De-icing salts are used all around the world to improve driving security. Their impacts on the environment are a major concern, especially due to the production of salted road runoffs that induce rising of salinity of freshwater ecosystems. Some plants tolerate high salt concentrations and are able to accumulate large amounts of salt in their tissues. To protect freshwater ecosystems, constructed wetland incorporating this kind of plant could be used to treat salted road runoffs before they reached natural ecosystems. Lake Saint-Augustin, located near Quebec City (Quebec, Canada) is used as an experimental watershed area. Typha latifolia, Atriplex patula, and Spergularia canadensis have been selected and assessed for their ability to survive and grow in salted waters by accumulating salt in their tissues. Germination (20 days) experiments, recovery experiments (20 days), and chloride accumulation experiments (2 months) have been performed in a controlled environment. The three species showed no germination inhibition for salt concentrations found in the field (0, 150, 1500 mg NaCl/L). Accumulation of chloride has been found significant for all species. Typha latifolia showed the best accumulation of chloride (63 mgCl−/g of dry mass) which corresponds to a standing stock up to 230,000 mgCl⋅m2. This result is promising and supports the decision for upgrading the process to a constructed wetland.

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For several years now, the Natural Resources Canada research facility at CanmetENERGY Devon (AB, Canada) has been performing experiments in a pilot-scale spill tank using 1200 L of river water to examine the physical and chemical behaviors of various crude oil/water mixtures under varying water temperature regimes. Because oil toxicity can be modulated by weathering of the petroleum products, the present study aimed to assess changes in fish embryotoxicity to mixed sweet blend crude oil as it weathered at air and water temperatures of 14°C and 15°C, respectively, for 28 d. The physicochemical behavior of the oil was also monitored. Water samples were taken from the spill tank 5 times during the 28-d experiment on days 1, 6, 14, 21, and 28 and were used to perform toxicity exposures using fathead minnow embryos (Pimephales promelas). For each water sampling day, newly fertilized embryos were exposed to a serial dilution of the spill tank water, noncontaminated river water (used in the spill tank), and a reconstituted water laboratory control. Embryos were raised until hatching. Although mortality was not significantly altered by the oil contamination over the time period, malformation occurrence and severity showed concentration-dependent responses to all contaminated water collected. The results suggest that days 14, 21, and 28 were the most toxic time periods for the fish embryos, which corresponded to increasing concentrations of unidentified oxidized organic compounds detected by a quadropole-time-of-flight system. The present study highlights a novel area for oil research, which could help us to better understand the toxicity associated with oil weathering for aquatic species.

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The demand for rare earth elements (REEs) has increased since the 1990s leading to the development of many mining projects worldwide. However, less is known about how organisms can handle these metals in natural aquatic systems. Through laboratory experiments, we assessed the chronic toxicity and subcellular fractionation of yttrium (Y), one of the four most abundant REEs, in three freshwater organisms commonly used in aquatic toxicology: Daphnia magna , Chironomus riparius, and Oncorhynchus mykiss . In bioassays using growth as an end point, C. riparius was the only organism showing toxicity at Y exposure concentrations close to environmental ones. The lowest observable effect concentrations (LOECs) of Y assessed for D. magna and O. mykiss were at least 100 times higher than the Y concentration in natural freshwater. A negative correlation between Y toxicity and water hardness was observed for D. magna . When exposed to their respective estimated LOECs, D. magna bioaccumulated 15–45 times more Y than the other two organisms exposed to their own LOECs. This former species sequestered up to 75% of Y in the NaOH-resistant fraction, a putative metal-detoxified subcellular fraction. To a lesser extent, C. riparius bioaccumulated 20–30% of Y in this detoxified fraction. In contrast, the Y subcellular distribution in O. mykiss liver did not highlight any notable detoxification strategy; Y was accumulated primarily in mitochondria (ca. 32%), a putative metal-sensitive fraction. This fraction was also the main sensitive fraction where Y accumulated in C. riparius and D. magna . Hence, the interaction of Y with mitochondria could explain its toxicity. In conclusion, there is a wide range of subcellular handling strategies for Y, with D. magna accumulating high quantities but sequestering most of it in detoxified fractions, whereas O. mykiss tending to accumulate less Y but in highly sensitive fractions.