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28561. 题目: DOM from mariculture ponds exhibits higher reactivity on photodegradation of sulfonamide antibiotics than from offshore seawaters
文章编号: N18071808
期刊: Water Research
作者: Jieqiong Wang, Jingwen Chen, Xianliang Qiao, Yan Wang, Xiyun Cai, Chengzhi Zhou, Yaoling Zhang, Guanghui Ding
更新时间: 2018-07-18
摘要: Mariculture activities and river inputs lead to coastal seawaters with DOM levels that are comparable to or even higher than those in terrestrial water bodies. However, effects of seawater DOM, and especially of DOM occurring in areas impacted by mariculture, on photodegradation of organic micropollutants, are largely unknown. In this study, simulated sunlight irradiation experiments were performed to probe the effects of DOM extracted from mariculture impacted seawaters and from offshore areas, on photodegradation of three sulfonamide antibiotics (SAs). Results show that the SAs are transformed mainly by indirect photodegradation induced by triplet excited DOM (3DOM*). Compared with DOM from the more pristine coastal waters, the DOM from mariculture impacted areas undergoes less photobleaching, contains higher percentage of humic-like materials and higher proportions of aromatic and carbonyl structures. Thus, the DOM from mariculture areas exhibits higher rates of light absorption, higher formation quantum yields of 3DOM*, higher 3DOM* steady-state concentrations and higher reactivity on photodegradation of the SAs. Photochemistry of the seawater DOM is different from that reported for freshwater lake DOM. This study highlights the importance of probing the effects of DOM from coastal seawaters on photodegradation of organic micropollutants since coastal seawaters are sinks of many aquatic pollutants.

28562. 题目: Leachate from fine root litter is more acidic than leaf litter leachate: A 2.5-year laboratory incubation
文章编号: N18071807
期刊: Science of The Total Environment
作者: Toko Tanikawa, Saori Fujii, Lijuan Sun, Yasuhiro Hirano, Yosuke Matsuda, Kouhei Miyatani, Ryuusei Doi, Takeo Mizoguchi, Nagamitsu Maie
更新时间: 2018-07-18
摘要: Some tree species increase fine root production under soil acidification, thus changing the balance of litter input from leaves and roots. Litter leaches a significant amount of acidic materials during its decomposition, which might facilitate soil acidification. In this context, we focused on dissolved organic matter (DOM) as the major component of acidic materials. We hypothesized that both the quality and quantity of DOM, which control its function (i.e., proton supply), differ between leaf and root litter. To test this hypothesis, we conducted a 2.5-year laboratory incubation experiment using fresh fine roots and fresh green leaves as litter of two coniferous species (Cryptomeria japonica and Chamaecyparis obtusa) and investigated the leachate pH and DOM composition based on the optical properties. After the early stage of decomposition when flash leaching of DOM converged, the amount of dissolved organic carbon (DOC) leached from roots increased again and leachate pH declined. In contrast, DOC concentrations continued to decrease in leaf leachates during the incubation period, and the pH decrease was not as striking as that of root leachates. Optical properties (ultraviolet visible absorption and fluorescence) of DOM revealed that humic-like substances in DOM played a central role in the acidic pH of root leachates. The total amount of protons released from roots of C. japonica and C. obtusa is about 13 and 18 times higher, respectively, than that from leaves. These results imply that the increase of fine root biomass may induce a positive plant–soil feedback in acidic soils, affecting soil biogeochemical functions of terrestrial ecosystems.

28563. 题目: Retention and remobilization mechanisms of environmentally aged silver nanoparticles in an artificial riverbank filtration system
文章编号: N18071806
期刊: Science of The Total Environment
作者: Laura Degenkolb, George Metreveli, Allan Philippe, Anja Brandt, Kerstin Leopold, Lisa Zehlike, Hans-J?rg Vogel, Gabriele E. Schaumann, Thomas Baumann, Martin Kaupenjohann, Friederike Lang, Samuel Kumahor, Sondra Klitzke
更新时间: 2018-07-18
摘要: Riverbank filtration systems are important structures that ensure the cleaning of infiltrating surface water for drinking water production. In our study, we investigated the potential risk for a breakthrough of environmentally aged silver nanoparticles (Ag NP) through these systems. Additionally, we identified factors leading to the remobilization of Ag NP accumulated in surficial sediment layers in order to gain insights into remobilization mechanisms. We conducted column experiments with Ag NP in an outdoor pilot plant consisting of water-saturated sediment columns mimicking a riverbank filtration system. The NP had previously been aged in river water, soil extract, and ultrapure water, respectively. We investigated the depth-dependent breakthrough and retention of NP. In subsequent batch experiments, we studied the processes responsible for a remobilization of Ag NP retained in the upper 10 cm of the sediments, induced by ionic strength reduction, natural organic matter (NOM), and mechanical forces. We determined the amount of remobilized Ag by ICP-MS and differentiated between particulate and ionic Ag after remobilization using GFAAS. The presence of Ag-containing heteroaggregates was investigated by combining filtration with single-particle ICP-MS. Our study indicates that the breakthrough potential of Ag NP in riverbank filtration systems is generally low, but the aging in soil increases their mobility. Remobilization processes are associated to co-mobilization with natural colloids.

28564. 题目: Comparison of n-alkane molecular, carbon and hydrogen isotope compositions of different types of plants in the Dajiuhu peatland, central China
文章编号: N18071805
期刊: Organic Geochemistry
作者: Bingyan Zhao, Yiming Zhang, Xianyu Huang, Ruya Qiu, Zhiqi Zhang, Philip A. Meyers
更新时间: 2018-07-18
摘要: Long chain n-alkanes preserved in peat deposits have been widely used to reconstruct paleoenvironmental and paleoecological changes. However, our knowledge of how the leaf wax molecular and isotopic compositions of peat sequences might respond to changes in plant communities is limited. This study investigates the n-alkane molecular, carbon and hydrogen isotopic compositions of plant species collected from the Dajiuhu peatland, central China. The results show that forb and graminoid plants growing in peatlands have a relatively higher carbon preference index of long-chain n-alkanes than shrubs, ferns and aquatic plants. The δ13C values of individual n-alkanes generally decrease with increasing chain lengths, and different plant groups have similar δ13C values of C31 and C33n-alkanes. An exception is Sphagnum, which has more negative δ13C values of C23 and C25 than those of its longer chain length homologues. Relative to peat pore water δD values in different seasons and different peat depths, the Dajiuhu plants normally exhibit relatively large hydrogen isotope fractionations, and the fractionations gradually increase from graminoid to forb to shrub. Taken together, these results highlight the influence of different kinds of vegetation on the collective molecular and isotopic ratios of n-alkanes in peat deposits.

28565. 题目: Mechanism of oxidation and catalysis of organic matter abiotic humification in the presence of MnO2
文章编号: N18071804
期刊: Journal of Environmental Sciences
作者: Yingchao Zhang, Dongbei Yue, Xu Wang, Wenfang Song
更新时间: 2018-07-18
摘要: Humification plays a critical role in the environmental fate of organic wastes, and MnO2 holds great promise for enhancing this reaction. However, the effects of MnO2 on the enhancement of the humification reaction remain ambiguous. To better reveal the mechanism by which MnO2 enhances the reaction and investigate the fate of the humification products, abiotic humification experiments were performed using increasing concentrations of dissolved organic matter (DOM) to a fixed amount of MnO2. DOM was represented by model humic precursors consisting of catechol, glucose and glycine. The results indicate that the reduction of MnO2 played a dominant role in the formation of fulvic-like acids (FLAs), and the subsequent reduction products, MnOOH and Mn(II), acted as catalysts in the formation of humic-like acids (HLAs). Moreover, CO2 release occurred during the formation of FLAs, and a strong linear correlation between CO2 release and the formation of FLAs was observed (p < 0.01), where 0.73–1.87 mg of CO2 was released per mg dissolved organic carbon (DOC) FLAs. Furthermore, the concentration of MnO2 had a pronounced influence on the product behavior, where a lower MnO2 concentration decreased the quantity of FLAs produced.

28566. 题目: Composition and bioavailability of dissolved organic matter in different water masses of the East China sea
文章编号: N18071803
期刊: Estuarine, Coastal and Shelf Science
作者: Jin-qiang Guo, Sheng-kang Liang, Xiao-jiao Li, Wei Li, Yun-fei Wang, Rong-guo Su
更新时间: 2018-07-18
摘要: The degradation of dissolved organic matter (DOM) is affected by ocean currents, but this influence is poorly understood in the East China Sea (ECS), a dynamic shallow continental shelf characterized by several discrete water masses. This study investigates dissolved organic carbon (DOC), nitrogen (DON) and total dissolved amino acids (TDAA) in different water masses of the ECS. Bioassay experiments were also conducted to determine the labile fraction of DOM. Carbon-normalized yields of TDAA [TDAA (%DOC)] as well as the degradation index (DI) was used to investigate the diagenetic state of organic matter in different water masses. Generally, DOM concentration decreased from the Coastal Current Water (CCW), to the Shelf Mixed Water (SMW), to the Taiwan Warm Current Water (TWCW), and to the Kuroshio Current Water (KCW). DOM in CCW is relatively labile due to inputs from phytoplankton production, while that in the TWCW exhibits low bioavailability, which may be related to nutrient limitation leading to low productivity. The long residence time of the KCW resulted in a high degree of biodegradation associated with nutrient regeneration. Intrusion of nutrient-rich KCW may contribute to the high primary productivity in shelf water, while complex hydrodynamic processes and stratification may control DOM availability in SMW.

28567. 题目: Improved sludge dewaterability using persulfate activated with humic acid supported nanoscale zero-valent iron : Effect on sludge characteristics and reaction mechanisms
文章编号: N18071802
期刊: Environmental Science: Water Research & Technology
作者: Hao Li, Lei Song, Baohong Han, Hongwei Song
更新时间: 2018-07-18
摘要: n this study, nanoscale zero-valent iron (nZVI) supported on humic acid (HA) as a novle nanocomposite (nZVI/HA) was synthesized and characterized by field emission scanning electron microscope (FE-SEM), energy dispersive spectrometry (EDS), Fourier transform infrared (FTIR), and Brunauer–Emmett–Teller method. The nZVI/HA nanocomposite was used as persulfate (PS) activator to enhance sludge dewatering, and the specific resistance to filterability (SRF) of sludge decreased from 2.75×1013 m/kg to 0.217×1013 m/kg after conditioning. Subsequently, variation in extracellular polymeric substances (EPS) under chemical conditioning was investigated concretely to reveal the reaction mechanisms. Analysis of three-dimensional excitation emission matrix (3D-EEM), the reduction of aromatic protein and tryptophan-like protein content in tight-bound extracellular polymers substances (TB-EPS) is conducive for enhancing sludge dewateribility. In addition, the introduction of HA particles effectively decreased sludge compressibility relative to that of raw sludge by forming skeleton structures. The observed sludge microstructure properties clearly indicated that treated sludge floc induced the formation of additional pore structures and water channels.

28568. 题目: Microbial lipid production and organic matters removal from cellulosic ethanol wastewater through coupling Oleaginous yeasts and activated sludge biological method
文章编号: N18071801
期刊: Bioresource Technology
作者: Xueling Zhang, Meng Liu, Xu Zhang, Tianwei Tan
更新时间: 2018-07-18
摘要: In this paper, a novel strategy for lipid production through coupling oleaginous yeasts and activated sludge biological methods by cultivation of Rhodotorula glutinis in cellulosic ethanol wastewater was studied. Under optimal conditions in wastewater medium (dilution ratio of 1:2 and glucose supplement of 40 g/L), the maximum biomass and lipid content as well as the lipid yield reached 11.31 g/L, 18.35% and 2.08 g/L, with the associated removal rates of COD, TOC, NH4+-N, TN and TP reaching 83.15%, 81.81%, 85.49%, 70.52% and 67.46%, respectively. Cellulosic ethanol wastewater treated by the anaerobic-aerobic biological process resulted in removal of COD, NH4+-N, TP and TN reaching 67.55%, 94.17%, 90.16% and 48.89%, respectively. The reused water was used to dilute medium of R. glutinis for microbial lipid production reaching 2.38 g/L and caused positive effects on the accumulation of biomass and lipid.

28569. 题目: Determining phytolith-occluded organic carbon sequestration using an upgraded optimized extraction method: indicating for a missing carbon pool
文章编号: N18071701
期刊: Environmental Science and Pollution Research
作者: Ning Han, Yufei Yang Email, Yang Gao, Zhuo Hao, Jing Tian, Tiantian Yang, Xianwei Song
更新时间: 2018-07-17
摘要: Phytolith-occluded organic carbon (PhytOC) is considered one of the most promising terrestrial carbon (C) sinks. Different methods are used for phytolith extraction from wet-ashing techniques and the subsequent determination of PhytOC content from soil. This is in order to optimize the wet-ashing techniques and to improve estimation accuracy of C sequestration potential of phytoliths from soil. Results show that the organic matter removal and carbonate removal protocol, applying sonication, has a significant effect on phytolith extraction. Namely, the sequential removal of first organic matter and then carbonates applied to such methods could eliminate greater than 17.14, 46.68, and 26.17% extraneous material compared to other methods. Moreover, phytoliths extracted using methods that apply sonication eliminated 7.49, 42.70, and 17.57% more extraneous material than methods that did not. Additionally, the procedure associated with the second oxidation step significantly influenced the determination of PhytOC content, that is, 29.34, 33.75, 26.41, and 64.64% of excess organic C were oxidized during this step. The upgraded optimal method we recommend for phytolith extraction in association with wet-ashing techniques and the subsequent determination of PhytOC content is therefore to first apply sonication, then the second oxidation step, and finally the removal of organic matter. Using this optimal upgraded method, we estimated the C sequestration potential of phytoliths from the soil of slash pine in China at 0.51 Mt. C. Furthermore, using this upgraded optimal method increased the precision of the carbon sequestration potential of phytoliths from soil by up to 63.83%.

28570. 题目: Plant litter quality affects the accumulation rate, composition, and stability of mineral-associated soil organic matter
文章编号: N18071507
期刊: Soil Biology and Biochemistry
作者: S. Carolina Córdova, Dan C. Olk, Ranae N. Dietzel, Kevin E. Mueller, Sotirios V. Archontouilis, Michael J. Castellano
更新时间: 2018-07-15
摘要: Mineral-associated organic matter (MAOM) is a relatively large and stable fraction of soil organic matter (SOM). Plant litters with high rates of mineralization (high quality litters) are hypothesized to promote the accumulation of MAOM with greater efficiency than plant litters with low rates of mineralization (low-quality litters) because litters with high rates of mineralization maximize the synthesis of microbial products and most MAOM is microbial-derived. However, the effect of litter quality on MAOM is inconsistent. We conducted four repeated short-term incubations (46-d each) of four plant litters (alfalfa, oats, maize and soybean) in two low-carbon subsoils (sandy loam and silty loam) with and without nutrient addition. Our short-term incubations focused on the initial stage of litter decomposition during the time when litter quality has a measureable effect on mineralization rates. Plant litter quality had a much greater effect on litter-C mineralization rate and MAOM-C accumulation than did soil type or nutrient addition. Soils amended with high-quality oat and alfalfa litters had greater MAOM-C accumulation than soils amended with low-quality maize and soybean litters. However, soils amended with high-quality litters also had greater litter-C mineralization than soils amended with low-quality litters. As a result, the accumulation of MAOM-C per unit of litter-C mineralization was lower in soils amended with high-vs. low-quality litters (0.65 vs. 1.39 g MAOM-C accumulated g-1 C mineralized). Cellulose and hemicelluose indices of accumulated MAOM were greater for maize and soybean than oats and alfalfa, however, most carbohydrates in MAOM were plant-derived regardless of litter quality. At the end of the incubations, more of the accumulated MAOM-N was potentially mineralizable in soils amended with high quality litters. Nevertheless, most of the litter-C remained as residual litter; just 12% was mineralized to CO2 and 13% was transferred to MAOM. Our results demonstrate several unexpected effects of litter quality on MAOM stabilization including the direct stabilization of plant-derived carbohydrates.

28571. 题目: Plant rhizosphere oxidation reduces methane production and emission in rewetted peatlands
文章编号: N18071506
期刊: Soil Biology and Biochemistry
作者: Svenja Agethen, Michael Sander, Carolin Waldemer, Klaus-Holger Knorr
更新时间: 2018-07-15
摘要: The global loss of peatlands, by drainage or peat extraction, has encouraged measures to restore these ecosystems and their function as carbon sinks. However, there is a potential of high emissions of the potent greenhouse gas CH4 from restored peatlands. Vascular plants, which often dominate restored sites, play a key role in determining the amount of emitted CH4: The plants can either fuel methanogenesis by supplying labile carbon or attenuate methanogenesis by transferring oxygen into the rhizosphere. To quantify the net effect of these counteracting processes, we tested in a two-pronged approach CH4 production, emission, and the underlying processes in (1.) monoliths of three different restored cutover peatlands and in (2.) mesocosms with Eriophorum vaginatum, E. angustifolium and Juncus effusus versus controls with Sphagna and bare peat. Despite waterlogged, and thus persisting anoxic conditions, concentrations of dissolved CH4 remained close to zero in all tested monoliths. We ascribe this finding to two factors: The poor decomposability of the peat material, as determined in anoxic incubations, and the availability of alternative electron acceptors that sustained anaerobic respiration and competitively suppressed methanogenesis. While inorganic electron acceptor pools were small and rapidly diminished, dissolved organic matter provided constant electron acceptor capacity, indicating that reducible moieties in the organic matter were continuously re-oxidized in the rhizosphere of all tested vascular plant species. This continuous re-oxidation of the dissolved organic matter correlated with plant growth rates (R2 = 0.6–0.8), suggesting that supply of oxygen through the aerenchyma of plant roots regenerated electron acceptor capacity in the rhizosphere. Vascular plants may have differential effects on the net ecosystem exchange, however, our findings suggest that CH4 concentrations and emissions may remain low in restored cutover peatlands for months to years. Thus, waterlogging and vascular plant cover of degraded cutover peatlands does not necessarily create hot-spots of CH4 emissions.

28572. 题目: Influence of ancient anthropogenic activities on the mangrove soil microbiome
文章编号: N18071505
期刊: Science of The Total Environment
作者: Luciano F. Huergo, Daniel V. Rissi, Andressa S. Elias, Maria V. Gon?alves, Marcos V. Gernet, Flávio Barreto, Gilson W. Dahmer, Rodrigo A. Reis, Fábio O. Pedrosa, Emanuel M. Souza, Rose A. Monteiro, Valter A. Baura, Eduardo Balsanelli, Leonardo M. Cruz
更新时间: 2018-07-15
摘要: Mangroves are highly productive ecosystems located at the transition between the terrestrial and marine environments. Mangroves play an important role in carbon storage, nutrient cycling and support for the marine food web. Mangrove soils are formed by fine particles rich in organic carbon and are subject to constant fluctuations in oxygen, salinity and nutrient availability due to fresh water flux and tidal variations. Microbes play an important role in nutrient cycling in mangrove soils; however, studies on the mangrove soil microbiome are scarce. Here we compare the microbiome of pristine mangrove soil located in an environmentally protected area in Guaratuba, Southern Brazil, with the microbiome of mangrove soil affected by the presence of carbonaceaous debris eroding from an archeological site known as Sambaqui. We show that although the Sambaqui site has a major effect on soil chemistry, increasing the soil pH by 2.6 units, only minor changes in the soil microbiome were detected indicating resilience of the microbial community to pH variations. The high alpha diversity indexes and predicted metabolic potential suggest that the mangrove soil microbiome not only provides important ecological services but also may host a broad range of microbes and genes of biotechnological interest.

28573. 题目: Probing algogenic organic matter (AOM) by size-exclusion chromatography to predict AOM-derived disinfection by-product formation
文章编号: N18071504
期刊: Science of The Total Environment
作者: Lap-Cuong Hua, Jr-Lin Lin, Shu-Ju Chao, Chihpin Huang
更新时间: 2018-07-15
摘要: High-performance size exclusion chromatography (HPSEC) coupled with peak-fitting technique was used to probe molecular weight (MW) properties of algogenic organic matter (AOM). The qualitative and quantitative MW information derived was used to predict AOM-derived disinfection by-product (DBP) formation. We resolved overlapping HPSEC chromatograms of all AOM samples into six major peaks with R2 > 0.996. This study gave significant insight into the HPSEC profiles of AOM, in which resolved peaks A and B (biopolymers) and peak C (humic substances) showed a strong correlation with the formation of carbonaceous-DBPs (C-DBPs). This likely resulted from the abundance of aromatic structures and conjugated CC double bonds in their chemical nature. Our results also indicated the importance of algal cells, including intra-cellular and cell-bound organic matter, over extra-cellular organic matter as precursors to C-DBP formation. The application of the information extracted from HPSEC profiles associated with the fluorescent components of AOM showed great improvements in the predictability of THMs, HAAs, and C-DBPs with R2 > 0.7 and p < 0.05. The outcome of this study will significantly benefit effective control of AOM-derived DBP formation by the chlorination of eutrophic waters.

28574. 题目: Effects of increasing nutrient disturbances on phytoplankton community structure and biodiversity in two tropical seas
文章编号: N18071503
期刊: Marine Pollution Bulletin
作者: Yuping Zhou, Bo Hu, Weihong Zhao, Dongyang Cui, Liju Tan, Jiangtao Wang
更新时间: 2018-07-15
摘要: Statistical analysis of rainfall data from 2005 to 2015 showed that atmospheric deposition supplied large amount of dissolved inorganic nitrogen (38–155 mg·m-2·month-1) in N-deficient South China Sea and Eastern Indian Ocean. To understand marine ecosystem responses to increasing nutrient disturbances, we implemented field mesocosm experiments to study phytoplankton community structure and biodiversity responses to nutrient treatments with nitrate, phosphate and iron across tropical seas. Our results showed that DIN supply would change phytoplankton community structure and stimulated the regime shift from cyanobacteria to diatoms (relative dominance R > 0). Phytoplankton communities were dominated by diatoms (relative abundance >50%) accompanied by high chlorophyll a content with 1.58–39.27 μg·L-1 in DIN-added cultures, whereas cyanobacteria dominated communities (relative abundance >60%) with low biomass of 0.12–0.18 μg·L-1 in undisturbed cultures. Simultaneously increased DIN loading from atmospheric deposition would decrease ecological diversity of tropical seas owing to species competition and succession (Shannon diversity H′ decreased to <1).

28575. 题目: Unregulated disinfection By-products in drinking water in Quebec: A meta analysis
文章编号: N18071502
期刊: Journal of Environmental Management
作者: Gyan Chhipi-Shrestha, Manuel Rodriguez, Rehan Sadiq
更新时间: 2018-07-15
摘要: Disinfection by-products (DBPs) are formed primarily by the reaction of natural organic matter and disinfectants. DBPs that are not regulated are referred to as unregulated DBPs (U-DBPs) and they are in majority in total DBPs. U-DBPs can be more toxic than regulated DBPs. U-DBPs such as haloacetonitriles (HANs), haloacetonitriles (HKs) and halonitromethanes (HNMs) are widely present in drinking water supplies in different regions of the world. This study investigated the occurrence of U-DBPs and their variability in drinking water in the Province of Quebec (Canada), using the water quality database of 40 municipal water systems generated by our research group. The concentrations of HANs, HKs, and their compounds, including chloropicrin (CPK), were highly variable in different water systems in Quebec. The concentration range of these U-DBPs is in line with drinking water concentration ranges in different regions of the world. Factors such as system size, water source, season, pH, total organic carbon content, free residual chlorine and disinfectant types cause significant variations in the concentrations of HANs, HKs and their constituent compounds, including CPK, in drinking water in Quebec. This information is valuable for decision making concerning source water selection, water distribution planning, water treatment plant design including disinfection, and overall drinking water quality management related to U-DBPs. Moreover, U-DBPs and regulated DBPs are strongly correlated, although the degree of correlation can vary with water source, system size and season, indicating that regulated DBPs can be used as surrogates of U-DBPs.

28576. 题目: Effects of soil components and solution inorganic cations on interactions of imidazolium-based ionic liquid with soils
文章编号: N18071501
期刊: Journal of Environmental Management
作者: Qiuci Miao, Erping Bi
更新时间: 2018-07-15
摘要: Effects of alkyl chain length of ionic liquid (IL), soil components and solution inorganic cations on a selected IL (1-methyl-3-octylimidazolium chloride, [OMIM]Cl) interaction with Chinese soils were investigated using batch sorption experiments. The results indicated that sorption energy was mainly controlled by chain length of [OMIM]Cl and contents of soil organic matter (SOM). [OMIM]Cl sorption on soils was mainly controlled by cation exchange process. Contributions of SOM and clay minerals (CMs) to [OMIM]Cl sorption were 7.3%–53.8% and 46.2%–92.7%, respectively. SOM possessed higher energy cation-exchange binding sites than CMs. To predict the sorption of [OMIM]Cl on soils, a model for the relationship between sorption coefficient (Kd) and cation exchange capacity (CEC) from soil components (SOM and CMs, i.e., CECSOM and CECCMs) as well as solution concentration (Ce) was established: LogKd = Log(1.67*CECSOM + 3.22*CECCMs) - 0.58LogCe. This model could provide a good prediction for sorption coefficients and the prediction errors were within 0.48 log unit. Competitive effects caused by inorganic cations followed the order of Ca2+ = Mg2+ > K+ > Na+. Concentrations and valence of coexisting ions both affect their competitive capability on [OMIM]Cl sorption. The finding of this study provided valuable information for evaluating the fate of [OMIM]Cl in soils.

28577. 题目: Impacts of soil abiotic attributes on Fusarium wilt, focusing on bananas
文章编号: N18071403
期刊: Applied Soil Ecology
作者: Ryan Orr, Paul N. Nelson
更新时间: 2018-07-14
摘要: Production of many crops, including bananas, is threatened worldwide by the spread of pathogenic strains of Fusarium oxysporum, the causal agent of Fusarium wilt. Severity of the disease is related to soil biotic and abiotic attributes, which influence the plant, the pathogen and the other soil organisms. Across a variety of crops, soil temperature, redox potential, and extractable iron and manganese contents are generally positively correlated with disease severity, whereas pH, nitrate:ammonium ratio, organic matter content and extractable calcium, zinc, silicon, potassium, phosphorus and boron contents are negatively correlated, but less consensus exists for bananas. There are numerous incompletely understood interactions between soil abiotic attributes and disease severity, including those between pH- and redox-controlled micronutrient availability, buffering by organic matter and clay, and effects of nutrients on plant defence mechanisms. Though not all soil attributes can be managed, pH, organic matter content and availability of nutrients show promise for manipulation to reduce disease severity and mitigate risk.

28578. 题目: Root litter decomposition slows with soil depth
文章编号: N18071402
期刊: Soil Biology and Biochemistry
作者: Caitlin E. Hicks Pries, Benjamin N. Sulman, Corinna West, Caitlin O'Neill, Erik Poppleton, Rachel C. Porras, Cristina Castanha, Biao Zhu, Daniel B. Wiedemeier, Margaret S. Torn
更新时间: 2018-07-14
摘要: Even though over half of the world's soil organic carbon (SOC) is stored in subsoils (>20 cm deep), and the old ages of subsoil OC indicate its cycling differs from surface SOC, there are few studies examining in situ decomposition processes in deep soils. Here, we added 13C-labeled fine roots to 15, 55, and 95 cm depths of a well-characterized coniferous forest Alfisol and monitored the amount of root-derived C remaining over 6, 12, and 30 months. We recovered the root-derived C in microbial phospholipid fatty acids (PLFAs) after 6 months and in coarse (>2 mm) particulate, fine (<2 mm) particulate, and dense, mineral-associated pools after 6, 12, and 30 months. Overall, root decomposition in the first 6 months was similar among all depths but significantly diverged at 30 months with faster decomposition at 15 cm than at 95 cm. There were more fungal and Gram negative-associated PLFAs at 15 cm than at 95 cm, and 13C analysis revealed those microbial groups preferred the added root carbon to native SOC. Mineral-associations were not the cause of slower decomposition at depth because similar amounts of applied root C was recovered in the dense fraction at all depths. The largest difference among depths was in the amount of root C recovered in the coarse particulate fraction, which was greater at 95 cm (50%) than at 15 cm (15%). Slower decomposition of the particulate pool at depth likely contributed to the increase in C:N ratios and depletion of δ13C values below 60 cm depth in our soil profiles. Simulations of these soils using the CORPSE model, which incorporates microbial priming effects and mineral stabilization of SOC, reproduced patterns of particulate and mineral-associated SOC over both time and depth and suggested that a lack of priming by root exudates at depth could account for the slower decomposition rate of particulate root material. Decomposition of deep particulate SOC may increase if root exudation or dissolved OC transport to depth increases.

28579. 题目: Organic carbon content and humus composition after application aluminum sulfate and rice straw to soda saline-alkaline soil
文章编号: N18071401
期刊: Environmental Science and Pollution Research
作者: Xingmin Zhao, Menglong Zhu, Xinxin Guo, Hongbin Wang, Biao Sui, Lanpo Zhao
更新时间: 2018-07-14
摘要: The soil organic carbon accumulation in soda saline-alkaline soil and the humus composition changes with application of aluminum sulfate and rice straw were investigated by the controlled simulative experiments in laboratory. For evaluating the amelioration effect, organic carbon content and humus composition in soda saline-alkaline soil were investigated with different application amounts of rice straw and aluminum sulfate. Potassium dichromate oxidation titration (exogenous heat) method and Kumada method were used to analyze the contents of organic carbon and humus composition, respectively. The transformation of soil organic matter in the saline-alkali soil during the amelioration has been clarified in this paper. The results demonstrated that the contents of soil organic carbon were significantly increased (13–92%) with different application amounts of rice straw and aluminum sulfate. The contents of free fraction and combined fraction of humus and their compositions (humic acid and fulvic acid) were increased with different application amounts of rice straw. The free fraction of humus was increased more dramatically. Due to aluminum sulfate application, free fraction of humus and humic acid (HA) was transformed to combined fraction partially. Free HA was changed to be P type with rice straw application. With aluminum sulfate application, free form of HA was changed from type P to type Rp. For rice straw application, combined HA only was transferred within the area of type A. Aluminum sulfate addition had no significant effect on the type of combined form of HA. With the same amount of rice straw application, the contents of soil organic carbon were increased by increasing the amount of aluminum sulfate application. Both rice straw and aluminum sulfate applications could reduce the humification degree of free and combined fraction of HA. According to the types of HA, it could be concluded that humus became younger and renewed due to the application of rice straw and aluminum sulfate.

28580. 题目: Contrasting Fe speciation in two humid forest soils: Insight into organomineral associations in redox-active environments
文章编号: N18071302
期刊: Geochimica et Cosmochimica Acta
作者: Elizabeth K. Coward, Aaron Thompson, Alain F. Plante
更新时间: 2018-07-13
摘要: While the contribution of iron (Fe)-bearing minerals to organic carbon (C) stabilization in terrestrial systems is well-described, the influence of Fe solid-phase speciation on organomineral associations is unclear in highly-dynamic, oxidation-reduction (redox)-active soils. In humid tropic forest soils, fluctuations in redox state accelerate weathering of Fe-bearing mineral phases, producing a spectrum of mineral sizes and bonding environments available for C stabilization, and confounding our understanding of C stability. Characterizing these Fe-bearing phases can help us understand the response of redox-active soil systems to climatic changes that may alter Fe mineral crystallinity and solubility, for instance changes in precipitation intensity, storm event frequency and temperature. Leveraging inorganic selective dissolution techniques, 57Fe M ssbauer spectroscopy (MBS), specific surface area (SSA) analyses and X-ray diffraction (XRD), we investigated mineral speciation in surface soils of contrasting lithologies from the Luquillo Critical Zone Observatory (LCZO), Puerto Rico. The LCZO provides a model investigatory framework in which high C inputs to surface horizons by similar vegetation, topography and climatic forcings are intercepted by highly-weathered, volcaniclastic Oxisols or quartz diorite-derived Inceptisols, producing a gradient of Fe content and speciation. Strong correlations observed between Fe concentrations and extraction-induced changes in SSA indicated target Fe phases contribute substantially to SSA of the bulk mineral matrix. MBS analysis of untreated soils reveal both Oxisol and Inceptisol soils are largely composed of FeIII-oxyhydroxides, accompanied by substantial FeII and silicate FeIII contributions in Inceptisol soils. FeIII-oxyhydroxides in the Oxisol soils were largely short-range-ordered (SRO), and notably, a fraction of particularly low-crystallinity FeIII-oxyhydroxide mineral phases in these soils appear protected against harsh reductive dissolution, whereas the overall higher crystallinity Fe phases in the Inceptisol soils, do not. These findings suggest that some high-SSA, SRO FeIII phases, which likely also have high C sorption capacities, may be immobilized against reduction in these Oxisol soils. Consequently, C associated with these FeIII phases may be preferentially stabilized in Oxisol soils, potentially driving disparate C mineralization and CO2 production rates across contrasting lithologies.