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Dredging of Drainage Ditches Increases Short‐Term Transport of Soluble Phosphorus
Author(s) -
Smith Douglas R.,
Warnemuende E. A.,
Haggard B. E.,
Huang C.
Publication year - 2006
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2005.0301
Subject(s) - dredging , ditch , drainage , phosphorus , environmental science , sediment , water column , desorption , hydrology (agriculture) , environmental engineering , adsorption , environmental chemistry , geology , chemistry , geotechnical engineering , oceanography , ecology , paleontology , organic chemistry , biology
Managed drainage ditches are common in the midwestern United States. These ditches are designed to remove water from fields as quickly as possible, and sediment buildup necessitates dredging, to ensure adequate water removal. This laboratory study was conducted to determine the impact of ditch dredging on soluble phosphorus (P) transport. Ditch sediments were collected from a drainage ditch in northeastern Indiana immediately before and after dredging. The sediments were placed in a stream simulator, and stream water was loaded with 0.55 m M P for 5 d (adsorption experiment). Water was then removed, and “clean” water (no P added) was used for a desorption experiment, lasting 1 d. During the adsorption experiment, pre‐dredged sediments were able to remove P from the water column quicker, and P concentrations 120 h after introduction of high P water were lower for the pre‐dredged sediments (0.075 m M P) than the dredged sediments (0.111 m M P). During the desorption experiment, P was released to the water column slower in the pre‐dredged treatment than the dredged treatment (instantaneous flux at t = 0 was 0.205 μ M P h −1 for pre‐dredged and 0.488 μ M P h −1 for dredged). This occurred despite higher Mehlich 3–extractable P in the pre‐dredged sediments than the dredged sediments. Equilibrium phosphorus concentrations (EPC o ) were lower in the pre‐dredged sediments during both adsorption and desorption experiments. Transport of soluble P immediately after dredging will likely increase in drainage ditches; however, dredging is a necessary management tool to ensure adequate discharge of water from surrounding fields.