[Spatio-temporal changes of nitrogen balance in 1980-2005 for agricultural land in Three Gorges Reservoir Area].

Based on the long-term agricultural statistics data at the county scale, the estimation of nitrogen balance from 1980 to 2005 for agricultural land in Three Gorges Reservoir Area was made by the OECD soil surface nitrogen balance model with some suitable modification. The spatio-temporal changes of nitrogen balance and its drivers were analyzed. The results showed that the total inputs and total surplus of nitrogen from 1980 to 2005 presented increasing trends continuously, from 23.

[Estimated nutrient export loads based on improved export coefficient model in Xitiaoxi watershed].

It is very important to estimate nutrient export loads from watershed, which is beneficial to water environmental management. The export coefficients for major land use types were evaluated by field surveying data, in addition the spatial distributions of precipitation and runoff were considered, to improve on export coefficient model (ECM), then integrated ECM into geographical information system to compose half-distribution model of export coefficients. Estimated nutrients export loads based on the ECM in Xitiaoxi watershed located upper of Taihu Lake area.

[Characteristics of soil phosphorus runoff under different rainfall intensities in the typical vegetable plot of Taihu Basin].

Experiments of field runoff plots, which were conducted at vegetable plots in Hongsheng town of Wuxi city--the typical region of Taihu Basin, were designed to assess the effects of different rainfall intensities on soil phosphorus runoff loss from vegetable plots by artificial rainfall simulations. Results showed that there was a relationship of power function between initial runoff-generation time and rainfall intensity. Runoff amount slowly increased under small rainfall intensity, but rapidly increased with rainfall intensity increase.

[Analysizing and quantitatively evaluating the organic matter source at different ecologic zones of tidal salt marsh, North Jiangsu Province].

The indicators including TOC, TN, C/N, delta 13C and delta 15N of surface sediments, core sediments and plants of tidal salt marshes in North Jiangsu Province are analysized.Subsequently, distribution regularities of these measurement indicators are discussed, and the biogeochemistry processes between sediments and plants are also analysized. Lastly, the organic matter sources of different ecologic zones in tidal salt marsh are evaluated, and the organic matter accumulations in different ecologic zones induced by their plants are also compared.