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22661. 题目: Statistical correlation of ecotoxicity and water quality parameters in slaughterhouse wastewater
文章编号: N19051402
期刊: Environmental Geochemistry and Health
作者: Hee-Jun Kim, Donggwan Lee, Chan-Hee Won, Hyun-Woo Kim
更新时间: 2019-05-14
摘要: The major causes of toxicity in slaughterhouse wastewater are identified by analyzing the relationship between representative pollutants and the acute toxicity of Daphnia magna. Experimental results demonstrate that organic matters are strongly associated with the acute toxicity. Among many organic pollutants, proteins and carbohydrates were found to be the main toxicity inducers that cause metabolic transformation of D. magna. Statistical correlation between biodegradable soluble organics and the acute toxicity further explains how principal pollutants play potential toxin roles. Also, this study verifies that the variations of biochemical oxygen demand over total chemical oxygen demand (BOD TCOD−1) as well as total organic carbon over total carbon (TOC TC−1) can be indirect indicators explaining the acute toxicity of D. magna because the removal of non-degradable and non-soluble organic matters is connected to the toxicity removal. Overall, these results provide how the acute toxicity of D. magna is attributed to pollutants and what is the potential source of threats to society in slaughterhouse wastewater.

22662. 题目: CO2 and CH4 fluxes are decoupled from organic carbon loss in drying reservoir sediments
文章编号: N19051401
期刊: Biogeosciences
作者: Tricia Light, Núria Catalán, Santiago Giralt, and Rafael Marcé
更新时间: 2019-05-14
摘要: Reservoirs are a prominent feature of the current global hydrological landscape, and their sediments are the site of extensive organic carbon burial. Meanwhile, reservoirs frequently go dry due to drought and/or water management decisions. Nonetheless, the fate of organic carbon buried in reservoir sediments upon drying is largely unknown. Here, we conducted a 45-day-long laboratory incubation of sediment cores collected from a western Mediterranean reservoir to investigate carbon dynamics in drying sediment. Drying sediment cores emitted more CO₂ over the course of the incubation than sediment cores incubated with overlaying water (206.7 ± 47.9 vs. 69.2 ± 18.1 mmol CO2 m⁻² day⁻¹, mean ± SE). Organic carbon content at the end of the incubation was lower in drying cores, which suggests that this higher CO₂ efflux was due to organic carbon mineralization. However, the apparent rate of organic C reduction in the drying sediments (568.6 ± 247.2 mmol CO₂ m⁻² day⁻¹, mean ± SE) was higher than C emission. Meanwhile, sediment cores collected from a reservoir area that had already been exposed for 2+ years displayed net CO₂ influx from the atmosphere to the sediment (−136.0 ± 27.5 mmol CO₂ m⁻² day⁻¹, mean ± SE) during the incubation period. Sediment mineralogy suggests that this CO₂ influx was caused by a relative increase in calcium carbonate chemical weathering. Thus, we found that while organic carbon decomposition in newly dry reservoir sediment causes measurable organic carbon loss and carbon gas emissions to the atmosphere, other processes can offset these emissions on short time frames and compromise the use of carbon emissions as a proxy for organic carbon mineralization in drying sediments.

22663. 题目: Effect of grassland degradation on aggregate‐associated soil organic carbon of alpine grassland ecosystems in Qinghai‐Tibetan Plateau
文章编号: N19051303
期刊: European Journal of Soil Science
作者: Shikui Dong, Jing Zhang, Yuanyuan Li, Shiliang Liu, Qugnaming Dong, Huakun Zhou, Jane Yeomans, Yv Li, Shuai Li, Xiaoxia Gao
更新时间: 2019-05-13
摘要: One of the important mechanisms for the stabilization of soil organic carbon (SOC) is its spatial inaccessibility for microbial biodegradation within soil aggregates. However, little has been documented regarding soil aggregate stability with grassland degradation in the alpine region of Qinghai‐Tibetan Plateau (QTP). In this study, we used physical and density fractions to elucidate the mechanisms of differences in SOC in non‐degraded and degraded grasslands of two grassland biomes, alpine meadow and alpine steppe in the QTP. There were considerable differences between non‐degraded and degraded grasslands for the soil physical and chemical properties, aggregate distribution and aggregate‐SOC content. The non‐degraded alpine meadow (AMND) had the largest value among all the alpine grasslands for the SOC content of the microaggregate fraction, with values of 31.83 g kg^–1. The degraded grasslands showed significantly larger SOC content of macroaggregates than non‐degraded grasslands. The degraded alpine steppe (ASD) had the largest SOC content, with the values of 25.51 g kg^–1. The aggregate distribution of the macroaggregate, microaggregate and free silt+clay was consistent with the variation in SOC content of these three aggregate fractions. The fine intra‐aggregate particulate organic matter (fiPOM) content was significantly less in degraded grasslands, indicating that grassland degradation might have disrupted the fiPOM‐C. The increase in CO₂ emissions was related to the destruction of soil aggregates in the alpine grasslands of the QTP.

22664. 题目: Soil organic matter and microbial community responses to semiarid croplands and grasslands management
文章编号: N19051302
期刊: Applied Soil Ecology
作者: Rajan Ghimire, Vesh R. Thapa, Amanda Cano, Veronica Acosta-Martinez
更新时间: 2019-05-13
摘要: Livestock integration in cropping systems and conversion of croplands into grazing lands has been increasingly considered to improve agricultural sustainability, yet their roles in soil health and resilience are not clear due to the complex interactions of soil, climate, and agricultural systems. A study was conducted to evaluate the effects of cropland and grassland management systems on soil organic carbon (SOC) and total nitrogen (N) across the soil profile (0–20, 20–40, 40–60, and 60–80 cm) and microbial community size, structure, and activity in the soil surface (0–20 cm) as indicators of soil health. Cropland systems compared included conventional-tilled winter-grazed cropland (CTGC) and no-tilled and strip-tilled croplands (NTC and STC) without livestock grazing. Grassland systems included grazed grassland (GGL) and ungrazed grassland (UGL). Grassland soils accumulated 18% greater SOC and 13% greater total N than cropland soils in the 0–80 cm profile. Microbial community size (sum of ester-linked fatty acid methyl esters [El-FAME]) in the surface 0–20 cm was 90% greater, and enzyme activities were 131–155% greater in the grasslands than in the croplands. Within grasslands, cattle (Bos taurus) grazing increased microbial community size by approximately 42%, which was mainly due to greater fatty acid methyl esters (FAME) markers for gram-positive bacteria (51%) and Actinobacteria (73%). Grazed cropland had 95% more β‑glucosaminidase activity than ungrazed croplands. This study suggests light grazing and grassland restoration has potential to improve soil health and resilience through an increase in SOC and microbial community responses related to nutrient cycling.

22665. 题目: Carbon sequestration in soil amended with anaerobic digested matter
文章编号: N19051301
期刊: Soil and Tillage Research
作者: R. Béghin-Tanneau, F. Guérin, M. Guiresse, D. Kleiber, J.D Scheiner
更新时间: 2019-05-13
摘要: Organic carbon (C) sequestration in agricultural soils is regarded as a mean to mitigate carbon dioxide (CO2) concentration increase in the atmosphere and to secure food production. Among other practices, exogenous organic matter (EOM) addition in soils is a way to sequestrate organic C. In this study, we compared the organic matter stability, carbon sequestration, soil respiration in soils amended with sucrose, silage EOM and anaerobic digested EOM. We used agricultural soils from a perennial pasture (C3 plants) and EOM from sugar cane and maize (C4 plants). The 13C natural abundance tracer technique has been used to separate SOM-derived and EOM-derived CO2 productions from soil in order to measure EOM stability and priming effects. Undigested-EOM addition did not lead to C sequestration due to a low stability of its organic matter and a positive priming effect that enhanced native SOM respiration. Digested-EOM addition in soil led to C sequestration due to inherent stability of EOM and to a negative priming effect which decreased native SOM respiration. We finally evaluated carbon balance of both direct incorporation of silage in soil and anaerobic digestion followed to incorporation of digestate. Our broad estimation shows that the use of digestate amendment not only favour carbon sequestration but also reduce CO2 emissions by 27% as compared to the incorporation of maize silage.

22666. 题目: Effect of Freezing–Thawing Cycle on Soil Active Organic Carbon Fractions and Enzyme Activities in the Wetland of Sanjiang Plain, Northeast China
文章编号: N19051206
期刊: Wetlands
作者: Fu Li, Shuying Zang, Yingnan Liu, Lan Li, Hongwei Ni
更新时间: 2019-05-12
摘要: To determine the response of soil active organic carbon fractions and enzyme activities to freezing-thawing cycles (FTCs), an FTC simulation experiment of Deyeuxia angustifolia wetland soil samples collected from Sanjiang Plain, Northeast China, were examined. The results showed that the water-extracted organic carbon (WEOC), microbial biomass carbon (MBC) concentration and three enzyme activities were affected by FTCs. FTCs increased WEOC concentration, and the small amplitude (0 °C ± 5 °C) and the low water content interaction had the maximum impact, which was nearly 9.0–70.4%, while the large amplitude and the low water content interaction had the minimum impact, which was about 3.6–50.7%. FTCs significantly decreased MBC concentration, amylase, invertase and catalase activities. During the large amplitude (0 °C ± 10 °C) and high water content interaction impacted heavily on MBC, which was approximately 4.2–41.45%. As the number of FTC increased, WEOC concentration increased followed by a gradually decline in contrast that MBC concentration and three enzyme activities showed an opposite tendency. There was a significant correlation between soil active organic carbon fractions and enzyme activities. In addition, negative correlation was observed between WEOC and MBC. This may suggested that increased WEOC by FTCs plays an important role in soil microbes.

22667. 题目: Mechanism study on the impacts of hydraulic alteration on fish habitat induced by spur dikes in a tidal reach
文章编号: N19051205
期刊: Ecological Engineering
作者: Ya Deng, Min-xiong Cao, Ai-xing Ma, Ying Hu, Liu-hong Chang
更新时间: 2019-05-12
摘要: Spur dikes have been utilized as channel regulation structures worldwide, especially in the upstream tidal reach of river estuary, where is a superexcellent habitat for resident fish or migratory fish during different life history stages. However, local hydraulic characters will be altered upon spur dikes establishment, resulting in several influence on fish habitat. The purpose of this paper was to reveal the impacts mechanism of spur dikes on fish habitat in a tidal reach through a comprehensive analysis based on some previous neglected aspects, such as fish physiological characters, hydraulic variations and essential factors alterations of the aquatic ecosystem. Hydraulic information around spur dikes was acquired through a 3D hydrodynamic model, and validations of tidal level, velocity and diversion ratio yielded a high accuracy. Turbulent rapid around spur dikes head and mild nearshore environment behind structures have some potentialities to become new spawning grounds, for fish spawning semi-pelagic eggs and fish laying adhesive eggs respectively. Benefitted from effective mixture of water during a tidal cycle, plenty of planktons and organic matters will be brought in and gradually enriched behind structures, thus a favorable feeding ground will appear there. Meanwhile, deflecting flow induced by spur dikes may cause some hazards for survival probability of migratory larval fish. It is drifted off the nearshore into the river middle, where is a higher turbulent intensity and less phytoplankton concentration. In summary, spur dikes possess tremendous ecological effects, i.e. enriching the eco-hydraulic diversity, not only as a velocity shelter. In addition, research result could afford a sufficient basis for environment conservations to restore aquatic ecosystem with spur dikes.
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22668. 题目: Improved sludge dewaterability by tannic acid conditioning: Temperature, thermodynamics and mechanism studies
文章编号: N19051204
期刊: Chemosphere
作者: Dongdong Ge, Haiping Yuan, Yanwen Shen, Wenrui Zhang, Nanwen Zhu
更新时间: 2019-05-12
摘要: Waste activated sludge (WAS), containing biological pathogens, chemical elements and high moisture (>99%), was generated continually from municipal sewage treatment plants. Sludge dewatering could diminish the volume of WAS and control the diffusion of environmental pollution efficiently. In this study, tannic acid (TA), as a plant-derived phenolic compound, was investigated for improving WAS dewaterability at different temperatures. Apparently, the WAS dewaterability was enhanced by TA conditioning in the range of 25–55 °C, but further increase in temperature did not significantly affect the dewatering. With the TA addition of 0.15 mmol/gTS (total solid) at 55 °C, the WAS dewaterability was improved by 84.5% decrease in capillary suction time (CST), 96.5% decrease in specific resistance of filtration (SRF), and 19.9% decrease in water content (Wc) of dewatered sludge cake. TA facilitated removing supernatant viscosity and protein of sludge EPS (extracellular polymeric substances), specifically with 88.9% and 75.0% protein removal of slime EPS (S-EPS) and loosely bound EPS (LB-EPS). Thermodynamics modeling revealed that the improved dewaterability was dominantly attributed to the hydrophobic bonding between TA and EPS proteins, which was strengthened with the increase in temperature. However, when the conditioning temperature exceeded 55 °C, thermal effect took place and accelerated the release of biopolymers into EPS and hence, counteracted the beneficial effect of TA conditioning to further improve WAS dewatering. The results offered not only the dewatering effectiveness and mechanism of TA conditioning, but also a potential approach of applying plant waste to treat WAS for the high dewaterability.
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22669. 题目: Elimination of trichloroanisoles by UV/H₂O₂: Kinetics, degradation mechanism, water matrix effects and toxicity assessment
文章编号: N19051203
期刊: Chemosphere
作者: Huanhuan Zhu, Ruibao Jia, Shaohua Sun, Guixue Feng, Mingquan Wang, Qinghua Zhao, Xiaodong Xin, Anran Zhou
更新时间: 2019-05-12
摘要: The elimination of 2,3,6-trichloroanisole (2,3,6-TCA), which produces a musty-earthy off-odor in water, by an ultraviolet (UV)/H₂O₂ process was assessed. The removal of 88.1% of 2,3,6-TCA in ultrapure water (UPW) was achieved using an initial 2,3,6-TCA concentration of 1 μg L⁻¹ (4.73 nM), a H₂O₂ concentration of 20 mg L⁻¹ (0.588 mM), a UV intensity of 1.44 mW cm⁻² and a pH of 8.2. The reaction was found to be pseudo first order with a rate constant (k_obs) of 0.0340 min⁻¹ Both the removal efficiency and k_obs increased significantly upon increasing the H₂O₂ concentration from 10 to 50 mg L⁻¹. The second order rate constant (k_{HO·,2,3,6-TCA}) in competition kinetic trials was determined to be 8.17 × 10⁷ M⁻¹s⁻¹. Degradation products generated during both the UV photolysis and UV/H₂O₂ treatment of 2,3,6-TCA solutions were analyzed using ultrahigh resolution gas chromatography/mass spectrometry, and the degradation mechanism was proposed. The toxicities of water solutions during both processes were assessed via a luminescence method in conjunction with Vibrio fischeri. The pH and Cl⁻, HCO₃⁻ and natural organic matter concentrations of the aqueous medium were all found to significantly affect the removal of 2,3,6-TCA. The degradation rates of trichloroanisoles (TCAs) in real-world water samples demonstrated that UV/H₂O₂ has significant potential with regard to controlling TCAs as pollutants in water.
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22670. 题目: Efficient removal of atrazine by iron-modified biochar loaded Acinetobacter lwoffii DNS32
文章编号: N19051202
期刊: Science of The Total Environment
作者: Yue Tao, Songbo Hu, Siyue Han, Hongtao Shi, Yang Yang, Hanxu Li, Yaqi Jiao, Qi Zhang, Modupe Sarah Akindolie, Mingyuan Ji, Zhaobo Chen, Ying Zhang
更新时间: 2019-05-12
摘要: In order to efficiently remove commonly used herbicide atrazine in farmland, an iron-modified biochar (FeMBC) was fabricated via chemical co-precipitation of Fe³⁺ onto corn stalks biochar. The composites of FeMBC and Acinetobacter lwoffii DNS32 (bFeMBC) effectively accelerated the degradation rate of atrazine (100 mg L⁻¹) in inorganic salt culture solution. TEM，XRD，XPS and FTIR were used to study the basic properties of the Materials. FeMBC promoted the formation of bacterial biofilm, -NH functional group on the surface of bacterial extracellular polymers (EPS) and FeMBC could interact with the aromatic ring of atrazine through Hbonding, which were conducive for microbial capture of atrazine. Meanwhile, the pores (2–10 μm) of FeMBC facilitated the passage of the DNS32 strain and the atrazine molecule, which contributed to the efficient capture and degradation of atrazine by DNS32 strain. BFeMBC amendment helped to maintain the bacterial diversity in the atrazine contaminated soil. The increase of rare bacteria (relative abundance of 0.01%–0.05%) richness plays a certain role in stabilizing nutrient cycling, thereby promoting microbial nutrient utilization activities and has the function of pollutant degradation. This may contribute to the digestion of atrazine and its intermediate metabolites，reducing the stress of microbial in atrazine contaminated soil. bFeMBC amendment may be a promising in situ remediation technique for soil atrazine contamination.
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22671. 题目: Degradation of triphenyl phosphate (TPhP) by CoFe₂O₄-activated peroxymonosulfate oxidation process: Kinetics, pathways, and mechanisms
文章编号: N19051201
期刊: Science of The Total Environment
作者: Qingyun Song, Yiping Feng, Zhu Wang, Guoguang Liu, Wenying Lv
更新时间: 2019-05-12
摘要: The aryl organophosphate flame retardant triphenyl phosphate (TPhP) has been frequently detected in environment and biota, and the potential risks of TPhP to aquatic organisms have also been demonstrated. The degradation of TPhP by CoFe₂O₄ activated peroxymonosulfate (PMS) was studied in this work. At initial pH of 7.0, 10 μM TPhP could be removed by 99.5% with 0.25 g/L CoFe₂O₄ and 0.5 mM PMS after 6 min oxidation, indicating the excellent performance of CoFe₂O₄ activated PMS process on the treatment of TPhP. The influence of PMS and CoFe₂O₄ dosage, initial pH, humic acid (HA), and anions (Cl⁻, NO₃⁻, and HCO₃⁻) on TPhP degradation were investigated systematically. Results showed that the degradation of TPhP was enhanced with increasing PMS concentrations from 0.1 to 1 mM, while it reduced as CoFe₂O₄ dosage increased. TPhP degradation efficiencies depended on solution pH with neutral pH showing the optimum degradation conditions. Recycling experiment indicated that the CoFe₂O₄ nanoparticles (NPs) possessed high potential for reusability. The radical identification experiments were performed and SO₄•⁻ was confirmed as the dominant radicals in TPhP degradation, and activation mechanism of PMS by CoFe₂O₄ NPs was hence explained. Humic acids (HA) (2–20 mg/L) as the representative organic natural matter existing in environment inhibited TPhP removal. Anions including Cl⁻, NO₃⁻, and HCO₃^– all reduced TPhP degradation. In addition, TPhP degradation products were identified by liquid chromatography-mass spectrometry, and the degradation pathways of TPhP were proposed accordingly.
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22672. 题目: The combined effects of nitrogen fertilizer, humic acid, and gypsum on yield-scaled greenhouse gas emissions from a coastal saline rice field
文章编号: N19051111
期刊: Environmental Science and Pollution Research
作者: Liying Sun, Yuchun Ma, Yinglie Liu, Jia Li, Junyin Deng, Xudong Rao, Yu Zhang
更新时间: 2019-05-11
摘要: In coastal saline rice fields, rice production shows high greenhouse gas (GHG) emissions but low nitrogen use efficiency (NUE). However, few studies have focused on the combined effects of nitrogen (N) fertilizer and soil ameliorants on GHG emissions. Thus, a field experiment was conducted to study the combined effects of N fertilizer, humic acid, and gypsum on the global warming potential (GWP), yield-scaled greenhouse gas intensity (GHGI), rice grain yield, and NUE in coastal saline rice fields in southeastern China. The experiment was conducted with eight treatments: N0, N1, N0H1, N1H1, N0G1, N1G1, N0H1G1, and N1H1G1. The codes N0, N1, H1, and G1 represented treatments without N (0 kg N ha⁻¹), with N (300 kg N ha⁻¹), with humic acid (0.6 t ha⁻¹), and with gypsum (0.6 t ha⁻¹), respectively. Compared with the treatments without N addition, the application of N fertilizer significantly increased N₂O emissions and grain yield by 41.9~130.6% and 32.8~57.5%, respectively, while significantly decreased the yield-scaled GHGI by 9.4~31.9%. Humic acid amendment significantly increased N₂O emissions and grain yield as compared with the treatments without humic acid. Gypsum addition had no significant effects on CH₄ and N₂O emissions, GWP, yield-scaled GHGI, and grain yield in relation to the treatments without gypsum. In addition, compared with the N1 treatment, the N1H1, N1G1, and N1H1G1 treatments increased the grain yield by 18.3% (p < 0.05), 2.3%, and 10.4%, and decreased yield-scaled GHGI by 9.6%, 20.5%, and 31.2% (p < 0.05), despite similar GWPs, respectively. Overall, the N1H1 and N1H1G1 treatments are the appropriate fertilizer management to realize high yield together with low environmental impacts in coastal saline rice fields in China.

22673. 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.

22674. 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.

22675. 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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22676. 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.

22677. 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.

22678. 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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22679. 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.

22680. 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.