Water Resources Research Act Program

Details for Project ID 2012ND254B

Tile drain water: identification of sources and quality improvement by a constructed wetland

Institute: North Dakota
Year Established: 2012 Start Date: 2012-03-01 End Date: 2013-02-28
Total Federal Funds: $10,375 Total Non-Federal Funds: $20,750

Principal Investigators: Marinus Otte

Abstract: The surface area of fields being tile drained in North Dakota has been and still is rapidly growing, particularly to alleviate soil salinity. Apart from the effects this may have on the local and regional hydrology there is concern about the high concentrations of sulfate, particularly because of its role in so-called secondary or internal eutrophication. This refers to the binding of sulfate, and particularly its reduction product sulfide, to sediments while competing with phosphate, thus mobilizing the latter into the water column. Through this indirect effect increased sulfate loading from North Dakotan soils into the Missouri and Red River watersheds therefore contributes to increased phosphate loading, in turn exacerbating the dead zones in Lake Winnipeg and the Gulf of Mexico. In order to fully address this issue knowledge is required about (1) the sources of sulfate in tile drain water, so that actions may be identified to reduce the levels of sulfate in tile drain water, and about (2) methods that are affordable for land owners to lower sulfate and phosphate loading into surface waters. Sources of sulfate in tile drain water include precipitation, run-off, surface water and groundwater. The contribution of each of these is not easily quantified but needs to be assessed in order to manage sources and to provide more guidance for the installation of tile drains. Removal of sulfate from water is not easy either but is possible through the reduction of sulfate to sulfide in anaerobic soils. This approach has been successfully used in constructed wetlands, and has the added advantage of providing ecosystem services such as wildlife habitat. Other benefits are that constructed wetlands may also count as credits towards wetland mitigation, and may be combined with biomass production for fuel. Objectives are: 1.Create a database of the element composition (about 50 elements, including P and S) of surface, pore and ground waters at the Embden Discovery Farm over the 2012 field season. 2.Assess the feasibility of using multi-element fingerprinting to identify and quantify the sources of tile drain water. 3.Calculate a mass balance for multiple elements including P and S from the sources of the tile drain water to the outlet of the constructed wetland. 4.Assess the efficacy of the constructed wetland in removing S and P from tile drain water.