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Role of Suspended Sediment in Irrigation Return Flow Chemistry, Southern Alberta
Author(s) -
Joseph Helen C.,
Ongley Edwin D.
Publication year - 1986
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr022i005p00643
Subject(s) - sediment , return flow , environmental science , hydrology (agriculture) , phosphorus , irrigation , pollutant , sediment transport , suspended solids , water quality , total suspended solids , environmental engineering , ecology , wastewater , geology , flow (mathematics) , chemical oxygen demand , chemistry , paleontology , geometry , mathematics , geotechnical engineering , organic chemistry , biology
Chemical impact of irrigation return flows upon receiving waters has historically focussed on salt and sediment production. Transport of other agricultural pollutants which are preferentially associated with suspended sediment is largely unknown in western Canada and poorly addressed elsewhere because of the traditional emphasis upon whole and filtered water chemistry. This study examines the role of suspended sediment in the flux of phosphorus and metals from large‐scale irrigation in semiarid southern Alberta. It establishes temporal patterns of chemical flux over the irrigation season, identifies the chemical species of phosphorus and metals, and assesses the potential for phosphorus and heavy metal impact from irrigation return flows upon receiving riverine systems. Whole and filtered water chemistry is found to be not especially useful in determining either chemical enrichment of return flows nor for evaluating impact upon receiving waters. Suspended sediment plays a major role in transport of phosphorus and heavy metals. Evidence from parent materials, prairie soils, chemical speciation, statistical relationships for metals and for phosphorus, and comparative data for suspended sediment during spring high flow in receiving rivers when sediments originate from eroding diffuse sources, all indicate that sediment‐associated phosphorus and metals in irrigation return flows are not anthropogenically enriched and do not represent an impact beyond that which is naturally occurring in receiving rivers.