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12901. 题目: Accelerated antimony and copper removal by manganese oxide embedded in biochar with enlarged pore structure
文章编号: N20071011
期刊: Chemical Engineering Journal
作者: Shunli Wan, Lian Qiu, Yan Li, Junjie Sun, Bin Gao, Feng He, Wubo Wan
更新时间: 2020-07-10

Antimony and copper pollution pose significant threat to water quality security, and their advanced treatment is still a great challenge. In this study, we fabricated a hybrid adsorbent (denoted as MO-L-BC) through dispersing manganese oxide (MO) inside a biochar with enlarged pore structure (namely L-BC). The used carrier L-BC possessed a high proportion of large pores (>2 nm) (87%), and thus lowered the diffusion resistance of target pollutants in pore region of MO-L-BC. Consequently, Sb(III) and Cu(II) adsorption onto MO-L-BC achieved equilibrium within 15 min, and their effective coefficients of intra-particle diffusion (D) were calculated to be 8.6 × 10−8 and 1.5 × 10−7 cm2 s−1, respectively, which were only one-order magnitude lower than that in aqueous phase. XPS analysis indicated that 53.3% of the sorbed Sb(III) was oxidized to Sb(V) by the impregnated MO. Coexisting substances such as HCO3, SO42−, NO3, Ca2+, Mg2+ and humic acid up to 20 times higher concentration than target contaminants (Sb(III) or Cu(II)) caused only < 20% drop in sorption capacity of MO-L-BC, and the mutual effect of Sb(III) and Cu(II) was also not noticeable. The fixed-bed column adsorption tests showed that MO-L-BC can achieve the tertiary treatment of either the singly polluted (Sb(III) or Cu(II)) or the co-contaminated wastewater at a high flow rate of 0.27 m h−1, with effective treatment volumes larger than400 BV, and the saturated MO-L-BC can be effectively regenerated. MO-L-BC is a promising engineered biochar to treat Sb(III) and/or Cu(II) contaminated water especially under high-flow conditions.

12902. 题目: Bayesian calibration of the DayCent ecosystem model to simulate soil organic carbon dynamics and reduce model uncertainty
文章编号: N20071010
期刊: Geoderma
作者: Ram B. Gurung, Stephen M. Ogle, F. Jay Breidt, Stephen A. Williams, William J. Parton
更新时间: 2020-07-10

Benefits of carbon sequestration in agricultural soils are well recognized, and process-based models have been developed to better understand sequestration potential. However, most studies ignore the uncertainty arising during model prediction—a critical requirement for scientific understanding, policy implementation and carbon emission trading. Furthermore, the dependencies created in process-based models due to many parameters and a relatively small set of empirical data hinder parameterization. We have implemented a Bayesian approach using the sampling importance resampling (SIR) method to calibrate the DayCent ecosystem model for estimating soil organic carbon (SOC) stocks, and to quantify uncertainty in model predictions. A SOC dataset compiled from 19 long-term field experiments, representing 117 combinations of management treatments, with 491 measurements of SOC, was split into independent datasets for model calibration and evaluation. The most important DayCent model parameters were identified through a global sensitivity analysis (GSA) for parameterization and SIR was used to calibrate the model and produce posterior distributions for the most sensitive parameters. On average, the Bayesian calibration reduced the model uncertainty by a factor of 6.6 relative to the uncertainty associated with the prior. The Bayesian model analysis framework will allow for ongoing updates to the model as new datasets and model structural improvements are made in future research, and overall provide a stronger basis for models to support policy and management decisions associated with GHG mitigation through C sequestration in agricultural soils.

12903. 题目: Interaction of perfluorooctanoic acid with extracellular polymeric substances - Role of protein
文章编号: N20071009
期刊: Journal of Hazardous Materials
作者: Wangwang Yan, Tingting Qian, Liang Zhang, Li Wang, Yan Zhou
更新时间: 2020-07-10

Perfluorooctanoic acid (PFOA) is nonbiodegradable, and adsorption is the main pathway for its removal in wastewater treatment plants (WWTPs). This study compared the capability of three types of sludge on adsorbing PFOA and investigated the role of extracellular polymeric substances (EPS) in the adsorption process. Results show that enhanced biological phosphorus removal (EBPR) sludge had the highest adsorption capacity for PFOA. Studies on the interaction between EPS and PFOA reveal that proteins play a crucial role in binding PFOA to EPS/sludge. Specifically, the aromatic and amide groups on the structure of protein can attract the C–F chains and carboxylic head of PFOA via hydrophobic interaction and electrostatic attraction, respectively. EPS of EBPR sludge has the highest amount of protein and binding sites, thus exhibits the highest adsorption capability for PFOA. This study reveals the interaction mechanism between PFOA and sludge EPS and provides new insight into the function of EPS in perfluoroalkyl substances removal in WWTPs.

12904. 题目: A review on facilitating bio-wastes degradation and energy recovery efficiencies in anaerobic digestion systems with biochar amendment
文章编号: N20071008
期刊: Bioresource Technology
作者: Gaojun Wang, Yu Li, Li Sheng, Yao Xing, Guohao Liu, Gaofei Yao, Huu Hao Ngo, Qian Li, Xiaochang C. Wang, Yu-You Li, Rong Chen
更新时间: 2020-07-10

In this review, progress in the potential mechanisms of biochar amendment for AD performance promotion was summarized. As adsorbents, biochar was beneficial for alleviating microbial toxicity, accelerating refractory substances degradation, and upgrading biogas quality. The buffering capacity of biochar balanced pH decreasing caused by volatile fatty acids accumulation. Moreover, biochar regulated microbial metabolism by boosting activities, mediating electron transfer between syntrophic partners and enriching functional microbes. Recent studies also suggested biochar as potential useful additives for membrane fouling alleviation in anaerobic membrane bioreactors (AnMBR). By analyzing the reported performances based on different operation models or substrate types, debatable issues and associated research gaps of understanding the real role of biochar in AD were critically discussed. Accordingly, Future perspectives of developing biochar-amended AD technology for real-world applications were elucidated. Lastly, with biochar-amended AD as a core process, a novel integrated scheme was proposed towards high-efficient energy-resource recovery from various bio-wastes.

12905. 题目: Biochar combined with gypsum reduces both nitrogen and carbon losses during agricultural waste composting and enhances overall compost quality by regulating microbial activities and functions
文章编号: N20071007
期刊: Bioresource Technology
作者: Jisong Qu, Lijuan Zhang, Xu Zhang, Lihong Gao, Yongqiang Tian
更新时间: 2020-07-10

Composting is an efficient method for treating agricultural wastes. This study investigated the effects of the addition of biochar (B) and gypsum (G) to straw mixed with chicken manure (SC) (i.e. SC, SC + B, SC + G and SC + B + G) on composting performance at different initial C/N ratios (20, 25 and 30). In general, biochar combined with gypsum (BCG) efficiently shortened composting time and reduced N loss, C loss and potential ecological risk. It also enhanced lignocellulose decomposition, nutrient retention and the overall compost quality expressed by a compost quality index (CQI), and increased the biomass of four different test crops. The BCG-induced increase in CQI was closely associated with microbial enzyme activities and C catabolic profiles. These results indicated that the combination of biochar and gypsum is more effective than each single additive during composting, and emphasized that microbial activities and functions play pivotal roles in determining compost quality and thereby agronomic performance.

12906. 题目: A Highly Efficient Strategy for Enhancing the Adsorptive and Magnetic Capabilities of Biochar Using Fenton Oxidation
文章编号: N20071006
期刊: Bioresource Technology
作者: Shuang Xu, Jihui Li, Zhibing Yin, Sen Liu, Siyao Bian, Yucang Zhang
更新时间: 2020-07-10

Fenton modification, involving iron-promoted pyrolysis followed by H2O2 oxidation, was first employed to improve the adsorptive and magnetic capabilities of biochar. Modified biochars were prepared from rubber tree bark and coconut shell through iron-promoted pyrolysis and subsequent H2O2 oxidation, and their adsorption behaviors toward Cr (VI) and MB were evaluated in aqueous solution. The modified biochars pyrolyzed at 300 and 400 ˚C displayed much higher adsorption capabilities than corresponding pristine biochars for Cr (VI) and MB, respectively, ascribing to introduction of COOH, C=O and C-O groups by Fenton oxidation. More importantly, saturation magnetization could be enhanced by transforming nonmagnetic iron oxides into γ-Fe2O3 through H2O2 oxidation. The removal of Cr (VI) and MB could be primarily contributed to the adsorption of biochar matrix by reduction/hydrogen bonding/cation exchange/electrostatic interaction and hydrogen bonding/cation exchange/electrostatic interaction, respectively. This would provide a novel and efficient strategy for making highly adsorptive magnetic biochar.

12907. 题目: Biochar affects the dissipation of antibiotics and abundance of antibiotic resistance genes in pig manure
文章编号: N20071005
期刊: Bioresource Technology
作者: Anastasiah N. Ngigi, Yong Sik Ok, Sören Thiele-Bruhn
更新时间: 2020-07-10

Manure from medicated livestock contains pharmaceutical antibiotics and antibiotic resistance genes (ARGs). Bioavailable antibiotics trigger further ARGs amplification during manure storage. It was tested whether biochar lowers the bioavailability of the antibiotics sulfamethazine (SMZ), ciprofloxacin (CIP), oxytetracycline (OTC) and florfenicol (FF) in manure and the amplification of sul1 and tet(W) ARGs. To that end, liquid pig manure was treated with 5% (w/w) pinecone biochar (BCP). Antibiotics dissipated during 30-d incubation in the order SMZ < OTC < CIP < FF. Added BCP further immobilized SMZ, OTC and CIP, while the effect was not significant for FF. Both sul1 and tet(W) ARGs copy numbers significantly increased by factors of 5.8 and 2.5, respectively, in OTC and SMZ spiked manure. The abundance of sul1 was significantly decreased in BCP amended manure, while the impact on tet(W) was less. Consequently, biochar is suitable for the management of antibiotics contaminated manure during storage.

12908. 题目: Combined application of biochar with urease and nitrification inhibitors have synergistic effects on mitigating CH4 emissions in rice field: A three-year study
文章编号: N20071004
期刊: Science of the Total Environment
作者: Tiehu He, Junji Yuan, Jiafa Luo, Stuart Lindsey, Jian Xiang, Yongxin Lin, Deyan Liu, Zengming Chen, Weixin Ding
更新时间: 2020-07-10

Biochar and inhibitors applications have been proposed for mitigating soil greenhouse gas emissions. However, how biochar, inhibitors and the combination of biochar and inhibitors affect CH4 emissions remains unclear in paddy soils. The objective of this study was to explore the effects of biochar application alone, and in combination with urease (hydroquinone) and nitrification inhibitors (dicyandiamide) on CH4 emissions and yield-scaled CH4 emissions during three rice growing seasons in the Taihu Lake region (Suzhou and Jurong), China. In Suzhou, N fertilization rates of 120–280 kg N ha−1 increased CH4 emissions compared to no N fertilization (Control) (P < 0.05), and the highest emission was observed at 240 kg N ha−1, possibly due to the increase in rice-derived organic carbon (C) substrates for methanogens. Biochar amendment combined with N fertilization reduced CH4 emissions by 13.2–27.1% compared with optimal N (ON, Suzhou) and conventional N application (CN-J, Jurong) (P < 0.05). This was related to the reduction in soil dissolved organic C and the increase in soil redox potential. Addition of urease and nitrification inhibitor (ONI) decreased CH4 emissions by 15.7% compared with ON treatment. Combined application of biochar plus urease, nitrification and double inhibitors further decreased CH4 emissions by 22.2–51.0% compared with ON and CN-J treatment. ON resulted in the highest yield-scaled CH4 emissions, while combined application of biochar alone and in combination with the inhibitors decreased yield-scaled CH4 emissions by 12.7–54.9% compared with ON and CN-J treatment (P < 0.05). The lowest yield-scaled CH4 emissions were observed under combined application of 7.5 t ha−1 biochar with both urease and nitrification inhibitors. These findings suggest that combined application of biochar and inhibitors could mitigate total CH4 and yield-scaled CH4 emissions in paddy fields in this region.

12909. 题目: Efficient vertical transport of black carbon in the planetary boundary layer
文章编号: N20071003
期刊: Geophysical Research Letters
作者: Dantong Liu, Kang Hu, Delong Zhao, Shuo Ding, Yunfei Wu, Chang Zhou, Chenjie Yu, Ping Tian, Quan Liu, Kai Bi, Yangzhou Wu, Bo Hu, Dongsheng Ji, Shaofei Kong, Bin Ouyang, Hui He, Mengyu Huang, Deping Ding
更新时间: 2020-07-10

Vertical distribution of black carbon (BC) determines the layer where its heating impacts exert. This study presents continuous and simultaneous measurements at surface, and on a mountain site above the wintertime planetary boundary layer influenced by uplifted surface anthropogenic emissions. BC was observed efficiently transported upwards by daytime convective mixing. However, this vertical transport was less for other particulate masses. An about two‐folds higher BC mass fraction was thus present at mountain than surface, hereby a lowered single‐scattering albedo (SSA) by 0.06. This may be caused by the evaporative loss of condensed semi‐volatile materials, prevailing the secondary particulate formation, in a cleaner environment containing less precursors. The elevated BC mass corresponded with the most intensive solar radiation at midday, wielding more heating impacts over the PBL. This phenomenon may apply to other remote regions where a reduced SSA will introduce more positive radiative effects.

12910. 题目: Black carbon aerosols in the lower free troposphere are heavily coated in summer but largely uncoated in winter at Jungfraujoch in the Swiss Alps
文章编号: N20071002
期刊: Geophysical Research Letters
作者: Ghislain Motos, Joel C. Corbin, Julia Schmale, Rob L. Modini, Michele Bertò, Piotr Kupiszewski, Urs Baltensperger, Martin Gysel‐Beer
更新时间: 2020-07-10

Black carbon (BC) particles are responsible for substantial radiative heating of the atmosphere. However, the climate‐relevant properties of BC particles in the free troposphere (FT) are poorly constrained over longer time scales. Here, we report on in‐situ, intensive field campaigns deploying a single‐particle soot photometer during summer and winter seasons at the Jungfraujoch (3580 m a.s.l., Switzerland), a site often located in the lower FT. The refractory BC (rBC) mass size distribution was very stable across the two seasons. BC was generally internally mixed (i.e. heavily coated with other aerosol material) in summer. However, against general expectations, BC was predominantly externally mixed in winter, with a high occurrence of negligibly‐to‐thinly coated BC. This strong seasonality in lower‐FT BC mixing state has not been previously observed, and would substantially influence the lifetime, loading, and climate effects of free‐tropospheric BC. Future measurements should investigate the generality of these results.

12911. 题目: Surface properties and suspension stability of low-temperature pyrolyzed biochar nanoparticles: Effects of solution chemistry and feedstock sources
文章编号: N20071001
期刊: Chemosphere
作者: Chen-Yang Xu, Qi-Rui Li, Zeng-Chao Geng, Fei-Nan Hu, Shi-Wei Zhao
更新时间: 2020-07-10

Intensive application of biochar requires better understanding of their environmental behaviors such as stability, fate, and mobility. The release of bulk biochar into biochar nanoparticles (NPs) may bring risks because of their potential flowing into downstream water bodies with nutrients/containments attached. Low-temperature pyrolyzed biochars, namely fruit tree branch biochar of 350/450/550 °C (FB350, FB450 and FB550), corn straw biochar of 350 °C (CB350) and peanut straw biochar of 350 °C (PB350), were produced, and their NPs were extracted. The yield, elemental composition, mineral composition, surface functional groups and zeta potential of biochar NPs were characterized. Subsequently their suspension stability was evaluated in NaCl and CaCl2 solutions by dynamic light scattering technique. The Hamaker constants and particle interaction energy of the biochar NPs were calculated by adopting Derjaguin–Landau–Verwey–Overbeek theory. For biochar NPs of same feedstock, the stability of FB350/450/550-NPs could be predicted well by their zeta potential values. The types of their surface functional groups were the same while their adsorption intensity differed. The scenarios for biochar NPs of different feedstock sources were different, that is, inconsistent variation was observed between their zeta potential and suspension stability, which were rooted in the variable type and quantity of surface functional groups. In conclusion, feedstock was the most significant factor that influenced the suspension stability of biochar NPs, followed by the pyrolysis temperature and solution chemistry, which were highly dependent on surface potential. The findings provide references for the environmental risk evaluation of biochar NPs and reasonable application of biochar in field.

12912. 题目: Effects of fulvic acids on the electrochemical reactions and mass transfer properties of organic cation toluidine blue: Results of measurements by the method of rotating ring-disc electrode
文章编号: N20070910
期刊: Water Research
作者: Siqi Liu, Weiqing Han, Gregory V. Korshin
更新时间: 2020-07-09

This study examined effects of aquatic and soil natural organic matter (NOM) exemplified by standard Suwannee River fulvic acid (SRFA) and Pahokee Peat fulvic acid (PPFA), respectively, on the electrochemical (EC) reactivity and mass transfer properties of the cationic organic probe toluidine blue (TB) that forms complexes with NOM. EC measurements that were carried out using the method of rotating ring-disc electrode (RRDE) showed that for disc potentials below −0.4 V vs. the standard Ag/AgCl reference electrode, TB molecules undergo EC reduction accompanied by the formation of EC-active products that undergo oxidation at the ring electrode. EC reactions of TB in the range of potentials −0.2 to −0.4 V were determined to involve free TB+ cations and TB species adsorbed on the electrode surface. The EC reduction of TB species at the disc potentials < −0.4 V was controlled by the mass transfer of the free TB+ cations and TB/NOM complexes to the electrode surface. Formation of TB/NOM complexes caused the mass transfer-controlled TB currents to undergo a consistent decrease. The observed changes were correlated with the extent of TB/NOM complexation and decreases of the diffusion coefficients of TB/NOM complexes that have higher molecular weights (MW) than the free cations. Properties of the intermediates formed upon the reduction of TB+ cations were also affected by NOM. These results demonstrate that RRDE measurements of EC reactions of TB or possibly other EC active probes allow probing the complexation of EC-active organic species with NOM and mass transfer properties of NOM complexes and ultimately NOM itself.

12913. 题目: Fate and removal of aromatic organic matter upon a combined leachate treatment process
文章编号: N20070909
期刊: Chemical Engineering Journal
作者: Min-Da Yu, Bei-Dou Xi, Zong-Qiang Zhu, Li Zhang, Chao Yang, Chun-Mao Geng, Xiao-Song He
更新时间: 2020-07-09

Mature leachates contain extremely recalcitrant aromatic organic matter, and require appropriate treatment before discharge. The combined process for treating mature landfill leachate is a common and proper due to its inexpensiveness and high performance. Identification of refractory components and insights into the physicochemical properties transformations of the organics are essential for the development of efficient treatment process. Optical, three-dimensional chromatography and electrochemical techniques were applied to characterize aromatic organic matter in leachate from a pilot landfill leachate treatment plant. Results showed that the combination of biological contact oxidation, iron-carbon micro-electrolysis, Fenton, coagulation and integrated activated sludge system could efficiently remove 95.5% COD and 88.3% DOC in leachate organic matter, together with a simultaneous reduction in its molecular weight (MW), aromaticity, polarity, and humification degree. The low MW proteinaceous, carboxylic acid and amine-containing fractions were preferentially removed in biological contact oxidation process, whereas the hydrophilic humic substances with the MW > 4.0 kDa were the main species against biological treatment. Conversely, the advanced oxidation processes (AOPs) could efficiently destroy high MW, aromatic rings and conjugated moieties fractions, resulting in an increase in the leachate biodegradability. The oxygen-containing moieties generated in the AOPs were bridged by the flocculants to promote precipitate during the coagulation process, and the polymerized metastable organic fractions formed during the process were partly biodegraded in the integrated activated sludge system. This study highlights the potential of combined optical-electrochemical measurements to monitor the intrinsic reactivity of aromatic organic matter and guide the practical leachate treatment.

12914. 题目: Carbon balance by priming as controlled by single versus repeated addition and soil fertility
文章编号: N20070908
期刊: Soil Biology and Biochemistry
作者: Lei Wu, Hu Xu, Qiong Xiao, Yaping Huang, Memon Muhammad Suleman, Ping Zhu, Yakov Kuzyakov, Xingliang Xu, Minggang Xu, Wenju Zhang
更新时间: 2020-07-09

Labile carbon (C) inputs strongly alter soil organic matter (SOM) turnover by priming, thus affecting soil C dynamics and over long-term the soil fertility. The input patterns of labile C regulating priming effect (PE) intensity, and consequently the soil C balance may differ between the experimentally single addition compared to naturally ongoing continuous inputs via rhizodeposits or litter decomposition. We evaluated the effects of single versus repeated additions of 13C-labeled glucose (with added 13C corresponding to 2% of soil organic C content) to five soils with increasing fertility level on the PE intensity and soil C balance. Repeated glucose addition induced 61–108% higher positive SOM priming than the single addition across the five soils. The PE intensity declined with soil fertility level and mineral nitrogen (N) content, but increased with activities of enzymes for N-acquisition (N-acetyl-glucosaminidase and leucine amino peptidase). Consequently, the decrease in N availability strongly increased PE intensity via enhancing microbial N mining from SOM. Considering the C balance between SOM losses by priming and glucose-C retention, glucose addition induced net C losses in the low and moderate fertility soils (−14.0 to −0.30 mg C g−1 SOC over 14 weeks) but C gains in the high fertility soils (+0.44 to +4.36 mg C g−1 SOC). The increase in soil fertility reduced priming intensity and increased glucose-C retention via high N availability and intensive microbial growth, thus promoting microbial necromass formation and so, soil C sequestration. Compared to single addition, repeated glucose addition caused larger net C losses or lower C gains due to stronger SOM priming. In conclusion, substrate addition pattern and soil fertility are crucial for regulating SOM priming and the C balance. This knowledge should be integrated to evaluate soil C dynamics in response to labile C inputs caused by agricultural managements.

12915. 题目: Rapid, high-sensitivity analysis of oxyhalides by non-suppressed ion chromatography-electrospray ionization-mass spectrometry: application to ClO4−, ClO3−, ClO2−, and BrO3− quantification during sunlight/chlorine advanced oxidation
文章编号: N20070907
期刊: Environmental Science: Water Research and Technology
作者: Tessora R. Young, Shi Cheng, Wentao Li, Michael C. Dodd
更新时间: 2020-07-09
摘要: A rapid and sensitive method is described for measuring perchlorate (ClO4), chlorate (ClO3), chlorite (ClO2), bromate (BrO3), and iodate (IO3) ions in natural and treated waters using non-suppressed ion chromatography with electrospray ionization and tandem mass spectrometry (NS-IC-MS/MS). Major benefits of the NS-IC-MS/MS method include a short analysis time (12 minutes), low limits of quantification for BrO3 (0.10 μg L−1), ClO4 (0.06 μg L−1), ClO3 (0.80 μg L−1), and ClO2 (0.40 μg L−1), and compatibility with conventional LC-MS/MS instrumentation. Chromatographic separations were generally performed under isocratic conditions with a Thermo Scientific Dionex AS16 column, using a mobile phase of 20% 1 M aqueous methylamine and 80% acetonitrile. The isocratic method can also be optimized for IO3 analysis by including a gradient from the isocratic mobile phase to 100% 1 M aqueous methylamine. Four common anions (Cl, Br, SO42−, and HCO3/CO32−), a natural organic matter isolate (Suwannee River NOM), and several real water samples were tested to examine influences of natural water constituents on oxyhalide detection. Only ClO2 quantification was significantly affected – by elevated chloride concentrations (>2 mM) and NOM. The method was successfully applied to quantify oxyhalides in natural waters, chlorinated tap water, and waters subjected to advanced oxidation by sunlight-driven photolysis of free available chlorine (sunlight/FAC). Sunlight/FAC treatment of NOM-free waters containing 200 μg L−1 Br resulted in formation of up to 263 ± 35 μg L−1 and 764 ± 54 μg L−1 ClO3, and up to 20.1 ± 1.0 μg L−1 and 33.8 ± 1.0 μg L−1 BrO3 (at pH 6 and 8, respectively). NOM strongly inhibited ClO3 and BrO3 formation, likely by scavenging reactive oxygen or halogen species. As prior work shows that the greatest benefits in applying the sunlight/FAC process for purposes of improving disinfection of chlorine-resistant microorganisms are realized in waters with lower DOC levels and higher pH, it may therefore be desirable to limit potential applications to waters containing moderate DOC concentrations (e.g., ∼1–2 mgC L−1), low Br concentrations (e.g., <50 μg L−1), and circumneutral to moderately alkaline pH (e.g., pH 7–8) to strike a balance between maximizing microbial inactivation while minimizing formation of oxyhalides and other disinfection byproducts.

12916. 题目: Characteristics of DOM in 14 AAO processes of municipal wastewater treatment plants
文章编号: N20070906
期刊: Science of the Total Environment
作者: Yufei Shi, Shengnan Li, Liye Wang, Juechun Li, Guochen Shen, Gang Wu, Ke Xu, Hongqiang Ren, Jinju Geng
更新时间: 2020-07-09

The characteristics of dissolved organic matter (DOM) such as chemical composition, molecular weight (MW) distribution and hydrophobic/hydrophilic distribution can affect wastewater treatment efficiency, effluent quality and ecological risk. Fluorescence spectroscopy could provide a quick estimate of DOM characteristics during the monitoring of wastewater treatment plants (WWTPs). In this study, the characteristic and quantitative correlation of DOM from 14 anaerobic-anoxic-oxic (AAO) processes of WWTPs located in different provinces (municipalities) of China were investigated. The results showed that DOM of MW <1 kDa was the largest group of DOM in influent and secondary effluent, and DOM removal increased as the MW increased. Hydrophilic (HPI) fraction and hydrophobic acid (HPO-A) comprised the major portion of DOM in influent and secondary effluent and exhibited the lowest rate of removal. In addition, DOM concentrations in the northern provinces were higher than in the southern provinces, which were related to the water quality, economy and population. There were positive correlations between specific fluorescence intensity (SFI) and the MW <1 kDa, 1–5 kDa and <10 kDa fractions. The smaller the molecular weight, the better the correlation. Strong positive correlations between regional fluorescence proportion (fi) and HPI were found. SFI and fi may be explored as potential indicators of the MW fractions and the hydrophobic/hydrophilic distribution of DOM in AAO processes WWTPs.

12917. 题目: Deciphering organic matter sources and ecological shifts in blue carbon ecosystems based on molecular fingerprinting
文章编号: N20070905
期刊: Science of the Total Environment
作者: Joeri Kaal, Antonio Martínez Cortizas, Miguel-Ángel Mateo, Oscar Serrano
更新时间: 2020-07-09
摘要: Blue carbon ecosystems (BCE) play an essential role in the global carbon cycle by removing atmospheric carbon dioxide and storing it as organic carbon (OC) in biomass and sediments. However, organic matter (OM) deposition and degradation/preservation processes are poorly understood, especially on the long-term and at molecular scales. We analysed sediment samples from six cores collected in tidal marshes, mangroves and seagrasses (up to 150 cm long cores spanning up to 10,000 yrs of OC accumulation) from Spencer Gulf (South Australia), by pyrolysis (Py-GC–MS and THM-GC–MS), and we compared the results with elemental and stable isotope data, to decipher OM provenance and to assess degradation/preservation dynamics. The results showed that: (1) the major biopolymers preserved were polysaccharides, polyphenolic moieties (lignin and tannin) and polymethylenic moieties (e.g. cutin, suberin, chlorophyll) with smaller apportions of proteins and resins; (2) the OM originates predominantly from vascular plant materials (in particular lignocellulose) that have been well-preserved, even in some of the oldest sediments; (3) mangroves were found to be the most efficient OC sinks, partially explained by syringyl lignin preservation; (4) seagrasses were shown to store polysaccharide-enriched OM; (5) large proportions of polycyclic aromatic hydrocarbons (PAHs) in surficial tidal marsh and mangrove sediments probably reflect pyrogenic OM from industrial combustion, and; (6) ecosystem shifts, i.e. mangrove encroachment in tidal marsh and transition from seagrass to mangrove, were detected. Deposition environment and source vegetation control OC sequestration and there is no specific recalcitrant form of OM that is selectively preserved. For the first time, we demonstrate how analytical pyrolysis in combination with stable isotope analysis can be used to reconstruct (palaeo-)ecological shifts between different BCE. This study improves our knowledge on OC accumulation dynamics and the response of BCE to environmental change, which can inform the implementation of strategies for climate change mitigation.

12918. 题目: Reduction mechanism of Cd accumulation in rice grain by Chinese milk vetch residue: Insight into microbial community
文章编号: N20070904
期刊: Ecotoxicology and Environmental Safety
作者: Siyuan Zhang, Yan Deng, Shaodong Fu, Menglong Xu, Ping Zhu, Yili Liang, Huaqun Yin, Luhua Jiang, Lianyang Bai, Xueduan Liu, Huidan Jiang, Hongwei Liu
更新时间: 2020-07-09

Chinese milk vetch is an efficient approach to reduce Cd accumulation in rice, nevertheless, its reduction mechanism is not well understood. In this study, we investigated the rice grain Cd, soil properties and microbial community in a Cd-polluted paddy field amended with milk vetch residue (MV) or without (CK) during rice growth period. We found that milk vetch residue averagely decreased the Cd content in rice grain by 45%. Decrease of Cd in rice mainly attributed to the inhibition of Cd activation by milk vetch residue at heading stage probably by the formation of HA-Cd (Humic Acid) and CdS. Increased pH and organic matter (OM) promoted the reduction of available Cd. In addition, nonmetric multidimensional scaling (NMDS) analysis revealed that microbial community structure was significantly different between MV and CK treatment (r = 0.187, p = 0.002), and the core functions of differentially abundant genera were mainly associated with N-cycling, organic matter degradation and sulfate-reducing. The application of milk vetch residue increased the abundance of sulfate-reducing bacteria (SRB) by 8–112% during the rice growth period, which may involve in promoting the transformation of Cd to a more stably residual Cd (CdS). Canonical correspondence analysis (CCA) and mantel test analysis indicated that available K (p = 0.004) and available N (p = 0.005) were the key environmental factors of shaping the SRB. Altogether, changes in soil properties affected microbial structure and functional characteristics, especially the response of SRB in MV treatment would provide valuable insights into reducing the bioavailability of Cd in soil.

12919. 题目: Seagrass losses since mid‐20th century fuelled CO2 emissions from soil carbon stocks
文章编号: N20070903
期刊: Global Change Biology
作者: Cristian Salinas, Carlos M. Duarte, Paul S. Lavery, Pere Masque, Ariane Arias‐Ortiz, Javier X. Leon, David Callaghan, Gary A. Kendrick, Oscar Serrano
更新时间: 2020-07-09

Seagrass meadows store globally significant organic carbon (Corg) stocks which, if disturbed, can lead to CO2 emissions, contributing to climate change. Eutrophication and thermal stress continue to be a major cause of seagrass decline worldwide, but the associated CO2 emissions remain poorly understood. This study presents comprehensive estimates of seagrass soil Corg erosion following eutrophication‐driven seagrass loss in Cockburn Sound (23 km2 between 1960s and 1990s) and identifies the main drivers. We estimate that shallow seagrass meadows (<5 m depth) had significantly higher Corg stocks in 50 cm thick soils (4.5 ± 0.7 kg Corg/m2) than previously vegetated counterparts (0.5 ± 0.1 kg Corg/m2). In deeper areas (>5 m), however, soil Corg stocks in seagrass and bare but previously vegetated areas were not significantly different (2.6 ± 0.3 and 3.0 ± 0.6 kg Corg/m2, respectively). The soil Corg sequestration capacity prevailed in shallow and deep vegetated areas (55 ± 11 and 21 ± 7 g Corg m−2 year−1, respectively), but was lost in bare areas. We identified that seagrass canopy loss alone does not necessarily drive changes in soil Corg but, when combined with high hydrodynamic energy, significant erosion occurred. Our estimates point at ~0.20 m/s as the critical shear velocity threshold causing soil Corg erosion. We estimate, from field studies and satellite imagery, that soil Corg erosion (within the top 50 cm) following seagrass loss likely resulted in cumulative emissions of 0.06–0.14 Tg CO2‐eq over the last 40 years in Cockburn Sound. We estimated that indirect impacts (i.e. eutrophication, thermal stress and light stress) causing the loss of ~161,150 ha of seagrasses in Australia, likely resulted in the release of 11–21 Tg CO2‐eq since the 1950s, increasing cumulative CO2 emissions from land‐use change in Australia by 1.1%–2.3% per annum. The patterns described serve as a baseline to estimate potential CO2 emissions following disturbance of seagrass meadows.

12920. 题目: Optical and chemical analysis of absorption enhancement by mixed carbonaceous aerosols in the 2019 Woodbury, AZ fire plume
文章编号: N20070902
期刊: Journal of Geophysical Research: Atmospheres
作者: James E. Lee, Manvendra K. Dubey, Allison C. Aiken, Petr Chylek, Christian M. Carrico
更新时间: 2020-07-09

Wildfires emit mixtures of light‐absorbing aerosols (including black and brown carbon, BC and BrC, respectively) and more purely‐scattering organic aerosol (OA). BC, BrC and OA interactions are complex and dynamic and evolve with aging in the atmosphere resulting in large uncertainties in their radiative forcing. We report microphysical, optical and chemical measurements of multiple plumes from the Woodbury Fire (AZ, USA) observed at Los Alamos, NM after 11‐18 hours of atmospheric transit. This includes periods where the plumes exhibited little entrainment as well as periods that had become more dilute after mixing with background aerosol. Aerosol mass absorption cross‐sections (MAC) were enhanced by a factor of 1.5‐2.2 greater than bare‐BC at 870 nm suggesting lensing by non‐absorbing coatings following a core‐shell morphology. Larger MAC enhancement factors of 1.9‐5.1 at 450 nm are greater than core‐shell morphology can explain and are attributed to BrC. MAC of OA (MACOrg) at 450 nm was largest in intact portions of the plumes (peak value bounded between 0.6‐0.9 m2/g (Org)) and decreased with plume dilution. We report a strong correlation between MACOrg(450 nm) with the fC2H4O2 (a tracer for levoglucosan‐like species) of coatings and of bulk OA indicating that BrC in the Woodbury Fire was co‐emitted with levoglucosan, a primary aerosol. fC2H4O2 and MACOrg(450 nm) are shown to vary between the edge and the core of plumes demonstrating enhanced oxidation of OA and BrC‐bleaching near plume edges. Our process‐level finding can inform parameterizations of mixed BC, BrC and OA properties for wildfire plumes in climate models.

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