2012年春秋季罗源湾表层海水水质状况及富营养化评价

Seawater quality and eutrophication assessment in surface water of Luoyuan Bay in spring and autumn of 2012

根据2012年5、10月春秋两季福建省罗源湾海水化学调查数据,对罗源湾内的4个海洋环境分级控制区的水质状况及水质控制目标实现情况进行了分析,并对该湾的营养盐含量的平面分布、季节变化、N/P比值结构进行了分析,对罗源湾水体富营养化程度进行了评价.调查结果显示,罗源湾主要污染物质为无机氮和活性磷酸盐,春秋季无机氮平均含量分别为0.363 mg/dm3和0.428mg/dm3,活性磷酸盐平均含量分别为0.039 mg/dm3和0.062 mg/dm3,含量均显著高于该湾功能区划要求.两个季节罗源湾海水水质平面分布趋势基本一致,湾口水质相对较好,向湾内水质呈逐渐恶化的趋势.罗源湾内的4个海洋环境分级控制区中,渔业环境保护利用区两个航次均未达到水质控制目标;生态廊道保护利用区5月份部分达标,而在10月份则全部未达标;北岸、南岸港口与工业开发监督区也是部分达标.虽然水质状况春季优于秋季,发生赤潮的可能性,春季却大于秋季.自20世纪80年代以来,罗源湾的水环境质量呈逐渐恶化的趋势,尤其是自21世纪以来,水质恶化趋势明显加剧.

Water qualities by the 4 marine environment graded control areas in Luoyuan Bay was studied based on the data obtained in May and October 2012.Besides,the horizontal and seasonal distribution of nutrients,ratio of N /P,and eutrophication status of seawater were assessed.The results showed that dissolved inorganic nitrogen （DIN）and active phosphors were important contaminants.The average concentration of DIN was 0.363 mg/dm3 in May and 0.428 mg/dm3 in October while that of active phosphors was 0.039 mg/dm3 and 0.062 mg/dm3 respec-tively.The water quality distributed in the same pattern in these two months and it deteriorated from the inlet into the inner bay.The water quality control objective for fishery environment protection and utilization area in Luoyuan Bay was not achieved in both May and October.In case of ecological corridor protection and utilization area in Luoyuan Bay,the water quality control objective was achieved just within the inlet in May,but unrealized within the whole bay in October.The situation was somewhat better in the north bank and the ports and industry develop-ment and supervision areas in the south bank.In these two areas,the water quality control objective was achieved in the inlet in both May and October,though it was still unrealized in the inner bay.The water quality was better in May than in October,but the probability for the outbreak of red tide was higher in October than in May.Since 1980s,the water quality in Luoyuan Bay had deteriorated gradually and it trended to worse especially after 2000.