Ed Sverko

Public and scientific concern has grown over the last decade in Canada over the cosmetic use of pesticides in urban centers. With this in mind, a national survey was designed to monitor eight commonly used herbicides in urban rivers and streams across Canada. To coordinate sample collections across the country, samples were collected monthly on one of two predetermined dates from April to September, 2007 from 19 sites within 16 watersheds, including 15 sites downstream of urban lands and two reference sites. Water samples were also collected approximately three times from each watershed during or after precipitation events. All samples were collected using a common sampling protocol and all were analyzed using the same analytical laboratories. The herbicides 2,4-D, mecoprop, dicamba, glyphosate and its major metabolite aminomethylphosphonic acid (AMPA) were most frequently detected. Using either herbicide concentrations upstream/downstream of urban centers or bromoxynil and clopyralid as indictors of agricultural inputs of herbicides to streams, it was clear that environmental concentrations of these herbicides downstream of urban areas were linked to urban use in Canada. Herbicide concentrations in streams draining urban areas were greater during or after significant rainfall events and, with the exception of glyphosate, were significantly greater in the Province of Ontario. Herbicide concentrations were not correlated to the proportion of the watersheds in urban land use. Also, there was no difference in seasonal patterns of herbicide concentrations across urban centers when grouped in five geographic areas. None of the herbicide concentrations measured exceeded existing Canadian Water Quality Guidelines for the protection of aquatic life. This is the first time a national survey of pesticides in urban rivers has been carried out in a consistent fashion across Canada. Concentrations of 2,4-D, mecoprop, dicamba, glyphosate, and AMPA were linked to urban use and frequently detected in all geographic areas. However, geographic differences in concentration suggested differences in usage or stream connectivity patterns among urban centers. Some jurisdictions in Canada have recently restricted cosmetic use of pesticides and it would be interesting to determine whether such restrictions will lead to reduced pesticide concentrations in urban streams.

The historical occurrence of Dechlorane Plus (DP) and detection of novel compounds structurally related to DP is described in a dated Lake Ontario sediment core. Our core was collected near the mouth of the Niagara River, which is known to be a major source of DP to the lake. Maximum DP concentrations (920 ng g⁻¹, dry weight) were observed between 1976 and 1980, the highest reported to date. Following that time, we observed a dramatic decrease in DP concentration which coincided with the enactment of United States federal and state laws to mitigate free release of chemicals into the Niagara River and installation of an industrial wastewater treatment facility. During the course of our research, four new substances structurally related to DP were also identified. These compounds were thought to arise from the Diels−Alder reactions resulting from impurities present in 1,5-cyclooctadiene, a feedstock used in production of DP. To confirm our hypothesis, Diels−Alder reactions were performed on the individual impurities. Using different stationary-phase capillary gas chromatography columns and high-resolution mass spectrometry, we were able to positively identify some of these novel compounds in the core. Interestingly, we also were able to identify a monoadduct compound, formed by addition of 1 mol of hexachlorocyclopentadiene to 2 mol of 1,3-cyclooctadiene, in lake trout. The concentration of this monoadduct was approximately 2 orders of magnitude greater than that of DP, suggesting that it is more bioaccumulative.

(2009). Sample preparation methods for the analysis of poly-methylene interrupted fatty acids. SIL Proceedings, 1922-2010: Vol. 30, No. 6, pp. 903-906.

A recently discovered chlorinated flame retardant, Dechlorane Plus (DP), was reported in air and a sediment core within the North American Great Lakes region. To further reveal the fate of DP in the Great Lakes, 40 surficial sediments from Lakes Erie and Ontario and two additional cores were analyzed using newly available analytical grade DP isomer solutions. The maximum total concentration in Lake Ontario was over 60-fold higher than Lake Erie, 586 ng/g and 8.62 ng/g, respectively. Additionally, analysis of archived suspended sediments collected from the Niagara River (1980–2002) showed a declining total DP concentration of 89 ng/g to 7.0 ng/g, suggesting a possible decrease in production or the reduction of free DP released into the environment during manufacturing. The average syn-DP fractional abundance (f_syn) in our study was less than the commercial DP composition indicating a stereoselective enrichment of anti-DP in the environment. Mean f_syn profiles were uniquely similar to both Lake Ontario and the Niagara River in comparison to Lake Erie. During the course of our analysis we noticed an increasing f_syn value in the calibration standard which became exacerbated as the liner got dirtier and suggested the prospect of DP degradation. Follow-up studies indicated these compounds were dechlorinated DP species produced on the injection liner. Using a clean injection liner, these degradates were also detected in sediments from the Niagara River and Lake Ontario; tentatively identified as [−Cl+H] and [−2Cl+2H] by high resolution mass spectrometry. The observed similarity of f_syn profiles between Lake Ontario and Niagara River and the detection of the degradates only in their locations, suggest to us that the river is a major source to Lake Ontario’s DP burden. To our knowledge, this is the first report of DP degradates in the environment.