岷江中游成都段河流无机氮形态影响因素初步分析

Preliminary Analysis on Factors Influencing the Speciation of Inorganic Nitrogen in the Chengdu Section of the Middle Reaches of the Min River

近年来岷江呈现出明显的氮污染不断加剧的趋势。我们依据2006～2008年采集测量的水质数据,采用灰色关联度对岷江中游成都段河流中无机氮形态的影响因素以及相关性进行了初步分析。结果表明:在丰水期、枯水期以及全年尺度上,水温是影响水体中无机氮形态组成,尤其是氨氮(AN)、总无机氮(TIN)中氮元素质量比(m(AN)/m(TIN)的最主要的限制因素,且水温同m(AN)/m(TIN)之间呈负相关;在丰水期和全年尺度上,水体中pH值对m(AN)/m(TIN)的影响仅次于水温,前者呈负相关,后者呈正相关;在枯水期尺度上,pH值对于m(AN)/m(TIN)的影响位居水温和溶解氧(DO)之后,两者之间呈现正相关;DO对m(AN)/m(TIN)的影响在不同的时间尺度上是不相同的。在枯水期尺度上,DO对m(AN)/m(TIN)的影响较大,仅次于水温,而在丰水期和全年尺度上,DO对m(AN)/m(TIN)的影响位居水温和pH值之后,但是DO与m(AN)/m(TIN)之间在3个时间尺度上均呈现负相关;水体中的化学需氧量(COD)通过刺激异养细菌生长消耗溶解氧间接抑制自养的硝化细菌的生长,COD含量与m(AN)/m(TIN)在不同的时间尺度上均呈现正相关;水体中的碱度含量均能够满足氨氮的硝化所需,为硝化过程的非限制性因素。

The Min River has shown a clear trend of continuous pollution of nitrogen in recent years. Based on the water quality data measured from 2006 to 2008, grey relational analysis （GRA） is used to analyze factors influencing the speciation of inorganic nitrogen in the Chengdu section of the middle reaches of the Min River. The results show that water temperature is the most restrictive factor for the speciation of inorganic nitrogen in three differ- ent scales ： wet season, dry season and the entire year. It is negatively correlated with the ratio of ammonia-nitrogen to total inorganic nitrogen contents [m（AN）/m（TIN）]. In the scales of wet season and the entire year, the pH value is the second restrictive factor to the m （AN）/m （TIN）. The former is a negative correlation and the latter a positive correlation. In dry season, the impact of pH on the m（AN）/m（TIN） is after water temperature and dis- solved oxygen （DO）, and it is positively correlated. The DO has different influences in different seasons. In dry season, the DO is the second restrictive factor. But in the scales of wet season and the entire year, the influence of the DO on the m （AN）/ra （TIN） is next to water temperature and pH. All three scales are negatively correlated with the m （AN）/m （TIN）. The heterotrophic bacteria, simulated by the COD content in water column, consume oxygen and indirectly inhibit the growth of autotrophic bacteria in water bodies, the m（ AN）/m（TIN） is positively correlated with the COD in different time scales. Since the alkalinity in water column is suitable for nitrification in the fiver, it is not restrictive factor.