A. James Clark School of Engineering

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The collections in this community comprise faculty research works, as well as graduate theses and dissertations.

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Subject: search.filters.subject.Heavy metals

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    IMPACT OF PERIODIC HIGH CONCENTRATIONS OF SALTS ON BIORETENTION NUTRIENTS PERFORMANCE
    (2018) McManus, Meigan; Davis, Allen P; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Bioretention is a stormwater control measure commonly used to remove pollutants, including nitrogen (N) and phosphorus (P), from urban runoff. This project seeks to evaluate the impacts of high concentrations of sodium chloride (NaCl) deicer on bioretention N and P removal performances. Bioretention mesocosm studies were conducted to examine N and P removal efficiencies following periodic 2,000, 5,000, and 10,000 mg/L NaCl salt applications. Episodic washouts of TSS, N and P, likely due to ion exchange with the sodium and chloride ions, were observed for all three columns and mass export of P was observed for the 2,000 and 5,000 mg/L NaCl columns after 26 m and 7 m applied water, respectively. No mass N export was observed. Based on a mass balance of N and P, it is recommended to limit the use of deicers to prevent long-term P export.
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    Environmental Performance and Sustainability of Bioretention Cells
    (2009) Jones, Philip Sumner; Davis, Allen P; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Bioretention cells use vegetation and soil media for source control of urban stormwater runoff, alleviating waterway impairment. Environmental performance of two cells was investigated. First, a cell capturing road runoff was monitored for one year. At a second cell, media were sampled to measure lifetime metal accumulation and evaluate the environmental, health, and maintenance implications of metal sequestration. Monitoring found high metal and suspended solids removal, generally poor nutrient performance, and chloride export. Runoff volume and peak flow rate reduction occurred for small storm events. For larger events, outflow volume consistently exceeded inflow because of unique site conditions. Lead, copper, and zinc media concentrations in the second cell were elevated but well below cleanup thresholds. Metals were strongly bound to bioretention media and largely immobile; lead bioavailability was comparable to generic soil estimates. Most metal accumulation was near the inflow point in the top 3 to 12 cm of media.
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    DYNAMIC STUDY OF HEAVY METAL FATES IN BIORETENTION SYSTEMS
    (2004-08-12) sun, xueli; Davis, Allen P; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Bioretention is a best management practice (BMP). In this research, pot prototypes filled with bioretention media were built to simulate the conditions of natural growth of three grasses: Panicum virgatum, Kentucky-31 and Bromus ciliatus. Synthetic runoff was applied. The results show average removals of Zn, Cu, Pb and Cd exceed 90% by the bioretention media and the fates of input metals are 87.5-96.9% captured in soil media, 0.5-3.3% accumulated in plants and 2.0-11.6% not captured by bioretention media. Based on field biomass yields and laboratory metal concentrations in plants, it appears possible and practical to achieve removals of Zn, Cu, Pb and Cd of 20% by Panicum virgatum, 15% by Kentucky-31 and 10% by Bromus ciliatus, espectively. If 20% of input metals are accumulated by plants, the lifetime of a bioretention cell will be extended by 1.25 times.