A wide variety of sampling techniques and strategies are needed to analyze polycyclic aromatic compounds (PACs) and interpret their distributions in various environmental media (i.e., air, water, snow, soils, sediments, peat and biological material). In this review, we provide a summary of commonly employed sampling methods and strategies, as well as a discussion of routine and innovative approaches used to quantify and characterize PACs in frequently targeted environmental samples, with specific examples and applications in Canadian investigations. The pros and cons of different analytical techniques, including gas chromatography – flame ionization detection (GC-FID), GC low-resolution mass spectrometry (GC-LRMS), high performance liquid chromatography (HPLC) with ultraviolet, fluorescence or MS detection, GC high-resolution MS (GC-HRMS) and compound-specific stable (δ¹³C, δ²H) and radiocarbon (Δ¹⁴C) isotope analysis are considered. Using as an example research carried out in Canada’s Athabasca oil sands region (AOSR), where alkylated polycyclic aromatic hydrocarbons and sulfur-containing dibenzothiophenes are frequently targeted, the need to move beyond the standard list of sixteen EPA priority PAHs and for adoption of an AOSR bitumen PAC reference standard are highlighted.

Polycyclic aromatic hydrocarbons (PAHs) are a byproduct of combustion processes. They are common pollutants in oil-producing countries because fossil fuel processing generates PAHs that associate with dust. Airborne particles containing PAHs are transported into houses during dust storms, which are common in the arid oil-producing countries, and consequently the children and adults in the household are exposed to PAHs in indoor house dust. The goal of this study was to present a systematic survey of PAHs in indoor house dust in Kuwait. The PAHs concentrations and composition of indoor house dust was determined, along with their probable source and the potential carcinogenic risks. Total PAHs concentrations (ƩPAH) were, on average (±standard deviation) 1112 ± 347 μg/kg and ranged from 450 to 2242 μg/kg. Heavier congeners (4–6 ring PAHs) represented 61% of the ƩPAH. Petroleum combustion and traffic emissions were the major source of PAHs, based on the isomeric ratios of PAHs in indoor house dust. The incremental lifetime cancer risks (ILCRs) of exposure to PAHs in indoor house dust was 2.23 × 10⁻³ (95% CI: 1.99 × 10⁻³ – 2.48 × 10⁻³) for children and 2.15 × 10⁻³ (95% CI: 1.94 × 10⁻³ – 2.37 × 10⁻³) for adults, exceeding the US EPA safe limit of 1 × 10⁻⁶. Therefore, exposure to PAHs present in indoor house dust increases the cancer risk for children and adults in Kuwait.

Pharmacologically active compounds found in reclaimed wastewater irrigation or animal manure fertilizers pose potential risks for agriculture. The mechanism underlying the effects of ketoprofen on rice (Oryza sativa L.) seedlings was investigated. The results showed that low concentrations (0.5 mg L⁻¹) of ketoprofen slightly stimulate growth of rice seedlings, while high concentrations can significantly inhibit growth by reducing biomass and causing damage to roots. Ketoprofen affects photosynthetic pigment content (Chla, Chlb, and carotenoids) and chlorophyll synthesis gene (HEMA, HEMG, CHLD, CHLG, CHLM, and CAO) expression. Fluorescence parameters such as minimum fluorescence (F₀), maximum fluorescence (Fₘ), variable fluorescence (Fᵥ), potential photosynthetic capacity (Fᵥ/F₀), maximum quantum efficiency of PSII photochemistry (Fᵥ/Fₘ), electron transfer rate (ETR), and Y(II), Y(NPQ), Y(NO) values were affected, showing photosynthetic electron transfer was blocked. Active oxygen radical (O₂•−and H₂O₂), malondialdehyde and proline content increased. Superoxide dismutase, catalase and ascorbate peroxidase activities, glutathione content and antioxidant-related gene (FSD1, MSD1, CSD1, CSD2, CAT1, CAT2, CAT3, APX1, APX2) expression were induced. Higher integrated biomarker response values of eight oxidative stress response indexes were obtained at higher ketoprofen concentrations. Ultrastructure observation showed that ketoprofen causes cell structure damage, chloroplast swelling, increase in starch granules, and reduction in organelles. This study provides some suggested toxicological mechanisms and biological response indicators in rice due to stress from pharmacologically active compounds.

Demand for aquatic products surges, due to the increasing concerns on high-quality nutrition and food security. Eastern China is the leading area in contributing significantly to both production and consumption of aquatic products from inland aquaculture, coastal fishing, and distant-water fishing. It is imperative to comprehensively assess the dietary risks of common chemical hazards, such as polycyclic aromatic hydrocarbons (PAHs) in aquatic products of these supply origins, and the contribution of aquatic product consumption to total human exposure. The observed body loads of total PAHs in the coastal aquatic products varied significantly, indicating an unstable food quality from the east coast of China. In the meantime, benzo[a]pyrene equivalent concentrations (BaPₑq) exhibited the highest level in the aquatic products from inland farm ponds. High BaPₑq, along with high consumption of inland aquaculture products, led to higher corresponding cumulative carcinogenic risks (ILCRs) than the other two kinds of products, which further indicate that the origins and consumption rates of the aquatic products do matter. Furthermore, it is confirmed that the consumption of aquatic products is an important contributor to the total daily exposure to PAHs, especially for children and pregnant women. Finally, it is necessary to apply practical remediation in aquaculture farm ponds to provide high-quality products, especially for the population groups of children and pregnant women, and alleviate the exposure and risk due to the PAHs in aquatic products.

Fluoxastrobin is one of the most widely used strobilurin fungicides, however, application of the fungicides may result in soil residues leading to environmental damage including oxidative stress and damage to sentinel organisms (i.e. earthworms). While this has been demonstrated in artificial soil, the biochemical response of Eisenia fetida exposed to fluoxastrobin in natural soils is unclear. This study utilized three typical natural soils (fluvo-aquic soils, red clay, and black soils) to evaluate the biochemical response of Eisenia fetida exposed to fluoxastrobin (0.1, 1.0, 2.5 mg/kg) including the production of reactive oxygen species, impact on three enzyme activities, lipid peroxidation, and 8-hydroxydeoxyguanosine after a 4-week exposure. The effects of fluoxastrobin on Eisenia fetida in different soils were assessed using an integrated biomarker response (IBR). The findings may be possible to state that the toxic effects of fluoxastrobin in artificial cannot exactly represent that in natural soils. Specifically, the fluoxastrobin subchronic toxicity was highest in red clay and lowest in black soil among the three natural soils. Furthermore, the 8-OHdG content was more sensitive to fluoxastrobin in all six environmental indicators of the present study.

Metalaxyl is a broad-spectrum chiral fungicide that used for the protection of plants, however extensive use of metalaxyl resulted in serious environmental problems. Thus, a study on the detoxification mechanism in algae/cyanobacteria and their ability for phycoremediation is highly recommended. Here, we investigated the physiological and biochemical responses of two cyanobacterial species; Anabaena laxa and Nostoc muscorum to R-metalaxyl toxicity as well as their ability as phycoremediators. Two different levels of R-metalaxyl, at mild (10 mg/L) and high dose (25 mg/L), were applied for one-week. We found that A. laxa absorbed and accumulated more intracellular R-metalaxyl compared to N. muscorum. R-metalaxyl, which triggered a dose-based reduction in cell growth, photosynthetic pigment content, and photosynthetic key enzymes’ activities i.e., phosphoenolpyruvate carboxylase (PEPC) and ribulose‒1,5‒bisphosphate carboxylase/oxygenase (RuBisCo). These decreases were significantly less pronounced in A. laxa. On the other hand, R-metalaxyl significantly induced oxidative damage markers, e.g., H₂O₂ levels, lipid peroxidation (MDA), protein oxidation and NADPH oxidase activity. However, these increases were also lower in A. laxa compared to N. muscorum. To alleviate R-metalaxyl toxicity, A. laxa induced the polyphenols, flavonoids, tocopherols and glutathione (GSH) levels as well as peroxidase (POX), glutathione peroxidase (GPX), glutathione reductase (GR) and glutathione-s-transferase (GST) enzyme activities. On the contrary, the significant induction of antioxidants in N. muscorum was restricted to ascorbate, catalase (CAT) and ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR) enzyme activities. Although A. laxa accumulated more R-metalaxyl, it experienced less stress due to subsequent induction of antioxidants. Therefore, A. laxa may be a promising R-metalaxyl phycoremediator. Our results provided basic data for understanding the ecotoxicology of R-metalaxyl contamination in aquatic habitats and the toxicity indices among cyanobacteria.

Diet is an important route of mercury (Hg) uptake in marine organisms. Trophic transfer of Hg throughout the food webs may be influenced by various factors, including diet and Hg speciation. Bivalves such as oysters are widely used as bioindicators of trace element pollution such as Hg. Nevertheless, our current knowledge regarding their ability to accumulate Hg from their diet is mainly based on experiments performed using phytoplankton. In their natural environment, oysters feed on a variety of food items including ciliates, detritus, in addition to phytoplankton. The present study aimed at examining the influence of diet composition on the trophic transfer of inorganic Hg (iHg) and methylmercury (MeHg) in the Pacific cupped oyster Crassostrea gigas. The pulse-chase feeding method was used with two radiolabeled food items: a heterotrophic protist (Uronema marinum) and a phytoplanktonic diatom (Thalassiosira pseudonana). Depuration of dietary Hg in the oysters was followed for 50 d. Kinetic parameters including assimilation efficiency (AE) and efflux rate constant (kₑ) were calculated. Our results showed that oysters fed on ciliates assimilated 96 ± 1% and 31 ± 2% of the ingested MeHg and iHg, respectively whereas these elements were similarly assimilated in the oysters fed on phytoplankton (78 ± 3% and 86 ± 4% for MeHg and iHg, respectively). Mercury assimilation in oyster is thus diet dependent (significant differences in AE, p < 0.05), metal species-dependent and likely resulting from variations in Hg bioavailability in the two food items tested and a gut passage time-dependent of the ingested matrix.

Microorganisms in coastal sediments are fundamental for ecosystem functioning, and regulate processes relevant in global biogeochemical cycles. Still, our understanding of the effects anthropogenic perturbation and pollution can have on microbial communities in marine sediments is limited. We surveyed the microbial diversity, and the occurrence and abundance of metal and antibiotic resistance genes is sediments collected from the Pula Bay (Croatia), one of the most significantly polluted sites along the Croatian coast. With a collection of 14 samples from the bay area, we were able to generate a detailed status quo picture of a site that only recently started a cleaning and remediation process (closing of sewage pipes and reduction of industrial activity). The concentrations of heavy metals in Pula Bay sediments are significantly higher than in pristine sediments from the Adriatic Sea, and in some cases, manifold exceed international sediment quality guidelines. While the sedimentary concentrations of heavy metals did significantly influence the abundance of the tested metal resistance genes, no strong effect of heavy metal pollution on the overall microbial community composition was observed. Like in many other marine sediments, Gammaproteobacteria, Bacteroidota and Desulfobacterota dominated the microbial community composition in most samples, and community assembly was primarily driven by water column depth and nutrient (carbon and nitrogen) availability, regardless of the degree of heavy metal pollution.

As glyphosate-based herbicides, sold under the commercial name Roundup®, represent the most used herbicides in the world, contamination of the freshwater environment by glyphosate has become a widespread issue. In Italy, glyphosate was detected in half of the surface waters monitoring sites and its concentrations were higher than environmental quality standards in 24.5% of them. It can last from days to months in water, leading to exposure for aquatic organisms and specifically to amphibians’ larvae that develop in shallow water bodies with proven effects to development and behaviour. In this study, we tested the effects of a 96 h exposure during embryonic development of marsh frog’s tadpoles to three ecologically relevant Roundup® Power 2.0 concentrations. As expected, given the low concentrations tested, no mortality was observed. Morphological measurements highlighted a reduction in the total length in tadpoles exposed to 7.6 mg a.e./L, while an increase was observed at lower concentrations of 0.7 and 3.1 mg a.e./L compared to control group. Tadpoles raised in 7.6 mg a.e./L also showed a smaller tail membrane than those raised in the control solution. Regarding behaviour, we tested tadpoles in two different sessions (Gosner stages 25 and 28/29) for lateralization, antipredator response and basal activity. Lower intensity of lateralization was detected in tadpoles raised at the highest Roundup® concentration in the first session of observation, while no significant difference among treatments was observed in the second one. In both sessions, effects of Roundup® Power 2.0 embryonic exposure on antipredator response, measured as the proportional change in activity after the injection of tadpole-fed predator (Anax imperator) cue, were not detected. Tadpoles exposed during embryonic development to Roundup® exhibited lower basal activity than the control group, with the strongest reduction for the 7.6 mg a.e./L treatment. Our results reinforce the concern of Roundup® contamination impact on amphibians.

Plastic pollution represents one of the most salient indicators of society’s impact on the environment. The microplastic component of this is ubiquitous, however, microplastic studies are seldom representative of the locations they sample. Over 12 months we explored spatiotemporal variation in microplastic prevalence across a freshwater system and in atmospheric deposition within its catchment, in one of the most temporally comprehensive studies of microplastic pollution. Microplastics were quantified in low concentrations (max 0.4 particles L⁻¹) at all freshwater sites, including upstream of urban areas, and on rivers that do not receive wastewater treatment plant effluent. Extrapolated microplastic abundances at each site varied by up to 8 orders of magnitude over the course of the sampling campaign, suggesting that microplastic surveys that do not account for temporal variability misrepresent microplastic prevalence. Whilst we do not wish to underplay the potential impacts of microplastic particles in the environment, we argue that microplastic pollution needs to be placed in a more critical context, including assessment of temporal variability, to appropriately inform legislators and consumers.