| 摘要: |
| 北部湾近年藻华灾害频发，为了解与藻华暴发密切相关的营养盐及水质状况，2020年8月对北部湾北海半岛铁山港、营盘、涠洲岛、斜阳岛及涠洲岛西部远岸海域共21个站位采集表层海水，分析营养盐含量和结构特征，并利用富营养化指数和有机污染指数对该海域水质进行等级划分与评价。结果表明：北海半岛海域DIN、PO4-P和SiO3-Si均值分别为0.210mg/L、0.021mg/L和0.270mg/L。其中，铁山港营养盐由港内至港外呈递减趋势，营盘海域由近岸至远岸，DIN和SiO3-Si含量先递减再增加，PO4-P则表现为递增，涠洲岛海域及远岸各站位营养盐分布无明显特征。北海半岛海域N/P、Si/N和Si/P均值分别为11.8、1.7和14.6，显示47.6%海域为潜在N限制，而潜在P限制和Si限制海域均为9.5%；叶绿素a仅与COD显著相关，相关系数为0.475。调查海域富营养化指数均值1.82，以铁山港港内富营养化程度最高，由港内严重富营养至港外贫营养递减，营盘近岸7号站位中度富营养，其余76.2%调查站位仍处于贫营养水平；有机污染指数均值1.85，良好和较好水质共占38.1%，其余61.9%水质受到不同程度有机污染，亦以铁山港水质污染最为严重，重度污染仅在该海域发现。可见，北海半岛夏季表层海水以潜在N限制为主，铁山港和营盘近岸富营养化和有机污染较严重，其余站位基本良好，影响表层水体叶绿素a含量的主要因素是有机质，可能与海域微生物强烈降解作用相关。本研究可为北部湾海洋环境保护和赤潮研究提供基础环境数据。 |
| 关键词: 营养盐 水质 评价 北海 北部湾 |
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| Summer nutrients and water quality in Beihai Peninsula of Guangxi |
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Xu Yixiao1, TAO Xiaoping1, LIU Chenghui2, WEI Guangling1, HE Xilin1, LI Bin2
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1.Nanning Normal University;2.Guangxi Mangrove Research Center
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| Abstract: |
| Algal blooms occur frequently in Beibu Gulf in recent years. In order to understand the nutrients and water quality conditions closely related to algal blooms, surface seawater was collected from 21 stations in Tieshan Bay, Yingpan, Weizhou Island, Xieyang Island and the far west coast of Weizhou Island in Beihai Peninsula of Beibu Gulf in August 2020. The nutrients and water quality were analyzed, then evaluated by using eutrophication index and organic pollution index. Results show that the average contents of DIN, PO4-P and SiO3-Si in Beihai Peninsula were 0.210 mg/L, 0.021 mg/L and 0.270 mg/L, respectively. Among them, the nutrients in Tieshan Bay showed a decreasing trend from inside to outside, and nutrients of DIN and SiO3-Si in Yingpan decreased first and then increased, while PO4-P showed an increasing trend from inshore to offshore. But no nutrients distribution pattern was observed near Weizhou Island and at other offshore stations. The average values of N/P, Si/N and Si/P in Beihai Peninsula were 11.8, 1.7 and 14.6, respectively, exhibiting 47.6% of the sea areas with potential N limitation, and each 9.5% with potential P limitation and Si limitation. Chlorophyll a was only significantly correlated with COD, and the correlation coefficient was 0.475. The average eutrophication index of Beihai Peninsula is 1.82, and the eutrophication in Tieshan Bay is the most serious, from severe eutrophication inside the port to oligotrophic status outside the port of Tieshan Bay. Station 7 located at Yingpan inshore was moderately eutrophication, whereas the rest 76.2% of Beihai Peninsula exhibited oligotrophic status. The average organic pollution index for Beihai Peninsula was 1.85, with good water quality accounting for 38.1%, and the rest of 61.9% was polluted by organic pollution to some extent. Tieshan Bay was the most serious water pollution area, and heavy pollution was only found in this area. Generally, the main surface water of Beihai Peninsula is potential N limitation in summer, the eutrophication and organic pollution in Tieshan Bay and Yingpan are much worse than in the rest stations. The major factor affecting the chlorophyll a content in surface water is organic matter, which may be related to the strong degradation of marine microorganisms. This study will provide basic data for marine environmental protection and harmful algal blooms management in Beibu Gulf. |
| Key words: Nutrients water quality assessment Beihai Beibu Gulf |