TY - JOUR
T1 - Baseflow nitrate in relation to stream order and agricultural land use
AU - Kang, Shujiang
AU - Lin, Henry
AU - Gburek, William J.
AU - Folmar, Gordon J.
AU - Lowery, Birl
PY - 2008/5
Y1 - 2008/5
N2 - Management of agricultural nonpoint-source pollution continues to be a challenge because of spatial and temporal variability. Using stream order as an index, we explored the distribution of nitrate concentration and load along the stream network of a large agricultural watershed in Pennsylvania - the East Mahantango Creek Watershed and two of its subwatersheds. To understand nitrate concentration variation in the stream water contributed from ground water, this study focused on baseflow. Impacts of agricultural land use area on baseflow nitrate in the stream network were investigated. Nitrate concentration showed a general decreasing trend with increasing stream order based on stream order averaged values; however, considerable spatial and temporal variability existed within each snapshot sampling. Nitrate loads increased with stream order in a power function because of the dominant effect of stream flow rate over ihe nitrate concentration. Within delineated subwatersheds based on stream orders, positive linear functions were found between agricultural land use area percentage and the baseflow nitrate concentration and between agricultural drainage area and the nitrate load. The slope of the positive linear regression between the baseflow nitrate concentration and percent agricultural land area seems to be a valuable indicator of a watershed s water quality as influenced by agricultural practices, watershed size, and specific physiographic setting. Stream order seems to integtate, to a certain degree, the source and transport aspects of nonpoint-source pollution on a yearly averaged basis and thus might provide a quick estimate of the overall trend in baseflow nitrate concentration and load distribution along complex stream networks in agricultural watersheds.
AB - Management of agricultural nonpoint-source pollution continues to be a challenge because of spatial and temporal variability. Using stream order as an index, we explored the distribution of nitrate concentration and load along the stream network of a large agricultural watershed in Pennsylvania - the East Mahantango Creek Watershed and two of its subwatersheds. To understand nitrate concentration variation in the stream water contributed from ground water, this study focused on baseflow. Impacts of agricultural land use area on baseflow nitrate in the stream network were investigated. Nitrate concentration showed a general decreasing trend with increasing stream order based on stream order averaged values; however, considerable spatial and temporal variability existed within each snapshot sampling. Nitrate loads increased with stream order in a power function because of the dominant effect of stream flow rate over ihe nitrate concentration. Within delineated subwatersheds based on stream orders, positive linear functions were found between agricultural land use area percentage and the baseflow nitrate concentration and between agricultural drainage area and the nitrate load. The slope of the positive linear regression between the baseflow nitrate concentration and percent agricultural land area seems to be a valuable indicator of a watershed s water quality as influenced by agricultural practices, watershed size, and specific physiographic setting. Stream order seems to integtate, to a certain degree, the source and transport aspects of nonpoint-source pollution on a yearly averaged basis and thus might provide a quick estimate of the overall trend in baseflow nitrate concentration and load distribution along complex stream networks in agricultural watersheds.
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U2 - 10.2134/jeq2007.0011
DO - 10.2134/jeq2007.0011
M3 - Article
C2 - 18453401
AN - SCOPUS:43749118767
SN - 0047-2425
VL - 37
SP - 808
EP - 816
JO - Journal of Environmental Quality
JF - Journal of Environmental Quality
IS - 3
ER -