Correll D L
Smithsonian Environmental Research Center, Edgewater, Maryland 20137, USA.
Poult Sci. 1999 May;78(5):674-82. doi: 10.1093/ps/78.5.674.
Phosphorus is an essential element for all life forms. It is a mineral nutrient. Orthophosphate is the only form of P that autotrophs can assimilate. Extracellular enzymes hydrolyze organic forms of P to phosphate. Eutrophication is the over-enrichment of surface waters with mineral nutrients. The results are excessive production of autotrophs, especially algae and cyanobacteria. This high productivity leads to high bacterial populations and high respiration rates, leading to hypoxia or anoxia in poorly mixed bottom waters and at night in surface waters during calm, warm conditions. Low dissolved oxygen causes the loss of aquatic animals and the release of many materials normally bound to bottom sediments, including various forms of P. This release of P reinforces the eutrophication. Excessive concentrations of P is the most common cause of eutrophication in freshwater lakes, reservoirs, streams, and in the headwaters of estuarine systems. In the ocean, N is believed to usually be the key mineral nutrient controlling primary production. Estuaries and continental shelf waters are a transition zone, in which excessive P and N create problems. It is best to measure and regulate total P inputs to whole aquatic ecosystems, but for an easy assay it is best to measure total P concentrations, including particulate P, in surface waters or N:P atomic ratios in phytoplankton.
磷是所有生命形式的必需元素。它是一种矿物质营养素。正磷酸盐是自养生物能够同化的唯一磷形式。细胞外酶将有机磷形式水解为磷酸盐。富营养化是地表水矿物质营养素过度富集的现象。其结果是自养生物过度繁殖，尤其是藻类和蓝细菌。这种高生产力导致细菌数量增加和呼吸速率升高，在底部水体混合不良以及平静温暖条件下的夜间表层水体中会导致缺氧或无氧状态。低溶解氧会导致水生动物死亡，并释放出许多通常与底部沉积物结合的物质，包括各种形式的磷。这种磷的释放会加剧富营养化。磷浓度过高是淡水湖泊、水库、溪流以及河口系统上游富营养化最常见的原因。在海洋中，氮通常被认为是控制初级生产力的关键矿物质营养素。河口和大陆架水域是一个过渡区域，其中过量的磷和氮会引发问题。最好测量并调节整个水生生态系统的总磷输入量，但为了便于分析，最好测量表层水体中的总磷浓度（包括颗粒磷）或浮游植物中的氮磷原子比。
