曹妃甸近海营养盐和叶绿素a的时空分布及其影响因素研究

本文通过2014年5月、2013年8月在曹妃甸周边海域分别实施春季、夏季航次，分析了营养盐和叶绿素a（Chl a）的时空分布特征、影响因素及其与温度、盐度、化学耗氧量（COD）、悬浮颗粒物（SPM）的关系，评估了水体营养状态和营养盐限制状况，并且结合历史资料探讨了围填海前后营养状况的变化情况。结果表明:调查海域无机氮（DIN）、磷酸盐（DIP）和硅酸盐（DSi）受到河流输入和沉积物释放作用的显著影响，其高值区主要出现在曹妃甸两侧的近岸海域；营养状态质量指数（NQI）在1.07~2.23之间，处于贫营养或中营养状态；营养盐限制状况具有季节差异，春季主要为Si限制，夏季主要为P限制；Chl a在春季的高值区主要分布在东侧远岸海域和东北侧内湾海域，与盐度、P和Si密切相关，其夏季高值区出现在甸头和内湾附近海域，与P和Si关系紧密。结合历史资料的比较表明春季DIN、NQI和Chl a在西侧海域有所降低，在东侧海域有所升高，这是由于围填海后潮流变化的空间差异造成了营养盐的重新分布，而夏季各断面多为DIN和NQI降低而Chl a升高，表明营养盐被浮游植物充分利用，需要结合浮游植物群落进一步分析围填海的影响。

Spatial and temporal distribution of nutrients and chlorophyll a, and their influential factors in Caofeidian coastal waters

Based on two cruises respectively carried out in May 2014 and August 2013 in Caofeidian coastal waters, temporal and spatial distributions of nutrients and chlorophyll a (Chl a), their influential factors and correlations with water temperature, salinity, chemical oxygen demand (COD) and suspended particle matter (SPM) were analyzed in this study.Trophic status and nutrient limitation were assessed, and changes of trophic status after land reclamation were discussed.The results showed dissolved inorganic nitrogen (DIN), dissolved inorganic phosphate (DIP) and dissolved silicate (DSi) were mainly affected by riverine inputs and sediment release with high values ordinarily occurred in inshore waters.Nutrient quality index (NQI) ranged from 1.07 to 2.23, indicating their oligotrophic or mesotrophic status.Nutrient limitations showed seasonal variations, which were Si limitation in spring and P limitation in summer.The high values of Chl a in spring were observed in eastern offshore waters and the northeastern bay, which was related to salinity, P and Si, while those in summer occurred near Caofeidian foreland and the northeastern bay, which was mainly related to P and Si.The comparison between historical data and this study revealed that in spring DIN, NQI and Chl a decreased in western sea areas and increased in eastern sea areas, which was possibly related to nutrients redistribution induced by spatial variations of tidal changes after reclamation, while in summer DIN and NQI decreased and Chl a increased in most study areas, suggesting nutrients were largely consumed by phytoplankton and influence of reclamation should be further discussed basing on phytoplankton community.