With the impoundment of the Three Gorges Reservoir, algal blooms have been found in some tributaries. In this study, according to the theoretical analysis of the eutrophication mechanism in a river-type reservoir trib...With the impoundment of the Three Gorges Reservoir, algal blooms have been found in some tributaries. In this study, according to the theoretical analysis of the eutrophication mechanism in a river-type reservoir tributary, a one-dimensional eutrophication model was developed for the Xiangxi River tributary of the Three Gorges Reservoir, and the influence of hydrodynamic conditions on the primary growth rate of algae was investigated. Furthermore, numerical predictions of hydraulic variables and eutrophication factors, such as the concentration distribution of TP, TN, and Chl-a in the spatial and temporal domains, were carried out. Comparison of computation results of TP, TN, and Chl-a concentrations along the river in the spring of 2005 with experimental data demonstrates the validity of the model. The agreement between the computation results and the experimental data of TP and TN concentrations is better than the agreement between those of Chl-a concentration. The simulated results also show that the Chl-a concentration downstream is much higher than that in the upstream tributary, which potentially indicates the outbreak of algae in this area. Therefore, this study provides a feasible method of accurately predicting the state of eutrophication in river-type reservoirs and their tributaries.展开更多
The modem term 'agroforestry system' is derived from agricultural practices. It is an organic combination of agriculture and forestry, ecology and economy, product variation and scientific management. On the b...The modem term 'agroforestry system' is derived from agricultural practices. It is an organic combination of agriculture and forestry, ecology and economy, product variation and scientific management. On the basis of analyzing the types and structure of agroforestry system in the Three Gorges Reservoir area,the paper poins out that agroforestry system can be divided into diffend structutal levds. Taking some typical cases as examples, it compares the benefits of four kinds of structures. The result illustrates that the hedge row agroforestry system on slopeland is an effective way to realize coordinate development of ecology and economy.展开更多
Carbon dioxide(CO_2) emission from the rivertype reservoir is an hotspot of carbon cycle within inland waters. However, related studies on the different types of reservoirs are still inadequate. Therefore, we sampled ...Carbon dioxide(CO_2) emission from the rivertype reservoir is an hotspot of carbon cycle within inland waters. However, related studies on the different types of reservoirs are still inadequate. Therefore, we sampled the Three Gorges Reservoir(TGR), a typical river-type reservoir having both river and lake characteristics, using an online system(HydroCTM/CO_2) and YSI-6600v2 meter to determine the partial pressure of carbon dioxide(pCO_2)and physical chemical parameters in 2013. The results showed that the CO_2 flux from the mainstream ranged from 26.1 to 92.2 mg CO_2/m^2h with average CO_2 fluxes of 50.0 mg/m^2h. The CO_2 fluxes from the tributary ranged from-10.91 to 53.95 mg CO_22/mh with area-weighted average CO_2 fluxes of 11.4 mg/m^2h. The main stream emits CO_2 to the atmosphere the whole year; however, the surface water of the tributary can sometimes act as a sink of CO_2 for the atmosphere. As the operation of the TGR, the tributary became more favorable to photosynthetic uptake of CO_2 especially in summer. The total CO_2 flux was estimated to be 0.34 and 0.03 Tg CO_2/year from the mainstream and the tributaries, respectively. Our emission rates are lower than previous estimates, but they are in agreement with the average CO_2 flux from temperate reservoirs estimated by Barros et al.(Nat Geosci 4(9):593–596, 2011).展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 50779028)the National Science and Technology Supporting Plan (Grant No. 2008BAB29B09)
文摘With the impoundment of the Three Gorges Reservoir, algal blooms have been found in some tributaries. In this study, according to the theoretical analysis of the eutrophication mechanism in a river-type reservoir tributary, a one-dimensional eutrophication model was developed for the Xiangxi River tributary of the Three Gorges Reservoir, and the influence of hydrodynamic conditions on the primary growth rate of algae was investigated. Furthermore, numerical predictions of hydraulic variables and eutrophication factors, such as the concentration distribution of TP, TN, and Chl-a in the spatial and temporal domains, were carried out. Comparison of computation results of TP, TN, and Chl-a concentrations along the river in the spring of 2005 with experimental data demonstrates the validity of the model. The agreement between the computation results and the experimental data of TP and TN concentrations is better than the agreement between those of Chl-a concentration. The simulated results also show that the Chl-a concentration downstream is much higher than that in the upstream tributary, which potentially indicates the outbreak of algae in this area. Therefore, this study provides a feasible method of accurately predicting the state of eutrophication in river-type reservoirs and their tributaries.
文摘The modem term 'agroforestry system' is derived from agricultural practices. It is an organic combination of agriculture and forestry, ecology and economy, product variation and scientific management. On the basis of analyzing the types and structure of agroforestry system in the Three Gorges Reservoir area,the paper poins out that agroforestry system can be divided into diffend structutal levds. Taking some typical cases as examples, it compares the benefits of four kinds of structures. The result illustrates that the hedge row agroforestry system on slopeland is an effective way to realize coordinate development of ecology and economy.
基金funded by the National Natural Science Foundation of China (No.41573064)The National Key Research and Development Program of China (No.2016YFA0601003)the Special S&T Project on Treatment and Control of Water Pollution (No.2012ZX07104-001)
文摘Carbon dioxide(CO_2) emission from the rivertype reservoir is an hotspot of carbon cycle within inland waters. However, related studies on the different types of reservoirs are still inadequate. Therefore, we sampled the Three Gorges Reservoir(TGR), a typical river-type reservoir having both river and lake characteristics, using an online system(HydroCTM/CO_2) and YSI-6600v2 meter to determine the partial pressure of carbon dioxide(pCO_2)and physical chemical parameters in 2013. The results showed that the CO_2 flux from the mainstream ranged from 26.1 to 92.2 mg CO_2/m^2h with average CO_2 fluxes of 50.0 mg/m^2h. The CO_2 fluxes from the tributary ranged from-10.91 to 53.95 mg CO_22/mh with area-weighted average CO_2 fluxes of 11.4 mg/m^2h. The main stream emits CO_2 to the atmosphere the whole year; however, the surface water of the tributary can sometimes act as a sink of CO_2 for the atmosphere. As the operation of the TGR, the tributary became more favorable to photosynthetic uptake of CO_2 especially in summer. The total CO_2 flux was estimated to be 0.34 and 0.03 Tg CO_2/year from the mainstream and the tributaries, respectively. Our emission rates are lower than previous estimates, but they are in agreement with the average CO_2 flux from temperate reservoirs estimated by Barros et al.(Nat Geosci 4(9):593–596, 2011).
