旧镇湾海水中营养盐分布与富营养化的研究

Study on Nutrient Distributions and Eutrophication in Seawater of Jiuzhen Bay,Fujian

根据2007年3月到2008年1月旧镇湾海域11个航次海水营养盐等的调查资料,分析了该海域生态环境中DIN和DIP的分布特征和时空变化,评价了水质富营养化状况。结果表明,旧镇湾DIN平均含量为0.283mg/L,以NO3-N为主要存在形式,占DIN的77.7%。旧镇湾DIP平均含量为0.023mg/L。旧镇湾海水5、7月份N/P比远远高于16,表明旧镇湾海水中磷相对于氮是匮乏的。8月份为最低,仅为4.84,其他月份N/P比平均值为11.98,略低于16,说明旧镇湾海水中氮相对供应不足。DIN和DIP变化趋势为旧镇湾内向湾外逐渐递减,与盐度分布呈负相关性。与历史资料相比,旧镇湾水质有明显改善,但仍具富营养化趋势。从春季到冬季,旧镇湾富营养化面积逐渐增加,秋季富营养化程度远高于其他季节,富营养化程度从湾内向湾外逐渐降低。

Base on the data of 11 voyages in Jiuzhen Bay from March 2007 to January 2008, we analyse the distribution character and spatial -temporal variation of dissolved inorganic nitrogen （DIN） and dissolved inorganic phosphorus （DIP） in Jiuzhen Bay and the situation of eutrophication is also assessed in this paper. Results show that NO3 - N is the main component of DIN, which has the mean concentration of 0. 283 mg/L, accounting for 77.7% of the DIN. Also, the mean concentration of DIP is 0. 023 mg/L. In May and July, the ratio of DIN to DIP （N/P ratio） in the surface seawater is far higher than 16, indicating that DIP in the area is deficient relative to DIN. The ratio shows the lowest value of 4.84 in August and in other months the mean level is 11.98, slightly lower than 16, illustrating the deficient supply of DIN. DIN and DIP have a negative correlation with the salinity distribution and decrease from inner bay towards the outside bay gradually. Though it still has the trend of eutrophication, comparing to historical data, water quality of Jiuzhen Bay has improved distinctly. The area of eutrophication gradually increases from spring to winter, however, the degree of eutrophication in autumn is much higher than other seasons and it decrease gradually from inner to outside of the Jiuzhen Bay.