Submitted to: Ecological Engineering
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/3/2011
Publication Date: 7/15/2011
Citation: Williams, C.F., Nelson, S.D. 2011. Comparison of rhodamine-WT and bromide as a tracer for elucidating internal wetland flow dynamics. Ecological Engineering. 37:1492-1498. Interpretive Summary: Artificially constructed wetlands offer a low cost treatment alternative to remove a number of pollutants found in effluent water from industry, mining, agriculture, and urban areas. To better understand the internal hydrology and biogeochemical processes operating within wetlands a method to identify and track individual parcels of water is needed. Bromide is usually used as a conservative tracer within wetlands but has higher costs associated with it due to increased analytical costs. A new method for tracking water through wetlands using the fluorescent dye Rhodamine-WT is proposed and compared to bromide. Rhodamine-WT was found to be a cheaper alternative to tracking individual parcels of water through treatment wetlands.
Technical Abstract: Artificially constructed wetlands offer a low cost treatment alternative to remove a number of pollutants found in effluent water from industry, mining, agriculture, and urban areas. The determination of treatment efficiency cannot be determined without understanding the flow dynamics of individual parcels of water through the wetland. A method for tracking parcels of water is proposed using Rhodamine-WT as a tracer. A series of tracer tests were conducted on a 1.2 ha treatment wetland. Bromide and Rhodamine-WT were simultaneously dosed into the inlet and monitored at 60 sampling locations for 5 weeks. Rhodamine-WT concentrations were found to be coincident with bromide. For all three events the relationship between Rhodamine-WT and bromide was linear with a slope of 0.82. The peak concentration of Rhodamine-WT and bromide were also found to coincide throughout the wetland. Rhodamine-WT can be used to determine the movement of individual parcels of water through a treatment wetland and used to determine treatment efficiencies at individual locations within a wetland.