Microtopographic modification conserves urban wetland water quality by increasing the dissolved oxygen in the wet season  

作　　者：Yali Liu Jianqing Du Panpan Hu Mingzhu Ma Dan Hu 

机构地区：[1]State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Enuironmental Sciences,Chinese Academy of Sciences,Beijing 100085,China [2]University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Journal of Environmental Sciences》2020年第1期71-81,共11页环境科学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(No.41571482);the State Key Laboratory of Urban&Regional Ecology(No.SKLURE2017-1-1)

摘　　要：Microtopography affects hydrological processes and forms different microhabitats.Our previous study uncovered that riparian zone microtopography created various microhabitats with different soil environments and runoff-infiltration patterns.However,how riparian microtopography and microtopography within the water area(waterfall and tributary)affects downstream water quality remains unclear.Therefore,water samples were taken almost monthly in both the main stream and the tributary,before and after waterfalls,and near the bottom of three microtopographic types from June 2016 to March 2017.Compared with the dry season,the fact that water quality worsened in the wet season and that there were positive correlations for nitrate(NO3-)between water and the corresponding soil samples suggested that the riparian-soil environment affected the adjacent water quality mainly in the wet season.Nevertheless,riparian microtopography did not influence water quality downstream because of the low rainfall frequency and the weak leaching process due to plant interception.In the wet season,both the tributary and the waterfall increased the dissolved oxygen in the water body and,therefore,lowered the risk of eutrophication.The tributary has two pathways for improving the water quality,by increased disturbance and flow velocity,while the waterfall only has the former.However,such effects were not significant in the dry season.We conclude that the application of microtopographic modification is useful in maintaining urban wetland water quality in wet seasons.Microtopography affects hydrological processes and forms different microhabitats.Our previous study uncovered that riparian zone microtopography created various microhabitats with different soil environments and runoff-infiltration patterns.However,how riparian microtopography and microtopography within the water area（waterfall and tributary） affects downstream water quality remains unclear.Therefore,water samples were taken almost monthly in both the main stream and the tributary,before and after waterfalls,and near the bottom of three microtopographic types from June 2016 to March 2017.Compared with the dry season,the fact that water quality worsened in the wet season and that there were positive correlations for nitrate（NO3-） between water and the corresponding soil samples suggested that the riparian-soil environment affected the adjacent water quality mainly in the wet season.Nevertheless,riparian microtopography did not influence water quality downstream because of the low rainfall frequency and the weak leaching process due to plant interception.In the wet season,both the tributary and the waterfall increased the dissolved oxygen in the water body and,therefore,lowered the risk of eutrophication.The tributary has two pathways for improving the water quality,by increased disturbance and flow velocity,while the waterfall only has the former.However,such effects were not significant in the dry season.We conclude that the application of microtopographic modification is useful in maintaining urban wetland water quality in wet seasons.

关 键 词：Microtopographic modification Wetland water quality TRIBUTARY WATERFALL EUTROPHICATION 

分 类 号：X52[环境科学与工程—环境工程]