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23501. 题目: Evolution of Dissolved Organic Matter along a Septic System Plume: Evidence of Sustained Biogeochemical Activity in the Groundwater Zone
文章编号: N19051110
期刊: Journal of Geophysical Research: Biogeosciences
作者: P.J.K. Aukes, S.L. Schiff, W.D. Robertson
更新时间: 2019-05-11
摘要: Dissolved organic matter (DOM) is an important energy source for biogeochemical reactions. However, DOM is often assumed to be recalcitrant in the groundwater zone due to extensive microbial processing in the overlying soil zone and long groundwater residence times. Consequently, further heterotrophic microbial processes proceed at inherently low rates. Septic systems provide an ideal opportunity to study the evolution of groundwater DOM due to the development of confined and easily identifiable plumes of known age. Here we use measures of DOM composition (size‐exclusion liquid chromatography, ultraviolet‐absorbance, and C:N) to quantify DOM evolution along an exceptionally well‐characterized septic‐impacted groundwater plume. Elevated concentrations (5 to 8 mg C/L) close to the tile bed decrease to values below 2 mg C/L with lower UV‐absorbing components normalized to overall DOM concentration (SUVA) along the six‐year old plume flow path. The humic substance fraction (HSF) comprises the largest percentage of DOM and decreases in concentration along the septic plume. HSF properties also change with travel time becoming lower in molecular weight, SUVA, and C:N. Denitrification continues along the length of the plume concomitant with changes in DOM and HSF composition. Thus HSF, typically considered recalcitrant in subsurface environments, is actively cycled by microorganisms on multi‐year time frames in accordance with the recent paradigm shift for soil organic matter evolution. Lastly, measures of DOM composition indicate changes in DOM that are not evident from measures of concentration alone.

23502. 题目: Interactive effect of nitrogen addition and throughfall reduction decreases soil aggregate stability through reducing biological binding agents
文章编号: N19051109
期刊: Forest Ecology and Management
作者: Zhijie Chen, Xueya Zhou, Shicong Geng, Yuan Miao, Yanhong Cao, Zheng Chen, Junhui Zhang, Shijie Han
更新时间: 2019-05-11
摘要: Soil aggregate stability is an important property for soil carbon sequestration and many other soil functions, but the co-impacts on soil aggregates from nitrogen (N) deposition and precipitation change (two important features of global climate changes) remain unknown. In this study, N addition and throughfall reduction were implemented in a Korean pine forest through a total of four treatments, control (CK), throughfall reduction (TR), N addition (N50) and throughfall reduction plus N addition (TR-N50). Plant root traits, glomalin-related soil proteins (GRSPs), soil properties and soil aggregates were investigated to explore how these treatments influenced soil structure. The results showed that six-year N addition and throughfall reduction had no significant effect on pH, carbon to nitrogen ratios (C/N ratios), microbial biomass carbon (MBC) and bulk density (BD), but an interactive effect of N addition and throughfall reduction on dissolved organic carbon (DOC) and soil organic carbon (SOC) was recorded. Root traits, such as root length density (RLD) and root weight density (RWD), decreased in the TR and TR-N50 plots compare with CK, especially RLD, which decreased by approximately 47.28% and 20.32%, respectively. GRSPs released from AMF associated with fine roots obviously decreased in the TR and TR-N50 treatments especially for total glomalin-related soil protein (TGRSP). Similar trends were observed for the proportion changes of >2 mm macroaggregates, whereas contrasting trends were observed for <2 mm aggregates in response to experimental treatments, resulting in decreased MWD in the TR-N50 treatment. These results indicated that the negative interactive effects of N addition and throughfall reduction on soil structure were mainly associated with biological binding agents (especially GRSPs), based on evidence from principal component analysis and Pearson correlations. Therefore, our results suggest that biological binding agents will strongly mediate soil aggregation under the perspective N deposition and precipitation change.

23503. 题目: Enhanced sludge dewatering via homogeneous and heterogeneous Fenton reactions initiated by Fe-rich biochar derived from sludge
文章编号: N19051108
期刊: Chemical Engineering Journal
作者: Shuangyi Tao, Jiakuan Yang, Huijie Hou, Sha Liang, Keke Xiao, Jingjing Qiu, Jingping Hu, Bingchuan Liu, Wenbo Yu, Huali Deng
更新时间: 2019-05-11
摘要: Fenton and Fenton-like sludge conditioning processes have been studied intensively due to their superior efficiency in improving sludge dewaterability. But these processes inevitably produce a large quantity of Fe-rich sludge cake that induces challenges for disposal. Herein a sustainable sludge recycling strategy has been developed by using sludge-derived Fe-rich biochar as an iron source and catalyst to enhance sludge dewatering via advanced oxidation processes. Both homogeneous Fenton reactions initiated by the leached Fe²⁺ from the biochar, and heterogeneous Fenton reactions initiated by the bonded iron, in forms of Fe₃O₄, on the surface of the biochar, are revealed to contribute to the increase the amount of OH generation during sludge conditioning, which further improved the release of bound water and sludge dewaterability. The stability of the dewatering performance using the new strategy is demonstrated via three consecutive reuse cycles, in which a stable water contents of dewatered sludge cakes of approximately 46.38 wt% ± 2.88 is obtained. The iron content of the biochar becomes stable after the 2nd round recycle. A reduction of 28.39% on the total operating cost of sludge treatment could be realized when compared with the Fenton conditioning system without sludge recycling. The proposed sustainable sludge recycling strategy could realize zero disposal Fe-containing sludge, and meanwhile produce biochar that can be beneficially reused as valuable functional materials for other applications.
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23504. 题目: Synergistic effects of low-/medium-vacuum carbonization on physico-chemical properties and stability characteristics of biochars
文章编号: N19051107
期刊: Chemical Engineering Journal
作者: Habib Ullah, Qumber Abbas, Muhammad Ubaid Ali, Amina, Ayesha Imtiyaz Cheema, Balal Yousaf, Jörg Rinklebe
更新时间: 2019-05-11
摘要: Vacuum carbonization is considered to be an effective and promising thermochemical-tool for resource and energy recovery by collecting and reusing pyrolysis products and volatiles. In this study, thermochemical conversion of orange peel to biochar under low- and medium-vacuum pyrolysis conditions were investigated for product distribution and stability characteristics of biochar. The pyrolysis experiments were executed under three different conditions i.e., N₂ atmosphere (without vacuum), low-vacuum (1013.2 Pa) and medium-vacuum (101.3 Pa) in the temperature range of 300–700 °C. The derived biochars were characterized for its aromaticity, polarity, elemental composition, pH, electrical conductivity, surface area, thermal decomposition, FTIR spectroscopy and chemical oxidation properties. Results revealed that low and medium-vacuum pyrolysis had an overriding effect on the H/C (aromaticity) and O/C (polarity) ratios, surface functional groups, as well as on the chemical oxidation potential of derived biochars. A significant reduction in biochar yield (1.1–1.9 folds), increased aromaticity with low H/C (1.3–2.0 folds) and O/C (1.95–4.75 folds) values was observed with increased pyrolysis temperature, under low- and medium-vacuum pyrolysis compared to the N₂ atmosphere. It was also found that biochar produced in the temperature range of 300–700 °C, under low and medium-vacuum pyrolysis were comparatively preferable to biochar stability. It is concluded that biochar produced at low-medium vacuum pyrolysis conditions shows higher carbon sequestration potential compared to the N₂ atmosphere.

23505. 题目: ‘Trapping and binding’: A review of the factors controlling the development of fossil agglutinated microbialites and their distribution in space and time
文章编号: N19051106
期刊: Earth-Science Reviews
作者: P. Suarez-Gonzalez, M.I. Benito, I.E. Quijada, R. Mas, S. Campos-Soto
更新时间: 2019-05-11
摘要: Trapping and binding of allochthonous grains by benthic microbial communities has been considered a fundamental process of microbialite accretion since its discovery in popular shallow-marine modern examples (Bahamas and Shark Bay). However, agglutinated textures are rare in fossil microbialites and, thus, the role of trapping and binding has been debated in the last four decades. Recently, renewed attention on this subject has produced new findings of fossil agglutinated microbialites (those mainly formed by ‘trapping and binding’ and analogous to modern examples), but they are still few and geologically recent (post-Paleozoic) when compared to the 3.5 Gyr long record of microbialites. In order to better understand this discrepancy between modern and fossil examples, an extensive literature review is presented here, providing the first thorough database of agglutinated microbialites, which shows that all of them are formed in shallow-marine environments and most under tidal influence. In addition, a Lower Cretaceous example is described, including very diverse microbialites, each of them formed in a particular paleoenvironment. Some of these microbialites developed in grainy settings, but only those formed in marginal-marine tide-influenced environments accreted mainly by trapping and binding the surrounding grains, being analogous of modern agglutinated microbialites, and matching the environmental pattern observed in the literature database. The combination of the literature review with the case study allows to discuss the factors that control and enhance ‘trapping and binding’: a) occurrence of grains in the microbialite environment; b) frequent currents that mobilize the grains and supply them onto the microbialite surface; c) high concentration and diversity of electrolytes in the water to increase the adhesiveness of the extracellular polymeric substances (EPS) of the microbialite surface; and d) a CaCO₃ saturation state not high enough to promote early and strong carbonate precipitation within EPS, which would eventually decrease its availability to adhere grains. Therefore, this review shows that the keys to solve the ‘trapping and binding’ debate may be environmental, because the conjuction of these hydrodynamic and hydrochemical parameters is preferentially achieved in shallow-marine settings and especially in those influenced by tides, at least since Mesozoic times. This explains the limited environmental and stratigraphic distribution of microbialites mainly formed by ‘trapping and binding’, and opens new ways to look, geologically and microbiologically, at this process, so often cited and yet so rare.

23506. 题目: Is the ‘enzyme latch’ or ‘iron gate’ the key to protecting soil organic carbon in peatlands?
文章编号: N19051105
期刊: Geoderma
作者: Yuan Wen, Huadong Zang, Qingxu Ma, Chris D. Evans, David R. Chadwick, Davey L. Jones
更新时间: 2019-05-11
摘要: Peatlands represent the largest natural terrestrial carbon (C) store, however, this C can become destabilized, particularly in response to anthropogenic disturbance or lowering of the water table. Several different paradigms have been proposed to explain the positive or negative relationships of moisture status with C loss rates in peat soils (e.g. ‘enzyme latch’, ‘iron gate’). The relative importance of these regulatory mechanisms and whether they are mutually exclusive, however, remain unknown. To address this, we evaluated the effects of contrasting soil moisture regime and iron concentration on organic matter mineralization in an agriculturally managed lowland fen peat. Our results showed that for the first 50 days of incubation, phenol oxidative activity under saturated conditions (120% water holding capacity; WHC) was lower than that at 65% WHC, but after this period the pattern was reversed. These results suggest that two different mechanisms may control phenol oxidative activity simultaneously, with the dominant controlling factor and final response being dependent on the trade-offs between oxygen and Fe(II) effects. Although Fe(II) addition increased phenol oxidative activity, it suppressed SOC mineralization regardless of the soil moisture content, suggesting that iron can protect soil C from microbial decomposition in lowland peat soils. Our study has implications for understanding the widely divergent biogeochemical functions of soil moisture on peat soils and emphasizes the influence of oxygen and Fe(II) on phenol oxidative activity and SOC mineralization.
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23507. 题目: Composition and turnover time of organic matter in soil fractions with different magnetic susceptibility
文章编号: N19051104
期刊: Geoderma
作者: Tommaso Chiti, Giacomo Certini, Fabio Marzaioli, Luigi Paolo D'Acqui, Claudia Forte, Simona Castaldi, Riccardo Valentini
更新时间: 2019-05-11
摘要: The composition and turnover time (TT) of organic matter in soil fractions with different magnetic susceptibility were studied in a tropical primary forest in Ghana. The starting hypothesis was that soil organic matter (SOM) composition and properties depend on the magnetic susceptibility of the minerals SOM is associated with. Soil samples from 0 to 5, 5–15, 15–30, and 30–50 cm depth intervals were sieved to remove rock fragments (>2.0 mm) and then separated into two size fractions (0.5–2.0 mm and <0.5 mm) that were processed by a High Gradient Magnetic Separator (HGMS) to finally obtain four fractions with different size and/or magnetic susceptibility. All fractions were analysed for their mineral composition, ¹⁴C concentration, and spectroscopic properties of SOM (¹³C CPMAS NMR).From a mineralogical point of view, the magnetic (MA) fractions essentially differed from the non-magnetic (NM) ones for a higher presence of oxides and kaolinite, which per se is non-magnetic. In terms of chemical composition of SOM, the MA fractions showed higher contribution of labile compounds than the NM ones. At all depths, the ¹⁴C concentration revealed shortest TT of SOM in the <0.5 mm MA fraction and longest TT in the <0.5 mm NM fraction, while the 0.5–2.0 mm fractions showed intermediate and similar TT's. At depths <5 cm, the fine NM fraction was not significantly influenced by the carbon fixed after the 1950s (“bomb carbon”), having TT of almost 1000 years and suggesting that in this tropical soil some SOM can be stabilized also in relatively superficial horizons.Our findings support the hypothesis that minerals are driving factors of the fate of SOM. As a consequence, soil fractionation based on magnetic susceptibility might be a meaningful procedure for having insight into SOM dynamics.

23508. 题目: Performance and microbial community structure of an aerobic granular sludge system at different phenolic acid concentrations
文章编号: N19051103
期刊: Journal of Hazardous Materials
作者: Barbara Muñoz-Palazon, Alejandro Rodriguez-Sanchez, Miguel Hurtado-Martinez, Ines Manuel de Castro, Belén Juarez-Jimenez, Alejandro Gonzalez-Martinez, Jesus Gonzalez-Lopez
更新时间: 2019-05-11
摘要: The present work aims to use aerobic granular sludge technology for the treatment of wastewater containing high organic matter loads and a mixture of phenolic compounds normally present in olive washing water. The physicochemical performance of five bioreactors treating different concentrations of mixture of phenolic acid was monitored to observe the response of the systems. The bioreactors that operated at 50, 100 and 300 mg L⁻¹ did not show relevant changes in terms of performance and granules properties, showing high ratio of phenolic compound removal ratio. However, the bioreactors operated with high phenolic compound concentrations showed low rates of organic matter, nitrogen and phenolic acid removal. In the same way, high concentrations of phenolic compounds determined the disintegration of the granular biomass. Next-generation sequencing studies showed a stable community structure in the bioreactors operating with 50, 100 and 300 mg L⁻¹ of phenolic acids, with the genera Lampropedia and Arenimonas, family Xanthobacteraceae and Fungi Pezizomycotina as the dominant phylotypes. Conversely, the reactors operated at 500 and 600 mg L⁻¹ of phenolic substances promoted the proliferation of Oligohymenophorea ciliates. Thus, this study suggests that aerobic granular sludge technology could be useful for the treatment of wastewaters such as olive washing water.

23509. 题目: Using sequential extraction and DGT techniques to assess the efficacy of plant- and manure-derived hydrochar and pyrochar for alleviating the bioavailability of Cd in soils
文章编号: N19051102
期刊: Science of The Total Environment
作者: Lanfang Han, Xingjuan Zhao, Jie Jin, Bo Gao, Yan Yang, Ke Sun, Fangbai Li
更新时间: 2019-05-11
摘要: Biochar has emerged as a useful tool to reduce the bioavailability of heavy metals in contaminated soils. However, limited research has been directed towards determining the effects of pyrolysis conditions and feedstock types of biochar on the bioavailability of heavy metals in biochar-treated soils. This work evaluated the efficacy of plant- and manure-derived hydrochar and pyrochar for alleviating Cd bioavailability in soils using conventional chemical extraction, diffusive gradients in thin films (DGT) and plant uptake. For each feedstock type, hydrochar showed lower maximum adsorption capacity than pyrochar. As determined by diethylenetriamine pentaacetic acid, BCR extraction and DGT measurement, pyrochar significantly decreased the theoretical bioavailability of Cd. Moreover, a slight decrease in the ability of soil to resupply Cd to the solution was detected. Also, pyrochar induced a substantial reduction in Cd uptake in ryegrass. Corresponding to the high sorption capacity, swine solid-derived 450 °C pyrochar was the most effective in alleviating Cd bioavailability in soils, indicating its great potential for remediating Cd-contaminated soils. Additionally, the bioavailable Cd amount determined by DGT had the best correlation with the Cd content in ryegrass, showing that DGT technology could better represent the effects of biochars on Cd phytoavailability in the studied soil.
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23510. 题目: Assessing the provision of carbon-related ecosystem services across a range of temperate grassland systems in western Canada
文章编号: N19051101
期刊: Science of The Total Environment
作者: Majid Iravani, Shannon R. White, Daniel R. Farr, Thomas J. Habib, Jahan Kariyeva, Monireh Faramarzi
更新时间: 2019-05-11
摘要: Reliable data on the provision of ecosystem services (ES) is essential to the design and implementation of policies that incorporate ES into grassland conservation and restoration. We developed and applied an innovative approach for regional parameterization, and calibration of the CENTURY ecosystem model. We quantified spatiotemporal variation of soil organic carbon stock (SOC) and aboveground plant biomass production (AGB) and examined their responses to the recent climate change across a diverse range of native grassland systems in Alberta, western Canada. The simultaneous integration of SOC and AGB into calibration and analysis accounted for most of the spatiotemporal variability in the SOC and AGB measurements and resulted in reduced simulation uncertainty across nine grassland regions. These findings suggest the importance of the systematic parameterization and calibration for the reliable assessment of carbon-related ES across a wide geographic area with heterogeneous ecological conditions. Simulation results showed a pronounced variation in the spatial distribution of SOC and AGB and their associated uncertainty across grassland regions. Under baseline grazing intensity regime, an overall negative effect of recent climatic changes on the SOC, and a less consistent effect on the AGB were found. While, an overall positive or slightly negative impact of recent climate change on the SOC and AGB was found under a proposed 10% lower grazing intensity regime. These heterogeneities in the magnitude and direction of climate change effects under different grazing regimes suggest needs for a range of climate change adaptation strategies to maintain carbon-related ES in Alberta's grasslands. The modeling framework developed in this study can be used to improve the spatially explicit assessment of carbon-related ES in other geographically vast grassland areas and examine the effectiveness of alternative management scenarios to ensure the long-term provision of carbon-related ES in grassland systems.
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23511. 题目: Linking the reclaimed soils and rehabilitated vegetation in an opencast coal mining area: a complex network approach
文章编号: N19051009
期刊: Environmental Science and Pollution Research
作者: Zhaotong Zhang, Jinman Wang, Yu Feng
更新时间: 2019-05-10
摘要: As two main factors, soil and vegetation play key roles in land rehabilitation and ecological remediation of mining areas. There is a complex interaction between soil and vegetation, and understanding the mechanisms of interaction between soil and vegetation is of great significance for land rehabilitation and ecological remediation in mining areas. This study introduced complex network method to analyze the complex interaction systematically. A survey of vegetation and soil properties in 70 reclaimed plots was carried out in the Anjialing and Antaibao opencast coal-mines in Shanxi, China. The indices of soil and vegetation acted as nodes, and the interaction between these indices as sides to establish a soil-vegetation network. Calculating the network indices to analyze the structure of a complex network and explore the mechanism of interaction between soil and vegetation. SOM (soil organic matter) was at the core of the soil-vegetation interaction network. The average path length of the soil-vegetation network was 1.8, with a faster rate of information transfer. The soil-vegetation network consisted of three clusters (soil physical property cluster, soil chemical property cluster, and vegetation cluster), in which the soil chemical property cluster owned the highest clustering coefficient and the largest number of triangles, and it was most stable and the interaction within the cluster was strongest. The soil-vegetation network was stable and the connectivity of the network had robustness to node failures. The scale of the network became larger and the network became tighter and more stable with the increase of reclamation time. Some measures should be conducted to promote vegetation restoration by improving important soil nodes, e.g., surface soil covering, applying organic fertilizer, and planting nitrogen-fixing plants.

23512. 题目: Effects of Ozone on the Photochemical and Photophysical Properties of Dissolved Organic Matter
文章编号: N19051008
期刊: Environmental Science & Technology
作者: Frank Leresche, Garrett McKay, Tyler Kurtz, Urs von Gunten, Silvio Canonica, Fernando L. Rosario-Ortiz
更新时间: 2019-05-10
摘要: This study focused on the effects of ozonation on the photochemical and photophysical properties of dissolved organic matter (DOM). Upon ozonation, a decrease in DOM absorbance was observed in parallel with an increase in singlet oxygen (¹O₂) and fluorescence quantum yields (Φ_1O2 and Φ_F). The increase in Φ_1O2 was attributed to the formation of quinone-like moieties during ozonation of the phenolic moieties of DOM, while the increase in Φ_F can be explained by a significant decrease in the internal conversion rate of the first excited singlet state of the DOM (¹DOM*). It is a consequence of an increase in the average energy of the first electronic transition (S₁ → S₀) that was assessed using the wavelength of maximum fluorescence emission (λ_F,max). Furthermore, ozonation did not affect the ratio of the apparent steady-state concentrations of excited triplet DOM (³DOM*) and ¹O₂, indicating that ozonation does not affect the efficiency of ¹O₂ production from ³DOM*. The consequences of these changes for the phototransformation rates of micropollutants in surface waters were examined using photochemical model calculations. The decrease in DOM absorbance caused by ozonation leads to an enhancement of direct photolysis rates due to the increased transparency of the water. Rates of indirect photooxidation induced by ¹O₂ and ³DOM* slightly decrease after ozonation.
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23513. 题目: Global Meta‐analysis on the Relationship between Mercury and Dissolved Organic Carbon in Freshwater Environments
文章编号: N19051007
期刊: Journal of Geophysical Research: Biogeosciences
作者: Raphael A. Lavoie, Marc Amyot, Jean‐François Lapierre
更新时间: 2019-05-10
摘要: In freshwater ecosystems, several studies have shown a strong linear relationship between total mercury (THg) or methylmercury (MeHg) and dissolved organic carbon (DOC) concentrations. Variations in this linear relationship have been reported, but the magnitude and causes of this variation are not well known. The objective of this study was to conduct a meta‐analysis to quantify and understand the global variation of this mercury (Hg)–DOC association. This meta‐analysis included 54 studies in lentic and lotic ecosystems for a total of 85 THg–DOC and 59 MeHg–DOC relationships. There was an increase in Hg with DOC concentrations in water with a global average slope of 0.25 (confidence interval (CI): 0.20–0.35) ng/mg for THg and 0.029 (CI: 0.014–0.044) ng/mg for MeHg. Relationships were stronger for (1) North American studies; (2) natural environments compared to those disturbed by anthropogenic activities; (3) spatial studies compared to temporal studies; (4) filtered samples (THg only); and (5) the aromatic fraction of DOC compared to the bulk DOC. Coupling with DOC was stronger for THg than for MeHg. Ecosystem type (lentic vs. lotic), geographical coordinates, and publication year did not influence the strength of relationships. Overall we show that there is a strong but variable coupling between carbon and mercury cycles in freshwater ecosystems globally and that this link is modulated regionally by geographic location, temporal scale, and human activity, with implications for understanding these rapidly changing biogeochemical processes in response to global change.

23514. 题目: Initial lignin content is an indicator of predicting leaf litter decomposition and the mixed effects of two perennial gramineous plants in a desert steppe, a five‐year long‐term study
文章编号: N19051006
期刊: Land Degradation & Development
作者: Hao Qu, Chengchen Pan, Xueyong Zhao, Jie Lian, Shaokun Wang, Xinyuan Wang, Xujun Ma, Liangxu Liu
更新时间: 2019-05-10
摘要: Leaf is the main component of litter which often exists in mixed forms in nature. However, the mixed effects of leaf litter decomposition in the desert ecosystems remain unclear. To reveal the mixed effects and the influence of litter quality on leaf litter decomposition in desert ecosystems, a five year long‐term study was conducted to compare the observed and expected leaf litter mass loss in single‐species and mixed (equal proportions and natural proportions) litters of two typical perennial gramineous plants (Stipa klemenzii and Achnatherum splendens) in a desert steppe in northern China. The relationship between litter mass loss and litter qualities was also analyzed. The results showed that: (1) after 5 years of decomposition, the mass losses of mixed litter in natural proportions and Stipa klemenzii litter were significantly higher than those of mixed litter in equal proportions and Achnatherum splendens litter; (2) the mixed effects of two litters in different ratios varied with time, and the synergistic effect only appeared in the second year when an easily decomposed litter (Stipa klemenzii) was mixed with a slowly decomposing litter (Achnatherum splendens); (3) litter mass loss was not correlated with the initial carbon or nitrogen content but was negatively correlated with the initial lignin content, and the initial lignin content also had a significant effect on litter mixed effects of these two perennial gramineous plant litters. These results can suggest that the initial lignin content is an indicator of predicting decomposition and mixed effects of litter with low nitrogen content.

23515. 题目: Influence of reclaimed water irrigation in soil physical properties of urban parks: A case study in Madrid (Spain)
文章编号: N19051005
期刊: CATENA
作者: David Zalacáin, Ramón Bienes, Antonio Sastre-Merlín, Silvia Martínez-Pérez, Andrés García-Díaz
更新时间: 2019-05-10
摘要: Reclaimed water irrigation has been a long-standing practice, especially among water deficit areas such as Spain. This kind of water, more mineralized than drinking water, could imply changes on structural soil features. The main aim of this study was to assess the impact of reclaimed water on aggregate stability, soil penetration resistance, infiltration rate and porosity in soils of one of the urban parks of Madrid. This research was carried out on five successive years (2012–2016) in two urban park plots: one irrigated with reclaimed water (RW) and another one with drinking water (DW).Results showed that irrigation with reclaimed water increased microaggregate stability in the topsoil, probably because of higher values of soil organic matter (SOM). However, macroaggregate stability decreased after RW irrigation in the top and the deepest layer. Soil penetration resistance was significantly higher in the RW plot, probably due to a further development of the root system. Furthermore, a decrease on infiltration rate was observed for RW, apparently because of the influence of sodium. On the other hand, porosity results showed that there was no influence of the kind of irrigation water used. The prolonged use of reclaimed water to irrigate urban parks is potentially leading to a modification of some soil properties, which are key in urban parks soil system. Thus, to avoid future problems, the use of reclaimed water in urban parks irrigation should be continuously monitored.

23516. 题目: Changes in soil carbon pools and components induced by replacing secondary evergreen broadleaf forest with Moso bamboo plantations in subtropical China
文章编号: N19051004
期刊: CATENA
作者: Chuanbao Yang, Huijing Ni, Zheke Zhong, Xiaoping Zhang, Fangyuan Bian
更新时间: 2019-05-10
摘要: Moso bamboo (Phyllostachys edulis) is widely distributed in southern China, and is one of the fastest growing plants worldwide; however, information remains limited on the impact of converting secondary broad-leaved evergreen forests to Moso bamboo plantations, and how the soil organic carbon (SOC) pool and its chemical composition should be managed subsequently. To elucidate these effects, three representative areas were chosen, all with very similar site conditions. In each area, four comparable stands were selected; namely, undisturbed (M0), extensively managed (M1), and intensively managed (M2) stands in each Moso bamboo plantation, and a secondary broad-leaved evergreen forest (CK). Soil samples were collected and examined from depths of 0–20 and 20–40 cm in all 12 stands. The results showed that, SOC and mineral-associated organic matter C (MOM-C) stocks in 0–40 cm soil depths were significantly higher in M0 and M1 than in CK; however, these two parameters were significantly lower in M2. M0 and M1 showed a significant decline in the ratio of microbial biomass C (MBC) to total organic C (TOC), hot-water-extractable organic C (DOC) to TOC, and the C mineralization rate. However, M2 showed a significant increase compared to CK for all of these parameters. Fourier-transform infrared spectroscopy (FTIR) showed that land-use conversion also changed SOC chemical composition. Compared with CK and M2, M0 and M1 showed lower relative content of polysaccharides and higher content of recalcitrant compounds and soil hydrophobicity. Aliphatic and aromatic compounds were positively correlated with accumulated C sequestration in all fractions but negatively correlated with microbial activity in both soil layers; thus, chemical protection mechanism was important for stabilizing the soil in M0 and M1. Overall, Moso bamboo plantations with management strategies M0 and M1 could stabilize more C through promoting the formation of stable organic-mineral complexes and the accumulation of resistant organic components, showing much higher potential in terms of soil C sequestration than M2.

23517. 题目: Anode potentials regulate Geobacter biofilms: New insights from the composition and spatial structure of extracellular polymeric substances
文章编号: N19051003
期刊: Water Research
作者: Guiqin Yang, Lingyan Huang, Zhen Yu, Xiaoming Liu, Shanshan Chen, Jianxiong Zeng, Shungui Zhou, Li Zhuang
更新时间: 2019-05-10
摘要: The extracellular electron transfer (EET) efficiency in bioelectrochemical systems has been proven to be dependent on anode potentials. To explore the underlying mechanism, previous studies have mainly focused on EET conduit and bacterial biomass but rarely concerned with the role of extracellular polymeric substances (EPS) surrounding electroactive cells. In this study, the response of Geobacter biofilms to anode potentials was investigated with a special emphasis on the mechanistic role of EPS. The electrochemical activities and cell viabilities of Geobacter soli biofilms were simultaneously attenuated at 0.4 and 0.6 V compared to −0.2 and 0 V. It was found that the biofilms (especially the biofilm region closer to electrode surface) grown at −0.2 and 0 V produced relatively more extracellular redox-active proteins and less extracellular polysaccharides, which conferred higher electron accepting/donating capacities to EPS and consequently facilitated EET. Meanwhile, electrically nonconductive extracellular polysaccharide-dominated interior layers were formed in the biofilms grown at 0.4 and 0.6 V, which limited direct EET but might serve as physical barriers for protecting cells in these biofilms from the increasing stress by poised electrodes. These results demonstrated that the production of EPS under different anode potentials might be finely regulated by cells to keep balance between EET efficiency and cell-protection. This study provides a new insight to investigate the Geobacter biofilms coping with various environments, and is useful for optimizing electrochemical activity of anode biofilms.
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23518. 题目: Organic matter removal and membrane fouling mitigation during algae-rich surface water treatment by powdered activated carbon adsorption pretreatment: Enhanced by UV and UV/chlorine oxidation
文章编号: N19051002
期刊: Water Research
作者: Jiajian Xing, Heng Liang, Siqi Xu, Chuah Chong Joon, Xinsheng Luo, Tianyu Wang, Jinlong Wang, Guibai Li, Shane A. Snyder
更新时间: 2019-05-10
摘要: In this work, UV and UV/chlorine (UV/Cl) were employed to enhance powdered activated carbon (PAC) adsorption pretreatment prior to ultrafiltration process for algae-contaminated surface water treatment. Their performance on membrane fouling mitigation and organic pollutant rejection was systematically evaluated. A comparative experiment was conducted under varying pollution degrees of algal extracellular organic matter (EOM) contamination in surface river water. The results indicated that UV/PAC and UV/Cl/PAC pretreatment effectively enhanced the removal of dissolved organic carbon (DOC) and UV-absorbing at 254 nm (UV₂₅₄). The characteristics of feed water after pretreatments were investigated through apparent molecular-weight (MW) distribution and fluorescence parallel factor analysis (PARAFAC). In regard to membrane fouling mitigation, UV/Cl/PAC noticeably decreased reversible and irreversible fouling resistance simultaneously and UV/PAC preferred reducing reversible membrane fouling. Combined fouling modeling was operated to scrutinize the fouling mitigation mechanisms and standard pore blocking was proved to be dominant during the filtration process. Moreover, the UV/Cl and UV/Cl/PAC pretreatments were proved positive for emerging micropollutants degradation and disinfection by-products formation potential reduction. The results suggested that UV and UV/Cl are likely strategies to enhance the efficiency of PAC adsorption pretreatments prior to ultrafiltration during algae-contaminated water treatment.
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23519. 题目: Chlorite formation during ClO₂ oxidation of model compounds having various functional groups and humic substances
文章编号: N19051001
期刊: Water Research
作者: Wenhui Gan, Sirong Huang, Yuexian Ge, Tom Bond, Paul Westerhoff, Jiaxin Zhai, Xin Yang
更新时间: 2019-05-10
摘要: Chlorine dioxide (ClO₂) has been used as an alternative to chlorine in water purification to reduce the formation of halogenated byproducts and give superior inactivation of microorganisms. But the formation of chlorite (ClO₂⁻) is a major consideration in the application of ClO₂. In order to improve understanding in ClO₂⁻ formation kinetics and mechanisms, this study investigated the reactions of ClO₂ with 30 model compounds, 10 humic substances and 2 surface waters. ClO₂⁻ yields were found to be dependent on the distribution of functional groups. ClO₂ oxidation of amines, di- and tri-hydroxybenzenes at pH 7.0 had ClO₂⁻ yields >50%, while oxidation of olefins, thiols and benzoquinones had ClO₂⁻ yields <50%. ClO₂⁻ yields from humic substances depended on the ClO₂ dose, pH and varied with different reaction intervals, which mirrored the behavior of the model compounds. Phenolic moieties served as dominant fast-reacting precursors (during the first 5min of disinfection). Aromatic precursors (e.g., non-phenolic lignin or benzoquinones) contributed to ClO₂⁻ formation over longer reaction times (up to 24 h). The total antioxidant capacity (indication of the amount of electron-donating moieties) determined by the Folin-Ciocalteu method was a good indicator of ClO₂-reactive precursors in the water, which correlated with the ClO₂ demand of waters. Waters bearing high total antioxidant capacity tended to generate more ClO₂⁻ at equivalent ClO₂ exposure, but the prediction in natural water should be conservative.

23520. 题目: Influence of individual and combined application of biochar, Bacillus megaterium , and phosphatase on phosphorus availability in calcareous soil
文章编号: N19050920
期刊: Journal of Soils and Sediments
作者: Xiangru Zhang, Haixiao Li, Meng Li, Guoqi Wen, Zhengyi Hu
更新时间: 2019-05-09
摘要: Purpose: Phosphorus (P) in calcareous soil often needs to be replenished repeatedly. P-enriched biochar is expected to improve soil available P. However, the effect of acid biochar incorporated with other P activators on the P availability in calcareous soil is rarely reported. Materials and methods: One soil incubation for 56 days was conducted to investigate the influence of individual application of acid biochar (B), phosphatase (E), Bacillus megaterium (M), and their combined application (BE, BM, EM, BEM) on soil P availability, based on analysis of Olsen-P, water-soluble P, P forms, acid phosphomonoesterase (AcP), alkaline phosphomonoesterase (AlP) activity, and pH after 7, 14, 28, and 56 days of incubation. Results and discussion: Results indicated that individual application of B significantly increased soil Olsen-P and AcP compared with CK in the whole incubation period. Individual application of M significantly increased soil AcP and AlP on the 14th and 56th day of incubation, but decreased soil Olsen-P significantly in the whole incubation. Conclusions: Individual application of B was the best measure for improving P availability in calcareous soil, followed by application of BM. But individual application of E or M was not recommended. Further investigations are required to investigate the influence of acid biochar on P availability in calcareous soil at the field scale.