Junior Award Winner
Hal Van Ryswyk
Bioswales are a type of permeable green infrastructure designed to slow storm water runoff, and clean runoff by sequestering pollutants such as heavy metals. The influence of bioswale features such as slope, terrain, soil type, depth, and vegetation on the efficacy of bioswales in processing storm water runoff is an active area of research aimed partly at optimizing bioswale design and construction. Concentrations of aluminum, cobalt, chromium, copper, iron, magnesium, manganese, nickel, lead, vanadium and zinc were measured in surface soil, depth soil, and at several plant locations. The distribution of metals in surface, depth, and rhizosphere soil fractions were measured to analyze the roles of location along the water flow axis, bioswale terrain, sampling depth, vegetation types, and soil chemistry on the distribution of metals. Soils were digested according to EPA Method 3051 and for soil fractions, a modified Tessier et. al. (1979) sequential extraction protocol, and metal concentrations were quantified using ICP-OES. Orientation of the bioswale to water flow axis, slope and linear length are predictors of runoff metal concentrations. Bioswale vegetation needs to be selected in accordance with bioswale conditions but also metal absorption ability to further clean stormwater runoff. Trees appear superior to rocks and sedge at sequestering metals in soil. The bioswale decreases the concentration of metals in water infiltrating into underground aquifers.
Evans, Zachary, "Spatial Distribution of Sequestered Metals in an Arid Southern California Bioswale" (2017). 2017 Claremont Colleges Library Undergraduate Research Award. 4.