International audience | Copper, a priority substance on the EU-Water Framework Directive list, is widely used to protect grapevines against fungus diseases. Many vineyards being located on steep slopes, large amounts of Cu could be discharged in downstream systems by runoff water. The efficiency of stormwater detention basins to retain copper in a vineyard catchment was estimated. Suspended solids, dissolved (Cudiss) and total Cu (Cutot) concentrations were monitored in runoff water, upstream, into and downstream from a detention pond. Mean Cutot concentrations in entering water was 53.6 μg/L whereas it never exceeded 2.4 μg/L in seepage. Cutot concentrations in basin water (>100 μg/L in 24% of the samples) exceeded LC50 values for several aquatic animals. Copper was principally sequestered by reduced compounds in the basin sediments (2/3 of Cutot). Metal sequestration was reversible since sediment resuspension resulted in Cu remobilization. Wind velocity controlled resuspension, explained 70% of Cudiss variability and could help predicting Cu mobilization. Copper in stormwater basin is efficiently retained but can be released during windy events or after dredging.

Bacterial communities in antimony (Sb) polluted soils have been well addressed, whereas the important players fungal communities are far less studied to date. Here, we report different responses of bacterial and fungal communities to Sb contamination and the ecological processes controlling their community assembly. Soil samples in the Xikuangshan mining area were collected and subjected to high through-put sequencing of 16S rRNA and ITS1 to investigate bacterial and fungal communities, respectively, along an Sb gradient. Sb speciation in the soil samples and other physicochemical parameters were analyzed as well. Bacterial communities were dominated by Deltaproteobacteria in the soil with highest Sb concentration, whereas Chloroflexi were dominant in the soil with lowest Sb concentration. Fungal communities in high-Sb soils were predominated by unclassified Fungi, whilst Leotiomycetes were dominant in low-Sb soil samples. Multivariate analysis indicated that Sb, pH and soil texture were the main drivers to strongly impact microbial communities. We further identified Sb-resistant microbial groups via correlation analysis. In total, 18 bacterial amplicon sequence variants (ASVs) were found to potentially involve in biogeochemical cycles such as Sb oxidation, sulfur oxidation or nitrate reduction, whereas 12 fungal ASVs were singled out for potential heavy metal resistance and plant growth promotion. Community assembly analysis revealed that variable selection contributed 100% to bacterial community assembly under acidic or high Sb concentration conditions, whereas homogeneous selection dominated fungal community assembly with a contribution over 78.9%. The community assembly of Sb-resistant microorganisms was mainly controlled by stochastic process. The results offer new insights into microbial ecology in Sb-contaminated soils, especially on the different responses of microbial communities under identical environmental stress and the different ecological processes underlining bacterial and fungal community assembly.

The treatment of contaminants from lignocellulosic biorefinery effluent has recently been identified as a unique challenge. This study focuses on removing phenolic contaminants and polycyclic aromatic hydrocarbons (PAHs) from lignocellulosic biorefinery wastewater (BRW) applying a laccase-assisted approach. Cassava waste was used as a substrate to produce the maximum yield of laccase enzyme (3.9 U/g) from Pleurotus ostreatus. Among the different inducers supplemented, CuSO₄ (0.5 mM) showed an eight-fold increase in enzyme production (30.8 U/g) after 240 h of incubation. The catalytic efficiency of laccase was observed as 128.7 ± 8.47 S⁻¹mM⁻¹ for syringaldazine oxidation at optimum pH 4.0 and 40 °C. Laccase activity was completely inhibited by lead (II) ion, mercury (II) ion, sodium dodecyl sulphate, sodium azide and 1,4 dithiothretiol and induced significantly by manganese (II) ion and rhamnolipid. After treating BRW with laccase, the concentrations of PAHs and phenolic contaminants of 1144 μg/L and 46160 μg/L were reduced to 96 μg/L and 16100 μg/L, respectively. The ability of laccase to effectively degrade PAHs in the presence of different phenolic compounds implies that phenolic contaminants may play a role in PAHs degradation. After 240 h, organic contaminants were removed from BRW in the following order: phenol >2,4-dinitrophenol > 2-methyl-4,6-dinitrophenol > 2,3,4,6-tetrachlorophenol > acenaphthene > fluorine > phenanthrene > fluoranthene > pyrene > anthracene > chrysene > naphthalene > benzo(a)anthracene > benzo(a)pyrene > benzo(b)fluoranthene > pentachlorophenol > indeno(1,2,3-cd)pyrene > benzo(j) fluoranthene > benzo[k]fluoranthène. The multiple contaminant remediation from the BRW by enzymatic method, clearly suggests that the laccase can be used as a bioremediation tool for the treatment of wastewater from various industries.

Fe–N co-doped biochar is recently an emerging carbocatalyst for persulfate activation in situ chemical oxidation (ISCO). However, the involved catalytic mechanisms remain controversial and distinct effects of coexisting water components are still not very clear. Herein, we reported a novel N-doped biochar-coupled crystallized Fe phases composite (Fe@N-BC₈₀₀) as efficient and low-cost peroxydisulfate (PDS) activators to degrade bisphenol A (BPA), and the underlying influencing mechanism of coexisting inorganic anions (IA) and humic constituent. Due to the formation of graphitized nanosheets with high defects (AI index>0.5, ID/IG = 1.02), Fe@N-BC₈₀₀ exhibited 2.039, 5.536, 8.646, and 23.154-fold higher PDS catalytic activity than that of Fe@N-BC₆₀₀, Fe@N-BC₄₀₀, N-BC, BC. Unlike radical pathway driven by carbonyl group and pyrrolic N of low/mid-temperature Fe@N–BCs. The defective graphitized nanosheets and Fe-Nx acted separately as electron transfer and radical pathway active sites of Fe@N-BC₈₀₀, where π-π sorption assisted with pyrrolic N and pore-filling facilitated BPA degradation. The strong inhibitory effects of PO₄³⁻ and NO₂⁻ were ascribed to competitive adsorption of phosphate (61.11 mg g⁻¹) and nitrate (23.99 mg g⁻¹) on Fe@N-BC₈₀₀ via electrostatic attraction and hydrogen bonding. In contrast, HA competed for the pyrrolic-N site and hindered electron delivery. Moreover, BPA oxidation pathways initiated by secondary free radicals were proposed. The study facilitates a thorough understanding of the intrinsic properties of designed biochar and contributes new insights into the fate of degradation byproducts formed from ISCO treatment of micropollutants.

We investigated the biological response of soluble organic fraction (SOF) and water-soluble fraction (WSF) extracted from particulate matter (PM) emitted by an automotive diesel engine operating in a representative urban driving condition. The engine was fueled with ultra-low sulfur diesel (ULSD), and its binary blends by volume with 13% of butanol (Bu13), and with hydrotreated vegetable oil (HVO) at 13% (HVO13) and 20% (HVO20). Cytotoxicity, genotoxicity, oxidative DNA damage and ecotoxicity tests were carried out, and 16 polycyclic aromatic hydrocarbons (PAH) expressed as tbenzo(a)pyrene total toxicity equivalent (BaP-TEQ) were also analyzed. The Hepatocarcinoma epithelial cell line (HepG2) was exposed to SOF for 24 h and analyzed using comet assay, with the inclusion of formamidopyrimidine DNA glycosylase (FPG) and endonuclease III (Endo III) to recognize oxidized DNA bases. The WSF was evaluated through acute ecotoxicity tests with the aquatic microcrustacean Daphnia pulex (D. Pulex). Results showed that there was no cytotoxic activity for all tested SOF concentrations. Genotoxic responses by all the SOF samples were at same level, except for the HVO13 which was weaker in the absence of the enzymes. The addition of the FPG and Endo III enzymes resulted in a significant increase in the comet tail, indicating that the DNA damage from SOF for all tested fuel blends involves oxidative damage including a higher level of oxidized purines for ULSD and Bu13 in comparison with HVO blends, but the oxidized pyrimidines for HVO blends were slightly higher compared to Bu13. The WSF did not show acute ecotoxicity for any of the fuels. Unlike other samples, Bu13-derived particles significantly increase the BaP-TEQ. The contribution to the genotoxic activity and oxidative DNA from SOF was not correlated to BaP-TEQ, which means that the biological activity of PM might be affected also by other toxic compounds present in particulate phase.

Effects of human activities on atmospheric nitrate (NO₃⁻) formation remain unclear, though the knowledge is critical for improving atmospheric chemistry models and nitrogen deposition reduction strategies. A potentially useful way to explore this is to compare NO₃⁻ oxidation processes in urban and rural atmospheres based upon the oxygen stable isotope composition of NO₃⁻ (Δ¹⁷O–NO₃⁻). Here we compared the Δ¹⁷O–NO₃⁻ from three-years of daily-based bulk deposition in urban (Shenyang) and forested rural sites (Qingyuan) in northeast China and quantified the relative contributions of different formation pathways based on the SIAR model. Our results showed that the Δ¹⁷O in Qiangyuan (26.2 ± 3.3‰) is significantly higher (p < 0.001) than in Shenyang (24.0 ± 4.0‰), and significantly higher in winter (Shenyang: 26.1 ± 6.7‰, Qingyuan: 29.6 ± 2.5‰) than in summer (Shenyang: 22.7 ± 2.9‰, Qingyuan: 23.8 ± 2.4‰) in both sites. The lower values in the urban site are linked with conditions that favored a higher relative contribution of nitrogen dioxide reaction with OH pathway (0.76-0.91) than in rural site (0.47-0.62), which should be induced by different levels of human activities in the two sites. The seasonal variations of Δ¹⁷O–NO₃⁻ in both sites are explained by a higher relative contribution of ozone-mediated oxidation chemistry and unfavorable conditions for the OH pathway during winter relative to summer, which is affected by human activities and seasonal meteorological condition change. Based on Δ¹⁷O, wintertime conditions led to a contribution of O₃ related pathways (NO₃ + DMS/HC and N₂O₅ hydrolysis) of 0.63 in Qingyuan and 0.42 in Shenyang, while summertime conditions led to 0.15 in Qingyuan and 0.05 in Shenyang. Our comparative study on Δ¹⁷O–NO₃⁻ between urban and rural sites reveals different anthropogenic effects on nitrate formation processes on spatial and temporal scales, illustrating different responses of reactive nitrogen chemistry to changes in human activities.

The effectiveness and feasibility of the three biochar materials for remediation of arsenic (As) and lead (Pb) contaminated soil were explored in this study. Significant reduction of bioaccessibility and migration risks of both heavy metals have been explained mechanistically by incubation, column experiments and numerical simulation. Langmuir equation fitted As and Pb sorption isotherms better in the control and biochar (BC) amended soils, while Freundlich model was more suitable for iron modified biochar (Fe-BC) and sulfur/iron modified biochar (S/Fe-BC) amended soils, indicating that modified biochar promoted chemical adsorption process for As and Pb. For the three biochar materials, S/Fe-BC showed the best effects on reducing the bioavailability of As and Pb, with a decrease of 40.42%–64.21%. The reduction in bioaccessibility by metal portioning into available and non-available fractions was better for illustrating the mechanisms including adsorption, precipitation/coprecipitation and As(III) oxidation behind S/Fe-BC efficacy. Moreover, S/Fe-BC can effectively inhibit the leaching behavior of As and Pb under acid rain, which increased by 99.89% and 90.18%, respectively, compared with the control. The HYDRUS-1D modeling indicated that S/Fe-BC could continuously treat As (100 mg/L) and Pb (1000 mg/L) contaminated water for 16.22 years and 40.86 years, respectively, and ensure the groundwater quality criteria being met. Based on these insights, we believe that our study will provide meaningful information about the potentials of biochar derived materials for soil heavy metals’ remediation.

The coexistence of nitrate and endocrine substances (EDCs) in groundwater is of global concern. Herein, an efficient and stable polypyrrole@corn cob (PPy@Corn cob) bioreactor immobilized with Zoogloea sp. was designed for the simultaneous removal of 17β-estradiol (E2), nitrate and Mn(II). After 225 days of continuous operation, the optimal operating parameters and enhanced removal mechanism were explored, also the long-term toxicity and microbial communities response mechanisms under E2 stress were comprehensively evaluated. The results showed that the removal efficiencies of E2, nitrate, and Mn(II) were 84.21, 82.96, and 47.91%, respectively, at the optimal operating conditions with hydraulic retention time (HRT) of 8 h, pH of 6.5 and Mn(II) concentration of 20 mg L⁻¹. Further increased of initial E2 (2 and 3 mg L⁻¹) resulted in the inhibiting effect of denitrification and manganese oxidation, but excellent E2 removal efficiencies maintained, which were associated with the formation and continuous accumulation of biomanganese oxides (BMO). Characterization analysis of biological precipitation demonstrated that adsorption and redox conversion on the BMO surface played key roles in the removal of E2. In addition, different levels of E2 exposure are decisive factors in community evolution, and bioaugmented bacterial communities with Zoogloea as the core group can dynamically adapt to E2 stress. This study offers the possibility to better utilize microbial metabolism and to advance opportunities that depend on microbial physiology and material characterization applications.

In recent years, the naturally high background value region of Cd derived from the weathering of carbonate has received wide attention. Due to the significant difference in soil Cd content and bioavailability among different parent materials, the previous land classification scheme based on total soil Cd content as the classification standard, has certain shortcomings. This study aims to explore the factors influencing soil Cd bioavailability in typical karst areas of Guilin and to suggest a scientific and effective farmland use management plan based on the prediction model. A total of 9393 and 8883 topsoil samples were collected from karst and non-karst areas, respectively. Meanwhile, 149 and 145 rice samples were collected together with rhizosphere soil in karst and non-karst areas, respectively. The results showed that the higher CaO level in the karst area was a key factor leading to elevated soil pH value. Although Cd was highly enriched in karst soils, the higher pH value and adsorption of Mn oxidation inhibited Cd mobility in soils. Conversely, the Cd content in non-karst soils was lower, whereas the Cd level in rice grains was higher. To select the optimal prediction model based on the correlation between Cd bioaccumulation factors and geochemical parameters of soil, artificial neural network (ANN) and linear regression prediction models were established in this study. The ANN prediction model was more accurate than the traditional linear regression model according to the evaluation parameters of the test set. Furthermore, a new land classification scheme based on an ANN prediction model and soil Cd concentration is proposed in this study, making full use of the spatial resources of farmland to ensure safe rice consumption.

This study investigated catalytic ozone oxidation using a sawdust char (SDW) catalyst to remove hazardous toluene emitted from the chemical industry. The catalyst properties were analyzed by proximate, ultimate, nitrogen adsorption-desorption isotherms, Fourier-transform infrared, and X-ray photoelectron spectroscopy analyses. In addition, hydrogen-temperature programmed reduction experiments were conducted to analyze the catalyst properties. The specific area and formation of micropores of SDC were improved by applying KOH treatment. MnOx/SDC-K3 exhibited a higher toluene removal efficiency of 89.7% after 100 min than MnOx supported on activated carbon (MnOx/AC) with a removal efficiency of 6.6%. The higher (Oₐdₛ (adsorbed oxygen)+Oᵥ(vacancy oxygen))/OL (lattice oxygen) and Mn³⁺/Mn⁴⁺ ratios of MnOx/SDC-K3 than those of MnOx/AC seemed to be important for the catalytic oxidation of toluene.