Plume chasing is cost-effective, measuring individual, on-road vehicular emissions. Whereas, wake-flow-generated turbulence results in intermittent, rapid pollutant dilution and substantial fluctuating concentrations right behind the vehicle being chased. The sampling duration is therefore one of the important factors for acquiring representative (average) concentrations, which, however, has been seldom addressed. This paper, which is based on the detailed spatio-temporal dispersion data after a heavy-duty truck calculated by large-eddy simulation (LES), examines how sampling duration affects the uncertainty of the measured concentrations in plume chasing. The tailpipe dispersion is largely driven by the jet-like flows through the vehicle underbody with approximate Gaussian concentration distribution for x ≤ 0.6h, where x is the distance after the vehicle and h the characteristic vehicle size. Thereafter for x ≥ 0.6h, the major recirculation plays an important role in near-wake pollutant transport whose concentrations are highly fluctuating and positively shewed. Plume chasing for a longer sampling duration is more favourable but is logistically impractical in busy traffic. Sampling duration, also known as averaging time in the statistical analysis, thus has a crucial role in sampling accuracy. With a longer sampling (averaging) duration, the sample mean concentration converges to the population mean, improving the sample reliability. However, this effect is less pronounced in long sampling duration. The sampling accuracy is also influenced by the locations of sampling points. For the region x > 0.6h, the sampling accuracy is degraded to a large extent. As a result, acceptable sample mean is hardly achievable. Finally, frequency analysis unveils the mechanism leading to the variance in concentration measurements which is attributed to sampling duration. Those data with frequency higher than the sampling frequency are filtered out by moving average in the statistical analyses.

Heavy metal pollution and the potential for co-selection of resistance to antibiotics in the environment is growing concern. However, clear associations between heavy metals and antibiotic resistance in river systems have not been developed. Here we investigated relationships between total and bioavailable heavy metals concentrations; metal resistance gene (MRG) and antibiotic resistance gene (ARG) abundances; mobile genetic elements; and the composition of local bacterial communities in low and high metal polluted rivers in UK and India. The results indicated that MRGs conferring resistance to cobalt (Co) and nickel (Ni) (rcnA), and Co, zinc (Zn), and cadmium (Cd) (czcA), and ARGs conferring resistance to carbapenem and erythromycin were the dominating resistant genes across the samples. The relative MRGs, ARGs, and integrons abundances tended to increase at high metal polluted environments, suggesting high metals concentrations have a strong potential to promote metal and antibiotic resistance by horizontal gene transmission and affecting bacterial communities, leading to the development of multi-metal and multi-antibiotic resistance. Network analysis demonstrated the positive and significant relationships between MRGs and ARGs as well as the potential for integrons playing a role in the co-transmission of MRGs and ARGs (r > 0.80, p < 0.05). Additionally, the major host bacteria of various MRGs and ARGs that could be accountable for greater MRGs and ARGs levels at high metal polluted environments were also identified by network analysis. Spearman's rank-order correlations and RDA analysis further confirm relationships between total and bioavailable heavy metals concentrations and the relative MRG, ARG, and integron abundances, as well as the composition of related bacterial communities (r > 0.80 (or < −0.80), p < 0.05). These findings are critical for assessing the possible human health concerns associated with metal-driven antibiotic resistance and highlight the need of considering metal pollution for developing appropriate measures to control ARG transmission.

The novel La-MOF@x%PANI composite was synthesized via a two-step procedure with ultra-sonication, and the adsorption mechanism of Pb²⁺ ions from synthetic aqueous solutions was systematically studied. The Pb²⁺ adsorption on the La-MOF@x%PANI was evaluated by the Fourier transform infrared spectroscopy, powder X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray analysis, Brunauer–Emmett–Teller analysis, X-ray photoelectron spectroscopy, and elemental mapping analyses. The effects of the adsorption-influencing parameters, including contact time, solution pH, and co-existing cations on the maximum adsorption capacity of Pb²⁺ onto the prepared composite material were investigated. Moreover, the adsorption of Pb²⁺ ions could be eliminated with rapid adsorption kinetics using the water-stable La-MOF@x%PANI composite. The as-synthesized La-MOF@50%PANI exhibited excellent adsorption performance toward Pb²⁺ ions with an extraordinary adsorption capacity of 185.19 mg/g at pH 6. The Pb²⁺ adsorption onto the La-MOF@x%PANI composite follows the pseudo-second-order kinetics and fits well with the Langmuir isotherm model, indicating the Pb²⁺ adsorption depended on the solution pH as the adsorption mechanism was mainly governed by the electrostatic attraction. Notably, La-MOF@x%PANI composite possesses outstanding regeneration ability and stability after up to four successive cycles. The satisfactory findings reflect that the La-MOF@50%PANI hybrid composite holds a great promise for remediating Pb²⁺ ions from aqueous environments.

Wastewater treatment plants (WwTPs) remove microplastics (MPs) from municipal sewage flow, with the resulting bulk of MPs being concentrated within generated sewage sludge which is frequently recycled back onto agricultural land as accepted practice in many European countries as a sustainable fertiliser resource. This circular process means that MPs successfully removed from WwTPs are deposited into the soil and able to return into the natural watercourse by means of run-off or infiltration to groundwater. This study quantifies the removal efficiency of MPs with size ranging between 1000 and 5000 μm in a primary settlement tank (PST) at a WwTP serving a population equivalent of 300,000 and provides MP concentrations in the generated sewage sludge. Our study revealed that the proportion of MPs partitioning in a PST to settled sludge, floating scum and effluent was 96%, 4% and 0% respectively, implying 100% removal of MPs of 1000–5000 μm in size. The generated sewage sludge was estimated to contain concentrations of approximately 0.01 g of MPs or 24.7 MP particles per g of dry sewage sludge solid, equivalent to ∼1% of the sewage sludge weight. Using these figures and data from the European Commission and Eurostat, the potential yearly MP contamination onto soils throughout European nations is estimated to be equivalent to a mass of MPs ranging between 31,000 and 42,000 tonnes (considering MPs 1000–5000 μm in size) or 8.6×10¹³–7.1×10¹⁴ MP particles (considering MPs 25–5000 μm in size). An estimated maximum application rate of 4.8 g of MP/m²/yr or 11,489 MP particles/m²/yr, suggests that the practice of spreading sludge on agricultural land could potentially make them one of the largest global reservoirs of MP pollution. Hence, recycling raw sewage sludge onto agricultural soils should be reviewed to avoid introducing extreme MP pollution into the environment.

The exposure of benzo [a]pyrene (BaP) in recent times is rather unavoidable than ever before. BaP emissions are sourced majorly from anthropogenic rather than natural provenance from wildfires and volcanic eruptions. A major under-looked source is via the consumption of foods that are deep-fried, grilled, and charcoal smoked foods (meats in particular). BaP being a component of poly aromatic hydrocarbons has been classified as a Group I carcinogenic agent, which has been shown to cause both systemic and localized effects in animal models as well as in humans; has been known to cause various forms of cancer, accelerate neurological disorders, invoke DNA and cellular damage due to the generation of reactive oxygen species and involve in multi-generational phenotypic and genotypic defects. BaP's short and accumulated exposure has been shown in disrupting the fertility of gamete cells. In this review, we have discussed an in-depth and capacious run-through of the various origins of BaP, its economic distribution and its impact as well as toxicological effects on the environment and human health. It also deals with a mechanism as a single compound and its ability to synergize with other chemicals/materials, novel sensitive detection methods, and remediation approaches held in the environment.

PAHs have been widely detected to accumulate in saline and hypersaline environments. Moderately halophilic microbes are considered the most suitable player for the elimination of PAHs in such environments. In this study, consortium 5H was enriched under 5% salinity and completely degraded phenanthrene in 5 days. By high-throughput sequencing, consortium 5H was identified as being mainly composed of Methylophaga, Marinobacter and Thalassospira. Combined with the investigation of intermediates and enzymatic activities, the degradation pathway of consortium 5H on phenanthrene was proposed. Consortium 5H was identified as having the ability to tolerate a wide range of salinities (1%–10%) and initial PAH concentrations (50 mg/L to 400 mg/L). It was also able to function under neutral to weak alkaline conditions (pH from 6 to 9) and the phytotoxicity of the produced intermediates showed no significant difference with distilled water. Furthermore, the metagenome of consortium 5H was measured and analyzed, which showed a great abundance of catabolic genes contained in consortium 5H. This study expanded the knowledge of PAH-degradation under hypersaline environments and consortium 5H was proposed to have good potential for the elimination of PAH pollution in saline/hypersaline environments.

Persistent organic pollutants (POPs) are pervasive and a significant threat to the environment worldwide. Yet, reports of POP levels in Antarctic seabirds based on blood are scarce, resulting in significant geographical gaps. Blood concentrations offer a snapshot of contamination within live populations, and have been used widely for Arctic and Northern Hemisphere seabird species but less so in Antarctica. This paper presents levels of legacy POPs (polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs)) and novel brominated flame retardants (NBFRs) in the blood of five Antarctic seabird species breeding within Prydz Bay, East Antarctica. Legacy PCBs and OCPs were detected in all species sampled, with Adélie penguins showing comparatively high ∑PCB levels (61.1 ± 87.6 ng/g wet weight (ww)) compared to the four species of flying seabirds except the snow petrel (22.5 ± 15.5 ng/g ww), highlighting that legacy POPs are still present within Antarctic wildlife despite decades-long bans. Both PBDEs and NBFRs were detected in trace levels for all species and hexabromobenzene (HBB) was quantified in cape petrels (0.3 ± 0.2 ng/g ww) and snow petrels (0.2 ± 0.1 ng/g ww), comparable to concentrations found in Arctic seabirds. These results fill a significant data gap within the Antarctic region for POPs studies, representing a crucial step forward assessing the fate and impact of legacy POPs contamination in the Antarctic environment.

Along the South Carolina coast (U.S.) where the ecologically and economically important eastern oyster (Crassostrea virginica) forms extensive intertidal reefs, recent surface water surveys found that fibers, fragments, and microscopic tire particles represented 43.6%, 30.9%, and 17.7% of the total microplastics, respectively. The aim of this study was to characterize accumulation and depuration of these particles in eastern oysters. Oysters were exposed to purple polyethylene fibers, green nylon fragments, or micronized crumb rubber at a concentration of 5000 microplastics/L, and sacrificed after 0, 24, 48, and 96 h to characterize uptake. Following 96 h, remaining oysters were transferred to microplastic-free brackish water and sacrificed at 24, 48, and 96 h to characterize depuration. For fibers and fragments, levels increased in a nonlinear fashion reaching 1.61 ± 0.6 particles/g w. w. (mean ± SE) and 0.46 ± 0.1 particles/g w. w. after 96 h, respectively. Conditional uptake clearance rate constants (kᵤ) were estimated to be 0.0084 and 0.0025 mL/g*h for fibers and fragments, respectively. For crumb rubber, levels increased in a linear fashion reaching 3.62 ± 0.8 particles/g w. w. after 96 h, and the kᵤ value was estimated to be 0.0077 mL/g*h. Depuration was best described using a two-compartment (double exponential) model suggesting the presence of fast and slow compartments. Conditional depuration rate constants (kd) for the slow compartments were 0.0084, 0.0205, and 0.0048/h for fibers, fragments, and crumb rubber, respectively. These results demonstrate accumulation and depuration of microplastics in eastern oysters is size-and shape-dependent. Depuration, which is a common practice for shellfish safety, is an effective way to reduce microplastic loads in eastern oysters, but the minimum recommended time of 44 h would only reduce loads of these particles by 55.5–67.6%.

Organic matter from salmon farms has been shown to be assimilated by soft sediment and rocky reef communities within the ecological footprint of salmon farms. Given these findings, another question arises – What other chemicals in salmon feed may be assimilated into wild communities via organic waste from salmon farms? Here we measured a suite of organic contaminants in salmon feed, in organisms used in a controlled feeding experiment, and in reef species collected within the depositional footprint of salmon farms. Gas Chromatography-Tandem Mass Spectrometry was used to quantify trace concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and current-use (CPUs) and historic-use pesticides (HUPs) in salmon feed imported to New Zealand. The effect of assimilation of farm-derived organic matter on contaminant profiles differed among species during the controlled feeding experiment and demonstrated that migration of individuals to a farm-associated site has the potential to increase or decrease organic contaminant concentrations. Concentrations of PCBs in Parapercis colias (blue cod), a highly resident, long-lived fish, were significantly higher at farm sites than at reference sites. While these concentrations were relatively low in a global context, this result presents blue cod as an important candidate for future monitoring of organic contaminants around point sources. PCBs and PBDEs measured in wild marine species were all below limits set by the European Union, whereas concentrations of certain HUPs, specifically dichlorodiphenyltrichloroethane (DDT) and its degradation products and endosulfan, may be of concern as a consequence of alternative anthropogenic activities. Overall, feed imported to New Zealand had relatively low levels of most organic contaminants that, at current levels, are unlikely to result in significant ecological effects to wild communities in adjacent habitats.

This study aims to better understand the aging characteristics of microplastics in the environment and the influence of aging microplastics on the migration and transformation of organic pollutants. In this study, polyvinyl chloride (PVC) and polyethylene (PE) were chosen as research objects, and the effects of two aging methods (freeze-thaw cycle aging and high-temperature oxidation aging) on their surface properties and atrazine (ATZ) sorption were investigated. The crystallinity of PE increased after freeze-thaw cycling and decreased after high-temperature oxidation. The freeze-thaw cycle destroys the amorphous region of PE, reducing the micropores on the PE surface and decreasing the ATZ adsorbed by PE. Although aging had no significant effect on the surface structure of PVC, it caused new oxygen-containing functional groups to be produced on the PVC surface, which reduced the ATZ adsorption capacity. These results show that the two aging modes change the surface properties of PVC and PE, thus affecting the sorption mechanism of ATZ, and provide a theoretical premise for the natural behavior and ecological chance assessment of ATZ in the presence of microplastics.