Observation of bioturbation and hyporheic flux in streambeds  

作　　者：Jinxi SONG Xunhong CHEN Cheng CHENG 

机构地区：[1]College of Urban and Environmental Sciences,Northwest University,Xi'an 710127,China [2]School of Natural Resources,University of Nebraska-Lincoln,Lincoln,NE 68583-0996,USA [3]School of Environmental Science and Engineering,Chang’an University,Xi’an 710054,China

出　　处：《Frontiers of Environmental Science & Engineering》2010年第3期340-348,共9页环境科学与工程前沿（英文）

基　　金：the Program for Changjiang Scholars and Innovative Research Team of China Ministry of Education(No.IRT0811).

摘　　要：In the Elkhorn River,burrows,tubes,and sediment mounds created by invertebrate bioturbation were observed in the exposed streambed and commonly concentrated on the fine-sediment patches,which consist of silt,clay,and organic matter.These invertebrate activities could loosen the thin layer of clogging sediments and result in an increase of pore size in the sediments,leading to greater vertical hydraulic conductivity of the streambed(Kv).The measurements of the vertical hydraulic gradient across the submerged streambed show that vertical flux in the hyporheic zone can alter directions(upward versus downward)for two locations only a few meters apart.In situ permeameter tests show that streambed Kv in the upper sediment layer is much higher than that in the lower sediment layer,and the calculated Kv in the submerged streambed is consistently greater than that in the clogged sediments around the shorelines of the sand bars.Moreover,a phenomenon of gas bubble release at the water-sediment interface from the subsurface sediments was observed in the groundwater seepage zone where flow velocity is extremely small.The bursting of gas bubbles can potentially break the thin clogging layer of sediments and enhance the vertical hydraulic conductivity of the streambed.

关 键 词：invertebrate bioturbation CLOGGING hyporheic exchange STREAMBED the Elkhorn River 

分 类 号：TV1[水利工程]