珠江口咸淡水交汇区营养盐的化学自净研究

A STUDY ON CHEMICAL SELF-PURIFICATION OF NUTRIENTS IN THE MIXING REGION OF SALT AND FRESH WATER OF ZHUJIANG RIVER ESTUARY

珠江口咸淡水交汇区是河流污染物质的集散地。为了揭示营养盐（氮、磷）在河口区复杂的化学自净过程，深入了解其微妙变化，首次用珠江口咸淡水交汇区采集的水和沉积物，在香港浸会学院进行自净试验，探索其自净过程和变化规律。

ome conclusions can be drawn up on the basis of the experiment results:The contents of nitrogen and phosphorus in the water body decrease with the prolongation of time. NO3-N content decreases more rapidly in the water with lower salinity, but the salinity does not give obvious effect on the decrement of NO2-N, NH4-N and PO4-P contents, the transformation of nitrogen in rapid flowing water is faster than that in slow flowing water.The self-purification of nutrients (nitrogen and phosphorus) in water body takes place more rapidly on the first day, especially in the first six hours from the begining of the experiments, the most obvious self-purifications occur for NO3-N and PO4-P.Half decay time (D50%) of NO3-N, NO2-N and NH4-N are 0. 7-5.3, 1-8 and 1-3. 2 days, respectively, but it is rather longer for PO4-P, amounting to 5. 7-8. 2 days.90% decrement of their contents (D90% ) takes more than 12 days (except NH4-N).9.3% of the added inorganic phosphorus and 28.6% of added inorganic nitrogen are deposited, the sedimentation percentages of nitrogen and phosphorus are in proportion to the content of suspended matters but in reverse proportion to the content of organic matters.