Jesse Lake’s unpleasant smell concerning to residents.
LICA (Lakeland Industry and Community Association) uses its Portable Air Monitoring System (PAMS) to collect data on air quality in areas where LICA does not have any permanent monitoring stations. LICA also deploys the PAMS for a variety of reasons including but not limited to collecting data to understand specific local air quality questions based on community input or concerns, filling in gaps on our regional map of air pollutant concentrations, and collecting information in areas away from residents or industry to quantify background concentrations. In 2016, we deployed the PAMS in Bonnyville for three reasons: to fill in a gap, measure air quality in this important population center, and to shed light on a local issue residents talk about – the “unpleasant smell from Jessie Lake.”
This is LICA’s first set of measurements in the area, and so our observations should be considered preliminary. Additional study of this area will be required to better understand air quality behavior in the Bonnyville area however, we have some interesting initial results to share. Overall, concentrations of the air pollutants we measured were comparable to those observed in Cold Lake, and air quality was good in all parameters except one – “the smell”. We recorded an unusually high number of exceedances of the Alberta Ambient Air Quality Objective for hydrogen sulphide (H2S). Over 120 exceedances were recorded between June and October. The Objective for H2S is rarely exceeded, even in larger cities or areas dominated by heavy industry, so these observations can be considered unusual.
LICA’s monitoring data show that during the summer months, we routinely measured H2S concentrations above the 1-hour Alberta Ambient Air Quality Objective (AAAQO) of 10 parts per billion (ppb). While concentrations may have been above 10 ppb, the AAAQO is based on on odour nuisance potential. This means that above 10 ppb, some people may detect the presence of H2S and consider it a nuissance or annoyance. We noted that the maximum 1-hour concentrations of hydrogen sulphide measured were in the 30 to 40 ppb range. While these values are above the AAAQO, adverse health effects caused by short-term exposure to high concentrations of hydrogen sulphide are not expected to occur until ambient levels reach the 1,000 – 20,000 ppb range and fatal expoure occurs in the 500,000 – 1,000,000 ppb range1.
As long-time Bonnyville residents may have suspected, these spikes in H2S concentrations, often associated with a “rotten” smell, occur most frequently in warm weather and when the wind is blowing from Jessie Lake into town. Analysis of the wind direction (mostly from the south and south-west) and H2S observations reveals a significant statistical relationship; these results provide evidence suggesting that Jessie Lake is the source of the H2S exceedances and the associated odours are not caused by industry or people.
Naturally occurring organic compounds derived from the decay of plant material often cause this musty, earthy, or even rotten egg odour from water bodies. This is something that has been observed in other parts of Alberta, namely Cooking Lake which is approximately 40km east of Edmonton. Even at that distance, it is not uncommon for Edmontonians to smell hydrogen sulphide gas as it is released by the lake during the spring thaw2.
This issue of frequent H2S exceedances from an open area source is a new one for LICA, and we are working with our partners to determine if there is an appropriate management response. LICA’s monitoring efforts around Jessie Lake will continue: The PAMS is going to be relocated to the south side of the Lake to measure H2S concentrations in that area and LICA is working with its watershed stakeholders to determine if there is an appropriate aquatic monitoring response.