夏季莱州湾及附近水域理化环境及营养现状评价

Evaluation of the physicochemical environment and nutrition status in Laizhou Bay and adjacent waters in summer

关键词:  莱州湾  溶解无机氮  磷酸盐  营养现状  潜在性富营养化  有机污染

Key words:  Laizhou Bay  Dissolved inorganic nitrogen  Phosphate  Nutrition status  Potential eutrophication  Organic pollution

摘要:

根据2007年8月对莱州湾及附近水域的调查资料，讨论了温度、盐度、pH、溶解氧(DO)、溶解无机氮(DIN)和活性磷酸盐(PO3-4-P)等理化因子的分布特征，并对该水域的营养水平和有机污染状况进行了评价。结果表明，莱州湾西部和西南部水域表层和底层的DIN含量较高，均呈向东北方向递减的趋势；表层PO3-4-P含量分布较为均匀，在湾口中部水域有一小范围的高值区，并呈向四周逐渐递减分布。底层水平基本与表层一致，但其高值区范围较大，等值线较为密集。营养盐与盐度的相关分析表明，DIN与盐度呈显著负相关，表明DIN主要来自河流径流的输送；而PO3-4-P与盐度相关性不十分显著，这表明莱州湾PO3-4-P的补充并非主要来自河流径流输入，而是以有机物的分解矿化再生为主，同时，浮游植物的大量繁殖也是一个重要的影响因素。由水域环境质量评价结果看，N/P值均大于Redfield比值16，P显得相对缺乏。根据营养化评价模式和有机污染指数计算结果, 2007年夏季莱州湾水域营养水平基本属于磷中等限制潜在性富营养，有机污染程度属3级，表明该调查水域受到轻度有机污染。

Abstract:

In order to study the distribution characteristic of temperature, salinity, pH, dissolved oxygen, DIN and PO3-4-P and evaluate the nutrient level and organic pollution situation in Laizhou Bay and its adjacent waters, samples were collected and analyzed in August 2007. the results showed that the concentration of inorganic nitrogen was relatively high in both surface and bottom of west and southwest waters of Laizhou Bay, which showed an decreasing trend from the west and southwest to the northeast. The PO3-4-P in surface waters was well distributed, a small high value area was found in the middle waters of Laizhou Bay, the concentration decreased from the center toward the periphery gradually. Concentrations of PO3-4-P in bottom waters were different from those in surface waters correspondingly, but the scope of high value area was greater and isoline was more intensive. According to the correlation analysis between nutrient and salinity, there was significant negative correlation between DIN and salinity, indicating that the riverine input was the main sowrce of DIN. Since there was not significant correlation betweenPO3-4-P and salinity, riverine input was not the main source of PO3-4-P； the concentration of PO3-4-P was maintained mainly by the decomposition and mineralization of organic materials. In addition, mass reproduction of phytoplankton was another important influencing factor for PO3-4-P. According to water environment evaluation result, the value of N/P ratio was higher than the Redfield ratio of 16,and phosphate was the limiting factor for the growth of phytoplankton. Based on the evaluation mode of eutrophication and organic pollution index, The nutrient level of Laizhon By was medium phosphorus limiting potential eutrophication, and the organic pollution degree remained at the third level in summer 2007, which indicated that the water area had been polluted by organic materials slightly.