13961. 题目: Diagenetic mobilization of Ti and formation of brookite/anatase in early Cambrian black shales, South China
期刊: Chemical Geology
作者: Ze-Rui Ray Liu, Mei-Fu Zhou, Anthony E. Williams-Jones, Wei Wang, Jian-Feng Gao
摘要: Titanium (Ti) is typically hosted in detrital minerals in marine sediments and has long been considered to be immobile during diagenesis. In this study, the authigenic titania minerals, brookite and anatase, are observed in early Cambrian carbonaceous shales from the Meishucun and Zhajin sections of South China, respectively. Black shales in the Meishucun section have total organic carbon (TOC) contents from 1.6 to 3.9 wt% and HI (hydrogen index) values from 3.8 to 20 mg HC/g TOC, whereas black shales in the Zhajin section have much higher TOC (7.1–15.6 wt%) but lower HI (<2.0 mg HC/g TOC) and contain abundant bitumen (~3 vol%). Brookite in black shales from the Meishucun section crystallized invariably along cleavages of detrital biotite. This intimate association suggests that the Ti required to form titania minerals was derived from detrital biotite and that Ti was mobilized only on a nano- to micro-meter scale. In contrast, anatase aggregates in black shales from the Zhajin section are intergrown with bitumen. It is proposed that Ti in these shales was mobilized in low pH organic-rich fluids and, subsequently, preferentially precipitated as anatase with increasing pH. The mobilization of inert Ti in black shales is indicative of a possible diagenetic or post-diagenetic elemental redistribution in carbonaceous rocks. Our study further demonstrates that proxies based on geochemical component of black shales can be employed to estimate redox state of ancient oceans, but must be applied with caution.
13962. 题目: Soil Organic Carbon and Isotope Composition Response to Topography and Erosion in Iowa
期刊: Journal of Geophysical Research: Biogeosciences
作者: Xia Li, Gregory W. McCarty, Douglas L. Karlen, Cynthia A. Cambardella, William Effland
摘要: Soil redistribution (erosion and deposition) can greatly affect the fate of soil organic carbon (SOC) in agroecosystems. Landscape topography is one of the key factors controlling erosion processes and creating spatial variability in SOC. We combined carbon (C) isoscape (isotopic landscape) analysis, historic orthophoto interpretation, cesium (137Cs) inventory measurement, and digital terrain analysis to quantify SOC dynamics and soil redistribution relationship and their responses to landscape topography in an Iowa cropland field with soybean/maize (C3/C4) rotation. The historic orthophotos and 137Cs were used to reflect soil redistribution before and after the 1960s, respectively. Topography‐based models were developed to simulate 137Cs inventory, SOC density, and C isotopes using stepwise principal component regression. Spatial patterns of SOC were similar to soil erosion/deposition patterns with high SOC density in depositional areas and low SOC density in eroded areas. Soil redistribution, SOC density, and isotopic signature of SOC (δ13C) were highly correlated with topographic metrics, suggesting that topographic heterogeneity drove the spatial variability in erosion and SOC dynamics. Considering the isotopic composition of SOC, C3‐derived SOC density was strongly controlled by topographic metrics, but C4‐derived SOC density showed weaker expression of spatial pattern and poor correlation to topographic parameters. The resulting topography‐based stepwise principal component regression models captured more than 60% of the variability in SOC density, δ13C, and C3‐derived SOC density but could not reliably predict C4‐derived SOC density. Our results indicate that exploring C isotopes in response to soil erosion is important to understand the fate of eroded SOC within croplands under C3/C4 cultivation.
13963. 题目: Changes in soil properties and soil organic carbon stocks along an elevation gradient at Mount Bambouto, Central Africa
作者: Désiré Tsozué, Jean Pierre Nghonda, Paul Tematio, Simon Djakba Basga
摘要: The study was designed to investigate the influence of elevation gradient on soil properties and soil organic carbon (SOC) in the Bambouto Mountain in Western Cameroon and the subsequent consequences of human activities on these SOC contents. Five sites, Bawa, Zavion, Totap, Camp Bororo and Meletan, were selected between 1400 m and 2740 m altitude to conduct the study. Three sampling points per site were allocated and each selected point was sampled using depth increments of 25 cm from the soil surface. The studied soils are characterized by low gravel contents. SOC contents and stock (SOCS) decrease with depth at all sites and increase along the elevation gradient, reaching the highest content (123.67 ± 30.44 g kg−1) at 2100 m a.s.l. Higher SOCS (157.14 ± 23.75 Mg ha−1) were found in 0–25 cm depth at Meletan at 2740 m a.s.l. while the lowest SOCS (86.04 ± 3.19 Mg ha−1) in the same depth was found in Bawa at 1500 m a.s.l. It increased and was significantly correlated with elevation (r = 0.86; p < 0.05), reaching a total of 302.15 ± 34.55 Mg ha−1 at 2740 m a.s.l. The difference might be attributed to longer vegetative growing periods at the high altitude without human interference in comparison with the lower altitude. Amorphous Fe and Al exhibited weak correlations with total SOCS along the altitudinal gradient, implying that their role on the stabilization of SOC might be little. The accumulation and stabilization of SOC is ascribed to clay content, parent material, climate and vegetation, which are controlled by the elevation gradient.
13964. 题目: Systematic chemotaxonomic profiling and novel paleotemperature indices based on alkenones and alkenoates: potential for disentangling mixed species input
期刊: Organic Geochemistry
作者: Yinsui Zheng, Patrick Heng, Maureen H. Conte, Richard S. Vachula, Yongsong Huang
摘要: The unsaturation indices (U37K, U37) of long chain alkenones are powerful paleotemperature proxies and have been widely applied for sea surface temperature (SST) reconstructions in the past three decades. However, these indices encounter major difficulties in systems harboring different alkenone-producing haptophyte species, such as saline lakes and marginal ocean environments. All haptophytes produce C37 alkenones, but different species often display large differences in temperature calibrations and may bloom in different seasons, hindering the use of U37K, U37 indices for reliable paleotemperature reconstructions in mixed systems. To overcome these problems, we have recently reported a new analytical method that allows comprehensive separation of up to 32 alkenones, alkenoates and their double bond positional isomers in culture and sediment samples. Here we report a systematic analysis of alkenones and alkenoates from six haptophyte cultures growing at a wide range of temperatures (4–25 °C). Together with a compilation of 230 previously published culture data sets, we present here systematic calibrations of temperature-sensitive indices based on all alkenone and alkenoate homologues (including isomers). Using this dataset, we extract systematic chemotaxonomic criteria for differentiating individual haptophyte species and demonstrate such chemotaxonomic features can be encoded into a machine learning model for reliable species identifications. Specifically, we show that temperature calibrations based on C38 methyl ketones and C39 ethyl ketones are potentially useful for disentangling mixed inputs in estuarine systems where Group III (E. huxleyi) and Group II alkenones mix, and that C36 ethyl alkenoate isomeric ratios display minimal species heterogeneity and are potentially more suited for reconstructing temperatures in mixed systems with different Group II haptophytes. Using the culture data as base profiles, we construct a mathematical model for estimating percentage inputs from alkenones of different Isochrysidales groups in mixed systems, with potential implications for inferring past salinity changes. Overall, the results from this study demonstrate important new applications of alkenone and alkenoate biomarkers in paleoclimate and paleoenvironmental research.
13965. 题目: Effective treatment of reverse osmosis concentrate from incineration leachate using direct contact membrane distillation coupled with a NaOH/PAM pre-treatment process
作者: Jinyu Shi, Yan Dang, Dan Qu, Dezhi Sun
摘要: Reverse osmosis is frequently used to process biologically treated leachate from municipal solid waste incineration plants. Reverse osmosis concentrate from incineration leachate (ROCIL) contains extremely high concentrations of monovalent and divalent ions (e.g. Na+, K+, Mg2+, and Ca2+) and some refractory organic pollutants (e.g. humic substances). In this study, lab-scale direct contact membrane distillation (DCMD) coupled with pre-treatment was applied to treat ROCIL. NaOH and polyacrylamide (PAM) chemical precipitation and coagulation pretreatment effectively removed Ca2+ and Mg2+ (>99%) from the ROCIL, which also significantly improved the treatment efficiency of DCMD and slowed down membrane fouling caused by Mg5(CO3)4(OH)2·4H2O and CaCO3 scaling on the membrane surface. During the long-term operation of DCMD, ROCIL was concentrated 21 times and nearly all of the inorganic ions (>99.9%) and organic matter (>99%) were removed from the pre-treated ROCIL. A strong interaction occurred due to the accumulation of humic substances and metal ions in the feed solution, which lead to inorganic and organic scaling deposited on the membrane surface and pores, but the wetting phenomenon was not serious. These results demonstrated that DCMD coupled with NaOH/PAM pre-treatment can be a potential alternative for further treatment and concentration of ROCIL to obtain high quality water.
13966. 题目: Potassium lignosulfonate as a washing agent for remediating lead and copper co-contaminated soils
期刊: Science of The Total Environment
作者: Qianjun Liu, Yu Deng, Jiepeng Tang, Di Chen, Xiang Li, Qintie Lin, Guangcai Yin, Min Zhang, Huawen Hu
摘要: Lignin is a renewable aromatic polymer which is present in large quantities in the cell walls of terrestrial plants and is the main binding agent for fibrous plant components. Potassium lignosulfonate (KLS), as a by-product of pulping processes, can be applied to agricultural fields as a soil conditioner and chelate fertilizer. In this study, based on its solubility and complexing ability, batch washing and column leaching was explored to evaluate the potential application of KLS in the washing remediation of soil contaminated with lead and copper. Under optimum conditions KLS concentration of 8%, pH of 5.24 and 6 h duration, the removal ratios for the simulated and mining area soils in the batch experiment were 67.40% and 52.87% respectively, for Pb and 73.42% and 55.20% respectively, for Cu. In the column leaching experiment, the removal efficiencies of Pb and Cu increased with solution volume and that the removal ratios of the simulated and mining area soils were 36.46% and 20.31%, respectively, for Pb and 39.74% and 22.76%, respectively, for Cu. KLS can reduce the ratio of acid-soluble and reducible fractions, which may have the most potential hazardous and poisonous for plants. Cation exchange capacity (CEC) and pH of soil were all stable after washing. However, the organic matter and available K, N, and P in the treated soil, which are important factors for plant growth increased significantly. This study showed that KLS can remove Pb and Cu from soil, while improve nutrient (ammonium nitrogen, available phosphorus and available potassium) levels of soil.
13967. 题目: Assessing paleohydrologic controls on the hydrogen isotope compositions of leaf wax n-alkanes in Chinese peat deposits
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Xianyu Huang, Philip A. Meyers
摘要: The high concentrations of lipid biomarkers in peat and the close relation between peatland development and hydrological conditions merit further assessment of the paleohydrological proxy potential of the 2H/1H ratio of leaf wax n-alkanes (δ2Halk) in peat deposits. In the context of the dynamics of the East Asian summer monsoon, detailed investigation of modern processes is an important way to improve our understanding of the controls on δ2Halk records from Chinese peat deposits. This review first synthesizes the results of investigations of modern processes in the Dajiuhu peatland of central China, complemented by results from other peatlands and nearby non-peatland sites, to evaluate how the 2H/1H ratio changes from source water to leaf water and then to lipids in leaf waxes and ultimately to peat deposits. The results reveal that the precipitation δ2H values and the peatland plant types are the two major factors that control the δ2Halk signals preserved in peat at Dajiuhu. Comparison of results from Holocene δ2Halk sequences from other Chinese peat deposits illustrates how peat δ2Halk values respond to paleoclimate changes on centennial to millennial timescales throughout the East Asian summer monsoon region. Finally, proposed incubations of peat-forming plants in controlled chambers that could assess the response of plant δ2Halk values to environmental stresses are described. As an example, responses of the compound-specific biomarker δ2H and δ13C values of Sphagnum, the dominant plant in the Dajiuhu peatland, could provide important information on the symbiotic relation between Sphagnum and microbes. It is expected that experiments such as these that combine the carbon and hydrogen isotope compositions of multiple lipids will yield important new insights into the responses of peatland ecosystems to climate changes.
13968. 题目: Effect of biochar on the physical and structural properties of a desert sandy soil
作者: Giorgio Baiamonte, Giuseppina Crescimanno, Francesco Parrino, Claudio De Pasquale
摘要: Biochar application to soil can be considered as a means to improve soil quality, thereby optimizing irrigation management and reducing irrigation needs, especially in dryland regions. This paper is aimed at investigating the effect of biochar (BC) on a desert sandy soil (Al Foah, United Arab Emirates) in terms of bulk density, porosity, water retention, plant available water (AWmax), aggregate stability (AS) and specific surface area (BET-SSA). BC was produced from forest biomass (Italy). Soil water retention was measured by the High Energy Moisture Characteristic (HEMC) and by pressure plate measurements, by using BC fractions equal to 0 (soil only), 0.014, 0.091, 0.23, 0.33 and 1 (BC only). The results indicated that BC significantly (p = 0.05) increased soil porosity and the amount of storage pores. As a consequence, water retention was enhanced and AWmax from 19.3 mm/m for the sandy soil (fbc = 0), to 60.8, 102.3 and 107.6 at fbc = 0.091, 0.23, and 0.33, respectively, was raised. No significant effects of BC were detected on the soil water retention curve of the BC-amended soil at fbc = 0.014, compared to the original condition. The significant increase in the structural index (SI) at fbc, ≥0.091, indicated that BC improved soil aggregate stability. The BET-SSA was measured by nitrogen adsorption measurements and indicated that the connected porosity was significantly increased by the 0.091 BC fraction. Both AWmax and SI were found to be correlated with BET-SSA. This showed an outcome that has been so far little investigated, namely that the BET-SSA played a significant role in the mechanism affecting the soil response to BC addition. The results showed that application of BC can improve soil structure and water retention and therefore optimize irrigation management by reducing irrigation needs, in the Al-Foah area and/or in similar dryland regions.
13969. 题目: Variability of the Pacific-derived Arctic water over the southeastern Wandel Sea shelf (Northeast Greenland) in 2015-2016
期刊: Journal of Geophysical Research: Oceans
作者: Igor A. Dmitrenko, Sergei A. Kirillov, Bert Rudels, David G. Babb, Paul G. Myers, Colin A. Stedmon, Jørgen Bendtsen, Jens K. Ehn, Leif Toudal Pedersen, Søren Rysgaard, David G. Barber
摘要: A portion of the freshwater transport through Fram Strait consists of low salinity Pacific‐derived Arctic water flowing southward along the east coast of Greenland. The pathways of this water are currently unclear. An Ice Tethered Profiler deployed over the southeastern Wandel Sea shelf (Northeast Greenland) in May 2015 collected a profile every 3 hours for a year recording salinity‐temperature‐depth (CTD) and Colored Dissolved Organic Matter (CDOM) fluorescence. This was accompanied by velocity observations. The CTD data revealed that the sub‐surface water (~15‐85 m depth) characterised by high CDOM resembles the “cold Halostad” in the Canada Basin formed by the injection of Pacific water. A coastal branch of the Pacific water outflow from the Arctic Ocean supplies the Wandel Sea halostad, which shows a clear seasonal pattern. From July to October‐November, the halostad is shallow, more saline, warmer, and with less CDOM. Conversely, from November to April, the halostad deepens, cools, freshens and CDOM increases, likely indicating a higher fraction of Pacific winter water. The CTD surveys, wind and current data, and numerical simulations show that the seasonal variation of wind over the continental slope likely controls seasonal changes of this intermediate water layer. Over northeast Greenland, winter winds have a northerly component from November to April, favouring Ekman transport of the Pacific‐derived water to the Wandel Sea shelf. In contrast, the prevailing southerly summer winds result in retreat of the Pacific‐derived water off the shelf. The landfast ice off‐slope extension modifies wind‐forcing disrupting seasonal patterns.
13970. 题目: Impact of land use on the DOM composition in different seasons in a subtropical river flowing through a region undergoing rapid urbanization
期刊: Journal of Cleaner Production
作者: Qi Liu, Yuan Jiang, Yulu Tian, Zhaojiang Hou, Kejian He, Lan Fu, Hui Xu
摘要: The dissolved organic matter (DOM) composition in river ecosystems can reflect human impacts on the river ecosystem, and plays an important role in the carbon cycling process. We collected water and phytoplankton samples at 107 sites in the Dongjiang River in two seasons to assess the impact of the sub-catchments land use composition. The results showed that (1) the forested sub-catchments had higher humic-like C1 (16.45%) and C2 (25.04%) and lower protein-like C3 (22.57%) and C4 (35.95%) than the urbanized and mixed forest-agriculture sub-catchments, while the urbanized sub-catchments showed an inverse trend (4.54%, 15.51%, 33.97% and 45.98%, respectively). (2) A significant variation in the proportion of C1 and C4 between the dry and rainy seasons was recorded in both the forested and the mixed forest-agriculture sub-catchments (p < 0.01), but only C4 showed an obvious seasonal variation in the urbanized sub-catchments (p < 0.01); while the DOM composition was mainly related to the proportion of urbanized and forested land year-round (p < 0.01). (3) No significant correlation was found in either season between the DOM composition and the agricultural land proportion (p > 0.05). Our findings indicated that the DOM composition was strongly dependent on the land use composition of the sub-catchments and varied seasonally, but the seasonal variation pattern could be disturbed by human activities in the extensively urbanized catchments. Notably, when considering bioavailability, the higher C4 proportion compared with those in temperate rivers implied a larger amount of CO2 released from subtropical rivers into the atmosphere.
13971. 题目: A systematic investigation on the bactericidal transient species generated by photo-sensitization of natural organic matter (NOM) during solar and photo-Fenton disinfection of surface waters
期刊: Applied Catalysis B: Environmental
作者: Mona Kohantorabi, Stefanos Giannakis, Mohammad Reza Gholami, Ling Feng, Cesar Pulgarin
摘要: In this work, the role of dissolved oxygen in the solar and the photo-Fenton-mediated E. coli inactivation process was put under scrutiny. The effect of transient species that were produced in the presence of various natural organic matter isolates (NOM), namely Suwannee River (SR) NOM, Nordic Reservoir (NR) NOM, SR Humic acid (SRHA), and SR Fulvic acid (SRFA) was studied in detail. The role of 1O2 in this reaction was systematically evaluated by modifying the O2 concentration (N2/O2 purging) and the matrix composition (10, 50, and 100% deuterium oxide (D2O) v/v). In the presence of NOM, 1O2 was generated and the enhancement of E. coli inactivation rate due to charge transfer from triplet state to molecular oxygen. The comparison between SR and NR NOM showed that for these compounds, triplet state of NOM (3NOM*), and 1O2 were the more favorable active species in E. coli inactivation, respectively. Also, the second order rate constants (k2ndE.coli) of E. coli with 3NOM*, and 1O2 were calculated by using the steady state approximation. The obtained results showed that the rate values of 1O2 related to NR NOM was ∼ 5.6 times higher than SR NOM, while the rate values of 3NOM* for SR NOM was ∼ 8.7 times higher than NR NOM. We also determined the effect of these organic matter isolates in the photo-Fenton process and its constituents (solar/Fe2+, solar/H2O2, and solar/Fe2+/H2O2). In presence of NOM, the photo-Fenton process inactivation rates increased which confirmed that the combined processes has additional pathways generated with disinfecting effect during solar exposure of bacteria.
13972. 题目: Microbial Mercury Methylation in Aquatic Environments: A Critical Review of Published Field and Laboratory Studies
期刊: Environmental Science & Technology
作者: Olof Regnell, Carl. J. Watras
摘要: Methylmercury (MeHg) is an environmental contaminant of concern because it biomagnifies in aquatic food webs and poses a health hazard to aquatic biota, piscivorous wildlife and humans. The dominant source of MeHg to freshwater systems is the methylation of inorganic Hg (IHg) by anaerobic microorganisms; and it is widely agreed that in situ rates of Hg methylation depend on two general factors: the activity of Hg methylators and their uptake of IHg. A large body of research has focused on the biogeochemical processes that regulate these two factors in nature; and studies conducted within the past ten years have made substantial progress in identifying the genetic basis for intracellular methylation and defining the processes that govern the cellular uptake of IHg. Current evidence indicates that all Hg methylating anaerobes possess the gene pair hgcAB that encodes proteins essential for Hg methylation. These genes are found in a large variety of anaerobes, including iron reducers and methanogens; but sulfate reduction is the metabolic process most often reported to show strong links to MeHg production. The uptake of Hg substrate prior to methylation may occur by passive or active transport, or by a combination of both. Competitive inhibition of Hg uptake by Zn speaks in favor of active transport and suggests that essential metal transporters are involved. Shortly after its formation, MeHg is typically released from cells, but the efflux mechanisms are unknown. Although methylation facilitates Hg depuration from the cell, evidence suggests that the hgcAB genes are not induced or favored by Hg contamination. Instead, high MeHg production can be linked to high Hg bioavailability as a result of the formation of Hg(SH)2, HgS nanoparticles, and Hg–thiol complexes. It is also possible that sulfidic conditions require strong essential metal uptake systems that inadvertently bring Hg into the cytoplasm of Hg methylating microbes. In comparison with freshwaters, Hg methylation in open ocean waters appears less restricted to anoxic environments. It does seem to occur mainly in oxygen deficient zones (ODZs), and possibly within anaerobic microzones of settling organic matter, but MeHg (CH3Hg+) and Me2Hg ((CH3)2Hg) have been shown to form also in surface water samples from the euphotic zone. Future studies may disclose whether several different pathways lead to Hg methylation in marine waters and explain why Me2Hg is a significant Hg species in oceans but seemingly not in most freshwaters.
13973. 题目: Correlative Imaging Reveals Holistic View of Soil Microenvironments
期刊: Environmental Science & Technology
作者: Steffen Schlüter, Thilo Eickhorst, Carsten W. Mueller
摘要: The microenvironmental conditions in soil exert a major control on many ecosystem functions of soil. Their investigation in intact soil samples is impaired by methodological challenges in the joint investigation of structural heterogeneity that defines pathways for matter fluxes and biogeochemical heterogeneity that governs reaction patterns and microhabitats. Here we demonstrate how these challenges can be overcome with a novel protocol for correlative imaging based on image registration to combine three-dimensional microstructure analysis of X-ray tomography data with biogeochemical microscopic data of various modalities and scales (light microscopy, fluorescence microscopy, electron microscopy, secondary ion mass spectrometry). Correlative imaging of a microcosm study shows that the majority (75%) of bacteria are located in mesopores (<10 μm). Furthermore, they have a preference to forage near macropore surfaces and near fresh particulate organic matter. Ignoring the structural complexity coming from the third dimension is justified for metrics based on size and distances but leads to a substantial bias for metrics based on continuity. This versatile combination of imaging modalities with freely available software and protocols may open up completely new avenues for the investigation of many important biogeochemical and physical processes in structured soils.
13974. 题目: Reactive iron and iron‐bound organic carbon in surface sediments of the river‐dominated Bohai Sea (China) versus the southern Yellow Sea
期刊: Journal of Geophysical Research: Biogeosciences
作者: Di Wang, Mao‐Xu Zhu, Gui‐Peng Yang, Wei‐Wei Ma
摘要: Factors influencing reactive Fe cycling and its protection of organic carbon (OC) in sediments are poorly understood. Here we comparatively study Fe speciation and Fe‐associated OC (Fe‐OC) in surface sediments of the Bohai Sea (BHS) and southern Yellow Sea (SYS), two seas with common sediment sources but different depositional regimes. Though significant sequestration of highly reactive Fe (FeHR) is expected in the estuarine system stream from the river‐dominated BHS, this pool is, however, slightly enriched in the BHS sediments relative to their source material. This reconfirms a previous speculation of sedimentary FeHR enrichment in semi‐protected settings. Relative to the BHS, the SYS sediments are depleted of FeHR, despite common sediment sources of these two areas. Estuarine pre‐enrichment and subsequent redistribution of FeHR in the BHS, and aging of Fe‐bearing authigenic clays during transport from the BHS to the SYS are potential mechanisms for the depletion. The fractions (fFe‐OC) of Fe‐OC in total OC in sediments of the two seas are at the lower end for soils and sediments, indicating Fe being a minor “rusty sink”. 13CFe‐OC fractionations indicate preferential sequestration of terrestrial OC by Fe oxides in the BHS, in contrast with preferential retention of marine OC in the SYS. Different fractionations of 13CFe‐OC in the two seas are a net result of selective adsorption of OC by Fe oxides and selective stabilization of OC during Fe reductive dissolution. Preferential sequestration of terrestrial OC may exert an important influence on distribution and compositions of OC buried in the river‐dominated system.
13975. 题目: Effects of different types of biochar on the anaerobic digestion of chicken manure
期刊: Bioresource Technology
作者: Junting Pan, Junyi Ma, Xiaoxia Liu, Limei Zhai, Xihui Ouyang, Hongbin Liu
摘要: This study investigated the impact of different types of biochar on the anaerobic digestion (AD) of chicken manure. Wheat straw, discarded fruitwood, and air-dried chicken manure were pyrolysed at 350, 450, and 550 °C to generate biochar. A lab-scale batch anaerobic digestion experiment was conducted at 35±1 °C. Substantial improvements in methane production were observed for all nine types of biochar. With the production of 294 mL CH4/g VSadded, fruitwood char pyrolysed at 550 °C increased the methane yield by 69% from the control. Characteristic analysis indicated that fruitwood char pyrolysed at 550 °C exhibited the largest specific surface area and highest total ammonia nitrogen reduction capacity. The buffering capacity of the AD system was improved by the biochar through accelerating the transformation of macromolecular substances to dissolved substrates and reducing the contents of soluble salts, total ammonia nitrogen, and free ammonia.
13976. 题目: Rapid of cultivation dissimilatory perchlorate reducing granular sludge and characterization of the granulation process
期刊: Bioresource Technology
作者: Pengna Yin, Jianbo Guo, Shumin Xiao, Zhi Chen, Yuanyuan Song, Xioaning Ren
摘要: To remove high-strength perchlorate, dissimilatory perchlorate reducing granular sludge (DPR-GS) was first cultivated. Three identical UASB reactors were set up under different seed sludge and up-flow velocities (RAS: active sludge (AS) and constant up-flow velocities; RDGS: denitrifying granular sludge (DGS) and constant up-flow velocities; RDGS-f: DGS and fluctuating up-flow velocities). The AS in the RAS was completely granulated by day 117, while the DGS in the RDGS and RDGS-f were both shortened the granulation time to 99 days. In addition, the fluctuating up-flow velocity can better ensure rapid cultivation of DPR-GS. Removal of ClO4- loading rate with 7.20 kg/(m3·d) occurred in all three reactors. The results of extracellular polymeric substances (EPS) composition analysis indicated the polysaccharose (PS) promoted the formation of bio-aggregates, while the protein (PN) benefited the granulation of sludge. The analyses of the microbial communities indicated that Sulfurospirillum and Acinetobacter were the dominant dissimilatory perchlorate reducing bacteria.
13977. 题目: Fluvial organic carbon fluxes from oil palm plantations on tropical peatland
作者: Sarah Cook, Mick J. Whelan, Chris D. Evans, Vincent Gauci, Mike Peacock, Mark H. Garnett, Lip Khoon Kho, Yit Arn Teh, and Susan E. Page
摘要: Intact tropical peatlands are dense long-term stores of carbon. However, the future security of these ecosystems is at risk from land conversion and extensive peatland drainage. This can enhance peat oxidation and convert long-term carbon sinks into significant carbon sources. In Southeast Asia, the largest land use on peatland is for oil palm plantation agriculture. Here, we present the first annual estimate of exported fluvial organic carbon in the drainage waters of four peatland oil palm plantation areas in Sarawak, Malaysia. Total organic carbon (TOC) fluxes from the plantation second- and third-order drains were dominated (91%) by dissolved organic carbon (DOC) and ranged from 34.4±9.7Cm−2yr−1 to 57.7%, 16.3gCm−2yr−1 (±95% confidence interval). These fluxes represent a single-year survey which was strongly influenced by an El Ninõ event and therefore lower discharge than usual was observed. The magnitude of the flux was found to be influenced by water table depth, with higher TOC fluxes observed from more deeply drained sites. Radiocarbon dating on the DOC component indicated the presence of old (pre-1950s) carbon in all samples collected, with DOC at the most deeply drained site having a mean age of 735 years. Overall, our estimates suggest fluvial TOC contributes ∼ 5% of total carbon losses from oil palm plantations on peat. Maintenance of high and stable water tables in oil palm plantations appears to be key to minimising TOC losses. This reinforces the importance of considering all carbon loss pathways, rather than just CO2 emissions from the peat surface, in studies of tropical peatland land conversion.
13978. 题目: Nonnegligible role of biomass types and its compositions on the formation of persistent free radicals in biochar: Insight into the influences on Fenton-like process
期刊: Chemical Engineering Journal
作者: Danlian Huang, Hao Luo, Chen Zhang, Guangming Zeng, Cui Lai, Min Cheng, Rongzhong Wang, Rui Deng, Wenjing Xue, Xiaomin Gong, Xueying Guo, Tao Li
摘要: Biochar, a green material that possesses high catalytic potential due to its persistent free radicals (PFRs), has attracted increasing attention in the removal of refractory pollutants from water. The influences of biomass types (bamboo, corn stalk, and pig manure) and its compositions (metals and phenolic compounds) on the formation of PFRs in biochar were investigated by electron paramagnetic resonance (EPR). It was found that the amounts of PFRs in biochar would decrease sharply with the decrease of the initial metals and phenolic compounds existed in biomass, and the effect of metals contents on PFRs formation was much greater than that of phenolic compounds contents. This finding was supported by the results obtained from elemental analysis and molar H/C analysis of three types of biochar, which suggested that pig-manure biochar (PM500) had the highest concentrations of PFRs of 14.13 × 1018 spins·g−1 due to the high content of metals and phenolic compounds in pig manure. The EPR trapping experiment and Linear sweep voltammetry (LSV) measurements in biochar/H2O2 systems showed that OH was the dominant reactive radical and electrons transfer pathways might be responsible for the activation of H2O2 by biochar. Possible degradation pathways of the tetracycline in biochar/H2O2 systems were also proposed. Besides, high degradation efficiency and good stability were observed in real wastewater application of the PM500/H2O2 system. These findings would provide a clearer insight into the formation mechanisms of PFRs in biochar, and also present a better strategy for biochar preparation and application in Fenton-like system.
13979. 题目: Oxidation and reduction of redox-sensitive elements in the presence of humic substances in subsurface environments: A review
作者: Seyong Lee, Younghee Roh, Dong-Chan Koh
摘要: The oxidation and reduction (redox) processes of redox-sensitive elements (RSE) in the presence of humic substances (HS) have become a significantly important issue in the terms of biogeochemical cycles. Redox processes are crucial for determining the speciation, mobility, toxicity, and bioavailability of RSE in natural environments. It is known that HS act as an effective redox mediator for accepting and donating electrons, and thereby transfers them to RSE. We review the recent progress in the field of the redox processes of RSE including As, Cr, Cu, Fe, Hg, and Se in the presence of HS. The extent and rate of the redox processes of these RSE are significantly affected by the concentration of functional groups and the chemical composition of HS. In subsurface environments, pH, ionic strength, and the presence of competitive components, microorganisms, and oxygen need to be considered to elucidate the redox processes of RSE in the presence of HS. In addition, improved analytical techniques for the characterization of HS has the potential to advance the study on the redox processes of RSE in the presence of HS. It may contribute to understanding the mechanism for the redox processes between RSE and HS in the biogeochemical cycles.
13980. 题目: BiOCl facilitated photocatalytic degradation of atenolol from water: Reaction kinetics, pathways and products
作者: Jinyuan Hu, Xueping Jing, Li Zhai, Jing Guo, Kun Lu, Liang Mao
摘要: Atenolol (ATL), a kind of largely used beta-blockers, has been widely detected in the aquatic environment, which could cause adverse impact on human beings. In this study, bismuth oxychloride (BiOCl) photocatalyst was synthesized and applied to remove ATL in the aqueous system under simulated natural light. Emphasis was laid on the reaction kinetics and the impact of natural organic matter (NOM) (0–20 mg/L). Possible transformation pathways were systematically investigated based on identification of reaction products via liquid chromatography-mass spectrometry (LC-MS). As a consequence, BiOCl presents highly photocatalytic efficiency yielding up to nearly 100% ATL conversion after 60 min of interaction, together with fairly high photostability evidenced by considerably efficient removal of ATL after 10 catalytic cycles. Four kinds of possible products are detected using LC-MS in the process of reaction, indicating possible transformation ways of ATL photocatalysis. NOM has an inhibiting impact on the removal of ATL and influences the products distribution. This study provides an emerging nanocatalyst for ATL photodegradation and could eventually lead to development of novel methods to control pharmaceutical contamination in water.