胶州湾微表层和次表层海水中营养盐的分布特征及富营养化研究

根据2010年夏季(6、7、8月)和秋季(9、10、11月)6个航次对胶州湾微表层和次表层海水中营养盐的调查结果,研究了微表层和次表层中营养盐的分布特征和时空变化,以及微表层对氮、磷、硅营养盐的富集情况,并利用潜在富营养化评价模式评价了水质的营养状况.结果表明,不论是微表层还是次表层,营养盐的分布都是从湾内向湾口递减.胶州湾夏季微表层溶解无机氮(DIN)、磷酸盐(PO34--P)和硅酸盐(SiO23--Si)的平均浓度分别为0.296、0.026和0.618mg.L-1;秋季平均浓度分别为0.369、0.028和0.592mg.L-1.夏季次表层DIN、PO43--P和SiO23--Si的平均浓度分别为0.240、0.025和0.506mg.L-1;秋季平均浓度分别为0.292、0.028和0.580mg.L-1.胶州湾微表层海水对营养盐N、Si均有不同程度的富集作用,平均富集因子为1.48～1.96;对P无富集现象,富集因子的不同可能与海况和站位的不同有关.在所有调查航次中,7月份胶州湾海水中的营养盐含量最低,与叶绿素a(Chl-a)处于高峰期有关.胶州湾东北部处于富营养和磷中等限制潜在性富营养化状态,其它区域营养级为中度营养和贫营养,微表层潜在性富营养化程度大于次表层.

Nutrients distributional characteristics and eutrophication in the sea-surface microlayer and subsurface water in the Jiaozhou Bay

Based on observed nutrient data collected in the sea-surface microlayer (SML) and subsurface water of Jiaozhou Bay during 6 cruises in summer (June, July and August) and autumn (September, October and November) of 2010, the distributional characteristics and spatio-temporal variations of nutrients and the enrichment extents of N, P, Si in the sea-surface microlayer were studied and the water quality status was assessed by using the assessment model of potential eutrophication. Results showed that in the sea-surface microlayer and subsurface water, the concentrations of nutrients decreased gradually from the inner bay to the bay mouth. The mean concentrations of dissolved inorganic nitrogen (DIN), phosphate and silicate in the sea-surface microlayer of Jiaozhou Bay in summer were 0.296, 0.026 and 0.618 mg·L^-1, respectively, and those in autumn were 0.369, 0.028 and 0.592 mg·L^-1. In contrast, the mean concentrations of DIN, phosphate and silicate in the subsurface water in summer were 0.240, 0.025 and 0.506 mg·L^-1, respectively, and those in autumn were 0.292, 0.028 and 0.580 mg·L^-1. The sea-surface microlayer displayed an obvious enrichment for N and Si nutrients in different degrees, with the mean enrichment factors ranging from 1.48 to 1.96 dependent on sea surface conditions and seasons. No enrichment was observed for phosphate. In the whole cruises, the contents of nutrients in Jiaozhou Bay in July were the lowest, which might be attributed to the peak of Chl-a concentration. Water eutrophication and moderate-phosphorus-limitied potential eutrophication appeared in the northeast area and moderate nutrition or oligotrophy was observed in the other areas. In addition, the potential eutrophication level in the sea-surface microlayer was higher than that in the subsurface water.