Distribution characteristics and environmental significance of carbon, nitrogen and phosphorus in core sediments of Daya Bay

Biogeochemical observations were carried out to determine TOC,TN and TP contents and their distribution characteristics in sediments of the Daya Bay.The results showed that,the content of TOC,TN and TP ranged from 0.4810-2 to 1.5310-2,from 316.2410-6 to 570.4710-6,from 206.0210-6 to 342.0210-6,respectively.Both TOC and TN in sediments had an increasing trend from bottom to surface,and TP content increases with core depth.According to the ratios between TOC and TN and also their correlation,organic matter mainly came from terrene,and the vertical variation was mainly controlled by TOC content.The vertical distribution of TN,TP contents and the ratios between TOC and TN were in accordance with the increased trend of nutrient content in seawater of the Daya Bay.Low deposition rate was the main factor leading to low burial fluxes of biogenic elements.Since twenty mid-1980s,the burial fluxes of TN and TOC increased due to increased human activities.However,the efforts of controlling pollution in recent years had improved the environment of the Daya Bay.Our investigation confirms that the burial fluxes of biogenic elements can be a good proxy indicating environment changes of the Daya Bay.