https://stacks.cdc.gov/view/cdc/37676/cdc_37676_DS1.pdf

Toxicological Profile for Lead

The low impact development (LID) approach has been recommended as an alternative to traditional stormwater design. Research on individual LID practices such as bioretention, pervious pavements, and grassed swales has increased in recent years. Bioretention cells have been effective in retaining large volumes of runoff and pollutants on site, and consistently reduced concentrations of certain pollutants such as metals. However, retention of certain pollutants such as nitrate–nitrogen and phosphorus has been problematic. Porous pavements have been extremely effective in infiltrating stormwater runoff. Concerns have been raised about groundwater contamination, but research has shown that this is not a problem in most settings. Green roofs have been found to retain a large percentage of rainfall (63% on average) in a variety of climates. A common thread across bioretention, green roofs and grassed swales was found: the export of phosphorus. The issue appears to be linked to high phosphorus levels in the soil media, or possibly to fertilization of turf or planted areas. Solutions to this problem have been recommended. Contrary to popular belief, research has shown that bioretention and pervious pavements continue to infiltrate even with frost in the ground. Although issues have been identified with retention of certain pollutants, the LID approach has been found to result in increased retention of stormwater and pollutants on site, mimicking pre-development hydrologic function. Future research needs have also been identified.

https://clear.uconn.edu/projects/tmdl/library/papers/dietz_2007.pdf

Low Impact Development Practices: A Review of Current Research and Recommendations for Future Directions

Characterization of heavy metal particles embedded in tire dust.

Urban green space is purported to offset greenhouse-gas (GHG) emissions, remove air and water pollutants, cool local climate, and improve public health. To use these services, municipalities have focused efforts on designing and implementing ecosystem-services-based “green infrastructure” in urban environments. In some cases the environmental benefits of this infrastructure have been well documented, but they are often unclear, unquantified, and/or outweighed by potential costs. Quantifying biogeochemical processes in urban green infrastructure can improve our understanding of urban ecosystem services and disservices (negative or unintended consequences) resulting from designed urban green spaces. Here we propose a framework to integrate biogeochemical processes into designing, implementing, and evaluating the net effectiveness of green infrastructure, and provide examples for GHG mitigation, stormwater runoff mitigation, and improvements in air quality and health.

https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.1890/090220

Coupling biogeochemical cycles in urban environments: ecosystem services, green solutions, and misconceptions

Bioretention, or variations such as bioinfiltration and rain gardens, has become one of the most frequently used storm-water management tools in urbanized watersheds. Incorporating both filtration and infiltration, initial research into bioretention has shown that these facilities substantially reduce runoff volumes and peak flows. Low impact development, which has a goal of modifying postdevel- opment hydrology to more closely mimic that of predevelopment, is a driver for the use of bioretention in many parts of the country. Research over the past decade has shown that bioretention effluent loads are low for suspended solids, nutrients, hydrocarbons, and heavy metals. Pollutant removal mechanisms include filtration, adsorption, and possibly biological treatment. Limited research suggests that bioretention can effectively manage other pollutants, such as pathogenic bacteria and thermal pollution, as well. Reductions in pollutant load result from the combination of concentration reduction and runoff volume attenuation, linking water quality and hydrologic perfor- mance. Nonetheless, many design questions persist for this practice, such as maximum pooling bowl depth, minimum fill media depth, fill media composition and configuration, underdrain configuration, pretreatment options, and vegetation selection. Moreover, the exact nature and impact of bioretention maintenance is still evolving, which will dictate long-term performance and life-cycle costs. Bioretention usage will grow as design guidance matures as a result of continued research and application.

Bioretention Technology: Overview of Current Practice and Future Needs

Loading estimates of lead, copper, cadmium, and zinc in urban runoff from specific sources

Urban stormwater runoff contains a broad range of pollutants that are transported to natural water systems A practice known as biological retention (bioretention) has been suggested to manage stormwater runoff from small, developed areas Bioretention facilities consist of porous soil, a topping layer of hardwood mulch, and a variety of different plant species A detailed study of the characteristics and performance of bioretention systems for the removal of several heavy metals (copper, lead, and zinc) and nutrients (phosphorus, total Kjeldahl nitrogen [TKN], ammonium, and nitrate) from a synthetic urban stormwater runoff was completed using batch and column adsorption studies along with pilot-scale laboratory systems The roles of the soil, mulch, and plants in the removal of heavy metals and nutrients were evaluated to estimate the treatment capacity of laboratory bioretention systems Reductions in concentrations of all metals were excellent (> 90%) with specific metal removals of 15 to 145 mg/m2 per event Moderate reductions of TKN, ammonium, and phosphorus levels were found (60 to 80%) Little nitrate was removed, and nitrate production was noted in several cases The importance of the mulch layer in metal removal was identified Overall results support the use of bioretention as a stormwater best management practice and indicate the need for further research and development

Laboratory study of biological retention for urban stormwater management.

High nutrient inputs and eutrophication continue to be one of the highest priority water quality problems. Bioretention is a low-impact development technology that has been advocated for use in urban and other developed areas. This work provides an in-depth analysis on removal of nutrients from a synthetic stormwater runoff by bioretention. Results have indicated good removal of phosphorus (70 to 85%) and total Kjeldahl nitrogen (55 to 65%). Nitrate reduction was poor (< 20%) and, in several cases, nitrate production was noted. Variations in flowrate (intensity) and duration had a moderate affect on nutrient removal. Mass balances demonstrate the importance of water attenuation in the facility in reducing mass nutrient loads. Captured nitrogen can be converted to nitrate between storm events and subsequently washed from the system. Analysis on the fate of nutrients in bioretention suggests that accumulation of phosphorus and nitrogen may be controlled by carefully managing growing and harvesting of vegetation.

https://www.jstor.org/stable/info/25045975

Water Quality Improvement through Bioretention Media: Nitrogen and Phosphorus Removal

Intensive automobile use, weathering of building materials, and atmospheric deposition contribute lead, copper, zinc, and other heavy metals to urban and roadway runoff. Bioretention is a low-impact-development best management practice that has the potential to improve stormwater quality from developed areas. The practice represents a soil, sand, organic matter, and vegetation-based storage and infiltration facility used in parking lots and on individual lots to treat runoff. Investigations using pilot-plant laboratory bioretention systems and two existing bioretention facilities documented their effectiveness at removing low levels of lead, copper, and zinc from synthetic stormwater runoff. Removal rates of these metals (based on concentration and total mass) were excellent, reaching close to 100% for all metals under most conditions, with effluent copper and lead levels mostly less than 5 microg/L and zinc less than 25 microg/L. Somewhat less removal was noted for shallow bioretention depths. Runoff pH, duration, intensity, and pollutant concentrations were varied, and all had minimal effect on removal. The two field investigations generally supported the laboratory studies. Overall, excellent removal of dissolved heavy metals can be expected through bioretention infiltration. Although the accumulation of metals is a concern, buildup problems are not anticipated for more than 15 years because of the low metal concentrations expected in runoff.

Water quality improvement through bioretention: lead, copper, and zinc removal.

The washing of cadmium (from CdO(s)) from a soil column employing either an acid solution or EDTA (a strong metal chelator) was examined. For Cd(II) levels of 50 to 1000 mg/kg, the fraction removed was essentially independent of the initial Cd(II) concentration. The most efficient washing of cadmium was achieved using an acid wash solution at pH 2.5. Lower Cd(II) removals were found at lower pH, apparently due to inhibition of CdO(s) dissolution by constituents released from the soil under highly acidic conditions. EDTA wash solutions were employed at EDTA:cadmium molar ratios ranging from 1:1 to 10:1. Up to 90% removal of total Cd(II) was achieved at the 10:1 ratio after the passage of the first 50 PV of wash solution. Although higher chelate levels enhanced Cd(II) removal, the utilization efficiency of EDTA for cadmium decreased.

Mohammad Shokouhian

Papers

Loading estimates of lead, copper, cadmium, and zinc in urban runoff from specific sources

Laboratory study of biological retention for urban stormwater management.

Water Quality Improvement through Bioretention Media: Nitrogen and Phosphorus Removal

Water quality improvement through bioretention: lead, copper, and zinc removal.

Washing of Cadmium(II) from a Contaminated Soil Column