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17301. 题目: Wheat straw biochar application increases ammonia volatilization from an urban compacted soil giving a short-term reduction in fertilizer nitrogen use efficiency
文章编号: N18111507
期刊: Journal of Soils and Sediments
作者: Haijun Sun, Hailin Zhang, Hongdong Xiao, Weiming Shi, Karin Müller, Lukas Van Zwieten, Hailong Wang
更新时间: 2018-11-15
摘要: Purpose: The potential for using biochar to reclaim degraded urban land into productive land needs to be verified to address the incipient loss of agricultural land. Materials and methods: A pot experiment was conducted to evaluate the effect of wheat straw biochar (with four application rates including 0, 0.5%, 1%, and 2% w/w biochar to soil) on selected soil properties and crop growth (paddy rice was grown followed by wheat) in a compacted urban homestead soil (Anthrosol). Nitrogen use efficiency and ammonia volatilization were determined using stable isotope methodologies. Results and discussion: Wheat straw biochar amendments elevated the soil pH, total C, and C/N ratio, and significantly lowered (P < 0.05) the soil bulk density by 12.0–17.7% with doses of 1–2%. Increasing doses of biochar (1–2%) increased ammonia volatilization by 91.4–107.0% during the flooded rice season, which resulted in significantly lower (P < 0.05) rice yield. This was reflected in the reduction of fertilizer ¹⁵N use efficiency, which was 32.6–76.0% lower (P < 0.05) than the control. However, the following wheat yield was significantly increased (P < 0.05) by 23.0% with 2% biochar amendment, while there were no differences in ammonia volatilization between biochar amendments and the control. Conclusions: Application of wheat straw biochar to a reclaimed urban Anthrosol increased seasonal flooded rice ammonia volatilization; however, no effect on ammonia volatilization was detected from the following aerobically grown wheat. The soils had a lower bulk density following biochar amendment and improved pH, which may have resulted in the higher wheat yield.

17302. 题目: Consistent proteinaceous organic matter partitioning into mineral and organic soil fractions during pedogenesis in diverse ecosystems
文章编号: N18111506
期刊: Biogeochemistry
作者: Jinyoung Moon, Kang Xia, Mark A. Williams
更新时间: 2018-11-15
摘要: Proteinaceous compounds are critical in soil organic matter (SOM) formation and persistence, but the partitioning into mineral-associated and organic forms during hundreds and thousands of years of pedogenesis are poorly understood across multiple climates and vegetation types. We investigated the partitioning of amino acids (AA) into mineral-bound (MB) and non-mineral associated organic (NMO) soil fractions to discern whether consistent patterns during ecosystem development were observed across two different climates (cool temperate continental, USA; and moist oceanic forests, New Zealand). Although each ecosystem retained unique soil AA signatures, consistent patterns in both systems were observed with three main findings. (1) Regardless of differences in climate and vegetation between the two ecosystems, AA consistently partitioned in similar ways into MB and NMO soil fractions. For example, Thr, Ser, and Asx were relatively more dominant in the NMO fraction while Arg, Lys, Cys, and Met were relatively more dominant in the MB soil fraction. (2) AA change, showed similar trends related to chemical groupings of positively-charged, polar aromatic, sulfur containing, and non-polar AAs across both ecosystems consistent with changing patterns of soil Fe and Al bearing minerals, such as an increasing weathering index (WI; Fe dithionite/total Fe) and losses of Fe and Al from surface soils during ecosystem development. (3) The pedogenic patterns of AA change, in each system paralleled biological transitions in bacterial communities, suggesting a linkage between the AA sources and the soil sink that contributes to soil organic N. This latter point contrasts with the potential for complete change in soil AA composition that could occur upon processing and binding in soil. Overall, the consistency in the types of AAs that partition into either MB or NMO soil fractions across locations provide evidence of similar processes that contribute to soil organic N accrual across soils. Some AA also appeared to be retained in soil by electrostatic forces, and AA–organic matter interactions, that need further study. Mineral–metal complexation of AAs with sulfur side chain groups, and non-polar interactions, respectively, provide examples of these potential mechanisms for study. The results not only support mechanisms of soil proteinacous organic matter chemistry being driven by the interactions with the soil matrix, acting as a “sink”, but also draw attention to the sources of organic matter (microbes, plants) in determining the composition of organic N in soil during pedogenesis.

17303. 题目: The Positive Fate of Biochar Addition to Soil in the Degradation of PHBV-Silver Nanoparticle Composites
文章编号: N18111505
期刊: Environmental Science & Technology
作者: Suely Patrı́cia Costa Gonçalves, Mathias Strauss, Diego Stéfani Teodoro Martinez
更新时间: 2018-11-15
摘要: The environmental contamination of soils by polymeric and nanomaterials is an increasing global concern. Polymeric composites containing silver nanoparticles (AgNP) are collectively one of the most important products of nanotechnology due to their remarkable antimicrobial activity. Biochars are a promising resource for environmental technologies for remediation of soils considering their high inorganic and organic pollutant adsorption capacity and microbial soil consortium stimulation. In this work we report, for the first time, the use of biochar material as a tool to accelerate the degradation of polyhydroxybutyrate-co-valerate (PHBV) and PHBV composites containing AgNP in a tropical soil system, under laboratory conditions. This positive effect is associated with microbial community improvement, which increased the degradation rate of the polymeric materials, as confirmed by integrated techniques for advanced materials characterization. The addition of 5–10% of sugarcane bagasse biochar into soil has increased the degradation of these polymeric materials 2 to 3 times after 30 days of soil incubation. However, the presence of silver nanoparticles in the PHBV significantly reduced the degradability potential of this nanocomposite by the soil microbial community. These results provide evidence that AgNP or Ag⁺ ions caused a decline in the total number of bacteria and fungi, which diminished the polymer degradation rate in soil. Finally, this work highlights the great potential of biochar resources for application in soil remediation technologies, such as polymeric (nano)material biodegradation.
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17304. 题目: Spatial variability in dissolved iron concentrations in the marginal and open waters of the Indian Ocean
文章编号: N18111504
期刊: Marine Chemistry
作者: Venkatesh Chinni, Sunil Kumar Singh, Ravi Bhushan, R. Rengarajan, V.V.S.S. Sarma
更新时间: 2018-11-15
摘要: We analyzed 28 full vertical profiles of dissolved iron (DFe) in the Indian Ocean (i.e., between 26°S – 20°N and 72°E – 105°E) during two research expeditions (SK-304: March–May 2013, SK-311: March–April 2014) as part of the GEOTRACES-India programme. Relatively high DFe concentrations in surface waters (≤10 m) were observed in the Arabian Sea (AS: 0.682 ± 0.033 nM, n = 2) and the Bay of Bengal (BoB: 0.439 ± 0.105 nM, n = 21) compared to the stations located south of the equator (0.271 ± 0.159 nM, n = 17). Higher DFe in the coastal stations is presumably sourced from the continental shelves. Depth profiles of DFe in the AS, BoB and Andaman Sea showed sub-surface maxima, coinciding with low dissolved oxygen (DO) concentrations. High DFe concentrations in sub-surface waters of the BoB and the Andaman Sea are attributed to desorption of soluble iron from resuspended sediments of the rivers and the remineralization of sinking particulate organic matter. We also observed a significant contribution of DFe from hydrothermal vents situated at the Central Indian ridge and subduction processes along the Java trench to pelagic waters of the Indian Ocean. Fe:C remineralization ratios of 3.92 ± 0.83, 5.88 ± 2.65, 8.96 ± 3.85 and 5.74 ± 3.06 μmol/ mol were observed in the Indian Ocean, BoB, AS and Andaman Sea, respectively. To assess the surface areas and deep water masses where DFe concentrations potentially limit phytoplankton growth (when reaching the surface) we subtracted the contribution of particulate organic matter remineralization to the DFe pool using the tracer Fe* (≈DFe–R_Fe:P(Phosphate)). Positive Fe* values in the intermediate waters suggest an external source for DFe, whereas negative Fe* values suggest the absence of such external inputs and/or removal by scavenging processes. Our results contribute to improved understanding of DFe distributions and their coupling with the ocean biogeochemical cycling of carbon and nitrogen in this region.

17305. 题目: Performance of a compost and biochar packed biofilter for gas-phase hydrogen sulfide removal
文章编号: N18111503
期刊: Bioresource Technology
作者: Jewel Das, Eldon R. Rene, Capucine Dupont, Adrien Dufourny, Joël Blin, Eric D. van Hullebusch
更新时间: 2018-11-15
摘要: The main aim of this study was to evaluate the performance of an aerobic biofilter packed with compost for the removal of gas-phase hydrogen sulfide (H₂S). After 52 d of operation, the biofilter was re-packed by replacing a certain portion (25%, v/v) of the existing compost with biochar and its performance was tested. The steady and transient performance of the biofilter was evaluated by varying the H₂S concentrations from 0.1 to 2.9 g m^-3 at an empty bed residence time (EBRT) of 119 and 80 s, respectively. The maximum elimination capacity (EC_max) of the compost and compost + biochar biofilter were ∼19 and 33 g m^-3 h^-1, respectively, with > 99% removal efficiency at an EBRT of 119 s. The compost biofilter showed a quick response to shock loads and the critical load to the biofilter during the shock loading step was ∼81 g m^-3 h^-1.
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17306. 题目: Electron accepting capacity of dissolved and particulate organic matter control CO₂ and CH₄ formation in peat soils
文章编号: N18111502
期刊: Geochimica et Cosmochimica Acta
作者: Chuanyu Gao, Michael Sander, Svenja Agethen, Klaus-Holger Knorr
更新时间: 2018-11-15
摘要: Peatlands are a major source of atmospheric CH₄. The availability of terminal electron acceptors largely affects the ratio of CO₂ to CH₄ formation under water-logged anoxic conditions in these systems. Although the importance of peat organic matter as an electron acceptor is increasingly recognized, the actual budgets of electron accepting capacities of dissolved and particulate organic matter remain poorly characterized. To address this research need, we incubated three different peat materials and linked changes in the electron accepting capacities (EAC) of peat organic matter (OM), including dissolved and particulate organic matter, to the observed CO₂ and CH₄ formation. Under anaerobic conditions, EAC_OM decreased inverse to non-methanogenic CO₂ formation. Only after utilizable EAC_OM was depleted did strictly methanogenic conditions evolve with equimolar CH₄ and CO₂ formation rates, as theoretically expected. The reduction of OM and the resultant decrease in EAC_OM explained between 26 to 56% of the non-methanogenic CO₂, which was between 5 to 39 % of total CO₂ produced. Compared to EAC_POM, EAC_DOM remained constant and may have served as a mediator in electron transfer to the POM. In summary, our study quantitatively demonstrated the important role of peat OM as terminal electron acceptor for anaerobic respiration in organic soils.

17307. 题目: Biochar additions alter phosphorus and nitrogen availability in agricultural ecosystems: A meta-analysis
文章编号: N18111501
期刊: Science of The Total Environment
作者: Si Gao, Thomas H. DeLuca, Cory C. Cleveland
更新时间: 2018-11-15
摘要: Biochar is a carbon (C) rich product of thermochemical conversion of organic material that is used as a soil amendment due to its resistance to decomposition and its influence on nutrient dynamics; however, individual studies on biochar effects on phosphorus (P) and nitrogen (N) have proven inconsistent. Herein, we performed a meta-analysis of 124 published studies to evaluate the influence of biochar on available P, microbial biomass P (MBP), and inorganic N (NO₃⁻-N and NH₄⁺-N) in global agricultural ecosystems. Overall, the results showed that biochar applications significantly increased surface soil available P by 45% and MBP by 48% across the full range of biochar characteristics, soil type, or experimental conditions. By contrast, biochar addition to soil reduced NO₃⁻-N concentrations by 12% and NH₄⁺-N by 11%, but in most cases biochar added in combination with organic fertilizer significantly increased soil NH₄⁺-N compared to controls. Biochar C:N ratio and biochar source (feedstock) strongly influenced soil P availability response to biochar where inorganic N was most influenced by biochar C:N ratio and soil pH. Biochar made from manure or other low C:N ratio materials, generated at low temperatures, or applied at high rates were generally more effective at enhancing soil available P. It is important, however, to note that most negative results were observed in short-term (<6 months) where long-term studies (>12 months) tended to result in neutral to modest positive effects on both P and N. This meta-analysis indicates that biochar generally enhances soil P availability when added to soils alone or in combination with fertilizer. These findings provide a scientific basis for developing more rational strategies toward widespread adoption of biochar as a soil amendment for agricultural P and N management.
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17308. 题目: The suitability of growing mulberry ( Morus alba L.) on soils consisting of urban sludge composted with garden waste: a new method for urban sludge disposal
文章编号: N18111413
期刊: Environmental Science and Pollution Research
作者: Liqing Si, Xiawei Peng, Jinxing Zhou
更新时间: 2018-11-14
摘要: Efficient disposal of urban sewage sludge, material that typically contains high concentrations of heavy metals, has become a significant concern worldwide. The empirical purpose of the current study is to investigate physical and chemical parameters of composted sludge and garden waste at different ratios. Results reveal that nutrient content has significantly increased after the application of composts as compared to the controlled sample. Composting garden waste with sewage sludge at a 1:1 ratio promoted plant growth and gradually showed superiority in the later period. The maximum plant height, total biomass, and crown width of mulberry trees increased by 12.1, 33.5, and 45.7%, respectively, compared with the control treatment. The bound to organic matter of Hg, Cr, and Pb in the sewage sludge increased after composting with garden waste, and the mulberry exhibited a high ability to accumulate Ni and Cd from the soil. Conclusively, compared to using the two soil mediums separately, composting garden waste and sewage sludge together is beneficial for soil improvement and vegetation growth.

17309. 题目: Natural levels and photo-production rates of hydrogen peroxide (H₂O₂) in Andean Patagonian aquatic systems: Influence of the dissolved organic matter pool
文章编号: N18111412
期刊: Chemosphere
作者: Patricia Elizabeth García, Claudia Queimaliños, María C. Diéguez
更新时间: 2018-11-14
摘要: In aquatic environments the reactive oxygen species hydrogen peroxide (H₂O₂) is produced through photochemical reactions involving chromophoric dissolved organic matter (CDOM). Andean Patagonian freshwaters experience challenging underwater UV levels, which promote high levels of photochemical weathering. In this investigation, we study natural H₂O₂ levels and experimentally address the photochemical formation of H₂O₂ in stream and lake water with a range of dissolved organic matter (DOM) concentrations and quality. The screening of different pristine aquatic systems of Patagonia revealed that H₂O₂ concentration fluctuates between 8 and 60 nM. Laboratory incubation of different water types in PAR + UV showed photo-production of H₂O₂. The H₂O₂ formation rate increased linearly with dissolved organic carbon (DOC) in streams (13.5–20.5 nM h^-1) and shallow lakes (25.7–37.8 nM h^-1). In contrast, the H₂O₂ formation rate in deep lakes was much lower (2.1–7.1 nM h^-1), and decreased with DOC. The natural potential for H₂O₂ formation was related to the concentration and quality of the DOM pool. At higher DOC levels, such as those present in shallow lakes, H₂O₂ production was directly related to DOC, whereas at low DOC levels in deep lakes and streams, two patterns were distinguished in relation to their DOM pool quality. Stream DOM, composed of high molecular weight/size humic compounds, proved to be a reactive substrate, as reflected by their high H₂O₂ formation rates. On the other hand, deep lake DOM, with its higher relative contribution of small and more processed compounds, was found to be a less reactive substrate, affording lower H₂O₂ formation rates.

17310. 题目: A phylogenetic analysis of conifer diterpenoids and their carbon isotopes for chemotaxonomic applications
文章编号: N18111411
期刊: Organic Geochemistry
作者: Aaron F. Diefendorf, Andrew B. Leslie, Scott L. Wing
更新时间: 2018-11-14
摘要: Plant-derived diterpenoids are commonly used as conifer-specific biomarkers and for chemotaxonomic assignment or confirmation. Numerous studies have reported on the utility of diterpenoids as chemotaxonomic indicators, but few have quantitatively analyzed diterpenoid concentrations, especially with respect to conifer phylogeny. In addition, the carbon isotope values (δ¹³C) of diterpenoids provide a means to track conifer-specific δ¹³C values, which is useful for tracking water availability and the carbon cycle. To expand on previous work, we measured diterpenoid concentrations and carbon isotopes of 43 conifer species, and Ginkgo biloba, collected at the University of California Botanical Garden at Berkeley. In this collection, all extant conifer families and almost two-thirds of extant genera are present, including many subtropical and Southern Hemisphere groups that were once common and widespread components of fossil assemblages. Overall, we found diterpenoid concentrations were highly variable among species and families. Despite this variability, there is coarse family-level phylogenetic structuring with the lowest concentrations in Pinaceae. When diterpenoid concentrations are fitted to a model of trait evolution (Brownian motion), we however find that there is no phylogenetic signal. In contrast, when terpenoids are analyzed by the proportion of diterpenoid compound structure classes (abietanes, labdanes, pimaranes, tetracyclics, and totarols/sempervirol), there was significant phylogenic signal for the abietane and tetracyclic structures. Diterpenoid biosynthetic carbon isotope fractionation, as expressed between diterpenoids and leaf tissue (ε_diterpenoid), also contained a phylogenetic signal, as well as the broad phylogenetic structuring observed in total diterpenoid concentrations. Overall, these results indicate that the Pinaceae is unique among conifer clades with respect to terpenoid structure classes, concentrations and ε_diterpenoid. When diterpenoids are applied to taxonomic assignment of fossils, it would be useful to combine several traits (concentration, proportion, and ε_diterpenoid). In this context, it should be possible to broadly distinguish three major conifer groups: Cupressaceae, Podocarpaceae and Pinaceae. However, based on these results, we recommend against assuming that closely related species have similar diterpenoid compositions.

17311. 题目: The occurrence of isorenieratane and 24-n-propylcholestanes in Paleogene lacustrine source rocks from the Dongying Depression, Bohai Bay Basin: Implications for bacterial sulfate reduction, photic zone euxinia and seawater incursions
文章编号: N18111410
期刊: Organic Geochemistry
作者: Huiyuan Xu, Simon C. George, Dujie Hou
更新时间: 2018-11-14
摘要: Lacustrine organic-rich source rocks (shales and mudstones) were examined to assess the depositional environment and organic input sources of the third and fourth members of the Eocene Shahejie Formation, Bohai Bay Basin, China. Major organic contributions to the Shahejie Formation from dinoflagellates, diatoms, Botryococcus and marine pelagophyte/chrysophyte algae were determined using n-alkane distributions, gammacerane index and diagnostic steranes. Traces of higher plant biomarkers suggest that terrigenous organic inputs were limited. The pervasive presence of β-carotane, aryl isoprenoids, paleorenieratane, renieratane, isorenieratane, 2α-methylhopanes and crocetane indicate significant organic contributions from bacterial communities including cyanobacteria, purple sulfur bacteria (Chromatiaceae), green sulfur bacteria (Chlorobiaceae), and sulfate-reducing bacteria. The extent of H₂S content, bacterial sulfate reduction, and photic zone euxinia (PZE) were evaluated by determining the aryl isoprenoids ratio (AIR: 0.7–9.0), the presence of isorenieratene derivatives, and the fate of sulfur in the water column. There was a decrease of PZE extent and duration from the northeast to the southwest of the palaeo-lake, and there was a decrease of water body salinity and bottom water anoxia from the fourth to the third member of the Shahejie Formation. Abrupt environmental perturbations in the third member of the Shahejie Formation are indicated not only by significant changes in parameters such as the pristane/phytane and β-carotane/n-C₂₀ alkane ratios, the gammacerane index, the isorenieratane/C₁₈ aryl isoprenoid, and the AIR, but also by the time lag in the expansion of cyanobacterial lineages after the expansion of purple/green sulfur bacteria, as well as seawater incursions. The unexpected occurrence of intact C₃₀ 4-desmethylsteranes (24-n-propylcholestanes) in the Shahejie Formation is first reported here, after very careful checking, and provides unambiguous biological evidence for at least two marine transgression events reaching the Eocene Dongying palaeo-lake. The organic enrichment of the petroleum source rocks in the Shahejie Formation is a consequence of combined indigenous lacustrine algal production, the constrained and favourable preservation conditions, and significant bacterial contributions and marine organic matter inputs to the lake.

17312. 题目: Rice straw biochar modified by aluminum chloride enhances the dewatering of the sludge from municipal sewage treatment plant
文章编号: N18111409
期刊: Science of The Total Environment
作者: Junyuan Guo, Shilin Jiang, Yujie Pang
更新时间: 2018-11-14
摘要: Enhancement of the dewatering of the sludge by using rice straw biochar (RSB) modified by aluminum chloride (AlCl₃) was investigated, and the possible enhancing mechanisms were discussed. Results showed that the settled volume after 30 min (SV₃₀%), specific resistance to filtration (SRF), moisture content (MC) and capillary suction time (CST) of the sludge were decreased and the net sludge solids yield (Y_N) was increased by the increasing raw or modified RSB, which indicated a higher sludge dewaterability. When the dosage of the modified RSB was adjusted to 0.3 g(RSB)/g(dry sludge), SV₃₀%, SRF, MC and CST were decreased to 79.8%, 1.2 × 10¹² m/kg, 81.4% and 38 s, respectively, Y_N was increased to 19.4 kg/(m²·h). Furthermore, performance of the modified RSB in the dewatering of the sludge was significantly better than that of the raw RSB. For the enhancing mechanisms, charge neutralization occurred when the modified RSB (loaded with positively charged aluminum species on its surface) was dosed into the sludge system, thus destroying the stable sludge colloidal system, thus far easier to congregate the sludge particles, which enhanced the dewatering of the sludge. Another main enhancing mechanism was that after conditioned by the modified RSB, certain skeleton structures were formed in sludge cake to make water pass through easily by decreasing the extracellular polymeric substances (EPS) of the sludge. We found that the effectiveness of using the modified RSB to enhance the dewatering of the sludge is substantial and promising.
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17313. 题目: Spatial modeling of litter and soil carbon stocks on forest land in the conterminous United States
文章编号: N18111408
期刊: Science of The Total Environment
作者: Baijing Cao, Grant M. Domke, Matthew B. Russell, Brian F. Walters
更新时间: 2018-11-14
摘要: Forest ecosystems contribute substantially to carbon (C) storage. The dynamics of litter decomposition, translocation and stabilization into soil layers are essential processes in the functioning of forest ecosystems, as these processes control the cycling of soil organic matter and the accumulation and release of C to the atmosphere. Therefore, the spatial distribution of litter and soil C stocks are important in greenhouse gas estimation and reporting and inform land management decisions, policy, and climate change mitigation strategies. Here we explored the effects of spatial aggregation of climatic, biotic, topographic and soil variables on national estimates of litter and soil C stocks and characterized the spatial distribution of litter and soil C stocks in the conterminous United States (CONUS). Litter and soil variables were measured on permanent sample plots (n = 3303) from the National Forest Inventory (NFI) within the United States from 2000 to 2011. These data were used with vegetation phenology data estimated from LANDSAT imagery (30 m) and raster data describing environmental variables for the entire CONUS to predict litter and soil C stocks. The total estimated litter C stock was 2.07 ± 0.97 Pg with an average density of 10.45 ± 2.38 Mg ha⁻¹, and the soil C stock at 0–20 cm depth was 14.68 ± 3.50 Pg with an average density of 62.68 ± 8.98 Mg ha⁻¹. This study extends NFI data from points to pixels providing spatially explicit and continuous predictions of litter and soil C stocks on forest land in the CONUS. The approaches described illustrate the utility of harmonizing field measurements with remotely sensed data to facilitate modeling and prediction across spatial scales in support of inventory, monitoring, and reporting activities, particularly in countries with ready access to remotely sensed data but with limited observations of litter and soil variables.
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17314. 题目: Source apportionment of the oxidative potential of fine ambient particulate matter (PM_2.5) in Athens, Greece
文章编号: N18111407
期刊: Science of The Total Environment
作者: Sina Taghvaee, Mohammad H. Sowlat, Evangelia Diapouli, Manousos Ioannis Manousakas, Vasiliki Vasilatou, Kostas Eleftheriadis, Constantinos Sioutas
更新时间: 2018-11-14
摘要: The main objective of this study was chemical characterization and source apportionment of the oxidative potential of ambient PM_2.5 samples collected in an urban background area in Athens, Greece. Ambient PM_2.5 samples were collected during the summer (June–September) of 2017 and winter (February–March) of 2018 at a residential, urban background site in the outlying neighborhood of the Demokritos National Laboratory in Athens, Greece. The collected PM samples were analyzed for their chemical constituents including metals and trace elements, water-soluble organic carbon (WSOC), elemental and organic carbon (EC/OC), and marker of biomass burning (i.e., levoglucosan). In addition, the DCFH in vitro assay was performed to determine the oxidative potential of the PM_2.5 samples. We performed a series of statistical analyses, including Spearman rank-order correlation analysis, principal component analysis (PCA), and multi linear regression (MLR) to determine the most significant species (as source tracers) contributing to the oxidative potential of PM_2.5. Our findings revealed that the intrinsic (per PM mass) and extrinsic (per m³ of air volume) oxidative potentials of the collected ambient PM_2.5 samples were significantly higher than those measured in many urban areas around the world. The results of the MLR analyses indicated that the major pollution sources contributing to the oxidative potential of ambient PM_2.5 were vehicular emissions (characterized by EC) (44%), followed by secondary organic aerosol (SOA) formation (characterized by WSOC) (16%), and biomass burning (characterized by levoglucosan) (9%). The oxidative potential of the collected ambient PM_2.5 samples was also higher in summer compared to the winter, mainly due to higher concentrations of EC and WSOC during this season. Results from this study corroborate the impact of traffic and SOA on the oxidative potential of ambient PM_2.5 in greater Athens area, and can be helpful in adopting appropriate public health policies regarding detrimental outcomes of exposure to PM_2.5.
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17315. 题目: Soil microbial community composition closely associates with specific enzyme activities and soil carbon chemistry in a long-term nitrogen fertilized grassland
文章编号: N18111406
期刊: Science of The Total Environment
作者: Yue Li, Cheng Nie, Yinghui Liu, Wei Du, Pei He
更新时间: 2018-11-14
摘要: Due to the profound impact of nitrogen (N) input on soil systems, linking the activity and composition of soil microbial communities to soil organic carbon (SOC) is crucial to reveal the microbial-driven mechanisms underlying SOC decomposition by nitrogen fertilization. A long-term nitrogen fertilization experiment with 6 urea fertilizer gradients (0, 2, 4, 8, 16, and 32 g N m⁻² yr⁻¹) was conducted on a temperate grassland. The soil basic characteristics, microbial community DNA sequences, five soil enzymes including C, N, and phosphorus cycling, and soil C fractions were measured after 14 years of N addition. N fertilization significantly modified both the bacterial and fungal community composition, with larger variations at higher N levels. N fertilization increased the proportion of copiotrophic bacteria and saprotrophic fungi. Specific enzyme activities standardized by microbial biomass carbon among N fertilizing gradients demonstrated that the potential of labile C acquisition was stable, but the potential of N and P acquisition and recalcitrant C degradation were increased. Recalcitrant soil C fractions including alkyl C and aromatic C significantly differed among N levels, despite the stable SOC concentration. The variations of bacterial phyla and fungal trophic guilds were both associated with specific enzyme activities; meanwhile, fungal phyla were more related to soil C fractions, as the Basidiomycota abundance echoed the proportion of aromatic C at 4–16 g N m⁻² yr⁻¹. In conclusion, this study indicates that the changes in microbial community composition by N fertilization can have far-reaching impacts on SOC turnover and nutrient acquisition.
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17316. 题目: The Natural Activation Ability of Subsurface Media to Promote In-Situ Chemical Oxidation of 1,4-Dioxane
文章编号: N18111405
期刊: Water Research
作者: Ni Yan, Hua Zhong, Mark L. Brusseau
更新时间: 2018-11-14
摘要: The ability of soils and sediments to promote in-situ activation of persulfate and persulfate combined with hydrogen peroxide was investigated for treatment of 1,4-dioxane (dioxane). Experiments were conducted with both batch-reactor and column systems to examine reaction rates and activation mechanisms. Four soils and aquifer sediments were used. ICP-MS and XRD analyses were used to characterize geochemical properties of the solutions and sediments, while EPR spectroscopy was used to characterize radical formation. For the batch experiments, degradation of dioxane was significantly greater in the presence of each of the four subsurface geomedia compared to the controls with no geomedia. This indicates that all four geomedia induced oxidant activation, thereby enhancing dioxane degradation. Dioxane degradation was significantly enhanced by the addition of peroxide to the persulfate solution. It is hypothesized that iron associated with the geomedia is primarily responsible for activation, and that the degree of degradation enhancement relates in part to dissolved-phase iron content. EPR results indicate that manganese oxides and soil organic matter may also have contributed to some degree to persulfate activation, and that manganese oxides enhanced activation of peroxide under the study conditions. Approximately 8% of dioxane was degraded in the miscible-displacement experiments, consistent with the short residence time compared to dioxane’s half-life. The pseudo first-order rate coefficients obtained from the batch and column experiments were similar. The results of this study indicate that subsurface geomedia can induce activation of persulfate and peroxide to enhance in-situ chemical oxidation applications.
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17317. 题目: A new Tier 3 method to calculate methane emission inventory for ruminants
文章编号: N18111404
期刊: Journal of Environmental Management
作者: M. Eugène, D. Sauvant, P. Nozière, D. Viallard, K. Oueslati, M. Lherm, E. Mathias, M. Doreau
更新时间: 2018-11-14
摘要: Livestock is the main source of methane (CH₄) emissions. It is important to accurately determine emissions from ruminants that meet standardized international guidelines for national greenhouse gas inventories. A new method to improve the accuracy of CH₄ emissions that complies with IPCC rules for a Tier 3 method is described and evaluated. This method, developed by INRA (French Institute for Agricultural Research), was applied to the French inventory of CH₄ emissions by ruminants and compared with the IPCC Tier 2 method. For enteric CH₄, depending on the animal category, the INRA CH₄ emission estimates lay between 88% and 114% of IPCC's. The INRA/IPCC ratio for enteric emission was close to unity and did not differ between methods (P = 0.43) for adult cows (i.e. most cattle). In France, feedlot manure is stored in aerobic conditions, and so the INRA/IPCC fit for manure emission was poorer (P < 0.05). The INRA/IPCC fit for enteric CH₄ was very close between methods to that for total CH₄ (P = 0.39), enteric CH₄ representing 93% of total emissions. The main improvement is the use of a robust equation (from numerous data and diets), based on digestible organic matter intake (DOMI) corrected for the digestive interactions, to predict CH₄ consistently from enteric and manure sources. It was developed for the French livestock inventory but is customizable for other countries. This new improved CH₄ estimation method, based on equations from a large literature database, complies with IPCC rules for a Tier 3 method.

17318. 题目: Biogeochemical markers across a pollution gradient in a Patagonian estuary: A multidimensional approach of fatty acids and stable isotopes
文章编号: N18111403
期刊: Marine Pollution Bulletin
作者: G.A. Kopprio, M.S. Dutto, J.E. Garzón Cardona, A. Gärdes, R.J. Lara, M. Graeve
更新时间: 2018-11-14
摘要: A combined approach merging stable isotopes and fatty acids was applied to study anthropogenic pollution in the Río Negro estuary. Fatty acid markers of vegetal detritus indicated considerable allochthonous inputs at freshwater sites. Correlative evidence of diatom fatty acids, δ¹³C, chlorophyll and particulate organic matter suggested the importance of diatoms for the autochthonous organic matter production at the river mouth. Low δ¹⁵N values (~0‰) and high fatty acid 18:1(n-7) concentrations in the suspended particulate matter, in combination with the peaks of coliforms and ammonium, indicated a strong impact of untreated sewage discharge. The ¹⁵N depletion was related to oxygen-limited ammonification processes and incorporation of ¹⁵N depleted ammonium to microorganisms. This work demonstrates that the combined use of lipid and isotopic markers can greatly increase our understanding of biogeochemical factors and pollutants influencing estuaries, and our findings highlight the urgent need for water management actions to reduce eutrophication.
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17319. 题目: Concentrations and loads of DOC, phenols and aldehydes in a proglacial arctic river in relation to hydro-meteorological conditions. A case study from the southern margin of the Bellsund Fjord – SW Spitsbergen
文章编号: N18111402
期刊: CATENA
作者: Sara Lehmann-Konera, Waldemar Kociuba, Stanisław Chmiel, Łukasz Franczak, Żaneta Polkowska
更新时间: 2018-11-14
摘要: Climate warming accelerates the melting and thawing of cryosphere components. Therefore, it favours the release of contaminants stored in High-Arctic glaciers for many years. The rate of land-based glacier retreat is of particular importance for the hydrological regime of glacial rivers, but also for the chemical composition of their waters. In this study, we examined 84 surface water samples collected during a period of 42 days (melt season 2012) from the Scott River of glacial-hydrological regime (NW Wedel-Jarlsberg Land). The studies of Scott River hydro-meteorological conditions provided indication on the relation between mean air temperatures (T) and mean daily discharge (Q) (r = 0.67). Moreover, they confirmed the role of short-term meteorological events (increasing of air temperature and heavy precipitation) on the acceleration of glacier melt. In this context, the study also demonstrated incidents of the release of a more concentrated pulse of chemical compounds delivered by the Scottbreen valley glacier. The analysis covered fluctuations of physicochemical parameters, and presence of selected organic pollutants (∑phenols, formaldehyde (HCHO)). Based on the correlation matrix analysis, it was found that fluctuations of physicochemical indices (pH, specific electrolytic conductivity (SEC) and dissolved organic carbon (DOC)) were related to changes in T and Q. Principal components analysis (PCA)permitted us to distinguish two principal components (hydro-meteorological and biogeochemical conditions) responsible for 71.1% of the total hydrochemical variation. In terms of the first principal component, it was found that there was a relationship with the intensified ablation of glacier ice and with the second one, the influence of geological and biological conditions of the environment on the chemistry of the river. The combination of these factors directly shaped the hydrochemistry of the proglacial river during the melt season of 2012. The results of organic compound loads, which are presented in this paper provide unique information about the transport of contaminants such as: (DOC) (9.41–579 mgC s⁻¹), ∑phenols (19.7–534 mg s⁻¹), HCHO (34.0–82.3 mg s⁻¹)) in the Scott River. It is worth noting that the differentiation of concentration and mean daily loads of DOC, between the gorge (96.0 mgC s⁻¹) and mouth (99.6 mgC s⁻¹) sections of the river, were related with the activity of a herring gull (Larus argentatus) colony at the river mouth.

17320. 题目: Combination of fractional order derivative and memory-based learning algorithm to improve the estimation accuracy of soil organic matter by visible and near-infrared spectroscopy
文章编号: N18111401
期刊: CATENA
作者: Yongsheng Hong, Songchao Chen, Yaolin Liu, Yong Zhang, Lei Yu, Yiyun Chen, Yanfang Liu, Hang Cheng, Yi Liu
更新时间: 2018-11-14
摘要: Visible and near-infrared (Vis–NIR) spectroscopy is used to estimate soil organic matter (SOM). Spectral preprocessing techniques and multivariate modeling methods play important roles in the quantitative analysis of SOM. First and second derivatives (i.e., the conventional integer order derivatives) are commonly used spectral derivatives, which, however, may ignore some detailed spectral information regarding SOM. Here, we presented a fractional order derivative (FOD) method to preprocess the reflectance spectra. Robust modeling methods are still required for accurate estimation of SOM. Local modeling technique (memory-based learning, MBL) was introduced to compare with two global modeling approaches, namely, partial least square (PLS) and random forest (RF). A total of 535 topsoil samples were gathered from Hubei Province, Central China, with their reflectance spectra and SOM contents measured in the laboratory. FOD was allowed to vary from 0 to 2 with an increment of 0.25 at each step. Coefficient of determination (R²) and ratio of the performance to deviation (RPD) were employed as performance statistics during validation. Results showed that with the increase of derivative order, the baseline drifts and overlapping peaks were gradually removed but the spectral strength decreased concurrently. Higher derivative order reflectance (i.e., 1.5-order, 1.75-order, and 2-order reflectance) were more susceptible to spectral noise interferences. The correlation coefficient of SOM with FOD processed spectra at some specific wavelengths was larger than that with the original reflectance. MBL performed better than PLS and RF, regardless of FOD transformation. Calibration with 0.25-order reflectance and MBL provided the most accurate estimation of SOM, with an RPD of 2.23. Our results confirm the effectiveness of FOD and local modeling (MBL) in the development of Vis–NIR models for SOM estimation.
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