Effects of COVID-19 on coastal and marine environments: Aggravated microplastic pollution, improved air quality, and future perspective.

The COVID-19 pandemic during 2020-2023 has wrought adverse impacts on coastal and marine environments. This study conducts a comprehensive review of the collateral effects of COVID-19 on these ecosystems through literature review and bibliometric analysis. According to the output and citation analysis of these publications, researchers from the coastal countries in Asia, Europe, and America payed more attentions to this environmental issue than other continents. Specifically, India, China, and USA were the top three countries in the publications, with the proportion of 19.55%, 18.99%, and 12.01%, respectively. The COVID-19 pandemic significantly aggravated the plastic and microplastic pollution in coastal and marine environments by explosive production and unproper management of personal protective equipment (PPE). During the pandemic, the estimated mismanaged PPE waste ranged from 16.50 t/yr in Sweden to 250,371.39 t/yr in Indonesia. In addition, the PPE density ranged from 1.13 × 10-5 item/m2 to 2.79 item/m2 in the coastal regions worldwide, showing significant geographical variations. Besides, the emerging contaminants released from PPE into the coastal and marine environments cannot be neglected. The positive influence was that the COVID-19 lockdown worldwide reduced the release of air pollutants (e.g., fine particulate matter, NO2, CO, and SO2) and improved the air quality. The study also analyzed the relationships between sustainable development goals (SDGs) and the publications and revealed the dynamic changes of SDGs in different periods the COVID-19 pandemic. In conclusion, the air was cleaner due to the lockdown, but the coastal and marine contamination of plastic, microplastic, and emerging contaminants got worse during the COVID-19 pandemic. Last but not least, the study proposed four strategies to deal with the coastal and marine pollution caused by COVID-19, which were regular marine monitoring, performance of risk assessment, effective regulation of plastic wastes, and close international cooperation.

Efficient roxarsone degradation by low-dose peroxymonosulfate with the activation of recycling iron-base composite material: Critical role of electron transfer.

Pollutant degradation via electron transfer based on advanced oxidation processes (AOPs) provides an economical and energy-efficient method for pollution control. In this study, an iron-rich waste, heating pad waste (HPW), was recycled as a raw material, and a strong magnetic catalyst (Fe-HPW) was synthesized at high temperature (900 °C). Results showed that in the constructed Fe-HPW/PMS system, effective roxarsone (ROX) degradation and TOC removal (72.54%) were achieved at a low-dose of oxidant (PMS, 0.05 mM) and catalyst (Fe-HPW, 0.05 g L-1), the ratio of PMS to ROX was only 2.5:1. In addition, the released inorganic arsenic was effectively removed from the solution. The analysis of the experimental results showed that ROX was effectively degraded by forming PMS/catalyst surface complexes (Fe-HPW-PMS*) to mediate electron transfer in the Fe-HPW/PMS system. Besides, this system performed effective ROX degradation over a wide pH range (pH=3-9) and showed high resistance to different water parameters. Overall, this study not only provides a new direction for the recycling application of HPW but also re-emphasizes the neglected nonradical pathway in advanced oxidation processes.

The composition and differences of antimony isotopic in sediments affected by the world's largest antimony deposit zone.

Antimony (Sb) isotopic fingerprinting is a novel technique for stable metal isotope analysis, but the use of this technique is still limited, especially in sediments. In this study, the world's most important Sb mineralization belt (the Xikuangshan mineralization belt) was taken as the research object and the Sb isotopic composition and Sb enrichment characteristics in the sediments of water systems from different Sb mining areas located in the Zijiang River (ZR) Basin were systematically studied. The results showed that the ε123Sb values in the sediments of the ZR and its tributaries, such as those near the Longshan Sb-Au mine, the Xikuangshan Sb mine, and the Zhazixi Sb mine, were 0.50‒3.13 ε, 2.31‒3.99 ε, 3.12‒5.63 ε and 1.14‒2.91 ε, respectively, and there were obvious changes in Sb isotopic composition. Antimony was mainly enriched in the sediments due to anthropogenic sources. Dilution of Sb along the river and adsorption of Sb to Al-Fe oxides in the sediment did not lead to obvious Sb isotopic fractionation in the sediment, indicating that the Sb isotopic signature was conserved during transport along the river. The Sb isotopic signatures measured in mine-affected streams may have differed from those in the original Sb ore, and further investigation of Sb isotopic fingerprints from other possible sources and unknown geochemical processes is needed. This study reveals that the apparent differences in ε123Sb values across regions make Sb isotopic analysis a potentially suitable tool for tracing Sb sources and biogeochemical processes in the environment.

Comprehensive insight into mercury contamination in atmospheric, terrestrial and aquatic ecosystems surrounding a typical antimony-coal mining district.

This study comprehensively investigated mercury (Hg) contents of various environmental compartments in a typical antimony-coal mining area with intensive industrial activities over the past 120 years to analyze Hg environmental behaviors and evaluate Hg risks. The total mercury (THg) contents in river water, sediments, soils, PM10, dust falls, vegetables and corns were 1.16 ± 0.63 µg/L, 2.01 ± 1.64 mg/kg, 1.87 ± 3.88 mg/kg, 7.87 ± 18.68 ng/m3, 13.01 ± 14.53 mg/kg, 0.30 ± 0.34 mg/kg and 3.11 ± 0.51 µg/kg, respectively. The δ202Hg values in soils and dust falls were - 1.58 ∼ 0.12‰ and 0.25 ∼ 0.30‰, respectively. Environmental samples affected by industrial activities in the Xikuangshan (XKS) presented higher THg and δ202Hg values. Binary mixing model proved that atmospheric deposition with considerable Hg deposition flux (0.44 ∼ 6.40, 3.12 ± 2.20 mg/m2/y) in the XKS significantly contributed to Hg accumulations on surface soils. Compared with soils, sediments with more frequent paths and higher burst probabilities presented higher dynamic Hg risks. Children were faced higher health risk of multiple Hg exposure than adults. Furthermore, the health risk of THg by consuming leaf vegetables deserved more attention. These findings provided scientific basis for managing Hg contamination.

Fine particle contents in sediment drive silica transport and deposition to the estuary in the turbid river basin.

Changes in riverine sediment transport are an important part of land-sea geochemical cycling and further impact geochemical element fluxes in turbid rivers. However, as a vital nutrient element supporting primary productivity, silica mobilization from drainage in turbid rivers is overlooked. The turbid Yellow River has a strong ability to adsorb reactive silica, thereby exerting a substantial impact on the estuarine deposition of silica. Through an integration of monitoring databases, field sampling and historical hydrological data, we concluded that riverine fine particles control the exchangeable silica in the river and its estuary under soil erosion. Indoor simulation further revealed that the adsorbed content of exchangeable silica (ex-Si) in fine sediment constituted 35 % of total sediment matter. In addition, the transport of phosphorus and ex-Si was jointly regulated by fine sediment in global fluvial sediment transport, thereby exerting additional influence on the trophic structure of estuarine ecosystems. Against the backdrop of sediment budget deficit in the estuary, the heightened content of fine particles is depleting the silica storage from estuarine sediments.

Occurrence, bioaccumulation and trophodynamics of organophosphate esters in the marine biota web of Laizhou Bay, Bohai Sea.

The trophodynamic of organophosphate esters (OPEs) has not been known well despite their widespread occurrence in the aquatic environments. In this study, ten species of crustacean, seven species of mollusk, and 22 species of fish were collected in the Laizhou Bay (LZB) to examine the occurrence, bioaccumulation, and trophic transfer, and health risk of eight traditional OPEs and three emerging oligomeric OPEs. The results showed that total concentration of OPEs was 2.04 to 28.6 ng g-1 ww in the muscle of crustacean, mollusk, and fish and 2.62 to 60.6 ng g-1 ww in the fish gill. Chlorinated OPEs averagely contributed to over 85% of total OPEs while oligomeric OPEs averagely accounted for approximate 4%. The average log apparent bioaccumulation factor (ABAF) ranged from - 0.4 L kg-1 ww for triethyl phosphate to 2.4 L kg-1 ww for resorcinol-bis (diphenyl) phosphate. Apparent trophic magnification factors (ATMF) of individual OPE were generally less than 1, demonstrating the biodilution effect of the OPEs in the organism web of LZB. Additionally, the log ABAF and ATMF of OPEs were significantly positively correlated to their log Kow but negatively correlated to their biotransformation rate constant (BRC). Therefore, the OPEs with high Kow and low BRC tend to more accumulate in the marine organisms. The health risks associated with OPEs through the consumption of the seafood from the bay were low, even at high exposure scenario.

Occurrence, removal efficiency, and emission of antibiotics in the sewage treatment plants of a low-urbanized basin in China and their impact on the receiving water.

Sewage treatment plants (STPs) are primary sources of antibiotics in aquatic environments. However, limited research has been conducted on antibiotic attenuation in STPs and their downstream waters in low-urbanized areas. This study analyzed 15 antibiotics in the STP sewage and river water in the Zijiang River basin to quantify antibiotic transport and attenuation in the STPs and downstream. The results showed that 14 target antibiotics, except leucomycin, were detected in the STP sewage, dominated by amoxicillin (AMOX), ofloxacin, and roxithromycin. The total antibiotic concentration in the influent and effluent ranged from 158 to 1025 ng/L and 99.9 to 411 ng/L, respectively. The removal efficiency of total antibiotics ranged from 54.7 % to 75.7 % and was significantly correlated with total antibiotic concentration in the influent. The antibiotic emission from STPs into rivers was 78 kg/yr and 4.6 g/km2yr in the Zijiang River basin. The total antibiotic concentration downstream of the STP downstream was 23.6 to 213 ng/L and was significantly negatively correlated with the transport distance away from the STP outlets. Antibiotics may pose a high ecological risk to algae and low ecological risk to fish in the basin. The risk of AMOX and ciprofloxacin resistance for organisms in the basin was estimated to be moderate. This study established antibiotic removal and attenuation models in STPs and their downstream regions in a low-urbanized basin, which is important for simulating antibiotic transport in STPs and rivers worldwide.

Mechanochemical degradation performance of lindane in different types of soils: The effects of soil properties and elemental components.

Although mechanochemical remediation of organic-contaminated soil has received substantial attention in recent years, the effects of soil properties on soil remediation performance are not clear. In this work, the properties and elemental components of 16 soils were tested, and the mechanochemical degradation performance of lindane in these soils was investigated through experiments. Most importantly, the relationships between soil variables and the mechanochemical degradation rates of lindane in the additive-free and CaO systems were elucidated. The results showed that the mechanochemical degradation efficiencies of lindane in the 16 soils were significantly different without additives, with a range of 31.0 %-97.2 % after 4 h. The mechanochemical degradation rates of lindane in the 16 soils varied from 0.7 h-1 to 15 h-1 after the addition of 9 % CaO. Correlation analysis, redundancy analysis and the partial least squares path modeling results clearly showed that the main factors affecting the reaction rate (k1) without additives were organic matter (-) > clay (+) > bound water (-) > Si (+). After the addition of 9 % CaO, the order in which the main factors affected the reaction rate (k2) was organic matter (-) > bound water (-) > Ti/Fe/Al (-) > pH (+) > clay (+). The established and corrected multiple nonlinear regression equations can be used to accurately predict the mechanochemical degradation performance of hexachlorocyclohexanes in actual soils with and without additives.

Accelerated export and transportation of heavy metals in watersheds under high geological backgrounds.

The geological background level of metals plays a major role in mineral distribution and watershed diffuse heavy metal (HM) pollution. In this study, field research and a distributed hydrological model were used to analyze the distribution, sources, and pollution risk of watershed HMs in sediments with high geological HM backgrounds. Study showed that the mineral distribution and landcover promoted the transport differences of watershed HMs from upstream to the estuary. And the main sources of Co, Ni, and V in the estuarine sediments were natural sources. Sources of Pb and Zn were dominated by anthropogenic sources, accounting for 76% and 64% of their respective totals. The overall ecological risk of anthropogenically sourced HMs was dominated by Pb (46.6%), while the contributions of Co and Ni were also relatively high, accounting for 35.70% and 33.40%. Moreover, redundancy analysis showed that HM variations in the sediments were most sensitive to soil erosion and mineralizing rock distribution. The spatial patterns of watershed HMs from natural sources were significantly influenced by P loading, precipitation, and forest distribution. This combination of experiments and model improves the understanding of watershed HM variation and provides a new perspective for formulating effective watershed HM management strategies.

Socioeconomic and seasonal effects on spatiotemporal trends in estrogen occurrence and ecological risk within a river across low-urbanized and high-husbandry landscapes.

Estrogen pollution is a persistent issue in rivers. This study investigated the occurrence, spatiotemporal variation mechanisms, sources, and ecological risks of estrone (E1), 17ß-estradiol (E2), estriol (E3), 17α-ethinylestradiol (EE2), diethylstilbestrol (DES), and bisphenol-A (BPA) in the waters of the Zijiang River, a tributary of the middle Yangtze River. The results revealed elevated detection frequencies and estrogen concentrations in the dry season compared to the wet season, mainly due to the precipitation dilution effect. Total estrogen concentration ranged from 21.2 to 97.5 ng/L in the dry season, which was significantly correlated to spatial distributions of animal husbandry and population. Among the estrogens studied in the river, E2, BPA, and EE2 were predominant. The collective sources of E1, E2, E3, and EE2 were traced back to human and husbandry excrement, whereas BPA emitted from daily life products, contributing to 55.5% and 42.7% of the total estrogen concentration, respectively. Particularly, the average and median E1, E2, and EE2 concentrations in the river exceeded the environmental quality standards of the European Union. The total estrogenic activity dominated by EE2 exceeded the 1 ng E2/L threshold, with levels exceeding 10 ng E2/L during the dry season. The risk quotients exhibited a high ecological risk of E1 and EE2 to fish and a moderate to high ecological risk of E1 to crustaceans, EE2 to mollusks, and E2 to fish. Therefore, E1, E2, and EE2 pollution of the river may lead to both high estrogenic potency and moderate or high ecological risk; thus, they should be considered priority pollutants in the river. These results yield valuable insights into the spatiotemporal change mechanisms, sources, and ecological risks of estrogens in river water of low-urbanization and rural watersheds.

Distribution heterogeneity of sediment bacterial community in the river-lake system impacted by nonferrous metal mines: Diversity, composition and co-occurrence patterns.

Metal(loid) pollution caused by mining activities can affect microbial communities. However, knowledge of the diversity, composition, and co-occurrence patterns of bacterial communities in aquatic systems impacted by nonferrous metal mines. Here, the metal(loid) contents and bacterial communities in sediments from the Zijiang River (tributary to mainstream) to Dongting Lake were investigated by geochemical and molecular biology methods. The results indicated that the river sediments had lower pH and higher ecological risk of metal(loid)s than the lake sediment. The diversity and composition of bacterial communities in river sediments significantly (p < 0.05) differed from those in lake sediments, showing distributional heterogeneity. The biomarkers of tributary, mainstream, and lake sediments were mainly members of Deltaproteobacteria, Firmicutes, and Nitrospirae, respectively, reflecting species sorting in different habitats. Multivariate statistical analysis demonstrated that total and bioavailable Sb, As, and Zn were positively correlated with bacterial community richness. pH, TOC, TN, and Zn were crucial factors in shaping the distribution difference of bacterial communities. Environment-bacteria network analysis indicated that pH, SO42-, and total and bioavailable As and Sb greatly influenced the bacterial composition at the genus level. Bacteria-bacteria network analysis manifested that the co-occurrence network in mainstream sediments with a higher risk of metal(loid) pollution exhibited higher modularity and connectivity, which might be the survival mechanism for bacterial communities adapted to metal(loid) pollution. This study can provide a theoretical basis for understanding the ecological status of aquatic systems.

Discharge dynamics of agricultural diffuse pollution under different rainfall patterns in the middle Yangtze river.

Rainfall plays a crucial role in influencing the loss of agricultural diffuse pollution. The middle Yangtze River region is well-know for its humid climate and numerous agricultural activities. Thus, this study quantitatively analyzed the concentration and distribution of nitrogen (N) and phosphorus (P) load and loss in a major tributary of the middle Yangtze River under different rainfall patterns by using sampling analysis and SWAT model simulation. The total nitrogen (TN) and nitrate-nitrogen (NO3-) concentrations were 1.604-3.574 and 0.830-2.556 mg/L, respectively. The total phosphorous (TP) and Soluble Reactive Phosphorus (SRP) were 2-148 and 2-104 µg/L, respectively. The modeling results demonstrated that higher rainfall intensity led to greater load and loss flux of diffuse pollutant at the outlet. Organic nitrogen (ORGN) is the main nitrogen form transported from the subbasin to the reach, while organic phosphorus (ORGP) and inorganic phosphorus (INORGP) were transported at similar amounts. Under the condition of conventional rainfall, the outlet reaches mainly transported NO3-, and ORGN gradually increased when rainstorm events occurred. The ratio of INORGP to ORGP was relatively stable. During extreme rainfall event, rainfall is the dominant element of agricultural diffuse pollution. A strong positive correlation exists between rainfall intensity and pollution loss during rainstorms. Storm rain events were the main source of TN and TP losses. Few storm rain days generated pollutants that accounted for a large proportion of the total loss, and their impact on TP loss was significantly greater than that of TN. The influence of storm rain on TN is mainly the increase in runoff, while TP is sensitive to the runoff and sediment transport promoted by rainfall. By setting different precipitation scenarios, it was confirmed that under the same rainfall amount, short-term storm rain has the most significant impact on the TN load, whereas TP load may be influenced more by the combined effects of rainfall duration and intensity. Therefore, to reduce the impact of agricultural diffuse pollution, it is important to take targeted measures for the rainstorm days.

Monte Carlo simulation and delayed geochemical hazard revealed the contamination and risk of arsenic in natural water sources.

Due to its ubiquity and carcinogenicity, the geochemical behavior and health risks of arsenic (As) have been a research focus worldwide. A comprehensive investigation was conducted on the contamination and ecological and health risks of As in the Zijiang River (ZR)-a natural water source. The concentration ranges of As were separately 1.36-6.23 µg/L, 11.42-74.53 mg/kg, and 1.26-130.68 µg/L in surface waters (dissolved), sediments, and pore waters. The concentrations of As in the midstream pore waters and sediments were relatively high, which was related to mining, dam interception, and sediment resuspension. The Monte Carlo simulation results showed that the occurrence probability of As contamination and static risk in sediments was low, however, in the midstream, the secondary risk caused by the release of As should be given more consideration. In the sediments, the transformation paths and the dynamic risk of As were explored based on the delayed geochemical hazard model, showing that there was a probability of a potential burst of 26.47% - 55.88% in the sediments of the ZR. Although at the detected surface waters, the total risk of the noncarcinogenicity and carcinogenicity of As were low, overall adults have lower health risks than children, and As exposure in children should be of concern. This study complements the further understanding of the geochemical behavior of arsenic, which can be extended to other toxic metal(loid)s.

Occurrence, distribution, and potential ecological risks of antibiotics in a seasonal freeze-thaw basin.

Antibiotics have gained increasing attention as pharmaceuticals widely existing in human society. Under low temperature conditions, antibiotics tend to have higher environmental persistence, which poses a potential threat to ecological environment, but research on antibiotics in low-temperature basins is still lacking. Therefore, for investigating occurrence, spatio-temporal distributions, and ecological risks of antibiotics in a seasonal freeze-thaw basin, rivers in Tumen River basin were selected and sampled, including 25 samples during the river-freezing season and 27 samples during the non-freezing season. Overall, climate characteristics of different latitudes and renewal frequency of antibiotics are important factors that lead to diversity of antibiotics in basins. Eleven target antibiotics were detected and their average concentrations during the river-freezing season (0.83-27.5 ng L-1) were lower than that during the non-freezing season (2.80-45.30 ng L-1), severely impacted by river flow, ice sealed-melting, and local feeding practices. In addition, total antibiotic concentrations are usually highest in downstream areas of human settlements, receiving input from husbandry and sewage, respectively. Through ecological risk assessment, norfloxacin and amoxicillin posed high risks to algae, which were identified as high-risk pollutants in basin.

Tracking the multiple Hg sources in sediments in a typical river-lake basin by isotope compositions and mixing models.

In this study, total mercury (THg) contents and Hg isotope compositions in sediments were investigated in the Lianxi River, Zijiang River and South Dongting Lake to identify and quantify multiple Hg sources and evaluate the Hg environmental processes. The THg contents, δ202Hg and Δ199Hg values in sediments were 48.22 ∼ 4284.32 µg/kg, - 1.33 ∼ 0.04‰ and - 0.25 ∼ 0.03‰, respectively. Relatively distinct Hg isotope characteristics of sediments were presented in the Lianxi River, Zijiang River and South Dongting Lake, indicating the dominant Hg sources considerably varied in these regions. Source apportionment based on MixSIAR proved that Hg in sediments mainly originated from industrial activities, and the ternary mixing model concluded non-ferrous metal smelting was the dominant industrial Hg contributor in the Lianxi River. Compared with the Lianxi River, the relative contribution of Hg in sediments from industrial activities significantly decreased, while the relative contributions of Hg from background releases significantly increased in the Zijiang River and South Dongting Lake. Nonetheless, the contribution of industrial Hg in this study area deserves more attention. These results are conducive to further manage Hg pollution.

Peroxymonosulfate assisted mechanochemical remediation of high concentration DDTs contaminated soil.

DDTs (DDT and its metabolites) contaminated sites urgently need to be treated efficiently and greenly. In this study, a horizontal planetary mechanochemical method with co-milling additives was developed aiming at efficiently degrading high-concentration DDTs in historical contaminated soil (∼7500 mg/kg). Peroxymonosulfate (PMS) was firstly used to the mechanochemical degradation of DDTs in historical contaminated soil, with a degradation efficiency of over 95% after 1 h of milling under the optimal milling conditions (CR = 30:1, r = 500 rpm, R = 1:4). Mechanism study indicated that DDTs in soil were partially dechlorinated and mineralized. The main products formed might be chlorinated aliphatic hydrocarbons, which need further treatment by ball milling or other methods. Under the action of mechanical energy, PMS could oxidize DDTs in soil through non-radical way rather than common radical way. Then, a comprehensive assessment of this remediation method was conducted by analyzing the changes in soil properties and acute biotoxicity after ball milling. Although PMS had a great performance on the degradation of DDTs, especially p, p'-DDE, it would cause the acidification and salinization of soil. Therefore, further pH adjustment and desalination treatment were suggested to reduce the negative impacts. This work successfully presents a practical approach to mechanochemical remediation of DDTs contaminated sites.

Mechanistic insights into Sb(III) and Fe(II) co-oxidation by oxygen and hydrogen peroxide: Dominant reactive oxygen species and roles of organic ligands.

Sole O2 or H2O2 oxidant hardly oxidize Sb(III) on a time scale of hours to days, but Sb(III) oxidation can simultaneously occur in Fe(II) oxidation by O2 and H2O2 due to the generation of reactive oxygen species (ROS). However, Sb(III) and Fe(II) co-oxidation mechanisms regarding the dominant ROS and effects of organic ligands require further elucidation. Herein, the co-oxidation of Sb(III) and Fe(II) by O2 and H2O2 was studied in detail. The results indicated that increasing the pH significantly increased Sb(III) and Fe(II) oxidation rates during Fe(II) oxygenation, while the highest Sb(III) oxidation rate and oxidation efficiency was obtained at pH 3 with H2O2 as the oxidant. HCO3- and H2PO4-anions exerted different effects on Sb(III) oxidation in Fe(II) oxidation processes by O2 and H2O2. In addition, Fe(II) complexed with organic ligands could improve Sb(III) oxidation rates by 1 to 4 orders of magnitude mainly due to more ROS production. Moreover, quenching experiments combined with the PMSO probe demonstrated that .OH was the main ROS at acidic pH, whereas Fe(IV) played a key role in Sb(III) oxidation at near-neutral pH. In particular, the steady-state concentration of Fe(IV) ([Fe(IV)]ss) and kFe(IV)/Sb(III) were determined to be 1.66×10-9 M and 2.57×105 M-1 s-1, respectively. Overall, these findings help to better understand the geochemical cycling and fate of Sb in Fe(II)- and DOM-rich subsurface environments undergoing redox fluctuations and are conductive to developing Fenton reactions for the in-situ remediation of Sb(III)-contaminated environments.

Mechanochemical remediation of lindane-contaminated soils assisted by CaO: Performance, mechanism and overall assessment.

Soil contamination caused by persistent organic pollutants (POPs) has been a worldwide concern for decades. With lindane-contaminated soil as the target, a mechanochemical method assisted by CaO was comprehensively evaluated in terms of its remediation performance, degradation mechanism and overall assessment. The mechanochemical degradation performance of lindane in cinnamon soil or kaolin was determined under different additives, lindane concentrations and milling conditions. 2,2-Diphenyl-1-(2,4,6-trinitrophenyl) hydrazinyl free radical (DPPH•) and electron spin resonance (ESR) tests evidenced that the degradation of lindane in soil was caused mainly by the mechanical activation of CaO to produce free electrons (e-) and the alkalinity of the generated Ca(OH)2. Dehydrochlorination or dechlorination by elimination, alkaline hydrolysis, hydrogenolysis and the subsequent carbonization were the main degradation pathways of lindane in soil. The main final products included monochlorobenzene, carbon substances and methane. The mechanochemical method with CaO was proved to also efficiently degrade lindane in three other soils and other hexachlorocyclohexane isomers and POPs in soil. The soil properties and soil toxicity after remediation were assessed. This work presents a relatively clear discussion of various aspects of the mechanochemical remediation of lindane-contaminated soil assisted by CaO.

Riverine antibiotic occurrence and potential ecological risks in a low-urbanized and rural basin of the middle Yangtze River: Socioeconomic, land use, and seasonal effects.

This study firstly investigated the effects of season, land use, and socioeconomic on the spatiotemporal changes of riverine antibiotic concentrations in a low urbanized and rural watershed. In the dry and wet seasons, water samples were collected and analyzed for 15 antibiotics. The results indicated that 14 antibiotics, excluding leucomycin, were detected. Monsoon led to significantly lower total antibiotic concentrations in the wet season (22.0ngL-1) than in the dry season (51.2ngL-1). Total antibiotic concentrations were dominated by amoxicillin (below limit of detection (

Industrial impacts on vanadium contamination in sediments of Chinese rivers and bays.

Vanadium, like many trace metals, is persistent and detrimental to ecosystems at elevated concentrations. Likewise, it is versatile, functional, and used in many industries. Jiaozhou Bay (JZB) and Laizhou Bay (LZB) are valuable coastal ecosystems in China coexisting with several of these vanadium-related industries; however, limited studies have been conducted regarding vanadium occurrence, distribution, sources and risks in sediments. 208 surface sediment samples were collected from rivers and bays over two years and analyzed using inductively coupled plasma optical emission spectrometry. Overall, sediments near vanadium-related industries have significantly higher vanadium concentrations than those near traditional industries, with 30.3% and 22.9% higher average concentrations of vanadium in sediments of JZB and LZB, respectively. Vanadium accumulation at LZB is positively correlated with fine sediment, oxides (e.g., Fe, Ti, Mn), and organic matter content, while temporal changes in parts of JZB highlight the impacts of oxides, pH, and redox conditions on its accumulation. After geochemical normalization, the concentrations in marine samples from LZB showed slightly polluted sediments under the Modified Nemerow pollution index. Likewise, the elevated concentrations of vanadium in JZB, rivers and bay, were classified as slightly polluted and correlated with anthropogenic activities, such as the coal and petrochemical industries. Temporal changes indicated higher enrichments in 2019. Last, humans could be responsible for up to 46.8% and 16.2% of the vanadium accumulation in JZB and LZB, respectively, yet risks to species remain limited.