The sorption behavior of phthalate additives in plastic and microplastic litter is an important process controlling the exposure, net health risk and ecotoxicity of these co-occurring pollutants. Plastic crystallinity and particle morphology are hypothesized to be important variables for microplastics sorption behavior, but to date there have been few direct studies to explicitly test for the influence of these parameters. To address this, in this study we explored the sorption of dibutyl phthalate (DBP) as a probe molecule to diverse polyethylene microplastics including irregularly-shaped pure polyethylene microplastics (IPPM), black plastic film microplastics (BPFM), white plastic film microplastics (WPFM), and commercial microspheres (CM), which had crystallinities ranging from 17 to 99%. Sorption kinetics for all materials could be well represented with both a pseudo-first-order (R² = 0.87–0.93) and pseudo-second-order model (R² = 0.87–0.93). Further, sorption was highly linear in the concentration range of 0.5–10 mg L⁻¹, with no greater performance from a linear sorption model (R² = 0.96–0.99) than the non-linear Freundlich or Temkin sorption models. The partition coefficient (Kd) of DBP sorption onto IPPM, BPFM, WPFM and CMs were 1974.55 L kg⁻¹, 1483.85 L kg⁻¹, 1477.45 L kg⁻¹ and 509.37 L kg⁻¹, respectively, showing a significant decrease with increasing crystallinity (r² = 0.98). The particle size of microplastics (27–1000 μm) is, however, an indecisive factor affecting their sorption behavior for DBP in this study. This study provides new insight that crystallinity plays a governing role on the sorption of phthalate from microplastic. This should be considered in future exposure studies and assessments of phthalates from plastics and microplastics.

Low-cost air quality sensors can help increase spatial and temporal resolution of air pollution exposure measurements. These sensors, however, most often produce data of lower accuracy than higher-end instruments. In this study, we investigated linear and random forest models to correct PM₂.₅ measurements from the Denver Department of Public Health and Environment (DDPHE)’s network of low-cost sensors against measurements from co-located U.S. Environmental Protection Agency Federal Equivalence Method (FEM) monitors. Our training set included data from five DDPHE sensors from August 2018 through May 2019. Our testing set included data from two newly deployed DDPHE sensors from September 2019 through mid-December 2019. In addition to PM₂.₅, temperature, and relative humidity from the low-cost sensors, we explored using additional temporal and spatial variables to capture unexplained variability in sensor measurements. We evaluated results using spatial and temporal cross-validation techniques. For the long-term dataset, a random forest model with all time-varying covariates and length of arterial roads within 500 m was the most accurate (testing RMSE = 2.9 μg/m³ and R² = 0.75; leave-one-location-out (LOLO)-validation metrics on the training set: RMSE = 2.2 μg/m³ and R² = 0.93). For on-the-fly correction, we found that a multiple linear regression model using the past eight weeks of low-cost sensor PM₂.₅, temperature, and humidity data plus a near-highway indicator predicted each new week of data best (testing RMSE = 3.1 μg/m³ and R² = 0.78; LOLO-validation metrics on the training set: RMSE = 2.3 μg/m³ and R² = 0.90). The statistical methods detailed here will be used to correct low-cost sensor measurements to better understand PM₂.₅ pollution within the city of Denver. This work can also guide similar implementations in other municipalities by highlighting the improved accuracy from inclusion of variables other than temperature and relative humidity to improve accuracy of low-cost sensor PM₂.₅ data.

The recent emergence of plasmid-borne mobilized colistin resistance (mcr) genes largely challenges the clinical use of colistin. Monitoring the distribution of mcr genes in environment is important for aiding to develop effective control measures. In this study, we aimed to evaluate the occurrence of a recent reported mcr variant, mcr-10, in hospital sewage water. mcr-10 was identified in three Enterobacter roggenkampii strains with high-level colistin resistance (MIC ≥ 16 mg/L). The three strains were assigned to different sequence types suggesting a sporadic dissemination of mcr-10 in the sewage water. Pairwise comparisons of the predicted protein structures of ten mcr homologues revealed that MCR-10 shares a higher similarity with MCR-3, MCR-4, MCR-7, and MCR-9. Overexpression in Escherichia coli Top10 showed that the activity of mcr-10 against colistin is lower than that of mcr-9. mcr-10 expression can be specifically induced by colistin, and it was co-upregulated with phoPQ to mediate the high-level colistin resistance. The mcr-10 gene was detected on self-transmissible plasmids in two isolates and on the chromosome in the other one. Blasting in Genbank suggested that the two mcr-10-bearing plasmids (pECL981-1 and pECL983-1) were novel plasmids, and replicon typing showed that they belong to IncFIB-FII and IncFIB, respectively. Plasmid-curing assay evidence that pECL981-1 was lack of fitness cost for the host. Three novel types of the genetic context were found for the mcr-10 gene in the three isolates. The structure xerC-mcr10 was dominant in mcr-10-positive genomes (39/42) retrieved in Genbank, suggesting that xerC might be involved in the mobilization of mcr-10. To our knowledge, this is the first report of mcr-10-producing E. roggenkampii detected in hospital sewage water. Our study highlights that continuous monitoring of mcr genes in hospital sewage water is imperative for understanding and tackling the dissemination.

Chlorine-based compounds are typical persistent organic pollutants (POPs) that are widely generated in industrial production. This paper reports an effective and rapid pulsed laser irradiation technique for the dechlorination of hexachlorobenzene (HCB), a model pollutant, without additional catalysts or supports. The effects of the laser parameters, including the laser wavelength and power, on the dechlorination efficiency, were also investigated. The optimized results showed that a lower laser wavelength of 266 nm with 10 mJ/pulse power exhibited the highest dechlorination efficiency with 95% within 15 min. In addition, the laser beam effect was examined by designing the direct-pulsed laser single and multipath irradiation system. The results showed that improving the laser beam profile resulted in more than 95% dechlorination efficiency within 5 min. Thus, the dechlorination reaction proceeded much faster as the surface area that the laser beam came in contact with increased due to the multipath system than the single pathway. Gas chromatography identified benzene as the final product of HCB with pentachlorobenzene (PCB), tetrachlorobenzene (TeCB), trichlorobenzene (TCB), dichlorobenzene (DCB), and chlorobenzene (CB) as intermediate products. The mechanism of HCB dechlorination was explained by a comparison of theoretical calculations with the experimental results. The present study reports an advanced technique for the complete dechlorination of chlorobenzenes, which holds great application potential in environmental remediation.

Large amounts of antibiotics/disinfectants are used in the farming of ornamental fish so as to prevent and treat bacterial infection. This may exert considerable selection pressures on the prevalence and propagation of antibiotic resistance genes (ARGs). However, the levels of ARGs and their potential prevalence mechanism in the wastewater of the ornamental fish industry remains unclear. In this work, wastewater is collected from a representative ornamental fish market (OFM) that is located at the northern China to study the occurrence and abundance of 21 ARGs and 2 integrase genes. Results indicated that 15 different ARGs and 2 integrase genes are existent and prevalent in the wastewater of OFM, whereby concentrations range from 2.01 to 10.34 copies/L. Proteobacteria, Bacteroidetes, Verrucomicrobia, and Firmicutes are the predominant phyla in the wastewater samples. 17 species of human opportunistic pathogens are present with relative abundance of up to 0.01%, which suggests a considerable risk of pathogens acquiring and disseminating ARGs. Moreover, oxytetracycline, ciprofloxacin, norfloxacin, sulfadiazine, and chloramphenicol are most frequently detected in wastewater, with concentrations of up to 1150, 877, 514, 1970, and 1700 ng/L, respectively. Notably, good correlations have been determined among ARGs and antibiotics, non-antibiotic environmental factors in wastewater of OFM. This current study reveals, for the first time, that OFM is a previously unperceived reservoir for ARG prevalence in aquatic environment and water environmental factors (particularly antibiotics), and their induced shifts in the microbial communities are the key factors for distribution of ARGs in OFM.

Nicosulfuron is a sulfonylurea family herbicide which is commonly applied together with the triazine herbicide atrazine in agricultural practice. However, whether nicosulfuron can influence the biodegradation of atrazine is unclear. Therefore, the influence of nicosulfuron on atrazine removal as well as on cell viability and transcription of atrazine chlorohydrolase gene (trzN) in Arthrobacter sp. DNS10 was investigated in this study. Our results demonstrated that 76.0% of atrazine was degraded in the absence of nicosulfuron after 48h of culture, whereas 63.9, 49.1 and 42.6% was degraded in the presence of 1, 5, and 10 mg/L of nicosulfuron, respectively. Nicosulfuron also induced an increase in the level of intracellular reactive oxygen species (ROS), thereby damaging the cell membrane integrity and inhibiting the growth of the strain DNS10. Flow cytometry analysis revealed that the cell viability of strain DNS10 decreased with an increase in nicosulfuron concentration. The transcription of trzN in strain DNS10 exposed to the three described levels of nicosulfuron was 0.99, 0.72 and 0.52 times, respectively, that without nicosulfuron. In brief, nicosulfuron could inhibit atrazine removal efficiency by strain DNS10 by inducing the over-production of ROS which ultimately enhances the population of membrane-damaged cells, as well as reducing cell viability and trzN transcription. The outcomes of the present study provide new insights into the mechanism of nicosulfuron inhibition on atrazine biodegradation by strain DNS10.

Phosphogypsum (PG) is disposed worldwide in large stacks usually placed in coastal zones, as in the case of Huelva (SW of Spain), where around 100 Mt of PG are stored on the salt marshes of the Tinto River estuary covering a surface of about 1000 ha. This management generates the weathering of PG, and due to its high acidity (pH ≈ 2) and pollutant load can provoke significant emissions into their surroundings. In this work were evaluated by laboratory experiments the effects of pH increase in the behaviour of heavy metals and natural radionuclides during the mixing of phosphogypsum leachates with seawater.The acidic phosphogypsum leachates showed concentrations of heavy metals from two to three orders of magnitude higher than natural continental waters, and natural radionuclides (U-isotopes and ²¹⁰Po) from four to five orders of magnitude higher than unperturbed aquatic systems. Major elements and some heavy metals as Mn, Ni, Cd, As, Sb and Co showed a conservative behaviour during the neutralisation of the leachates with seawater, remaining in the liquid phase, while other ones as Al, Fe, Cr, Zn, Cu, Pb precipitated and/or were adsorbed onto the solid phase. The U-isotopes and ²¹⁰Po showed a clear non-conservative behaviour probably due to coprecipitation/adsorption processes onto the formed precipitates, but while ²¹⁰Po reached a total removal at pH ≈ 7, U- isotopes after a total removal at pH ≈ 5 returned into the liquid phase due to redissolution/desorption processes at near neutral pH.The formed precipitates, mainly composed by iron phosphates particles, showed heavy metal and natural radionuclide concentrations from one to three orders of magnitude higher than unperturbed soils. All these facts demonstrate the serious environmental impact produced by the PG stacks into their surroundings and the urgency of effective restoration measures.

Development of efficient, green and low-cost natural mineral-based reductive materials is promising to remediation of hexavalent chromium(Cr(VI))-contaminated soil. Considering the synergetic effect between pyrite and zerovalent iron (ZVI), an activated pyrite supported ZVI(ZVI/FeS₂) with high reducing activity was developed by ball milling activation of natural pyrite and sulfidation of ZVI. The remediation property of ZVI/FeS₂ for Cr(VI)-contaminated soil was evaluated with different ZVI/FeS₂ dosage, soil-water ratio, initial pH, time and temperature, as well as the stability of Cr. The results showed that ZVI/FeS₂ possessed high reduction activity with soil Cr(VI) removal rate up to 99 % even under alkaline condition, and soil with different pH values eventually converged to neutral after 90 days, indicating that ZVI/FeS₂ has a good self-regulating alkaline ability. The reduction process conformed to Langmuir-Hinshelwood first-order kinetics and was a spontaneous and endothermic process. The lower activation energy of 17.97 kJ mol⁻¹ (usually 60–250 kJ mol⁻¹) indicated that the reduction reaction of Cr(VI) was particularly easy to occur. The speciation change of Cr in soil within 30 days demonstrated that the Cr in the soil was converted from a readily migratable state to a more stable state, where the Fe–Mn oxide bound fraction reached 85.03 % due to the generation of Cr(III)/Fe(III) co-precipitation. The results of long-term stability experiments showed that the leaching concentrations of Cr(VI) and total Cr decreased significantly after the ZVI/FeS₂ treatment and remained stable at very low levels for 180 days. This study provided a sustainable way to fully utilize natural pyrite minerals to obtain iron-bearing reductive materials for feasible, effective and long-term stable immobilization of Cr(VI) in soil.

Intensive aquaculture has largely changed the global phosphorus (P) flow and become one of the main reasons for the eutrophication of global aquatic ecosystem. Artificial planting submerged macrophytes has attracted enormous interest regarding the restoration of eutrophic lakes. However, few large-scale (>80 km²) studies have focused on the restoration of aquatic vegetation in the subtropical lakes, and the mechanism underlying the restrain of sediment P release by macrophytes remains unknown. In this study, field surveys and the diffusive gradients in thin films (DGT) technique were used to elucidate the effects of macrophytes on internal P loading control in a typical eutrophic aquacultural lake. Results showed that half of the P content in overlying water and sediments, particularly dissolved P in overlying water and calcium bound P (Ca–P) in sediment, were removed after restoration. Temperature, as well as dissolved oxygen (DO) and P concentration gradients near the sediment-water interface (SWI) jointly controlled the release of labile P from surface sediments. Submerged macrophytes can effectively inhibit the release of sediment P into the overlying water, which depended on DO concentration in the bottom water. Future restoration projects should focus on the temperature response of submerged macrophytes of different growth forms (especially canopy-forming species) to avoid undesirable restoration effects. Our results complement existing knowledge about submerged macrophytes repairing subtropical P-contaminated lakes and have positive significance for lake restoration by in situ phytoremediation.

Considering that pesticides have been used in Europe for over 70 years, a system for monitoring pesticide residues in EU soils and their effects on soil health is long overdue. In an attempt to address this problem, we tested 340 EU agricultural topsoil samples for multiple pesticide residues. These samples originated from 4 representative EU case study sites (CSS), which covered 3 countries and four of the main EU crops: vegetable and orange production in Spain (S–V and S–O, respectively), grape production in Portugal (P-G), and potato production in the Netherlands (N–P). Soil samples were collected between 2015 and 2018 after harvest or before the start of the growing season, depending on the CSS. Conventional and organic farming results were compared in S–V, S–O and N–P. Soils from conventional farms presented mostly mixtures of pesticide residues, with a maximum of 16 residues/sample. Soils from organic farms had significantly fewer residues, with a maximum of 5 residues/sample. The residues with the highest frequency of detection and the highest content in soil were herbicides: glyphosate and its main metabolite AMPA (P-G, N–P, S–O), and pendimethalin (S–V). Total residue content in soil reached values of 0.8 mg kg⁻¹ for S–V, 2 mg kg⁻¹ for S–O and N–P, and 12 mg kg⁻¹ for P-G. Organic soils presented 70–90% lower residue concentrations than the corresponding conventional soils. There is a severe knowledge gap concerning the effects of the accumulated and complex mixtures of pesticide residues found in soil on soil biota and soil health. Safety benchmarks should be defined and introduced into (soil) legislation as soon as possible. Furthermore, the process of transitioning to organic farming should take into consideration the residue mixtures at the conversion time and their residence time in soil.