黄河流域氮磷营养盐动态特征及主要影响因素

收集了黄河流域下游主要干流监测站近40a来(氮数据)或20a(磷数据)来的水质数据,同时,收集了流域各省人口、氮肥磷肥施用量(折纯)及工业废水排放量等数据,研究了黄河氮磷营养盐通量(或浓度)的多年变化趋势,并统计了水质变化与流域人口、化肥用量和工业废水排放量等社会经济指标的关系.结果表明,黄河氮输送通量近40a来有不断升高的趋势,但1990s后期受黄河断流影响有明显下降;同时,由于下游引黄灌区大量取水使得花园口-利津之间的氮通量相对入海口的氮通量为负值.黄河总磷含量在一定范围内波动,没有呈现趋势性变化,受断流影响1990s后期总磷含量值也明显减小.进一步分析表明,黄河氮输送通量的变化主要受流域内人口、氮肥施用量的影响,而与工业废水排放量没有统计上的相关性;黄河总磷含量和流域人口、磷肥施用量和废水排放量均无相关性,而与黄河水体中悬浮物含量显著相关.回归分析结果表明,黄河水体悬浮物中的总磷含量为0.54g·kg-1,与黄土高原总磷背景值十分接近.由于黄河悬浮物主要来自黄土高原,故判断黄河总磷输送的主要影响因素是黄土高原的水土流失.查明黄河流域氮磷输送量多年变化情况和主要影响因素可为流域和海域污染控制及负荷分配提供依据.

Variation and influence factors of nitrogen and phosphorus transportation by the Yellow River

Water quality data of latest 40 years(for nitrogen)or 20 years(for phosphorus)in the lower reaches of the Yellow River,as well as population,nitrogen and phosphorus fertilizer,industrial wastewater data of the Yellow River basin,were collected.The variations of nitrogen and phosphorus transportation in the last decades were studied and their relationships with population,applied fertilizers and wastewater discharged in the basin were analyzed.The results showed that nitrogen transportation in the Yellow River had an increasing trend during the last 40 years,however,it declined considerably in the later 1990s due to the desiccation of the Yellow River.As concerning the estuary,the nitrogen contribution from Huayuankou to Lijin was minus due to the huge amount of water diversion from the Yellow River for irrigating use.The phosphorus contents fluctuated in a certain range without tendency and also decreased in the later 1990s due to the desiccation.Further analyses indicated that the nitrogen transportation in the Yellow River was mostly influenced by the population and nitrogen fertilizer application,but showed no statistically significant relationship with wastewater load;in contrast,the total phosphorus contents in the Yellow River showed no relationship with population,phosphorus fertilizer use and wastewater load in the basin,but presented statistically significant relationship with suspended solid concentrations of the Yellow River.Calculation by regression equation indicated that the phosphorus content in suspended solids of the Yellow River was 0.54g·kg^-1,which was quite close to the Pbackground value in the soil from the Loess Plateau.Therefore,it was concluded that phosphorus transportation in the Yellow River was dominantly influenced by the soil erosion from the Loess Plateau.The results of this study can supply basis for the total nutrient load control and load allocation in the watershed and marine areas.