Ecological risk assessment of trace elements accumulated in stormwater ponds within industrial areas

Stormwater ponds can provide flood protection and efficiently treat stormwater using sedimentation. As the ponds also host aquatic biota and attract wildlife, there is a growing concern that the sediment bound pollutants negatively affect aquatic organisms and the surrounding ecosystem. In this study, we used three methods to assess the accumulation and the potential ecological risk of 13 different heavy metals and metalloids (e.g. trace elements) including both elements that are frequently monitored and some which are rarely monitored in sediment from 5 stormwater ponds located within catchments with predominately industrial activities. Ecological risk for organisms in the older ponds was observed for both commonly (e.g. Cd, Cu, Zn) and seldom (e.g. Ag, Sb) monitored trace elements. The 3 methods ranked the degree of contamination similarly. We show that methods usually used for sediment quality assessment in aquatic ecosystems can also be used for screening the potential risk of other trace elements in stormwater ponds and may consequently be useful in stormwater monitoring and management. Our study also highlights the importance of establishing background conditions when conducting ecological risk assessment of sediment in stormwater ponds.

Environmental assessment of stormwater pond impacts on a Rouge River tributary

This study was conducted to evaluate impacts of stormwater ponds in the Municipality of the Town of Richmond Hill on select physical (temperature, dissolved oxygen, and pH) chemical (nutrients) and biological (macroinvertebrate community, macrophyte and experimental Hyalella azteca and Daphnia magna enclosures) aspects of a Rouge River tributary. Over a five-month period five sites along the tributary close to the outfall of the stormwater ponds were sampled to determine if there were any impacts, cumulatively (with increasing number of pond outfalls along the tributary) and locally (above and below an outfall). Physical and nutrient parameters showed no signifiant degradation in water quality, either cumulatively or locally. Macrophytic data showed some decrease in biomass at downstream sites, but no decrease in diversity or species richness. Survivorship in the enclosures containing Hyalella azteca and Daphnia magna showed no significant cumulative change. Analysis of the macroinvertebrate community showed no cumulative or local impact until the farthest downstream site.

Environmental assessment of stormwater pond impacts on a Rouge River tributary

This study was conducted to evaluate impacts of stormwater ponds in the Municipality of the Town of Richmond Hill on select physical (temperature, dissolved oxygen, and pH) chemical (nutrients) and biological (macroinvertebrate community, macrophyte and experimental Hyalella azteca and Daphnia magna enclosures) aspects of a Rouge River tributary. Over a five-month period five sites along the tributary close to the outfall of the stormwater ponds were sampled to determine if there were any impacts, cumulatively (with increasing number of pond outfalls along the tributary) and locally (above and below an outfall). Physical and nutrient parameters showed no signifiant degradation in water quality, either cumulatively or locally. Macrophytic data showed some decrease in biomass at downstream sites, but no decrease in diversity or species richness. Survivorship in the enclosures containing Hyalella azteca and Daphnia magna showed no significant cumulative change. Analysis of the macroinvertebrate community showed no cumulative or local impact until the farthest downstream site.