Comparative toxicity of urban wastewater and rainfall overflow in caged freshwater mussel Elliptio complanata

Plastic Analysis with a Plasmonic Nano-Gold Sensor Coated with Plastic-Binding Peptides

Contamination with plastics of small dimensions (<1 µm) represents a health concern for many terrestrial and aquatic organisms. This study examined the use of plastic-binding peptides as a coating probe to detect various types of plastic using a plasmon nano-gold sensor. Plastic-binding peptides were selected for polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), and polystyrene (PS) based on the reported literature. Using nAu with each of these peptides to test the target plastics revealed high signal, at 525/630 nm, suggesting that the target plastic limited HCl-induced nAu aggregation. Testing with other plastics revealed some lack of specificity but the signal was always lower than that of the target plastic. This suggests that these peptides, although reacting mainly with their target plastic, show partial reactivity with the other target plastics. By using a multiple regression model, the relative levels of a given plastic could be corrected by the presence of other plastics. This approach was tested in freshwater mussels caged for 3 months at sites suspected to release plastic materials: in rainfall overflow discharges, downstream a largely populated city, and in a municipal effluent dispersion plume. The data revealed that the digestive glands of the mussels contained higher levels of PP, PE, and PET plastic particles at the rainfall overflow and downstream city sites compared to the treated municipal effluent site. This corroborated earlier findings that wastewater treatment could remove nanoparticles, at least in part. A quick and inexpensive screening test for plastic nanoparticles in biological samples with plasmonic nAu-peptides is proposed.

The influence of rainfall events on the toxicity of urban wastewaters to freshwater mussels Elliptio complanata

The cumulative impacts of rainfall frequency and intensity towards the ecotoxicity of urban pollution is gaining more and more attention in these times of climate change. The purpose of this study was to examine the ecotoxicological impacts of combined sewers overflows and municipal effluent discharge sites during 3 periods (years) of varying intensity precipitations to freshwater mussels Elliptio complanata. Mussels were placed in benthic cages for 3 months during the summer at 2 overflow discharge and 8 km downstream sites including an upstream site for three consecutive years with low (164 mm), medium (182 mm) and high (248 mm) amounts of rain. The results revealed that the effects were mainly influenced by suspended matter loadings and to the dissolved components to a lesser extent. Impacts at the downstream and overflow sites were noticeable at the reproduction (vitellogenin), genotoxicity, neurotoxicity (dopamine and serotonin changes) levels in addition to xenobiotic biotransformation revealed by glutathione S-transferase activity and metallothioneins for organic and heavy metals respectively. The site downstream the effluent produced most of the effects compared to the overflow sites in the Saint-Lawrence River. However, the impacts of combined sewers overflows could become problematic in low dilution systems such as small river and lakes.

Micro and Nanoplastic Contamination and Its Effects on Freshwater Mussels Caged in an Urban Area

Plastic-based contamination has become a major cause of concern as it pervades many environments such as air, water, sediments, and soils. This study sought to examine the presence of microplastics (MPs) and nanoplastics (NPs) in freshwater mussels placed at rainfall/street runoff overflows, downstream (15 km) of the city centre of Montréal, and 8 km downstream of a municipal effluent dispersion plume. MPs and NPs were determined using flow cytometry and size exclusion chromatography using fluorescence detection. Following 3 months of exposure during the summer season, mussels contained elevated amounts of both MPs and NPs. The rainfall overflow and downstream of the city centre were the most contaminated sites. Lipid peroxidation, metallothioneins, and protein aggregates (amyloids) were significantly increased at the most contaminated sites and were significantly correlated with NPs in tissues. Based on the levels of MPs and NPs in mussels exposed to municipal effluent, wastewater treatment plants appear to mitigate plastic contamination albeit not completely. In conclusion, the data support the hypothesis that mussels placed in urbanized areas are more contaminated by plastics, which are associated with oxidative damage. The highest responses observed at the overflow site suggest that tire wear and/or asphalt (road) erosion MPs/NPs represent important sources of contamination for the aquatic biota.