Environmental assessment of Lake Gibson sediments, water quality, and soils of the Niagara Region

Abstract

In light of the fact that literature on toxicity of heavy metals in non-acidified freshwater systems is sparse, this project was initiated to conduct an environmental assessment of Lake Gibson. Chemistry of soils from adjacent areas and vineyards in the region provide a comparative background database. Water quality determinations were used to identify and highlight areas of environmental concern within the Lake Gibson watershed. A Shelby Corer was used to obtain 66 sediment cores from Lake Gibson. These were sectioned according to lithology and color to yield 298 samples. A suite of 122 soil samples was collected in the region and vicinity of Lake Gibson. All were tested for metals and some for Total Petroleum Hydrocarbons (TPH). Evaluation of the results leads to the following conclusions: 1. Metal concentrations ofAI, Cd, Cu, Cr, Pb, Ni, Fe and Zn in soils from the Niagara Region are well below background limits set by the Ministry of the Environment and Energy (MOEE) for provincial soils. 2. There is a spatial and depth difference for some of the metals within the various soils. The Cr, Ni and Pb contents of soils vary throughout the region (p<O.05). In addition, Pb contents tend to be highest in surficial soil samples (p<O.05), an observation consistent with deposition by airborne particulates. 3. The Ni contents of sediments from Lake Gibson fall below the LEL (Lower Effect Level) guideline specified by the MOEE for aquatic ecosystems. 4. All other metal contents exceed the LEL, and in some instances they also exceed the SEL (Severe Effect Level) guideline. In this instance acute toxicity testing of 11 the sediments is required to assess impact on the aquatic biota. 5. Specifically, effluents and discharges from outfalls, roadways, railways and industrial activities are all degrading the local ecosystem. 6. Mineral oil and greases are a major environmental concern in the sediments of Lake Gibson. Ofthe 240 samples tested for TPH, 200 samples exceed the MOEE Open Water Disposal Guideline of 1,500 mg/kg. 7. Four areas within Lake Gibson are especially degraded with respect to TPH. One area is just downstream from the Old WeIland Canal divergence point and waterfall. Other areas of concern are located just south of Beaverdams Road and just west ofthe Ontario Hydro control pipes; south ofthe Village ofBeaverdams. The fourth area of environmental concern and TPH impact is located between Highway 406 and Merrittville Highway.