Seasonal drivers of chemical and hydrological patterns in roadside infiltration-based green infrastructure

Angela R Mullins; Daniel J Bain; Erin Pfeil-McCullough; Kristina G Hopkins; Sarah Lavin; Erin Copeland

doi:10.1016/j.scitotenv.2020.136503

Seasonal drivers of chemical and hydrological patterns in roadside infiltration-based green infrastructure

Sci Total Environ. 2020 Apr 20:714:136503. doi: 10.1016/j.scitotenv.2020.136503. Epub 2020 Jan 10.

Authors

Angela R Mullins¹, Daniel J Bain², Erin Pfeil-McCullough², Kristina G Hopkins³, Sarah Lavin⁴, Erin Copeland⁵

Affiliations

¹ Department of Geology and Environmental Science, University of Pittsburgh, Pittsburgh, PA 15260, USA. Electronic address: arm175@pitt.edu.
² Department of Geology and Environmental Science, University of Pittsburgh, Pittsburgh, PA 15260, USA.
³ U.S. Geological Survey, South Atlantic Water Science Center, Raleigh, NC 27607, USA.
⁴ Rhea Engineers & Consultants, Inc., Valencia, PA 16059, USA.
⁵ Pittsburgh Parks Conservancy, Pittsburgh, PA 15203, USA.

PMID: 32018946
DOI: 10.1016/j.scitotenv.2020.136503

Abstract

Infiltration-based green infrastructure has become a popular means of reducing stormwater hazards in urban areas. However, the long-term effects of green infrastructure on the geochemistry of roadside environments are poorly defined, particularly given the considerable roadside legacy metal contamination from historic industrial activity and vehicle emissions (e.g., Pb). Most current research on green infrastructure geochemistry is restricted to time periods of less than a year or limited sets of chemical species. This further limits our understanding of systems that evolve over time and are subject to seasonal variability. Between 2016 and 2018, two infiltration trenches in Pittsburgh, PA, were monitored to determine infiltration rates and dissolved nutrient and metal content. The trench water was analyzed to characterize seasonal patterns in both trench function and chemistry. Shifting patterns in infiltration rate and geochemical activity show trends corresponding with seasonal changes. Trench function is dependent on the local water table, with the highest infiltration rates occurring when evapotranspiration is active and groundwater elevation is low. Two seasonal chemical patterns were identified. The first is driven by road salt application in the winter and interaction of the salt pulse increase Pb and Cu concentrations. The second is driven by the formation of summer reducing environments that increase dissolved Fe and Mn. These findings suggest that chemical and hydrological activity in infiltration-based green infrastructure varies seasonally and may remobilize legacy contamination.

Keywords: Contamination; Green infrastructure; Infiltration; Legacy; Road salt; Stormwater.