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26501. 题目: Understanding the relations between soil organic matter fractions and N2O emissions in a long‐term integrated crop–livestock system
文章编号: N19040610
期刊: European Journal of Soil Science
作者: Juliana Hiromi Sato, Cícero Célio de Figueiredo, Robélio Leandro Marchão, Alexsandra Duarte de Oliveira, Lourival Vilela, Francisco Marcos Delvico, Bruno José Rodrigues Alves, Arminda Moreira de Carvalho
更新时间: 2019-04-06
摘要: The nitrous oxide (N₂O) emissions in agricultural systems are influenced by edaphoclimatic conditions, and the availability of soil organic matter (SOM) is a key factor. The objective of this study was to evaluate the accumulation of labile and stable SOM fractions and possible relations with N₂O emissions using a multivariate approach in a 24‐year integrated crop–livestock experiment in the Cerrado region. The management systems consisted of: continuous cropping under no tillage (CC‐NT), continuous cropping under annual heavy disc harrow (CC‐CT), an integrated crop–livestock system under no tillage (CLS‐NT) and an adjacent area of native Cerrado as reference. The cumulative N₂O emissions were quantified over a period of 146 days, throughout the cultivation of sorghum (Sorghum bicolor (L.) Moench). Labile and stable soil carbon (C) fractions and C contents in classes of aggregates (macroagreggates > 0.250 mm and microagreggates < 0.250 mm) were determined. The cumulative N₂O emissions were larger in the CC‐CT system, intermediate in the CC‐NT and CLS‐NT systems, and smaller in the Cerrado. The decomposition of crop residues during the crop succession (first and second crop seasons) and the presence of a grass forage (with grazing and not grazed) in both systems (CLS‐NT and CC‐NT, respectively) explain the differences in N₂O fluxes between the land uses. Smaller cumulative N₂O emissions were observed in the integrated system (CLS‐NT), which could be attributed to the greatest increase in soil C in its most stable SOM fractions (fulvic acid) and occluded in microaggregates. This confirms the hypothesis that the accumulation of C in the most stable SOM fractions of the soil, unavailable to the microbiota, results in smaller N₂O emissions. Principal component analysis also revealed that aggregation is a key attribute that correlates with soil N₂O emissions. Thus, conservation systems such as CLS‐NT had larger average diameter of aggregates and the smallest N₂O emissions among the agroecosystems.

26502. 题目: Aquatic biomarkers record Pleistocene environmental changes at Paleolake Olduvai, Tanzania
文章编号: N19040609
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Devon E. Colcord, Andrea M. Shilling, Katherine H. Freeman, Jackson K. Njau, Ian G. Stanistreet, Harald Stollhofen, Kathy D. Schick, Nicholas Toth, Simon C. Brassell
更新时间: 2019-04-06
摘要: Several hypotheses invoke climatic variability as a driving force for hominin evolution. Thus, high-resolution records of climate and environmental variability from anthropologically significant locations can help test these hypotheses. Sedimentary sequences recovered by the Olduvai Gorge Coring Project (OGCP) help evaluate climatic and environmental changes at Olduvai Gorge, Tanzania through the analyses of various biogeochemical proxies. The stratigraphic sequence of OGCP Core 2A can be correlated with horizons associated with hominins and is chronologically constrained by distinctive dated horizons, such as the Bed I Basalt and Tuff IB. The lacustrine interval from 76.6 to 86.9 m depth is ideally suited for high-resolution analyses of biogeochemical proxies as it is rich in organic carbon (>1%TOC). The hydrogen isotopic composition of nC₃₁ in this interval of OGCP Core 2A records the effects of precession-driven wet-dry cycles on the terrestrial environment that led to alternations between woodland and grassland ecosystems, comparable to those documented by previous investigations of outcrop analogues at Olduvai. Here, we examine stratigraphic variations in the abundance of biomarkers (C₂₈ steradienes, C₁₇ and C₂₃ n-alkanes, C₂₇ and C₂₈ A-norsteranes, fern-8-ene, and chromans) derived from aquatic organisms (algae, cyanobacteria, sponges, macrophytes, etc.) to determine the response of Paleolake Olduvai to climate variability. In general, these aquatic biomarkers reflect the productivity of the lake environment and exhibit the same precession-driven wet-dry cycles recorded by terrestrial biogeochemical signatures. However, they also provide evidence of abrupt (<~300 yr) changes in lake level and corresponding aquatic communities superimposed on the longer-term Milankovitch cycles. Thus, evidence for climatic variability is manifested through the pacing and intensity of changes in both terrestrial and aquatic ecosystems, but the different rates of the responses on land and in the aquatic environment potentially had a complex influence on water and food resources that were important factors for hominin habitation and evolution.

26503. 题目: Impact of hydrotechnical works on outflow of mercury from the riparian zone to a river and input to the sea
文章编号: N19040608
期刊: Marine Pollution Bulletin
作者: Dominika Saniewska, Karolina Gębka, Magdalena Bełdowska, Grzegorz Siedlewicz, Jacek Bełdowski, Bartłomiej Wilman
更新时间: 2019-04-06
摘要: The aim of this research was to assess the impact of hydrotechnical works within the riverbed and riparian zone on the mobility of mercury in soil and its outflow to the river and the sea. Deepening and reconstruction of the riverbed or the cutting of reeds, influenced the fate of mercury in the river system. However, only activitis that disturbed the riperian zone increased mobilization of Hg in soils. Hg transformations in these places were controled by inflow of fresh organic matter in soil and sediments as well as by oxidation-reduction potential. In areas where reducing conditions occurred, mercury released from the soil was incorporated into the sediment. However, in areas where oxidizing conditions prevailed in the sediment, mercury flowing out of the soil occurred mainly in dissolved form and most of it was transported downstream from where it could reach the sea.
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26504. 题目: The behaviour of organic matter in hybrid water treatment system
文章编号: N19040607
期刊: Separation and Purification Technology
作者: Kazuhisa Mimura, Youichiro Takahashi, Shinichi Takanashi, Hiroshi Deguchi
更新时间: 2019-04-06
摘要: The removal of organic matter is a fundamental process in sewage treatment. Small scale sewage treatment plants, in particular, demand low cost and easy operation and maintenance. It is said that a hybrid water treatment system incorporating more physicochemical than biological processes for the removal of organic matter can be more convenient and incur less cost compared with a conventional activated sludge systems. Therefore, in this study, we propose a hybrid water treatment system equipped with a jet mixed separator (JMS), which is a type of pre-coagulation-sedimentation tank, and an aerobic moving bed biofilter (MBB). We then investigate the behaviour of particulate and soluble organic matter and the oxygen consumption by the biofilm in this hybrid system. The results indicate that the addition of the poly silicate iron coagulant in JMS increases the quantity of removed organic matter by approximately 30% compared with the process without coagulant, and that the majority of the removed organic matter is soluble. That is, the JMS effectively reduced the organic matter that can be eliminated only by biological treatment, and not by mechanical treatment. The residual organic matter of JMS was removed from the liquid phase within an hour, which is the hydraulic retention time (HRT) of MBB, and the removed soluble organic matter was almost perfectly biodegraded in the biofilm within a day. That is, MBB could continuously operate without excess growth of microorganisms as long as the filtering was working properly. Thus, the hybrid system is expected to maximize the performance of MBB.

26505. 题目: Carbon uptake in surface water food webs fed by palaeo‐groundwater.
文章编号: N19040606
期刊: Journal of Geophysical Research: Biogeosciences
作者: Debashish Mazumder, Neil Saintilan, Suzanne Hollins, Karina Meredith, Geraldine Jacobsen, Tsuyoshi Kobayashi, Li Wen
更新时间: 2019-04-06
摘要: The use of ¹⁴C to elucidate sources of carbon within freshwater aquatic ecosystems is challenging the assumption that modern autochthonous carbon dominates energy flows. We measured the uptake of old carbon through several trophic levels of a wetland fed by groundwater of the Great Artesian Basin (GAB), Australia, the largest artesian basin in the world. Stable isotopes (δ¹³C and δ¹⁵N) and radiocarbon (¹⁴C) were used to quantify food chain links and connection between groundwater and surface water food webs. Our results suggest that old groundwater was the dominant carbon source even at the highest trophic levels, with predatory fish returning apparent carbon ages of up to 11 ka. Stable isotope analysis (δ¹³C and δ¹⁵N) identified trophic links between fish, aquatic insects and algae with smaller contributions from particulate organic matter (POM) to the food webs. As natural mound springs and associated wetlands are the only source of reliable water during dry periods over vast areas of the western GAB, the result has potential implications for the interpretation of archaeological artefacts associated with indigenous passage within the interior.

26506. 题目: Postfire Soil Carbon Accumulation Does Not Recover Boreal Peatland Combustion Loss in Some Hydrogeological Settings
文章编号: N19040605
期刊: Journal of Geophysical Research: Biogeosciences
作者: R. C. Ingram, P. A. Moore, S. Wilkinson, R. M. Petrone, J. M. Waddington
更新时间: 2019-04-06
摘要: Deep peat burning at the interface between subhumid Boreal Plains (BP) peatlands and forestlands (margin ecotones) in some hydrogeological settings has brought into question the long‐term stability of these peatlands under current and future predicted climate. Small peatlands located at midtopographic positions on coarse sediments have been identified as hot spots for severe burning, as these peatland margins are not regularly connected to regional groundwater flow. The ability of these peatland systems to recover carbon lost from both the interior and margin within the fire return interval, however, has not yet been investigated. Here we examine peatland soil carbon accumulation along a chronosequence of time since fire for 26 BP ombrotrophic bogs located across a range of hydrogeological settings. Soil organic carbon accumulation following wildfire does not appear to be influenced by hydrogeological setting; however, the ability of a peatland to recover the quantity of carbon lost within the fire return interval is dependent on the amount of carbon that was released through smoldering, which is influenced by hydrogeological setting for peatland margins. Based on published measurements of organic soil carbon loss during wildfire and our soil carbon accumulation rates, we suggest that peatlands located at topographic lows on coarse‐grained glaciofluvial outwash sediments or on low‐relief, fine‐grained sediment deposits from glaciolacustrine or subglacial paleoenvironments are currently resilient to wildfire on the BP landscape. Peatlands that experience severe smoldering at the margins, such as ephemerally perched systems on glaciofluvial outwash sediments, will likely undergo permanent loss of legacy carbon stores.

26507. 题目: Grazing and enclosure alter the vertical distribution of organic nitrogen pools and bacterial communities in semiarid grassland soils
文章编号: N19040604
期刊: Plant and Soil
作者: Huanhe Wang, Jiangye Li, Qichun Zhang, Jun Liu, Bo Yi, Yong Li, Jingwen Wang, Hongjie Di
更新时间: 2019-04-06
摘要: Background and aims: Different grazing management practices have a significant impact on the sustainability of grassland ecosystems. This study invested the vertical distribution of soil nitrogen (N) forms and soil microbial community structures in a semiarid grassland ecosystem under different grazing management practices in Inner Mongolia. Methods: Soil samples were collected from three semiarid grassland plots subjected to different long-term management practices namely, free grazing (FG) and two different periods of enclosure (E83, enclosed since 1983 and E97, enclosed since 1997). The soil organic nitrogen (N) pools were analyzed by classical methods, and the bacterial community was assessed by PCR-DGGE and high-throughput sequencing. Results: The surface soil N-supplying capacity was in the order of E97 ≥ E83 ≥ FG. The soil ammonium N, amino N, and N-supplying capacity were greater in the enclosed plots than in the FG plot. Additionally, the 0–40-cm soil layer showed the influence of different management practices on the soil properties. The structure and diversity of the soil microbial community also varied with the management type. The soil organic N composition was significantly related to the soil bacterial community structure and microbial categories. Conclusions: An appropriate number of years of fencing helps to improve the soil surface nutrient status, whereas overgrazing and prolonged enclosure are not conducive to the restoration of soil nutrients. Different grazing management practices can affect the microbial community structure and turnover of soil N in grasslands.

26508. 题目: Are nanoplastics able to bind significant amount of metals? The lead example
文章编号: N19040603
期刊: Environmental Pollution
作者: Mélanie Davranche, Cloé Veclin, Anne-Catherine Pierson-Wickmann, Hind El Hadri, Bruno Grassl, Laura Rowenczyk, Aline Dia, Alexandra Ter Halle, Florent Blancho, Stephanie Reynaud, Julien Gigault
更新时间: 2019-04-06
摘要: The nanoscale size of plastic debris makes them potential efficient vectors of many pollutants and more especially of metals. In order to evaluate this ability, nanoplastics were produced from microplastics collected on a beach exposed to the North Atlantic Gyre. The nanoplastics were characterized using multi-dimensional methods: asymmetrical flow field flow fractionation and dynamic light scattering coupled to several detectors. Lead (II) adsorption kinetics, isotherm and pH-edge were then carried out. The sorption reached a steady state after around 200 min. The maximum sorption capacity varied between 97% and 78.5% for both tested Pb concentrations. Lead (II) adsorption kinetics is controlled by chemical reactions with the nanoplastics surface and to a lesser extent by intraparticle diffusion. Adsorption isotherm modeling using Freundlich model demonstrated that NPG are strong adsorbents equivalent to hydrous ferric oxides such as ferrihydrite (log Kadsfreundlich against 11.76 for NPG and ferrihydrite, respectively). The adsorption is dependent upon pH, in response to the Pb(II) adsorption by the oxygenated binding sites developed on account of the surface UV oxidation under environmental conditions. They could be able to compete with Fe or humic colloids for Pb binding regards to their amount and specific areas. Nanoplastics could therefore be efficient vectors of Pb and probably of many other metals as well in the environment.
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26509. 题目: Succession of microbial community during vigorous organic matter degradation in the primary fermentation stage of food waste composting
文章编号: N19040602
期刊: Science of The Total Environment
作者: Kiyohiko Nakasaki, Hidehira Hirai, Hiroshi Mimoto, Tran Ngoc Minh Quyen, Mitsuhiko Koyama, Kazuhiro Takeda
更新时间: 2019-04-06
摘要: Composting is an advantageous method for recycling organic waste and produces organic fertilizer. Composting involves many types of microorganisms that construct complex microbial ecosystems. No previous research has attempted to determine which microorganisms commonly appear in successful (i.e. well-stabilized) composting. To produce well-stabilized compost within a short time period, accelerating organic matter decomposition during primary fermentation of composting is helpful. In this study, microbial succession during primary fermentation of composting was examined with changes in its physicochemical parameters, to identify microorganisms common in the final stage of primary fermentation in successful composting with thorough degradation of organic matter. Composting of model food wastes (mixture of commercial rabbit food and cooked rice) was conducted by inoculating organic acid-degrading mesophilic yeast and maintaining the composting temperature at 40 °C for different time periods as compost warmed, and finally maintaining it at a thermophilic temperature of 60 °C. Canonical correspondence analysis (CCA) showed clear correlations among measured parameters of pH, temperature, CO₂ evolution rate, cell density of thermophilic bacteria, and microbial consortium. Moreover, high-throughput DNA analysis of compost bacteria revealed that Bacillales were dominant throughout the composting process; however, types of bacteria belonging to the order Bacillales group changed significantly as the degradation of organic matter progressed. In addition, the number of a certain group of Bacillales increased together with Symbiobacterium, a commensal bacterium, and these increased in the final stage of composting when organic matter was thoroughly degraded, irrespective of composting conditions. This finding would be useful in identifying an indicator microorganism for well-stabilized compost.
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26510. 题目: Transformation of dissolved organic matter during full-scale treatment of integrated chemical wastewater: Molecular composition correlated with spectral indexes and acute toxicity
文章编号: N19040601
期刊: Water Research
作者: Bingliang Zhang, Chao Shan, Zhineng Hao, Jingfu Liu, Bing Wu, Bingcai Pan
更新时间: 2019-04-06
摘要: As one of the key economic modes in China, chemical industry park (CIP) has made great contribution to the Chinese rapid economic growth. Concomitantly, how to effectively and safely dispose of the CIP wastewater (CIPWW) has been an unavoidable issue. Molecular transformation of dissolved organic matter (DOM) in CIPWW treatment is essential to optimize the employed process and to provide solid basis for risk evaluation of the discharged effluent as well. In this study, electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) was used to characterize the molecular transformation of DOM during full-scale treatment of integrated chemical wastewater in a centralized wastewater treatment plant (CWWTP), where the combined process follows hydrolysis/acidification (HA)-flocculation/precipitation (FP)-A²/O-membrane bioreactor (MBR)-ultrafiltration/reverse osmosis (UF/RO). Compared to municipal wastewater, DOM in CIPWW exhibited higher unsaturation degree, lower molecular weight, and higher toxicity. In FP unit, DOM of C_<24 and higher nominal oxidation state of carbon (NOSC) values was preferentially removed. The HA and anaerobic units are capable of significantly degrading DOM, resulting in great changes in molecular composition of DOM. However, the anoxic, oxic, and MBR units only lead to a slight change of the molecular formulae. The terminal units of UF and RO can remove most DOM, with the DOC declining by 19.2% and 94.6% respectively. The correlation between spectral indexes and acute toxicity with the molecular formulae of DOM suggested that polyphenols and highly unsaturated phenols were positively correlated with SUVA₂₅₄. In addition, both compounds (0.32 < O/C < 0.63) as well as the aliphatic ones (0.22 < O/C < 0.56) presented positive correlation with acute toxicity. Further, the pairwise correlation analysis illustrated that SUVA₂₅₄, O/C_wa, double bond equivalence (DBE_wa), and NOSC_wa were positively correlated with each other, whereas the acute toxicity was positively correlated with humification index (HIX), O/C_wa, and DBE_wa.
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26511. 题目: Fate of Trace Organic Compounds in the Hyporheic Zone: Influence of Retardation, the Benthic Biolayer, and Organic Carbon
文章编号: N19040506
期刊: Environmental Science & Technology
作者: Jonas L. Schaper, Malte Posselt, Camille Bouchez, Anna Jaeger, Gunnar Nuetzmann, Anke Putschew, Gabriel Singer, Joerg Lewandowski
更新时间: 2019-04-05
摘要: The fate of 28 trace organic compounds (TrOCs) was investigated in the hyporheic zone (HZ) of an urban lowland river in Berlin, Germany. Water samples were collected hourly over 17 h in the river and in three depths in the HZ using minipoint samplers. The four relatively variable time series were subsequently used to calculate first-order removal rates and retardation coefficients via a one-dimensional reactive transport model. Reversible sorption processes led to substantial retardation of many TrOCs along the investigated hyporheic flow path. Some TrOCs, such as dihydroxy-carbamazepine, O-desmethylvenlafaxine, and venlafaxine, were found to be stable in the HZ. Others were readily removed with half-lives in the first 10 cm of the HZ ranging from 0.1 ± 0.01 h for iopromide to 3.3 ± 0.3 h for tramadol. Removal rate constants of the majority of reactive TrOCs were highest in the first 10 cm of the HZ, where removal of biodegradable dissolved organic matter was also the highest. Because conditions were oxic along the top 30 cm of the investigated flow path, we attribute this finding to the high microbial activity typically associated with the shallow HZ. Frequent and short vertical hyporheic exchange flows could therefore be more important for reach-scale TrOC removal than long, lateral hyporheic flow paths.

26512. 题目: Dissolved organic matter characteristics of deciduous and coniferous forests with variable management: different at the source, aligned in the soil
文章编号: N19040505
期刊: Biogeosciences
作者: Lisa Thieme, Daniel Graeber, Diana Hofmann, Sebastian Bischoff, Martin T. Schwarz, Bernhard Steffen, Ulf-Niklas Meyer, Martin Kaupenjohann, Wolfgang Wilcke, Beate Michalzik, Jan Siemens
更新时间: 2019-04-05
摘要: Dissolved organic matter (DOM) is part of the biogeochemical cycles of carbon and nutrients, carries pollutants and drives soil formation. The DOM concentration and properties along the water flow path through forest ecosystems depend on its sampling location and transformation processes. To improve our understanding of the effects of forest management, especially tree species selection and management intensity, on DOM concentrations and properties of samples from different ecosystem fluxes, we studied throughfall, stemflow, litter leachate and mineral soil solution at 26 forest sites in the three regions of the German Biodiversity Exploratories. We covered forest stands with three management categories (coniferous, deciduous age class and unmanaged beech forests). In water samples from these forests, we monitored DOC concentrations over 4 years and characterized the quality of DOM with UV-vis absorption, fluorescence spectroscopy combined with parallel factor analysis (PARAFAC) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Additionally, we performed incubation-based biodegradation assays. Multivariate statistics revealed strong significant effects of ecosystem fluxes and smaller effects of main tree species on DOM quality. Coniferous forests differed from deciduous forests by showing larger DOC concentrations, more lignin- and protein-like molecules, and fewer tannin-like molecules in throughfall, stemflow, and litter leachate. Cluster analysis of FT-ICR-MS data indicated that DOM compositions, which varied in aboveground samples depending on tree species, become aligned in mineral soil. This alignment of DOM composition along the water flow path in mineral soil is likely caused by microbial production and consumption of DOM in combination with its interaction with the solid phase, producing a characteristic pattern of organic compounds in forest mineral soils. We found similarly pronounced effects of ecosystem fluxes on the biodegradability of DOM, but surprisingly no differences between deciduous and coniferous forests. Forest management intensity, mainly determined by biomass extraction, contribution of species, which are not site-adapted, and deadwood mass, did not influence DOC concentrations, DOM composition and properties significantly.

26513. 题目: Multidecadal persistence of organic matter in soils: multiscale investigations down to the submicron scale
文章编号: N19040504
期刊: Biogeosciences
作者: Suzanne Lutfalla, Pierre Barré, Sylvain Bernard, Corentin Le Guillou, Julien Alléon, Claire Chenu
更新时间: 2019-04-05
摘要: Minerals, particularly clay-sized minerals, protect soil organic matter (SOM) from decomposition by microorganisms. Here we report the characterization of SOM and the associated minerals over decades of biodegradation, in a French long-term bare fallow (LTBF) experiment started in 1928. The amounts of carbon (C) and nitrogen (N) in the study area declined over time for six fractions (sand, coarse silt, fine silt, coarse clays, intermediate clays, and fine clays). The C:N ratios of SOM associated with silt fractions remained constant, whereas the ratios significantly decreased in clays, reaching very low values in intermediate and fine clays (C:N < 5) after 8 decades of LTBF conditions. X-ray absorption spectroscopy revealed the following: (i) bulk-scale SOM chemical speciation remained almost constant; (ii) submicron particulate OM was present in coarse clays, even after 79 years of LTBF conditions; and (iii) illite particles became progressively SOM-free with time, whereas mixed-layer illite/smectite and smectites were always associated with OM throughout the bare fallow treatment. In summary, these results suggest that clay-sized minerals preferentially protect N-rich SOM and that smectites and mixed-layer illite/smectite seem to protect associated OM more effectively than pure illites.

26514. 题目: Molecular Hysteresis: Hydrologically Driven Changes in Riverine Dissolved Organic Matter Chemistry during a Storm Event
文章编号: N19040503
期刊: Journal of Geophysical Research: Biogeosciences
作者: Sasha Wagner, Jennifer Hoyle Fair, Serena Matt, Jacob D. Hosen, Peter Raymond, James Saiers, James B. Shanley, Thorsten Dittmar, Aron Stubbins
更新时间: 2019-04-05
摘要: Hydrological events, driven by rainfall, control the amount and composition of dissolved organic matter (DOM) mobilized through river networks. In forested watersheds, the concentration, composition, and reactivity of DOM exported changes as baseflow transitions to storm flow, with major implications to downstream biogeochemistry. Hysteresis describes an observed difference between in‐stream solute concentration/signal and discharge. By studying the relationship between DOM and stream discharge, we refine our understanding of the environmental and hydrological factors that influence the quantity and quality of stream DOM. The main objective of this study was to track hysteretic changes in riverine DOM molecular composition during storm events. Samples were collected from nested sites within the Passumpsic River catchment (Vermont, USA), a tributary of the Connecticut River. High‐resolution monitoring of fluorescent DOM (via in situ sensors) and automated collection of discrete samples captured short‐term, hydrologically driven variations in DOM concentration and composition. Ultrahigh‐resolution mass spectrometry revealed an enrichment in aliphatic compounds at storm onset, while aromatic and polyphenolic compounds were more enriched at peak discharge. Molecular hysteresis patterns were similar across stream orders, indicating that fresh, terrigenous DOM is quickly shunted downstream, through the river network, during pulses of high discharge.

26515. 题目: Effects of different biochar amendments on carbon loss and leachate characterization from an agricultural soil
文章编号: N19040502
期刊: Chemosphere
作者: Xing Ya Yang, Kwang-Hyeon Chang, You Jin Kim, Jin Zhang, Gayoung Yoo
更新时间: 2019-04-05
摘要: Selection of an appropriate biochar as a soil amendment requires a thorough investigation of the effects on soil ecosystems and adjacent water systems via leaching. Different biochar characteristics influence retention or leaching of different soil and biochar components. A lab lysimeter study was conducted to investigate carbon (C) balance and leachate quality with biochar additions. Biochar made from wood pellets (WP) and sewage sludge (SS) produced at 400 °C (WP400 and SS400) and 700 °C (WP700 and SS700), respectively, were applied to silt loam soil at an application rate of 4%. Fluorescence excitation-emission spectrophotometry (EEMs) was utilized to understand the compositional changes in leachate dissolved organic carbon (DOC). Our results show that DOC contributed the largest portion of C leaching loss. The WP treatments increased DOC mass loss, but did not significantly change leachate DOC quality. SS400, in comparison, increased mass loss of DOC and SS700 decreased it probably due to its higher adsorptive capacity to DOC. Unlike WP treatments, SS treatments significantly changed leachate DOC quality. Chemical oxygen demand (COD) was reduced with SS400 and SS700 biochar additions, which is assumed to be related to SS biochar's high oxygen-containing surface functional groups. Reduction in total nitrogen (TN) leaching by WP700 and SS700 treatments might be related to the higher micropore surface area. Over all, our findings imply that changes in the different components of the leachate from biochar-amended soil are related to different biochar properties, such as labile matter content, total surface area, micropore volume and cation exchange capacity.

26516. 题目: Effects of soil organic carbon (SOC) content and accessibility in subsoils on the sorption processes of the model pollutants nonylphenol (4-n-NP) and perfluorooctanoic acid (PFOA)
文章编号: N19040501
期刊: Science of The Total Environment
作者: Melanie Martz, Jannis Heil, Bernd Marschner, Britta Stumpe
更新时间: 2019-04-05
摘要: Subsoils control the release of hydrophobic pollutants to groundwater systems, but the role of subsoil soil organic carbon (SOC) in sorption processes of hydrophobic organic pollutants remains unclear. Thus, this study aimed to understand the role of subsoil SOC in sorption processes of 4-n-nonylphenol (NP) and perfluorooctanoic acid (PFOA) as model pollutants. To characterize the sorption behavior of NP and PFOA, 42 sub- and 54 topsoil samples were used for batch experiments. Differences in NP and PFOA sorption between sub- and topsoil samples and its mechanisms were identified using multiple regression analysis. Generally, the sorption of NP and PFOA was linear in all samples. The sorption of NP to soil samples (log_KD = 1.78–3.68) was significantly higher and less variable than that of PFOA (log_KD = −0.97–1.44). In topsoils, SOC content had the highest influence on NP and PFOA sorption. For NP, hydrophobic interactions between NP and SOC were identified as the most important sorption mechanism. For PFOA, hydrophobic as well as electrostatic interactions were determined depending on soil pH. In subsoils, the relevance of SOC content for pollutant sorption decreased drastically. For NP, not SOC content but rather SOC quality was relevant in SOC poor subsoils. For PFOA, clay and iron oxide content were found to be relevant for pollutant interactions with the solid phase. Thus, especially in SOC depleted subsoils, the sorption potential for PFOA remained unpredictable.
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26517. 题目: Ball-milled biochar for alternative carbon electrode
文章编号: N19040410
期刊: Environmental Science and Pollution Research
作者: Honghong Lyu, Zebin Yu, Bin Gao, Feng He, Jun Huang, Jingchun Tang, Boxiong Shen
更新时间: 2019-04-04
摘要: Ball-milled biochars (BM-biochars) were produced through ball milling of pristine biochars derived from different biomass at three pyrolysis temperatures (300, 450, and 600 °C). The results of scanning electron microscopic (SEM), surface area, hydrodynamic diameter test, and Fourier transform infrared spectroscopy (FTIR) revealed that BM-biochars had smaller particle size (140–250 nm compared to 0.5–1 mm for unmilled biochar), greater stability, and more oxygen-containing functional groups (2.2–4.4 mmol/g compared to 0.8–2.9 for unmilled biochar) than the pristine biochars. With these changes, all the BM-biochar-modified glassy carbon electrodes (BM-biochar/GCEs) exhibited prominent electrochemical properties (e.g., ΔE_p of 119–254 mV compared to 850 mV for bare GCE). Cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) show that ball-milled 600 °C biochar/GCE (BMBB600/GCE and BMBG600/GCE) had the smallest peak-to-peak separation (ΔE_p = 119 and 132 mV, respectively), series resistance (R_S = 88.7 and 89.5 Ω, respectively), and charge transfer resistance (R_CT = 1224 and 1382 Ω, respectively), implying its best electrocatalytic activity for the reduction of Fe(CN)₆³⁻. It is supposed that the special structure (i.e., internal surface area, pore volume, oxygen-containing functional groups, and graphitic structure) facilitates the electron transfer and reduces interface resistance. Economic cost of BM-biochar/GCE was 1.97 × 10⁻⁷ USD/cm², much lower than that of a “low-cost platinum electrode” (0.03 USD/cm²). The results indicate potential application of the novel BM-biochar for low cost and high efficient electrodes.

26518. 题目: Formation of Nitrophenolic Byproducts during Heat-Activated Peroxydisulfate Oxidation in the Presence of Natural Organic Matter and Nitrite
文章编号: N19040409
期刊: Environmental Science & Technology
作者: Peizeng Yang, Yuefei Ji, Junhe Lu, Qingguo Huang
更新时间: 2019-04-04
摘要: Sulfate radical (SO₄^•–)-based advanced oxidation is a viable in situ remediation technology for degrading organic contaminants in the subsurface. In this study, we demonstrated that SO₄^•– could induce the activation of nitrite, an anion commonly present in the subsurface environment, leading to the formation of nitrophenolic byproducts. Fourier-transform infrared spectroscope and ¹⁵N nuclear magnetic resonance analysis revealed that the inorganic nitrite was incorporated into natural organic matter (NOM) to form organic nitrogen upon SO₄^•– oxidation. Nitrophenolic byproducts, including 2-hydroxy-5-nitrobenzoic acid, 4-nitrophenol, and 2,4-dinitrophenol, were identified using high-resolution mass spectrometry in combination with a ¹⁵N labeling technique. Formation of nitrated byproducts was ascribed to the scavenging of SO₄^•– by nitrite, which not only generated the nitrating agent NO₂^• but also inhibited the degradation of organic compounds, making them more available to the reactions with NO₂^•. The phenolic moieties in NOM served as the main reactive sites for NO₂^• attack. The nitration begins with H abstraction on the phenoxy oxygen, followed by the addition of another NO₂^• to its ortho or para site. Decarboxylation followed by NO₂^• addition can also generate nitrophenolic byproducts. To the best of our knowledge, this is the first study reporting the nitration of NOM and formation of toxic nitrophenolic byproducts during SO₄^•–-based oxidation. It sheds light on the potential risks of this technology in subsurface remediation practices.
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26519. 题目: Cellulose digestion abilities determine the food utilization of mangrove estuarine crabs
文章编号: N19040408
期刊: Estuarine, Coastal and Shelf Science
作者: Shun Kawaida, Kusuto Nanjo, Naoya Ohtsuchi, Hiroyoshi Kohno, Mitsuhiko Sano
更新时间: 2019-04-04
摘要: Food utilization and cellulose digestion abilities of six crab species were examined to clarify the mechanisms driving trophic and spatial segregation among species within a mangrove estuary on the Urauchi River, Iriomote Island, southern Japan. Dual stable isotope signatures (δ¹³C and δ¹⁵N) of dominant crab species inhabiting three microhabitats (bare sandy flat, bare muddy flat and mangrove forest) showed that most crab species, such as the soldier crab Mictyris guinotae and fiddler crab Gelasimus jocelynae, primarily assimilated microphytobenthos (MPB), while the sesarmid crab Parasesarma bidens inside the mangrove forest substantially utilized cellulose-rich mangrove detritus and leaf litter. Analyses of the chemical properties of sediment organic matter indicated that it comprised mainly mangrove detritus, which was more abundant on the muddy flat and in the forest compared to the sandy flat. In contrast, the standing stocks of MPB were at consistently low levels in each microhabitat, particularly inside the mangrove forest than on the bare flats. The enzyme assay revealed that P. bidens exhibited much higher cellulase activity, enabling the species to utilize refractory mangrove materials, whereas the other crab species with lower cellulase activity were highly dependent upon nutritious and easily degradable MPB, although the amount of the latter was largely limited in the mangrove estuary. These findings suggested that the assimilation efficiency of cellulose-rich plant materials as a carbon source, dependent upon the level of cellulase activity, essentially controls trophic and spatial segregation among crab species in the mangrove estuary. Given the greater biomass of plant detritus, it is likely that P. bidens plays an integral part in establishing the detritus food chain in the mangrove ecosystem through the effective digestion/assimilation of cellulose materials.
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26520. 题目: Effects of soil properties on the toxicity and bioaccumulation of lead in soil invertebrates
文章编号: N19040407
期刊: Environmental Toxicology and Chemistry
作者: RomanP Lanno, Koen Oorts, Erik Smolders, Katie Albanese, MJasim Chowdhury
更新时间: 2019-04-04
摘要: The present study examined the effects of soil physical and chemical properties on the toxicity of lead (Pb) to earthworms (Eisenia fetida) and collembolans (Folsomia candida), and on bioaccumulation of Pb by earthworms, in soils amended with Pb salts. Toxicity tests were conducted in seven soils varying in soil properties (pH: 4.7‐7.4, eCEC: 4‐42 cmol_c/kg, organic carbon: 10 – 50 g C/kg) that were leached and pH corrected after spiking with PbCl₂. EC50s based upon total soil Pb concentrations ranged from 35 to 5080 mg Pb/kg for earthworms and 389 to >7190 mg/kg for Collembola. Significant positive correlations were observed between log (EC50) for earthworm reproduction and log (eCEC, total C, exchangeable Ca and Mg, or clay content), but no significant correlations were observed between Pb toxicity to Collembola and soil properties. Expressing Pb dose as either the free ion (Pb²⁺) activity in pore water or as the measured dissolved porewater concentration of Pb did not explain differences in toxicity among soils. The bioaccumulation factors (BAFs) for Pb in earthworms ranged more than 10‐fold across six soil treatments, with a median of 0.16, and the BAF was significantly correlated with eCEC (p = 0.038, r = ‐0.84), but not with any other soil properties. Soil properties related to cation‐exchange capacity (eCEC, total C, exchangeable Ca and Mg, clay content) had a significant effect on Pb toxicity and bioaccumulation in earthworms, but no relationship was found for Collembola. CEC is a major soil property affecting the bioavailability of Pb and should be incorporated into any soil hazard assessment of Pb as a modifying factor of toxicity and bioaccumulation for earthworms.