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Rethinking hydrocarbons build-up on urban roads: A perspective on volatilisation under global warming scenarios
2019
Wijesiri, Buddhi | Liu, An | Hong, Nian | Zhu, Panfeng | Yang, Bo | Zhao, Xu | Goonetilleke, Ashantha
Stormwater is viewed as an alternative resource to mitigate water shortages. However, stormwater reuse is constrained due to the presence of many toxic pollutants such as hydrocarbons. Effective mitigation requires robust mathematical models for stormwater quality prediction based on an understanding of pollutant processes. However, the rise in global temperatures will impose changes to pollutant processes. This study has proposed a new perspective on modelling the build-up process of hydrocarbons, with a focus on volatile organic compounds (VOCs). Among organic compounds, VOCs are the most susceptible to changes as a result of global warming due to their volatility. Seven VOCs, namely, benzene, toluene, ethylbenzene, para-xylene, meta-xylene, ortho-xylene and styrene in road dust were investigated. The outcomes are expected to lay the foundation to overcoming the limitations in current modelling approaches such as not considering the influence of temperature and volatility, on the build-up process. A new conceptualisation is proposed for the classical build-up model by mathematically defining the volatility of VOCs in terms of temperature. Uncertainty in the re-conceptualised build-up model was quantified and was used to understand the build-up patterns in the future scenarios of global warming. Results indicated that for the likely scenarios, the variability in VOCs build-up gradually increases at the beginning of the dry period and then rapidly increases after around seven days, while the build-up reaches a near-constant value in a shorter dry period, limiting the variability. These initial research outcomes need to be further investigated given the expected impacts of global warming into the future.
Afficher plus [+] Moins [-]Simultaneous Cr(VI) reduction and electricity generation in Plant-Sediment Microbial Fuel Cells (P-SMFCs): Synthesis of non-bonding Co3O4 nanowires onto cathodes
2019
Cheng, Ce | Hu, Yongyou | Shao, Sicheng | Yu, Jiayuan | Zhou, Weijia | Cheng, Jianhua | Chen, Yuancai | Chen, Shengnan | Chen, Junfeng | Zhang, Lihua
Development of low-cost cathode materials for Plant-Sediment Microbial Fuel Cells (P-SMFCs) has gained increasing interest, due to improved performance levels in terms of power and pollutant removal. A novel low cost three-dimensional cathode prepared by simple three-step strategy with growth of Co₃O₄ in-situ biofilm was successfully prepared. Different cathodes were applied to the six parallel P-SMFCs systems (reactor: R1-R6), such as graphite felt (GF), Pt/C, GF@Co₃O₄ (non-bonding Co₃O₄ nanowires on GF), GF@SG-Co₃O₄ (using argon as shielding gas (SG)). Its performances (R1, R2: control groups) were evaluated by electricity generation and Cr(VI) reduction at initial cadmium concentrations (4.97, 10.29 and 21.16 mg L⁻¹). A significant Cr(VI) removal efficiency of 99.76%, maximum power density of 75.12 ± 2.90 mW m⁻² and Cr(VI) adsorption capacity of 1.67 mg g⁻¹ were obtained at initial Cr(VI) concentration of 21.16 mg L⁻¹ with non-bonding GF@Co₃O₄ and bio-GF@SG-Co₃O₄ as cathodes. This indicated that these two materials were better than others (GF, Pt/C and GF@Co₃O₄) as cathodes. Characterization analysis including scanning electron microscope (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), Polarization curve, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) showed that high current generation Cr(VI) removal mainly attributed to transportation of plants, adsorption of bio-cathode, formation of a relatively high concentration region and abundant oxygen vacancies of GF@SG-Co₃O₄. The results show that P-SMFCs with GF@SG-Co₃O₄ cathode may be a potentially novel approach for remediating Cr(VI) contaminated waster or soil.
Afficher plus [+] Moins [-]Sustainable alternatives to 1,3-dichloropropene for controlling root-knot nematodes and fungal pathogens in melon crops in Mediterranean soils: Efficacy and effects on soil quality
2019
Montiel-Rozas, María del Mar | Hurtado-Navarro, María | Díez-Rojo, Miguel Ángel | Pascual, José A. (José Antonio) | Ros, Margarita
The control of agricultural pests is key to maintain economically viable crops. Increasing environmental awareness, however, is leading to more restrictive European policies regulating the use of certain pesticides due to their impact on human health and the soil system. Given this context, we evaluated the efficacy of three alternatives to the soil fumigant 1,3-dichloropropene (1,3-D), which is currently banned in Europe: two non-fumigant nematicides [oxamyl (OX) and fenamiphos (FEN)] and the soil fumigant dimethyl disulfide (DMDS). We analysed the efficiency of these pesticides against root-knot nematodes and soil fungal pathogens (determined by qPCR) as well as the soil biological quality after treatments application (estimated by enzyme activities). Among treatments, 1,3-D and DMDS significantly reduced nematode populations. FEN was more effective in sandy soil, while OX had no effect in any soil. OX and FEN had no effect on fungal pathogens, whereas DMDS reduced the abundance of Rhizoctonia solani and Fusarium solani at the root level in clay-loam soil. Soil quality decreased after treatment application but then recovered throughout the experiment, indicating the possible dissipation of the pesticides. Our findings support DMDS as a potential sustainable alternative for controlling root-knot nematodes and fungal pathogens due to its effectiveness in both studied soils, although its negative impact on soil biological quality in sandier soils must be taken into account.Main finding of the work. DMDS is a reliable alternative to 1,3-D for controlling agricultural pest but its inhibitory effect on soil enzyme activities varied according to the soil characteristics.
Afficher plus [+] Moins [-]Enhanced degradation of triphenyl phosphate (TPHP) in bioelectrochemical systems: Kinetics, pathway and degradation mechanisms
2019
Hou, Rui | Luo, Xiaoshan | Liu, Chuangchuang | Zhou, Lihua | Wen, Junlin | Yuan, Yong
Triphenyl phosphate (TPHP) is one of the major organophosphate esters (OPEs) with increasing consumption. Considering its largely distribution and high toxicity in aquatic environment, it is important to explore an efficient treatment for TPHP. This study aimed to investigate the accelerated degradation of TPHP in a three-electrode single chamber bioelectrochemical system (BES). Significant increase of degradation efficiency of TPHP in the BES was observed compared with open circuit and abiotic controls. The one-order degradation rates of TPHP (1.5 mg L⁻¹) were increased with elevating sodium acetate concentrations and showed the highest value (0.054 ± 0.010 h⁻¹) in 1.0 g L⁻¹ of sodium acetate. This result indicated bacterial metabolism of TPHP was enhanced by the application of micro-electrical field and addition acetate as co-substrates. TPHP could be degraded into diphenyl phosphate (DPHP), hydroxyl triphenyl phosphate (OH-TPHP) and three byproducts. DPHP was the most accumulated degradation product in BES, which accounted more than 35.5% of the initial TPHP. The composition of bacterial community in BES electrode was affected by the acclimation by TPHP, with the most dominant bacteria of Azospirillum, Petrimonas, Pseudomonas and Geobacter at the genera level. Moreover, it was found that the acute toxic effect of TPHP to Vibrio fischeri was largely removed after the treatment, which revealed that BES is a promising technology to remove TPHP threaten in aquatic environment.
Afficher plus [+] Moins [-]Municipal solid waste (MSW) incineration fly ash as an important source of heavy metal pollution in China
2019
Wang, Ping | Hu, Yuanan | Cheng, Hefa
Incineration has overtaken landfilling as the most important option for disposal of the increasing volumes of municipal solid waste (MSW) generated in China. Accordingly, disposal of the incineration fly ash, which is enriched with a range of heavy metals, has become a key challenge for the industry. This review analyzes the temporal and spatial trends in the distributions of As, Cd, Cr, Cu, Ni, Pb, Zn, and Hg in MSW incineration fly ash between 2003 and 2017, and estimates the inventories of heavy metals associated with the fly ash and the average levels of heavy metals in Chinese MSW based on their mass flow during MSW incineration. It was estimated that MSW incinerators in China released approximately 1.12 × 10², 2.96 × 10³, 1.82 × 10², 3.64 × 10⁴, 1.00 × 10², 7.32 × 10³, 2.42 × 10², and 1.47 × 10¹ tonnes of Cd, Pb, Cr, Zn, Ni, Cu, As, and Hg, respectively, with the fly ash in 2016. Due to the much greater fly ash generation rate, the incinerators based on circulating fluidized bed combustor (CFBC) technology released more heavy metals during incineration of MSW compared to those based on grate furnace combustor (GFC) technology. Results of mass-flow modeling indicate that the geometric mean contents of Cd, Pb, Cr, Zn, Ni, Cu, As, and Hg in Chinese MSW were 3.0, 109, 101, 877, 34, 241, 21, and 1.7 mg/kg, respectively, which are comparable to those in the MSW from other countries. To protect the environment from the significant potential ecological risk posed by heavy metals in the mismanaged fly ash, strict regulation enforcement and compliance monitoring are necessary to reduce the heavy metal pollution brought by improper disposal of MSW incineration fly ash, and more research and development efforts on advanced technologies for stabilization of heavy metals in fly ash and its environmentally sound reuse can help mitigate its environmental risk.
Afficher plus [+] Moins [-]Urinary parabens in children from South China: Implications for human exposure and health risks
2019
Lu, Shaoyou | Ren, Lu | Liu, Yanlin | Ma, Huimin | Liu, Shan | Zhu, Zhou | Tang, Zhi | Kang, Li | Liao, Shicheng
Parabens are extensively applied in cosmetics, drugs or food as preservatives and have become common pollutants in environmental media. However, data on human exposure to these chemicals is still limited, especially for children. This study aimed to investigate parabens in urine samples of children and to evaluate the cumulative risk of paraben exposure. Five short-chain parabens were measured in 255 urine samples collected from children in a kindergarten and elementary schools from South China. Methyl paraben (MeP), ethyl paraben (EtP) and n-propyl paraben (PrP) were widely detected in urine samples (detection rates > 94.9%), indicating their widespread exposure. The urinary median concentrations of MeP, EtP and PrP were 2.25, 0.33 and 0.50 μg/L, respectively. Significantly positive correlations (p < 0.01) were observed between MeP and PrP in urine, suggesting similar sources and/or metabolic pathways of these two chemicals. The median estimated daily intakes (EDIs) of parabens were determined to be 18.1 and 9.79 μg/kg-bw/day for kindergarten children and elementary school students, respectively. Estimation of human intake and exposure risks indicated potential risks of PrP exposure for elementary school students. This is the first study addressing paraben exposure in South China children.
Afficher plus [+] Moins [-]Partitioning of chemical contaminants to microplastics: Sorption mechanisms, environmental distribution and effects on toxicity and bioaccumulation
2019
Tourinho, Paula S. | Kočí, Vladimír | Loureiro, Susana | van Gestel, Cornelis A.M.
There is an increasing awareness of the threats posed by the worldwide presence of microplastics (MPs) in the environment. Due to their high persistence, MPs will accumulate in the environment and their quantities tend to increase with time. MPs end up in environments where often also chemical contaminants are present. Since the early 2000s, the number of studies on the sorption of chemicals to plastic particles has exponentially increased. The objective of this study was to critically review the literature to identify the most important factors affecting the sorption of chemical contaminants to MPs. These factors include the physicochemical properties of both the MPs and the chemical contaminants as well as environmental characteristics. A limited number of studies on soil together with an increased notion of the importance of this compartment as a final sink for MPs was observed. Therefore, we assessed the distribution of model chemicals (two PCBs and phenanthrene) in the soil compartment in the presence of MPs using a mass balance model. The results showed a high variation among chemicals and microplastic types. Overall, a higher partitioning to MPs of chemical contaminants in soil is expected in comparison to aquatic environments. As sorption to a large extent determines bioavailability, the effects of combined exposure to chemicals and MPs on the toxicity and bioaccumulation in biota are discussed. Finally, some considerations regarding sorption and toxicity studies using MPs are given.
Afficher plus [+] Moins [-]Effects of tetracycline residuals on humification, microbial profile and antibiotic resistance genes during vermicomposting of dewatered sludge
2019
Xia, Hui | Chen, Jingyang | Chen, Xuemin | Huang, Kui | Wu, Ying
Vermicomposting is a green technology used in the recycling of sewage sludge using the joint action of earthworms and microorganisms. Although tetracycline is present in abundance in sewage sludge, little attention has been given to its influence on vermicomposts. This study investigated the effects of different tetracycline concentrations (0, 100, 500 and 1000 mg/kg) on the decomposition of organic matter, microbial community and antibiotic resistance genes (ARGs) during vermicomposting of spiked sludge. The results showed that 100 mg/kg tetracycline could stimulate earthworms’ growth, accompanied by the highest humification and decomposition rates of organic matter in the sludge. The abundance of active microbial cells and diversity decreased with the increase in tetracycline concentrations. The member of Bacteroidetes dominated in the tetracycline spiked treatments, especially in the higher concentration treatments. Compared to its counterparts, the addition of tetracycline significantly increased the abundances of ARGs (tetC, tetM, tetX, tetG and tetW) and Class 1 integron (int-1) by 4.7–186.9 folds and 4.25 folds, respectively. The genera of Bacillus and Mycobacterium were the possible bacterial pathogen hosts of ARGs enriched in tetracycline added group. This study suggests that higher concentration of tetracycline residual can modify microbial communities and increase the dissemination risk of ARGs for final sludge vermicompost.
Afficher plus [+] Moins [-]Extreme enrichment of arsenic and rare earth elements in acid mine drainage: Case study of Wiśniówka mining area (south-central Poland)
2019
Migaszewski, Zdzisław M. | Gałuszka, Agnieszka | Dołęgowska, Sabina
The Wiśniówka rock strip mining area (south-central Poland) with quartzite quarries, acid water bodies and tailings piles is one of the most unique acid mine drainage (AMD) sites throughout the world. This is due to the occurrence of enormous amounts of pyrite unknown in sedimentary formations worldwide. Of the two mineralization zones, one that is the most abundant in arsenical pyrite occurs in the lowermost Upper Cambrian formation of the Podwiśniówka quarry. The As-rich pyritiferous clastic rocks are exposed as a result of deep quartzite extraction during 2013–2014. In addition, the clayey-silty shale interbeds are enriched in rare earth element (REE) minerals. The mining operation left an acidic lake with a pH of about 2.4–2.6 and increased contents of sulfates, metal(loid)s and REE. The Podwiśniówka pyrite-rich waste material was stacked up in many places of the mining area giving rise to strongly acidic spills that jeopardized the neighboring environment. One of these unexplored tailings piles was a source of extremely sulfate- and metal(loid)-rich pools with unusual enrichments in As (up to 1548 mg L⁻¹) and REE (up to 24.84 mg L⁻¹). These distinctly exceeded those previously reported in the Wiśniówka area. A broad scope of geochemical, mineralogical and petrographic methods was used to document these specific textural and mineralogical properties of pyrite facilitating its rapid oxidation. The pyrite oxidation products reacted with REE-bearing minerals releasing these elements into acid water bodies. Statistical methods were employed to connect the obtained tailings pool hydrogeochemical data with those derived from this and the previous studies of the Podwiśniówka and Wiśniówka Duża acid pit lakes. In contrast to metal(loid) profiles, the characteristic shale-normalized REE concentration patterns turned out to be more suitable for solving different AMD issues including provenance of mine waste material in the tailings pile examined.
Afficher plus [+] Moins [-]Species and release characteristics of VOCs in furniture coating process
2019
Qi, Yiqing | Shen, Liming | Zhang, Jilei | Yao, Jia | Lu, Rong | Miyakoshi, Tetsuo
Volatile organic compounds (VOCs) are an important factor affecting ambient air quality, and furniture production is one of the important sources of VOC pollution. High VOC concentrations have adverse effects on the environment and worker welfare in furniture factories. In order to control VOC emissions in a furniture workshop, the VOC species and concentration distributions were examined. Qualitative analysis of VOC species was carried out by headspace gas chromatography/mass spectrometry. The results showed that VOCs from a furniture workshop were mainly 12 substances including acetate, toluene, and xylene compounds. The heights and representative positions of VOCs released during the coating process were determined, and the results showed that VOC concentrations depended on environmental and height factors. The concentration of VOCs decreased with increasing altitude and reached a maximum concentration at 0.4 m above the ground. Because the concentration of VOCs varied with temperature, humidity, air pressure, and amount of spray paint, this paper established functional relationships between VOC concentrations and temperature, humidity, air pressure, and amount of spray paint. These results provide a theoretical basis for furniture workshops to automatically monitor and control VOCs.VOCs from the furniture workshop were mainly composed of 10 substances including acetate, toluene, and xylene compounds.
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