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
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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.
