Name
Examining Bioavailable Heavy Metals across Urban Riparian Zone Sediments of Southern Ontario
Description
Defined as areas of aquatic-terrestrial-ecotones, riparian zone gradients contain niche biologic, chemical, and physical properties. Usually focused on in a rural context, bioavailable forms of Heavy Metals (i.e., Cd, Cr, Cu, Ni, Pb, Zn) sourced from urban areas can accumulate over time and exceed thresholds of toxicity within riparian soil, having the potential to directly impact aquatic and terrestrial life. Depending on the location of riparian zones, their physiographic settings differ with dominant types of sediment, landforms, and influx of metals. This study aims to capture the influence of setting and measured environmental components (pH, soil organic matter %, gravimetric moisture content %, sand-silt-clay composition) on heavy metal accumulation within urban riparian zones across Southern Ontario over the 2022 growing season. Soils were sampled from 48 urban riparian zones, across 8 differing physiographic regions of Southern Ontario. Surficial soil measurements were taken at the beginning and end of the 2022 growing season from near-stream and field-edge areas of each riparian zone. Soils were additionally sampled from “non-urbanized” land in each physiographic region, providing background values per area. Whether concentrations measured were higher near the stream or along the field edge of the riparian zone differed with each heavy metal, as Ni and Pb occurred in higher concentrations along the field edge, while Cu, Cd, and Zn measured higher near stream. Varying measurements of heavy metals reflect the heterogenous physical factors of regions studied, determining if dominant soil type or proximity to anthropogenic areas are the key drivers of levels sampled.