2009-2018年太湖大气湿沉降氮磷特征对比研究

为了研究太湖2009-2018年大气湿沉降的时空变化特征，于2009年8月-2010年7月及2017年8月-2018年7月进行了两次环太湖大气湿沉降逐月调查，并从降水中ρ（TN）和ρ（TP）、湿沉降率及沉降通量三方面，对比分析了太湖大气湿沉降的时空变化特征.结果表明:①2009年8月-2010年7月降水中ρ（TN）、ρ（TP）平均值分别为3.170、0.077 mg/L；2017年8月-2018年7月降水中ρ（TN）、ρ（TP）平均值分别为3.160、0.056 mg/L；T检验结果表明，两次调查ρ（TN）、ρ（TP）污染水平差异显著，主要是由于2017年8月-2018年7月较高污染浓度降水事件的减少，全年降水中ρ（TN）、ρ（TP）变异较小.②与2017年8月-2018年7月相比，2009年8月-2010年7月太湖TN、TP湿沉降率平均值分别下降33%和53%，且TN、TP湿沉降空间分布更均匀.③与2009年8月-2010年7月相比，2017年8月-2018年7月太湖流域大气TN、TP沉降通量分别为7 641和131 t，分别下降30%、47%.研究显示，两次调查降水中ρ（TN）平均值均远高于水体富营养化阈值（0.2 mg/L），因此大气湿沉降中的营养盐对太湖富营养化的贡献不可忽视. 

Comparative Study on Nitrogen and Phosphorus Characteristics of Atmospheric Wet Deposition in Lake Taihu from 2009 to 2018

In order to better show the characteristics of atmospheric wet deposition in the Lake Taihu Basin in the past ten years, based on the wet deposition investigation in Lake Taihu from August 2009 to July 2010 and from August 2017 to July 2018, variation trends of nitrogen and phosphorus in the wet deposition were analyzed from the three perspectives of precipitation TN, TP concentration, wet deposition rate and deposition flux. The results showed that:(1) The average concentration of TN and TP from August 2009 to July 2010 was 3.170 and 0.077 mg/L, and 3.160 and 0.056 mg/L from August 2017 to July 2018, respectively. The results of T test showed that the two annual TN and TP pollution levels were significantly different, mainly due to the decrease of high pollution concentration precipitation events from 2017 to 2018. The variation of annual precipitation in the TN and TP became smaller and tended to stabilize; (2) In the two wet deposition surveys, the average wet deposition rates of TN and TP from August 2017 to July 2018 decreased by 33% and 53%, respectively, compared with those from August 2009 to July 2010. The spatial distribution of TN and TP wet deposition in the Lake Taihu Basin from August 2017 to July 2018 tended to be stable. (3) From August 2017 to July 2018, the atmospheric wet deposition fluxes of TN and TP in the Lake Taihu Basin were 7641 and 131 t, respectively. Compared with the reported values from 2009 to 2010, TN deposition flux decreased by 30% and TP deposition flux decreased by 47%. In general, due to the reduction of high pollution concentration precipitation events from August 2017 to July 2018, the spatial distribution was more uniform, and the quality of precipitation water from August 2017 to July 2018 was better than that from August 2009 to July 2010. The studies show that the average concentration of TN in the two surveys was far higher than the value of eutrophication threshold (0.2 mg/L), so the nutrients from atmospheric deposition are a contributor to the eutrophication of Lake Taihu that cannot be ignored.