The Qinghai-Tibet Plateau (QTP) hosts fragile alpine ecosystems sensitive to heavy metals (HMs) contamination, yet systematic research on multi-media transport of HMs from waste residues remains limited. In this study, three typical sampling zones including Forest Shrub Area (FSA), Grass Irrigation Area (GIA) and Shrub Meadow Area (SMA) were chosen. Waste residues, soil, surface water and groundwater samples were gathered, and three-step sequential leaching tests analyzed the speciation characteristics of Cr, Cd, Pb, Hg and As. The geo-accumulation index (Igeo), bioavailability index (BI) and potential ecological risk index (RI) were adopted to characterize HM pollution levels. Multivariate statistical analysis was applied to explore the sources and inter-media migration characteristics of HMs, and the HYDRUS-1D model was utilized to simulate the vertical migration behaviors of metal ions under conventional and seasonal freeze-thaw scenarios. The results demonstrated that HM concentrations in all samples exceeded the local soil background values. Cr, Pb, Hg and As mainly occurred in the residual fraction, whereas Cd exhibited strong bioavailability. Ecological risk assessment suggested that 38% of sampling sites suffered heavy or above ecological risks, with Cd and Hg being the predominant risk contributors. Simulation results proved that Cd migration and groundwater infiltration were regulated by residue pile height and significantly accelerated by seasonal freeze-thaw cycles, posing long-term cumulative ecological risks to plateau groundwater. This study clarifies the correlation between HM potential risks and multi-media transportation, and further interprets differentiated migration and mobilization mechanisms of HMs under anthropogenic disturbances on the QTP.

Soil is a major sink for microplastics (MPs) which can interact with organic contaminants affecting their transport behavior. The impact of MPs in soil matrix is complicated depending on soil-MPs, soil-contaminants and MPs-contaminants interactions, however the study on their interactions is limited. In this study, polyethylene (PE) was selected to investigate its effects on 2,4,6-tribromophenol (TBP) adsorption in soils. TBP adsorption on soils with/without MPs followed pseudo-second order kinetics, and the adsorption isotherm data fitted well with Langmuir and Freundlich models. Compared to pure soil, the presence of PE and aged PE (APE) in soil (1 %, w/w) reduced the adsorption capacity of TBP by 29.4 % and 32.4 %. Meanwhile, the TBP desorption efficiency from soil with PE and APE exceeded that observed in pure soil 31.5 %, which were 36.3 % and 35.7 %, respectively. Consequently, the mobility of TBP in soil could be enhanced increasing its risk to groundwater. With the increment of environmental pH, MPs dosage and ionic strength, the TBP adsorption amount decreased. MPs could compete with TBP for adsorption on soil particles exhibiting an inhibitory effect, since the adsorption energies of MPs-soil and TBP-soil from DFT calculation are strong and on the same level, while the interactions between TBP and MPs are mainly due to van der Waals force. Moreover, the inhibitory effect of APE was weaker than PE, because APE carried more negative charge, resulting from the oxygen-containing functional groups generated during aging, which reduced its affinity towards soil, consequently more vacant sites on soil were left for TBP adsorption.

Globalization has fueled the rapid expansion of international tourism, significantly impacting global food systems. This study aims to quantitatively evaluate the influence of tourism on global food greenhouse gas (GHG) emissions. By integrating the Food and Agriculture Organization Statistical Database and the World Tourism Organization Tourism Statistics database, we analyze regional differences in dietary choices among cross-border tourists and connect them to detailed national-level food supply inventories, enabling us to estimate the GHG emissions associated with cross-border tourism. Additionally, we employ the modified Regional Integrated model of Climate and the Economy (RICE) model to project future trends in tourism-related GHG emissions across regions and countries. Our findings indicate that tourism has resulted in a reduction of 620 Mt CO2e in global food system emissions between 2001 and 2019. Taking into account tourism development trajectories and regional economic growth, our projection suggests that GHG emissions reduction from the global food system resulting from tourism could reach a substantial 96 Mt CO2e per year by 2100. The analysis shows that strengthening the national economy and increasing the labor force, and taking reasonable measures to change the social diet pattern in different regions can further reduce tourism embodied food GHG emissions. This study highlights the significant role of tourism in mitigating global food system emissions and underscores the potential for further emission reductions in the future.

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Porous sludge biochar (PSDBC) and zero-valent iron (ZVI) supported on porous sludge biochar composite (ZVI@PSDBC) were synthesized using municipal sludge through pyrolysis under N2 atmosphere, which manifested upgraded performance in persulfate (PS) activation for 2,4-dichlorophenol (2,4-DCP) degradation. The 2,4-DCP (50 mg/L) could be almost completely removed within 20 min under relatively low PS dosage (0.5 mmol/L) in both PSDBC/PS and ZVI@PSDBC/PS systems, and the mineralization rate could respectively approach 73.7

Zero-valent iron (ZVI) and modified ZVI have been investigated extensively for groundwater remediation. However, ZVI based powder was difficult to be applied directly as permeable reactive barrier (PRB) materials due to their low water permeability and usage rate. In this study, sulfide iron-copper bimetal was prepared by ball milling, which is environment-friendly without second contamination. The optimal preparation parameters of sulfide iron-copper bimetal for Cr(VI) removal were determined (Cu/Fe ratio (w/w), 0.018; FeS/Fe ratio (w/w), 0.1213; ball milling speed, 450 rpm; ball milling time, 5 h). A composite permeable material was prepared by sintering a mixture of sulfide iron-copper bimetal, sludge, and kaolin. The parameters for composite permeable material preparation including sludge content and particle size, and sintering time were optimized, which were 60%, 60–75 mesh, and 4 h, respectively. The optimal composite permeable material was characterized by SEM-EDS, XRD, and FTIR. The results demonstrated preparation parameters can affect the hydraulic conductivity and hardness of composite permeable material. High sludge content, small particles size, and moderate sintering time resulted in high permeability of composite permeable material and were beneficial for Cr(VI) removal. The dominant Cr(VI) removal mechanism was reduction, and the reaction followed pseudo-first order kinetics. Conversely, low sludge content and large particle size, and long sintering time lead to low permeability of composite permeable material. Chromate removal was mainly by chemisorption following pseudo-second order kinetics. The hydraulic conductivity and hardness of the optimal composite permeable material achieved 1.732 cm/s and 50, respectively. The results of column experiments indicated that its Cr(VI) removal capacity was 0.54 mg/g, 0.39 mg/g and 0.29 mg/g at pH 5, 7 and 9, respectively. The ratio of Cr(VI) to Cr(III) on composite permeable material surface was similar under acidic and alkaline conditions. This study will provide an effective reactive material of PRB for field application.

In this study, Cr(VI)-contaminated soil mixed with COPR by using ferrous sulfate (FeSO4), enzyme residue (ER), and their combination under aerobic or anaerobic condition were investigated. The concentration of Cr(VI) decreased from 1498.05 to 104.63 mg kg-1 after the simultaneous addition of FeSO4 (30 %, w/w as FeSO4 & BULL;7H2O) and ER (30 %, w/w) at 45 d under the anaerobic condition with a reduction efficiency of 93.02 %, which is higher than that by single FeSO4 (72.39 %) or ER (75.47 %) under the anaerobic condition. XRD, XPS, FTIR, and fluorescence spec-troscopy were conducted to characterize soil and ER composition. Metagenomic analysis was performed to reveal the reduction mechanisms of FeSO4 and ER. The anaerobic condition with lower Eh was beneficial for Cr(VI) reduction than aerobic condition, and Eh was the main driver for the evolution of Cr(VI) reduction-related microorganisms. Moreover, the addition of ER enriched the organic matter and microbials in the soil. During the decomposition of organic matter under the anaerobic condition, organic acids were generated, leading to a decrease in pH and promot-ing the release of Cr(VI) from minerals. They also served as electron donors in Cr(VI) reduction. Additionally, the addition of excess FeSO4 stimulated the growth of iron-reducing bacteria and sulfate-reducing bacteria, facilitating to Cr(VI) reduction. Metagenomic analysis showed that Acinetobacter, related to the nemA and nfsA genes, was the dominant Cr(VI) reduction genus. Thus, the combination of FeSO4 and ER is a promising method for the remediation of Cr(VI)-contaminated soils mixed with COPR.

Pesticide pollution is an arduous challenge encountered in the field of industrial wastewater treatment. As a Fenton-like metal catalyst, multifunctional biochar has attracted more and more attention in the dissolution of insoluble organic chemical pollutants. In this study, the magnetic municipal sludge biochars(MSDBC)were synthesized by one-step pyrolysis of sludge from sewage treatment plant. The biochars prepared at different temperatures have great differences in surface functional groups and composition of iron phase. MSDBC prepared at 400 degrees C has a better catalytic oxidation capacity, while MSDBC prepared at 800 degrees C has a stronger adsorption capacity. The reason is that the morphology and iron phase composition distribution of biochar are different. More pore structures were formed on the surface of biochar prepared at 800. C, which not only has better adsorption performance, but also makes the impregnated Fe3+ enter the interior of biochar and transform during pyrolysis. However, the iron phase of MSDBC prepared at 400 degrees C is mostly located on the surface and the content of Fe2+ is higher. Notably, iron compounds embedded in the magnetic biochar have been proved to be the main catalysts for activating hydrogen peroxide (H2O2) to produce hydroxyl radicals (center dot OH). Radical quenching experiment and electron paramagnetic resonance (EPR) detection confirmed the production of center dot OH and its important role in the oxidative degradation of thiamethoxam (THX). In the THX degradation, MSDBC/H2O2 Fenton-like system showed excellent effect at neutral pH environment. Finally, the innovative use of MSDBC/ H2O2 Fenton-like technology in the degradation of complex actual wastewater showed good practicability and stability. This research provides a new idea for the treatment of pesticide wastewater.

Development of new binding gels for rapid and simultaneous quantification of bioavailability concentrations of various heavy metals in soils by diffusive gradients in thin film technique. Four binding gels including zinc-aluminum hydrogel (ZnAl-LDH), ethylenediaminetetraacetic acid intercalated zinc-aluminum hydrogel (ZnAl-EDTA-LDHs), polyglutamic acid (PGA), and polyglutamic acid–sodium alginate resin (SA-PGA) were prepared and used for the simultaneous measurement of Cr, Ni, Cu, Cd, and Pb. The adsorption process reached equilibrium in 2 h, which could be considered a pseudo-second-order reaction. Three mol L−1 nitric acid was the best eluent with elution efficiency over 91% for the five heavy metals. Then, SA-PGA gel was assembled into DGT device (SA-PGA-DGT). Its performance was virtually unaffected by pH (5–9), ionic strength (1–50 mM), and soil properties with adsorption capacities 5.02 μg cm−2, 11.38 μg cm−2, 8.16 μg cm−2, 17.11 μg cm−2, and 89.43 μg cm−2 for Cr, Ni, Cu, Cd, and Pb, respectively. A good linear correlation was observed between the concentrations of Cr, Ni, Cu, Cd, and Pb determined by SA-PGA-DGT in soil samples from Tanggu District in China and the exchangeable contents of the five metals determined by the Tessier method, with R values of 0.64, 0.63, 0.59, 0.72, and 0.64 (p < 0.01). SA-PGA gel exhibited the best adsorption properties among the four gels. SA-PGA-DGT can be used as a reliable tool for rapid and simultaneous quantification of bioavailability concentrations of multiple heavy metals.

The alkali digestion pretreatment method in the United States Environmental Protection Agency (USEPA) Method 3060A could underestimate the content of Cr(VI) in Cr-contaminated soils, especially for soils mixed with chromite ore processing residue (COPR), which leads to a misjudgment of the Cr(VI) level in soils after remediation, causing secondary pollution to the environment. In this study, a new pretreatment method to analyze Cr(VI) concentration in contaminated soils was established. The impacts of soil quality, particle size, alkali digestion time and the rounds of alkali digestion on Cr(VI) detection in contaminated soils was explored and the alkali digestion method was optimized. Compared with USEPA Method 3060A, the alkaline digestion time was prolonged to 6 h and multiple alkali digestion was employed until the amount of Cr(VI) in the last extraction was less than 10% of the total amount of Cr(VI). Because Cr(VI) in COPR is usually embedded in the mineral phase structure, the hydration products were dissolved and Cr(VI) was released gradually during the alkaline digestion process. The amount of Cr(VI) detected showed high correlation coefficients with the percentage of F1 (mild acid-soluble fraction), F2 (reducible fraction) and F4 (residual fraction). The Cr(VI) contents detected by the new alkaline digestion method and USEPA Method 3060A showed significant differences for soil samples mixed with COPR due to their high percentage of residual fraction. This new pretreatment method could quantify more than 90% of Cr(VI) in Cr-contaminated soils, especially those mixed with COPR, which proved to be a promising method for Cr(VI) analysis in soils, before and after remediation.

It is possible for heavy metals in soils to be adsorbed by crop roots and then accumulated in crops, which eventually causes great health risk when the crops are ingested by humans. Thus, it is valuable to understand the enrichment model of heavy metals in crops. Diffusive gradients in thin-films (DGT) technique, as an in-situ passive sampling method, can be used to evaluate the bioavailable heavy metals contents in soils. In this study, data of the bioavailable cadmium (Cd) in soils determined by DGT and Cd contents uptake in rice and maize grains in Tianjin, Zhejiang and Guangxi provinces of China were collected from previous references in Web of Science. By comparing bioconcentration factors, it was found that the heavy metal concentrations accumulated in rice and maize followed a general order roots > stems or leaves > grains. An accurate and robust model for the prediction of Cd content in maize and rice grains was established based on bioconcentration factor (BCF) and the bioavailable Cd content determined by DGT method, with R2 0.986 and root mean square error (RMSE) 0.128. This result suggests that the DGT method can be good tool for predicting heavy metals uptake in crops.

The evaluation of the soil contaminated by heavy metals can help to judge whether the soil meets the standard and whether the pollution will threaten human health and the ecological environment. In this study, the farmland soil from eight districts in Beijing was used as the research object, and the concentration of heavy metal elements, Pb, As and Cd in the soils and agricultural products were analyzed. The analysis results showed that: (1) The evaluation based on the improved Hakanson method suggested that the crops exhibit a significantly higher ability to absorb Cd than to absorb Pb and As. Pb, As and Cd are all at normal level of ecological risk; among them, Cd is mainly in a moderate ecological risk, without strong ecological risk. (2) Based on the Improved analytic hierarchy process(AHP) of evaluation, 0.2317 is the average value of the integrated index of heavy metal pollution of soil in the study area, which is a mild level of pollution. (3) Through the calculation of various parameters in the Influence index of comprehensive quality(IICQ) of soil and agricultural products, it was found that 0＜IICQS＜1, suggesting that the environmental quality of soil is at a clean level. In summary, the pollution of heavy metals Pb, As and Cd in the farmland soils and crops in the eight districts of Beijing, including Fangshan, Daxing, Shunyi, and Shijingshan is at a low level, and no significant impact has been brought to the surrounding environment.

Sodium alginate-polyglutamic acid was used to develop a new diffusive gradient in thin films (SA-PGA-DGT) device, which was proven to be suitable for the investigation of labile Cd in soil. The adsorption capacity of Cd was calculated to be approximately 16.8 μg/cm2 , which was hardly affected by factors including pH (5-9), ionic strength (0.1-100 mM), and the presence of other metals (Pb, Cu, Ni, and Cr). The SA-PGA gel has dense and uneven pores with large specific surface area, which ensures the adsorption of Cd by functional groups of the gel. A kinetics study indicated that the adsorption rate of Cd by the binding gel can be described as a pseudo-second-order reaction. Deployment of the SA-PGA-DGT in the soils of Tang Gu (located in Binhai New District, Tianjin, China) showed a strong positive linear correlation between Cd measured by the device and exchangeable Cd measured by the Tessier method (R = 0.73, p < 0.01). Cadmium determined by the SA-PGA-DGT device was less affected by soil properties. This new SA-PGA-DGT has obvious advantages over other methods in respect of the labile Cd analysis in soil. The innovative novel device expands the variety of existing DGT technologies and can be utilized to monitor the level of labile Cd in soil effectively. Environ Toxicol Chem 2021;40:1559-1569. © 2021 SETAC.

The pollution of perfluorooctanoic acid (PFOA) in water bodies has been a serious threat to environment and human health. Ordered mesoporous carbons (OMCs) with different oxygen contents were prepared and first used for adsorbing PFOA from aqueous solutions. The OMC-900 with a lower oxygen content has a higher PFOA adsorption capacity than the oxygen-rich OMC-700. OMCs require a much shorter time to reach the adsorption equilibrium comparing with other adsorbents reported in literature. The mesopores play an important role in this rapid adsorption kinetics. The pseudo-second-order model better fitted the kinetic data. The multilayers adsorption was proposed for the adsorption of PFOA onto OMCs since the Freundlich isotherm model fits the experimental data well. The micelle or hemi-micelle structures may be formed during the adsorption. Various background salts showed a positive effect on PFOA adsorption due to the salting-out and divalent bridge effects. The humic acid can lead to a discernible reduction in PFOA adsorption by competing for adsorption sites on OMCs. The hydrophobic interaction and electrostatic interaction adsorption mechanisms were proposed and verified by the adsorption data. The high adsorption capacity and fast adsorption kinetics of the OMC make it a potential adsorbent for PFOA removal in engineering applications.

Tianjin, as an important maize production region in China, has a long history of sewage irrigation resulting in the soil cadmium (Cd) contamination. In this study, single extractions of CaCl2 and HNO3, BCR sequential extraction and the diffusive gradients in thin films technique (DGT) were used to measure the bioavailable Cd content in soils. The Cd content in soil samples all exceeded the background values, with 14.3% and 33.3% of sites in the Baodi District (BDD) and Jinghai District (JHD) exceeding the risk control values, respectively. The average content of Cd in maize samples is lower than the pollution control values, which may be related to the higher pH (8.53) and organic matter (OM) content (15.01 g kg-1) in soils. Bioavailable Cd measured by DGT correlated well with Cd in maize grains (R2 =0.92). The DGT and DIFS model predicted the metals release from the agricultural lands, the total concentration of Cd in soil was relatively low, but the labile Cd in the soils has adequate metal release capability. This study shows that DGT is efficient in predicting Cd accumulation in grains from contaminated soils.

This paper analyzes the characteristics of waste electrical and electronic equipment (WEEE) market in China and the findings are as follows: WEEE are still seen as valuable goods, and a recovery and recycling system is thus in place naturally in China like in many other developing countries. A game theory model is therefore built here to find out how effective funding is for this recovery and recycling system. Analysis of this model reveals: (1) Some dismantling enterprises (formal dismantling enterprises) are in this funding system, while others (informal ones) are not, thus forming a dual WEEE dismantling system, after the funding system was launched; (2) To ensure effectiveness of the funding system, the funding provided for formal enterprises for each piece of WEEE they handle, after deducting the incremental cost incurred for environmental compliance, must exceed the difference between the unit selling prices of the dismantled devices at formal and informal dismantling enterprises. This difference is RMB 70.2, RMB 67.9, RMB 22.2, RMB 79.4 and RMB 68.3 respectively for televisions, refrigerators, washing machines, air conditioners and computers; (3) When the funding system was launched, WEEE recovery enterprises would raise WEEE prices to seek profit and this would channel part of the funding into the recovery segment of the market.

Mesoporous graphitic carbon nitride (MCN) photocatalyst was blended in polyvinylidene fluoride (PVDF) membrane through immersion-precipitation phase transformation. Various techniques were adopted to characterize the structure and morphology of MCN-PVDF hybrid membrane, which indicated that MCN was successfully integrated in PVDF. The MCN80-PVDF membrane exhibited enhanced hydrophilicity and antifouling properties. As the amount of MCN addition increased, the contact angle of membranes decreased from 68.33° to 57.12°, whereas the flux recovery rate increased by 28% as compared to the pristine PVDF. Meanwhile, MCN-PVDF membrane possessed photocatalytic, self-cleaning and antimicrobial activities. The MCN80-PVDF membrane was used to degrade cefotaxime (CFX) under sunlight irradiation. After five cycles of experiments, the degradation rate of CFX remained 97.4%. Additionally, MCN80-PVDF membrane achieved 3 log of E. coli inactivation under visible light irradiation for 4 h. The photogenerated h+ and reactive oxidative species were the primary reason for organics’ degradation and bacterial inactivation. In summary, the prepared hybrid MCN80-PVDF membrane with sunlight irradiation exhibited great potential for the treatment of real wastewater.

Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) were investigated from effluent of two hospital and two municipal wastewater treatment plants (WWTPs) before and after disinfection. The results of network analysis showed that 8 genera were identified to be the main potential hosts of ARGs, including Mycobacterium, Ferruginibacter, Thermomonas, Morganella, Enterococcus, Bacteroides, Myroides and Romboutsia. The removal of ARGs and their possible bacterialhosts were synchronous and consistent by chlorine or ultraviolet (UV) disinfection in WWTPs. The mechanisms of ARB and ARGs removal, and conjugation transfer of RP4 plasmids by UV, chlorine and synergistic UV/chlorine disinfection was revealed. Compared to UV alone, ARB inactivation was improved 1.4 log and photoreactivation was overcome-effectively by UV/chlorine combination (8 mJ/cm(2), chlorine 2 mg/L). However, ARGs degradation was more difficult than ARB inactivation. Until UV dosage enhanced to 320 mJ/cm(2), ARGs achieved 0.58-1.60 log removal. Meanwhile, when 2 mg/L of chlorine was combined with UV combination, ARGs removal enhanced 1-1.5 log. The synergistic effect of adding low-dose chlorine (1-2 mg/L) during UV radiation effectively improved ARB and ARGs removal simultaneously. The same synergistic effect also occurred in the horizontal gene transfer (HGT). Non-lethal dose chlorine (0.5 mg/L) increased the conjugation transfer frequency,which confirmed that the mRNA expression levels of type IV secretion system (T4SS) proteins vir4D, vir5B and vir10B were significantly enhanced. The risk of RP4 plasmid conjugation transfer was significantly reduced with UV/chlorine (UV >= 4 mJ/cm(2), chlorine >= 1 mg/L). These findings may serve as valuable implications for assessing and controlling the risk of ARGs transfer and propagation in the environment. (c) 2020 Elsevier Ltd. All rights reserved.

Artificial recharge to groundwater with reclaimed water is considered a promising method to alleviate groundwater depletion and over-exploitation. However, the occurrence of fluoroquinolone antibiotics (FQs) was ubiquitous in wastewater, surface water, groundwater and even drinking water threating human health and ecology. In this study, the occurrence of six selected FQs in reclaimed water effluent and their removal by tertiary treatment units were investigated. The overall removal efficiencies in average of the tertiary treatment processes in Beijing and Changzhou were ranging from 21.2% to 55.2%. Activated carbon exhibited better performance for FQs removal than ozone and biological treatment such as membrane bioreactor, anaerobic-anoxic-oxic and biofilter. The results of two pilot study showed that the impact of reclaimed water to groundwater quality in terms of FQs concentration by direct injection in GBD was stronger than surface spreading in Changzhou, which might be due to the recharge strategy and the physical and chemical characteristics of sediment and aquifer soil. The hazard quotient (HQ) values of ofloxacin (OFL) in reclaimed water was up to 12.54, indicating the extreme eco-toxicological risk, while enrofloxacin (ENR) exhibited medium risk. After recharge with reclaimed water, the HQ values of OFL and ENR in groundwater ranged from low to medium ecological risk to the environment. Thus, the FQs in reclaimed water need to be paid more attention during their reuse for groundwater recharge, especially by direct injection. It is suggested that FQs should be considered in the priority substances lists in standards and guidelines of reclaimed water reuse for groundwater recharge to ensure the safety of groundwater.

Recently, industrial parks have played a vital role for economic development in many countries. Enterprises in industrial park benefit from shared infrastructure, services, energy and resources et al., however the use or storage of large quantities of dangerous substances possess threat to human health and surrounding environment. Hence, the management and control of environmental risk are crucial to industrial parks, especially chemical industrial parks. Up to now, there aren't any specific standard methods or guidelines for industrial park environmental risk assessment (ERA). Various qualitative and quantitative methods have been developed and adopted by researchers in literature. The purpose of this study is to summarize current approaches for industrial park ERA. As the identification of environmental risk source is the first and crucial step affecting the results of ERA significantly, firstly we introduced the approaches for risk sources identification. Then, we classified the risk characterization approaches based on their theories including analytic hierarchy process based method, catastrophe progression method, fuzzy mathematics based methods, environmental risk field based method, etc., and summarized their principles and applications. Through the comparison of the advantages and limitations of these approaches, the future research trend for industrial park ERA is forecasted to help to manage and control environmental risk effectively.