Biogeochemical Cycling of Chemicals

Division of Environmental Health Risk Management, School of Geography, Earth Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK 

Some chemical compounds are degradable in the environment. For example, methane (an important greenhouse gas) is oxidized via carbon 

The transfer of an element between different environmental compartments, involving both chemical and biological processes, is termed biogeochemical cycling. The biogeochemical cycles of the elements lead and nitrogen will be discussed later in this chapter. 

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Abstract In this chapter, the biogeochemical processes in the South China Sea are described. The Zhujiang River (Pearl River) plays an important part in the biogeochemical cycling of chemical components in the northern South China Sea. The biogenic element characteristics in the Nansha coral ecosystem are intensively concerned. 

The natural biogeochemical cycles of the elements are heavily affected by the presence of anthropogenic species, which can undergo with the native ones different chemical and physical reactions as a function of the experimental conditions of pH, pE, temperature, sunlight, etc. The possible interactions are very complex, and mathematical models have been developed to help the study [1,2]. 

Photoreactions are often complex reactions that not only control the fate of many chemicals in air and water, but often produce products with chemical, physical, and biological properties quite different from those of their parent compounds more water soluble, less volatile, and less likely to be taken up by biota. Photooxidation removes many potentially harmful chemicals from the environment, although occasionally more toxic products form in oil slicks and from pesticides (Larson et al., 1977). Biogeochemical cycling of organic sulfur compounds in marine systems involves photooxidation on a grand scale in surface waters, as well as in the troposphere (Brimblecombe and Shooter, 1986). 

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