大鹏湾表层沉积物中碳、氮、磷的多年调查结果和有机质来源分析

依据1998—2006年18个航次13个站的调查资料,简要描述和分析了大鹏湾表层沉积物中包括碳、氮、磷的多项生物地球化学要素多年的平均空间分布和年际变化,并依据TOC/TN原子比探讨沉积物中有机质的来源.结果表明,大鹏湾的水动力条件对沉积物中各生物地球化学要素的分布变化影响不大,TOC、TN和TP含量分别为(17600±4600) mg·kg^-1、(1738±446) mg·kg^-1和(562±89) mg·kg^-1,比珠江口和大亚湾高.9年调查期间,TOC、TC、TN和TP含量的年际变化趋势都是上升的,表明随着周边地区经济的迅速发展和人口的不断增加,产生的大量有机质通过小河流和地表径流排放入海,使大鹏湾中沉积物的环境逐渐恶化.TOC/TN原子比为12.4±2.5,介于海洋浮游生物源和陆生高等植物源之间,反映了大鹏湾表层沉积物中有机质是陆源和水生2种来源的混合输入.TOC/TN原子比呈逐年上升趋势,表明大鹏湾接受陆源有机质与水生有机质的比例逐渐增加.

Multi-year measurements of carbon, nitrogen and phosphorus and sources of organic matter in the surface sediments of the Mirs Bay

Based on the data obtained at 13 sites from 18 cruises of investigation from 1998 to 2006, the multi-year averaged spatial distributions and interannual variations of biogeochemical parameters, including carbon, nitrogen and phosphorus, in the surface sediments of the Mirs Bay were analyzed. The sources of organic matters in the sediments were identified on the basis of TOC/TN atomic ratios. It was shown that the hydrodynamics in the Mirs Bay only posed a weak impact on the distributions and variations of the biogeochemical parameters in the sediments. The concentrations of TOC, total nitrogen and total phosphorus were (17600±4600) mg·kg^-1, (1738±446) mg·kg^-1 and (562±89) mg·kg^-1, respectively, which were higher than those in both the Pearl River Estuary and the Daya Bay. During the 9 years in investigation, the interannual variations of the concentrations of TOC, total carbon, total nitrogen and total phosphorus in the surface sediments witnessed an increasing trend, indicating a deterioration of the sediment environment in the bay as the rapid economic development and the continuous population increase in the peripheral areas that had brought in a mass of organic matters to the bay through many small rivers and surface runoffs. The TOC/TN atomic ratio was 12.4±2.5, in the range between those from marine planktons and land plants, suggesting that the organic matters in the sediments were a mixture from both sources of the terrestrial and the aquatic. The TOC/TN atomic ratio had undergone a trend of increase in the studied periods, showing a gradual increase of the terrestrial organic matters, relative to those from the aquatic sources, received by the bay.