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26341. 题目: Investigating the sources and structure of chromophoric dissolved organic matter (CDOM) in the North Pacific Ocean (NPO) utilizing optical spectroscopy combined with solid phase extraction and borohydride reduction
文章编号: N180625E8
期刊: Marine Chemistry
作者: Carmen M. Cartisano, Rossana Del Vecchio, Marla R. Bianca, Neil V. Blough
更新时间: 2018-06-25
摘要: Prior optical measurements of waters in the Equatorial Atlantic Ocean (EAO) provided evidence of a major terrestrial “humic-like” component of the CDOM that absorbed in the ultraviolet (UV) and visible and emitted across the visible, along with a marine component that primarily absorbed and emitted in the UV. Here we extend these measurements to the North Pacific Ocean (NPO) at Station Aloha (22o 45′ N, 158o 00′ W). Detailed optical measurements of both the natural waters (CDOM) and C18 organic matter extracts of these waters (C18-OM) were acquired before and after sodium borohydride (NaBH4) reduction of samples obtained throughout the water column. Optical properties of the “humic-like” component were relatively uniform with depth below ~600 m [aCDOM(350) ~ 0.08 (m 1), a*CDOM (350) ~ 0.2 (m 1 mg 1C L), SUVA254 ~ 0.55 (m 1 mg 1C L), E2:E3 ~ 10, S300–700 ~ 0.02 (nm 1), S350–400 ~ 0.012 (nm 1), SR ~1.7, F(350/450) ~ 0.009 (QSE), and 360 ~ 0.026], but were significantly different in surface waters, likely due to photobleaching and biological activity [aCDOM(350) ~ 0.026 (m 1), a*CDOM (350) ~ 0.027 (m 1 mg 1C L), SUVA254 ~ 0.36 (m 1 mg 1C L), E2:E3 ~ 45, S300–700 ~ 0.03 (nm 1), S350–400 ~ 0.003 (nm 1), SR ~6.8, F(350/450) ~ 0.003 (QSE), and 350 ~ 0.024]. Optical properties of the short-wavelength components (UV bands) were more variable with depth. Response to solid phase extraction was also relatively uniform with depth, with preferential extraction of the long-wavelength absorbing/emitting “humic-like” component (~30–50% extraction efficiency at λ <300 nm and ~50–80% at λ >400 nm) and virtually no extraction of the the UV absorbing/emitting bands. Response to NaBH4 reduction was also similar down the water column with preferential loss of absorption in the visible region, and enhanced, blue-shifted fluorescence emission. As in the EAO the ‘humic-like” component exhibited very similar, although not identical, optical and chemical properties to those observed for terrestrially-dominated estuarine and coastal environments, providing evidence that this component originates from a terrestrial source. Although this component dominated the absorption, marine contributions (i.e. UV bands) similar to those observed in the EAO were also observed. However, these components were found to absorb and emit primarily in the UV and were not efficiently extracted by the C18 columns, clearly showing that they are structurally distinct from the “humic-like” component.

26342. 题目: Major differences in dissolved organic matter characteristics and bacterial processing over an extensive brackish water gradient, the Baltic Sea
文章编号: N180625E7
期刊: Marine Chemistry
作者: Owen F. Rowe, Julie Dinasquet, Joanna Paczkowska, Daniela Figueroa, Lasse Riemann, Agneta Andersson
更新时间: 2018-06-25
摘要: Dissolved organic matter (DOM) in marine waters is a complex mixture of compounds and elements that contribute substantially to the global carbon cycle. The large reservoir of dissolved organic carbon (DOC) represents a vital resource for heterotrophic bacteria. Bacteria can utilise, produce, recycle and transform components of the DOM pool, and the physicochemical characteristics of this pool can directly influence bacterial activity; with consequences for nutrient cycling and primary productivity. In the present study we explored bacterial transformation of naturally occurring DOM across an extensive brackish water gradient in the Baltic Sea. Highest DOC utilisation (indicated by decreased DOC concentration) was recorded in the more saline southerly region where waters are characterised by more autochthonous DOM. These sites expressed the lowest bacterial growth efficiency (BGE), whereas in northerly regions, characterised by higher terrestrial and allochthonous DOM, the DOC utilisation was low and BGE was highest. Bacterial processing of the DOM pool in the south resulted in larger molecular weight compounds and compounds associated with secondary terrestrial humic matter being degraded, and a processed DOM pool that was more aromatic in nature and contributed more strongly to water colour; while the opposite was true in the north. Nutrient concentration and stoichiometry and DOM characteristics affected bacterial activity, including metabolic status (BGE), which influenced DOM transformations. Our study highlights dramatic differences in DOM characteristics and microbial carbon cycling in sub-basins of the Baltic Sea. These findings are critical for our understanding of carbon and nutrient biogeochemistry, particularly in light of climate change scenarios.

26343. 题目: Photoreactivities of two distinct dissolved organic matter pools in groundwater of a subarctic island
文章编号: N180625E6
期刊: Marine Chemistry
作者: Liming Qi, Huixiang Xie, Jean-Pierre Gagné, Gwena?lle Chaillou, Philippe Massicotte, Gui-Peng Yang
更新时间: 2018-06-25
摘要: Groundwater is a potentially significant source of dissolved organic matter (DOM) to coastal oceans where it is subject to photochemical transformation and thus possibly influences major marine biogeochemical processes. Furthermore, groundwater DOM usually receives little prior light exposure, making it suitable for probing the photoreactivity of source organic materials. In this study we collected two DOM pools in beach and inland groundwater of the les-de-la-Madeleine in the Gulf of St. Lawrence, characterized them with absorbance and fluorescence spectroscopy, and compared their photoreactivities. Beach groundwater (BGW) primarily comprised old, highly colored terrestrial DOM having high molecular weight (MW), strong humification, and low protein contents, whereas inland groundwater (IGW) largely contained fresh, less colored microbial-derived DOM with low molecular weight (MW), weaker humification, and higher protein contents. For both BGW and IGW, exposure to solar-simulated radiation led to increases in the E2/E3 quotient, biological index (BIX), and ammonium (NH4 +) and decreases in absorbance, specific absorption coefficient at 254 nm (SUVα254), fluorescence index (FI), humification index (HIX), MW, and dissolved organic carbon (DOC). The irradiation also reduced the intensities of humic-like fluorescence peaks and PARAFAC-modeled humic components. On a fractional-absorption-loss basis, the photochemically induced fractional changes in BGW were comparable to those in IGB for SUVα254 and E2/E3, considerably larger for MW, BIX, and DOC, and substantially smaller for FI and HIX. On an absorbed-photon basis, the efficiencies of absorbance photobleaching and DOC photomineralization for DOM in BGW were 8.3 times and 2.0 times those of the respective photoprocesses for DOM in IGW, while the efficiency of photoammonification for DOM in BGW was 41% of that for DOM in IGW. Results from this study, in combination with those reported previously for surface waters, lead to a tentative paradigm: terrigenous DOM is more prone to absorbance photobleaching but less prone to photoammonification than microbial-derived DOM while the two DOM pools are comparably reactive with respect to DOC photomineralization.

26344. 题目: Size-fractionated distributions of suspended particle concentration and major phase composition from the U.S. GEOTRACES Eastern Pacific Zonal Transect (GP16)
文章编号: N180625E5
期刊: Marine Chemistry
作者: Phoebe J. Lam, Jong-Mi Lee, Maija I. Heller, Sanjin Mehic, Yang Xiang, Nicholas R. Bates
更新时间: 2018-06-25
摘要: Marine particles play key roles in the cycling of most elements in the ocean. Here we present full water column sections of size-fractionated (1–51μm; >51μm) concentrations of suspended particulate matter (SPM) and major particle phase composition, including particulate organic matter (POM), calcium carbonate (CaCO3), opal, lithogenic particles, and iron and manganese (oxyhydr)oxides, as well as the Redfield (C:N:P) stoichiometry of particles, from the U.S. GEOTRACES GP16 Eastern Pacific Zonal Transect (EPZT). The GP16 cruise sampled the oxygen deficient waters of the productive eastern upwelling Peru margin westward to Tahiti through the East Pacific Rise (EPR) hydrothermal plume around 12°S in October–December 2013. In this region of relatively low mineral dust deposition, the sum of POM and CaCO3 concentrations accounted for >80% of small size fraction (SSF) SPM for most of the section. Some exceptions to this include the southern EPR hydrothermal plume, where iron oxyhydroxides accounted for almost 60% of SSF SPM, and the coastal upwelling zone, where opal and lithogenic particles accounted for ~50% of SSF SPM. We discuss possible mechanisms to explain a large sediment resuspension feature on the deep Peru continental slope. Large size fraction (LSF) particles generally had relatively higher contributions of opal and lower contributions of POM compared to SSF particles, reflecting an unusually high size partitioning of opal to the LSF. Distributions of CaCO3 and other phases were more strongly controlled by particle dynamics than by dissolution. Our particle phase data are consistent with a conceptual model where particle production, aggregation, and disaggregation processes dominate in the euphotic, 100–300m, and 300–500m depth zones, respectively. Our direct measurements of particle composition showed 1) euphotic zone C vs P relationships (SSF: 48±13; LSF: 65±14) that were significantly lower than canonical Redfield values (~106), but that were consistent with previously published large scale inverse and box model estimates of exported C:P for this region, and 2) PIC:POC ratios (LSF: 0.088) that were remarkably similar to estimated rain ratios from a biogeochemical-transport box model of alkalinity and nitrate in the low latitude Pacific.

26345. 题目: Bias in carbon concentration and δ13C measurements of organic matter due to cleaning treatments with organic solvents
文章编号: N180625E4
期刊: Chemical Geology
作者: ?lodie Muller, Christophe Thomazo, Eva E. Stüeken, Christian Hallmann, Arne Leider, Carine Chaduteau, Roger Buick, Franck Baton, Pascal Philippot, Magali Ader
更新时间: 2018-06-25
摘要: Interpreting the organic carbon content (TOC) and stable carbon isotopic composition (δ13C) of organic matter in the sedimentary rock record depends on our capability to accurately measure them, while excluding sources of contamination. This however becomes increasingly problematic as we analyze samples with ever-lower organic carbon content. Accordingly, organic solvents are sometimes used to remove contaminating traces of modern organic matter from ancient rock samples. However, especially for very low TOC samples, traces of solvents or their impurities remaining in the sample may contribute a significant organic contamination that can impact the bulk measurements of both TOC and δ13C values. This study, including three independent investigations performed in different laboratories, is the first detailed examination of the effect of cleaning treatments on the reliability of TOC and δ13C values in a range of natural rock samples and synthetic materials with low TOC content from below detection limit to 3330 ppm. We investigated the four most common organic solvents used to remove modern organic matter: dichloromethane (DCM), n-hexane, methanol and ethanol, and evaluated the effect of grain size and mineralogy. We find that (i) cleaning treatments with methanol, n-hexane and dichloromethane contaminate rock samples when used directly on sample powder, regardless of the grain size; (ii) this pollution buffers the natural variability and homogenizes the δ13C values of samples around the isotopic composition of the solvent, i.e. between 27 and 29‰; (iii) the extent of contamination depends on the solvent used, DCM being the most contaminating (up to 6000 ppm) and ethanol the only solvent that does not seem to contaminate rock samples above our detection limit; (iv) sample mineralogy also exerts an influence on the extent of contamination, clay minerals being more prone to adsorb contaminants. We conclude that the response of carbon concentrations and the stable carbon isotopic composition of organic matter in geological samples to cleaning treatments is neither negligible nor systematic when investigating samples with low carbon content.

26346. 题目: Degassing of organic carbon during regional metamorphism of pelites, Wepawaug Schist, Connecticut, USA
文章编号: N180625E3
期刊: Chemical Geology
作者: Shuang Zhang, Jay J. Ague, Alberto Vitale Brovarone
更新时间: 2018-06-25
摘要: A comprehensive understanding of the degassing systematics of organic carbon (OC) during regional metamorphism is necessary to evaluate the role that metamorphism plays in the global carbon cycle. In this study, weight percentages and δ13C values of OC were measured in 70 samples of metapelites from the Wepawaug Schist, Connecticut, where classic Barrovian metamorphism occurred and graphitic OC is widespread. Relative to low-grade chlorite + biotite zone rocks, our mass balance analysis shows that OC in the metapelites underwent progressive loss from 14% ( 0.06 g OC per 100 g rock) in the garnet zone, through 21% ( 0.09 g/100 g) in the staurolite zone, to 26% ( 0.11 g/100 g) in the kyanite zone. The average δ13C values in different metamorphic zones (ranging from 14.74‰ to 16.24‰) are all much higher than normal organic material in marine sediments, and increase slightly from the chlorite + biotite zone to the garnet zone and decrease slightly at higher metamorphic grades. Organic carbon degassing in the form of CH4 during the late stage of diagenesis or in the earliest stages of metamorphism could produce this significant 13C enrichment. Under the assumption that the 13C enrichment is caused by graphite degassing during the lowest-grade metamorphism (chlorite zone or lower), the degassing profile of OC during the regional metamorphism is reconstructed by combining the δ13C and OC mass change data. The computed results indicate that graphitic OC in the Wepawaug Schist probably underwent considerable loss at lowest-grade metamorphic conditions, ranging from ~ 40% to ~ 90% (or from 0.23 g OC per 100 g rock to 2.8 g OC per 100 g rock), and remained relatively inert at higher grades. Based on the mass balance analysis, δ13C systematics, and exploratory modeling results, this study argues that the lowest-grade or pre-metamorphic stages would be the more efficient OC liberators, and that the degassing potential of OC in the major stages of Barrovian metamorphism appears to be much more restricted. Additional independent studies are required to decipher the early degassing of OC after the deposition of organic matter, which could in turn help better constrain the degassing of OC during regional metamorphism.

26347. 题目: Dwindling vanadium in seawater during the early Cambrian, South China
文章编号: N180625E2
期刊: Chemical Geology
作者: Tao Han, Haifeng Fan, Hanjie Wen
更新时间: 2018-06-25
摘要: Elemental vanadium (V), an essentially redox-sensitive metal in seawater, has had a significant impact on the understanding of the evolution of the atmosphere-ocean system throughout the history of the Earth. In fact, the geochemical cycle of V in early Cambrian seawater may have had an influence on the Chengjiang Biota in South China; however, it has not yet been well established. Given the authigenic vanadium accumulation is sensitive to the redox conditions of seawater, here, to constrain the geochemical cycle of V in seawater during the early Cambrian, the Mo, U and total organic carbon (TOC) distributions with high-resolution samples from both the outer shelf and slope facies (e.g., the Duoding and Longbizui sections), are applied to evaluate the redox conditions of ambient seawater. The Mo-U relationships indicate that the redox conditions of the mid-depth seawater evolved in a systematic way in South China, transitioning from an Fe-Mn reduction zone to anoxic/intermittently euxinic states and then to oxic conditions during the early Cambrian. As a consequence, the authigenic V enrichment, constrained by the marine redox conditions, was mainly controlled by the Fe-Mn particulate shuttle and the reduction and adsorption of organic matter in anoxic/euxinic conditions. However, the decoupling among V, Mo, U and TOC under anoxic/euxinic conditions suggests a dwindling vanadium concentration in the early Cambrian seawater of South China. The scavenging efficiency of V from seawater is much higher than those of Mo and U under anoxic/euxinic conditions. Ultimately, these trace elements (e.g., Mo, U, and especially V) in seawater could effectively be regulated and adjusted to a reasonable level under the widespread anoxic/euxinic conditions. The drawdown of trace elements in seawater might provide an early-stage preparation of the marine environment for the subsequent Chengjiang Biota.

26348. 题目: Fate of particulate copper and zinc isotopes at the Solim?es-Negro river confluence, Amazon Basin, Brazil
文章编号: N180625E1
期刊: Chemical Geology
作者: Damien Guinoiseau, Julien Bouchez, Alexandre Gélabert, Pascale Louvat, Patricia Moreira-Turcq, Naziano Filizola, Marc F. Benedetti
更新时间: 2018-06-25
摘要: The behaviour and fate of copper (Cu) and zinc (Zn) at river confluences is poorly understood, although chemical and physical processes during mixing of compositionally different tributaries might condition metal availability and fluxes to the ocean. To identify and quantify the effect of such processes in river mixing zones, particulate Cu and Zn isotope signatures (δ65CuSPM and δ66ZnSPM) were measured along cross sections and vertical profiles at the largest river confluence in the world, the “Encontro das Aguas” mixing zone of the Amazon River, where the organic-rich Negro River meets the sediment-rich Solim es River. The Negro River suspended sediments, with highly variable Cu and Zn concentrations as well as δ65CuSPM and δ66ZnSPM, are mostly influenced by organic matter and by the lateritic cover of the watershed. The Solim es River suspended sediments, more homogeneous in Cu and Zn concentration and isotope composition across the river section, reflect the signature of weathered silicate-rich sediments derived from the Andes. The Solim es River supplies the majority of the suspended Cu and Zn to the Amazon River, and despite important flux losses across the confluence ( 35% for Cu and 27% for Zn), δ65CuSPM and δ66ZnSPM show a conservative behaviour during the mixing. In the dissolved load, Cu concentrations and δ65Cudiss, mostly supplied by the Solim es River, behave conservatively whereas Zn, derived mainly from the Negro River, suffers an important loss ( 58%) that can be attributed to Zn adsorption onto the suspended sediments from the Solim es River. This transfer does not induce a significant δ66ZnSPM shift in the Amazon River suspended sediments. Therefore, Cu and Zn isotope ratios in the suspended sediments behave conservatively through this confluence, which mixes two very chemically-contrasted rivers. Our findings thus suggest that the riverine isotopic information on the sources of particulate Cu and Zn is preserved during tributary mixing.

26349. 题目: Links between seawater paleoredox and the formation of sediment-hosted massive sulphide (SHMS) deposits — Fe speciation and Mo isotope constraints from Late Devonian mudstones
文章编号: N180625E0
期刊: Chemical Geology
作者: Joseph M. Magnall, Sarah A. Gleeson, Simon W. Poulton, Gwyneth W. Gordon, Suzanne Paradis
更新时间: 2018-06-25
摘要: Many models of sediment hosted massive sulphide (SHMS) deposit formation invoke basin restriction events that resulted in long-term stagnation and anoxia, in which sulphidic (euxinic) conditions ultimately prevailed. Euxinic conditions are then thought to provide a chemical trap for hydrothermally exhaled base metals. Here, we present Fe speciation and Mo isotope data for organic-rich mudstones from two drill-holes intersecting Upper Devonian strata, deposited along the passive margin of ancestral North America. One drill-hole intersects a 35 m thick sequence of SHMS mineralisation, while the other intersects correlative, un-mineralised strata. All samples have high FeHR/FeT values (>0.38), indicating water-column anoxia. For the majority of samples in the un-mineralised drill-hole, the levels of pyritisation fall below the threshold typically used to define euxinic conditions (FePY/FeHR ≤ 0.70). In contrast, higher levels of pyritisation in the mineralised drill-hole (median FePY/FeHR = 0.86) likely developed via diagenetic pyrite enrichment. Whereas Pb and Zn are negatively correlated with Mo, Mo-U co-variation is consistent with Fe (oxyhydr)oxide particulate shuttling in the water-column. In addition, a weak correlation between TOC/P and Mo provides further evidence that Mo was sourced via authigenic, rather than hydrothermal, processes. The δ98Mo values (+0.66 to +1.02‰) are uniform between both drill-holes, and substantially lower than constraints for Late Devonian seawater (+1.5 to +2.0‰), consistent with Mo adsorption to Fe (oxyhydr)oxides. Collectively, the data provide evidence that local seawater was dominantly ferruginous (anoxic, non-sulphidic) at Macmillan Pass. Regional variability in the extent of ferruginous (low TOC/P) and euxinic (high TOC/P) conditions likely contributed to a balance between P regeneration and P enrichment that maintained nutrient availability and productivity in the Selwyn Basin during the Late Devonian. We argue that high primary productivity and enhanced organic carbon burial are key variables for promoting sulphate reduction in the sub-surface. Moreover, how such conditions are maintained over long periods of basin evolution is more important for producing effective metal traps in SHMS systems, rather than a specific, localised redox condition of seawater (i.e. euxinia).

26350. 题目: A combination of ammonia stripping and low temperature thermal pre-treatment improves anaerobic post-digestion of the supernatant from organic fraction of municipal solid waste treatment
文章编号: N180625D9
期刊: Waste Management
作者: Chiara Pedizzi, Juan M. Lema, Marta Carballa
更新时间: 2018-06-25
摘要: Municipal Solid Waste is mostly composed of organic material which is often treated in anaerobic reactors in waste treatment plants. In most cases, the obtained digestate undergoes a solid/liquid separation step, producing a liquid fraction (known as anaerobic supernatant) rich in ammonium nitrogen that has to be further treated in order to meet discharge standards. The objective of the present work was to evaluate the feasibility of anaerobic post-digestion (37 °C) of a supernatant rich in carbon and nitrogen from a municipal waste treatment plant. In order to increase the efficiency of the process, a combined pre-treatment consisting of a low-temperature thermal process (75 °C) and ammonia stripping (1.3 Lair Lsupernatant 1 min 1) was applied. The effects of pre-treatment contact time (4 and 8 h) and the hydraulic retention time (HRT) in the anaerobic reactor (20–40 d) were studied. Supernatant pre-treatment with 8-h contact time caused 13% organic matter solubilisation, thus improving methanisation by 18% when the HRT was 40 d. At the same time, ammonia stripping allowed to maintain ammonia concentration in the digester below inhibitory values (less than 100 mg N-NH3 L 1) enabling therefore high methanogenic activity (>0.23 g COD g 1 VS d 1). The final effluent characteristics (low total ammonia nitrogen and aerobically biodegradable organic matter levels) would permit implementing subsequent less energy intensive and more environmental-friendly technologies (such as partial nitritation/anammox) to comply with discharge limits.

26351. 题目: Characterization of dissolved organic matter from biogas residue composting using spectroscopic techniques
文章编号: N180625D8
期刊: Waste Management
作者: Xujing Guo, Chongwei Li, Qili Zhu, Tao Huang, Yu Cai, Nanxi Li, Jianying Liu, Xiandong Tan
更新时间: 2018-06-25
摘要: Dissolved organic matter (DOM) extracted from composting of biogas residue was characterized using spectroscopic techniques. Spectral parameters, specific UV absorbance at 254 (SUVA254), ratios of spectral slopes (SR), and humification index (HIX) were used to assess the structural characteristics of the DOM. During composting, the UV absorbance at 254 increased as the relatively resistant aromatic fraction was released and the DOM molecular weight increased with the degree of humification. Fluorescence excitation-emission matrix (EEM) spectra with regional integration analysis (FRI) and accumulative fluorescence emission (AFE) combined with second derivative spectroscopy were used to assess the evolution of the DOM and evaluate the production of resistant humic-like substances during composting. Second derivative spectroscopy showed that microbial-derived humic-like substance A2 was easily degraded during composting. Two-dimensional correlation spectroscopy (2D-COS) combined with Fourier-transform infrared (FTIR) spectroscopy determined the preferential change sequence of the functional groups was 2000–2300 (CC or CN) → 1288 cm 1 (amide III) at x1 and 2935 (aliphatic groups) → 1420 (carboxylic groups) → 3100–3400 (hydroxyl groups) → 1660 cm 1 (aromatic CC) at x2, suggesting that functional groups of CC or CN, and amide III can be degraded preferentially, and aromatic CC groups were difficultly degraded. The present study showed spectroscopic techniques are valuable tools for assessing composting of biogas residues.

26352. 题目: Efficiency of landfill leachate treatment in a MBR/UF system combined with NF, with a special focus on phthalates and bisphenol A removal
文章编号: N180625D7
期刊: Waste Management
作者: Sylwia Fudala-Ksiazek, Mattia Pierpaoli, Aneta Luczkiewicz
更新时间: 2018-06-25
摘要: In this study, a pilot-scale membrane bioreactor (MBR) was operated at a municipal solid waste plant (MSWP) to treat a mixture of landfill leachates (LLs) obtained from modern (MP-LLs) and previous (PP-LLs) waste cells. The MBR unit combined anoxic and aerobic zones with external ultra- and nanofiltration (MBR/UF and MBR/UF/NF, respectively). In addition to the removal of macropollutants, special attention was given to phthalates (PAEs) and bisphenol A (BPA). According to the obtained results, the MBR/UF system with acclimated biomass was effective for treating LLs, and the obtained effluent was generally similar in quality to raw municipal wastewater. The MBR biomass showed high potential for BPA and PAEs biodegradation/biotransformation as confirmed by a metagenomic approach. Only a high chloride concentration (1960 mg Cl /L), which was twice the value acceptable by Polish regulations for industrial wastewater entering the municipal wastewater system, justifies the additional usage of the NF unit. Notably, a decreasing amount of biodegradable organic matter in MBR influent is expected with time because of changes in the biochemistry of modern waste cells; therefore, an external carbon source would probably be needed to support denitrification. However, the cooccurrence of an aerobic and anaerobic ammonia-oxidizing community with denitrifying bacteria provides the opportunity for advanced removal of nitrogen and organic carbon.

26353. 题目: Full scale study of Class A biosolids produced by thermal hydrolysis pretreatment and anaerobic digestion
文章编号: N180625D6
期刊: Waste Management
作者: Xuanzhao Wang, Natasha Andrade, Jessica Shekarchi, Sarah J. Fischer, Alba Torrents, Mark Ramirez
更新时间: 2018-06-25
摘要: Biosolids are the solid by-product of wastewater treatment and contain high-organic matter and nutrient content, which can be utilized in food production and gardening. In 2014, this study’s target nutrient recovery facility (NRF) in the Mid-Atlantic region of the U.S. adopted thermal hydrolysis pretreatment (THP) and anaerobic digestion (AD) to upgrade biosolids from Class B (lime-stabilized) to Class A. The pathogen, nutrients, and metals contents were compared with that of Class B biosolids from the same facility throughout a one-year period. Following optimization and equilibrium, stable biosolids were produced that satisfied all Environmental Protection Agency (EPA) Class A biosolids standards. Class A biosolids produced had fecal coliform density consistently below the 1000 MPN/g d.w. limit set by the EPA, at 35.85 ± 81.10 MPN/g d.w. (n = 301). Metal concentrations were greater in Class A than Class B biosolids as a result of biosolids mass reduction, but these levels were substantially lower than regulatory limits. Metal concentrations were (in mg/kg d.w.): As = 6.43 ± 0.400 (n = 141), Cd = 3.39 ± 0.117 (n = 147), Cr = 88.4 ± 2.00 (n = 148), Cu = 401 ± 9.81 (n = 148), Pb = 68.1 ± 2.19 (n = 148), Hg = 1.21 ± 0.116 (n = 148), Mo = 14.9 ± 0.321 (n = 148), Ni = 23.8 ± 0.911 (n = 146), Se = 10.0 ± 0.573 (n = 140), Zn = 778 ± 14.9 (n = 148), K = 850 ± 21.7 (n = 134). In addition, Class A biosolids were rich in total nitrogen (N) and higher in total phosphorus (TP), but low in potassium (K) content. Concentration of K was 850 ± 21.7 mg/kg d.w. (n = 134), TKN was 52,000 ± 13,300 mg/kg d.w. (n = 43), TP was 34,500 ± 6130 mg/kg d.w. (n = 42), and ammonia-N was 7860 ± 1350 mg/kg d.w. (n = 43).

26354. 题目: Particle-scale visualization of the evolution of methanogens and methanotrophs and its correlation with CH4 emissions during manure aerobic composting
文章编号: N180625D5
期刊: Waste Management
作者: Jinyi Ge, Guangqun Huang, Junbao Li, Lujia Han
更新时间: 2018-06-25
摘要: Methane (CH4) emissions are a major environmental concern in composting facilities. Therefore, this study initially visualized the dynamic distribution and quantity of methanogens and methanotrophs in composting particles during manure aerobic composting using fluorescence in situ hybridization–confocal laser scanning microscopy (FISH–CLSM) and quantified their correlation with CH4 emissions. The visualization results showed that methanogens existed inside the particles, while methanotrophs clustered in the outer layer; a facultative anaerobic zone existed in between. The quantification results of integral optical density of methanogens and methanotrophs per unit particle area (U gen and U oxi, respectively) indicated that, in the cooling phase, CH4 generation and oxidation could still be high and could strike a balance if the initial organic matter content of composting materials is high, while both could be extremely low if the content is low. A strong linearity between U gen obtained by FISH–CLSM and methyl-coenzyme M reductase copy number obtained by quantitative polymerase chain reaction analysis (R 2 = 0.88) was observed, which justified the effectiveness of the FISH–CLSM method and demonstrated that macro-scale CH4 emissions were essentially an accumulation of particle-scale CH4 emissions. CH4 emissions were equal to 3.3297 × 107 U gen – 3.1814 × 106 U oxi – 3902.9900 (R 2 = 0.98). Overall, the results showed that methanogens exerted more influence on CH4 emissions than methanotrophs. Combining these results with CH4-generation and -oxidation kinetics may help illustrate CH4-emission mechanisms, improve particle-scale CH4-emission models, and thereby provide theoretical guidance for operation optimization and emission reduction in composting processes.

26355. 题目: Performance of a two-stage anaerobic digestion system treating fruit pulp waste: The impact of substrate shift and operational conditions
文章编号: N180625D4
期刊: Waste Management
作者: Mónica Carvalheira, Joana Cassidy, Jo?o M. Ribeiro, Bruno A. Oliveira, Elisabete B. Freitas, Christophe Roca, Gilda Carvalho, Adrian Oehmen, Maria A.M. Reis
更新时间: 2018-06-25
摘要: Food and beverage industry wastes present high amounts of organic matter, which may cause water quality degradation if not treated. Two-stage anaerobic digestion is a promising and efficient solution for the treatment of this type of wastes whilst producing bioenergy. The composition of fruit pulp waste varies throughout the different harvesting seasons, which may impact the process performance. In this study, a two-stage anaerobic digestion system was operated to assess the effect of substrate shift from peach to apple pulp wastes (obtained from a fruit juice company) on the microbial community activity and performance. During acidogenesis, the sugar conversion was higher than 95% for all operational conditions tested, obtaining a degree of acidification up to 89%. Principal Component Analysis was used to evaluate the relationship between the initial fermentation state of the residues in each operational condition and the obtained effluent. Methanogenic activity resulted in high organic carbon consumption (89%) and high methane productivities, achieving a maximum of 4.33 L C H 4 / L . d for peach waste influent. Overall, the results showed that the microbial community activity was not affected by the substrate shift, converting the sugars into biogas rich in methane (>70% CH4). Microbial analysis showed that the communities present in the acidogenic and methanogenic reactors were highly enriched in bacteria and archaea, respectively. The observed stability of the process, also demonstrated in pilot scale, confirmed the robustness of the process and thus, was suitable for implementation in companies producing seasonally different fruit wastes in a continuous operation.

26356. 题目: Biogeochemical dynamics and bioaccumulation processes in Manila clam: Implications for biodiversity and ecosystem services in the Ria de Aveiro Lagoon
文章编号: N180625D3
期刊: Estuarine, Coastal and Shelf Science
作者: Silvia Breda, Stefania Chiesa, Rosa Freitas, Etelvina Figueira, Francesca Becherini, Lorena Gobbo, Amadeu M.V.M. Soares, Emanuele Argese
更新时间: 2018-06-25
摘要: The present work was carried out in the Ria de Aveiro Lagoon (Portugal) to better understand the dynamics driving the bioaccumulation processes in edible bivalves, namely in the Manila clam Ruditapes philippinarum. For the first time, a holistic approach was applied, collecting data on sediment physico-chemical characteristics and its contamination, geochemical speciation and metal(loid) bioaccumulation in clams, from three exploited areas of the lagoon (Costa Nova, Torreira, lhavo). The Ria de Aveiro Lagoon is part of the Natura 2000 network, has the designation of Special Protection Area (SPA), contains Sites of Community Importance (SCI), it is protected by the EU Birds Directive (79/109/CEE) and includes a natural reserve in its northern part. Specifically concerning the metal(loid) occurrence, the monitoring and the identification of contaminated sites in protected areas are priorities, to improve the biodiversity conservation efforts and to ensure the correct management of natural resources. Results showed that multiple driving forces interacted together to determine site-specific impacts, resulting in different risks at local scale for the transferring of the metal(loid)s to the trophic chain. Hydrodynamics played a major role driving the occurrence of depositional or ablative sites, influencing the granulometric composition of sediments and their contamination; metal(loid) chemical forms were then determinated by multiple factors like pH, redox potential and organic matter content. The geochemical speciation data showed that the lhavo area should be considered the most dangerous in terms of clam consumption, since in case of environmental changes, possible conversion of the elements from the potentially bioavailable forms to the bioavailable ones can occur. Moreover, bioaccumulation processes in Manila clam were observed for Cd, Zn and especially As, the latter representing serious risk for consumer safety throughout clam consumption.

26357. 题目: Effects of Zostera marina rhizosphere and leaf detritus on the concentration and distribution of pore-water sulfide in marine sediments
文章编号: N180625D2
期刊: Estuarine, Coastal and Shelf Science
作者: Alexandra G. Simpson, Laura Tripp, David H. Shull, Sylvia Yang
更新时间: 2018-06-25
摘要: The relationship between seagrasses and pore-water hydrogen sulfide in the sediment is complex due to the opposing effects of the seagrass root system, which can reduce sulfide concentration by promoting its oxidation to sulfate, and the burial of organic matter from the plant itself, which can increase sulfide concentration by stimulating anaerobic sulfate reduction. Here, field samples of pore-water sulfide were collected in areas with and without Zostera marina shoots using Diffusive Gradients in Thin-Films (DGTs) to obtain two-dimensional visualizations of sulfide concentrations within the sediment in relation to location of eelgrass detritus and the rhizosphere. To decouple the effects of leaf detritus and the eelgrass rhizosphere on sulfide, manipulative laboratory studies were conducted over 4 weeks using 10 aquaria with or without eelgrass and different quantities of eelgrass detritus planted at 4 cm and 11 cm depths. Spatial distribution of pore-water sulfide was again measured via DGT. We found high spatial variation in pore-water sulfide concentration depending on the location analyzed relative to the rhizosphere or detritus. In the field study, pore-water sulfide concentration was greater in samples with eelgrass present, and the presence of leaf detritus accounted for higher than average sulfide concentrations in the sediment. In the laboratory experiment, sulfide concentrations localized around the leaf detritus increased with higher mass of added detritus, and sediment within the rhizosphere exhibited reduced sulfide concentrations. These results suggest that on the large scale the presence of eelgrass increases sulfide concentration, but on the smaller scale the pattern varies, with higher concentrations near buried detritus and lower concentrations near root tips.

26358. 题目: Long range transport and carbon and nitrogen dynamics of floating seagrass wracks in Greater Florida Bay
文章编号: N180625D1
期刊: Estuarine, Coastal and Shelf Science
作者: Rachel A. Perry, Jamie M.P. Vaudrey, Heidi M. Dierssen
更新时间: 2018-06-25
摘要: Floating aggregations of seagrass wrack can serve as an ecological “hot spot” contributing to the survival of many species in the form of habitat and food source. Considerable research has been conducted on seagrass wrack that is washed ashore, but here we demonstrate that large amounts of floating wrack produced in Greater Florida Bay can be advected great distances from their source, remain buoyant for weeks, and provide a nutrient subsidy into surrounding waters. Drifters tracking the location of floating Syringodium filiforme wracks revealed that movement of the wrack is strongly correlated to wind speed with total daily movement ranging from 10 to 40 km d 1. In mesocosm experiments, shedding followed an exponential model with highest rates estimated for loose aggregations of S. filiforme ( 0.124 d 1) compared to Thalassia testudinum (-0.047 d 1). Aggregated whorled S. filiforme wrack found offshore had an order of magnitude lower shedding with a rate of 0.013 d 1 suggesting it could remain buoyant for several months. Both wrack and the floating macroalgae Sargassum sp. released considerable amounts of dissolved organic carbon (DOC) and colored dissolved organic material (CDOM) daily into the dark mesocosm treatments. CDOM represented a constant proportion of the DOC exudate with a spectral slope suggestive of humic materials. Sargassum sp. produced twice as much DOC and CDOM compared to seagrass wrack. No net release of dissolved nitrogen was measurable in the treatments during the first 5 to 6 days while vegetation was photosynthetically viable, but particulate organic matter increased in the treatments consistent with the growth of bacterioplankton (C:N 7). Similar to Sargassum sp., seagrass wrack can be advected offshore and serve as a carbon and nitrogen source for organisms in oligotrophic waters.

26359. 题目: Mangrove carbon assessment tool: Model development and sensitivity analysis
文章编号: N180625D0
期刊: Estuarine, Coastal and Shelf Science
作者: Zhaohua Dai, Carl C. Trettin, Steve Frolking, Richard A. Birdsey
更新时间: 2018-06-25
摘要: It is important to have the capability to assess carbon (C) dynamics in mangrove forests and estimate their role in mitigating climate change because of their high carbon density, the threats to their integrity from land-use change and sea-level rise, and functional linkages of the many goods and services. A process-based model for mangroves was developed by integrating new features with existing biogeochemical processes in Forest-DNDC for simulating C sequestration and turnover in mangrove ecosystems. The new model is used to assess (1) the dynamics of C, nitrogen and phosphorous in mangrove ecosystems, including above-and below-ground C in saline wetlands, (2) the impacts of ecological drivers, including climate, soil nitrogen and phosphorous deficit and salt stress, on mangrove production, (3) the production of methane, and aerobic and anaerobic oxidation of methane with sulfate, nitrate and nitrite reductions, (4) the contributions of dissolved inorganic C (DIC), dissolved organic C (DOC), particulate organic C (POC) and burial C (BC) to blue C, and (5) impacts of natural and anthropogenic disturbances on C sequestration in mangrove ecosystems. Model sensitivity analysis showed that C sequestration in mangrove ecosystems was highly sensitive to multiple ecological factors, including climate, soil phosphorus, salinity and sulfate, as well as latitude. The responses of different C components to these factors were distinct. The responses of gross and net primary productivity and aboveground biomass to alterations of mean daily temperature (MDT) were quadratic, or increasing or decreasing non-linearly with an increment or decrement in MDT, but leaf production was linear. Similarly, other mangrove C components, such as BC, DIC, DOC and POC, respond substantially to variations of the ecological drivers. The combined effects of the driving factors are complex due to their intricate interactions. For example, while mangrove productivity is sensitive to available phosphorous, phosphorous cannot mitigate the stress imposed by high salinity. These results highlight the value of a tool to assess C dynamics in mangroves, especially for regional or large mangrove forests.

26360. 题目: River plume and bottom boundary layer – Hotspots for nitrification in a coastal bay?
文章编号: N180625C9
期刊: Estuarine, Coastal and Shelf Science
作者: Ines Bartl, Iris Liskow, Kirstin Schulz, Lars Umlauf, Maren Voss
更新时间: 2018-06-25
摘要: Coastal zones, impacted by major rivers, comprise distinct environments, such as river plumes and bottom boundary layers (BBL). These environments are characterized by high nutrient concentrations and high microbial activities and thus offer favourable conditions for nitrification, a key process in the coastal nitrogen cycle. Because nitrification provides substrates for both primary production and denitrification, elucidation of its magnitude and regulation is crucial for understanding the nitrogen cycle in coastal zones. During three research cruises covering three seasons, the enhancement of nitrification rates and their regulation by environmental variables, including salinity, temperature, oxygen, and inorganic and organic nitrogen were investigated in river plume and BBL of the Vistula Estuary (Bay of Gdansk, Southern Baltic Sea). Nitrification rates were not enhanced in the river plume (39 ± 38 nmol L 1 d 1) compared to coastal surface water (45 ± 18 nmol 1 d 1) but the relationship to salinity and particulate organic nitrogen changed, suggesting different regulatory mechanisms along the salinity gradient. Nitrification rates in the BBL covered a range from 1 to 227 nmol L 1 d 1 and did not differ seasonally. NH4 + turnover was dominated by assimilation into biomass in summer and by nitrification in winter and spring. In summer, rates were only slightly enhanced in the BBL and clearly related to particulate organic nitrogen and carbon concentrations, indicating particle attachment of nitrifiers and close coupling to organic matter degradation. The lack of correlations between nitrification and environmental variables in winter and spring suggested other regulatory mechanisms than in summer. Short-term changes, including the oxygenation of anoxic deep offshore water and particle resuspension clearly enhanced nitrification and further highlighted the variable mechanisms regulating nitrification in the Bay of Gdansk. Although nitrification rates did not greatly differ between seasons or water layers, the variability in regulatory mechanisms and the seasonal switch in NH4 + recycling are likely to have implications on coastal N-turnover and hence on the filter function of coastal waters.