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24681. 题目: Effects of fish culture on particulate organic matter in a reservoir-type river as revealed by absorption spectroscopy and fluorescence EEM-PARAFAC
文章编号: N19090610
期刊: Chemosphere
作者: Hui Wang, Yonghao Wang, Wan-E Zhuang, Wei Chen, Weixin Shi, Zhuoyi Zhu, Liyang Yang
更新时间: 2019-09-06
摘要: Dam construction and fish culture can change the biogeochemical processes in river, yet their impact on the spectral properties of particulate organic matter (POM) remains to be studied. This was investigated in a reservoir-type river (Minjiang river, SE China) using absorption spectroscopy and fluorescence excitation-emission matrices-parallel factor analysis (EEMs-PARAFAC). Five fluorescent components were identified from POM with PARAFAC. Four components C1–C4 were affected by the seasonal variations of rainfall and runoff, indicating the influences of hydrological condition and terrestrial inputs. The Chlorophyll a concentration (Chl a) correlated significantly with the humic-like C3 (p < 0.05) and the protein-like C4 (p < 0.01), indicating phytoplankton was an important source of C3 and C4. The Chl a and fluorescence intensities of C3–C4 were higher in the fish culture zones than in other areas, and the absorption coefficient a300 and C1–C4 were lower downstream the dam. These results indicated that fish farming in the reservoir probably promoted the production of POM. The a300 and C1 per unit mass of suspended particulate matter (a300/TSM and C1/TSM) correlated significantly with the median particle size (p < 0.01), which might be related to the contribution of micro-phytoplankton. The absorption spectra of POM showed a shoulder peak at ∼280 nm, and its intensity correlated significantly and positively with Chl a (p < 0.01). These results indicated that the peak was probably derived from phytoplankton production. Our results have implications for better understanding the influences of human activities on the dynamics of river POM.
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24682. 题目: Composition of the dissolved organic matter produced during in situ burning of spilled oil
文章编号: N19090609
期刊: Organic Geochemistry
作者: Aprami Jaggi, Jagoš R. Radović, Lloyd R. Snowdon, Stephen R. Larter, Thomas B.P. Oldenburg
更新时间: 2019-09-06
摘要: In situ burning is often used as a response method for oil slicks in the marine environment. This process however forms viscous tar-like residues that either float on the surface or sink through the water column, introducing organic species into the water phase. The interaction of this burn residue with the water phase also introduces dissolved organics into the water column. In this study, we conducted laboratory-scale experiments to characterize and compare the organic species entering the water phase from the petrogenic (fresh oil) and pyrogenic (burnt oil) input during oil spills. The oil and water-soluble organics were characterized using ultra-high-resolution mass spectrometry (FTICR-MS). The results show that burning strongly increases concentrations of oil-related constituents entering the water phase, due to transformation reactions producing oxidized organic species with higher water solubility. The pyrogenic water-soluble organics also showed a higher percentage of unsaturated compounds relative to the petrogenic fraction. The effect of these highly unsaturated and oxygenated organic species on oil spill fate and their ecosystem impacts is currently unknown.
24683. 题目: Sediment properties of lithologic units and their correlation within the lower delta plain of the Nakdong River Delta, southeast Korea
文章编号: N19090608
期刊: Quaternary International
作者: Boo-Keun Khim, Seungwon Shin, Jin Cheul Kim, Hiroyuki Takata, Sangmin Hyun, Daekyo Cheong
更新时间: 2019-09-06
摘要: Multi-proxy sediment properties reveal that three cores (ND-01, ND-02, and ND-03) from the lower delta plain of the Nakdong River Delta, southeast Korea, are characterized by the same stratigraphic lithologic successions consisting of a upper sand unit (10–15 m thick and <1 ka), a middle mud unit (∼20 m thick and 1–9 ka), a lower sand unit (6–9 m thick and 9–10 ka), and a lower mud unit (10–15 m thick and >10 ka) overlying weathered gravelly fluvial sediments and weathered bedrock. The sediment properties of each lithologic unit are controlled by the balance between the marine influence from Holocene sea level rise and the freshwater influence from Nakdong River discharge. In particular, the middle mud unit is characterized by distinct peaks in CaCO3 content, P/T ratios (the ratio of planktonic foraminifera to the sum of benthic and planktonic foraminifera), total organic carbon and total nitrogen contents, and δ13Corg values at 7–8 ka, which indicates that the maximum marine forcing during the sea level rising and the greatest influence of the Tsushima Warm Current during the evolution of the river-mouth coastal depositional system from an estuarine to a deltaic environment. Although the vertical stacking of lithologic successions is stratigraphically consistent within the lower delta plain, the precise temporal evaluation and comprehensive depositional evolution in the Nakdong River Delta including the upper delta plain and the prodelta zones remain a topic of future investigation.
24684. 题目: Past climate changes over South Korea during MIS3 and MIS1 and their links to regional and global climate changes
文章编号: N19090607
期刊: Quaternary International
作者: Sujeong Park, Jaesoo Lim, Hyoun Soo Lim
更新时间: 2019-09-06
摘要: To test past climate change in central Korea in terms of latitudinal differences over the Korean Peninsula, we reconstructed relative abundances between C3 and C4 plants in Hanam area based on sedimentary total organic carbon isotope values (δ13CTOC) of a 2.8 m long trench in an archeological site and compared these data with climate changes at different latitudes of Korea. During marine isotope stage 3 (MIS3) corresponding to past 60,000–25,000 years, the millennial-timescale fluctuations of the δ13CTOC values in Hanam were more similar to those in Hongcheon located in the inner mountain area of central Korea than those in Cheollipo area in west coast of Korea. Periods with significantly decreased δ13CTOC values representing decreased C4 plants under wetter climates in these two inland areas are comparable with millennial-timescale Dansgaard–Oeschger (D-O) warming events recorded in Greenland ice cores, suggesting strong climatic teleconnection between East Asia and subpolar areas during the last glacial period. During MIS1 (Holocene), the changes in vegetation and climate in Hanam have been influenced by the long-term summer monsoon changes. Regarding past latitudinal change in aridity or humidity over Korea, during the middle Holocene, δ13CTOC values in areas of central South Korea gradually decreased, suggesting moving to a more humid climate. This is contrary to the increasing δ13CTOC values in southern South Korea indicating more dry climates. Furthermore, it is likely that there were two severe dry climates at different times at different latitudes (1000 cal BP in Hanam in northern South Korea and 2500 cal BP in Geoje in southern South Korea), suggesting possible different climate changes at millennial timescales over Korea.
24685. 题目: Field demonstration of enhanced removal of chlorinated solvents in groundwater using biochar-supported nanoscale zero-valent iron
文章编号: N19090606
期刊: Science of The Total Environment
作者: Linbo Qian, Yun Chen, Da Ouyang, Wenying Zhang, Lu Han, Jingchun Yan, Petr Kvapil, Mengfang Chen
更新时间: 2019-09-06
摘要: The application of biochar-supported nanoscale zero-valent iron (biochar-nZVI) was successfully implemented in a field demonstration for the first time. To overcome the significant shortcomings of nZVI agglomeration for in-situ groundwater remediation, biochar-nZVI was injected into groundwater using direct-push and water pressure driven packer techniques for a site impacted by chlorinated solvents in the North China Plain. The field demonstration comprising two-step injections was implemented to demonstrate the effectiveness of nZVI and biochar-nZVI respectively. The outcome of the demonstration revealed a sharp reduction of contaminant concentrations of chlorinated solvents in 24 h following the first injection of nZVI, but the rebound of the concentrations of these contaminants in groundwater has occurred within the next two weeks. However, application of biochar-nZVI greatly enhanced the removal of chlorinated solvents in groundwater over the longer period of 42 days. The enhanced removal of chlorinated solvents in groundwater by biochar-nZVI is mainly attributed to the synergistic effects of adsorption and reduction. The adsorption by biochar significantly reduced the level of chlorinated solvents in groundwater. Overall increases in ferrous iron and chloride concentrations after the injections indicated that the reduction has occurred during the removal of chlorinated solvents in groundwater. In summary, biochar-supported nZVI could be potentially used for the effective remediation of chlorinated solvents in groundwater.
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24686. 题目: Enhanced removal of hexavalent chromium by engineered biochar composite fabricated from phosphogypsum and distillers grains
文章编号: N19090605
期刊: Science of The Total Environment
作者: Guoqi Lian, Bing Wang, Xinqing Lee, Ling Li, Taoze Liu, Wenqiang Lyu
更新时间: 2019-09-06
摘要: Two kinds of industrial wastes (distillers grains and phosphogypsum) were used as raw materials to produce a new biochar composite for Cr(VI) removal in water. The influencing factors including pyrolysis temperature, dosage, initial solution pH as well as contacting time were explored. The adsorption kinetics, isotherms, and thermodynamics of two biochars were conducted. The results show that the adsorption of Cr(VI) by biochar is related to pH. The ideal pH was 3.0 and the adsorbed Cr(VI) decreases as the pH increases. The Cr(VI) adsorption process conformed to the pseudo-second-order equation. Phosphogypsum modified (PM)-biochar is well described by the Freundlich model. The maximum adsorption capacities of distillers grains (DG)-biochar and PM-biochar on Cr(VI) were 63.1 and 157.9 mg g−1, respectively. The thermodynamic analysis indicates that the Cr(VI) adsorption occurs spontaneously which is an endothermic process. This study provided an alternative way for Cr(VI) removal from water.
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24687. 题目: Enhanced thallium(I) removal from wastewater using hypochlorite oxidation coupled with magnetite-based biochar adsorption
文章编号: N19090604
期刊: Science of The Total Environment
作者: Huosheng Li, Jingfang Xiong, Gaosheng Zhang, Aiping Liang, Jianyou Long, Tangfu Xiao, Yongheng Chen, Ping Zhang, Dandan Liao, Lianhua Lin, Hongguo Zhang
更新时间: 2019-09-06
摘要: The development of efficient and regenerable adsorbent coupled with advanced oxidation for enhanced thallium (Tl) removal has been a recent focus on wastewater treatment. In this study, a magnetite-based biochar derived from watermelon rinds was synthesized and used as a sustainable adsorbent and catalyst for hypochlorite oxidation and removal of Tl(I) from wastewater. The addition of hypochlorite substantially enhanced the Tl(I) removal under normal pH range (6–9). Maximum Tl adsorption capacity of 1123 mg/g was achieved, which is 12.3% higher than the highest value previously reported. The magnetic biochar can be regenerated using 0.1 mol/L HNO3 solution for elution in only 5 min, with a Tl desorption efficiency of 78.9%. The Tl removal efficiency was constantly higher than 98.5% during five consecutive recycle tests, indicating the effective reuse performance of the adsorbent. Oxidation, surface precipitation, pore retention and surface complexation were the main mechanisms for Tl(I) removal. The re-dissolution of Tl compounds and ion exchange of Tl cations with proton were the main mechanisms for adsorbent regeneration. Given the fast oxidation rate, high adsorption capacity, steady reusability and facile separability, this magnetic biochar-hypochlorite technique is a promising means for Tl(I) removal from wastewater. The catalytic hypochlorite oxidation induced by the magnetic biochar has also great potential to the effective removal of other pollutants.
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24688. 题目: Pyrolysis characteristics of soil humic substances using TG-FTIR-MS combined with kinetic models
文章编号: N19090603
期刊: Science of The Total Environment
作者: Tingting Li, Fanhao Song, Jin Zhang, Shasha Liu, Baoshan Xing, Yingchen Bai
更新时间: 2019-09-06
摘要: The incorporation and cycling of pyrogenic organic matter in soil is a potential carbon sink, while the pyrolysis behaviors of soil organic matter are still lacking. Pyrolysis characteristics of soil fulvic acid (FA) and humic acid (HA) were investigated using thermogravimetry combined with Fourier transform infrared spectrometer-mass spectrometer (TG-FTIR-MS) and kinetic models. Four reaction stages corresponding to four pseudo-components were distinguished for both FA and HA. FA exhibited greater transformation contributions of hemicellulose-like and cellulose-like pseudo-components, while HA exhibited greater transformation contributions of lignin-like pseudo-components. Compared to HA, higher levels of heat-resistant aromatic compounds, phenolic groups, and carboxylic groups were recognized in FA. Values of both activation energy (Ea, 246.13–661.40 kJ·mol−1) and pre-exponential factor (lnA, 53.49–107.16 min−1) of FA were greater than corresponding Ea (241.74–466.70 kJ·mol−1) and lnA (51.99–74.36 min−1) values of HA determined by Flynn-Wall-Ozawa method and Distributed Activation Energy Model. The main pyrolysis reaction mechanisms of both FA and HA closely matched with the order-based model corresponding to 2nd and 3rd order random nucleation on an individual particle. The evolved gas species of H2, CH4, H2O, and CO2 were dominant for FA and HA pyrolysis. Generally, the total H2/CO2 and CH4/H2O releases were relatively larger for FA and HA pyrolysis, respectively. TG-FTIR-MS is shown to be an effective method to provide valuable and qualitative analysis of the gaseous volatile species evolved during HS pyrolysis. Findings from this systematic study of soil organic matter responding to pyrolysis will be critical for predicting the changes of soil systems or carbon cycle affected by future climate and fire regimes.
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24689. 题目: Projected trends of soil organic carbon stocks in Meghalaya state of Northeast Himalayas, India. Implications for a policy perspective
文章编号: N19090602
期刊: Science of The Total Environment
作者: Gaurav Mishra, Krishna Giri, Abhishek Jangir, Rosa Francaviglia
更新时间: 2019-09-06
摘要: Agricultural and forestry activities can affect soil organic carbon (SOC) levels and CO2 emissions from terrestrial ecosystems due to land use changes. In Northeast Himalayas, studies on the effects of forest conversion to temporary agricultural lands (jhum) on the loss of SOC and soil quality degradation have received the attention of policy makers and scientific research. Presently, local communities are now oriented towards the settled plantations systems with modern cash crops such as tea and rubber, that could act as potential SOC sinks. However, no information on SOC dynamics and simulation studies after land-use change from temporary agricultural lands (jhum) to settled cultivations and under climate change (CC) conditions are available for the Meghalaya state. Applying the RothC model, we focused on four different scenarios including the conversion from jhum to settled cultivation (rubber plantations and tea gardens), as well as continuous jhum cultivation and jhum to jhum with a period of secondary succession. Simulations under CC conditions indicated that SOC stocks significantly increased by 1.20 t C ha−1 yr−1 in tea gardens compared to rubber and jhum scenarios. Conversely, SOC stocks slightly decreased by 0.07 t C ha−1 yr−1 in rubber plantations, while the regrowth of a natural vegetation cover as secondary succession following the abandonment of the jhum fields, showed a lower SOC decrease (0.18 t C ha−1 yr−1) compared to the continuous jhum cultivation (0.24 t C ha−1 yr−1). Thus, for CC mitigation in a policy perspective, tea gardens could represent the best land use to store increasing amounts of SOC in the long-term perspective and optimize farmers' incomes, while in rubber plantations SOC storage is limited in time. Jhum cultivation can benefit in terms of productivity and profitability by extending the duration of the secondary succession period.
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24690. 题目: Autochthonous dissolved organic matter potentially fuels methane ebullition from experimental lakes
文章编号: N19090601
期刊: Water Research
作者: Yongqiang Zhou, Lei Zhou, Yunlin Zhang, Javier Garcia de Souza, David C. Podgorski, Robert G.M. Spencer, Erik Jeppesen, Thomas A. Davidson
更新时间: 2019-09-06
摘要: Shallow lakes are hotspots for carbon processing and important natural sources of methane (CH4) emission. Ebullitive CH4 flux may constitute the overwhelming majority of total CH4 flux, but the episodic nature of ebullition events makes determining both quantity and the controlling factors challenging. Here we used the world's longest running shallow-lake mesocosm facility, where the experimental treatments are low and high nutrients crossed with three temperatures, to investigate the quantity and drivers of CH4 ebullition. The mean CH4 ebullition flux in the high nutrient treatment (41.5 ± 52.3 mg CH4–C m−2 d−1) mesocosms was significantly larger than in the low nutrient treatment (3.6 ± 5.4 mg CH4–C m−2 d−1) mesocosms, varying with temperature scenarios. Over eight weeks from June to August covered here warming resulted in a weak, but insignificant enhancement of CH4 ebullition. We found significant positive relationships between ebullition and chlorophyll-a, dissolved organic carbon (DOC), biodegradable DOC, δ2H, δ18O and δ13C-DOC, autochthonous dissolved organic matter (DOM) fluorescent components, and a fraction of lipids, proteins, and lignins revealed using ultrahigh-resolution mass spectrometry, and a negative relationship between ebullitive CH4 flux and the percentage volume inhabited of macrophytes. A 24 h laboratory bio-incubation experiment performed at room temperature (20 ± 2 °C) in the dark further revealed a rapid depletion of algal-DOM concurrent with a massive increased CH4 production, whereas soil-derived DOM had a limited effect on CH4 production. We conclude that eutrophication likely induced the loss of macrophytes and increase in algal biomass, and the resultant accumulation algal derived bio-labile DOM potentially drives enhanced outgassing of ebullitive CH4 from the shallow-lake mesocosms.
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24691. 题目: Characterization of activated sludge flocs in membrane bioreactor: stable and unstable flocs
文章编号: N19090515
期刊: Environmental Science and Pollution Research
作者: Yifei Sang, Shengli Wang, Lianfa Song, Jingbo Guo, Lanhe Zhang, Haifeng Zhang
更新时间: 2019-09-05
摘要: In this study, the properties of unstable and stable flocs were investigated under the steady operation of a membrane bioreactor (MBR). The extracellular polymeric substances (EPS) composition, surface charge, and hydrophobicity of unstable and stable flocs were examined and compared. Interfacial interactions of the membrane with unstable flocs, unstable flocs themselves, and unstable and stable flocs were assessed using the extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) models. Cake layer resistance was found to contribute more than 80% of total resistance under steady operating conditions. Compared with stable flocs, unstable flocs possessed a higher level of EPS, more diverse protein, more negative charge, weaker hydrophobicity, and higher fouling potential. Thermodynamic analyses showed that unstable flocs had a higher adhesive strength (− 63.4 mJ/m2) with the membrane, lower self-cohesive strength (− 18.3 mJ/m2), and higher cohesive strength (− 54.3 mJ/m2) with stable flocs. Therefore, some unstable flocs remained on the membrane surface to form the cake layer due to their poor cohesion strength.
24692. 题目: Warm Events Induce Loss of Resilience in Organic Carbon Production in the Northeast Pacific Ocean
文章编号: N19090514
期刊: Global Biogeochemical Cycles
作者: Mariana B. Bif, Leo Siqueira, Dennis A. Hansell
更新时间: 2019-09-05
摘要: Between 2013 and 2016, a series of warm events induced by ocean‐atmosphere oscillations negatively impacted productivity in the northeast Pacific Ocean. For two consecutive winters (2013‐2014 and 2014‐2015), suppressed wind stress and warm near‐surface ocean temperature anomalies restricted vertical mixing between the surface and underlying nutrient‐enriched waters. Here we assess historical data of sea surface temperature and sea level pressure, along with nearly a decade of biogeochemical float data to evaluate the impact of these warm events on organic carbon production. The first stratified winter experienced little apparent impact on the magnitude of net organic carbon production in the growing season relative to prior years, suggesting an immediate resilience from reduced new nutrients, apparently depending on recycled iron. However, the subsequent winter experienced virtually zero net production; a loss of resilience, perhaps due to net iron removal with export, was evident. We find that consistently enhanced winter stratification decreased carbon production much more so than a single warm winter. This study highlights the sensitivity of marine productivity to ocean‐atmosphere oscillations, reducing deep ocean carbon sequestration with prolonged ocean warming and stratification.
24693. 题目: Influence of biogenic organics on the chemical composition of Arctic aerosols
文章编号: N19090513
期刊: Global Biogeochemical Cycles
作者: J.H. Choi, E. Jang, Y.J. Yoon, J.Y. Park, T.‐W. Kim, S. Becagli, L. Caiazzo, D. Cappelletti, R. Krejci, K. Eleftheriadis, K.‐T. Park, K.S. Jang
更新时间: 2019-09-05
摘要: We use an ultrahigh‐resolution 15 Tesla Fourier transform ion cyclotron resonance mass spectrometer (15T FT‐ICR MS) to elucidate the compositional changes in Arctic organic aerosols collected at Ny‐Ålesund, Svalbard, in May 2015. The FT‐ICR MS analysis of airborne organic matter provided information on the molecular compositions of aerosol particles collected during the Arctic spring period. The air mass transport history, combined with satellite‐derived geographical information and chlorophyll concentration data, revealed that the molecular compositions of organic aerosols drastically differed depending on the origin of the potential source region. The protein and lignin compound populations contributed more than 70% of the total intensity of assigned molecules when the air masses mainly passed over the ocean region. Interestingly, the intensity of microbe‐derived organics (protein and carbohydrate compounds) was positively correlated with the air mass exposure to phytoplankton biomass proxied as chlorophyll. Furthermore, the intensities of lignin and unsaturated hydrocarbon compounds, typically derived from terrestrial vegetation, increased with an increase in the advection time of the air mass over the ocean domain. These results suggest that the accumulation of dissolved biogenic organics in the Arctic Ocean possibly derived from both phytoplankton and terrestrial vegetation could significantly influence the chemical properties of Arctic organic aerosols during a productive spring period. The interpretation of molecular changes in organic aerosols using an ultrahigh‐resolution mass spectrometer could provide deep insight for understanding organic aerosols in the atmosphere over the Arctic and the relationship of organic aerosols with biogeochemical processes in terms of aerosol formation and environmental changes.
24694. 题目: Hydrologic shifts create complex transient distributions of particulate organic carbon and biogeochemical responses in beach aquifers
文章编号: N19090512
期刊: Journal of Geophysical Research: Biogeosciences
作者: Kyra H. Kim, Holly A. Michael, Erin K. Field, William J. Ullman
更新时间: 2019-09-05
摘要: Biogeochemical reactions within intertidal zones of coastal aquifers have been shown to alter the concentrations of terrestrial solutes prior to discharge to surface waters. In organic‐poor sandy aquifers, the input of marine organic matter from infiltrating seawater supports active biogeochemical reactions within the sediments. However, while the seasonality of surface water organic carbon concentrations (primary production) and groundwater mixing have been documented, there is limited understanding of the transience of various organic carbon pools (porewater particulate, dissolved, sedimentary) within the aquifer and how these relate to the location and magnitudes of biogeochemical reactions over time. To understand the relationship between changes in groundwater flow and the seasonal migration of geochemical patterns, beach porewater and sediment samples were collected and analyzed from six field sampling events spanning two years. While the seasonally‐dynamic patterns of aerobic respiration closely followed those of salinity, redox conditions and nutrient characteristics (distributions of N and P, denitrification rates) were unrelated to contemporaneous salinity patterns. This divergence was attributed to the spatial variations of reactive particulate organic carbon distributions, unrelated to salinity patterns, likely due to filtration, retardation, and immobilization dynamics during transport within the sediments. Results support a “carbon memory” effect within the beach, with the evolution and migration of reaction patterns relating to the distribution of these scattered carbon pools as more mobile solutes move over less mobile pools during changes in hydrologic conditions. This holds important implications for the prediction and quantification of biogeochemical reactions within beach systems.
24695. 题目: Response of organic carbon fractions and microbial community composition of soil aggregates to long-term fertilizations in an intensive greenhouse system
文章编号: N19090511
期刊: Journal of Soils and Sediments
作者: Lihong Tong, Ling Zhu, Yizhong Lv, Kun Zhu, Xiayan Liu, Rui Zhao
更新时间: 2019-09-05
摘要: Purpose: Soil organic carbon (SOC) content and stability, which are regulated by microbial communities, vary depending on aggregate size. The objectives of this study were to investigate the distribution of the SOC fraction and microbial community composition within soil aggregates when subjected to different fertilization treatments. Materials and methods: This study used high-throughput sequencing technology to analyze the soil microbial community distribution in different-sized aggregate fractions [> 2 mm (large macro-aggregates), 2–0.25 mm (small macro-aggregates), and < 0.25 mm (microaggregates)] when they were subjected to different fertilization treatments in a 16-year greenhouse experiment. The three treatments were chemical fertilizer (CF), 50% organic fertilizer + 50% chemical fertilizer (MF), and organic fertilizer (OF). Results and discussion: The results showed that the application of organic fertilizer significantly increased the soil organic carbon (SOC), dissolvable organic carbon (DOC), and microbial biomass carbon (MBC) contents and changed microbial community composition in all the different-sized soil aggregates. We observed that OF significantly reduced the relative abundance of bacterial communities in all aggregates and significantly increased the relative abundances of fungal communities in small macro-aggregates. The larger fungal communities in small macro-aggregates could promote soil aggregation and C sequestration. Conclusions: Organic fertilization increased the substrate contents in soil aggregates and enhanced soil aggregation and microbial activity in macro-aggregates, which are critical factors that facilitate C transformation and sequestration. These improvements resulted in significantly improved soil fertility and increased vegetable yield in the greenhouses.
24696. 题目: Evaluation of caffeine adsorption by MgAl-LDH/biochar composite
文章编号: N19090510
期刊: Environmental Science and Pollution Research
作者: Pollyanna Vanessa dos Santos Lins, Danielly Carlos Henrique, Alessandra Honjo Ide, Carmem Lúcia de Paiva e Silva Zanta, Lucas Meili
更新时间: 2019-09-05
摘要: In the present work, the composite MgAl-LDH/biochar using activated carbon from bovine bone as support for the layered double hydroxide particles was successfully synthesised and used as an alternative adsorbent for caffeine removal from water. Kinetic studies showed that the equilibrium was achieved in only 20 min of contact between the adsorbent and the adsorbate. The pseudo-first-order model represented the experimental data more satisfactorily (R2 = 0.95), suggesting a physical adsorption process. The isotherms were performed at three temperatures, in which it was observed the decrease in the adsorption in higher temperatures. It was obtained a maximum adsorption capacity of 26.219 mg/g at 40 °C, and the experimental data were better adjusted by Redlich–Peterson, R2 > 0.9942. In short, the study demonstrated that the composite was satisfactorily synthesised and its use in the caffeine removal was quite attractive, being a potential adsorbent for water treatment applications.
24697. 题目: Variations in the rate of accumulation and chemical structure of soil organic matter in a coastal peatland in Sarawak, Malaysia
文章编号: N19090509
期刊: CATENA
作者: Faustina E. Sangok, Yuki Sugiura, Nagamitsu Maie, Lulie Melling, Toshio Nakamura, Kosuke Ikeya, Akira Watanabe
更新时间: 2019-09-05
摘要: To determine the variation in the rate of accumulation and chemical structure of soil organic matter (SOM) in a tropical coastal peatland, series of soil cores samples were collected in the Maludam National Park, Sarawak, Malaysia and analyzed. Duplicate soil core samples were collected from three phasic communities in the peat swamp forests, Mixed Peat Swamp (MPS; depth of 50–450 cm), Alan Batu (ABt; depth of 200–700 cm), and Alan Bunga (ABg; depth of 200–800 cm), which were located at outer, middle, and inner sites on the peat dome. The 14C age of the SOM was determined at depths of every 50 or 100 cm and 4–6 samples from each profile were subjected to ramp cross polarization/magic angle spinning 13C nuclear magnetic resonance (NMR) analysis. The 14C age of SOM ranged from 1602 to 5162 years before the present (yBP), 1134–4043 yBP, and 928–3376 yBP in the cases of the MPS, ABt, and ABg forests, respectively. Those after calibration were in the ranges of 1482–5958 (MPS), 1322–4603 (ABt), and 837–3629 (ABg) yBP. The relationship between calibrated 14C age and soil depth, when regressed to a linear function with the constraint that the age of surface sediment is 0 year, showed that the rate of peat accumulation was 0.60 ± 0.01 (MPS), 1.5 ± 0.0 (ABt), and 1.9 ± 0.1 (ABg) mm y−1. However, in the case of the MPS forest, this rate was not constant but decreased toward the present. The 13C NMR results showed the decrease in the relative abundance of alkyl C and an increase in that of carbohydrate C with soil age/depth in the MPS forest soil profiles, suggesting an acceleration in the decomposition of SOM as the cause of the decrease in the rate of accumulation of the peat. Variations in the C composition of the other two forest soils with soil age were small. The relative content of aromatic C remained relatively constant, indicating that aromatic C is consistently a major component of the C pool throughout the peat soil layers.
24698. 题目: Comprehensive study on the formation of brominated byproducts during heat-activated persulfate degradation
文章编号: N19090508
期刊: Chemical Engineering Journal
作者: Ziying Wang, Yisheng Shao, Naiyun Gao, Bin Xu, Na An, Xian Lu
更新时间: 2019-09-05
摘要: Applying the highly oxidative sulfate radical (SO4) to pollutant degradation may cause it to react with the coexisting bromide (Br−) to form undesired byproducts. This study investigated the transformation of Br− during the degradation process of a contaminant (diethyl phthalate (DEP)) via heat-activated persulfate (PS). Dibromoacetonitrile and bromoform formed with Br− and natural organic matter (NOM) in the solution, while only bromoform was detected without NOM. The formation of these brominated disinfection byproducts (Br-DBPs) can be ascribed to the reactions between the phenolic groups of DEP degradation intermediates or NOM and reactive bromine species (free bromine and radical bromine) generated through the oxidation of Br− by SO4. Br-DBPs were degraded by excessive SO4, which indicates that organic bromine is a temporary phase during the turnover of Br−. The time-dependent formation of organic and inorganic bromines suggests that Br− may have cycled several times between organic and inorganic forms before eventually turning into bromate. The bromate formation showed a lag phase before continuously increasing. Generally, increasing the temperature, PS dosage, and Br− and organic matter (DEP and NOM) concentrations increased the maximum concentration of Br-DBPs. Additionally, these reaction parameters facilitated bromate formation except for organic matter, whose inhibitory effect is probably due to the consumption of reactive species by organic matter and the generated superoxide anion. The total organic carbon concentration of the solution exhibited a relatively quick reduction followed by a slow decrease. These results highlight the potential risks of PS activation technologies and can help prevent such risks in actual practice.
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24699. 题目: Effect of swine biogas slurry application on soil dissolved organic matter (DOM) content and fluorescence characteristics
文章编号: N19090507
期刊: Ecotoxicology and Environmental Safety
作者: Lilong Yan, Qingping Liu, Cong Liu, Yue Liu, Mingyue Zhang, Yudan Zhang, Ying Zhang, Wanrong Gu
更新时间: 2019-09-05
摘要: The application of biogas slurry as an organic fertilizer is a promising method for utilizing breeding manure wastewater. At present, the impact of biogas slurry on the properties of organic matter in soil is not clear. In this study, a pot experiment in which chemical fertilizers were replaced with biogas slurry from a swine farm was performed. The fluorescence spectra combined with parallel factor (PARAFAC) analysis and principal component analysis (PCA) were used to explore the influence of biogas slurry on the protein and humic substance contents in the dissolved organic matter (DOM) in soil. The results showed that there were two proteins (component 3 (C3) and component 4 (C4)) and two humic substances ( component 1 (C1) and component 2 (C2)) in the DOM of the experimental soil. The application of swine biogas slurry can significantly increase the content of DOM in soil, but the increase was weakened with extended time. Compared with the CKA, the biogas slurry significantly increased the C1, C2, C3 and C4 contents in the initial stage by 116.17%, 76.41%, 578.71% and 278.13%, respectively. Within 28 days of planting corn, proteins with simple molecular structure in the DOM in the soil began to be transformed into humic substances with high molecular weight and more complex molecular structures. On the 60th day, the contents of C1 and C2 in the DOM of the treated treatments soil increased by 13.72%–34.40% and 5.05%–17.78% respectively, and tyrosine content decreased by 90.11%–94.41%. This study provides a new perspective on the effects of biogas slurry application on soil properties and sustainable utilization of soil.
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24700. 题目: The main factors controlling spatial variability of soil organic carbon in a small karst watershed, Guizhou Province, China
文章编号: N19090506
期刊: Geoderma
作者: Yunxing Bai, Yunchao Zhou
更新时间: 2019-09-05
摘要: Soil organic carbon (SOC) is an important component of the global carbon pool. Assessment of SOC in a karst mountainous area is a great challenge due to the high spatial heterogeneity in topography, land use and soil. This study used 2755 soil samples from a karst watershed in southwestern China to quantitatively study the spatial variability in SOC in this small karst watershed. The effects of parent soil material, soil type, land use, slope position, slope orientation and rock exposure rate on the spatial distributions of SOC in the karst watershed were compared by statistical modelling. The results showed that the SOC content in the study area was 25.01 g/kg, and the coefficient of variation was 55.26%, indicating moderate-intensity variation. The nugget coefficient C0/(C0 + C) was >0.70, and the spatial distribution of SOC was mainly affected by structural factors. Parent soil material, soil type, land use, slope position, slope direction and rock exposure rate had significant effects on the SOC (p < 0.001). The independent interpretation of SOC spatial variation by influencing factors is as follows: soil family level (37.40%) > land use (23.10%) > rock exposure rate (22.10%) > soil group level (17.50%) > parent material (10.90%) > slope position (7.20%) > slope direction (5.10%). Soils in the lower soil categories of the soil classification system were better able to reflect SOC spatial distributions. When soil family levels, land uses and rock exposure rates are used as predictors, 56.60% of SOC variability can be explained. Therefore, it is advisable to use a combination of soil family levels, land uses and rock exposure rates as the main controlling factor for predicting or assessing SOC spatial distributions in karst areas.
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