山东半岛南部近岸海域富营养化状况的多元评价研究

于2006年至2007年分四个季度月对山东半岛南部近岸海域(35.5°~36.7°N,119.8°~121.3°E)的营养盐和叶绿素a进行了设站调查,分析了该海域上述因子时空分布特征,同时应用主成分分析(PCA)和潜在富营养化评价方法对该海域的富营养化状况进行了分析,初步确定了影响该海域富营养化状况的主要驱动因子。结果表明:(1)在时间分布上,总氮、总磷、活性磷酸盐、溶解态氮与总无机氮和活性硅酸盐的季节变化类似,均表现出秋冬季浓度较高而春夏季较低的趋势,而总磷、溶解态磷的浓度则在冬季最高,在夏秋季较低,叶绿素a浓度的季节变化趋势为春夏季较高,而冬季最低;该海域营养盐与叶绿素a浓度空间分布以胶州湾和丁字湾为中心,总体呈现出由近岸向离岸海域逐渐递减的趋势;(2)应用主成分分析对调查结果进行分析,结果显示10项调查指标(营养盐与叶绿素a)可以转换提取4个主成分,解释82.00%的结果。主成分综合得分可以作为富营养化程度的评价指标,据此得到调查海域富营养化状况的季节变化趋势由高到低依次为秋季、冬季、春季、夏季,总体呈现出以胶州湾和丁字湾为中心,沿岸及北部海域富营养化程度较高的格局;分析结果还表明总无机氮是该海区富营养化形成的主要驱动因子;(3)利用潜在富营养化评价方法对调查海域富营养化状况进行了初步分析,结果表明该海区仅于秋季表现为总体中度营养,在其他季节总体趋势均为贫营养,胶州湾与丁字湾附近海域在春秋季表现为磷限制潜在富营养化。主成分分析法较潜在富营养化评价方法更敏感,不仅能够定量表述海区富营养化状况,而且能够有效确定富营养化驱动因子。

A multivariate assessment of eutrophication in the coastal waters of the southern Shandong Peninsula

The spatial-temporal distribution and variations of nutrients and chlorophyll a (Chl a) in the coastal waters(35.5°~36.7°N, 119.8°~121.3°E) of the southern Shandong Peninsula were studied based on four cruises during 2006-2007. Both principal component analysis (PCA) and potential eutrophication assessment were carried out to assess the eutrophication status of the investigated area, and the potential eutrophication driving factors were evaluated. Results showed that (1) seasonal variations of total nitrogen (TN) and active phosphate were similar to those of dissolved inorganic nitrogen (DIN) and active silicate with concentrations higher in autumn and winter, while concentrations of total phosphate (TP) and dissolved phosphate (DOP) were higher in winter and lower in summer and autumn. The concentration of Chl a was higher in spring and summer and lower in winter. Horizontal distributions of nutrients and Chl a centered at the Jiaozhou Bay and the Dingzi Bay with concentrations higher in shore than offshore; (2) PCA were applied to estimate the eutrophication status and four PCs were extracted from ten variables, which explained 82.00% of the total information in the original data set. The distribution of integrated score, which was considered to be an indicator for eutrophication, indicated that eutrophication was more serious in the Jiaozhou Bay and the Dingzi Bay, and the northern area showed more serious situation than southern area. Further result demonstrated that DIN was the strongest driving factor for eutrophication in the region; (3) potential eutrophication assessment was also applied to evaluating the eutrophication status of the area and the result showed that in autumn, the investigated area can be classified as moderate-level nutrient area, and the Jiaozhou Bay and the Dingzi Bay can be characterized by phosphate-limiting moderate-level nutrient in spring. PCA, which can be considered as a more sensitive method for eutrophication estimation compared with potential eutrophication assessment, it not only quantitatively reflects eutrophication state, but also determines the driving factors for eutrophication in the region.