钦州湾疏浚工程磷释放对海湾生态环境的影响

Impact of Phosphorus Release from Qinzhou Bay Dredging Project on Bay Ecological Environment

关键词:  钦州湾  疏浚工程  沉积物  磷释放  生态影响  营养盐  浮游植物

Key words:  Qinzhou Bay  dredging engineering  settlings  phosphorus release  ecological impact  nutrient salt  phytoplankton

摘要:

为了解近海工程疏浚对海湾生态环境的影响，2015年7月，分别在不同工期（施工期、非施工期）和潮时（高潮、低潮），对广西钦州湾疏浚工程进行共4个航次的现场跟踪监测，比较不同施工状态下疏浚工程对海湾生态环境的影响。结果显示，疏浚工程的施工扰动使水体中悬浮物、溶解无机氮（Dissolved Inorganic Nitrogen，DIN）和溶解无机磷（Dissolved Inorganic Phosphorus，DIP）浓度显著增加。疏浚工程附近站点DIN和DIP浓度比对照站点大幅增加，最大增幅分别为151.7%和580.0%，DIP增加幅度大于DIN增加幅度。疏浚活动导致沉积物营养盐释放，明显改变了局部海区营养盐浓度的分布格局。在钦州湾外湾，疏浚工程引起的内源磷元素释放强于氮元素，改变了海湾的营养盐结构特征（c_N/c_P值）及浮游植物磷胁迫/限制状态，可能引发水华或赤潮，需要加以关注。

Abstract:

In July 2015,in order to understand the impact of offshore dredging engineering on the ecological environment of the gulf,4 marine environmental investigations in Qinzhou Bay were carried out during different construction (construction periods,non-construction periods) and tide time (high tide,low tide).The impact of dredging projects on the bay ecological environment under different construction conditions was compared.The results showed that the construction disturbance of the dredging project significantly increased the concentration of suspended solids in the water body,and significantly increased the concentration of Dissolved Inorganic Nitrogen (DIN) and Dissolved Inorganic Phosphorus (DIP) in the water.The DIN concentration and DIP concentration of the station near the dredging project increased significantly compared with the control station,with the maximum increase of 151.7% and 580.0%,respectively.The increase of DIP was greater than the increase of DIN.Dredging activities resulted in the release of nutrients in sediments,which significantly changed the distribution pattern of nutrient concentration in local sea areas.In the outer bay of Qinzhou Bay,the release of endogenous phosphorus element caused by dredging project was stronger than nitrogen element,which changed the nutrient structure characteristics (c_N/c_P value) of the bay and the phosphorus stress/restriction status of phytoplankton,which might cause water bloom or red tide,which needed more attention.