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25161. 题目: Combined process of visible light irradiation photocatalysis-coagulation enhances natural organic matter removal: Optimization of influencing factors and mechanism
文章编号: N19060713
期刊: Chemical Engineering Journal
作者: Nan Wang, Xing Li, Yanling Yang, Yi Shang, Xiaoxuan Zhuang, Hang Li, Zhiwei Zhou
更新时间: 2019-06-07
摘要: Photocatalysis or coagulation process has been separately studied for the removal of natural organic matter (NOM) from surface water, and the reaction mechanism of organic fractionations of treated effluent has been clarified. Although coagulation-based process has been extensively studied for NOM removal, few attempts have been made based on a combined process that can not only efficiently degrade NOM, but also enhance the coagulation performance. The hypothesis is that a combination of photocatalysis and coagulation process in a single unit might potentially enhance NOM removal efficiency. This is because the nano-photocatalyst can serve as both pre-oxidant and flocculation core. Herein, a combined process of visible light photocatalysis prior to coagulation is conducted, with the transformation efficiency of the organics fractionations revealed. The as-prepared nano-sized photocatalyst consisting of Bi2O3-TiO2 (molar Bi/Ti ratio 0.04:1) had a stronger visible light absorption ability. Compared to coagulation alone, the combined photocatalysis-coagulation process greatly improved NOM removal, with synergistic effect, while the pre-photocatalysis reduced the required dosage of polyaluminium chloride (PACl) coagulant and increased the optimal pH of solution. A mathematical model optimized by response surface methodology of the combined process was developed that produced a good correlation between predicted and experimental values. The optimal conditions were calculated as follow: 2.0 g/L photocatalyst, a photocatalytic reaction time of 10 min 18 sec, 0.04 mM PACl coagulant, and a pH of 4.2. These conditions particularly enhanced removal of acidic hydrophobic substance, humic-/protein-like substances and fractions with molecular weight between 3 and 44 kDa. The XRD spectra and SEM images of the produced flocs identified that these flocs consisted of a core of photocatalyst, which could contribute to an effective flocculation and enhanced NOM removal.
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25162. 题目: Sulfur isotopic composition of gas-phase organic sulfur compounds provides insights into the thermal maturation of organic-rich rocks
文章编号: N19060712
期刊: Geochimica et Cosmochimica Acta
作者: Alon Amrani, Yoav Oved Rosenberg, Alexander Meshoulam, Ward Said-Ahmad, Courtney Turich, Nathalie Luu, Tracey Jacksier, Artur Stankiewicz, Shimon Feinstein, Avital Shurki
更新时间: 2019-06-07
摘要: Volatile and gas phase organic sulfur compounds (VOSCs) are important components in subsurface reservoir fluids and despite their relatively low concentrations, can provide important information about organic matter origin, diagenetic transformation, thermal maturation, and oil and gas generation, expulsion, and migration. We present an approach for the utilization of VOSC concentration and compound specific S isotopes ratio (δ34S) data as a new geochemical tool to study natural gas origin and formation. We studied the formation pathways of VOSCs, their δ34S values, and interaction with an organic-rich sedimentary rock (or ‘source rock’) from the Ghareb Formation (Type II-S kerogen) deposited in an upwelling marine environment. The immature source rock was subjected to laboratory controlled thermal maturation. We used a semi-open, non-isothermal pyrolysis system heated between 200 and 440 °C, and analyzed the molecular composition and compound specific δ34S values of the evolved gases at various thermal maturity stages. Formation of VOSCs commenced at 206°C, a temperature generally associated with less thermally mature systems, and typically before the onset of oil generation for similar organic-rich source rocks, allowing study of low thermal maturity conditions (∼0.3 %Roe). Overall, the VOSCs obtained had δ34S values similar to the bulk kerogen values (mostly within 4‰). However, thiol (or mercaptan) δ34S values closely followed those of H2S (Δ34Sthiols-H2S = -1±1‰) throughout the experiment. Quantum chemistry calculations (ab-initio) for the S isotopic exchange between H2S and thiols were close to the experimental observations. This suggests that thiols rapidly attained equilibrium with H2S despite their very short residence time in the system (minutes to hours). Furthermore, throughout the experiment, the concentrations of the six different thiols were found to be proportional to the coexisting, concentration ratio of [H2]/[H2S]. The proportionality factors of the 6 different thiols strongly correlate with reported heats of formation (ΔHf°), further supporting the notion that the generation of thiols in the system rapidly reached equilibrium. At pyrolysis temperatures up to 350°C, δ34S and concentration values of other VOSCs produced in the gas phase, including sulfides and thiophenes, probably represent generation from S-containing moieties in kerogen and bitumen with limited interaction with co-existing H2S. The reaction of hydrocarbons and H2S to produce VOSCs is inversely correlated with thermal stability, i.e. thiols > sulfides > thiophenes. Therefore, the δ34S values, concentrations and distributions of VOSCs can be utilized as a proxy for reaction extent and formation mechanism of petroleum and H2S, including primary generation by thermal maturation, or potentially other processes such as migration and thermochemical sulfate reduction. This work demonstrates a novel and useful geochemical tool to study the source and fate of natural gas in the subsurface.
25163. 题目: Controls on volatile fatty acid concentrations in marine sediments (Baltic Sea)
文章编号: N19060711
期刊: Geochimica et Cosmochimica Acta
作者: Clemens Glombitza, Matthias Egger, Hans Røy, Bo Barker Jørgensen
更新时间: 2019-06-07
摘要: Volatile fatty acids (VFA) are key intermediates in the degradation pathway of organic matter (OM) in marine sediments. They are products of fermentation and are utilized as substrates in the terminal steps of microbial OM mineralization, such as sulfate reduction and methanogenesis. We studied the distribution of formate, acetate, propionate and butyrate concentrations in the pore water throughout 100-m deep sedimentary sequences in the Baltic Sea. The sediments included both sulfate and methane zones and were retrieved during the Integrated Ocean Drilling Program Expedition 347. VFA concentrations were consistently low throughout the sulfate and methane zones, ranging from few hundred nanomolar to about hundred micromolar, thus pointing to efficient microbial utilization in the terminal OM mineralization steps in both zones. Concentrations of formate followed a different depth trend than the other three VFAs suggesting a different mechanistical control of the formate turnover. Calculations of the Gibbs energy reveal that acetoclastic methanogenesis is exergonic (up to -30 kJ (mol CH4)-1) throughout the sulfate zone and suggest that methanogens can potentially coexist with sulfate reducers in the sulfate zone while sharing acetate as a substrate. In the deeper methane rich sediments, the energy yield of acetoclastic methanogenesis is generally very low (less negative than -10 kJ (mol CH4)-1). The uniformly low acetate concentrations in the methane zone suggest its active microbial turnover but the pathway from acetate to methane still remains unclear. Interestingly, acetoclastic sulfate reduction still yields at least -20 kJ (mol sulfate)-1 in the methane zone and, thus, sulfate reducers may utilize acetate as electron donor in the methane zone, which is in agreement with the earlier findings of sulfate reducers in methanogenic sediments.
25164. 题目: Linking chromophoric organic matter transformation with biomarker indices in a marine phytoplankton growth and degradation experiment
文章编号: N19060710
期刊: Marine Chemistry
作者: Michael R. Shields, Thomas S. Bianchi, Christopher L. Osburn, Joanna D. Kinsey, Kai Ziervogel, Astrid Schnetzer, Gabrielle Corradino
更新时间: 2019-06-07
摘要: The production and transformation of marine chromophoric dissolved organic matter (CDOM) provides a window into the marine biological pump as it is present at all depths and can be measured both in the field and via satellite. However, outside of lignin for terrestrial DOM, few studies have linked marine CDOM characteristics with biomarker indices. In this study, we quantified five fluorescent components of marine CDOM and base-extractable particulate organic matter (BEPOM) in a growth and degradation experiment using a natural plankton assemblage, and compared those results to bacterial abundances, hydrolytic enzyme activities, and amino acid concentrations and associated diagenetic indices. Rotating glass bottles containing plankton were sampled initially (day 0), during the mid-exponential (day 13) and stationary (day 20) growth phases, and again following a dark degradation period that lasted 42 days. Protein-like fluorescence (tryptophan-like and tyrosine-like) was correlated with the total amino acid concentrations for both the DOM and BEPOM through all phases of the incubation. However, tryptophan-like fluorescence showed a stronger correlation for aromatic amino acids. The concentration of particulate organic carbon changed significantly during each phase of the experiment and this substrate correlated with hydrolytic enzyme activities and bacterial abundance. This heterotrophy diagenetically altered the POM during the stationary phase and ultimately resulted in the increased production of more humic-like CDOM after degradation in the dark. Results from this study indicate that CDOM formation and cycling may play a prominent role in the ocean's nitrogen cycle.
25165. 题目: A mechanistic model of photochemical transformation and degradation of colored dissolved organic matter
文章编号: N19060709
期刊: Marine Chemistry
作者: J. Blake Clark, Patrick Neale, Maria Tzortziou, Fang Cao, Raleigh R. Hood
更新时间: 2019-06-07
摘要: Photochemical degradation (PD) of colored dissolved organic matter (CDOM) is a key transformational process for both natural and anthropogenic DOM. A fully mechanistic model is presented that can simulate laboratory incubations of the controlled PD of marsh and estuarine derived CDOM. The model was designed and optimized to recreate the loss of absorbance for marsh low tide and estuarine samples, representing high molecular weight allochthonous and mid molecular weight estuarine CDOM. In the model, high specific absorbance fractions representative of marsh and estuarine CDOM are transformed into a low specific absorbance fraction representative of coastal ocean CDOM as well as non-colored fractions. The various transformations in the model have maximum apparent quantum yields (at 284 nm) that range from 3.22 × 10−8 ± 1.75 to 56.05 ± 21.5 [mmol C (mol photons)−1], with non-colored DOM/inorganic carbon production outpaced by inter-molecular organic carbon transformations. Model performance was tested using an independent incubation data set whereby experimental results of photobleaching of spectral absorbance at 300 nm were recreated with a Willmott model skill of 0.98 and mean percent error of −3.66%. The production of the low molecular weight photodegraded end member ranged from 0.52 to 4.86 μmol C L−1 h−1.
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25166. 题目: Black carbon in a glacier and snow cover on the northeastern Tibetan Plateau: Concentrations, radiative forcing and potential source from local topsoil
文章编号: N19060708
期刊: Science of The Total Environment
作者: Yang Li, Shichang Kang, Jizu Chen, Zhaofu Hu, Kun Wang, Rukumesh Paudyal, Jingshi Liu, Xiaoxiang Wang, Xiang Qin, Mika Sillanpää
更新时间: 2019-06-07
摘要: Black carbon (BC), which consists of the strongest light-absorbing particles (LAP) in snow/ice, has been regarded as a potential factor accelerating the melting of glaciers and snow cover over the Third Pole. During the winter and summer of 2016, snow, ice and topsoil were sampled from the Laohugou basin located on the northeastern Tibetan Plateau. Concentrations of BC in Laohugou Glacier No. 12 (LG12) and snow cover in this basin (LSC) varied broadly (21.7–2700.1 and 89.6 to 6326.2 ng g−1, respectively), indicating large spatiotemporal variability in wet, dry and post depositional conditions. Further, internally mixed BC in snow grains enhanced the albedo reduction (15.0–26.3%) more than externally mixed BC in LG12 and LSC. Dust played a more important role than BC in accelerating the melting of LG12, whereas these components played comparable roles in accelerating the melting of LSC. In total, externally mixed BC and dust reduced the albedo by 0.075–0.423, with an associated mean radiative forcing (RF) of 97.5 ± 41.5 Wm−2 in LSC. This level was lower than those in the ablation zone (354.1 ± 81.2 Wm−2) and accumulation zone (145.6 ± 76.7 Wm−2) of LG12 because of discrepancies in LAP concentrations, solar zenith angles and incoming shortwave radiation. Furthermore, we observed that topsoil containing abundant BC was transported along the slope from the debris to the LG12 surface ice, and topsoil in this region could be lifted by strong mountain-valley winds and then deposited on snow/ice surfaces, which affected the LAP concentrations. Therefore, this study is important for understanding the role of BC and dust in the melting of snow/ice in the northeastern Tibetan Plateau.
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25167. 题目: Variations of physical and chemical properties in relation to erythromycin mycelial dreg dewaterability under heat-activated persulfate oxidation conditioning
文章编号: N19060707
期刊: Science of The Total Environment
作者: Yanxiang Zhang, Huiling Liu, Xiaohu Dai, Chen Cai, Jing Wang, Yunpeng Shen, Peng Wang
更新时间: 2019-06-07
摘要: Erythromycin mycelial dreg (EMD) resulting from erythromycin (ERY) production process may be used as a nutrient resource. However, it has a high moisture content, which makes handling operations complicated. In this study, the EMD dewaterability under heat-activated persulfate (PS) oxidation conditioning was investigated. The variations of physical and chemical properties of EMD were further investigated to uncover the underlying mechanism of EMD dewaterability. Results indicated that EMD dewaterability was worse under single heat process, but significantly improved under heat-activated PS oxidation process. Heat-activated PS oxidation conditioning was capable to increase zeta potential, reduce median particle size, alter EMD flocs morphology, and disrupt mycelial cells. Concurrently, heat-activated PS oxidation conditioning resulted in the decrease of protein in tightly bound (TB) extracellular polymeric substances (EPS) and total EPS, and the decrease of fluorescing constituents (tryptophan protein, tyrosine protein and tryptophan amino acid) in EPS. Furthermore, a possible mechanism was proposed for heat-activated PS oxidation conditioning.
25168. 题目: High-resolution three-dimensional mapping of soil organic carbon in China: Effects of SoilGrids products on national modeling
文章编号: N19060706
期刊: Science of The Total Environment
作者: Zongzheng Liang, Songchao Chen, Yuanyuan Yang, Yue Zhou, Zhou Shi
更新时间: 2019-06-07
摘要: Soil organic carbon (SOC) is a key factor in soil fertility and structure and plays an important role in the global carbon cycle. However, SOC causes a large uncertainty in Earth System Models for predicting future climate change. The GlobalSoilMap (GSM) project aims to provide global digital soil maps of primary functional soil properties at six standard depth intervals (0–5, 5–15, 15–30, 30–60, 60–100, and 100–200 cm) with a grid resolution of 90 × 90 m. Currently, few SOC national products that meet the GSM specifications are available. This study describes the three-dimensional spatial modeling of SOC maps according to GSM specifications. We used 5982 soil profiles collected during the Second National Soil Survey of China, along with 16 environmental covariates related to soil formation. The results were obtained by parallel computing over tiles of 100 × 100 km, and the predictions for the tiles were subsequently merged into a single SOC map for the whole of China per standard GSM depth interval. For each standard GSM depth interval, SOC contents and their uncertainties were predicted and mapped at a spatial resolution of approximately 90 m using bootstrapping. Southwestern and northeastern China had higher SOC contents than the rest of China did, whereas northwestern China had a lower SOC content. The range of the coefficient of determination for the six depth intervals ranged from 0.35 to 0.02, and the mean SOC content was 17.86–8.67 g kg−1. Both these values decreased strongly with increasing soil depth. Cropland SOC content was lower than that of forest and grassland. The results of variable importance show that SoilGrids data were the best predictors for defining the soil-landscape relationship during regression modeling for SOC. These SOC maps can provide a data source for environmental modeling, a benchmark against which to evaluate and monitor SOC dynamics, and a guide for the design of future soil surveys.
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25169. 题目: Effective removal by coagulation of contaminants in concentrated leachate from municipal solid waste incineration power plants
文章编号: N19060705
期刊: Science of The Total Environment
作者: Xu Ren, Ximeng Xu, Yu Xiao, Weiming Chen, Kai Song
更新时间: 2019-06-07
摘要: Municipal solid waste (MSW) incineration is widely used in China. Concentrated leachate, containing high concentrations of pollutants, is an important type of secondary pollution produced in MSW incineration power plants and requires proper treatment. In this study, various coagulants were used to treat concentrated leachate from a nanofiltration (NF) membrane that treated leachate from an MSW incineration plant. The optimal coagulation condition was determined in this study. Under the optimal condition, removals of chemical oxygen demand, light absorbing substances (at 254 nm), total nitrogen, color and turbidity were 68.42%, 69.01%, 44.14%, 92.31% and 87.44%, respectively. Much of the refractory organic matter with relatively high molecular weight, aromaticity and humification degree was removed, and effluent had a lower molecular weight than raw NF concentrated leachate. Study also found that some parts of high molecular weight compounds from NF CL were removed by coagulation process, but the change of distribution of molecular weight was not outstanding. The NF concentrated leachate, both before and after coagulation, contained a large amount of chloride. Hence, a follow-up study should be conducted to find an effective additional processing that can remove organic matter using the high concentration of chloride in the NF concentrated leachate coagulation effluent. This study provides a theoretical basis for the treatment of concentrated leachate from MSW incineration power plants.
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25170. 题目: Comparing three Australian natural organic matter isolates to the Suwannee river standard: Reactivity, disinfection by-product yield, and removal by drinking water treatments
文章编号: N19060704
期刊: Science of The Total Environment
作者: Kalinda Watson, Maria José Farré, Nicole Knight
更新时间: 2019-06-07
摘要: Water treatments that provide efficient removal of organic and inorganic disinfection by-product (DBP) precursors across variable natural organic matter (NOM) sources are desirable. Treatments that effectively remove inorganic DBP precursors such as bromide, which significantly shift the speciation of DBP formation towards more toxic DBPs, are of particular interest and have been less investigated.This study characterised NOM isolated from three major drinking water sources in Southeast Queensland (SEQ), Australia, and compared it to the International Humic Substances Society (IHSS) Suwannee River NOM isolate (SR) in terms of DBP precursor removal treatments and DBP formation. Each NOM isolate was used to make synthetic water samples with otherwise identical water quality parameters, that were treated with enhanced coagulation (EC) or EC followed by; anion exchange (MIEX® resin), powdered activated carbon (PAC), granular activated carbon (GAC) or silver impregnated activated carbon (SIAC), to investigate the removal of DBP precursors (bromide and DOC), minimisation of DBPs, as well as the change in specific chlorine demand. EC/SIAC treatment was the most effective method of DBP control studied, due to the efficient simultaneous NOM and bromide adsorption of the SIAC (99 ± 1% bromide removal regardless of NOM source). This treatment also resulted in >92% removal of each of the measured DBPs across all NOM sources, with the exception of DBAN and 1,1-DCP, which achieved >80% removal across all NOM sources. Increases in tribromomethane (TBM) and dibromoacetonitrile (DBAN) formation were observed after all other treatment/NOM-isolate combinations, due to increased Br:DOC ratio after treatment, whereas chlorinated DBPs were generally well-controlled by all treatment/NOM-isolate combinations. Differences in reactivity of the individual NOM isolates were found to be related to both the origin of the isolate and the treatment employed, however, bromide removal capacity for each treatment was independent of NOM source.
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25171. 题目: Post-agricultural restoration: Implications for dynamics of soil organic matter pools
文章编号: N19060703
期刊: CATENA
作者: Olga Kalinina, Alexander Cherkinsky, Oleg Chertov, Sergey Goryachkin, Irina Kurganova, Valentin Lopes de Gerenyu, Dmitry Lyuri, Yakov Kuzyakov, Luise Giani
更新时间: 2019-06-07
摘要: In order to bridge the gap of knowledge in respect of soil organic matter (SOM) dynamics of post-agricultural Luvisols during restoration, the study focused on alteration processes of functionally different SOM pools, 14C ages, and C turnover rates in a chronosequential approach. The study comprises three Luvisol chronosequences of 37 years (North), 120 years (Middle), and 42 years (South) across a climate gradient of the temperate broad-leaved forests of European Russia. Restoration led to SOM accumulation within both active (free particulate organic matter (POM) and occluded POM and passive (clay fraction) pools, and as a result, in gains of total organic carbon (C). Accumulation of new C was confirmed by increasing ∆14C signatures of occluded POM and clay fractions. After 22 years of restoration, ∆14C signatures progressed from negative to positive values for the occluded POM fraction, whereas they showed a similar development but remained negative for the clay faction. This highlights the fact that the incorporation of new C into the passive pool takes place, but that it occurs at a slower rate compared to that of the active pool. The 14C age of occluded POM fraction declined from 600 to 1200 years before present (BP) in arable sites to about 200 years BP after 22 years of restoration and thereafter. The 14C age of the clay fraction decreased from 1670 to 2660 years BP in arable soils to 750 years BP in 22 year abandoned site, 450–310 years BP in 32–66 year abandoned sites, and 200–370 years BP in near-natural forests. This decline of the 14C age reveals a change of the proportions between old and young C within the passive pool caused by management and the development of an ecosystem towards a steady state. Recovery of C was accompanied by initially increasing and then decreasing turnover rates of SOM, both again, much more pronounced in the active pool. These dynamics trace an initial ecosystem disturbance after abandonment, which slows down with time. Although C recovery and adjusted turnover rates of SOM progressed towards a new steady state of ecosystem; full restoration was not achieved within the chronosequential time scale of 120 years.
25172. 题目: Soil organic carbon density and its driving factors in forest ecosystems across a northwestern province in China
文章编号: N19060702
期刊: Geoderma
作者: Jin-Hong Guan, Lei Deng, Jian-Guo Zhang, Qiu-Yue He, Wei-Yu Shi, Guoqing Li, Sheng Du
更新时间: 2019-06-07
摘要: Forest soils are an important component of the global carbon cycle, as they sequester and store much more organic carbon than other terrestrial ecosystems. Thus, reliable information on the forest soil organic carbon (SOC), along with the factors that influence it, is crucial from the perspective of regional carbon budgets and climate modeling. Gansu Province in northwestern China is characterized by complex climatic gradients and diverse forest types, suggesting a large variability in the spatial distribution of SOC, yet the SOC stock in this region has not been comprehensively investigated because of insufficient soil profile data. Our study covered the entire forest area in the province via a regional-scale sampling campaign, and provided soil organic carbon density (SOCD) data obtained from 112 natural forests and 100 plantations. Influencing factors including forest type, forest stand age, soil type, litter carbon, climate, and topography were evaluated in both natural forests and plantations. The results indicated a SOC stock of 433.4 ± 13.2 Tg C and a SOCD value of 175.3 ± 33.0 Mg C ha−1 for the 0–100 cm layer at the regional scale. Specifically, the SOC stock and the forest area-weighted average SOCD in natural forests were estimated at 349.0 ± 16.5 Tg C and 207.3 ± 23.2 Mg C ha−1, which were about quadruple and double, respectively, of the values for the plantations. Regardless of natural forests and plantations, SOCD increased with both stand age class and elevation and decreased with mean annual temperature (MAT). SOCD also increased with mean annual precipitation (MAP) for natural forests with elevation <2500 m and for all plantations. The overall importance to SOCD of the explanatory variables increased with increasing soil depth in natural forests while decreased with increasing soil depth in plantations. Forest type, stand age, soil type, MAT, MAP, elevation, litter carbon, slope, and aspect explained 58 and 65% of the total variation in the SOCD at 100 cm depth in natural forests and plantations, respectively. In natural forests, the most important explanatory variable for the uppermost 30 cm was soil type, while it was MAT for the whole 100 cm; in plantations, the most prominent factors were forest type and elevation, regardless of the soil depth. These suggest that environmental changes will likely have different effects on SOCD in natural forests and plantations.
25173. 题目: Quantifying soil quality in a horticultural-cover cropping system
文章编号: N19060701
期刊: Geoderma
作者: Inderjot Chahal, Laura L. Van Eerd
更新时间: 2019-06-07
摘要: Understanding and interpretation of soil quality is crucial to strategize land management practices for sustaining agricultural productivity while mitigating environmental degradation. A medium-term cover crop (CC) trial, established in 2007 and repeated in 2008, at Ridgetown, Ontario was used to evaluate the comprehensive assessment of soil health (CASH), to develop a weighted soil quality index (WSQI), and to compare scores of CASH, Haney soil health test (HSHT), and WSQI in surface soil (15 cm) in 2015 and 2016 (herein referred to as site-years). Out of 25 potential soil quality indicators, 19 soil indicators were responsive to CC treatments and represented a total dataset. Using principal component analysis (PCA) of the total dataset, a minimum dataset (five indicators; pH, organic matter (OM), Solvita labile amino N (SLAN), Solvita CO2-burst, and water extractable organic C (WEOC)) was identified to calculate a WSQI. The WSQI and CASH scores were equivalent in detecting CC treatment differences in site-year 2015, but CASH detected greater magnitude (12.1%) of treatment differences than WSQI (5.7%) in site-year 2016. Cereal rye and a mixture of oilseed radish and rye (OSR + Rye) led to greater soil quality values than other tested CCs. Our results indicate the potential of CCs in significantly improving soil quality in the medium-term (6 years). This study is the first independent evaluation of CASH in a horticultural system in a humid, temperate climate, and first study to compare WSQI with commercial soil quality tests. Even though CASH and WSQI differentiated between CC treatments for soil quality evaluation in both site-years, we recommend WSQI as a valuable and practical tool (lesser number of indicators; five vs. 15), for quantifying soil quality in similar production regions and climatic conditions.
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25174. 题目: Development of CuO coated ceramic hollow fiber membrane for peroxymonosulfate activation: a highly efficient singlet oxygen-dominated oxidation process for bisphenol A degradation
文章编号: N19060614
期刊: Applied Catalysis B: Environmental
作者: Songxue Wang, Jiayu Tian, Qiao Wang, Feng Xiao, Shanshan Gao, Wenxin Shi, Fuyi Cui
更新时间: 2019-06-06
摘要: A CuO coated ceramic hollow fiber membrane with dual functionalities of membrane filtration and peroxymonosulfate (PMS) activation was successfully constructed by applying phase-inversion and dip-coating technologies. The CuO coating condition was investigated, and the optimized CuO coated ceramic hollow fiber membranes ([email protected]) exhibited excellent catalytic activity for PMS activation to depredate bisphenol A (BPA) in the presence of humic acid (HA), chloride ions (Cl-) and bicarbonate (HCO3-). Based on the scavenger experiments and electron paramagnetic resonance (EPR) analyses, the non-radical reactive oxygen species - singlet oxygen (1O2), rather than sulfate radicals (SO4•-) or hydroxyl radicals (•OH), was elucidated as the primary reactive species responsible for the oxidation of BPA in the system. The redox circles of Cu(II)/Cu(I) on the CuO surface of the [email protected] are mainly responsible for PMS activation and a possible degradation pathway of BPA was proposed. Moreover, the [email protected] exhibited excellent stability and reusability without tedious catalyst separation/recovery processes. This study is meaningful for the development of novel catalytic membrane with PMS activation functionality in water treatment.
25175. 题目: Controls on the formation of turbidity current channels associated with marine-terminating glaciers and ice sheets
文章编号: N19060613
期刊: Marine Geology
作者: Ed L. Pope, Alexandre Normandeau, Colm Ó. Cofaigh, Chris R. Stokes, Peter J. Talling
更新时间: 2019-06-06
摘要: Submarine channels, and the sediment density flows which form them, act as conduits for the transport of sediment, macro-nutrients, fresher water and organic matter from the coast to the deep sea. These systems are therefore significant pathways for global sediment and carbon cycles. However, the conditions that permit or preclude submarine channel formation are poorly understood, especially when in association with marine-terminating glaciers. Here, using swath-bathymetric data from the inner shelf and fjords of northwest and southeast Greenland, we provide the first paper to analyse the controls on the formation of submarine channels offshore of numerous marine-terminating glaciers. These data reveal 37 submarine channels: 11 offshore of northwest Greenland and 26 offshore of southeast Greenland. The presence of channels is nearly always associated with: (1) a stable glacier front, as indicated by the association with either a moraine or grounding-zone wedge; and (2), a consistent seaward sloping gradient. In northwest Greenland, turbidity current channels are also more likely to be associated with larger glacier catchments with higher ice and meltwater fluxes which provide higher volumes of sediment delivery. However, the factors controlling the presence of channels in northwest and southeast Greenland are different, which suggest some complexity about predicting the occurrence of turbidity currents in glacier-influenced settings. Future work on tidewater glacier sediment delivery rates by different subglacial processes, and the role of grain size and catchment/regional geology is required to address uncertainties regarding the controls on channel formation.
25176. 题目: The fate of litter-derived dissolved organic carbon in forest soils: results from an incubation experiment
文章编号: N19060612
期刊: Biogeochemistry
作者: Min Wang, Qiuxiang Tian, Chang Liao, Rudong Zhao, Dongya Wang, Yu Wu, Qianxi Li, Xinggang Wang, Feng Liu
更新时间: 2019-06-06
摘要: Despite being a crucial component of nutrient cycling and soil carbon (C) dynamics in forest ecosystems, there is too little information from past studies to discern whether dissolved organic carbon (DOC) exchanges with soil organic carbon or passes unaltered through soils. In this study, we added 13C-labelled litter-derived DOC into different depth soil columns in a 180-day incubation experiment to determine the fate of DOC in soils, and to monitor the changes in DOC composition when it percolates through the soil. The results showed that δ13C values increased in soil microbes, which indicated that some litter-derived DOC was immobilized by soil microbial communities. Approximately 76% of litter-derived DOC was retained in the soil (60% in topsoil and 16% in midsoil). Meanwhile, 18%, 4%, and 3% of litter-derived DOC were mineralized into CO2 in topsoil, midsoil and subsoil respectively. Only 0.04% of litter-derived DOC leached from the soil column (0–60 cm). These results indicated that DOC was mainly retained on soil, and a small portion was mineralized by microorganisms, with minimal leaching. The composition of water soluble soil organic carbon (WSOC) and leachate DOC (LDOC) were similar between the control and treatment. This indicated that the composition of WSOC and LDOC was more similar to soil C than the added DOC, which supports the previously hypothesized dynamic exchange model. These findings provide new insight by showing that most litter-derived DOC is sequestered in forest soils.
25177. 题目: Recovery of organic matter and microbial biomass after abandonment of degraded agricultural soils depends on climate
文章编号: N19060611
期刊: Land Degradation & Development
作者: Lilit Ovsepyan, Irina Kurganova, Valentin Lopes de Gerenyu, Yakov Kuzyakov
更新时间: 2019-06-06
摘要: After abandonment of agricultural lands (ongoing on 220 Mio ha worldwide), degraded arable soils undergo self‐restoration and development towards natural ecosystems. We studied the linkage between microbial properties and density fractions of soil organic matter (SOM) during post‐agricultural restoration of former arable Phaeozems and Chernozems. The chronosequence study was conducted in two contrasting bioclimatic zones of European Russia: deciduous forest (Luvic Phaeozem) and dry steppe (Calcic Chernozem). Each chronosequence included an arable soil, 3–4 soils with increasing periods after abandonment (from 7 to 35 years), and reference sites with native soils. The basal respiration (BR) and microbial biomass (Cmic) were closely correlated with the soil organic carbon (Corg) and total nitrogen (TN) content as well as SOM density fractions: free particulate organic matter (fPOM), occluded particulate organic matter (oPOM), and mineral–SOM. The greatest increase in most properties was common in the top 0–5 cm and was maximal for fPOM and oPOM fractions (by 1.5–2.5 times), Cmic (1.9 times), and BR (1.5–2.5 times). For the first time, the duration of full recovery of soil properties depending on climate were estimated. Generally, ca. 40–120 and 20–30 years in the forest and steppe, respectively, are required to restore Corg, TN, and Cmic contents in the 0–5 cm layer after the abandonment of agricultural lands. The maximal restoration rates of all properties are common in the first 15–20 years after abandonment.
25178. 题目: Effects of agricultural land use change on organic carbon and its labile fractions in the soil profile in an urban agricultural area
文章编号: N19060610
期刊: Land Degradation & Development
作者: Youlin Luo, Qiquan Li, Jie Shen, Changquan Wang, Bing Li, Shu Yuan, Bin Zhao, Huanxiu Li, Junwen Zhao, Lingke Guo, Shan Li, Yuting He
更新时间: 2019-06-06
摘要: The properties of soil organic carbon (SOC) required for carbon sequestration and nutrient availability are contradictory, and the changes in SOC caused by agricultural land use changes remain elusive. Data on the total soil organic carbon (TOC) and labile organic carbon (LOC), including easily oxidizable organic carbon (EOC), dissolved organic carbon (DOC) and microbial biomass carbon (MBC), of the soil profile were analysed for four typical agricultural land use scenarios in the Chengdu Plain, China. The impacts of agricultural land use changes on sequestration and nutrient availability of SOC were assessed in this urban agricultural area using the space‐for‐time substitution method. Conversion of land use from a traditional agricultural rotation to afforestation increased the MBC content and decreased the contents of EOC, DOC and TOC due to the lower input of organic matter, improved aeration of the soil profile and growth of aboveground biomass. Conversion of a traditional rotation to a rice–garlic rotation resulted in a significant increase in topsoil TOC, slight but insignificant decreases in subsoil TOC, and clear increases in LOC because of rice planting, rice straw mulch and reasonable application of chemical fertilizers. In contrast, the conversion of a traditional rotation to a rice‐leafy vegetable rotation decreased MBC due to the excessive use of chemical fertilizers that consequently increased EOC, DOC and TOC. We conclude that afforestation on paddy soil has negative consequences for soil carbon sequestration, and a rice‐leafy vegetable rotation contributes to carbon sequestration but is detrimental to soil fertility. In addition, the MBC ratio in soil could be the optimal indicator for assessing SOC stability and soil fertility, and more attention should be paid to subsoil carbon changes.
25179. 题目: Anthropogenic nitrogen enrichment enhances soil carbon accumulation by impacting saprotrophs rather than ectomycorrhizal fungal activity
文章编号: N19060609
期刊: Global Change Biology
作者: Nadia I. Maaroufi, Annika Nordin, Kristin Palmqvist, Niles J. Hasselquist, Benjamin Forsmark, Nicholas P. Rosenstock, Håkan Wallander, Michael J. Gundale
更新时间: 2019-06-06
摘要: There is evidence that anthropogenic nitrogen (N) deposition enhances carbon (C) sequestration in boreal forest soils. However, it is unclear how free‐living saprotrophs (bacteria and fungi, SAP) and ectomycorrhizal (EM) fungi responses to N addition impact soil C dynamics. Our aim was to investigate how SAP and EM communities are impacted by N enrichment and to estimate whether these changes influence decay of litter and humus. We conducted a long‐term experiment in northern Sweden, maintained since 2004, consisting of ambient, low N additions (0, 3, 6 and 12 kg N ha−1 yr−1) simulating current N deposition rates in the boreal region, as well as a high N addition (50 kg N ha−1 yr−1). Our data showed that long‐term N enrichment impeded mass loss of litter, but not of humus, and only in response to the highest N addition treatment. Further, our data showed that EM fungi reduced the mass of N and P in both substrates during the incubation period compared to when only SAP organisms were present. Low N additions had no effect on microbial community structure, while the high N addition decreased fungal and bacterial biomasses and altered EM fungi and SAP community composition. Actinomycetes were the only bacterial SAP to show increased biomass in response to the highest N addition. These results provide a mechanistic understanding of how anthropogenic N enrichment can influence soil C accumulation rates and suggest that current N deposition rates in the boreal region (≤ 12 kg N ha−1 yr−1) are likely to have a minor impact on the soil microbial community and the decomposition of humus and litter.
25180. 题目: Recovery of Cr(III) by using chars from the co-gasification of agriculture and forestry wastes
文章编号: N19060608
期刊: Environmental Science and Pollution Research
作者: Delfina Godinho, Miguel Nogueira, Maria Bernardo, Diogo Dias, Nuno Lapa, Isabel Fonseca, Filomena Pinto
更新时间: 2019-06-06
摘要: The aim of the present work was to assess the efficiency of biochars obtained from the co-gasification of blends of rice husk + corn cob (biochar 50CC) and rice husk + eucalyptus stumps (biochar 50ES), as potential renewable low-cost adsorbents for Cr(III) recovery from wastewaters. The two gasification biochars presented a weak porous structure (ABET = 63–144 m2 g−1), but a strong alkaline character, promoted by a high content of mineral matter (59.8% w/w of ashes for 50CC biochar and 81.9% w/w for 50ES biochar). The biochars were used for Cr(III) recovery from synthetic solutions by varying the initial pH value (3, 4, and 5), liquid/solid (L/S) ratio (100–500 mL g−1), contact time (1–120 h), and initial Cr(III) concentration (10–150 mg L−1). High Cr(III) removal percentages (around 100%) were obtained for both biochars, due to Cr precipitation, at low L/S ratios (100 and 200 mL g−1), for the initial pH 5 and initial Cr concentration of 50 mg L−1. Under the experimental conditions in which other removal mechanisms rather than precipitation occurred, a higher removal percentage (49.9%) and the highest uptake capacity (6.87 mg g−1) were registered for 50CC biochar. In the equilibrium, 50ES biochar presented a Cr(III) removal percentage of 27% with a maximum uptake capacity of 2.58 mg g−1. The better performance on Cr(III) recovery for the biochar 50CC was attributed to its better textural properties, as well as its higher cation exchange capacity.