Publications by authors named "Helena Steer"

Background: Chlorinated paraffins (CPs) are industrial chemicals categorised as persistent organic pollutants because of their toxicity, persistency and tendency to long-range transport, bioaccumulation and biomagnification. Despite having been the subject of environmental attention for decades, analytical methods for CPs still struggle reaching a sufficient degree of accuracy. Among the issues negatively impacting the quantification of CPs, the unavailability of well-characterised standards, both as pure substances and as matrix (certified) reference materials (CRMs), has played a major role.

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We investigated short-chain (C ) chlorinated paraffins (SCCP) in an Arctic marine food web. In zooplankton, fishes, and ringed seals from western Hudson Bay, Canada, SCCP concentrations ranged from 38.3 to 687 ng g lipid weight.

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Several methods were developed to detect the cyclic volatile methylsiloxanes (cVMSs) including octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) in water, sediment, soil, biota, and biosolid samples. Analytical techniques employed to optimize measurement of this compound class in various matrices included membrane-assisted solvent extraction in water, liquid-solid extraction for sediment, soil, biota, and biosolid samples. A subsequent analysis of the extract was conducted by large-volume injection-gas chromatography-mass spectrometry (LVI-GC-MS).

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A comprehensive surveillance program was conducted to determine the occurrence of three cyclic volatile methylsiloxanes (cVMS) octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) in environmental compartments impacted by wastewater effluent discharges. Eleven wastewater treatment plants (WWTPs), representative of those found in Southern Ontario and Southern Quebec, Canada, were investigated to determine levels of cVMS in their influents and effluents. In addition, receiving water and sediment impacted by WWTP effluents, and biosolid-amended soil from agricultural fields were also analyzed for a preliminary evaluation of the environmental exposure of cVMS in media impacted by wastewater effluent and solids.

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Recent regulations require that the ecological effects of microorganisms introduced into the environment, such as for groundwater bioremediation, be assessed prior to their utilization. A native anuran (Rana clamitans) and a model anuran (Xenopus laevis) were used as potential wetland receptors of tetrachloroethylene (PCE)-contaminated groundwater, undergoing three bioremediation treatments: natural attenuation (NA), biostimulation (ST), and bioaugmentation (AU). Eggs of both species were exposed acutely (96 h) to remediated effluents.

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