Presentation Title

Annual Precipitation Influences Denitrification Potential in Portland’s Urban Green Stormwater Infrastructure

Start Date

5-2-2018 3:30 PM

End Date

5-2-2018 3:40 PM

Abstract

Urban areas are challenged with developing management solutions to mitigate the effects of urban stormwater. Municipalities across the US are adopting green stormwater infrastructure (GSI) to manage urban runoff due to its potential environmental and economic advantages over conventional “gray” infrastructure. GSI is designed to emulate natural hydrologic and ecological functions by infiltrating, filtering, storing, detaining, and evaporating local runoff and retaining and transforming contaminants through biogeochemical processes. However, GSI ecosystems are unlike their natural analogs in many ways: they are isolated in the environment, experience more frequent and intense flooding events, and receive supplies of organic and inorganic pollutants in urban runoff. Little is known about the ecological processes in GSI that are intended to provide environmental benefits and how these processes vary across seasons and differences in annual precipitation. This study investigates potential nitrogen removal through denitrification [as denitrification enzyme activity (DEA)] in bioswale-type GSI during a dry year (2015) and a wet year (2016) in Portland, OR. Preliminary results show seasonal and annual differences in DEA response. DEA was higher during the winters than summers and was higher in the wet year (2016) than the dry year (2015). Additionally, results show differing relationships between soil infiltration rates and DEA. Slow-infiltrating soils showed higher rates of DEA than fast-infiltrating soils. Further analyses will explore the extent to which soil physiochemistry influences potential nitrogen removal in Portland GSI.

Subjects

Land/watershed management, Soil science, Water quality

Persistent Identifier

https://archives.pdx.edu/ds/psu/25650

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Feb 5th, 3:30 PM Feb 5th, 3:40 PM

Annual Precipitation Influences Denitrification Potential in Portland’s Urban Green Stormwater Infrastructure

Urban areas are challenged with developing management solutions to mitigate the effects of urban stormwater. Municipalities across the US are adopting green stormwater infrastructure (GSI) to manage urban runoff due to its potential environmental and economic advantages over conventional “gray” infrastructure. GSI is designed to emulate natural hydrologic and ecological functions by infiltrating, filtering, storing, detaining, and evaporating local runoff and retaining and transforming contaminants through biogeochemical processes. However, GSI ecosystems are unlike their natural analogs in many ways: they are isolated in the environment, experience more frequent and intense flooding events, and receive supplies of organic and inorganic pollutants in urban runoff. Little is known about the ecological processes in GSI that are intended to provide environmental benefits and how these processes vary across seasons and differences in annual precipitation. This study investigates potential nitrogen removal through denitrification [as denitrification enzyme activity (DEA)] in bioswale-type GSI during a dry year (2015) and a wet year (2016) in Portland, OR. Preliminary results show seasonal and annual differences in DEA response. DEA was higher during the winters than summers and was higher in the wet year (2016) than the dry year (2015). Additionally, results show differing relationships between soil infiltration rates and DEA. Slow-infiltrating soils showed higher rates of DEA than fast-infiltrating soils. Further analyses will explore the extent to which soil physiochemistry influences potential nitrogen removal in Portland GSI.