| 植物营养物 |
| 添加时间：2019/4/20 15:03:30 浏览次数： |
| 植物营养物主要指氮、磷等能刺激藻类及水草生长、干扰水质净化，使BOD5升高的物质。水体中营养物质过量所造成的"富营养化"对于湖泊及流动缓慢的水体所造成的危害已成为水源保护的严重问题。 Plant nutrients mainly refer to substances such as nitrogen and phosphorus that can stimulate the growth of algae and aquatic plants, interfere with water purification and increase BOD5. The harm of eutrophication caused by excessive nutrients to lakes and slow-flowing water bodies has become a serious problem of water source protection. 富营养化（eutrophication）是指在人类活动的影响下，生物所需的氮、磷等营养物质大量进入湖泊、河口、海湾等缓流水体，引起藻类及其他浮游生物迅速繁殖，水体溶解氧量下降，水质恶化，鱼类及其他生物大量死亡的现象。在自然条件下，湖泊也会从贫营养状态过渡到富营养状态，沉积物不断增多，先变为沼泽，后变为陆地。这种自然过程非常缓慢，常需几千年甚至上万年。而人为排放含营养物质的工业废水和生活污水所引起的水体富营养化现象，可以在短期内出现。 Eutrophication refers to the phenomenon that under the influence of human activities, nutrients such as nitrogen and phosphorus needed by organisms enter lakes, estuaries, bays and other slow-flowing waters in large quantities, causing rapid reproduction of algae and other plankton, decline of dissolved oxygen in water, deterioration of water quality, and mass death of fish and other organisms. Under natural conditions, lakes also transit from poor nutrition to eutrophication, and sediments increase continuously, first into marshes, then into land. This natural process is very slow, often taking thousands or even tens of thousands of years. The eutrophication of water caused by the artificial discharge of industrial wastewater and domestic wastewater containing nutrients can occur in a short period of time. 植物营养物质的来源广、数量大，有生活污水（有机质、洗涤剂）、农业（化肥、农家肥）、工业废水、垃圾等。每人每天带进污水中的氮约50g。生活污水中的磷主要来源于洗涤废水，而施入农田的化肥有50%～80%流入江河、湖海和地下水体中。天然水体中磷和氮（特别是磷）的含量在一定程度上是浮游生物生长的控制因素。当大量氮、磷植物营养物质排入水体后，促使某些生物（如藻类）急剧繁殖生长，生长周期变短。藻类及其他浮游生物死亡后被需氧生物分解，不断消耗水中的溶解氧，或被厌氧微生物所分解，不断产生硫化氢等气体，使水质恶化，造成鱼类和其他水生生物的大量死亡。藻类及其它浮游生物残体在腐烂过程中，又把生物所需的氮、磷等营养物质释放到水中，供新的一代藻类等生物利用。因此，水体富营养化后，即使切断外界营养物质的来源，也很难自净和恢复到正常水平。水体富养化严重时，湖泊可被某些繁生植物及其残骸淤塞，成为沼泽甚至干地。局部海区可变成"死海"，或出现"赤潮"现象。 Plant nutrients come from a wide range of sources and large quantities, including domestic sewage (organic matter, detergent), agriculture (fertilizer, farm manure), industrial wastewater, garbage and so on. Each person brings about 50 g of nitrogen into the sewage every day. Phosphorus in domestic sewage mainly comes from washing wastewater, while 50%-80% of fertilizer applied to farmland flows into rivers, lakes, seas and groundwater. The content of phosphorus and nitrogen (especially phosphorus) in natural waters is a controlling factor for the growth of plankton to a certain extent. When a large number of nitrogen and phosphorus plant nutrients are discharged into the water body, some organisms (such as algae) grow rapidly and the growth cycle becomes shorter. After the death of algae and other plankton, they are decomposed by aerobic organisms, consuming dissolved oxygen in water, or being decomposed by anaerobic microorganisms, and producing hydrogen sulfide and other gases, which deteriorates the water quality and causes a large number of deaths of fish and other aquatic organisms. In the process of decay, algae and other plankton residues release nutrients such as tance.37ix.com.cnpenquan.37ix.com.cndiaosu.37ix.com.cnpaiwubeng.37ix.com.cnnitrogen and lajitong.71ix.combaozhuangdai.37ix.com.cnphosphorus needed by organisms into water for the utilization of new generation of algae and other organisms. Therefore, after eutrophication, even if the source of nutrients is cut off, it is difficult to self-purification and return to normal level. When water eutrophication is serious, lakes can be silted up by some plants and their debris and become swamps or even dry land. Local sea areas can be changed into "Dead Sea" or "Red Tide" phenomenon. 常用氮、磷含量，生产率（O2）及叶绿素-α作为水体富营养化程度的指标。表3-7是用总磷、无机氮划分水体富养化程度的指标。防治富营养化，必须控制进入水体的氮、磷含量。 Nitrogen and phosphorus content, productivity (O 2) and chlorophyll-a are commonly used as indicators of eutrophication. Tables 3-7 are indicators of the degree of eutrophication of water bodies using total phosphorus and inorganic nitrogen. In order to prevent eutrophication, the content of nitrogen and phosphorus entering water must be controlled. |
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