Shallow fresh water bodies in peat areas could be an important contributor to greenhouse gases in the atmosphere.In this study,the partial pressure of CO2 in the surface water of the Dianshan Lake was investigated insitu in August 2011.The average pCO2 in the study area was 2300μatm and fluctuated within the range of 989–5000μatm.pCO2 showed a reverse trend to the variations of pH and DO in the surface water of the Dianshan Lake.The water to air diffusion flux of CO2 of the upstream,middle lake and downstream were respectively 63,33 and 14mmol/m2/d.On average,the diffusion flux of CO2 of the whole lake was 31 mmol/m2/d.Consequently,our results show that during the sampling season,the Dianshan Lake appears to be a great source of CO2.It is also demonstrated that respiration could be the dominant biochemical reaction in the Dianshan Lake in summer.
Currently, most rivers worldwide have been intensively impounded. River damming becomes a big problem, not only in inducing the physical obstruction between upstream and downstream, but also in destroying the natural continuity of river. But the discontinuity of water quality was often neglected, which presents a challenge to traditional river geochemistry research. To understand the changes in basic chemistry of water upstream and downstream of the dam, we investigated the Miaotiao River reservoirs in series in the Wujiang River Basin, and the Hongjiadu, Dongfeng Reservoir on the upper reaches of the Wujiang River. Chemical weathering rates were calculated using the water chemistry data of the reservoir surface and downstream of the dam, in each reservoir, respectively. The results showed that the difference between the chemical weathering rates calculated from reservoir surface water and water downstream of the dam was greater in reservoirs with a longer water retention time. In Hongjiadu Reservoir with the longest water retention time among the studied reservoirs, this difference reaches 9%. As a result, the influence of fiver damming, especially the influence of reservoirs in series, should be taken into account when calculating the chemical weathering rate of a fiver basin.
Yang GAOBaoli WANGXiaolong LIUYuchun WANGJing ZHANGYanxing JIANG
