With the population increasing,fish communities,as important components in the river system,were inescapably impacted by human activities.To investigate these impacts,we characterized the fish community’s composition...With the population increasing,fish communities,as important components in the river system,were inescapably impacted by human activities.To investigate these impacts,we characterized the fish community’s composition by environmental DNA metabarcoding in the urban and suburban sites along Xiang River in central China.The results showed that 32 species were identified,and most species were from Cypriniform.The analysis indicated no significant differences in fish communities among the three urban areas.However,significant differences were observed between the bank solidified and non-solidified areas,which indicated that the channelization significantly influenced the biodiversity and abundances.An alien species,Clarias gariepinus,was discovered in all examined sites,and it was negatively associated with ten native species.Furthermore,human populations and acidification were also negatively related to diversity.Our findings clearly showed that the consequences of anthropogenic activities shaped ichthyofauna and caused biodiversity loss in the urban river.展开更多
Booming urbanization due to a fast-growing population results in more impervious areas, less infiltration,and hence greater flood peak and runoff. Clear understanding of flood responses in regions with different level...Booming urbanization due to a fast-growing population results in more impervious areas, less infiltration,and hence greater flood peak and runoff. Clear understanding of flood responses in regions with different levels and expansions of urbanization is of great importance for regional urban planning. In this study, comparison of flooding responses to urbanization processes in terms of flood peak and runoff volume in the upper, middle,and lower Xiang River Basin(XRB), China, was carried out using the Hydrologic Engineering Center-Hydrologic Modeling System(HEC-HMS) model. From 2005 to 2015, urbanization level and intensity were higher in the lower XRB compared to the upper and middle XRB, and the overall expansion rate of urban areas was 112.8%.Modeling results by the HEC-HMS model indicate elevated flood peak discharges and volumes due to fast urbanization in the XRB from the 1980 s to 2015. This rapid increase is particularly the case in the lower XRB. The study also revealed different hydrological responses of flood regimes—urbanization tends to have larger impacts on peak flood flow rather than on flood volume in the lowerXRB, which further corroborated urbanization-induced intensifying flood processes in terms of peak flood flow.Urbanization has increasing impacts on flood volume from the upper to the lower XRB, which can be attributed to accumulated runoff down the river system. This study provides a reference for basin-wide land use and urban planning as well as flood hazard mitigation.展开更多
基金the sample collections.This study was supported by the Key projects of Hunan Provincial Education Department(No.19A222)Hunan Provincial Natural Science Foundation(2018JJ3236)+1 种基金National Key Research and Development Program of China(No.2019YFD09006030)National Natural Science Foundation of China(No.31772832 and 31960254).
文摘With the population increasing,fish communities,as important components in the river system,were inescapably impacted by human activities.To investigate these impacts,we characterized the fish community’s composition by environmental DNA metabarcoding in the urban and suburban sites along Xiang River in central China.The results showed that 32 species were identified,and most species were from Cypriniform.The analysis indicated no significant differences in fish communities among the three urban areas.However,significant differences were observed between the bank solidified and non-solidified areas,which indicated that the channelization significantly influenced the biodiversity and abundances.An alien species,Clarias gariepinus,was discovered in all examined sites,and it was negatively associated with ten native species.Furthermore,human populations and acidification were also negatively related to diversity.Our findings clearly showed that the consequences of anthropogenic activities shaped ichthyofauna and caused biodiversity loss in the urban river.
基金supported by the Open Fund of State Key Laboratory of Remote Sensing Science(Grant No.OFSLRSS201720)the National Natural Science Foundation of China(Grant No.41401097+1 种基金 41771536)National Key Research and Development Program Project:Development of the Platform for Dynamic Early Warning and Risk Assessment of Mountain Torrents Disaster(2017YFC1502505)
文摘Booming urbanization due to a fast-growing population results in more impervious areas, less infiltration,and hence greater flood peak and runoff. Clear understanding of flood responses in regions with different levels and expansions of urbanization is of great importance for regional urban planning. In this study, comparison of flooding responses to urbanization processes in terms of flood peak and runoff volume in the upper, middle,and lower Xiang River Basin(XRB), China, was carried out using the Hydrologic Engineering Center-Hydrologic Modeling System(HEC-HMS) model. From 2005 to 2015, urbanization level and intensity were higher in the lower XRB compared to the upper and middle XRB, and the overall expansion rate of urban areas was 112.8%.Modeling results by the HEC-HMS model indicate elevated flood peak discharges and volumes due to fast urbanization in the XRB from the 1980 s to 2015. This rapid increase is particularly the case in the lower XRB. The study also revealed different hydrological responses of flood regimes—urbanization tends to have larger impacts on peak flood flow rather than on flood volume in the lowerXRB, which further corroborated urbanization-induced intensifying flood processes in terms of peak flood flow.Urbanization has increasing impacts on flood volume from the upper to the lower XRB, which can be attributed to accumulated runoff down the river system. This study provides a reference for basin-wide land use and urban planning as well as flood hazard mitigation.
文摘采用高效液相色谱质谱法分析了湘江长沙河段水体及底泥中4种常见四环素类抗生素的含量特征及其季节变化,并采用实时荧光定量 PCR 研究了该水域相应的5种代表性抗生素抗性基因（tet A,tet C,tet G,tet M 和 tet X）的存在及丰度.结果表明,水体中四环素类抗生素的质量浓度均值在16.23~496.73 ng·L^-1之间,底泥中四环素类抗生素的质量分数为347.77~3829.75 ng·kg^-1,易受季节变化影响.5种目标抗性基因在所有样品中均有检出,其中 tet A 和 tet C 的绝对拷贝数及相对丰度较高,为湘江长沙河段的优势抗性基因.相关性分析表明：冬季水体中的 tet A 和 tet C 含量与底泥中的含量显著相关,几种目标抗生素与抗性基因之间并不存在明显线性关系.
