Phosphorus Cycling and Effects of Chloride in Subsurface Gravel Wetlands Used to Manage Urban Stormwater Runoff

Marcos Kubow

University of Vermont

Co-Authors: E. Roy, D. Rizzo, A. Torizzo

Phosphorus (P) is a limiting nutrient in freshwater systems, including Lake Champlain. P continues to be considered a top constituent of concern due to eutrophication. The plurality of P runoff entering the lake from Vermont comes from agriculture, however, urban systems contribute more P per acre. The focus of this study is to increase stormwater filtration with green stormwater infrastructure (GSI), decreasing P loads to downstream waters. Subsurface horizontal-flow gravel wetlands are increasingly being installed in the region for this purpose. While numerous studies have investigated similar systems for wastewater treatment, information is lacking on their P removal performance in the context of GSI. Additionally, the effects of chloride (from deicing salt) on gravel wetland performance remain poorly understood. The main concerns of chloride are the effect on wetland biology (namely plants) and potential clogging. We aim to fill these knowledge gaps by testing a number of locally sourced gravels and fabricated “wetland muck” materials to determine their effects on P dynamics when included in gravel wetland GSI designs. Furthermore, local native wetland plants will be used in a greenhouse bioassay to determine the individual species chloride tolerance. Results from our study will inform future stormwater SGW design in Vermont and elsewhere, including guidance on the specifications for materials used.

Please post comments and questions for the author below.

One thought on “Phosphorus Cycling and Effects of Chloride in Subsurface Gravel Wetlands Used to Manage Urban Stormwater Runoff

  1. Hi Marcos, nice project! Ironically, I populated this site with your files, but now that I am trying to watch the entire video, my internet connection is failing me. So, my questions are purely from reading the abstract and viewing the jpeg. I’m curious how you will quantify plant health in your greenhouse study, and if plants will be included in the column study. I don’t see a reference to plants in the column figures, but wanted to confirm. Also curious about the duration of the column study and rate of flow/disturbance events. Thanks!

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