997 ESCAP, 1998 Choi, 1998 Cha et al, 1998). These data are shown in Table 19. 

Table 19. Assessment (contiued). of total nitrogen riverine fluxes to Yellow-Bohai seas system...

Table 20. Sub-regional fluxes of nitrogen in Yel-low-Bohai seas system.

In terms of pollution, only 18.7% of China s coastal waters met Grade I water quality of the Pearl River Estuary. Of China s four major sea areas, the East China was the most polluted, followed by the Bohai Sea, the Yellow Sea and the South China Sea (State of the Environment, China, 1997). 

In the northern area (the Bohai Sea and the Yellow Sea), the seasonal variations of sea surface temperature (SST) are large and vary from 0 to 28 °C. In the East China Sea, the SST averages about 21 °C and ranges from 7 to 28 °C. In the southern area (north of the South China Sea), the... 

The Bohai Sea is one of the main China marginal seas, which has its own particular state and hydrography characteristics. This includes the topography, chemical environment, hydrography, sediment pattern, riverine input, and biological characteristics. 

The Bohai Sea is a semi-enclosed continental shelf sea of the NW Pacific Ocean in northern China, located between 37°07 N to 41° N and 117°35 E to 121°10 E, with a surface area of 77x10 m , an average depth of 18.7 m and a coastline of nearly 3,800 km. The size of the Bohai Sea is about 500 km from north to south and 300 km from east to west. The Bohai Sea is a... 

Fig. 1.6. Bathymetry of the Bohai Sea (Siindermanna and Feng, 2004) (With permission from Elsevier s Copyright Clearance Center)...

The Bohai Sea is surrounded by land to the north, west and south and is connected only to the Yellow Sea through the narrow Bohai Strait, approximately 90 km wide. Rivers empty into the Bohai Sea including the Huanghe River, Haihe River, Liaohe River, and Luanhe River. 

The water temperature of the Bohai Sea is vertically homogeneous from November to March. A thermocline is gradually formed from April to May in the deep area of the Bohai Sea. The thermo-stratification intensifies and becomes greater than 1 °C/m from June to August. Then it decreases rapidly in September. The average annual precipitation in the Bohai Sea is about 500 600 mm (Feng et al., 1999). 

Conductivity-temperature-depth (CTD) data in the Bohai Sea show three low-temperature centers in summer in the middle and lower layers the central Bohai Straits, Liaodong Bay Mouth, and Bohai Bay Mouth. In addition, there is an evenly high-temperature center in the middle Bohai Sea. In winter the isotherms extend northwestward in the Bohai Sea with a cold tongue-shaped mass off Qinhuangdao towards the southeast, presenting a saddle-like isotherm pattern in the central Bohai Sea. 

Fig. 1.7. Salinity and temperature of sea bottom waters in (a) winter and (b) summer in the Bohai Sea. Solid and dotted lines denote salinity (%o) and temperature C C), respectively (Bao et al., 2004) (With permission from Bao XW)...

Long-term variations of temperatm-e and salinity in the Bohai Sea are displayed in Fig. 1.8 (Lin et al., 2001). The annual mean SSS and SST of the Bohai Sea both show ascending trends dming 1960 1997. The linear trends were 0.074%o per year for SSS and 0.011 °C per year for SST respectively. The long-term variations of these annual means both showed climate-jump years or inflection years. 

Fig. 1.8. Long-term variation of annual mean (a) SSS and (b) SST of the Bohai Sea. The solid lines are from the averages of the respective annual means of the Bohai Sea and the dashed hnes axe their linear regressions (Lin et al., 2001) (With permission from Elsevier s Copyright Clearance Center)...

In the Bohai Sea, five water masses are recognized. They are the Bohai Sea and the Yellow Sea mixed water, the North Yellow Sea bottom cold water, the Bohai Sea central water, the Bohai Sea coastal water and the continental diluted water. There is a strong seasonal signal in temperature with a smaller... 

The sediments in the Bohai Sea are generally fine (Fig. 1.12, Jiang et al., 2004). They consist of soft clay mud (sediment with sizes smaller than 0.01 mm amounts to a portion of more than 70%), fine silt mud (sediment with sizes smaller than 0.01 mm amounts to a portion of 50% 70%), coarse silt, and fine sand. In Liaodong Bay the coarse silt (0.1 0.05 mm) and fine sand (0.25 0.1 mm) dominate in the sediment. In Laizhou Bay the sediment consists of silt deposits, whereas in the central basin fine sand spreads widely. At the Laotieshan waterway (entrance to the Bohai Sea), the tidal flow is very strong, the area is often eroded and therefore the sediment particles are coarse there. The constituents of SPM in the Bohai Sea are mainly inorganic... 

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