| As an important water source protection zone in Shanghai, the area of Dianshan Lake which located in the upper area of Huangpu River is a main source of drinking water for the city, the water quality of Dianshan Lake impacts resident's living and production of shanghai direactly. In recent years, because of the local agricultural non-point source pollution (ANSP), the lake kept a relatively high level of algal bloom in every summer and fall, and its nutrients mainly came from agriculture such as great application and loss of chemical fertilizer on arable lands. Therefore, it is very imporment to study the characteristics and control approach of the regional ANSP for protecting the drinking water source.This research takes the Dalian Lake area as study area, which represents the typical agricultural production mode in Dianshan Lake area, the non-point pollutant loss from the two main cropping patterns of Water Bamboo & Rice Rotation and Single Water Bamboo Plant were evaluated, as well as Aquaculture whose area accounted for 77.1% of the agricultural land. The main source of pollution and primary pollutant were obtained by the equal standard pollution load method, and the correlation between the ANSP pollutant discharge and the local water quality was explored. Finally, according to the local ANSP characteristics and domestic & foreign BMPs, the prevention and control approach which were suitable for the ANSP were established. The results are showed as follows:1. With paddy field plot scale experiments, the characteristics of non-point pollutant loss from the Water Bamboo & Rice Rotation and the Single Water Bamboo Plant were studied under conventional fertilization. The pollutants discharged much more from June to September, during this time, the N loss and P loss were 97.5% and 93.6% of the total annual discharge, the pollutant concentrations in runoff water had positive correlations with the fertilizer application. Aquaculture had no obvious non-point pollutant discharge rules because of the inconsistent and irregular drainage, but the pollutant concentrations had a high level in drainage water. Specially, the peak TP concentration was up to 5.59mg/L, mainly came from the fodder which contained a large quantity of phosphorus, so great pollution load has be made.2. According to the typical monitor experiments, the farming discharge loads of COD, TN and TP were 180.15, 119.78 and 1.34kg·hm-2·a-1 respectively, and the Fish Farming discharge loads of COD, TN and TP were 44.16, 2.93 and 2.00 kg·hm-2·a-1 respectively. By the equal standard pollution load method, we got the result that the main pollutant was TP, whose load ratio of equivalent standard reached 63.20%, and the main pollution source was fish ponds whose COD, TN and TP discharge account for 37.19%, 10.29% and 71.68% of the regional total amount. So it is important to control the P discharge from fish ponds.3. By the seasonal water quality monitoring of Dalian Lake and adjacent river, the variation of water quality were studied. The rusults showed that, the TN concentration of the lake in winter and spring was significantly higher than in summer and fall, the average concentrations were 2.97mg/L in winter and 1.53mg/L in summer. In contrast, the TP concentration was significantly higher in summer and fall than in winter and spring, the average concentrations were 0.128mg/L in summer and 0.080mg/L in winter; the seasonal change of COD had low correlation with the local ANSP, and the concentration was always less than 40mg/L. Meanwhile, 7phylums, 40genuses and 65species of algae were observed, and nutrient-rich algae were existed in every season. Additionally, with the Trophic State Index model (TSIm), the TSIm of the lake was above 50 in every season, and reached the peak in summer.4. The environmental impact of the local ANSP on the water was studied, the results showed that, Water Bamboo-Rice Rotation and Water Bamboo Continuous Plant had a large impact on the nitrogen concentration of Dalian Lake in summer and fall, while as the biggest pollution source in Dalian Lake Area, the aquaculture had impacted the TP and COD concentrations of Dalian Lake in summer, fall and winter, and impacted the TN concentration in winter.5. According to characteristics of the local ANSP and the BMPs systems, the prevention and control approach were established. The engineering measures were to transform the existing conventional ditches to eco-ditches, and changed the direction of fish ponds drainage to arable lands, therefore, the waste water could be purified during the runoff process; Among non-engineering measures, the construction of relevant laws and regulations, economic control measures, monitoring of technological innovation and building of effective management were put forward to control the ANSP.
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