[Measurement of the CO2 flux on the water-air interface of Taihu Lake].

Based on the measurement of the CO2 flux on the water-air interface of Taihu Lake by closed chamber technique from January 2003 to June 2005, variation characteristics of the CO2 flux on the water-air interface in Taihu Lake are analyzed. Diurnal variation of the CO2 flux on the water-air interface is obvious. The CO2 flux is -0.79 mg/(m2 x h) in spring, -4.89 mg/(m2 x h) in summer, -4.06 mg/(m2 x h) in autumn and -2.56 mg/(m2 x h) in winter. Taihu Lake is the sink of carbon monoxide. The CO2 flux gets larger in severer polluted area of the lake. Seasonal variation is not apparent in the algae type lake, but obvious in grass type lake. It is high in summer and autumn, and low in spring and winter. Correlative factors of CO2 flux on the water-air interface of Taihu Lake possibly include weather, solar radiation, wind velocity, temperature, pH, TA, Chla, TC, TN and TP.

Sedimentation retention basin utilization for best management practice.

Approaches to the artificial impoundment and theoretical design of sedimentation retention basin are reviewed with particular attention to best management practice (BMP) to control agriculture and surface runoff. Sediments retention basins are the small version of farm pond used where a criteria of farm pond is not met. Such basin traps the pollutants and suspended solids prior to entry into streams and lakes. The study is focused with special reference to the assessment and control of non-point source pollution (NPSP) from the sub-basin area of Tai Lake in the Xishan County of Wuxi City of China. The author suggested two different approaches to conduct this study including theoretical design for sedimentation retention basin and computation of flow, sediment transport and deposition during the artificial impoundment of retention basin for BMP's utilization. Theoretical design will provide a useful function as a first line defense against the movement of sediments and transport of pollutants into the Tai Lake while the assessment of sediments deposition will help to make its proper use and periodic cleanup.