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14641. 题目: Physicochemical properties of biochar derived from anaerobically digested dairy manure
文章编号: N18092212
期刊: Waste Management
作者: Qianli Ma, Wei Song, Ruibin Wang, Jie Zou, Rendang Yang, Shuangbao Zhang
更新时间: 2018-09-22
摘要: Biochar was produced from anaerobically digested dairy manure under different processing temperatures (300, 600 and 1000 °C). The process could transform the biomass waste to high-value-added biochar products in high efficiency as well as reduce the manure biological pollution to the environment. By the results of thermogravimetric analysis (TGA) two kinetic models (FWO and Starink) were used to evaluate the activation energy. The biochar was studied for its surface area and pore size, chemical functionality, and crystalline structure by BET analysis, Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD). More porous and channel structures were observed under higher temperature and inert gas atmosphere, as characterized by scanning electron microscopy (SEM). The biochar with tunable physicochemical properties that was produced under different temperatures may be used for soil amendment or other fields.

14642. 题目: Facile synthesis of nano ZnO/ZnS modified biochar by directly pyrolyzing of zinc contaminated corn stover for Pb(II), Cu(II) and Cr(VI) removals
文章编号: N18092211
期刊: Waste Management
作者: Changjing Li, Lei Zhang, Yuan Gao, Aimin Li
更新时间: 2018-09-22
摘要: Nowadays, nano mineral modified biochars show a promising adsorption capacity for pollutants removals by combining the advantages of porous structure of biochar and unique property of nano minerals. In this work, nano ZnO/ZnS modified biochar was synthesized from slow pyrolysis of the zinc contaminated corn stover obtained from a biosorption process. The characterization results indicated that the zinc mineral modified biochar had a better porous structure (BET = 397.4 m2 g−1 and TPV = 0.43 cm3 g−1) than the common biochar (BET = 102.9 m2 g−1 and TPV = 0.20 cm3 g−1), and zinc minerals were evenly anchored on the biochar surface as nano ZnO/ZnS. Batch sorption experiments show that the obtained nano ZnO/ZnS modified biochar had strong sorption ability to Pb(II), Cu(II) and Cr(VI) with maximum sorption capacities of 135.8, 91.2 and 24.5 mg g−1, respectively, which were significantly higher than the common biochar (63.29, 27.05 and 15.23 mg g−1, respectively). The adsorption kinetics of heavy metal ions on nano ZnO/ZnS modified biochar were well described by the pseudo-second-order model, and the adsorption behavior coincided with heterogeneous adsorption materials as reflected by well fitting the Freundlich model. The thermodynamic results indicated that the adsorption process was an endothermic and spontaneous process. Based on the comprehensive characterizations and adsorption performance, the enhancement of the metals removal by the nano ZnO/ZnS modified biochar were mainly attributed to the hydroxyl groups on the surface of nano ZnO/ZnS particles and well-developed porous structure catalyzed by zinc salt during pyrolysis process. These findings suggested that generation of nano mineral modified biochar from heavy metals polluted biomass could be an attractive approach to treating and utilizing the waste biomass with a highly technical and economic feasibility.
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14643. 题目: Biochars and hydrochars prepared by pyrolysis and hydrothermal carbonisation of pig manure
文章编号: N18092210
期刊: Waste Management
作者: G. Gascó, J. Paz-Ferreiro, M.L. Álvarez, A. Saa, A. Méndez
更新时间: 2018-09-22
摘要: Pyrolysis of organic wastes for biochar preparation has been proved as a useful way of waste management. However, the elevated water content of some organic wastes precludes its use without a drying step before pyrolysis treatment. For this reason, hydrothermal carbonization (HTC) of wet biomass could be an inexpensive alternative management method. The main objective of the present work is to compare the properties of biochars and hydrochars obtained from thermal treatment of pig manure. Biochars were prepared at 300 °C (BPM300), 450 °C (BPM450) and 600 °C (BPM600) and hydrochars were obtained using a pig manure solution (ratio 30:70) that was heated at 200 °C (HPM200), 220 °C (HPM220) and 240 °C (HPM240) during 2 h. Characterization of biochar and hydrochar samples showed that pyrolysis led to chars with more aromatic structures and high thermal stability while HTC process originated chars with more aliphatic structures. HPM220 and HPM240 showed the highest values of field capacity water content and available water probably due to their higher O/C ratios and the macroporosity development in the range from 200 to 30,000 nm. These results suggested that HTC could be an interesting method to obtain soil growing media or green roof materials with adequate hydrophysical properties.

14644. 题目: Contribution and stability of forest-derived soil organic carbon during woody encroachment in a tropical savanna. A case study in Gabon
文章编号: N18092209
期刊: Biology and Fertility of Soils
作者: T. Chiti, A. Rey, K. Jeffery, M. Lauteri, V. Mihindou, Y. Malhi, F. Marzaioli, L. J. T. White, R. Valentini
更新时间: 2018-09-22
摘要: In this study, we quantified the contribution of forest-derived carbon (FDC) to the soil organic C (SOC) pool along a natural succession from savanna (S) to mixed Marantaceae forest (MMF) in the Lopè National Park, Gabon. Four 1-ha plots, corresponding to different stages along the natural succession, were used to determine the SOC stock and soil C isotope composition (δ13C) to derive the FDC contribution in different soil layers down to 1 m depth. Besides, to investigate changes in SOC stability, we determined the 14C concentration of SOC to 30 cm depth and derived turnover time (TT). Results indicated that SOC increased only at the end of the succession in the MMF stage, which stored 46% more SOC (41 Mg C ha−1) in the 0–30 cm depth than the S stage (28.8 Mg C ha−1). The FDC contribution increased along forest succession affecting mainly the top layers of the initial successional stages to 15 cm depth and reaching 70 cm depth in the MMF stage. The TT suggests a small increase in stability in the 0–5 cm layer from S (146 years) to MMF (157 years) stages. Below 5 cm, the increase in stability was high, suggesting that FDC can remain in soils for a much longer time than savanna-derived C. In conclusion, the natural succession toward Marantaceae forests can positively impact climate change resulting in large SOC stocks, which can be removed from the atmosphere and stored for a much longer time in forest soils compared to savanna soils.

14645. 题目: Regional patterns in the geochemistry of oil-field water, southern San Joaquin Valley, California, USA
文章编号: N18092208
期刊: Applied Geochemistry
作者: Peter B. McMahon, Justin T. Kulongoski, Avner Vengosh, Isabelle M. Cozzarelli, Matthew K. Landon, Yousif K. Kharaka, Janice M. Gillespie, Tracy A. Davis
更新时间: 2018-09-22
摘要: Chemical and isotopic data for water co-extracted with hydrocarbons in oil and gas fields are commonly used to examine the source of the formation water and possible impacts on groundwater in areas of oil and gas development. Understanding the geochemical variability of oil-field water could help to evaluate its origin and delineate possible contamination of shallow aquifers in cases where oil-field water is released to the environment. Here we report geochemical and multiple isotope (H, C, O, Sr, Ra) data from 22 oil wells, three sources of produced water that are disposed of in injection wells, and two surface disposal ponds in four oil fields in the southern San Joaquin Valley, California (Fruitvale, Lost Hills, North and South Belridge). Correlations between Cl and δ18O, as well as other ions, and gradual increases in salinity with depth, indicate dilution of one or more saline end-members by meteoric water. The saline end-members, represented by deep samples (610 m–2621 m) in three oil-bearing zones, are characterized by NaCl composition, near-seawater Cl concentrations (median 20,000 mg/L), enriched δ18OH2O (median 3.4‰), high ammonium (up to 460 mg-N/L), and relatively high radium activity (226Ra+228Ra = 12.3 Bq/L). The deepest sample has low Na/Cl (0.74), high Ca/Mg (5.0), and low 87Sr/86Sr (0.7063), whereas the shallower samples have higher Na/Cl (0.86–1.2), Ca/Mg near 1, and higher 87Sr/86Sr (∼0.7083). The data are consistent with an original seawater source being modified by various depth and lithology dependent diagenetic processes. Dilution by meteoric water occurs naturally on the east side of the valley, and in association with water-injection activities on the west side. Meteoric-water flushing, particularly on the east side, results in lower solute concentrations (minimum total dissolved solids 2730 mg/L) and total radium (minimum 0.27 Bq/L) in oil-field water, and promotes biodegradation of dissolved organic carbon and hydrocarbon gases like propane. Acetate concentrations and δ13C of dissolved inorganic carbon indicate biogenic methane production occurs in some shallow oil zones. Natural and human processes produce substantial variability in the geochemistry of oil-field water that should be considered when evaluating mixing between oil-field waters and groundwater. The variability could result in uncertainty as to detecting the potential source and impact of oil-field water on groundwater.

14646. 题目: Toward understanding the binding of Zn in soils by two-dimensional correlation spectroscopy and synchrotron-radiation-based spectromicroscopies
文章编号: N18092207
期刊: Geoderma
作者: Fu-Sheng Sun, Guang-Hui Yu, Matthew L. Polizzotto, Wei Ran, Qi-Rong Shen
更新时间: 2018-09-22
摘要: Zinc (Zn) is an essential micronutrient that is generally deficient in soils to accommodate plant needs. Therefore, it is imperative to enhance the concentration and availability of Zn in soils and plants through fertilization. Currently, however, the binding characteristics and fate of Zn in soils under various fertilization regimes remain unclear. Here, two-dimensional correlation spectroscopy (2DCOS) and synchrotron-radiation-based spectromicroscopies were used to identify functional groups responsible for Zn binding in soils following different fertilization treatments. The results showed that a 23-year long-term manure application significantly increased the concentrations of Zn in both soil and corn grain as compared to those having received a traditional inorganic NPK treatment. The 2DCOS analysis of FTIR spectra showed that aliphatic C mainly contributed to Zn binding in the NPK-treated soils, whereas SiO groups played a dominant role for Zn binding in the manure-treated soils. In soil dissolved organic matter, Zn2+ was first bound with FeO, followed by aliphatic C and polysaccharide C in the NPK treatment, but bound with aliphatic CH prior to SiO in the manure treatment. Furthermore, synchrotron-radiation-based FTIR and μ-XRF spectromicroscopies indicated that the distribution of Zn, clay minerals, sesquioxides and C functional groups was heterogeneous at the micro-scale, suggesting a heterogeneous binding site for Zn in soils. Using μ-XRF spectromicroscopies, a strong spatial correlation at the submicron scale between Fe and Zn was found in soils, suggesting that Fe-bearing minerals, likely Fe (hydr) oxides, contributed binding sites for Zn. Together, these results indicate that combining 2DCOS and synchrotron-radiation-based spectromicroscopies yields useful information for exploring the binding mechanisms among micronutrients, minerals and organic components in soils, particularly revealing how binding sites for micronutrients in soils can be modified according to fertilization regime.
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14647. 题目: A novel soil amendment for enhancing soil moisture retention and soil carbon in drought-prone soils
文章编号: N18092206
期刊: Geoderma
作者: Cynthia M. Kallenbach, Richard T. Conant, Francisco Calderón, Matthew D. Wallenstein
更新时间: 2018-09-22
摘要: Crop yield reductions are common in drought-stressed agroecosystems and are likely to become more frequent with climate change. To combat this, soil amendments are often used to enhance soil moisture retention but typically only lead to marginal improvements. Moreover, even as concern over agricultural water use mounts, a large fraction of food is wasted. Diverting more food waste and byproducts back to agricultural fields could reduce waste issues while ameliorating critical water limitations. We evaluated lactobionate, a lactose derivative and major dairy industry byproduct, as a potential soil amendment for enhancing both soil moisture and soil organic carbon (SOC). Lactobionate (LB) is a hydrophilic compound consisting primarily of cations and simple sugar acids. These combined properties could synergistically modify numerous controls on soil-water balances.In a laboratory setting, we compared LB stabilized with various cations (K+, NH4+, and Ca+) across a range of soil types to determine LB effects on soil moisture and SOC retention. All LB amendments increased soil water content relative to unamended soil across a range of soil matric potentials and raised available water content by 37%. Additionally, LB amended soils had on average 70 times more microbial biomass and decreased soil inorganic nitrogen content compared to unamended soils. We found that K+-LB, the most effective amendment, increased soil water content by 100–600% compared to unamended soils and as much as 87% of the increased SOC following LB additions was retained after 2 months. Our results suggest that tapping into novel sources of organic inputs such as LB may be an effective approach for simultaneously enhancing soil moisture and carbon stocks while increasing the economic and energetic value of food production byproducts.

14648. 题目: Variation of soil anaerobic microorganisms connected with anammox processes by 13C-phospholipid fatty acid analysis among long-term fertilization regimes in a crop rotation system
文章编号: N18092205
期刊: Applied Soil Ecology
作者: Qichun Zhang, Hua Jin, Huifang Zhou, Mei Cai, Yong Li, Gengmiao Zhang, Hongjie Di
更新时间: 2018-09-22
摘要: An anaerobic incubation experiment was conducted to evaluate the impacts of different fertilizer treatments on the activity and diversity of anaerobic bacteria combined anammox process. The treatments included no fertilization (CK), inorganic fertilization (IF), pig manure combined with inorganic fertilization (PF), and straw combined inorganic fertilization (SF) during wheat and rice seasons. Various 13C-PLFAs, especially 14:0, 16:1ω9c, 16:1ω5c, 16:0, 18:1ω9c, and 18:0, played significant roles in the anammox reaction and could be biomarkers of anammox. Additionally, fertilizer practices and seasonal changes could significantly affect soil properties, microbial biomass, and bacterial community structure. The abundance of total 13C and anaerobic microbes was higher in the PF and SF treatments than in the IF and CK treatments in the same season, indicating anaerobic activity and abundance can be enhanced by applying organic–inorganic compound fertilizers. The anammox microbial abundance, marked by the 13C-PLFAs 14:0, 16:1ω9c, 16:1ω5c, 16:0, 18:1ω9c, and 18:0, increased significantly during the crop rotation from the wheat season to the rice season. The proportions of bacteria were higher than those of fungi however the proportions of fungi were much higher than those of actinomycetes in all soils, suggest that fungi also play an important role in metabolizing the 13C-matrix with strong anaerobic activity.
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14649. 题目: Short-term effects of thinning on soil CO2, N2O and CH4 fluxes in Mediterranean forest ecosystems
文章编号: N18092204
期刊: Science of The Total Environment
作者: Gianluigi Mazza, Alessandro E. Agnelli, Paolo Cantiani, Ugo Chiavetta, Foteini Doukalianou, Kyriaki Kitikidou, Elias Milios, Michail Orfanoudakis, Kalliopi Radoglou, Alessandra Lagomarsino
更新时间: 2018-09-22
摘要: In Mediterranean ecosystems an increasing demand for in situ trace gas exchange data is emerging to enhance the adaptation and mitigation strategies under forest degradation. Field-chamber green-house gas fluxes and site characteristics were analysed in two Mediterranean peri-urban pine forests showing degradation symptoms. We examined the effect of different thinning interventions on soil CO2, CH4 and N2O fluxes, addressing the relationships with the environmental variables and C and N contents along forest floor-soil layers.Soil temperature resulted as the main driving variable for CO2 efflux and CH4 uptake. Soil moisture content and organic matter availability affected CO2 emission patterns in the two sites. N2O fluxes showed a positive correlation with soil moisture under wetter climatic conditions only. GHG fluxes showed significant correlations with C and N content of both forest floor and mineral soil, especially in the deepest layers, suggesting that it should be considered, together with environmental variables when accounting GHG fluxes in degraded forests.Short-term effects of thinning on CO2 emissions were dependent on disturbance induced by logging operations and organic matter inputs. After thinning CH4 uptake increased significantly under selective treatment, independently from specific site-induced effects. N2O fluxes were characterized by low emissions in both sites and were not affected by treatments. Soil CO2 efflux was the largest component of global warming potential (GWP) from both sites (11,553 kg ha−1 y−1 on average). Although it has a large global warming potential, N2O contribution to GWP was about 131 kg CO2eq ha−1 y−1. The contribution of CH4-CO2 equivalent to total GWP showed a clear and significant CH4 sink behaviour under selective treatment (36 kg ha−1 y−1 on average). However, in the short-term both thinning approaches produced a weak effect on total GWP.
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14650. 题目: Optimization and toxicity assessment of a combined electrocoagulation, H2O2/Fe2+/UV and activated carbon adsorption for textile wastewater treatment
文章编号: N18092203
期刊: Science of The Total Environment
作者: Edison GilPavas, Izabela Dobrosz-Gómez, Miguel-Ángel Gómez-García
更新时间: 2018-09-22
摘要: In this study, the potential application of sequential Electrocoagulation + Fenton (F) or Photo-Fenton (PF) + Active carbon adsorption (EC + F/PF + AC) processes were analyzed as alternatives for the treatment of an industrial textile wastewater resulting from an industrial facility located in Medellín (Colombia). In order to maximize the organic matter degradation, each step of the treatment was optimized using the Response Surface Methodology. At first, the optimal performance of EC was achieved with Fe electrodes operating at pH = 7, jEC = 10 mA/cm2 and 60 rpm, during 10 min of electrolysis. At these conditions, EC let to remove 94% of the dye's color, 56% of the COD and 54% of the TOC. Next, sequentially applied Fenton or photo-Fenton process (i.e., EC + F/PF), operating at the optimized conditions (pH = 4.3, [Fe2+] = 1.1 mM, [H2O2] = 9.7 mM, stirring velocity = 100 rpm and reaction time = 60 min.), improved the quality of the treated effluent. The EC + F let to achieve total color reduction, as well as COD and TOC removals of 72 and 75%, respectively. The EC + PF reached 100% of color, 76% of COD and 78% of TOC reductions. The EC + F/PF processes were more efficient than EC in elimination of low molecular weight (<5 kDa) compounds from wastewater. Moreover, the BOD5/COD ratio increased from 0.21 to 0.42 and from 0.21 to 0.46 using EC + F and EC + PF processes, respectively. However, EC + F/PF were not fully effective for the removal of acute toxicity to Artemia salina: 20% and 60% of reduction in toxicity using EC + F and EC + PF, respectively, comparing to very toxic (100%) raw textile wastewater. Thus, activated carbon adsorption was applied as an additional step to complete the treatment. After AC adsorption, the acute toxicity decreased to 10% and 0% using EC + F and EC + PF, respectively. The total operational costs, including chemical reagents, electrodes, energy consumption and sludge disposal, were of 1.65 USD/m3 and 2.3 USD/m3 for EC + F and EC + PF, respectively.
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14651. 题目: Impact of agricultural fertilization practices on organo-mineral associations in four long-term field experiments: Implications for soil C sequestration
文章编号: N18092202
期刊: Science of The Total Environment
作者: Yongli Wen, Wenjuan Liu, Wenbo Deng, Xinhua He, Guanghui Yu
更新时间: 2018-09-22
摘要: Soil organic carbon (SOC) associated with minerals is considered to be one of the most fundamental long-term SOC storage strategies, but little research has integrated the organo-mineral complexes regulated by long-term fertilization. Here, soil samples under three fertilization treatments (Control, no fertilization; NPK, chemical nitrogen, phosphorus and potassium fertilization; NPKM, NPK plus manure) from four 23–34 years long-term field experiment sites across China were examined. Chemical analyses indicated that vigorous iron (Fe) mobilization could be regulated by long-term fertilization regimes. Meanwhile, Fe K-edge X-ray absorption near-edge fine structure (XANES) demonstrated that compared to NPK treated soils, NPKM treated soils contained significantly higher concentration of poorly crystalline ferrihydrite. Results from both the Fourier transform infrared combined with two-dimensional correlation spectroscopy analyses (FTIR-2DCOS) and C 1 s X-ray photoelectron spectroscopy (XPS) revealed that aliphatic carbohydrate might play an important role in binding exogenous Fe(III) in all tested four soils. In addition, greater amounts of aromatic C (the most resistant soil C fraction) were under long-term treated NPKM than NPK soils. Furthermore, multiple regression analyses showed a significantly positive relationship between poorly crystalline Fe minerals and SOC or aromatic C. Such relationships indicated that aromatic functional groups had been attached to the poorly crystalline Fe minerals, which could also be protected from being transformed to the crystalline counterpart. In conclusion, results from our integrated spectroscopic analyses have evidenced greater improvement of both poorly crystalline Fe minerals and aromatic C in organically fertilized than in chemically fertilized soils.
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14652. 题目: Environmental availability of sulfamethoxazole and its acetylated metabolite added to soils via sludge compost or bovine manure
文章编号: N18092201
期刊: Science of The Total Environment
作者: Anaïs Goulas, Nicolas Sertillanges, Khaled Brimo, Patricia Garnier, Valérie Bergheaud, Valérie Dumény, Pierre Benoit, Claire-Sophie Haudin
更新时间: 2018-09-22
摘要: The fate of antibiotics and their metabolites in soils after application of organic waste depends on their environmental availability, which depends on the quality and biodegradability of the added exogenous organic matter (EOM). This study aimed at better understanding the fate of sulfamethoxazole (SMX) and N-acetyl-sulfamethoxazole (AcSMX) metabolite added to soils via sludge compost or cow manure application, during a 28-day incubation. Experimental results obtained for mineralized, extractable, and non-extractable fractions as well as EOM mineralization were used to couple SMX and AcSMX dynamics to the EOM evolution using the COP-Soil model. According to various mechanisms of extraction, CaCl2, EDTA and cyclodextrin solutions extracted contrasted available fractions (31–96% on day 0), resulting in different sets of parameter values in the model. CaCl2 extraction was the best method to assess the sulfonamide availability, leading to low relative root mean squared errors and best simulations of SMX and AcSMX dynamics. The decrease of SMX and AcSMX availability over time went with the formation of non-extractable residues, mostly of physicochemical origin. Using the COP-Soil model, the co-metabolism was assumed to be responsible for the formation of biogenic non-extractable residues and the low mineralization of SMX and AcSMX.
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14653. 题目: Blue carbon storage capacity of temperate eelgrass (Zostera marina) meadows
文章编号: N18092112
期刊: Global Biogeochemical Cycles
作者: Maria Emilia Röhr, Marianne Holmer, Julia K. Baum, Mats Björk, Diana Chin, Lia Chalifour, Stephanie Cimon, Mathieu Cusson, Martin Dahl, Diana Deyanova, J. Emmett Duffy, Johan S. Eklöf, Julie K. Geyer, John N. Griffin, Martin Gullström, Clara M. Hereu, Masakazu Hori, Kevin A. Hovel, A. Randall Hughes, Pablo Jorgensen, Stephanie Kiriakopolos, Per-Olav Moksnes, Masahiro Nakaoka, Mary I. O´Connor, Bradley Peterson, Katrin Reiss, Pamela L. Reynolds, Francesca Rossi, Jennifer Ruesink, Rui Santos, John J. Stachowicz, Fiona Tomas, Kun-Seop Lee, Richard K. F. Unsworth, Christoffer Boström
更新时间: 2018-09-21
摘要: Despite the importance of coastal ecosystems for the global carbon budgets, knowledge of their carbon storage capacity and the factors driving variability in storage capacity, is still limited. Here we provide an estimate on the magnitude and variability of carbon stocks within a widely distributed marine foundation species throughout its distribution area in temperate Northern hemisphere. We sampled 54 eelgrass (Zostera marina) meadows, spread across eight ocean margins and 36 degrees of latitude, to determine abiotic and biotic factors influencing organic carbon (Corg) stocks in Z. marina sediments. The Corg stocks (integrated over 25 cm depth) showed a large variability and ranged from 318 to 26523 g C m‐2 with an average of 2721 g C m‐2. The projected Corg stocks obtained by extrapolating over the top 1 m of sediment ranged between 23.1‐351.7 Mg C ha‐1 which is in line with estimates for other seagrasses and other blue carbon ecosystems. Most of the variation in Corg stocks was explained by five environmental variables (sediment mud content, dry density and degree of sorting, and salinity and water depth), while plant attributes such as biomass and shoot density were less important to Corg stocks. Carbon isotopic signatures indicated that at most sites

14654. 题目: Fire severity effects on soil carbon and nutrients and microbial processes in a Siberian larch forest
文章编号: N18092111
期刊: Global Change Biology
作者: Sarah M Ludwig, Heather D Alexander, Knut Kielland, Paul J Mann, Susan M Natali, Roger W Ruess
更新时间: 2018-09-21
摘要: Fire frequency and severity are increasing in tundra and boreal regions as climate warms, which can directly affect climate feedbacks by increasing carbon (C) emissions from combustion of the large soil C pool and indirectly via changes in vegetation, permafrost thaw, hydrology, and nutrient availability. To better understand the direct and indirect effects of changing fire regimes in northern ecosystems, we examined how differences in soil burn severity (i.e., extent of soil organic matter combustion) affect soil C, nitrogen (N), and phosphorus (P) availability and microbial processes over time. We created experimental burns of three fire severities (low, moderate, high) in a larch forest in the northeastern Siberian Arctic and analyzed soils at 1‐day, 8‐days, and 1‐year post‐fire. Labile dissolved C and N increased with increasing soil burn severity immediately (1‐day) post‐fire by up to an order of magnitude, but declined significantly 1‐week later; both variables were comparable or lower than unburned soils by 1‐year post‐fire. Soil burn severity had no effect on P in the organic layer, but P increased with increasing severity in mineral soil horizons. Most extracellular enzyme activities decreased by up to 70% with increasing soil burn severity. Increasing soil burn severity reduced soil respiration 1‐year post‐fire by 50%. However, increasing soil burn severity increased net N mineralization rates 1‐year post‐fire, which were 10‐fold higher in the highest burn severity. While fires of high severity consumed approximately five times more soil C than those of low severity, soil C pools will also be driven by indirect effects of fire on soil processes. Our data suggest that despite an initial increase in labile C and nutrients with soil burn severity, soil respiration and extracellular activities related to the turnover of organic matter were greatly reduced, which may mitigate future C losses following fire.

14655. 题目: Microbial decomposition processes and vulnerable arctic soil organic carbon in the 21st century
文章编号: N18092110
期刊: Biogeosciences
作者: Junrong Zha and Qianlai Zhuang
更新时间: 2018-09-21
摘要: Various levels of representations of biogeochemical processes in current biogeochemistry models contribute to a large uncertainty in carbon budget quantification. Here, we present an uncertainty analysis with a process-based biogeochemistry model, the Terrestrial Ecosystem Model (TEM), into which detailed microbial mechanisms were incorporated. Ensemble regional simulations with the new model (MIC-TEM) estimated that the carbon budget of the arctic ecosystems is 76.0±114.8PgC during the 20th century, i.e., −3.1±61.7PgC under the RCP 2.6 scenario and 94.7±46PgC under the RCP 8.5 scenario during the 21st century. Positive values indicate the regional carbon sink while negative values are a source to the atmosphere. Compared to the estimates using a simpler soil decomposition algorithm in TEM, the new model estimated that the arctic terrestrial ecosystems stored 12Pg less carbon over the 20th century, i.e., 19 and 30PgC less under the RCP 8.5 and RCP 2.6 scenarios, respectively, during the 21st century. When soil carbon within depths of 30, 100, and 300cm was considered as initial carbon in the 21st century simulations, the region was estimated to accumulate 65.4, 88.6, and 109.8PgC, respectively, under the RCP 8.5 scenario. In contrast, under the RCP 2.6 scenario, the region lost 0.7, 2.2, and 3PgC, respectively, to the atmosphere. We conclude that the future regional carbon budget evaluation largely depends on whether or not adequate microbial activities are represented in earth system models and on the sizes of soil carbon considered in model simulations.
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14656. 题目: Multiple sulphur isotope records tracking basinal and global processes in the 1.98 Ga Zaonega Formation, NW Russia
文章编号: N18092109
期刊: Chemical Geology
作者: K. Paiste, A. Lepland, A.L. Zerkle, K. Kirsimäe, G. Izon, N.K. Patel, F. McLean, T. Kreitsmann, K. Mänd, T.H. Bui, A.E. Romashkin, D.V. Rychanchik, A.R. Prave
更新时间: 2018-09-21
摘要: The exceptionally organic-rich rocks of the 1.98 Ga Zaonega Formation deposited in the Onega Basin, NW Russia, have refined our understanding of Earth System evolution during the Paleoproterozoic rise in atmospheric oxygen. These rocks were formed in vent- or seep-influenced settings contemporaneous with voluminous mafic volcanism and contain strongly 13C-depleted organic matter. Here we report new isotopic (δ34S, Δ33S, Δ36S, δ13Corg) and mineralogical, major element, total sulphur and organic carbon data for the upper part of the Zaonega Formation, which was deposited shortly after the termination of the Lomagundi-Jatuli positive carbon isotope excursion. The data were collected on a recently obtained 102 m drill-core section and show a δ13Corg shift from −38‰ to −25‰. Sedimentary sulphides have δ34S values typically between +15‰ and +25‰ reflecting closed-system sulphur isotope behaviour driven by high rates of microbial sulphate reduction, high sulphate demand, hydrothermal activity and hydrocarbon seepage. Four intervals record δ34S values that exceed +30‰. We interpret these unusually 34S-enriched sulphides to be a result of limited sulphate diffusion into pore waters due to changes in sedimentation and/or periods of basinal restriction. Additionally, there are four negative δ34S and positive Δ33S excursions that are interpreted to reflect changes in the open/closed-system behaviour of sulphate reduction or availability of reactive iron. Our findings highlight the influence of basinal processes in regulating sulphur isotope records and the need for care before interpreting such signals as reflecting global conditions.

14657. 题目: Soil physicochemical properties associated with quasi-circular vegetation patches in the Yellow River Delta, China
文章编号: N18092108
期刊: Geoderma
作者: Qingsheng Liu, Gaohuan Liu, Chong Huang, He Li
更新时间: 2018-09-21
摘要: In recent years, decreased runoff and sediment, intensified storm surge and seawater intrusion, urbanization, petroleum exploration, and production, and other factors have gradually deteriorated the unique wetland ecosystem in the Yellow River Delta (YRD). Although previous studies have analyzed the relationships between vegetation and soil properties at different scales, few studies have documented quasi-circular vegetation patches (QVPs) in the YRD, which appear to exhibit faster succession rates that make them ideal for studies on the relationships between vegetation and soil properties. Therefore, this study investigated differences in soil physicochemical properties at 0–20 cm depths between QVPs and inter-QVP bare soil areas, among QVPs, and among plant species communities. Additionally, spatial variations in soil physicochemical properties were explored in south-north and west-east transects across and within QVPs. The results showed that soils beneath QVPs had significant fertility island effects associated with soil organic matter (SOM) and total nitrogen (TN). Furthermore, these areas were richer in clay content, showed slightly higher pH values, and exhibited less available phosphorus (APH), available potassium (APO), total salt content, and silt content than those of bare soil areas. A multiple independent samples nonparametric Kruskal-Wallis H test detected significant differences in SOM, TN, APH, and pH among 18 QVPs, but no significant differences were found in APO, total salt content, sand, silt, and clay contents. Regardless of plant species, different plant species communities had significant effects on soil physicochemical properties. Particularly, soils underneath plant species communities with Tamarix chinensis were richer in SOM and TN, and they contained less APH, APO, and total salt content than those without T. chinensis. In each QVP, values of SOM and TN in soil samples along the patch perimeter were less than those of samples located midway toward the perimeter, and these values were less than those of samples centered in the patch. However, APO and total salt content values exhibited opposite changes from the perimeter to the center of the patch. The results also indicated significant differences in SOM, TN, APH, APO, and pH between south-north transect A and west-east transect B across QVPs, but no significant differences were found in total salt content, sand, silt, and clay contents. Therefore, the results of this study indicate that QVPs have significant effects on topsoil nutrients and salinity but little effects on soil texture. Furthermore, the occurrence and development of QVPs are associated with suitable soil conditions, including higher clay fractions and lower total salt content values.

14658. 题目: A concise review of biochar application to agricultural soils to improve soil conditions and fight pollution
文章编号: N18092107
期刊: Journal of Environmental Management
作者: Muhammad Shaaban, Lukas Van Zwieten, Saqib Bashir, Aneela Younas, Avelino Núñez-Delgado, Muhammad Afzal Chhajro, Kashif Ali Kubar, Umeed Ali, Muhammad Shoaib Rana, Mirza Abid Mehmood, Ronggui Hu
更新时间: 2018-09-21
摘要: Application of biochar to soil can play a significant role in the alteration of nutrients dynamics, soil contaminants as well as microbial functions. Therefore, strategic biochar application to soil may provide agronomic, environmental and economic benefits. Key environmental outcomes may include reduced availability of toxic metals and organic pollutants, reduced soil N losses and longer-term storage of carbon in soil. The use of biochar can certainly address key soil agronomic constraints to crop production including Al toxicity, low soil pH and may improve nutrient use efficiency. Biochar application has also demerits to soil properties and attention should be paid when using a specific biochar for a specific soil property improvement. This review provides a concise assessment and addresses impacts of biochar on soil properties.
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14659. 题目: Two novel decamethyl henicosanes (C31H64) identified in a Maoming Basin shale, China
文章编号: N18092106
期刊: Organic Geochemistry
作者: Jing Liao, Hong Lu, Qiao Feng, Youping Zhou, Quan Shi, Ping'an Peng, Guoying Sheng
更新时间: 2018-09-21
摘要: Two new C31 branched alkanes (botryococcanes) presumably produced by the B race of Botryococcus braunii were isolated and purified from the Maoming Basin shales using column chromatography and preparative gas chromatography and structurally characterized with HR-EI-MS and 1D and 2D NMR. Interpretation of their EI mass spectral and 1D and 2D NMR (HMBC and HSQC) data led to the firm assignments of the two alkanes as diastereoisomeric 2,3,6,7,10,12,15,16,19,20-decamethylhenicosanes (DMHs). The structural assignments were further confirmed by the close match of the measured 13C NMR chemical shifts with those predicted by Lindeman-Adams 13C chemical shift modeling. The skeletons of these two DMHs are virtually identical to that of the recently identified C33 botryococcane/botryococcanone in the same sample. It is proposed that these two DMHs share a precursor C33 botryococcene biochemically formed by condensing two farnesyl diphosphates involving an unusual cyclobutanation, a retro-Prins reaction and a tetramethylation. A photo-mediated geochemical oxidation of the double bond in the ethenyl group connected to the sole quaternary carbon C-10 is also proposed to be responsible for the formation of the co-occurring DMHs and C33 botryococcane/botryococcanone.

14660. 题目: Magnetic lignin-based carbon nanoparticles and the adsorption for removal of methyl orange
文章编号: N18092105
期刊: Colloids and Surfaces A: Physicochemical and Engineering Aspects
作者: Ying-zhi Ma, Da-feng Zheng, Zhen-ye Mo, Rui-jing Dong, Xue-qing Qiu
更新时间: 2018-09-21
摘要: In order to expand the application of lignin, magnetic lignin-based carbon nanoparticles (MLBCN) were synthesized using a precipitation-carbonization process and the structure was confirmed by FTIR, XRD, Raman, BET, SEM, DLS and VSM. The adsorption of MLBCN for methyl orange was consistent with the Langmuir model and pseudo-second-order model, showing monolayer adsorption, with a maximum adsorption capacity of 113.0 mg/g and chemisorption being the rate-controlling step. This process was exothermic and of entropy reduction, showing spontaneous below 35 °C. MLBCN could be used under near neutral conditions and easily regenerated. This study demonstrates that MLBCN is promising as an efficient, sustainable absorbent.
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