论文检索

总访问量：4705410次

总访客量：218218人

所有论文

28081. 题目: Effects of topographic factors and aboveground vegetation carbon stocks on soil organic carbon in Moso bamboo forests
文章编号: N18112304
期刊: Plant and Soil
作者: Huiyun Fang, Biyong Ji, Xu Deng, Jiayang Ying, Guomo Zhou, Yongjun Shi, Lin Xu, Jixing Tao, Yufeng Zhou, Chong Li, Hao Zheng
更新时间: 2018-11-23
摘要: Background and aims: Forest soil organic carbon (SOC) plays an important role in the carbon cycle of forest ecosystems and in mitigating climate change effects. This study aimed to investigate the effects of topographic factors (aspect, altitude, slope position, and slope gradient) and aboveground vegetation carbon stocks on SOC stocks in Moso bamboo forests in Zhejiang Province, China. Methods: We used generalized linear models and one-way analysis of variance (ANOVA) to analyze the effects of topographic factors and aboveground vegetation carbon stocks on SOC stocks. Results: SOC stocks on the north (N) aspects were greater than those on the south (S) aspects, independent of soil layers; SOC stocks positively correlated with altitude and slope gradient in surface soils (0–30 cm), but negatively correlated with slope position in the deep soil layer (60–100 cm). Aboveground vegetation carbon stocks significantly affected the SOC stocks on the S aspect, the moderate slope, and lower and middle slopes. The stratification ratio of SOC stocks was influenced by topographic factors, particularly slope position and gradient. Conclusion: Our findings contribute to the body of knowledge regarding how topographic factors and aboveground vegetation carbon stocks affect SOC stocks in different soil layers and provide basic data for model simulation of SOC stocks.

28082. 题目: Comparison of different methods for determining lignin concentration and quality in herbaceous and woody plant residues
文章编号: N18112303
期刊: Plant and Soil
作者: Sibylle Faust, Klaus Kaiser, Katja Wiedner, Bruno Glaser, Rainer Georg Joergensen
更新时间: 2018-11-23
摘要: Aims: Acid detergent lignin (ADL), acetyl bromide (AcBr), and cupric oxide oxidation (CuO) were compared as methods for determining lignin concentration and quality in plant residues. Methods: These three methods were used to analyze 27 plant residues from different groups of species, i.e., legumes, crucifers, herbs, grasses, and trees. Results: Median lignin concentrations of the 27 plant materials were 4.5% ADL and 6.0% AcBr lignin, significantly exceeding the median of 2.1% CuO lignin. ADL concentrations varied from 0.8 to 27.0%; those of AcBr and CuO lignin ranged from 1.8 to 12.2% and from 0.6 to 9.7%, respectively. AcBr lignin showed a significant negative, non-linear relationship with total N. In addition, the relationship of ADL and CuO data was negatively affected by total N. Conclusion: The ADL method is simple and well reproducible, and large datasets are available for comparison. The AcBr procedure is fast, with less interference from non-lignin products than ADL. The CuO method is not interfered with by any other organic component in the plant material and gives additional information on the composition of the lignin. However, the release of phenolic units may be incomplete.

28083. 题目: Carbon mineralization and microbial activity in agricultural topsoil and subsoil as regulated by root nitrogen and recalcitrant carbon concentrations
文章编号: N18112302
期刊: Plant and Soil
作者: Zhi Liang, Lars Elsgaard, Mette Haubjerg Nicolaisen, Annemette Lyhne-Kjærbye, Jørgen Eivind Olesen
更新时间: 2018-11-23
摘要: Aims: Mechanisms of subsoil carbon sequestration from deep-rooted plants are elusive, but may contribute to climate change mitigation. This study addressed the role of root chemistry on carbon mineralization and microbiology in a temperate agricultural subsoil (60 and 300 cm depth) compared to topsoil (20 cm depth). Methods: Roots from different plant species were chemically characterized and root-induced CO₂ production was measured in controlled soil incubations (20 weeks). Total carbon losses, β-glucosidase activity, carbon substrate utilization, and bacterial gene copy numbers were determined. After 20 weeks, resultant carbon mineralization responses to mineral nitrogen (N) were tested. Results: Root-induced carbon losses were significantly lower in subsoils (32–41%) than in topsoil (58%). Carbon losses varied according to root chemistry and were mainly linked to root N concentration for subsoils and to lignin and hemicellulose concentration for topsoil. Increases in β-glucosidase activity and bacterial numbers in subsoils were also linked to root N concentration. Added mineral N preferentially stimulated CO₂ production from roots with low concentrations of N, lignin and hemicellulose. Conclusions: The results were compatible with a concept of N availability and chemically recalcitrant root compounds interacting to control subsoil carbon decomposition. Implications for carbon sequestration from deep-rooted plants are discussed.

28084. 题目: Adsorptive removal of As(V) by crawfish shell biochar: batch and column tests
文章编号: N18112301
期刊: Environmental Science and Pollution Research
作者: Jinpeng Yan, Yingwen Xue, Li Long, Yifan Zeng, Xiaolan Hu
更新时间: 2018-11-23
摘要: As a toxic and metalloid substance, excess arsenic (As) can cause serious harm to the environment and public health. In this work, crayfish shell biochar (CFS450) and modified biochar (MCFS450) were prepared to remove As(V) from aqueous solutions under various conditions. Compared to CFS450, MCFS450 had a higher specific surface area, better pore structure, and higher As(V) adsorption capacity. Based on the Langmuir model, its maximum As(V) adsorption capacity was 17.2 mg/g. The biochar had a large number of surface functional groups such as C-O, O-H, and -OH. After modification, a certain mass of ZnO nanoparticles existed on MCFS450, which increased positive charge on the surface and promoted the adsorption of As(V). As the temperature rose, the adsorption capacity increased, suggesting the adsorption was endothermic. Under low PH conditions, the adsorption effect was better. When Cl⁻, HCO₃⁻, SO₄²⁻, and PO₄³⁻ respectively existed, the adsorption capacity decreased, indicating that As(V) competed with other anions. The column adsorption experiments showed that Thomas, Yoon-Nelson, and Adams-Bohart models can be expressed as a unified model (EXY model). The EXY model can be used for the design of biochar-based filter for As(V) removal, providing a theoretical basis for practical production applications.

28085. 题目: Response of symbiotic and asymbiotic nitrogen-fixing microorganisms to nitrogen fertilizer application
文章编号: N18112205
期刊: Journal of Soils and Sediments
作者: Yaying Li, Fuxia Pan, Huaiying Yao
更新时间: 2018-11-22
摘要: Purpose: Biological nitrogen fixation (BNF) plays an important role in nitrogen cycling by transferring atmospheric dinitrogen to the soil. BNF is performed by symbiotic and asymbiotic nitrogen-fixing microorganisms. However, the abundance, activity, and community structure of diazotrophs under different nitrogen fertilizer application rates and how root exudates influence diazotrophs remain unclear. Materials and methods: ¹⁵N-N₂ and ¹³C-CO₂ labeling, DNA-based stable isotope probing (SIP), and molecular biological techniques were used in this study. The abundance, activity, and structure of symbiotic and asymbiotic diazotrophs under different nitrogen fertilizer applications in paddy soil were investigated. Results and discussion: We found that the nitrogen fixation capacity in milk vetch (Astragalus sinicus L.) and nifH gene abundance in the root nodules were significantly higher in the low-nitrogen treatment than in the control (zero) and high-nitrogen treatments. Nitrogen-fixing bacteria were abundant in the soils with a high biodiversity. Soil nifH gene sequences were dominated by α-, β-, and δ-proteobacteria, as well as by Cyanobacteria. The relative abundance of α-proteobacteria was lower, and the relative abundance of Cyanobacteria was higher under high nitrogen. Incubation of soil with ¹³CO₂ and subsequent DNA-SIP analysis demonstrated that OTU65 from α-proteobacteria was relatively more abundant in heavy fractions of the ¹³C-labeled soils than that in the unlabeled soils, indicating that α-proteobacteria may prefer rhizodeposition carbon to other organic carbon. However, OTU24 and OTU73 from δ-proteobacteria had relatively high abundances in light fractions both in the ¹³C-labeled and unlabeled samples, indicating that δ-proteobacteria may prefer other soil organic carbon to rhizodeposition carbon. Conclusions: The results suggested that soil N availability and rhizodeposition strongly modified the microbial communities of nitrogen-fixing bacteria. Moderate nitrogen application increased the symbiotic biological N fixing activity in the Astragalus sinicus L. rhizosphere. The BNF activity in the legume-rhizobia system is regulated by the exchange of organic C and N nutrient between the host plant and N-fixing bacteria.

28086. 题目: Pyrosequencing-based assessment of soil microbial community structure and analysis of soil properties with vegetable planted at different years under greenhouse conditions
文章编号: N18112204
期刊: Soil and Tillage Research
作者: Jian Zhang, Pengcheng Wang, Hongmei Tian, Qingqing Xiao, Haikun Jiang
更新时间: 2018-11-22
摘要: Soil microbes play an important role in maintaining soil health, and identifying microbial changes in greenhouse soils is vital for improving soil quality. This study was aimed to investigate the changes in microbial diversity and soil characteristics at different cultivation years in greenhouse vegetable production at different sites. Soil DNA was extracted, and bacterial v4-v5 16S rRNA and fungal internal transcribed spacer gene region were pyrosequenced to analyze the microbial communities. Soil properties and enzymatic activities were determined. Soil pH decreased and showed strong linkage to microbial community compositions, whereas soil organic matter increased. Significant increases were observed not only in the total but also in the available nitrogen (N) (AN), phosphorus (P) (AP), and potassium (K) (p < 0.05). Proteobacteria, Firmicutes, and Bacteroidetes were significantly enriched (p < 0.05) under different cultivation years, whereas Chloroflexi and Acidobacteria were significantly decreased. The predominant fungal phylum was Ascomycota whereas Basidiomycota and Actinomycetes exhibited significant decreases (p < 0.05). AP was strongly linked to bacterial structure, whereas AN was strongly related to fungal distribution. Our results suggest that soil bacteria and fungi respond differently to cultivation years under greenhouse conditions. This study provides insights into the improvement of soil quality in protected agricultural production.

28087. 题目: The elemental composition of the deep particle flux in the Sargasso Sea
文章编号: N18112203
期刊: Chemical Geology
作者: M.H. Conte, A.M. Carter, D. Koweek, S. Huang, J.C. Weber
更新时间: 2018-11-22
摘要: The elemental composition of the deep particle flux at 500 m, 1500 m and 3200 m was measured at the Oceanic Flux Program (OFP) time-series site in the northern Sargasso Sea from September 2000 to March 2015. The results clearly show that the deep particle flux is sourced from two components: an “extrinsic flux” component that is derived from and temporally coupled with recent surface export fluxes, and an “intrinsic flux” component that is derived from chemical scavenging and suspended particle aggregation within the deep water column. Elemental fluxes show a seasonal cycle that is closely tied to the overlying cycle in primary production. Fluxes of biogenic minerals and nutrient elements peak during the late winter-spring maximum in overlying primary production. A small late winter-spring peak in fluxes of non-biogenic elements suggests that intrinsic flux generation within the deep water column also covaries with overlying production and the extrinsic flux. Flux elemental composition also shows a marked seasonal cycle that reflects dilution of the intrinsic flux in the late winter and spring with fresh biogenic materials sourced from recent overlying production. Factor of four increases in lithogenic element fluxes and lithogenic element ratios indicate that the source of the deep lithogenic flux is not Saharan dust but North American margin sediments that have been resuspended and advected to the region via Gulf Stream recirculation. High rates of authigenic mineral precipitation accompany organic matter degradation in mesopelagic waters. The excess Mn flux (i.e. flux not supported by lithogenic minerals) increases by an order of magnitude between 500 m and 1500 m, and the excess Ba flux increases by a factor of three. There is a major reorganization of element associations with flux carrier phases with increasing depth. In particular, the geochemical behavior and flux of P becomes increasingly independent of organic carrier phases and the geochemical behavior of Fe, Co, Ni, Cu and, to a lesser extent, V and Pb becomes increasingly controlled by manganese oxide scavenging.This article is part of a special issue: “Cycles of trace elements and isotopes in the ocean – GEOTRACES and beyond” - Edited by “Tim M. Conway, Tristan Horner, Yves Plancherel, and Aridane G. González”.

28088. 题目: Nitrogen removal in the sediments of the Pearl River Estuary, China: Evidence from the distribution and forms of nitrogen in the sediment cores
文章编号: N18112202
期刊: Marine Pollution Bulletin
作者: Yiguo Hong, Jiapeng Wu, Fengjie Guan, Weizhong Yue, Aimin Long
更新时间: 2018-11-22
摘要: In this study, the spatial distribution and forms of nitrogen in sediment cores collected from the Pearl River Estuary were analyzed. Exchangeable nitrogen (N_ex) comprised only a small proportion of total nitrogen (N_tot), with a mean of 3.54% in the sediment cores. NH₄⁺ was the main form of N_ex. No obvious change was observed in the vertical content of fixed ammonia (N_fix) in the sediments, and the mean N_fix in all five sediment cores was 141.23 mg·kg⁻¹. The organic nitrogen (N_org), strongly related to organic carbon (C_org), was the main form in N_tot. The dissolved inorganic nitrogen in sediment pore water was much lower than that in estuarine water and no significant variation was observed from upstream to downstream. Our results indicated that most nitrogen deposited on surface sediments from overlying water was rapidly removed by a series of microbial processes, reducing the extent of nitrogen returning to overlying waters.

28089. 题目: Impact of eutrophication on arsenic cycling in freshwaters
文章编号: N18112201
期刊: Water Research
作者: Ying Tang, Meiyi Zhang, Guoxin Sun, Gang Pan
更新时间: 2018-11-22
摘要: Many arsenic-bearing freshwaters are facing with eutrophication and consequent algae-induced anoxia/hypoxia events. However, arsenic cycling in eutrophic waters and its impact on public health are poorly understood. Laboratory simulation experiments are performed in this study to study the effect of algal blooms on the cycling of arsenic in a sediment–water–air system. We found that the anoxia induced by the degradation of algal biomass promoted an acute arsenic (mostly As(III)) release within two days from sediment to both the water and atmosphere, and the release effluxes were proportional to the algae dosage. The reduction and methylation of arsenic were enhanced at the sediment–water interface, owing to the significant increase in arsenate reductase genes (arrA and arsC), and arsenite methyltransferase genes (arsM) caused by increased anoxia. The analysis of synchrotron-based X-ray absorption spectroscopy indicated that the concomitantly released natural organic matter (NOM) and sulfur (S) at the sediment–water interface reduced the As(III) release to a certain extent in the later reducing period of incubation, by forming As₂S₃ (43–51%) and As(III)-Fe-NOM (28–35%). Our results highlight the needs for the in-situ assessment of volatile arsenic in eutrophic freshwaters with its risk to human and animal health.
图文摘要:

28090. 题目: Toxic algal bloom induced by ocean acidification disrupts the pelagic food web
文章编号: N18112110
期刊: Nature Climate Change
作者: Ulf Riebesell, Nicole Aberle-Malzahn, Eric P Achterberg, María Algueró-Muñiz, Santiago Alvarez-Fernandez, Javier Arístegui, Lennart T Bach, Maarten Boersma, Tim Boxhammer, Wanchun Guan, Mathias Haunost, Henriette G Horn, Carolin R Löscher, Andrea Ludwig, Carsten Spisla, Michael Sswat, Paul Stange, Jan Taucher
更新时间: 2018-11-21
摘要: Ocean acidification, the change in seawater carbonate chemistry due to the uptake of anthropogenic CO 2 , affects the physiology of marine organisms in multiple ways 1. Diverse competitive and trophic interactions transform the metabolic responses to changes in community composition, seasonal succession and potentially geographical distribution of species. The health of ocean ecosystems depends on whether basic biotic functions are maintained, ecosystem engineers and keystone species are retained, and the spread of nuisance species is avoided 2. Here, we show in a field experiment that the toxic microalga Vicicitus globosus has a selective advantage under ocean acidification, increasing its abundance in natural plankton communities at CO 2 levels higher than 600 µatm and developing blooms above 800 µatm CO 2. The mass development of V. globosus has had a dramatic impact on the plankton community, preventing the development of the micro-and mesozooplankton communities, thereby disrupting trophic transfer of primary produced organic matter. This has prolonged the residence of particulate matter in the water column and caused a strong decline in export flux. Considering its wide geographical distribution and confirmed role in fish kills 3 , the proliferation of V. globosus under the IPCC 4 CO 2 emission representative concentration pathway (RCP4.5 to RCP8.5) scenarios may pose an emergent threat to coastal communities, aquaculture and fisheries.

28091. 题目: Mineral Identity, Natural Organic Matter, and Repeated Contaminant Exposures do not Affect the Carbon and Nitrogen Isotope Fractionation of 2,4-Dinitroanisole during Abiotic Reduction
文章编号: N18112109
期刊: Environmental Science: Processes & Impacts
作者: Matthew J Berens, Bridget Ulrich, Jennifer H. Strehlau, Thomas Hofstetter, William Arnold
更新时间: 2018-11-21
摘要: The recent development of insensitive munitions, such as 2,4-dinitroanisole (DNAN), as components of military explosives has generated concern for potential subsurface contamination and created a need to fully characterize their transformation processes. Compound specific isotope analysis (CSIA) has proven to be a useful means of assessing transformation pathways according to characteristic stable isotope fractionation patterns. The C and N isotope fractionation of DNAN associated with abiotic and enzymatic hydrolysis was recently assessed. The extent to which DNAN isotope fractionation will be affected by other potentially competing transformation pathways known for nitroaromatic compounds (e.g., reduction) and if previous knowledge can be extrapolated to other environmental matrices remains to be understood. Here, we investigated the C and N isotope fractionation and reaction rate constants of DNAN during abiotic reduction mediated by mineral-associated Fe(II) species as a function of mineral type, natural organic matter presence, and repeated exposures to DNAN. Though rate constants varied, N and C apparent kinetic isotope effects (AKIEs) remained consistent across all experiments (averaged values of ¹⁵N-AKIE = 1.0317 ± 0.0064 and ¹³C-AKIE = 1.0008 ± 0.0005) and revealed significant ¹⁵N- and minimal ¹³C- enrichment in agreement with previous work on nitroaromatic compounds. Moreover, the observed fractionation was clearly distinct from trends for abiotic and enzymatic hydrolysis. This study provides a strengthened basis for the use of compound specific isotope analysis as a robust tool for monitoring DNAN degradation in complex environmental matrices as a component of future remediation efforts.

28092. 题目: δ15N patterns in three subtropical estuaries show switch from nitrogen “reactors” to “pipes” with increasing degradation
文章编号: N18112108
期刊: Limnology and Oceanography
作者: Naomi S. Wells, Bradley D. Eyre
更新时间: 2018-11-21
摘要: Ongoing alterations to estuaries by inland agricultural intensification and coastal development could affect their capacity to regulate the flux of excess terrestrial nitrogen (N) to the coastal ocean. Here, a new multiform δ¹⁵N metric was developed to measure how “pristine,” moderately impacted, and highly degraded estuaries recycle (assimilation, mineralization) and remove (denitrification, anaerobic ammonium oxidation) N. Organic (dissolved and particulate, δ¹⁵N and δ¹³C) and inorganic (nitrate and ammonium, δ¹⁵N and δ¹⁸O) N forms were measured over the salinity gradient in the wet and dry season in subtropical estuaries receiving increasing terrestrial N loads (pristine: 16 kg N d⁻¹, moderate: 150 kg N d⁻¹, degraded: 630 kg N d⁻¹). The difference in the inorganic vs. organic pool δ¹⁵N composition increased between the pristine (0 ± 2‰), moderate (10 ± 6‰), and degraded (20 ± 8‰) systems, indicating that N recycling decreased as degradation increased. The N₂O concentrations, NO₃⁻ dual isotope values, and offsets between “measured” and “mixing expected” δ¹⁵N values further revealed that microbial processes removed up to 30% of the N load entering the moderately degraded estuary, but only 9% in the highly degraded estuary. Hydrologic differences (depth and flushing times [FTs]) could not fully explain these shifts in N fate between the estuaries and seasons, which instead aligned with nonlinear increases in phytoplankton biomass and light penetration with increasing N loads. These isotopic indicators provide direct evidence that estuaries switch from “reactors” that assimilate and remove terrestrial N to “pipes” that transport N directly to sea as degradation increases.

28093. 题目: Effects of elevated CO2 and phytoplankton-derived organic matter on the metabolism of bacterial communities from coastal waters
文章编号: N18112107
期刊: Biogeosciences
作者: Antonio Fuentes-Lema, Henar Sanleón-Bartolomé, Luis M. Lubián, and Cristina Sobrino
更新时间: 2018-11-21
摘要: Microcosm experiments to assess the bacterioplankton's response to phytoplankton-derived organic matter obtained under current and future ocean CO₂ levels were performed. Surface seawater enriched with inorganic nutrients was bubbled for 8 days with air (current CO₂ scenario) or with a 1000ppm CO₂ air mixture (future CO₂ scenario) under solar radiation. The organic matter produced under the current and future CO₂ scenarios was subsequently used as an inoculum. Triplicate 12L flasks filled with 1.2µm of filtered natural seawater enriched with the organic matter inocula were incubated in the dark for 8 days under CO₂ conditions simulating current and future CO₂ scenarios, to study the bacterial response. The acidification of the media increased bacterial respiration at the beginning of the experiment, while the addition of the organic matter produced under future levels of CO₂ was related to changes in bacterial production and abundance. This resulted in a 67% increase in the integrated bacterial respiration under future CO₂ conditions compared to present CO₂ conditions and 41% higher integrated bacterial abundance with the addition of the acidified organic matter compared to samples with the addition of non acidified organic matter. This study demonstrates that the increase in atmospheric CO₂ levels can impact bacterioplankton metabolism directly, by changes in the respiration rate, and indirectly, by changes on the organic matter, which affected bacterial production and abundance.
图文摘要:

28094. 题目: Biochar amendment improves crop production in problem soils: A review
文章编号: N18112106
期刊: Journal of Environmental Management
作者: Haowei Yu, Weixin Zou, Jianjun Chen, Hao Chen, Zebin Yu, Jun Huang, Haoru Tang, Xiangying Wei, Bin Gao
更新时间: 2018-11-21
摘要: Problem soils are referred to as those with poor physical, chemical, and biological properties that inhibit or prevent plant growth. These poor properties may be a result of soil formation processes but are largely due to inappropriate farming practices or anthropogenic pollution. The world has lost a third of its arable land due to erosion and pollution in the past 40 years. Thus, there is an urgent need for improving and remediating problem soils. As a novel multifunctional carbon material, biochar has been widely used as a soil amendment for improving soil quality. Previous reviews have summarized the characteristics of biochar, the interactions with various soil contaminants, and the effects on soil quality, soil productivity, and carbon sequestration. Relatively limited attention has been focused on the effects of biochar amendment on plant growth in problem soils. As a result, a comprehensive review of literature in the Web of Science was conducted with a focus on the effects of biochar amendment on plant growth in problems soils. The review is intended to present an overview about problem soils, biochars as functional materials for soil amendment, how amended biochars interact with soils, soil microbes, and plant roots in remediation of problem soil and improve plant growth. Additionally, existing knowledge gaps and future directions are discussed. Information gathered from this review suggests that biochar amendment is a viable way of improving the quality of problem soils and enhancing crop production. It is anticipated that further research on biochar amendment will increase our understanding on the interactions of biochar with components of problem soils, speed up our effort on soil remediation, and improve crop production in problem soils.

28095. 题目: The synthesis of heterogeneous Fenton-like catalyst using sewage sludge biochar and its application for ciprofloxacin degradation
文章编号: N18112105
期刊: Science of The Total Environment
作者: Jie Li, Lanjia Pan, Guangwei Yu, Shengyu Xie, Chunxing Li, Dengguo Lai, Zhiwei Li, Futian You, Yin Wang
更新时间: 2018-11-21
摘要: The terminal utilization of sewage sludge biochar (SSB) is nonnegligible and significant for sewage sludge (SS) treatment by pyrolysis. In this paper, a novel low-cost recyclable sludge biochar catalyst (SBC) that can be employed as a heterogeneous Fenton-like catalyst was prepared using SSB from SS pyrolysis in a pilot-scale platform for ciprofloxacin (CIP) degradation. The fabricated SBC was analyzed to characterize its surface micrographs, pore structures, and chemical composition. The catalytic effect of SBC on CIP degradation was also explored to determine the feasibility of using SBC to remove aquatic organic contaminants, and its degradation mechanism and pathway were also discussed. SBC can effectively remove CIP by adsorption and enhance the degradation of CIP by its catalytic effect. >80% of the CIP was removed at pH 4.0, and the antimicrobial activity of the resulting products was considerably reduced. The possible degradation mechanism is associated with the synergetic effect of adsorption and oxidative degradation. Oxidizing radical was generated from H₂O₂ by the activation of Fe²⁺ and Fe³⁺, which released from SBC, and HO was the dominant radical in CIP degradation. Piperazine ring cleavage, pyridine cleavage and hydroxylation, F/OH substitution, and defluorination were the dominant degradation pathways. The heavy metal risk assessment showed that SBC exhibits low environmental and ecological risk. This study provides a prospective method for high-value utilization of SSB and a novel and potentially low-cost catalyst for CIP removal from aqueous environments, which is significant for the terminal disposal of SS.
图文摘要:

28096. 题目: Combination of self-organizing map and parallel factor analysis to characterize the evolution of fluorescent dissolved organic matter in a full-scale landfill leachate treatment plant
文章编号: N18112104
期刊: Science of The Total Environment
作者: Xiaofang Yang, Liao Meng, Fangang Meng
更新时间: 2018-11-21
摘要: The dissolved organic matter (DOM) characterization in a full-scale landfill leachate treatment plant is of great importance for the design and operation of treatment processes. In this study, the long-term removal behaviors of DOM during landfill leachate treatment were explored using excitation emission matrix fluorescence spectroscopy (EEMs) coupled with parallel factor analysis (PARAFAC) and self-organizing map (SOM). Results indicated that the application of combining PARAFAC and SOM on EEMs analysis effectively characterized long-term removal behaviors of DOM during leachate treatment. The DOM in raw leachate was dominated by humic substances, while its composition exhibited significant seasonal differences. A large proportion of protein-like fluorescent dissolved organic matter (FDOM) and bulk DOM were removed within membrane bioreactor (MBR) system. Meanwhile the humic-like FDOM removal capacity in nanofiltration (NF) process was well comparable with those in the MBR system owing to the bio-recalcitrant nature of humic substances. The protein-like FDOM and bulk DOM were removed synchronously in both the process of MBR and NF. Moreover, samples distribution exhibited obvious differences among NF concentrate samples. In general, the performance of MBR-NF treatment for landfill leachate displayed reasonable stability in DOM removal irrespective of seasonal variations. This study enhanced our understanding of EEMs application in characterizing leachate-derived DOM composition and has potential implications for the associated monitoring investigations in engineered systems.
图文摘要:

28097. 题目: Kinetics and modeling of artificial sweeteners degradation in wastewater by the UV/persulfate process
文章编号: N18112103
期刊: Water Research
作者: Yingying Fu, Gang Wu, Jinju Geng, Juechun Li, Shengnan Li, Hongqiang Ren
更新时间: 2018-11-21
摘要: The frequent detection of artificial sweeteners (ASs) in wastewater and surface water gives rise to concerns about their removal, Acesulfame (ACE) and sucralose (SUC) are two ASs that are difficult to remove. The ultraviolet/persulfate (UV/PS) advanced oxidation technology (AOT) is being considered as an effective process for the degradation of micropollutants in wastewater. However, the study of the degradation of ASs in real wastewater by the UV/PS is minimal. This study investigated the kinetics and modeling of ACE and SUC degradation in wastewater by the UV/PS process. Both ACE and SUC could be degraded effectively using this process. The degradation of ACE was mainly attributed to UV photolysis (51%), HO^∙ (26%) and SO₄^∙- (16%), while that of SUC was mainly attributed to HO^∙ (68%) and SO₄^∙- (27%). The second-order rate constants of ASs with SO₄^∙- were significantly lower than that with HO^∙. Three major transformation products (TPs) of ACE and four major TPs of SUC were identified. Additionally, the effects and mechanisms of the water matrices, such as HCO₃^-, Cl^-, NO₃^- and natural organic matter (NOM), on ASs degradation were investigated through response surface methodology (RSM). NOM and Cl^- significantly inhibited the degradation of ACE in the UV/PS system, whereas NOM and HCO₃^- played a main inhibition role on the degradation of SUC. A water matrices parameter model for predicting ASs degradation in real wastewater was established by RSM for the first time, and the removal of ACE and SUC was well predicted by the model.
图文摘要:

28098. 题目: Impact of rheological properties of substrate on anaerobic digestion and digestate dewaterability: New insights through rheological and physico-chemical interaction
文章编号: N18112102
期刊: Water Research
作者: S. Miryahyaei, K. Olinga, F.A.Abdul Muthalib, T. Das, M.S.Ab Aziz, M. Othman, J.C. Baudez, D. Batstone, N. Eshtiaghi
更新时间: 2018-11-21
摘要: Mesophilic batch anaerobic digesters fed by different substrates were set up to identify the role of substrate rheology in anaerobic digestion performance while operating below the toxic level. Five substrates of different rheological behaviour but at the same amount of organic matters were prepared by addition of different amount of an inert material (0, 0.03, 0.07, 0.11, and 0.20 g) per g of waste activated sludge (WAS). To gain a comprehensive insight, the interactive relationship between substrate rheology, physico-chemical properties and biogas production as well as digestate dewaterability was investigated. The results proved that better access of microorganisms to organic matters improved the digester performance and led to 19.29% and 12.5% increase in biogas yield and VS removal efficiency, respectively. Moreover, the statistical analysis showed that consistency index and loss modulus of sludge could be employed as promising indications for biogas yield while yield stress could predict dewaterability of digestate as far as the other physico-chemical properties remained unchanged. During digestion measurement of consistency index and loss modulus of digestate could be performed as a reliable tool to monitor biogas production.
图文摘要:

28099. 题目: Environmental factors controlling arsenic mobilization from sandy shallow coastal aquifer sediments in the Mannar Island, Sri Lanka
文章编号: N18112101
期刊: Applied Geochemistry
作者: Udara Amarathunga, Saranga Diyabalanage, U.G.C. Bandara, Rohana Chandrajith
更新时间: 2018-11-21
摘要: Elevated levels of arsenic (As) have been reported in groundwater from sandy aquifer systems in the Mannar Island, located in the northwest of Sri Lanka. As a result of serious health concerns, this study aims to investigate groundwater aquifers in order to trace the different As sources and mechanisms involved in its release from aquifer sediments. A piezometer was constructed in an As contaminated area and groundwater and sediment samples were retrieved from the well for further analyses. Water samples were also collected from wells in the vicinity of the piezometer and As species and other trace elements were determined using voltammetric and ICP-MS methods. Groundwater samples showed total As concentrations ranging from 6.5 μg/L up to 43.8 μg/L. All wells with high As concentrations (>25 μg/L) showed near-neutral pH conditions. Fe and Ba concentrations in groundwater indicated their coexistence with As. Among the different elements detected in sediments, Na, K, Ca, Mg, Al, Fe, As, Ba and organic matter content showed an increasing trend towards the groundwater table. Sediment analysis depicted very high affinities of both As and Fe, particularly in the finer grain size. Desorption experiments indicated that most effective release of As occurred between pH 5.0 and 6.0, the average release of As being 61 mg/L and 54 mg/L per kg of aquifer material, respectively. The FTIR analyses indicated As-bearing metal-OH complexes in sediment coatings. When rain water infiltrates the aquifer, oxygen becomes depleted at or near the surface due to the decay of organic matter, and hence, dissolution of carbonate minerals may increase with subsequent increase of groundwater pH to near-neutral levels. Such conditions are favored for mobilizing As into groundwater from As-adsorbed Fe-oxyanions in sediments.
图文摘要:

28100. 题目: Microbial formation of stable soil carbon is more efficient from belowground than aboveground input
文章编号: N18112008
期刊: Nature Geoscience
作者: Noah W. Sokol, Mark A. Bradford
更新时间: 2018-11-20
摘要: The relative contributions of aboveground versus belowground plant carbon inputs to the stable soil organic carbon pool are the subject of much debate—with direct implications for how the carbon cycle is modelled and managed. The belowground rhizosphere pathway (that is, carbon exiting the living root) is theorized to form stable soil carbon more efficiently than the aboveground pathway. However, while several mechanisms have been invoked to explain this efficiency, few have been empirically tested or quantified. Here, we use soil microcosms with standardized carbon inputs to investigate three posited mechanisms that differentiate aboveground from belowground input pathways of dissolved organic carbon—through the microbial biomass—to the mineral-stabilized soil organic carbon pool: (1) the physical distance travelled, (2) the microbial abundance in the region in which a carbon compound enters (that is, rhizosphere versus bulk soil) and (3) the frequency and volume of carbon delivery (that is, infrequent ‘pulse’ versus frequent ‘drip’). We demonstrate that through the microbial formation pathway, belowground inputs form mineral-stabilized soil carbon more efficiently than aboveground inputs, partly due to the greater efficiency of formation by the rhizosphere microbial community relative to the bulk soil community. However, we show that because the bulk soil has greater capacity to form mineral-stabilized soil carbon due to its greater overall volume, the relative contributions of aboveground versus belowground carbon inputs depend strongly on the ratio of rhizosphere to bulk soil.