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17681. 题目: Soil organic carbon estimation using VNIR–SWIR spectroscopy: The effect of multiple sensors and scanning conditions
文章编号: N21042909
期刊: Soil and Tillage Research
作者: Asa Gholizadeh, Carsten Neumann, Sabine Chabrillat, Bas van Wesemael, Fabio Castaldi, Luboš Borůvka, Jonathan Sanderman, Aleš Klement, Christian Hohmann
更新时间: 2021-04-29
摘要: Visible–near infrared–shortwave infrared (VNIR–SWIR) spectroscopy is being increasingly used for soil organic carbon (SOC) assessment. Common practice consists of scanning soil samples using a single spectrometer. Considerations have rarely been documented of the effects of using multiple instruments and scanning conditions on SOC model calibration that occur when merging soil spectral libraries (SSLs), particularly in soils with low SOC concentration and using both field spectroradiometers and laboratory fixed spectrometers. To address this gap, we scanned 143 low-SOC-content soil samples using three spectrometers (ASD FieldSpec 3, ASD FieldSpec 4, and FOSS XDS) and four setup features - FOSS, contact probe (CP), dark-box (DB), and open laboratory (LAB) - at three laboratories. The application of an internal soil standard (ISS) to align one laboratory spectrum with another for spectral correction and spectral merging of various SSLs was examined. SOC models were developed using i) data from each single spectrometer – single laboratory separately and ii) merged data from multiple spectrometers – different laboratories, applying the 1st derivatives of spectra and random forest (RF) regression. The results indicate that the spectral shape and wavelength position of key features obtained from all spectrometers and setups did not show any noticeable differences, though spectra based on FOSS setup, particularly on low-SOC samples, demonstrated greater range in absolute derivative values regardless of ISS application. The derivative ISS-corrected spectra showed less variation among different spectrometers compared to their uncorrected raw reflectance spectra. All single spectrometer models predicted SOC reasonably well. However, the spectra acquired by the FOSS setup predicted SOC more accurately (R2 = 0.77, RPIQ = 3.30, RMSE = 0.22 %, and SD = 0.04) than the spectra acquired by the other setups. The models derived from merged uncorrected raw reflectance spectra yielded poor results (R2 = 0.48, RPIQ = 2.33, RMSE = 0.33 %, and SD = 0.10); nevertheless, assessment of SOC using the 1st derivative ISS-corrected merged SSLs considerably improved the prediction accuracy (R2 = 0.70, RPIQ = 3.10, RMSE = 0.25 %, and SD = 0.06). Hence, the derivative spectra coupled with the ISS correction improved the accuracy of SOC prediction models obtained from the merged soil spectra collected in different environments using different instruments. We therefore recommend application of the ISS spectral alignment method linked to the 1st derivative approach to enhance the compilation of SSLs at the regional and global scales for SOC assessment.

17682. 题目: Effects of land use types and environmental factors on spatial distribution of soil total nitrogen in a coalfield on the Loess Plateau, China
文章编号: N21042908
期刊: Soil and Tillage Research
作者: Ziguan Wang, Guangcai Wang, Guanghui Zhang, Haibo Wang, Tingyu Ren
更新时间: 2021-04-29
摘要: Soil total nitrogen (TN) is one of the most important nutrients for plant and crop growth. It is essential to estimate the spatial distribution of TN to evaluate soil productivity, land reclamation efficiency, and agricultural management. This study was performed to investigate the spatial distribution of TN and its influencing factors in a coalfield in the Loess Plateau, China. A total of 143 topsoil samples were collected from five land use types and different slope positions. Classical statistical and geostatistical methods were used to quantify the spatial variation in TN. Redundancy analysis (RDA) was used to detect correlations between environmental factors and TN, whereas the random forest (RF) algorithm and LightGBM were applied to simulate the correlations. The results showed that the degree of spatial dependence ranged from 31.7%–45.2%, indicating moderate spatial variability in TN. Land use type significantly affected TN. The highest TN contents were found in the conservation tillage lands, followed by conventional tillage land, shrub land, grassland, and coal mining areas. The spatial distribution of the TN was also influenced by the slope position. The sites located downslope had higher TN than those located on the upper and middle slopes. RDA indicated that available potassium (AK) and soil organic matter (SOM) significantly affected the spatial distribution of TN. It was also demonstrated by LightGBM and RF that the TN content could be simulated by AK, SOM, normalised vegetation index, elevation, and available phosphorus. These results are helpful in understanding the effects of anthropogenic and natural factors on soil TN in coalfield areas.

17683. 题目: A novel submerged photocatalytic oscillatory membrane reactor for water polishing
文章编号: N21042907
期刊: Journal of Environmental Chemical Engineering
作者: Siddharth Gupta, Hassan Gomaa, Madhumita B. Ray
更新时间: 2021-04-29
摘要: A submerged photocatalytic oscillatory membrane reactor was tested for micropollutants removal from water as a tertiary treatment method for water polishing. A detailed study of the system performance at various operating conditions of membrane reactor and background water matrices including humic acid (HA) and secondary wastewater effluent (SWE) was conducted. Initially, the system was evaluated using suspended nanosized TiO2 under UV illumination and antipyrine as a model pollutant. Experiments using central composite design (CCD) and response surface analysis (RSM) were used to analyze the effects of the oscillation amplitude and frequency, and airflow rate on the antipyrine removal and the membrane flux. Optimum conditions for the reactor operation were determined using a composite desirability function. These conditions were then applied for the removal of other micropollutants with varying physiochemical properties namely, diclofenac, sulfamethoxazole, and hydrochlorothiazide. Up to 90% micropollutants removal can be achieved in Milli-Q water, although, the performance was noticeably affected in presence of background organics in SWE and HA due to either catalyst blocking and/or competition of organics, as well as catalyst agglomeration. A significant process intensification can be achieved using the proposed photocatalytic oscillatory membrane reactor configuration, which could offer a promising potential as a final polishing step for water recycling.

17684. 题目: Functional soil organic matter fraction in response to short-term tillage management under the double-cropping rice paddy field in southern of China
文章编号: N21042906
期刊: Environmental Science and Pollution Research
作者: Haiming Tang, Chao Li, Lihong Shi, Li Wen, Kaikai Cheng, Weiyan Li, Xiaoping Xiao
更新时间: 2021-04-29
摘要: Soil organic matter (SOM) and its fraction play an important role in maintaining and improving soil fertility of paddy field. However, there is still limited information about how SOM fraction response to carbon (C) sequestration with different short-term tillage practices under the double-cropping rice paddy field in southern of China. Therefore, the effects of 5-year short-term tillage treatments on different SOM fractions (physically protected, physico-chemically protected, physico-biochemically protected, chemically protected, biochemically protected, and unprotected) under the double-cropping rice paddy field in southern of China were studied in this paper. The field experiment included four different tillage treatments: rotary tillage with crop residue removed as a control (RTO), conventional tillage with crop residue incorporation (CT), rotary tillage with crop residue incorporation (RT), and no-tillage with crop residue retention (NT). The results showed that soil unprotected (cPOM), biochemically (NH-dSilt), physically-biochemically (NH-μSilt), and chemically protected (H-dSilt) fractions with different tillage treatments were the mainly C storage fraction in paddy field. The soil organic carbon (SOC) content in unprotected (cPOM and fPOM), physically protected (iPOM), and physico-chemically protected (H-μClay) fractions with CT treatment was increased by 1.45, 2.13, 1.91, and 1.42 times higher than that of RTO treatment, respectively. The results showed that largest proportion of fraction to SOC content was biochemically protected, followed by unprotected and physically-biochemically protected, and physically protected was the lowest. These results indicated that soil physically protected, physically-chemically protected, and physically-biochemically protected fractions with CT and RT treatments were higher than that of NT and RTO treatments. In summary, it was a benefit practice for increasing SOM fraction under the double-cropping rice paddy field in southern of China by combined application of conventional tillage and rotary tillage with crop residue incorporation management.

17685. 题目: Electrochemically Modified Adsorbents for Treatment of Aqueous Arsenic: Pore Diffusion in Modified Biomass vs. Biochar
文章编号: N21042905
期刊: Chemical Engineering Journal
作者: Khaled Zoroufchi Benis, Jafar Soltan, Kerry N. McPhedran
更新时间: 2021-04-29
摘要: Canola straw-based biomass and biochar adsorbents were electrochemically modified and used to remove arsenate (As(V)) from water. Studying the effects of the modification parameters on the As(V) adsorption capacity of the modified materials showed that the materials treated at lower pH (3) and drying temperatures (60 °C) had higher As(V) uptake. The modification conditions were optimized to obtain optimum modified biomass (OBM) and biochar (OBC) with the highest As(V) adsorption capacity. Characterization of the OBM and OBC indicated that the deposited iron oxide on the surface of the adsorbents was goethite. The adsorption isotherms and kinetic data suggested that a hybrid adsorption mechanism took place under the experimental conditions with a higher probability of heterogeneous multilayer chemisorption. Solid-phase speciation of the sorbed As(V) indicated a negligible reduction (2.5%) of As(V) to arsenite (As(III)) on OBM, while no reduction occurred on OBC. The liquid film mass transfer coefficient (kf) and effective pore diffusion coefficient (Dp) were estimated using a shrinking core model combined with a genetic algorithm. A higher tortuosity factor of 3.75 for the OBM was obtained as compared to 2.93 for the OBC. Overall, the applied electrochemical modification successfully enhanced the As(V) sorption capacity of both the biomass and biochar from 8 to 766 and 25 to 922 µg/g, respectively, indicating promising potential of this method for preparation of high performance adsorbents.

17686. 题目: Simultaneous adsorption of Cr(VI) and phenol by biochar-based iron oxide composites in water: Performance, kinetics and mechanism
文章编号: N21042904
期刊: Journal of Hazardous Materials
作者: Fu-Xin Dong, Liu Yan, Xin-Hua Zhou, Shi-Ting Huang, Jing-Yi Liang, Wen-Xuan Zhang, Zi-Wei Guo, Peng-Ran Guo, Wei Qian, Ling-Jun Kong, Wei Chu, Zeng-Hui Diao
更新时间: 2021-04-29
摘要: The pollution of heavy metals and organic compounds has received increased attention in recent years. In the current study, a novel biochar-based iron oxide composite (FeYBC) was successfully synthesized using pomelo peel and ferric chloride solution through one-step process at moderate temperature. Results clearly demonstrate that FeYBC exhibited more efficient removal of Cr(VI) and/or phenol compared with the pristine biochar, and the maximum adsorption amounts of Cr(VI) and phenol by FeYBC could reach 24.37 and 39.32mgg-1, respectively. A series of characterization data suggests that several iron oxides such as Fe2O3, Fe0, FeOOH and Fe3O4 were formed on the FeYBC surface as well as oxygen-containing groups. Thermodynamics study indicates that Cr(VI) and phenol adsorption by FeYBC were endothermic and exothermic processes, respectively. Langmuir adsorption isotherm and pseudo-second order models could better explain the Cr(VI) and phenol adsorption behaviors over FeYBC. The Cr(VI) adsorption might be primarily achieved through the ion exchange and surface complexation and reduction, whereas the π-π interaction and electron donor–acceptor complex mainly contributed to phenol adsorption. The findings indicate that the biochar-based iron oxide composites material was an efficient adsorbent for the remediation of industrial effluents containing Cr(VI) and phenol.

17687. 题目: Green additive to upgrade biochar from spent coffee grounds by torrefaction for pollution mitigation
文章编号: N21042903
期刊: Environmental Pollution
作者: Kuan-Ting Lee, Jyun-Ting Du, Wei-Hsin Chen, Aristotle T. Ubando, Keat Teong Lee
更新时间: 2021-04-29
摘要: A green approach using hydrogen peroxide (H2O2) to intensify the fuel properties of spent coffee grounds (SCGs) through torrefaction is developed in this study to minimize environmental pollution. Meanwhile, a neural network (NN) is used to minimize bulk density at different combinations of operating conditions to show the accurate and reliable model of NN (R2=0.9994). The biochar produced from SCGs torrefied at temperatures of 200-300 °C, duration of 30-60 min, and H2O2 concentrations of 0-100 wt% is examined. The results reveal that the higher heating value (HHV) of biochar increases with rising temperature, duration, or H2O2 concentration, whereas the bulk density has an opposite trend. The HHV, ignition temperature, and bulk density of biochar from torrefaction at 230 °C for 30 min with a 100 wt% H2O2 solution (230-100%-TSCG) are 27.00 MJ∙kg-1, 292 °C, and 120 kg∙m-3, respectively. This HHV accounts for a 29% improvement compared to that of untorrefied SCG. The contact angle (126°), water activity (0.51 aw), and moisture content (7.69%) of the optimized biochar indicate that it has higher resistance against biodegradation, and thereby can be stored longer. Overall, H2O2 is a green treatment additive for SCGs solid fuel. This study has successfully produced biochar with greater HHV and low bulk density at low temperatures. The green additive development can effectively reduce environmental pollutants and upgrade wastes into resources, and achieve 3E, namely, environmental (non-polluting green additives), energy (biofuel), and circular economy (waste upgrade). In addition, the produced biochar has great potential in the fields of bioadsorbents and soil amendments.

17688. 题目: Synthesis of zero-valent iron/biochar by carbothermal reduction from wood waste and iron mud for removing rhodamine B
文章编号: N21042902
期刊: Environmental Science and Pollution Research
作者: Chao Chen, Jianguo Liu, Chao Gen, Qin Liu, Xuetao Zhu, Wenzhi Qi, Fan Wang
更新时间: 2021-04-29
摘要: This study proposes a new process to synthesize zero-valent iron/biochar (Fe0-BC) by carbothermal reduction using wood waste and iron mud as raw materials under different temperature. The characterization results showed that the Fe0-BC synthesized at 1200 °C (Fe0-BC-1200) possessed favorable adsorption capacity with the specific surface area of 103.18 m2/g and that the zero-valent iron (Fe0) particles were uniformly dispersed on the biochar surface. The removal efficiency of rhodamine B (RB) was determined to evaluate the performance of the prepared Fe0-BC. Fe0-BC-1200 presented the best performance on RB removal, which mainly ascribes to that more Fe0 particles generated at higher temperature. The equilibrium adsorption capacity reached 49.93 mg/g when the initial RB concentration and the Fe0-BC-1200 dosage were 100 mg/L and 2 g/L, respectively, and the pseudo-second-order model was suitable to fit the removal experimental data. LCMC and XRD analyses revealed that the removal mechanism included the physical adsorption of biochar and the redox reaction of Fe0. Moreover, copper existing in the iron mud was also reduced to Cu0, which was beneficial to catalyze the oxidation of iron; the degradation of RB was promoted at the same time.

17689. 题目: Strong adsorption of metolachlor by biochar prepared from walnut shells in water
文章编号: N21042901
期刊: Environmental Science and Pollution Research
作者: Lu Liu, Yingjie Dai
更新时间: 2021-04-29
摘要: In this study, we investigated the removal of metolachlor (MET) by biochar (BC) prepared from walnut shells (W-BC) compared with BCs made from cow dung (D-BC) and corn cobs (C-BC) by characterizing the adsorption kinetics, pH, adsorbent dose, and ionic strength, and using isotherm models. Weight analysis was also conducted to understand the adsorption capacity and adsorption mechanisms. The results showed that the MET removal rates were 87.89% (W-BC), 52.91% (D-BC), and 10.91% (C-BC), respectively. According to the results fitted to the Langmuir isotherm model, the saturated adsorption capacities for MET were 96.15 mg g−1, 37.88 mg g−1, and 11.98 mg g−1 with W-BC, D-BC, and C-BC, respectively. The results demonstrated that W-BC was particularly effective at MET removal. Analyses based on the weights of different factors showed that the correlation coefficient was highest for the BC type with 46.11% in the MET adsorption process, followed by the initial concentration of MET (19.29%). The adsorption of MET by BCs was probably influenced mostly by electron donor–acceptor interactions and pore filling. These results may facilitate further studies of the adsorption mechanism and optimization of the process.

17690. 题目: Improving the degradation of benzo[a]pyrene and soil biodegradability by enhanced ozonation with mechanical agitation
文章编号: N21042815
期刊: Chemical Engineering Journal
作者: Xi Li, Ting Luo, Yaxuan Wang, Bing Wang, Hong Liang, Jiabin Zhou, Lingli Li
更新时间: 2021-04-28
摘要: Gas-phase ozone (O3) can easily diffuse into soil aggregates and effectively degrade hydrocarbon compounds. However, gas channels in soil impede remediation efficiency. This study developed an enhanced ozonation by applying mechanical agitation (100 and 150 rpm) compared with conventional ozonation (0 rpm), to improve degradation of benzo[a]pyrene (BaP) and soil biodegradability. During ozonation process, O3 consumption, BaP removal, soil carbon balance, and intermediates of BaP were investigated. Results showed that the enhanced ozonation disturbed gas channels and improved utilization of O3. At 90 min, more than 90% of the initial BaP (67.86 mg/kg) was degraded at 100 rpm, while it was 83.61% at conventional ozonation. Enhanced ozonation rapidly oxidized soil organic carbon (SOC), Acetone-n-hexane-extractable organic carbon (AeOC), residual organic carbon (ROC) and BaP into dissolved organic carbon (DOC), which increase of DOC was 31.97% higher than conventional ozonation. Enhanced ozonation accelerated decomposition of BaP to more biodegradable and lower molecular weight intermediates at short time mainly by increasing direct ozonation, which was conducive to the subsequent biodegradation. This work provides an enhanced ozonation to improve the degradation efficiency of BaP in soil by destroying gas channels and enhancing the utilization efficiency of O3 and direct ozonation.

17691. 题目: Fate of plastic film residues in agro-ecosystem and its effects on aggregate-associated soil carbon and nitrogen stocks
文章编号: N21042814
期刊: Journal of Hazardous Materials
作者: Ze-Ying Zhao, Peng-Yang Wang, Yi-Bo Wang, Rui Zhou, Kiprotich Koskei, Alex Ndolo Munyasya, Shu-Tong Liu, Wei Wang, Yong-Zhong Su, You-Cai Xiong
更新时间: 2021-04-28
摘要: Biodegradable (Bio) plastic films are widely viewed as promising alternative products of low-density polyethylene (LDPE) films to minimize plastic debris accumulation and pollution in agroecosystems. Yet, this speculation indeed lacks of sufficient evidences. We conducted a landfill investigation on the aging characteristics of Bio and LDPE plastic films in maize field, and the effects on soil aggregate composition and carbon & nitrogen stocks. The degradation rate of Bio film was up to 41.1% while that of LDPE film was zero. Scanning electron microscope (SEM) showed that the crack formation of Bio film had a pronounced domino effect, and FTIR showed that old Bio film displayed an extra wide peak threshold ranging from 3000 to 3500cm-1. Particularly, the abundance of microplastics was elevated with the increased plastic residues, and the increment mostly resulted from Bio residues. Critically, plastic residues significantly lowered the soil macro-aggregates (>0.25mm) proportion, while increasing that of micro-aggregates (0.1-0.25mm) in LDPE, and silt/clay fraction (<0.1mm) in Bio respectively. They significantly promoted total nitrogen content of the aggregates with the same size, but decreased the organic carbon content, dramatically lowering the C/N. Therefore, we first identified the fate of plastic film residues in agroecosystems and revealed the serious deficiencies of Bio plastic film.

17692. 题目: Performance and stratified microbial community of vermi-filter affected by Acorus calamus and Epipremnum aureum during recycling of concentrated excess sludge
文章编号: N21042813
期刊: Chemosphere
作者: Kui Huang, Chunlei Sang, Mengxin Guan, Ying Wu, Hui Xia, Yongzhi Chen, Cailong Nie
更新时间: 2021-04-28
摘要: Vermi-filter combined with wetland plant (VFP) is an eco-friendly and sustainable approach for recycling of excess sludge by joint action of earthworms, wetland plants and microorganisms. However, the effects of wetland plants on sludge decomposition and involved microorganisms are remain unclear. This study investigated the effects of wetland plants on the treatment performance of VFP for concentrated excess sludge and microbial community distribution inside the VFP. The wetland plants’ species of Acorus calamus and Epipremnum aureum were separately planted on the surface layer of vermi-reactors by earthworms Eisenia fetida. Results showed that the growth rate of E. fetida in VFPs significantly (P<0.001) increased by 75%, compared to VF. In addition, the removal rates of total solids and chemical oxygen demand in VFPs could reach 61%-79% and 36%-68%, respectively, displaying a better performance of sludge reduction than in the VF. The surface layer of VFPs was a hotspot for degradation of organic matter, where bacteria played an important role in bio-decomposition rather than eukaryotes. Moreover, wetland plants could significantly (P<0.001) enrich the eukaryotic population, rather than bacterial population. Compared to the VF, the wetland plants could promote the diversities of bacterial community in VFPs, showing specific functioned genus in different layers. In contrast, A. calamus could be a better candidate than E. aureum in the VFP. This study suggests that the inoculation of wetland plants can improve the performance for treating concentrated excess sludge by changing the biomass of earthworms and the structure of microbial community within the VFP.

17693. 题目: UVC-induced degradation of cilastatin in natural water and treated wastewater
文章编号: N21042812
期刊: Chemosphere
作者: Nicoleta Solomou, Marco Minella, Davide Vione, Elefteria Psillakis
更新时间: 2021-04-28
摘要: This work reports for the first time the UVC photodegradation of cilastatin, a renal dehydropeptidase inhibitor co-adminstered with the imipenem antibiotic. Initially, solutions of cilastatin at varying concentrations were prepared in ultra-pure water and the direct photolysis of cilastatin was monitored under 254-nm irradiation. Degradation was slower at higher initial cilastatin concentrations, due to absorption saturation. Of the different eluting photoproducts, only one was tentatively identified as oxidized cilastatin bearing a sulfoxide group. UV-254 photolysis occurred faster at lower pH values, because the protonated forms of the molecule (H3A+, H2A) have both higher absorption coefficients and higher photolysis quantum yields than the non-protonated ones (HA−, A2−). The direct photolysis of cilastatin does not involve •OH, as excluded by experiments in which t-butanol was added as •OH scavenger, whereas the presence of humic acids inhibited photolysis due to competition for radiation absorption. The same explanation partially accounts for the observation that the photolysis kinetics of cilastatin was slower in tap water, river water and treated wastewater samples compared to ultra-pure water. Moreover, the direct photolysis quantum yield was also lower in water matrices compared to ultra-pure water. Similar findings reported for triclosan and the herbicide 2-methyl-4-chlorophenoxyacetic acid in previous studies might suggest that the water matrix components could carry out either physical quenching of cilastatin’s excited states or back-reduction to cilastatin of the partially oxidized degradation intermediates. Overall, the present results demonstrate that UVC irradiation is a fast and efficient process for the degradation of cilastatin in natural water and wastewater.

17694. 题目: The effect of tillage management on microbial functions in a maize crop at different slope positions
文章编号: N21042811
期刊: Geoderma
作者: Meng Xu, Laura M. Cardenas, Claire Horrocks, María López-Aizpún, Junling Zhang, Fusuo Zhang, Jennifer A.J. Dungait
更新时间: 2021-04-28
摘要: Determining whether agricultural soils act as sinks or sources of greenhouse gases (GHGs) requires the quantification of variations in the pools and fluxes of soil organic carbon (SOC) and nutrients, e.g. nitrogen (N), as well as the associated soil microbial responses. In this study, soil was collected from experimental plots of maize (Zea mays) under conventional, minimum or strip tillage treatments established in a sloping field (~10%) of loamy soil in SW England, UK, where maize had been cultivated conventionally for 12 years. Topsoil (0–10 cm) cores were collected from the top, mid, bottom and foot slope positions to investigate soil C, N and microbial properties. The impact of conventional management on potential GHG emissions was assessed by incubating soils collected from the top, mid and bottom slope positions from the conventional treatment. Contents of SOC and total N were greatest at the top slope position and soil mineral N (NO3−-N and NH4+-N) concentrations were greater at the bottom and foot slope positions in all treatments. Biomarker phospholipid fatty acids (PLFA) for Gram positive bacteria and fungi were relatively 13C-enriched at each slope position regardless of treatment, indicating preferential utilization of organic matter from maize (C4) rather than SOC (C3). Around 70% of carbon incorporated into total PLFA was derived from C3-SOC at the slope foot, indicating that more SOC older than 12 years was being mineralized at the depositional position. Effluxes of N2O and CO2, and total GHG emission were greatest from the incubated soils sampled from the bottom slope position, suggesting that conditions in depositional positions of regularly ploughed sloping arable fields may have increased the potential for mineralization and denitrification. We conclude that the C sink potential of the depositional positions of slopes may be diminished by coincidental GHG emissions.

17695. 题目: Spatial characteristics and removal of dissolved black carbon in the western Arctic Ocean and Bering Sea
文章编号: N21042810
期刊: Geochimica et Cosmochimica Acta
作者: Ziming Fang, Weifeng Yang, Aron Stubbins, Min Chen, Junjie Li, Renming Jia, Qi Li, Jing Zhu, Bo Wang
更新时间: 2021-04-28
摘要: In the Arctic, large amounts of black carbon (BC) are released into river water and transported to the oceans as dissolved BC (DBC). However, the cycling and fate of DBC in the ocean is poorly understood. Here, DBC, dissolved organic carbon (DOC), absorbance, and δ18O were analyzed to examine the spatial characteristics and removal of DBC in the western Arctic Ocean and the Bering Sea during the boreal summer. DBC concentrations ranged from 0.67 to 4.18 μmol-C L-1. In the sea-ice free regions, high DBC and DOC concentrations and a254 values corresponded to high δ18O-derived meteoric water contents, indicating that river discharge dominated their spatial patterns. By contrast, sea-ice meltwater (SIM) appeared to dilute DBC and DOC in SIM impacted waters (SIM>3.5%). The departure of DBC from conservative mixing lines suggested that 47-84% of riverine DBC was removed over the shelves with 7-23% transported to the upper Canada Basin. These results suggest that shelf regions are crucial sites for riverine DBC removal that modulate the delivery of DBC to the open Arctic Ocean.

17696. 题目: Incorporation of ozone-driven processes in a treatment line for a leachate from a hazardous industrial waste landfill: impact on the bio-refractory character and dissolved organic matter distribution
文章编号: N21042809
期刊: Journal of Environmental Chemical Engineering
作者: Inalmar D. Barbosa Segundo, Ana I. Gomes, Bianca M. Souza-Chaves, Minkyu Park, André B. dos Santos, Rui A.R. Boaventura, Francisca C. Moreira, Tânia F.C.V. Silva, Vítor J.P. Vilar
更新时间: 2021-04-28
摘要: The current work aimed to evaluate the feasibility of including ozone (O3)-based advanced oxidation processes (AOPs), as an intermediate step, in a multistage treatment system for non-biodegradable sulphur-rich leachate from a hazardous industrial solid waste landfill (HISWL), combining chemical and biological oxidation technologies. O3-based AOPs covered perozonation (O3/H2O2), photo-assisted ozonation (O3/UVC), and photo-assisted perozonation (O3/H2O2/UVC). All O3-driven processes were applied to HISWL leachate directly after sulphur compounds removal via catalytic oxidation and chemical precipitation. Moreover, ozonation was also tested after a sequential coagulation step using ferric or aluminium salts (O3/Fe2+ or O3/Al3+), and O3/H2O2/UVC system was likewise tried after Fe-mediated coagulation targeting photo-Fenton-assisted ozonation (O3/PF). The best-performing treatment train encompassed: (i) catalytic oxidation with H2O2 (stoichiometric amount) under free pH, to convert sulphite and sulphide ions into oxidised sulphur species, including sulphate; (ii) chemical precipitation of sulphate as barite mineral without pH correction; (iii) O3/H2O2 process for ca. 2.1-h (natural pH; room temperature; 3.5kg O3 and 1.1kg H2O2 per m3 leachate), to degrade refractory organic matter and improve biodegradability; and (iv) biological oxidation to remove the remaining bioavailable organics fraction. This four-stage approach allowed shifting from a highly recalcitrant wastewater to an effluent in full agreement with the regulation for industrial wastewater discharge into the municipal sewer network. Furthermore, the effectiveness of the O3/H2O2 process over the dissolved organic matter transformation was corroborated by fluorescence excitation-emission matrix and size exclusion chromatography analysis.

17697. 题目: Effects of soil organic matter on biochar application in developing the biodegradation potentials of polycyclic aromatic hydrocarbons (PAHs)
文章编号: N21042808
期刊: Applied Soil Ecology
作者: Lulu Kong, Baoping Song, Tiantian Zhang, Kangning Gao, Jingze Liu
更新时间: 2021-04-28
摘要: This study investigated polycyclic aromatic hydrocarbons (PAHs) removal with wheat straw–derived biochar prepared at 500 °C (WS500) in three different petroleum–contaminated soils. Biochar decreased the contents of PAHs, and its effect has been shown to be dependent upon soil type, especially the soil organic matter (SOM). WS500 exhibited strong adsorptive ability towards PAHs in Jingxing (JX) soil, while it enhanced the PAHs removal by adsorption in combination with biodegradation in Luquan (LQ) soil. No significant effect on PAHs removal was observed in WS500–amended Jinzhou (JZ) soil. PAHs with 4 rings were the most impacted by adding biochar. Principal Coordinates Analysis (PCoA) and clustering analysis indicated that microbial community's distribution was more soil type-related than biochar-related. Illumina MiSeq sequencing results revealed that Proteobacteria, Acidobacteria, Actinobacteria and Verrucomicrobia were the most dominant in all the investigated samples, and that most of the strains were Gram–negative. However, at the genus level a large shift in the bacterial community was observed in LQ soil after adding biochar with increased abundance of the potential PAHs degraders. Thus, the current study highlights the potential of SOM in affecting the PAHs biodegradation by biochar, which may be attributed to the impacted sorption behavior of pollutants and selective enrichment of PAHs degraders.

17698. 题目: Permafrost Thaw Increases Methylmercury Formation in Subarctic Fennoscandia
文章编号: N21042807
期刊: Environmental Science & Technology
作者: Brittany Tarbier, Gustaf Hugelius, Anna Britta Kristina Sannel, Carluvy Baptista-Salazar, Sofi Jonsson
更新时间: 2021-04-28
摘要: Methylmercury (MeHg) forms in anoxic environments and can bioaccumulate and biomagnify in aquatic food webs to concentrations of concern for human and wildlife health. Mercury (Hg) pollution in the Arctic environment may worsen as these areas warm and Hg, currently locked in permafrost soils, is remobilized. One of the main concerns is the development of Hg methylation hotspots in the terrestrial environment due to thermokarst formation. The extent to which net methylation of Hg is enhanced upon thaw is, however, largely unknown. Here, we have studied the formation of Hg methylation hotspots using existing thaw gradients at five Fennoscandian permafrost peatland sites. Total Hg (HgT) and MeHg concentrations were analyzed in 178 soil samples from 14 peat cores. We observed 10 times higher concentrations of MeHg and 13 times higher %MeHg in the collapse fen (representing thawed conditions) as compared to the peat plateau (representing frozen conditions). This suggests significantly greater net methylation of Hg when thermokarst wetlands are formed. In addition, we report HgT to soil organic carbon ratios representative of Fennoscandian permafrost peatlands (median and interquartile range of 0.09 ± 0.07 μg HgT g–1 C) that are of value for future estimates of circumpolar HgT stocks.

17699. 题目: Riverine carbon cycling over the past century in the Mid‐Atlantic region of the United States
文章编号: N21042806
期刊: Journal of Geophysical Research: Biogeosciences
作者: Yuanzi Yao, Hanqin Tian, Shufen Pan, Raymond G. Najjar, Marjorie A. M. Friedrichs, Zihao Bian, Hong‐Yi Li, Eileen E. Hofmann
更新时间: 2021-04-28
摘要: The lateral transport and degassing of carbon in riverine ecosystems is difficult to quantify on large spatial and long temporal scales, due to the relatively poor representation of carbon processes in many models. Here, we coupled a scale‐adaptive hydrological model with the Dynamic Land Ecosystem Model to simulate key riverine carbon processes across the Chesapeake and Delaware Bay Watersheds from 1900‐2015. Our results suggest that throughout this time period riverine CO2 degassing and lateral dissolved inorganic carbon fluxes to the coastal ocean contribute nearly equally to the total riverine carbon outputs (mean±standard deviation: 886 ± 177 Gg C∙yr–1 and 883 ± 268 Gg C∙yr–1, respectively). Following in order of decreasing importance are the lateral dissolved organic carbon flux to the coastal ocean (293 ± 81 Gg C∙yr–1), carbon burial (118 ± 32 Gg C∙yr–1), and lateral particulate organic carbon flux (105 ± 35 Gg C∙yr–1). In the early 2000s, carbon export to the coastal ocean from both the Chesapeake and Delaware Watersheds was only 15‐20% higher than it was in the early 1900s (decade), but showing twofold increase in standard deviation. Climate variability (changes in temperature and precipitation) explains most (225 Gg C∙yr–1) of the increase since 1900, followed by changes in atmospheric CO2 (82 Gg C∙yr–1), atmospheric nitrogen deposition (44 Gg C∙yr–1), and applications of nitrogen fertilizer and manure (27 Gg C∙yr–1); in contrast, land conversion has resulted in a 188 Gg C∙yr–1 decrease in carbon export.

17700. 题目: Dewaterability improvement and environmental risk mitigation of waste activated sludge using peroxymonosulfate activated by zero-valent metals: Fe0 vs. Al0
文章编号: N21042805
期刊: Chemosphere
作者: Jialin Liang, Xiaojian Liao, Maoyou Ye, Zhijie Guan, Zhihua Mo, Xian Yang, Shaosong Huang, Shuiyu Sun
更新时间: 2021-04-28
摘要: The stabilization and dewaterability of waste activated sludge (WAS) are essential factors for downstream disposal or reuse. Herein, two types of zero-valent metals, zero-valent iron (Fe0) and zero-valent aluminum (Al0), were compared for their ability to activate peroxymonosulfate (PMS) during the WAS conditioning process, with the effects of PMS activation by these two metals on WAS dewaterability and the potential environmental risks evaluated. Results showed that compared to Al0/PMS treatment, Fe0/PMS treatment achieved superior WAS dewaterability and reduced operational costs. Using PMS combined with Fe0 and Al0 treatments under optimal conditions, the water content (Wc) of dewatered sludge decreased to 55.7 ± 2.7 wt.% and 59.4 ± 1.3 wt.%, respectively. Meanwhile, application of the Fe0/PMS treatment system reduced the total annual cost by approximately 33.1%, compared to the Al0/PMS treatment. Analysis of the dewatering mechanism demonstrated that in the Fe0/PMS treatment, Fe3+/Fe2+ flocculation played an important role in the enhancement of WAS dewatering, while sulfate radical (SO4•−) oxidation was the dominant factor for WAS dewaterability improvement in Al0/PMS treatment. The greater enhancement of WAS dewaterability by Fe0/PMS treatment, was mainly attributed to more efficient reduction of hydrophilic extracellular polymeric substances (EPS) and an increase in surface charge neutralization. Environmental risk evaluation results indicated that Fe0/PMS and Al0/PMS treatments both effectively alleviated the environmental risks of heavy metals and faecal coliforms in dewatered sludge. Overall, this study proposes a novel perspective for the selection of an optimal PMS activator in sludge treatment.