北里湖总氮、总磷主要输入外源辨识

为了确定影响杭州西湖的主要污染源,以相对封闭的西湖北里湖为研究对象,通过在沿湖路面设置采样点以及在湖中设置大气沉降采样点,对路面及大气入湖的N和P进行监测、估算,结果表明:(a)各月大气总沉降中TN及TP的输入变化趋势不明显,但干沉降中TN及TP的输入却有着明显的春、夏差异;3—8月北里湖TN输入量为1202.20kg,TP输入量为15.02kg.(b)沿岸人行道路面由草地及不透水路面构成,路面灰尘以细颗粒(d<150μm)物质为主,可占总量的79.12%~90.04%;不同粒级组的灰尘中TN含量呈现以下规律:细颗粒组(28μm≤d<150μm)>极细颗粒组(d<28μm)>粗颗粒组(d≥150μm),但TN含量分布特征不明显.(c)草地的N和P输出通过输出系数法估算,不透水路面的N和P输出通过模拟路面灰尘的累积、冲刷进行估算,得到2010年3—8月北里湖来自沿岸人行道的TN输入量为60.13kg,TP输入量为12.52kg.分析结果表明,大气沉降是北里湖N输入的主要外源,同时也是湖水中P的相对重要的来源.

Identification of major exogenous sources of TN and TP in Beili Lake

In order to identify the main pollution sources of Xihu Lake,Beili Lake,which is relatively enclosed and part of Xihu Lake,was selected as a research focus.The amounts of N and P from the road and atmosphere in the lake were monitored and assessed by setting up road dust sampling sites on the lakeside road and atmospheric deposition sampling sites in the middle of the lake.The results show the following:(a) The monthly input variations of TN and TP in total atmospheric deposition were not significant.However,significant differences could be observed in the dry deposition between spring and summer.The TN and TP inputs into Beili Lake from March to August were 1 202.20 kg and 15.02 kg,respectively.(b) The lakeside pavement was made up of grassland and impervious road surface.The road dust mainly consisted of granules(d<150 μm),accounting for 79.12% to 90.04% of the total amount of dust.The content of TN in different grades of dust decreased in the following order: fine granule material(28 μm≤d<150 μm),superfine granule material(d<28 μm),and coarse-grained granule material(d≥150 μm).The distribution of TN content presented no significant features.(c) The N and P outputs from grassland were assessed by the export coefficient model,and the N and P outputs from the impervious road surface were assessed through simulation of build-up and wash-off processes on the impervious road surface.The TN and TP inputs into Beili Lake from the lakeside pavement from March to August in 2010 were 60.13 kg and 12.52 kg,respectively.The analysis results show that atmospheric deposition was the main exogenous source of the N input and a comparatively important source of the P input into Beili Lake.