夏季珠江口叶绿素a和营养盐分布特征及其与环境因子的关系

本研究基于2019年夏季珠江口附近海域的现场调查数据，分析了珠江口叶绿素a（chlorophyll a，Chl a）和营养盐的分布特征，并结合环境因子进行了探讨。结果表明:夏季珠江口海域表层Chl a和溶解氧（dissolved oxygen，DO）浓度分别为4.192～88.209 μg/L和4.610～10.586 mg/L；溶解无机氮（dissolved inorganic nitrogen，DIN）、活性磷酸盐（PO₄-P）和活性硅酸盐（SiO₃-Si）浓度分别为0.168～1.247 mg/L、0.011～0.044 mg/L和0.694～6.916 mg/L。夏季珠江口浮游植物生长旺盛，依据美国河口营养状况评价（NEEA-ASSETS）标准，44.4%的站位处于高度富营养化（20 μg/L60 μg/L）。珠江径流量是夏季珠江口浮游植物空间分布的主要驱动因素，珠江口口门内浮游植物生长受光限制和径流稀释影响并未出现高值，珠江口口门外浮游植物旺发消耗了大量磷酸盐，磷成为浮游植物生长的限制因子。Chl a与盐度、PO₄-P呈显著负相关性，与DIN、DIN/P呈显著正相关性，表明河口冲淡水对浮游植物生长影响显著。

Distribution characteristics of chlorophyll a and nutrients in the Pearl River Estuary in summer and their relationship with environmental factors

Based on the field survey data near the Pearl River Estuary (PRE) in the summer of 2019, the distribution characteristics of chlorophyll a (Chl a) and nutrients in the PRE were analyzed, combined with environmental factors. The results show that Chl a and dissolved oxygen (DO) at the surface in summer are 4.192～88.209 μg/L and 4.610～10.586 mg/L in the PRE, respectively; The concentrations of dissolved inorganic nitrogen (DIN) and active phosphate (PO₄-P) and active silicate (SiO₃-Si) were 0.168～1.247 mg/L, 0.011～0.044 mg/L and 0.694～6.916 mg/L, respectively. Phytoplankton grows vigorous in the PRE in summer. According to the NEEA-ASSETS standard, 44.4% of all the stations belong to highly eutrophication (20 μg/L60 μg/L) . Runoff is the main driving factor of the spatial phytoplankton distribution in the PRE in summer. Since the growth of phytoplankton in the inner area of the PRE is affected by light limitation and runoff dilution to some degree, there is no high Chl a values in the area. Consumption of phosphate by plenty of phytoplankton in the outer area of the PRE, making phosphate become a limiting factor of phytoplankton growth. Chl a was significantly negatively correlated with salinity and PO₄-P, and was significantly positively correlated with DIN and DIN/P, suggesting that the estuary diluted water exerted a significant impact on the growth of phytoplankton.