21. 题目: Spatiotemporal Variability of the Nitrous Oxide Concentrations and Fluxes From a Cascaded Dammed River
期刊: Frontiers in Environmental Science
作者: Shengnan Wu, Xiaofeng Wang, Tingting Liu, Yixin He, Ziyi Que, Jilong Wang, Hang Li, Lele Yu, Yuanyuan Zhang, Xingzhong Yuan
摘要: Rivers have been largely considered as the source of nitrous oxide (N 2 O) to the atmosphere. N 2 O emissions from rivers could be seriously influenced by damming and exhibit unique spatiotemporal patterns in river-reservoir systems. Multiple research studies report N 2 O emissions from rivers with single reservoirs, but the spatiotemporal patterns and controls of N 2 O emissions from cascaded river-reservoir system remain unclear. In this study, we investigated the spatiotemporal variations of N 2 O concentrations and fluxes along a cascade damming river (Wubu River) in Southwest China. Our results showed that N 2 O concentrations in the Wubu River ranged from 2.5 to 283.2 nmol L −1 with a mean of 50.7 ± 52.3 nmol L −1 and were generally supersaturated with gas fluxes ranging from 11.8 to 805.6 μmol m −2 d −1 . N 2 O concentrations and fluxes showed a significant longitudinal variation with increasing fluxes from upstream to downstream. Meanwhile, for each river-reservoir-released water continuum, local variation of N 2 O concentrations was also prominent. Reservoir sections and released water sections had 2.7 (1.2–7.9) and 3.4 (1.3–12.2) times higher N 2 O concentrations than the corresponding upstream river reaches and acted as hotpots for N 2 O emission. The N 2 O concentrations had significant correlations with organic carbon, phosphorus, and Chl-a in surface water. Furthermore, the N 2 O concentrations and fluxes in reservoirs had a significant correlation with hydraulic residence time and hydraulic load, suggesting that fragmentation of hydrologic conditions was an important driver for the spatial variations of N 2 O concentrations in the Wubu River cascade reservoirs. Our results suggested that hydraulic residence time could predict the variation pattern of N 2 O fluxes in this small river basin. Seasonal variations of N 2 O concentrations and fluxes were the highest in autumn and lowest in winter and were mainly attributed to temperature and rainfall. N 2 O fluxes were much higher in the Wubu River than the average levels of China’s reservoirs and global reservoirs, acting as enhanced N 2 O emitter. Our study highlighted that the cascade reservoirs not only act as exciters for N 2 O production and emissions but also form cumulative effects and local hotpots along the longitudinal dimension, which could significantly increase the complexity of the spatiotemporal variability in riverine N 2 O emissions. Given the increasing construction of new river dams due to growing energy demand, more research should be done to quantify the contribution of cascaded damming to riverine N 2 O budgets.
22. 题目: Phototransformation of tetrabromobisphenol A in saline water under simulated sunlight irradiation
作者: Xue Feng, Jinsheng Wei, Xuefeng Hu, Baiyu Liu, Chen Yang, Junhan Yang
摘要: The widespread use of halogenated flame retardants in recent years has led to the accumulation of TBBPA in water, which may cause potential harm to living organisms. The phototransformation of the flame retardant TBBPA in alkaline saline water under simulated sunlight irradiation was investigated. The effects of abiotic factors such as the initial concentration of TBBPA, chloride ion concentration, solution pH, inorganic anions and cations, dissolved organic matter (DOM) were studied. The results showed that the phototransformation rate of TBBPA accelerated with the decrease of the initial concentration of TBBPA, the increase of chloride ion concentration and solution pH. The scavenging experiments showed that •OH, 1O2, O2•- and 3TBBPA* all participated in the phototransformation of TBBPA. The presence of NO3−, CO32−, SO42−, Mg2+, Ca2+, Fe3+ and fulvic acid (FA) all inhibited the phototransformation of TBBPA in the present study. The phototransformation products of TBBPA were detected by liquid chromatography-mass spectrometry (LC-MS), and the phototransformation pathways were proposed. This is the first report on the photo-induced generation of halogen exchange products from TBBPA in saline solutions, which will contribute to a better understanding of the environmental behavior and risks of BFRs in water.
23. 题目: Hydroxylamine enhanced Fe(II)-activated peracetic acid process for diclofenac degradation: Efficiency, mechanism and effects of various parameters
期刊: Water Research
作者: Jinbin Lin, Jing Zou, Hengyu Cai, Yixin Huang, Jiawen Li, Junyang Xiao, Baoling Yuan, Jun Ma
摘要: In this study, a commonly used reducing agent, hydroxylamine (HA), was introduced into Fe(II)/PAA process to improve its oxidation capacity. The HA/Fe(II)/PAA process possessed high oxidation performance for diclofenac degradation even with trace Fe(II) dosage (i.e., 1 μM) at pH of 3.0 to 6.0. Based on electron paramagnetic resonance technology, methyl phenyl sulfoxide (PMSO)-based probe experiments and alcohol quenching experiments, FeIVO2+ and carbon-centered radicals (R-O•) were considered as the primary reactive species responsible for diclofenac elimination. HA accelerated the redox cycle of Fe(III)/Fe(II) and itself was gradually decomposed to N2, N2O, NO2− and NO3−, and the environmentally friendly gas of N2 was considered as the major decomposition product of HA. Four possible degradation pathways of diclofenac were proposed based on seven detected intermediate products. Both elevated dosages of Fe(II) and PAA promoted diclofenac removal. Cl−, HCO3− and SO42− had negligible impacts on diclofenac degradation, while humic acid exhibited an inhibitory effect. The oxidation capacity of HA/Fe(II)/PAA process in natural water matrices and its application to degrade various micropollutants were also investigated. This study proposed a promising strategy for improving the Fe(II)/PAA process and highlighted its potential application in water treatment.
24. 题目: Low electric field assisted surface conductive membrane in AnMBR: Strengthening effect and fouling behavior
期刊: Chemical Engineering Journal
作者: Lutian Wang, Yun Wu, Yangfan Fu, Lijuan Deng, Yue Wang, Yue Ren, Hongwei Zhang
摘要: This study investigated the possibility of using a novel type of surface conductive hollow fiber membrane during the anaerobic membrane bioreactor process (AnMBR). In particular, the membrane fouling control mechanisms of Surface electric field AnMBR (S-AnEMBR) were evaluated through comparing with the operation of Conventional AnMBR (AnMBR) and Electric field AnMBR (AnEMBR). Results showed that S-AnEMBR had longer running time, stronger anti-fouling capability, and more stable total organic carbon (TOC) removal efficiency. And S-AnEMBR could extend the running time of the rapid fouling phase (Stage 2). Electrochemical analysis and microbial community analysis showed that enhanced electron transfer in S-AnEMBR accelerated the decomposition of organic matter and further improved acidification efficiency from 83.75% to 234.78%, indicating the methane concentration ranged between 24.56 mmol/L and 36.99 mmol/L. Cake layer compression was reduced because significant changes were observed in increased particle size and more negative Zeta potential. In addition, basophilic methanogens (48%) were enriched at cathode, which improved electrochemical activity of carbon electrode biocathode and promoted anaerobic digestion. Therefore, it was found that S-AnEMBR was more conducive to controlling the properties and structure of the gel layer, and further achieving the resistance towards protein and polysaccharide adhesion in membrane. This work demonstrated that the surface conductive hollow fiber membrane possessed good anti-fouling ability in AnMBR, and provided an alternative membrane material for AnMBR application.
25. 题目: Different forms of carbon, nitrogen, and phosphorus influence ecosystem stoichiometry in a north temperate river across seasons and land uses
期刊: Limnology and Oceanography
作者: Stéphanie Shousha, Roxane Maranger, Jean‐François Lapierre
摘要: Natural and human features on land result in differential loadings of carbon (C), nitrogen (N), and phosphorus (P) to rivers that influence within ecosystem processing. However, little is known about how land use, together with seasonal changes in climate and hydrology, influence the relative proportions of C, N, and P in rivers. To evaluate the spatial and temporal patterns in ecosystem-level C: N: P stoichiometry, we sampled 13 sites once per season for 3 yr along the main stem of a north temperate river with winter ice-cover that flows across a gradient of forested, urban, and agricultural landscapes. We found that C concentrations were rather stable along the continuum, whereas N and P rapidly increased downstream due to urban and agricultural land uses. The flow-weighted C: N: P ecosystem stoichiometry ranged from 2319: 119: 1 in the most upstream site to 368: 60: 1 at the outlet. The dominant form of N generally shifted from dissolved organic nitrogen in upstream forested reaches to nitrate in more impacted, downstream reaches, and winter stoichiometry was enriched in inorganic N and dissolved P forms. Concentrations of all three elements were generally lower in spring during year-high flow due to dilution. The spatial and temporal variation in stoichiometry in this north temperate river covered much of the range previously observed between litter ratios and the Redfield ratio. This suggests that even moderate human impacts can have profound effects on riverine ecosystem stoichiometry, and that these effects are modulated by seasonal trends in temperature and hydrology.
26. 题目: Facile synthesis of Fe-modified lignin-based biochar for ultra-fast adsorption of methylene blue: Selective adsorption and mechanism studies
期刊: Bioresource Technology
作者: Yongchang Sun, Tingting Wang, Caohui Han, Xintian Lv, Lu Bai, Xiaoyin Sun, Pengfei Zhang
摘要: A novel Fe-modified lignin-based biochar (Fe-LB) was fabricated via a facile one-step carbonization method for methylene blue (MB) removal from wastewater. Fe-LB exhibited a high specific surface area (885.97 m2/g) and micropore volume (0.3203 m3/g), and demonstrated high affinity for MB with the maximum adsorption capacity of 2.7-fold by Fe-LB than LB. It was found that quick adsorption could be achieved in 15 min with the MB removal efficiency of 100% and adsorption capacity reached 200 mg/g. Selective adsorption studies indicated that Fe-LB preferentially adsorbed MB in high salt and multiple dye systems (binary, ternary, and quaternary) over a wide pH range from 2 to 12. The removal efficiency of CR was greatly improved due to the synergistic effect between MB and CR in the binary system. This work demonstrated that Fe-LB can effectively remove dye contaminants and possessed great potential in the treatment of MB polluted dye wastewater.
27. 题目: Effects of vegetation restoration types on soil nutrients and soil erodibility regulated by slope positions on the Loess Plateau
期刊: Journal of Environmental Management
作者: Lingbo Dong, Jiwei Li, Yu Zhang, Mengyao Bing, Yulin Liu, Jianzhao Wu, Xuying Hai, Ao Li, Kaibo Wang, Puxia Wu, Zhouping Shangguan, Lei Deng
摘要: Soil degradation is significantly increased driven by soil nutrient loss and soil erodibility, thus, hampering the sustainable development of the ecological environment and agricultural production. Vegetation restoration has been widely adopted to prevent soil degradation given its role in improving soil nutrients and soil erodibility. However, it is unclear which vegetation type has the best improving capacity from soil nutrient and soil erodibility perspectives. This study selected three vegetation restoration types of grasslands (GL), shrublands (SL), and forestlands (FL) along the five slope positions (i.e., top, upper, middle, lower, and foot slope), to investigate the effects of vegetation restoration types on soil nutrients and soil erodibility. All vegetation restoration types were restored for 20 years from croplands (CL). We used comprehensive soil nutrient index (CSNI) and comprehensive soil erodibility index (CSEI) formed by a weighted summation method to reflect the effect of vegetation restoration on the improving capacity of soil nutrient and erodibility. The results showed the vegetation types with the highest comprehensive soil quality index (CSQI) at the top, upper, middle, lower and foot slope were FL (1.92), FL (1.98), SL (2.15), FL (2.37) and GL (3.93), respectively. When only one vegetation type was considered on the entire slope, SL (0.59) and FL (0.59) had the highest CSNI, the SL had the lowest CSEI (0.34) and the highest CSQI (1.89). The CSNI was mainly influenced by soil structure stability index (SSSI), sand content, silt + clay particles, and CSEI was controlled by soil organic matter (SOM), macroaggregates and microaggregates. Moreover, the CSQI was influenced by pH, silt and clay content, and biome coverage (BC). The study suggested the SL were advised as the best vegetation restoration type on the whole slope from improving soil nutrients and soil erodibility.
28. 题目: Dynamics of biofilms on different polymeric membranes – A comparative study using five physiologically and genetically distinct bacteria
期刊: Journal of Membrane Science
作者: Hira Waheed, Ch Tahir Mehmood, Yongyu Yang, Weiyu Tan, Saisai Fu, Yeyuan Xiao
摘要: Biofilm formation potential of anaerobic microbes on polymeric membranes is widely acknowledged but barely investigated. In this study, the biofilm dynamics of five bacterial isolates from anaerobic sludge, against eight different polymeric membranes, was systematically characterized via scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Fibrous surfaces, i.e., polytetrafluoroethylene, polypropylene and polyvinyl chloride were more favorable for biofilms than the leveled porous substratum. Cellulose-based membranes, especially cellulose nitrate, and cellulose acetate-cellulose nitrate, with a relatively hydrophilic surface showed the highest resistance to biofilms among all membranes. The growth stage played a vital role in biofilm formation, as differences in biofilms of the same strain, in terms of biofilm volumes, thickness and surface coverage, across 8 different substrata, were only observed for mature biofilms. While for early-stage biofilms, the same biomass volume was developed regardless of substratum. This was largely attributed to the interactions between substrata and extracellular polymeric substances (EPS), which was not a prerequisite for initial bacterial adhesion but crucial for cell cohesion in mature biofilms, and thus deciding the morphology and thickness of mature biofilms. These findings highlight that quenching EPS production and diminishing EPS-substratum interaction are the optimum fouling control strategies in membrane-based water treatment systems.
29. 题目: Distinct uptake and accumulation profiles of triclosan in youdonger (Brassica campestris subsp. Chinensis var. communis) under two planting systems: Evidence from 14C tracing techniques
作者: Enguang Nie, Haiyan Wang, Yan Chen, Yuhui Lu, Kashif Akhtar, Muhammad Riaz, Sufen Zhang, Zhiyang Yu, Qingfu Ye
摘要: Triclosan is a widely used biocide against microorganisms and is ubiquitously distributed in the environment. Triclosan can be accumulated into plants from soil and hydroponic media. However, little information is currently available on the comparative fate of triclosan in plants under soil and hydroponics cultivation conditions and factors governing uptake. Therefore, this study was designed to comparatively elucidate the uptake mechanism of 14C-triclosan in youdonger (Brassica campestris subsp. Chinensis var. communis) grown under different soils and hydroponics and clarify dominant uptake factors. Results showed that 77.2% of 14C were accumulated in youdonger grown in a hydroponic system, while only 1.24%–2.33% were accumulated in the two soil-planting systems. In addition, the bioconcentration factor (BCF) of 14C-triclosan in soil-plant systems was approximately 400-fold smaller than that in the hydroponics. In the soil-planting system, a strong linear correlation was found between concentrations of triclosan in soil pore water and youdonger plant (R2 > 0.85, p < 0.01) at different incubation times. Therefore, triclosan in pore water might be a good indicator to estimate its accumulation in plants and is significantly affected by soil pH, clay, and organic matter contents. The estimated average dietary intakes of triclosan for youdonger grown in hydroponic and soil-planting systems were estimated to be 1.31 ng day−1 kg−1 and 0.05–0.12 ng day−1 kg−1, respectively, much lower than the acceptable dietary intakes of triclosan (83 μg day−1 kg−1), indicating no significant human health risks from youdonger consumption. This study provided insights into uptake routes of triclosan into youdonger plants from both soil and hydroponic systems, bioavailability of triclosan in different soils, and further assessment of human exposure to triclosan from youdonger.
30. 题目: Rhizosphere Bacterial Community Structure of Three Minor Grain Crops: A Case Study from Paired Field Sites in Northern China
期刊: Land Degradation & Development
作者: Lixin Tian, Yunhao Wang, Junxue Yang, Liyuan Zhang, Baili Feng
摘要: Rhizosphere bacteria are critical to plant health and ecological functioning. However, our understanding of rhizosphere bacterial community turnover and co-occurrences with minor grain crops remains limited, especially at regional scales. Herein, we compared the turnover and networks of foxtail millet, proso millet, and sorghum rhizosphere bacterial communities across nine paired fields in northern China. Remarkable differences in community composition, diversity between three minor grain crops, and the influence of regions on these indicators was greater than that of crop types. Community richness of three minor grain crops showed a unimodal curve with latitude increased . Compared to spatial factors, environmental variables had greater effects on the rhizosphere bacterial community turnover in three minor grain crops. Edaphic variables were more important than climatic variables for rhizosphere bacterial community composition in foxtail millet fields. Additionally, soil organic matter (OM) and total nitrogen (TN) were the key factors influencing the turnover of rhizosphere communities in foxtail millet and sorghum. In contrast, pH and TN were important factors influencing the turnover of rhizosphere communities in proso millet. Rhizosphere bacterial networks were more closely interconnected in proso millet fields than in the other two crops, showing the lower average path length and diameter, greater average clustering and graph density. Additionally, Proteobacteria, Actinobacteria, and Acidobacteria played major roles in the rhizosphere bacterial network structures and were predicted to maintain generalist metabolic diversity. These findings provide new insights for expanding our knowledge of the biogeography and coexistence theory of minor grain crop ecosystems at a large scale.
31. 题目: Characteristics of algae-derived biochars and their sorption and remediation performance for sulfamethoxazole in marine environment
期刊: Chemical Engineering Journal
作者: Man Zhao, Xiaohan Ma, Xinrui Liao, Siyu Cheng, Qiang Liu, Hefang Wang, Hao Zheng, Xiaoyun Li, Xianxiang Luo, Jian Zhao, Fengmin Li, Baoshan Xing
摘要: The performance of algae-derived biochars (ABCs) on sorption and remediation of antibiotic pollution in marine environment is poorly understood. A batch of biochars were produced from two marine algae waste (Enteromorpha prolifera and seaweed residuals) at 300–700 °C (EM300–700 and SW300–700) to investigate their sorption of sulfamethoxazole (SMX) in seawater, as well as their performance in in-situ remediation of SMX polluted marine sediment. Regardless the heating temperature (HTT), ABCs with relatively low C contents (29.6–37.4%), but high contents of O (16.6–28.9%) and N (0.75–3.48%), possessed lower surface area, but more abundant minerals (ash content 33.5–63.5%), richer heteroatom-containing functional groups than the terrestrial plant silvergrass-derived biochars (SGBCs). The maximum sorption capacities of ABCs increased from 2896–4212 mg kg−1 to 4874–4879 mg kg−1 as the HTT increased from 300 to 700 °C, higher than those of the SGBCs (1017–3515 mg kg−1). SMX sorption on the ABCs was dominantly through cation bridging, followed by negative charge-assisted H-bond, π-π electron donor-acceptor interaction, and pore filling. Moreover, the in situ mixing and capping of SW700 effectively decreased SMX bioavailability in the sediment, equivalent to a commercial activated carbon. These results provide the strategies for in-situ remediation of antibiotic-contaminated marine sediments using designer biochars from marine algae waste.
32. 题目: A Study of Salvaged Cyanobacteria Slurry Treatment Using Liquefied Dimethyl Ether: Dehydration and Organic Matter Extraction
期刊: ACS Sustainable Chemistry & Engineering
作者: Zhuo Li, Chenyu Wang, Wei Zhu, Biao Mu, Sipeng Chen, Jipeng Sun
摘要: Liquefied dimethyl ether (L-DME) was used to dehydrate salvaged cyanobacteria slurry (SCS) and extract its organic matter. The dehydration rate and organic matter extraction efficiency were determined by mixing L-DME with SCS in a sealed reactor for 0–25 min, and the amount of solvent was 6–39 times that of SCS at a stirring rate of 0–800 rpm. Free water in SCS was removed entirely at an L-DME amount of 9 times, and then bound water was gradually removed with an increase in L-DME dosage, with a final SCS lowest moisture content of 16.64% at an L-DME amount of 39 times. Moreover, L-DME extracted 8.72%–21.15% of the organic matter from SCS, with almost complete lipid extraction. The phosphorus and nitrogen were also extracted because they mainly exist in phospholipids and proteins. Subsequently, the solid residue and liquid product were characterized, with fatty acids and plasticizers found in the liquid product. The dehydration rate and organic matter extraction efficiency were also investigated using ethanol as adjuvant of L-DME, with ethanol serving as an adjuvant. The performance of dehydration and organic matter extraction from SCS using L-DME was evaluated to explore the feasibility of applying this process to SCS treatment.
33. 题目: Ecology and climate sensitivity of a groundwater-fed lake on subtropical North Stradbroke Island (Minjerribah), Queensland, Australia over the last 7500 years
期刊: Journal of Paleolimnology
作者: Charles Maxson, John Tibby, Cameron Barr, Jonathan Tyler, Melanie Leng, Barry Lomax, Jonathan Marshall, Glenn McGregor, Cameron Schulz, Haidee Cadd, Geraldine Jacobsen
摘要: Lake sediments are important archives of past climate variability and lake responses to climate. In order to accurately infer past climates, it is necessary to understand, and account for, the ecological processes that affect the record of indicators preserved in lake sediment. This is particularly the case with respect to the concentration of carbon and nitrogen (TOC, TN, and calculated C:N), and the stable isotope composition of organic matter preserved in lake sediments. These are common, yet ambiguous, tracers of environmental change. Ideally, palaeoenvironmental reconstructions using the concentration and isotope composition of organic matter should be grounded in a detailed understanding of the sources of the organic material. This study documents the history and evolution of Blue Lake, an environmentally and culturally important oligotrophic, groundwater window lake on North Stradbroke Island, Queensland, Australia. We utilise organic matter δ13C, TOC, TN, and C:N from a 2.4 m sediment core with a basal age of 7.5 cal kyr BP, to investigate changing organic matter sources as a measure of the climate sensitivity of Blue Lake. This interpretation is supported by data from contemporary algae, aquatic and terrestrial plants, and catchment soils. We show that lake nutrient dynamics drove an increase in algal biomass at 4.2 cal kyr BP. This change coincides with a widely documented intensification of the El Niño-Southern Oscillation, which we infer to have influenced lake nutrient concentrations by reducing groundwater throughflow. Climatic changes resulted in marked changes in lake primary productivity, despite relatively little turnover of the lake diatom flora and catchment vegetation. This suggests that south-east Queensland dune lakes are sensitive to climate changes and helps to refine past and future palaeoclimate research using sediments from these lakes. It also indicates that increased nutrient concentrations in Blue Lake may result from projected changes in 21st Century climate.
34. 题目: Priming effects in the rhizosphere and root detritusphere of two wet-grassland graminoids
期刊: Plant and Soil
作者: Eva Kaštovská, Julian Cardenas-Hernandez, Yakov Kuzyakov
摘要: Aims The rhizosphere and root detritusphere are hotspots of microbial activity, where root-derived inputs induce intensive priming effects (PE) on soil organic carbon (SOC) decomposition. These conditions for induced PE differ between rhizosphere and detritusphere and are modified by plant traits. Methods Continuous labelling with 13C-depleted CO2 allowed for the partitioning of plant and soil C sources of CO2 efflux and the investigation of the PE in the rhizosphere and detritusphere of slow-growing conservative Carex acuta and fast-growing acquisitive Glyceria maxima. Results Glyceria allocated more C into the soil, induced higher microbial activity and a larger portion of active microorganisms, and depleted mineral N stronger than Carex. Its rhizosphere PE was 2.5 times stronger than that of Carex. Root residues (detritusphere) induced negative PE at the early stage of decomposition (1–9 months). The depletion of available organic substances in the detritusphere of more easily decomposable Glyceria roots resulted in positive PE after 3 months. The PE in the detritusphere of N-poorer Carex roots was more intensive but started after 9 months. Conclusions The rhizosphere PE was positive and stronger than the detritusphere PE, which switched from initially negative to positive PE after depletion of available substances during few months. More productive species with faster N-uptake and higher belowground C input (here Glyceria) induce larger rhizosphere PE than slower-growing species (here Carex). The N-rich Glyceria roots decompose faster than N-poor roots of Carex and, consequently, have a lower impact on SOC dynamics and induced a smaller positive detritusphere PE. Graphic abstract
35. 题目: Oxidant-reactive carbonous moieties in dissolved organic matter: selective quantification by oxidative titration using chlorine dioxide and ozone
期刊: Water Research
作者: Joanna Houska, Elisabeth Salhi, Nicolas WAlpen, Urs von Gunten
摘要: The application of oxidants for disinfection or micropollutant abatement during drinking water and wastewater treatment is accompanied by oxidation of matrix components such as dissolved organic matter (DOM). To improve predictions of the efficiency of oxidation processes and the formation of oxidation products, methods to determine concentrations of oxidant-reactive phenolic, olefinic or amine-type DOM moieties are critical. Here, a novel selective oxidative titration approach is presented, which is based on reaction kinetics of oxidation reactions towards certain DOM moieties. Phenolic moieties were determined by oxidative titration with ClO2 and O3 for five DOM isolates and two secondary wastewater effluent samples. The determined concentrations of phenolic moieties correlated with the electron-donating capacity (EDC) and the formation of inorganic ClO2-byproducts (HOCl, ClO2−, ClO3−). ClO2-byproduct yields from phenol and DOM isolates and changes due to the application of molecular tagging for phenols revealed a better understanding of oxidant-reactive structures within DOM. Overall, oxidative titrations with ClO2 and O3 provide a novel and promising tool to quantify oxidant-reactive moieties in complex mixtures such as DOM and can be expanded to other matrices or oxidants.
36. 题目: Redox-Active Moieties in Dissolved Organic Matter Accelerate the Degradation of Nitroimidazoles in SO 4 •– -Based Oxidation
期刊: Environmental Science & Technology
作者: Yangjian Zhou, Yang Wu, Yu Lei, Yanheng Pan, Shuangshuang Cheng, Gangfeng Ouyang, Xin Yang
摘要: The presence of dissolved organic matter (DOM) is known to inhibit the degradation of trace organic contaminants (TrOCs) in SO4•–-based advanced oxidation processes (AOPs) due to filtering of the photochemically active light and radical scavenging effects. This study revealed an unexpected contribution for DOM in the degradation of nitroimidazoles (NZs) in the UV/persulfate AOP. The apparent second-order rate constants of NZs with SO4•– increased by 2.05 to 4.77 times in the presence of different DOMs. The increments were linearly related to the total electron capacity of DOM. Quinone and polyphenol moieties were found to play a dominant role. The reactive species generated from SO4•–’s oxidation of DOM, including semiquinone radical (SQ•–) and superoxide (O2•–), were found to react with NZs via Michael addition and O2•– addition. The second-order rate constants of tinidazole with SQ•– is determined to be (5.69 ± 0.59) × 106 M–1 s–1 by laser flash photolysis. Reactive species potentially generated from DOM may be considered in designing processes for the abatement of different types of TrOCs.
37. 题目: Goethite modified biochar simultaneously mitigates the arsenic and cadmium accumulation in paddy rice (Oryza sativa) L
期刊: Environmental Research
作者: Muhammad Kashif Irshad, Ali Noman, Yang Wang, Yingjie Yin, Chong Chen, Jianying Shang
摘要: Cadmium (Cd) and arsenic (As) contamination of paddy soils is a serious global issue because of the opposite geochemical behavior of Cd and As in paddy soils. Rice plant (Oryza sativa L.) cultivation in Cd- and As- contaminated paddy soil is regarded as one of the main dietary cause of Cd and As entry in human beings. This study aimed to determine the impact of goethite-modified biochar (GB) on bioavailability of both Cd and As in Cd- and As- polluted paddy soil. Contrary to control and biochar (BC) amendments, the application of GB amendments significantly impeded the accumulation of both Cd and As in rice plants. The results confirmed an obvious reduction in Cd and As content of rice grains by 85% and 77%, respectively after soil supplementation with GB 2% amendment. BC 3% application minimized the Cd uptake by 59% in the rice grains as compared to the control but exhibited a little impact on As accumulation in rice grains. Sequential extraction results displayed an increase in immobile Cd and As fractions of the soil by decreasing the bioavailable fractions of both elements after GB treatments. Fe-plaque formation on the root surfaces was significantly variable (P ˂ 0.05) among all the amendments. GB 2% treatment significantly increased the Fe content (10 g kg−1) of root Fe-plaque by 48%, which ultimately enhanced the sequestration of Cd and As by Fe-plaque and minimized the transport of Cd and As in rice plants. Moreover, GB treatments significantly changed the relative abundance of the microbial community in the rice rhizosphere and minimized the metal(loid)s mobility in the soil. The relative abundance of Acidobacteria, Firmicutes and Verrucomicrobia increased with GB 2% treatment while those of Bacteroidetes and Choloroflexi decreased. Our findings confirmed improvement in the rice grains quality regarding enhanced amino acid contents with GB application. Overall, the results of this study demonstrated that GB amendment simultaneously alleviated the Cd and As concentrations in edible parts of rice plant and provided a new valuable method to protect the public health by effectively remediating the co-occurrence of Cd and As in paddy soils.
38. 题目: Extreme Molecular Complexity Resulting in a Continuum of Carbonaceous Species in Biomass Burning Tar Balls from Wildfire Smoke
期刊: ACS Earth and Space Chemistry
作者: Matthew A. Brege, Swarup China, Simeon Schum, Alla Zelenyuk, Lynn R. Mazzoleni
摘要: Biomass burning emits a wide range of carbonaceous particles into the atmosphere and has negative impacts on human health and the Earth’s radiative balance. Nonvolatile spherical organic aerosol particles, commonly known as tar balls, represent one of the most abundant particles in aged biomass burning smoke. However, the detailed molecular level composition of ambient tar balls is largely unknown but critical to assess their environmental impacts. Ambient aerosol samples collected during a wildfire event, which were ∼90% tar balls by number fraction, were analyzed using ultrahigh-resolution Orbitrap Elite mass spectrometry with four complementary ionization modes. Our results show the molecular composition of tar balls to be complex, composed of over 10,000 molecular formulas. Model estimated saturation mass concentrations and relative humidity-dependent glass-transition temperatures were consistent with low volatility and solid morphology as expected for tar balls. Room-temperature evaporation kinetics showed that these particles retained ∼90% of their volume after 24 h of evaporation. The molecular complexity detected here signifies a continuum of carbonaceous species, ranging from C3 to C45 with continuous ranges of oxygenation and hydrogen saturation for each Cn. Approximately 24% of molecular formulas were estimated to be highly aromatic, which could indicate chemical compounds with negative health effects and which may contribute to visible light absorption. The carbon continuum observed here has significant implications for the molecular characterization of atmospheric organic matter. The level of complexity detected here should not be ignored in future studies, and we demonstrate that multiple analytical methods may be required to suitably interpret this complexity on a molecular level.
39. 题目: NH2-MIL-125 (Ti)/biochar fibers for enhanced direct dyes adsorption
期刊: Journal of Environmental Chemical Engineering
作者: Qiushi Jiang, Zhaolian Han, Xiaobin Yu, Yafeng Yuan, Yating Ren, Jiapeng Li, Chunli Zhao, Zhiqiang Cheng
摘要: A novel adsorbent composite was synthesized by combining amino-functionalized MIL-125 (Ti) with carbonized wormwood (CW), and used to remove six direct dyes. The effect of carbon matrix type on the properties of the composites was investigated. The samples were characterized by chemical, morphological, thermal behavior, specific surface area, and pore diameter analysis. NH2-MIL-125 (Ti)/CW exhibits good crystallinity, high specific surface area, multi-pore size distribution, thermal stability and more active groups compared with carbonized cotton fiber and activated carbon as the matrix. Under optimal conditions, the adsorption process of NH2-MIL-125 (Ti)/CW on Direct Yellow R and Direct Dark Green NB is consistent with the Freundlich model and pseudo-second-order kinetic model. The adsorption capacity of NH2-MIL-125 (Ti)/CW is 255.0 and 296.7mg/g, which is superior to 140.4 and 220.3mg/g of NH2-MIL-125 (Ti), 58.9 and 97.8mg/g of CW and other composite adsorption materials in a distilled water system. It is worth mentioning that NH2-MIL-125 (Ti)/CW can even achieve adsorption removal effects of 470.8 and 500.0mg/g at pH=2. This work may provide a theoretical reference for the application of biochar and metal-organic frameworks in the field of wastewater treatment.
40. 题目: Biochar as soil amendment: Syngas recycling system is essential to create positive carbon credit
期刊: Science of The Total Environment
作者: Ronley C. Canatoy, Seung Tak Jeong, Snowie Jane C. Galgo, Pil Joo Kim, Song Rae Cho
摘要: Biochar utilization is accepted as the most cost-effective practice to mitigate global warming via increase in soil C stock. However, its utilization effect on greenhouse gas (GHG) fluxes was evaluated only within land application without considering industrial processes. To evaluate the net effect of biochar utilization on global warming within whole system boundary, swine manure-saw dust mixture was pyrolyzed under four different temperatures, and GHG fluxes were characterized under with/without syngas recycling systems. To determine GHG fluxes from biochar amended soil, 40 Mg ha−1 of biochar was mixed with soil and incubated under the flooded and the dried soil conditions. Finally, the effect of biochar utilization was generalized using net global warming potential (GWP) from industrial process to land application. Under without syngas recycling system, huge amounts of GHGs were emitted during pyrolysis, and GHG fluxes highly increased with increasing pyrolysis temperature, due to direct and indirect GHG emissions from feedstock combustion and electricity, respectively. However, syngas recycling system removed most of GHGs, except for direct N2O and indirect GHG emissions from electricity. Biochar application was very effective to mitigate GHG emissions within soil system boundary, and biochar produced at higher pyrolysis temperature showed higher effectivity in decreasing GHG fluxes. Within the whole system boundary from pyrolysis to soil application, without the installation of syngas recycling system, raw manure application was more effective than biochar to reduce GHG emissions, regardless of soil water conditions. However, with the installation of syngas recycling system, biochar application was much more effective than fresh manure to decrease GHG fluxes. Biochar produced at higher temperature had higher effectivity to mitigate global warming impacts. In conclusion, to functionally mitigate global warming in soils, biochar should be produced in pyrolysis reactors equipped with syngas recycling system under higher temperature.