Researches on Monitoring Indicators Screening of Intensive Plant Source Pollution in the Plain Area of the Yangtze River Delta

The amount of non-point source pollution from intensive cropping with different patterns (rice, wheat and greenhouse vegetable) were measured by three successive years' field experiments in typical area of Yangtze River Delta. The field experiments results illustrated the losses of ammonia volatilization, surface runoff and leaching were accounted for 15.4%, 5.3% and 1.8% of the applied nitrogen in the rice season and the total loss percentage was about 22.5%. In the wheat season, the losses of ammonia volatilization, surface runoff and leaching were responsible for 3.3%, 5.1% and 3.0% of the applied nitrogen, respectively and the total loss percentage was about 11.4%. By the greenhouse vegetable farming, the losses of ammonia volatilization, surface runoff and leaching were accounted for 0.1%, 3.0% and 18.9% of the applied nitrogen and the total loss percentage was about 22.0%. Based on the field experiments' results, several monitoring indicators were screened to forecast the non-point source pollutions. Specifically, 4 monitoring indicators (ammonium concentration in the flooded water, the daily highest temperature, the TN concentration at the soil depth of 120 cm and rainfall) for rice planting system, 5 monitoring parameters (soil ammonium concentration in the 0-30 cm layer, the daily highest temperature, soil pH, the nitrogen application rate and rainfall) for wheat planting system, and 2 monitoring indexes (the nitrogen application rate and rainfall) for greenhouse vegetable planting system have been proposed in the study. Statistical validation confirmed that these newly developed monitoring indicators can improve the prediction accuracy of non-point source pollution emission. Therefore, this study provides a convenient and effective method of environment monitoring and management for the environmental protection authorities of government.