三沙湾盐田港养殖海域沉积物中的有机碳、氮和磷

The content of carbon, nitrogen and phosphorus in the surface sediment at the mariculture area in the enclosed Sansha Bay

于2012年8月（夏季）、11月（秋季）和2013年2月（冬季）、5月（春季）共4个航次对三沙湾盐田港养殖海域表层沉积物组成成分及其变化趋势进行调查分析,并采用单因子污染指数（Pi）对沉积物质量进行评价。结果表明不同功能区沉积物中有机氮（TN）、总磷（TP）和有机碳（OC）含量差异显著（P〈0.05）,TN和TP含量4季变化范围分别是0.15-1.39 g/kg和0.11-1.08 g/kg,平均值分别为（0.89±0.36）g/kg和（0.56±0.26）g/kg。OC含量在1.00-14.71 g/kg之间,平均值为（8.26±3.78）g/kg。各站位沉积物中TN污染指数4季变化范围为0.25-2.53,4季超标率分别为67%、81%、80%和90%;各站位TP污染指数4季变化范围为0.18-2.63,4个季节超标率分别为35%、80%、40%和51%;各季节OC含量均未超标;OC/N原子比全年变化范围在8.4-10.3之间,平均值为8.9±0.6。较弱的水流交换条件和海水养殖,特别是海水网箱养殖,是造成沉积物污染的主要原因,开展多营养层次的综合养殖模式是促进盐田港海水养殖可持续发展的有效途径。

An investigation has been carried out into the environmental quality of sediment in the enclosed Yantian bay, located inside the Sansha Bay, from August 2012 to July 2013. Testing was carried out at ten sampling sites, which were evenly distributed in different mariculture functional areas, during four different research trips. The single factor contaminant index （Pi） methodology was used to evaluate the environmental quality of sediment. The results showed that the concentration of total nitrogen （TN）, total phosphorus （TP） and organic carbon （OC） varied significantly between different seasons （P〈0.05）. The concentration of TN ranged from 0.15 to 1.39 g/Kg and the concentration of TP ranged between 0.11 to 1.08 g/Kg. The concentration of OC was in the range of 1.00 to 14.71 g/Kg with an average value of （8.26±3.78） g/Kg, and was found to be the highest in the oyster aquaculture area. The OC concentration in the macro-algae aquaculture area was lower than in the fish cage area, but higher than that in the control area. The Pi of TN was 1.23, 1.84, 1.56 and 1.67 in spring, summer, autumn and winter, respectively. The concentration of TN in the sediment exceeded the first class standard for marine sediment quality for fisheries in China by 67 %, 81%, 80 % and 90 % in every season. The Piof TP ranged from 0.18 to 2.63 during the period of study. Based on the Pi result, the concentration of TP exceeded the first class standard for marine sediment quality for fisheries in China by 35 %, 80 %, 40 % and 51% in spring, summer, autumn and winter, respectively. For all four seasons, the concentration of OC was lower than the China. The results detailed in this study indicate that first class standard for marine sediment quality for fisheries in the poor hydrological exchange and mariculture, especially the cage fish farming, have heavily polluted the sediment environment in the Yantian bay. The spatiotemporal change of TN, TP and OC appeared to be related to the mariculture mode. Macro-algae showed high bioextraction efficiencies with nutrients and were able to balance the nutrient produced by marine aquatic animal farming in an Integrated Multi-trophic Aquaculture （IMTA） system.