抚仙湖水体中磷的分布特征及其影响因素

 深水湖泊通常具有水体交换周期长、污染物滞留率高、垂向水温分层等特征，水质参数的分布具有明显的时空变异性。以2009年5月和7月的两次现场水质调查数据为基础，结合入湖污染源和湖泊自身的水动力条件，深入探讨了抚仙湖水体中磷的水平、垂直分布特征以及入湖污染源和水动力条件的影响，结果表明：表层水体中总磷（TP）的空间分布及其变化与抚仙湖风生流场和入湖污染源的分布特征具有较好的一致性；雨季降雨径流携带了大量的污染物和泥沙入湖，导致7月表层水体中TP质量浓度较5月明显增加；降雨径流污染主要影响浅层水体，对100 m以下深层水体的影响较小；水体中TP质量浓度有沿水深逐渐增高的趋势，深层水体中磷的蓄积较重，并有加剧趋势。底部“磷库”的存在对湖泊水质存在较大的潜在威胁，需引起高度重视。

Distribution characteristics of phosphorus in the water of Lake Fuxian and its influencing factors

Deep lakes usually have long water exchange period, high pollutant retention rate, and vertical thermal stratification,therefore large spatiotemporal variability may exist in the water body. Based on the two field surveys in May and July 2009 to investigate the horizontal and vertical variations of phosphorus in Lake Fuxian, the influences of main polluting sources and hydrodynamic conditions are analyzed and the distributions of phosphorus in the lake are studied. Results show that the distribution of TP in the surface water agrees with the wind-induced surface flow and the distribution of main polluting sources. The concentrations of TP in the surface water in July are obviously larger than those in May, which is mainly caused by pollutants in runoff in the rainy season. However, the water below 100 m and more is less affected by the runoff pollutions. Besides, TP concentration has an increasing trend along the water depth. The accumulation of phosphorus in deep water is heavy and the situation is getting more serious. The existence of "a phosphorus pool" at the bottom is a big potential threat to the whole water body, which needs more attention.