Ruxi River is a tributary of the Three Gorges Reservoir. This study examined the temporal and spatial dynamics in particle size characteristics and the associated nutrients and contaminants of the fluvial suspended an...Ruxi River is a tributary of the Three Gorges Reservoir. This study examined the temporal and spatial dynamics in particle size characteristics and the associated nutrients and contaminants of the fluvial suspended and deposited sediments along the Ruxi River. Temporal variations in the particle size distribution of the suspended sediment are controlled mainly by differences in sediment source during different seasons. Total organic carbon (TOC), total nitrogen (TN) and total phosphorous (TP) in the 〈 62 μm fraction of the suspended sediment exhibit considerably higher concentrations in spring, indicating high probability of algal blooms in the backwater areas. Downstream trends in the nutrient contents of 〈 62 pm deposited sediments imply the greatest potential for eutrophication in the backwater ends, where highest nutrient concentrations were detected. Assessment of metal contamination shows that the sediments deposited in the water-level fluctuation zone were moderately to strongly contaminated by Cadmium (Cd), with a considerably high potential ecological risk. The findings reported have emphasized the impacts of reservoir impoundment on aquatic and/or terrestrial environment in this region. More information on physical, chemical and biological processes of sediment and sediment-associated materials are needed for developing ecologically sound policies management. environmentally and of water and sediment展开更多
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
为揭示三峡支流细菌群落的多样性和分布特征,采用高通量16s r DNA测序技术,于2014年5月对大宁河和香溪河细菌进行调查研究,同时检测水环境因子。结果表明,大宁河和香溪河细菌种类丰富,共检出细菌和古生菌25门,其中比例最高的为变形菌门,...为揭示三峡支流细菌群落的多样性和分布特征,采用高通量16s r DNA测序技术,于2014年5月对大宁河和香溪河细菌进行调查研究,同时检测水环境因子。结果表明,大宁河和香溪河细菌种类丰富,共检出细菌和古生菌25门,其中比例最高的为变形菌门,占69.01%,放线菌门其次,占11.46%。变形菌门中,γ-变形菌最多,占该门类总数的35.22%,β-变形菌其次,为22.18%。细菌多样性指数Shannon指数平均为13.2,Simpson指数接近于0,Chao1指数平均为48 633 611.4,可见三峡支流的细菌种类极其多样。几种丰度较高的细菌在空间上具有不同的分布特征。统计分析显示对细菌组成与分布影响最显著的因子为总无机碳,其次是总有机碳、叶绿素,其它因子影响较小。放线菌、γ-变形菌、δ-变形菌和浮霉菌与总有机碳正相关。叶绿体纲细菌和叶绿素含量存在正相关,而变形菌、梭菌纲细菌则与其负相关。变形菌与氮磷和总碳成较强的正相关,所以碳源的增加使变形菌丰度提高。营养水平是影响细菌群落结构的重要因素之一。营养水平越高,α-变形菌比例越高。营养水平低则δ-变形菌比例上升。支流上不同河段的环境因子有明显的空间分布的差异(P<0.05)。这些差异造成了大宁河和香溪河细菌群落结构的空间异质性。展开更多
基金financially supported by the National Natural Science Foundation of China (41430750, 41301293)the National Key R&D Program of China (2017YFD0800505, 2016YFC0402301)
文摘Ruxi River is a tributary of the Three Gorges Reservoir. This study examined the temporal and spatial dynamics in particle size characteristics and the associated nutrients and contaminants of the fluvial suspended and deposited sediments along the Ruxi River. Temporal variations in the particle size distribution of the suspended sediment are controlled mainly by differences in sediment source during different seasons. Total organic carbon (TOC), total nitrogen (TN) and total phosphorous (TP) in the 〈 62 μm fraction of the suspended sediment exhibit considerably higher concentrations in spring, indicating high probability of algal blooms in the backwater areas. Downstream trends in the nutrient contents of 〈 62 pm deposited sediments imply the greatest potential for eutrophication in the backwater ends, where highest nutrient concentrations were detected. Assessment of metal contamination shows that the sediments deposited in the water-level fluctuation zone were moderately to strongly contaminated by Cadmium (Cd), with a considerably high potential ecological risk. The findings reported have emphasized the impacts of reservoir impoundment on aquatic and/or terrestrial environment in this region. More information on physical, chemical and biological processes of sediment and sediment-associated materials are needed for developing ecologically sound policies management. environmentally and of water and sediment
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.
文摘为揭示三峡支流细菌群落的多样性和分布特征,采用高通量16s r DNA测序技术,于2014年5月对大宁河和香溪河细菌进行调查研究,同时检测水环境因子。结果表明,大宁河和香溪河细菌种类丰富,共检出细菌和古生菌25门,其中比例最高的为变形菌门,占69.01%,放线菌门其次,占11.46%。变形菌门中,γ-变形菌最多,占该门类总数的35.22%,β-变形菌其次,为22.18%。细菌多样性指数Shannon指数平均为13.2,Simpson指数接近于0,Chao1指数平均为48 633 611.4,可见三峡支流的细菌种类极其多样。几种丰度较高的细菌在空间上具有不同的分布特征。统计分析显示对细菌组成与分布影响最显著的因子为总无机碳,其次是总有机碳、叶绿素,其它因子影响较小。放线菌、γ-变形菌、δ-变形菌和浮霉菌与总有机碳正相关。叶绿体纲细菌和叶绿素含量存在正相关,而变形菌、梭菌纲细菌则与其负相关。变形菌与氮磷和总碳成较强的正相关,所以碳源的增加使变形菌丰度提高。营养水平是影响细菌群落结构的重要因素之一。营养水平越高,α-变形菌比例越高。营养水平低则δ-变形菌比例上升。支流上不同河段的环境因子有明显的空间分布的差异(P<0.05)。这些差异造成了大宁河和香溪河细菌群落结构的空间异质性。