论文检索

总访问量：5894984次

总访客量：421087人

所有论文

17361. 题目: Soil organic carbon storage, distribution, and influencing factors at different depths in the dryland farming regions of Northeast and North China
文章编号: N21121513
期刊: CATENA
作者: Zhiqing Zhuo, Qianqian Chen, Xianglin Zhang, Songchao Chen, Yuxuan Gou, Zhongxiang Sun, Yuanfang Huang, Zhou Shi
更新时间: 2021-12-15
摘要: The knowledge of the spatial distribution of soil organic carbon (SOC) and of its influencing factors is crucial for understanding the global carbon cycle. Although the influence of climate, soil properties, and soil management on the SOC content has been extensively explored, their relative importance remains unclear, especially under dryland farming. Herein, we investigated the SOC density (SOCD) at different depths (0–10, 10–20, 20–30, and 30–40 cm) across an area of 37.79 × 104 km2 (420 sites) located in the dryland farming regions of Northeast and North China. The total SOC storage (SOCS) was estimated to be 1922.38 Tg, with a mean density of 5.78 kg C m−2 for the entire area. The three soil groups with the largest SOCS were Fluvo-aquic, Black, and Chernozem soils, accounting for 63.34% of the total SOCS in the study area. Overall, both the SOCD and SOCS increased from southwest to northeast at all investigated depths. A structural equation model was used to distinguish direct from indirect effects of different factors on SOCD. Soil properties (e.g., bulk density and pH) and natural conditions (e.g., mean annual temperature and mean annual precipitation) were found to be the main factors controlling the SOCD variation at depths of 10–20, 20–30, and 30–40 cm. However, the total (direct and indirect) effect of soil management on SOCD at a 0–10 cm depth was greater than that of natural conditions, and smaller than that of soil properties. With increasing soil depth, the total effect of natural conditions on SOCD changed from –0.33 to –0.58, whereas the indirect effect of soil management decreased from 0.47 to 0. These results indicate that compared with environmental factors, soil management practices such as tillage and fertilization had a greater influence on SOCD in the surface soil of dryland. Our study provides a valuable reference for future research on the long-term evolution of SOC in dryland farming regions.

17362. 题目: Growth and Anchorage of Myriophyllum spicatum L. in Relation to Water Depth and the Content of Organic Matter in Sediment
文章编号: N21121512
期刊: Frontiers in Environmental Science
作者: Liang He, Rui Wang, Huan Zhang, Meng Zhang, Ying Liu, Guorong Zhu, Te Cao, Leyi Ni, Gang Ge
更新时间: 2021-12-15
摘要: A large body of evidence suggests that the physical and chemical characteristics of the sediment in lakes that have undergone eutrophication have been significantly altered. However, the effects of alterations in sediments on submersed macrophytes remain unknown. In this study, we present the results of an outdoor experiment that examined how the growth and anchorage of the widespread submersed macrophyte Myriophyllum spicatum L. responded to the enrichment of organic matter in the sediments and whether water depth affects these responses. We found that low levels of enrichment with organic matter (≤7%) enhanced the growth of M. spicatum . In contrast, high levels of enrichment with organic matter (from 12 to 18%) slightly inhibited its growth. Although the anchorage force of M. spicatum slightly decreased with an increase in the content of organic matter in the sediment, it was much higher than the hydraulic drag force on plants at a relatively high current velocity, indicating that the plants were unlikely to be uprooted in these sediments. The water depth did not alter the responses of growth and anchorage of M. spicatum to enrichment with organic matter. Our results suggest that M. spicatum could be a potential species to restore eutrophic lakes, since it can grow well and anchor stably in sediments with relatively high organic matter and manage low light stress.

17363. 题目: Removal of decabromodiphenyl ethane (DBDPE) by BC/nZVI in the soil: Kinetics, pathways and mechanisms
文章编号: N21121511
期刊: Journal of Environmental Chemical Engineering
作者: Cong Lu, Jiang Wan, Xiao Chen, Wei Zhang, Kuangfei Lin, Cheng Peng
更新时间: 2021-12-15
摘要: Decabromodiphenyl ethane (DBDPE), as a crucial novel brominated flame retardant, has been widely used in the world, of which the accumulation in soil also poses a significant threat to human health. Biochar (BC) and nano-zero-valent iron (nZVI) are environmental-friendly remediation materials for contaminants. In this study, the biochar-supported nZVI (BC/nZVI) particles were synthesized using bagasse at 600 °C under nitrogen protection and then were used to remove DBDPE in a soil system. The results indicated that BC was a good carrier for nZVI due to the decrease of agglomeration. The highest removal efficiency of BC/nZVI was up to 86.91% at 24 h at a mass ratio of 2:1 (BC:nZVI), which was much higher than BC or nZVI alone. The degradation kinetics of BC/nZVI to DBDPE followed the pseudo-first-order reaction model well. DBDPE was firstly removed by the adsorption of BC from soil via π-π interactions and hydrogen bonds, and then was oxidized by ·OH generated from BC forming DBDPE-C=O (DP-1). Subsequently, the debromination of DP-1 gradually occurred by the ·H from surface hydrolysis of nZVI attacking the bromide on the benzene ring. This technology may act as a promising way for the remediation of highly DBDPE-contaminated soil.

17364. 题目: Groundwater-surface water interactions and flux of organic matter and nutrients in an urban, Mediterranean stream
文章编号: N21121510
期刊: Science of The Total Environment
作者: Natalie Mladenov, Daniel Parsons, Alicia M. Kinoshita, Federick Pinongcos, Margot Mueller, Denise Garcia, David A. Lipson, Lorelay Mendoza Grijalva, Thomas Zink
更新时间: 2021-12-15
摘要: The chemical quality of dissolved organic matter (DOM) and the speciation of nitrogen exported from urban catchments is of great importance to biogeochemical cycling in riverine and coastal receiving waters. Many urban streams in Mediterranean climates have a flashy hydrologic regime, which would suggest a rapid pulsing and shunting of solutes downstream. However, the role of these systems both as passive pipes for solute transport or as reactors for DOM and nutrient transformation is still an open question for urban, Mediterranean streams. To address this question, we evaluated changes in concentrations of inorganic and organic solutes and DOM optical properties in Alvarado Creek, a perennially-flowing, urban, first-order tributary of the San Diego River in San Diego, CA, USA, during dry weather (baseflow) conditions and during four storm events in 2016–2018. Chloride and sulfate concentrations corroborate the supposed saline groundwater supply that maintains perennial flow and brackish nature in this urban stream. During dry weather, high proportions of protein-like fluorescent component (AC4) and downstream decreases in total dissolved nitrogen (TDN) and nitrate imply in-stream processing (nitrification and denitrification). By contrast, storm hysteresis curves indicate that the supply of DOM and TDN was not exhausted over the duration of a storm event, whereas nitrate was eventually depleted, presumably because nitrification could not keep up with the export of nitrate from source areas. Rapid decreases in chloride during the storm hydrograph coincided with a shift in specific ultraviolet absorbance (SUVA) and fluorescence index (FI) to more terrestrially-derived and aromatic carbon sources, most likely from interflow of stormwater through vadose zone soils. On an annual basis, the export of microbially-derived DOM during dry weather was higher than the export of terrestrially-derived DOM during storm events; both represent important carbon inputs to coastal waters.

17365. 题目: Application of sludge biochar combined with peroxydisulfate to degrade fluoroquinolones: Efficiency, mechanisms and implication for ISCO
文章编号: N21121509
期刊: Journal of Hazardous Materials
作者: Zhihuang Fang, Zilin Zhou, Gang Xue, Yang Yu, Qi Wang, Biran Cheng, Yinglong Ge, Yajie Qian
更新时间: 2021-12-15
摘要: Peroxydisulfate (PDS) is increasingly used for in situ chemical oxidation (ISCO) of organic pollutants in groundwater, but the efficient and applicable activator is still scarce. In this study, sludge-derived biochar (SDBC) was prepared by pyrolysis to activate PDS, which could effectively degrade the fluoroquinolone antibiotics (FQs, levofloxacin, enrofloxacin, norfloxacin and ciprofloxacin). Compared with pig manure and corn straw derived biochar, SDBC showed higher efficiency in PDS activation. Singlet oxygen (1O2) was identified as the major reactive species, and the surface-bonded radicals also contributed to the FQs degradation. The selective oxidation of FQs by 1O2 was first reported, which followed the trend of enrofloxacin ~ levofloxacin > norfloxacin ~ ciprofloxacin. The C=O and Fe2+ on SDBC were the dominant reactive sites for PDS activating. Products analysis revealed that FQs degradation proceeds via the cleavage of the piperazine ring, breaking of the quinolone ring, decarboxylation, and defluorination. Moreover, the tertiary amine of N (4) on enrofloxacin was more reactive towards singlet oxygen than the secondary amine of N (4) on ciprofloxacin, inducing the faster degradation and de-toxicity of enrofloxacin in the reaction system. SDBC showed high reusability in PDS activation and negligible metals leachates were detected. The column study proved the efficiency of PDS/SDBC in groundwater remediation.

17366. 题目: Grassland management strategies influence soil C, N, and P sequestration through shifting plant community composition in a semi-arid grasslands of northern China
文章编号: N21121508
期刊: Ecological Indicators
作者: Lingling Chen, Taogetao Baoyin, Fangshan Xia
更新时间: 2021-12-15
摘要: Current studies regarding the effects of grassland management strategies on the soil nutrient cycle have mostly focused on soil organic carbon (SOC). Less is known about the responses of SOC, total nitrogen (TN), and total phosphorous (TP) stocks to grassland management strategies at different soil depths. We therefore quantified vertical variations in SOC, TN, and TP stocks as well as controlling factors under three grassland management strategies (i.e., enclosure control, grazing twice a year, grazing combined with mowing) in 2014 and 2017 in a semi-arid grassland of northern China. We found that grazing twice a year and grazing combined with mowing led to an increase in plant production as well as soil C and N sequestration during 2014 to 2017. Changes in plant aboveground biomass (AGB), belowground biomass (BGB), and root-to-shoot ratio (R:S) all exerted significant positive effects on changes in soil C and N sequestration in the surface soil layer (0–30 cm), while changes in AGB and plant community composition played a more important role in mediating soil C, N, and P sequestration in response to grassland management strategies in the subsoil layer (30–100 cm). Specifically, grassland management strategies influence soil C, N, and P sequestration capacity by altering plant community composition. The results of this study provide new insights into the response mechanisms of plants and soils to grassland management practices and offer a range of new possible strategies that might be applied to the effective management of semi-arid grasslands.

17367. 题目: Natural dissolved organic matter (DOM) affects W(VI) adsorption onto Al (hydr)oxide: Mechanisms and influencing factors
文章编号: N21121507
期刊: Environmental Research
作者: Lei Lu, Wenkai Rao, Yuyan Song, Ming Lei, Boqing Tie, Huihui Du
更新时间: 2021-12-15
摘要: Tungsten (W) is a contaminant with health implications whose environmental behaviors are not understood well. Sorption to mineral surfaces is one of the primary processes controlling the mobility and fate of W in soils, sediments, and aquifers. However, few papers published hitherto have not yet figured out the influences of dissolved organic matter (DOM) on this process. Here, we examine W(VI) adsorption behaviors onto Al (hydr)oxide (AAH) in the presence or absence of DOM derived from plant rhizosphere, using batch experiments coupled with X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The morphology and functional group analyses results show that DOM can facilitate the aggregation of AAH and block surface Al–OH groups. Coexisting DOM inhibits W(VI) adsorption onto AAH at acidic to neutral pH (4–7), and the presence of either Na + or PO43− can exert a completely different impact on W(VI) adsorption. XPS and FTIR characterizations further demonstrate surface W complexes with the Al–OH groups of AAH and carboxyl groups of DOM. There is no reduction of W(VI) during the adsorption processes, and poly-tungstate species are formed on the surface of both AAH and AAH–DOM coprecipitates. This study provides the first evidence of the roles of natural DOM on W sequestration at the mineral-water surface, which has an important implication for the prediction of the migration and bioavailability of W in natural environments.

17368. 题目: Nonlinear enhancement of radiative absorption by black carbon in response to particle mixing structure
文章编号: N21121506
期刊: Geophysical Research Letters
作者: Yuanyuan Wang, Weijun Li, Jin Huang, Lei Liu, Yuner Pang, Cenlin He, Fengshan Liu, Dantong Liu, Lei Bi, Xiaoye Zhang, Zongbo Shi
更新时间: 2021-12-15
摘要: Black carbon (BC) strongly absorbs solar radiation, contributing to global warming. Absorption enhancement of BC particles is difficult to quantify due to an inadequate representation of their complex morphology and mixing structures, as well as interaction with radiation. Here we apply a 3D method accounting for detailed BC mixing structures to predict the absorption enhancement of individual BC particles (Eabs) and the total BC particle population (Eabs, bulk). The diverse range of mixing structures in individual BC particles leads to variable Eabs that could be hardly predicted by empirical approximations. We find that the volume proportion of the BC embedded in coating (F) determines Eabs when the particle to BC core diameter ratio (Dp/Dc) is larger than 2.0. Our findings reveal the potential mechanism behind the differences in observed and modelled Eabs, bulk. The framework builds a bridge connecting the microscopic mixing structure of individual BC particle with Eabs, bulk.

17369. 题目: Biochar-advanced thermocatalytic salvaging of the waste disposable mask with the production of hydrogen and mono-aromatic hydrocarbons
文章编号: N21121505
期刊: Journal of Hazardous Materials
作者: Chenxi Wang, Rongge Zou, Hanwu Lei, Moriko Qian, Xiaona Lin, Wendy Mateo, Lu Wang, Xuesong Zhang, Roger Ruan
更新时间: 2021-12-15
摘要: The salvaging of the waste disposable mask was conducted in this study through catalytic pyrolysis over corn stover derived biochar catalyst combined with the boosted generation of hydrogen and mono-aromatic hydrocarbons for the first time. In the absence of biochar, up to 53wt% of wax was observed at 550 ºC, whereas at the biochar/mask ratio of 2, around 41wt% of liquid oil was produced without the formation of wax. The hydrogen content in the gas stream was about 26vol% at 600 ºC for non-catalytic pyrolysis, which increased to around 55vol% at the expense of light hydrocarbons such as methane and C2-4 for the catalytic process with the biochar/mask ratio of 3. In resulting liquid oil, the content of mono-aromatics, especially toluene, xylenes, and ethylbenzene was about 55% for catalytic runs, which was far greater than that of 38% from the non-catalytic run. Interestingly, the dyes released from mask pyrolysis could be completely captured/adsorbed by biochar, leading to a much cleaner oil. After 10 cycles of reuse at 600 ºC without regeneration, the biochar still held a good selectivity toward hydrogen and mono-aromatic hydrocarbons. This study exemplified a readily accessible concept and pathway of ‘waste against waste’ targeted to upcycle waste disposable masks over biochar from biomass waste.

17370. 题目: Microbial Necromass in Soils—Linking Microbes to Soil Processes and Carbon Turnover
文章编号: N21121504
期刊: Frontiers in Environmental Science
作者: M. Kästner, A. Miltner, S. Thiele-Bruhn, C. Liang
更新时间: 2021-12-15
摘要: The organic matter of living plants is the precursor material of the organic matter stored in terrestrial soil ecosystems. Although a great deal of knowledge exists on the carbon turnover processes of plant material, some of the processes of soil organic matter (SOM) formation, in particular from microbial necromass, are still not fully understood. Recent research showed that a larger part of the original plant matter is converted into microbial biomass, while the remaining part in the soil is modified by extracellular enzymes of microbes. At the end of its life, microbial biomass contributes to the microbial molecular imprint of SOM as necromass with specific properties. Next to appropriate environmental conditions, heterotrophic microorganisms require energy-containing substrates with C, H, O, N, S, P, and many other elements for growth, which are provided by the plant material and the nutrients contained in SOM. As easily degradable substrates are often scarce resources in soil, we can hypothesize that microbes optimize their carbon and energy use. Presumably, microorganisms are able to mobilize biomass building blocks (mono and oligomers of fatty acids, amino acids, amino sugars, nucleotides) with the appropriate stoichiometry from microbial necromass in SOM. This is in contrast to mobilizing only nutrients and consuming energy for new synthesis from primary metabolites of the tricarboxylic acid cycle after complete degradation of the substrates. Microbial necromass is thus an important resource in SOM, and microbial mining of building blocks could be a life strategy contributing to priming effects and providing the resources for new microbial growth cycles. Due to the energy needs of microorganisms, we can conclude that the formation of SOM through microbial biomass depends on energy flux. However, specific details and the variability of microbial growth, carbon use and decay cycles in the soil are not yet fully understood and linked to other fields of soil science. Here, we summarize the current knowledge on microbial energy gain, carbon use, growth, decay, and necromass formation for relevant soil processes, e. g. the microbial carbon pump, C storage, and stabilization. We highlight the factors controlling microbial necromass contribution to SOM and the implications for soil carbon use efficiency (CUE) and we identify research needs for process-based SOM turnover modelling and for understanding the variability of these processes in various soil types under different climates.

17371. 题目: Recent weathering promotes C storage inside large phyllosilicate particles in forest soil
文章编号: N21121503
期刊: Geochimica et Cosmochimica Acta
作者: Ingride Van Der Kellen, Delphine Derrien, Jaafar Ghanbaja, Marie-Pierre Turpault
更新时间: 2021-12-15
摘要: Mineral weathering in soils is expected to promote chemical and physical interactions between soil organic matter and mineral phases, which are known to enhance the protection of organic matter from decomposition. The investigation of mineral-organic associations (MOAs) formation during weathering is therefore crucial to understanding carbon storage processes in soils. Until now studies have been mainly conducted by building inferences from soil characteristics, through short-term laboratory experiments in simplified conditions, or over very long-term time scales using soil chronosequences. Weathering can significantly alter the mineral matrix at the annual timescale, but knowledge regarding MOA formation processes occurring in situ, over short time scales and during the first stage of mineral weathering is lacking. To fill this gap, we performed a mesh bag incubation containing large Na-saturated and organic carbon-free vermiculite particles (200-400 µm in size) in acidic soil of a Douglas-fir forest, in the Beaujolais area (France). The vermiculite bags were deposited at the interface between the forest floor and the mineral soil, where intense weathering occurs. After 20 years of soil incubation, the weathered vermiculite particles were collected and characterized at the macroscale (X ray diffraction and physicochemical analyses), at the microscale (scanning electron microscopy-SEM imaging and element mapping) and at the nanoscale (transmission electron microscopy-TEM imaging, element mapping and speciation by electron energy loss spectroscopy-EELS) on a focus ion beam (FIB) section exposing the inside section of vermiculite particles. Cation exchange capacity, exchangeable cations and elemental analysis of the vermiculite particles showed important changes after 20 years of incubation. The initial exchangeable Na pool was completely depleted. The cation exchange capacity strongly decreased from 178.1 cmolc kg-1 to 49.2 cmolc kg-1 due to interlayer hydroxylation of the weathered vermiculite. The weathering budget indicated a 10% vermiculite dissolution and an organic carbon (C) enrichment of 5 mg g-1. Microscope images and elemental mapping of control vermiculite particles (nonincubated) showed a flat, smooth surface morphology with no detected C. In contrast, 20-year weathered vermiculite particles showed irregular outer- and inner-surfaces marked by multiple cracks from chemical dissolution. Some nano- and microscale exfoliation spaces filled with C were observed inside the weathered particles. C in association with Ca occurred in nanoscale exfoliation spaces. C also occurred entrapped in nanocrystalline Mn oxides (hausmannite) or K-rich aluminosilicates, which precipitated in micro-sized exfoliation spaces. These observations indicated that C storage inside the altered vermiculite particles was both mediated by chemical binding and physical entrapment. The functional groups of the organic matter revealed by EELS spectroscopy strongly differed between nano- and microscale exfoliation spaces. This study using the mineral bag incubation method provides evidence of new processes driving C storage inside large phyllosilicate particles during their initial and recent weathering, which could contribute to long-term C stabilization.

17372. 题目: Contrasting multiple deterministic interpolation responses to different spatial scale in prediction soil organic carbon: A case study in Mollisols regions
文章编号: N21121502
期刊: Ecological Indicators
作者: Baizhi Jiang, Wenyue Xu, Di Zhang, Fan Nie, Qi Sun
更新时间: 2021-12-15
摘要: Accurate estimation of SOM content of Mollisols influences fundamental sub-micron to global-scale biogeochemical processes and carbon-climate feedbacks. Comparative analysis of the responses of Multiple deterministic Interpolation models to spatial scale variations is the basis for multiscale soil organic carbon (SOC) pools simulation and evaluation. This study mainly manifested as spatial variation at different analytical levels of spatial correlation and the change of characteristic data attributes that characterize this change. Three spatial scales were selected (HQ, endemic area; XF, local area; JX, most area). A set of 164 topsoils (0–20 cm, sampling density of 0.1 points / km2) samples were taken, and 14 environmental variables and 14 soil characters variables were employed to contrast prediction accuracy of ordinary kriging (OK), inverse distance weighting (IDW), radial basis function (RBF), global polynomial (GPI), local polynomial (LPI), regression kriging interpolation methods such as (RK) and geographically weighted regression kriging (GWRK) responses to different spatial scale. Using a cross-validation procedure to evaluate the performance of the models. Overall, RK and GWRK, due to the introduction of the auxiliary variables, effectively predict SOM content and the improvement of prediction accuracy depends on the spatial scale, compared with IDW, RBF, GPI, and LPI. Furthermore, soil characters variables (TN, pH) as covariates have a more significant impact on the final prediction than environmental variables (Elevation, Slope, etc.). Therefore, the mutations and trends associated with the spatial resolution are analyzed in different spaces. The root means square error (RMSE) of RK and GWRK are reduced by 46.66 % and 64.26 % compared with OK. RK with fixed the regression coefficient obtained by OLS reveals that the uniformity of the object distribution in HQ and XF have Adjusted R2 0.955 and 0.915. Otherwise, the RI of GWRK with 0.792 adjusted R2 in JX is relatively 17.6 % higher than RK. The results from our case study highlight a key role in selecting the optimal spatial interpolation method for a given dataset associated with spatial scales and analyzing their regularity and applicability on different spatial scales.

17373. 题目: Characterization of the vertical size distribution, composition and chemical properties of dissolved organic matter in the (ultra)oligotrophic Pacific Ocean through a multi-detection approach
文章编号: N21121501
期刊: Marine Chemistry
作者: P. Fourrier, G. Dulaquais, C. Guigue, P. Giamarchi, G. Sarthou, H. Whitby, R. Riso
更新时间: 2021-12-15
摘要: This work presents a multi-analytical approach for the characterization of marine dissolved organic matter (DOM). The determination of marine dissolved organic carbon (DOC) was performed by size exclusion chromatography (SEC) and validated using a certified reference material (CRM) as well as through an intercomparison exercise. Multi-detection SEC, fluorescence and electrochemical methods were used in order to describe the size distribution spectra, the composition and chemical properties of marine DOM, in the (ultra)oligotrophic West Tropical South Pacific Ocean (WTSP). In this work, we defined the state of degradation of DOC in the different size fractions, operationally defined by SEC. We estimated that on average 62% of DOC was of humic nature (0.5–10 kDa), of which ~9% was able to complex trace elements, such as iron (Fe). Our results tend to support that non-refractory DOC is of high molecular weight (HMW), nitrogen (N)-rich, aliphatic, and has a weak fluorescence quantum yield and an enhanced binding capacity for Fe. The ageing of marine DOM occurring within mesopelagic waters is mainly driven by microbial respiration and alters these chemical properties. Although our results are in agreement with a paradigm describing oceanic DOM biogeochemistry known as the size-reactivity continuum, 3 μmolC L−1 of very HMW (> 10 kDa) were still observed in a water mass mainly composed of Pacific Deep Waters. This persistence could be explained by a significant content (5%) of aromatic carbon that may protect HMW DOM from long term biodegradation.

17374. 题目: Insight into the organic matter degradation enhancement in the bioelectrochemically-assisted sludge treatment wetland: Transformation of the organic matter and microbial community evolution
文章编号: N21121409
期刊: Chemosphere
作者: Shutian Wang, Qingliang Zhao, Junqiu Jiang, Kun Wang
更新时间: 2021-12-14
摘要: Sludge treatment wetland (STW) has been widely used to dewater and mineralize the various sludge, but the low degradation ability of organic matter can limit its application. Bioelectrochemistry has been proven to accelerate the degradation of organic compounds and recover bioenergy from the sludge. In this study, a bioelectrochemical-assisted sludge treatment wetland (BE-STW) system was constructed to determine the most common types of degraded organic matter and the functional bacterial community. It was found that the bioelectrochemistry process contributed to a further removal of the total chemical oxygen demand (TCOD) by 19% (±0.6) and the additional soluble chemical oxygen demand (SCOD) value was 64.10% (±0.63), with a voltage output of 0.961 V and a power density of 0.351 W/m3. The hydrophilic and hydrophobic acid fractions of the sludge were preferentially removed in BE-STW. The tryptophan-like protein and fulvic acid-like substances were totally removed, whereas, the hydrolysis of aromatic organic compounds in the neutral and hydrophobic acid fractions was enhanced. Also, the enrichment of Longilinea and Methylophilus improved the hydrolysis of organic matter. Moreover, the high relative abundance of Thauera, Dechloromonas, and Syntrophorhabdus could accelerate the degradation of aromatic compounds in the BE-STW system. The bacteria from the genus Geobacter was predominantly detected (2.48%) in the anodic biofilm on BE-STW. The results showed that bioelectrochemistry could improve the sludge stabilization degree in STW, accelerate the organic matter degradation and hydrolysis efficiency, and harvest bioelectricity, simultaneously. This technology can provide a new pathway to increase the efficiency of the traditional STW systems.

17375. 题目: Oxidative degradation of commingled trichloroethylene and 1,4-dioxane by hydroxyl radicals produced upon oxygenation of a reduced clay mineral
文章编号: N21121408
期刊: Chemosphere
作者: Ziqi Zhou, Qiang Zeng, Gaoyuan Li, Dafu Hu, Qingyin Xia, Hailiang Dong
更新时间: 2021-12-14
摘要: Improper disposal of chlorinated solvents such as trichloroethylene (TCE) and its stabilizer 1,4-dioxane has resulted in extensive contamination in soils and groundwater. Oxidative degradation of these contaminants by strong oxidants has been proposed recently as a remediation strategy, but specific mechanisms and degradation efficiencies are still poorly understood, especially in commingled systems. In this study, a reduced iron-bearing clay (RIC), nontronite (rNAu-2), was oxygenated to produce hydroxyl radicals (•OH) for degradation of TCE and 1,4-dioxane under circumneutral and dark conditions. Results showed that TCE and 1,4-dioxane could be effectively degraded during oxygenation of rNAu-2 in both single and commingled systems. Compared with the single compound system, the degradation rates and efficiencies of TCE and 1,4-dioxane decreased in the commingled system. The negative effect was more significant for TCE than 1,4-dioxane. The commingled TCE and 1,4-dioxane impacted the degradation pattern of each other, due to their difference in •OH scavenging efficiency, surface affinity to rNAu-2 and solubility. Moreover, solution pH, buffer type, rNAu-2 dosage, and dissolved organic matter all affected •OH production and contaminant degradation efficiency. Our findings provide new insights for investigating the natural attenuation of commingled chlorinated solvents and 1,4-dioxane by RIC in redox-fluctuating environments and offer guidance for developing possible in-situ remediation strategies.

17376. 题目: Mineral and climatic controls over soil organic matter stability across the Tibetan alpine permafrost region
文章编号: N21121407
期刊: Global Biogeochemical Cycles
作者: Kai Fang, Leiyi Chen, Shuqi Qin, Qiwen Zhang, Xuning Liu, Pengdong Chen, Yuanhe Yang
更新时间: 2021-12-14
摘要: Permafrost thaw could accelerate microbial decomposition, lead to greenhouse gases emissions into the atmosphere, and thus trigger a positive feedback to climate warming. As a key parameter reflecting the resistance of soil organic matter (SOM) to be decomposed by microorganisms, SOM stability may determine the strength of permafrost carbon (C)-climate feedback. Adequate understanding of patterns and drivers of SOM stability can thus contribute to predict permafrost C cycle and its feedback to climate change. However, due to limited observations, it remains unknown whether biochemical selectivity or physico-chemical protection dominates SOM stability in permafrost regions. By combining large-scale soil sampling, thermal analysis and random forest model, we quantified SOM stability in the top 10 cm using thermogravimetry (TG) and differential scanning calorimetry (DSC), and explored its spatial patterns across the Tibetan alpine permafrost region. We then constructed structural equation model (SEM) to evaluate the relative importance of climatic variables, edaphic properties, substrate quality, and mineral variables in regulating SOM stability over a broad geographic scale. Our results indicated that SOM stability exhibited an increasing tendency from the southeastern to northwestern plateau. The stronger SOM stability was associated with higher mineral-organic associations and more arid conditions. By contrast, substrate quality had limited effects on SOM stability. Overall, these results provide large-scale evidence for the physico-chemical protection hypothesis, highlighting the importance of considering mineral variables in Earth System Models to better predict soil C dynamics across permafrost regions.

17377. 题目: Seasonal dynamics of chromophoric dissolved organic matter in Poyang Lake, the largest freshwater lake in China
文章编号: N21121406
期刊: Journal of Hydrology
作者: Qi Huang, Lizhen Liu, Jiacong Huang, Dianwei Chi
更新时间: 2021-12-14
摘要: Chromophoric dissolved organic matter (CDOM) plays a vital role in the biogeochemical cycles of elements in aquatic ecosystems. Seasonal dynamics of CDOM of the lake are sensitive indicators of the biogeochemical processes and water quality, which are critical to the water security of the lake. Thus, a field investigation of the CDOM and dissolved organic carbon (DOC) properties was conducted during four hydrological seasons in 2016 to track the temporal variability of CDOM and DOC properties and to explore the influence of rivers and wetlands on the quantity and quality of CDOM in Poyang Lake. The results showed that the alternations of flood and dry periods have a different influence on the quantity and quality of CDOM and DOC in the main lake and the river mouths districts. DOC and aromaticity in the main lake district were more influenced by seasonal variations, while CDOM concentrations and molecular weight in the river mouths were more affected. CDOM fluorescent components in both these districts varied obviously across the hydrological seasons. More terrestrial humic-like substances with higher aromaticity and lower DOC in the rising and flood season than in the dry and retreating season. The contributing rate of CDOM and its terrestrial humic-like substances from input rivers to the lake in the rising season can account for more than 50%, which was more than that in the flood season. Flooding causes wetlands to contribute a higher abundance of CDOM and DOC with lower aromaticity to the lake, contrary to the CDOM features in the flood season, highlighting the important role of wetlands in the organic carbon pool. The DOC can be modeled using CDOM fluorescent and optical parameters by the Support Vector Regression (SVR) method, which provides a tool for DOC dynamic monitoring and water quality management.

17378. 题目: Cornstalk biochar promoted the denitrification performance and cellulose degradation rate of Burkholderia sp. CF6
文章编号: N21121405
期刊: Journal of Environmental Chemical Engineering
作者: Changlun Chen, Junfeng Su, Amjad Ali, Zhenyu Zhai
更新时间: 2021-12-14
摘要: A strain Burkholderia sp. CF6 with denitrification and cellulose degradation ability was isolated. When sodium carboxymethyl cellulose (CMC-Na) dosage was 5gL-1, the nitrate removal efficiency reached 96.48% after 48h and the nitrite accumulation was only 0.07mgL-1. The exponential decay equation was used to match the kinetics of denitrification and the correlation coefficient (R2) was higher than 0.940. The denitrification and cellulose degradation capabilities were promoted by cornstalk biochar. Through the comparison of nitrogen balance of different biochars, biochar of 400 ℃ (BC400) had the highest gaseous nitrogen conversion efficiency (83.31%). BC400 can accelerate the nitrate removal rate (from 0.08 to 0.32mgL-1 h-1) and shorten the peak time of cellulase activity (from 48 to 24h). The fourier transform infrared spectroscopy (FTIR) manifested that the BC400 assisted biological denitrification was achieved through phenolic and quinone groups. From the results of three-dimensional excitation-emission matrix (3D-EEM), it can be concluded that soluble microbial by-product and aromatic protein have a significant correlation with the effect of BC400 on the biological process of strain CF6. This research will provide new insights for agricultural waste utilization to treat low carbon to nitrogen (C/N) ratio wastewater.

17379. 题目: Adsorption of benzalkonium chlorides onto polyethylene microplastics: Mechanism and toxicity evaluation
文章编号: N21121404
期刊: Journal of Hazardous Materials
作者: Tae-Kyoung Kim, Minhee Jang, Yu Sik Hwang
更新时间: 2021-12-14
摘要: Usage of disposable plastic products and disinfectants has been skyrocketing due to the COVID-19 pandemic. The random disposal of plastic products may result in greater microplastic pollution. Benzalkonium chloride is known as one of the most common ingredients of disinfectants. In this study, the adsorption behavior of benzalkonium chlorides (BAC12, BAC14, BAC16) on polyethylene microplastics (PE-MPs) and the combined toxic effects were investigated using batch adsorption experiment and Daphnia magna. The results showed that PE-MPs had strong adsorption capacity for BACs and the adsorption capacity increased (11.03 to 22.77mg/g) with their octanol-water distribution coefficients. The effect of pH was negligible while dissolved organic matter inhibited the adsorption. A slightly inverse relationship between particle size of PE-MPs and adsorption was observed. Additionally, the MP aging with UV/H2O2 increased the adsorption of BAC12 but decreased that of relatively hydrophobic BAC14 and BAC16. The survival rate of Daphnia magna increased up to 100% in the presence of PE-MPs depending upon their adsorption capacities, suggesting that PE-MPs do not act as a carrier but rather as a scavenger for BACs. This study provides important information necessary for environmental risk assessment with regard to the combined pollution of MPs and toxic chemicals.

17380. 题目: Carbonaceous aerosols and their light absorption properties over the Bay of Bengal during continental outflow
文章编号: N21121403
期刊: Environmental Science: Processes & Impacts
作者: Gourav Nayak, Ashwini Kumar, Srinivas Bikkina, Shani Tiwari, Suhas S. Sheteye, A. K. Sudheer
更新时间: 2021-12-14
摘要: The marine atmosphere of the Bay of Bengal (BoB) is prone to get impacted by anthropogenic aerosols from the Indo-Gangetic Plain (IGP) and Southeast Asia (SEA), particularly during the northeast monsoon (NEM). In this study, we quantify and characterize carbonaceous aerosols and their absorption properties collected in two cruise campaigns onboard ORV Sindhu Sadhana during the continental outflow period over the BoB. Aerosol samples were classified based on the air mass back trajectory analyses, wherein samples were impacted by the continental air parcel (CAP), marine air parcel (MAP), and mix of both (CAP + MAP). Significant variability in the PM10 mass concentration (in μg m−3) is found with a maximum value for MAP samples (75.5 ± 36.4) followed by CAP + MAP (58.5 ± 27.3) and CAP (58.5 ± 27.3). The OC/EC ratio (>2) and diagnostic tracers i.e. nss-K+/EC (0.2–0.96) and nss-K+/OC (0.11–1.32) along with the absorption angstrom exponent (AAE: 4.31–6.02) and MODIS (Moderate Resolution Imaging Spectroradiometer) derived fire counts suggest the dominance of biomass burning emission sources. A positive correlation between OC and EC (i.e. r = 0.86, 0.70, and 0.42 for CAP, MAP, and CAP + MAP, respectively) further confirmed the similar emission sources of carbonaceous species. Similarly, a significant correlation between estimated secondary organic carbon (SOC) and water-soluble organic carbon (WSOC; r = 0.99, 0.96, and 0.97 for CAP, MAP, and CAP + MAP, respectively) indicate their similar chemical nature as well as dominant contribution of SOC to WSOC. The absorption coefficient (babs-365) and mass absorption efficiency (MAEBrC-365) of the soluble fraction were estimated at 365 nm wherein, babs-365 showed a linear relationship with WSOC and nss-K+, signifying the contribution of water soluble brown carbon from biomass burning emissions. The estimated MAEBrC-365 (0.30–0.93 m2 g−1), during this study, was consistent with the earlier observations over the BoB, particularly during the continental outflow season.