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
净初级生产力(NPP)是评价森林生态系统碳收支状况的重要指标,精确评估森林NPP变化以应对气候变化有着重要意义。以江西省修河流域为研究区,基于参数本地化后的Biome-BGC模型模拟了1960—2021年6种亚热带典型森林NPP动态变化,并结合温度...净初级生产力(NPP)是评价森林生态系统碳收支状况的重要指标,精确评估森林NPP变化以应对气候变化有着重要意义。以江西省修河流域为研究区,基于参数本地化后的Biome-BGC模型模拟了1960—2021年6种亚热带典型森林NPP动态变化,并结合温度、降水及气候变化情景分析了森林NPP对温度、降水的响应。结果表明:(1)1960—2021年,修河流域不同森林类型的NPP由高到低依次为:竹林(655.20 g C·m^(-2)·a^(-1))>常绿针叶林(629.42 g C·m^(-2)·a^(-1))>常绿阔叶林(600.01 g C·m^(-2)·a^(-1))>常绿针阔混交林(596.98 g C·m^(-2)·a^(-1))>落叶阔叶林(325.20 g C·m^(-2)·a^(-1))>灌木林(266.43 g C·m^(-2)·a^(-1))。(2)6种典型森林NPP的月际变化表明,落叶阔叶林NPP呈单峰变化并在8月份达到最高值,其他森林NPP均在8月份降至峰谷并呈双峰趋势。除落叶阔叶林和灌木林以外,其他森林NPP在7—9月与温度大多呈极显著负相关性,而与降水呈正相关,表明夏季温度升高、降水减少极大影响了植被生长。(3)从气象因子的拟合强度来看,NPP对温度的响应强度大于降水,温度与竹林NPP及落叶阔叶林NPP的拟合较强(R^(2)>0.46;P<0.01);而降水与常绿针叶林、竹林、灌木林及阔叶落叶林NPP都是较弱的拟合关系(R^(2)<0.21;P<0.01)。(4)未来气候情景中,适当升温有助于促进植被的生长,但升温超过阈值后NPP将受到抑制;在降水情景中,NPP与降水呈正相关性。NPP对温度的响应幅度远大于降水,且温度和降水的组合变化情景的拟合优度高于单一变化情景。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.
文摘净初级生产力(NPP)是评价森林生态系统碳收支状况的重要指标,精确评估森林NPP变化以应对气候变化有着重要意义。以江西省修河流域为研究区,基于参数本地化后的Biome-BGC模型模拟了1960—2021年6种亚热带典型森林NPP动态变化,并结合温度、降水及气候变化情景分析了森林NPP对温度、降水的响应。结果表明:(1)1960—2021年,修河流域不同森林类型的NPP由高到低依次为:竹林(655.20 g C·m^(-2)·a^(-1))>常绿针叶林(629.42 g C·m^(-2)·a^(-1))>常绿阔叶林(600.01 g C·m^(-2)·a^(-1))>常绿针阔混交林(596.98 g C·m^(-2)·a^(-1))>落叶阔叶林(325.20 g C·m^(-2)·a^(-1))>灌木林(266.43 g C·m^(-2)·a^(-1))。(2)6种典型森林NPP的月际变化表明,落叶阔叶林NPP呈单峰变化并在8月份达到最高值,其他森林NPP均在8月份降至峰谷并呈双峰趋势。除落叶阔叶林和灌木林以外,其他森林NPP在7—9月与温度大多呈极显著负相关性,而与降水呈正相关,表明夏季温度升高、降水减少极大影响了植被生长。(3)从气象因子的拟合强度来看,NPP对温度的响应强度大于降水,温度与竹林NPP及落叶阔叶林NPP的拟合较强(R^(2)>0.46;P<0.01);而降水与常绿针叶林、竹林、灌木林及阔叶落叶林NPP都是较弱的拟合关系(R^(2)<0.21;P<0.01)。(4)未来气候情景中,适当升温有助于促进植被的生长,但升温超过阈值后NPP将受到抑制;在降水情景中,NPP与降水呈正相关性。NPP对温度的响应幅度远大于降水,且温度和降水的组合变化情景的拟合优度高于单一变化情景。
