The integrated methodology for the assessment of estuarine trophic status(ASSETS),which was extended and refined from the United States National Estuarine Eutrophication Assessment(NEEA),is a multi-parameter assessment system and has been widely used in eutrophication assessment in estuarine and coastal waters.The ASSETS was applied to evaluate the trophic status of the Changjiang(Yangtze)River estuary,one of the largest estuaries in the world.The following main results were obtained:(i)The estuarine export potential is"moderate susceptibility"due to the"moderate"dilution potential and"moderate"flushing potential;(ii)The overall human influence(OHI)index classified the impact of nutrients in the system as"high"due to the high level of nutrient discharge by the river which channels anthropogenic impacts in the catchments to the estuarine system;(iii)The overall eutrophic condition(OEC)in the estuary was classified into the"high"category due to frequent occurrence of nuisance and toxic algal blooms in the mixing and seawater zones;(iv)Since the nutrient loadings(e.g.,DIN)in the river is expected to continue to increase in the near future following the population increase and rapid economic growth throughout the drainage basin,the nutrient-related symptoms in the estuary are likely to substantially worsen,which leads to the"worsen high"category for the definition of future outlook(DFO).The combinations of the three components(i.e.,OHI,OEC,and DFO)lead to an overall grade as"bad"for the trophic status in the Changjiang River estuary.
2003年5月将Karl and Tien(1992)提出的Mg(OH)2共沉淀方法应用于东海赤潮高发区水体中磷酸盐的调查。本实验条件下方法的检测限为0.004μmol/L。将该方法与传统的磷钼兰方法进行对比,常规磷钼兰法高于共沉淀法。说明水体中可能存在大量酸性条件下不稳定的磷化合物,且其不能被Mg(OH)2共沉淀,如1-磷酸核糖。此时,共沉淀法的测定值更接近水体中真实的正磷酸盐含量。共沉淀法可为赤潮爆发过程中低磷阶段的样品分析提供较可靠数据。用共沉淀法提供的测定数据分析赤潮爆发过程中水体中磷酸盐的变化,长江口磷酸盐总的分布趋势是沿岸含量较高,向外海逐渐递减。赤潮爆发过程中,随着赤潮藻类增殖,水体中磷酸盐被大量消耗,表层磷酸盐浓度迅速降低;赤潮消亡阶段,表层水体磷酸盐浓度逐渐回升,而底层由于藻类死亡后逐渐沉降磷酸盐浓度升高。
This paper presents the effects of harmful algae on fish based on the studies in recent years. The results show that the harmful algae can affect the survival, enzyme, cell, tissue and behavior of fish directly or indirectly, also the phycotoxin can be accumulated in the tissue and organ of fish, and influence the organisms of higher level. At last, we have discussed the elements that affect the toxicity of harmful algae.
