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23501. 题目: Response of aggregate associated organic carbon, nitrogen and phosphorous to re-vegetation in agro-pastoral ecotone of northern China
文章编号: N19020201
期刊: Geoderma
作者: Yufei Yao, Nannan Ge, Si Yu, Xiaorong Wei, Xiang Wang, Jingwei Jin, Xuetong Liu, Mingan Shao, Yanchun Wei, Li Kang
更新时间: 2019-02-02
摘要: The agro-pastoral ecotone is an ecologically fragile transition zone and suffers from extensive human-induced land-use changes. To understand how soil organic carbon (OC) and nutrients will respond to re-vegetation practices in such an ecotone zone, we present the response of OC, nitrogen (N) and phosphorus (P) in both bulk soils and water-stable aggregates to typical re-vegetation patterns in an agro-pastoral ecotone of northern China. Three re-vegetation patterns, i.e., cropland converted to natural grassland, woodland and artificial grassland at different times (6 to 40 years), were selected. The paired croplands were also selected as the control for each re-vegetation pattern. The measured soil metrics include the proportions of each type of water-stable aggregate, the mean weight diameter and geometric mean diameter of the aggregates, and the concentrations of OC, N and P in bulk soils and each aggregate fraction. The results showed that the three re-vegetation patterns significantly increased the mass proportion of macro-aggregates, the values of mean weight diameter and geometric mean diameter, and the concentrations of OC and N in topsoils (0–10 cm). The accumulation of OC and N in bulk soils was mainly due to the accumulation in macro-aggregates. Furthermore, increases in OC and N were greater after conversion to legume vegetation than to non-legume vegetation, and were highest at approximately 20 years after the conversion. However, concentrations of P in bulk soils and aggregates were similar among the three re-vegetation patterns and the three aggregate fractions, and were minimally affected by the conversion. These results highlighted the potential of legume vegetation to increase OC and N in surface soils and aggregates, and indicated no response of soil P to re-vegetation in an agro-pastoral ecotone of northern China.

23502. 题目: Decoupled trophic responses to long‐term recovery from acidification and associated browning in lakes
文章编号: N19020114
期刊: Global Change Biology
作者: Taylor H. Leach, Luke A. Winslow, Nicole M. Hayes, Kevin C. Rose
更新时间: 2019-02-01
摘要: Increases in the concentration of dissolved organic matter (DOM) have been documented in many inland waters in recent decades, a process known as ‘browning’. Previous studies have often used space‐for‐time substitution to examine the direct consequences of increased DOM on lake ecosystems. However, browning often occurs concomitant with other ecologically important water chemistry changes that may interact with or overwhelm any potential ecological response to browning itself. Here we examine a long‐term (~20 year) dataset of 28 lakes in the Adirondack Park, New York, USA that have undergone strong browning in response to recovery from acidification. With these data, we explored how primary producer and zooplankton consumer populations changed during this time and what physical and chemical changes best predicted these long‐term ecosystem changes. Our results indicate that changes in primary producers are likely driven by reduced water clarity due to browning, independent of changes in nutrients, counter to previously hypothesized primary producer response to browning. In contrast, declines in calcium concomitant with browning play an important role in driving long‐term declines in zooplankton biomass. Our results indicate that responses to browning at different trophic levels are decoupled from one another. Concomitant chemical changes have important implications for our understanding of the response of aquatic ecosystems to browning.

23503. 题目: Characteristics of sediment affecting monomethylmercury accumulation in benthic fish of the Mekong Delta
文章编号: N19020113
期刊: Environmental Toxicology and Chemistry
作者: Hyojung Choi, Eunji Jeong, Viet Huu Nguyen, Dang Vu Bich Hanh, Nguyen Phuoc Dan, Kyung‐Hoon Shin, Seunghee Han
更新时间: 2019-02-01
摘要: The Mekong River Delta (Vietnam) is a flat, low‐lying area formed by a dense network of main tributaries of the Tien and Hau Rivers, providing a nourishing habitat for aquatic organisms. A sediment survey of the total mercury (Hg), monomethylmercury (MMHg), and geochemical variables was carried out from the coast to 131 km upriver to establish an overview of the environmental factors affecting the bioaccumulation of Hg and MMHg in delta fish. The survey results revealed that the total Hg (12–90 ng g^–1) and MMHg (0.014–1.5 ng g^–1) concentrations were in the range of uncontaminated sediment. Statistical analysis using various geochemical factors demonstrated that sediment MMHg concentrations and fractions of MMHg over total Hg in sediment were higher at sites with higher total organic carbon (TOC) and total nitrogen sites. The current levels of TOC in Mekong Delta sediment are relatively low (0.2–1.5%); however, expanding dam constructions and aquacultures related to salinity intrusion are reinforcing the carbon burial rate by increasing the fine fractions. Based on the positive relationship found between MMHg and TOC in sediment, proper management efforts are necessary to reduce MMHg production in the Mekong River Delta sediment. Environ Toxicol Chem 2018;9999:1–8. © 2018 SETAC

23504. 题目: Simultaneous adsorption and immobilization of As and Cd by birnessite-loaded biochar in water and soil
文章编号: N19020112
期刊: Environmental Science and Pollution Research
作者: Hong-Yan Wang, Peng Chen, Yong-Guan Zhu, Kuang Cen, Guo-Xin Sun
更新时间: 2019-02-01
摘要: A novel biochar was prepared by loading birnessite to improve its capability to simultaneously adsorb As(III), As(V), and Cd(II) in water and soil. Layer sheet–structured birnessite was successfully loaded onto the biochar surface with increased functional groups. SEM, XRD, and FTIR combining with XPS analysis were utilized to characterize birnessite-loaded biochar and its adsorption mechanisms for As and Cd(II). The saturated adsorption capabilities of the birnessite-loaded biochar (BRB) for As(III), As(V), and Cd(II) were as large as 3543, 2412, and 9068 mg/kg (calculated by Langmuir isotherm model), much higher than for the corresponding non-loaded biochar (no adsorption of As, 4335 mg/kg for Cd). Adsorption of Cd and As onto BRB was controlled by multi mechanisms; Cd(II) appeared to coordinate to vacant sites of birnessite, while As formed surface complex with functional groups. Furthermore, BRB showed higher abilities for co-adsorption of As(III) and Cd or As(V) and Cd, which may be due to the formation of Cd₃(AsO₄)₂ surface precipitate as well as synergistic reaction between anions and cations. After conditioning to soil, BRB showed potential for Cd and As remediation under both flooded and unflooded conditions. These results suggested that BRB can be used as an effective sorbent for simultaneous immobilization of heavy metals, especially As and Cd, in environmental and agricultural systems.

23505. 题目: Effects of biochar addition on the NEE and soil organic carbon content of paddy fields under water-saving irrigation
文章编号: N19020111
期刊: Environmental Science and Pollution Research
作者: Shihong Yang, Xiao Sun, Jie Ding, Zewei Jiang, Junzeng Xu
更新时间: 2019-02-01
摘要: The addition of biochar has been reported as a strategy for improving soil fertility, crop productivity, and carbon sequestration. However, information regarding the effects of biochar on the carbon cycle in paddy fields under water-saving irrigation remains limited. Thus, a field experiment was conducted to investigate the effects of biochar addition on the net ecosystem exchange (NEE) of CO₂ and soil organic carbon (SOC) content of paddy fields under water-saving irrigation in the Taihu Lake region of China. Four treatments were applied: controlled irrigation (CI) without biochar addition as the control (CA), CI with biochar addition at a rate of 20 t·ha⁻¹ (CB), CI with biochar addition at a rate of 40 t·ha⁻¹ (CC), and flooding irrigation (FI) with biochar addition at a rate of 40 t·ha⁻¹ (FC). Biochar addition increased rice yield and irrigation water use efficiency (IWUE) by 24.0–36.3 and 33.4–42.5%, respectively, compared with the control. In addition, biochar addition increased the NEE of CI paddy fields. The average NEE of paddy fields under CB and CC was 2.41 and 30.6% higher than that under CA, respectively. Thus, the increasing effect of biochar addition at a rate of 40 t·ha⁻¹ was considerably better than those of the other treatments. Apart from biochar addition, irrigation mode was also identified as an influencing factor. CI management increased the NEE of paddy fields by 17.6% compared with FI management. Compared with CA, CB increased total net CO₂ absorption by 10.0%, whereas CC decreased total net CO₂ absorption by 13.8%. Biochar addition also increased SOC, dissolved organic carbon, and microbial biomass carbon contents. Therefore, the joint regulation of biochar addition and water-saving irrigation is a good technique for maintaining rice yield, increasing IWUE, and promoting soil fertility. Furthermore, when amended at the rate of 20 t·ha⁻¹, biochar addition will be a good strategy for sequestering carbon in paddy fields.

23506. 题目: Identification of toxicants from a highly C10–C40 contaminated sediment influenced by the wood industry: Petroleum hydrocarbons or biogenic organic compounds?
文章编号: N19020110
期刊: Environmental Toxicology and Chemistry
作者: Mari Dahl, Suvi Survo, Pia Välitalo, Grit Kabiersch, Olga‐Sofia Alitalo, Olli‐Pekka Penttinen, Anna‐Lea Rantalainen
更新时间: 2019-02-01
摘要: Sediment from a log pond located in south Finland contained 15,000 to 50,000 mg/kg dw of C₁₀–C₄₀ hydrocarbons. It was unclear whether they originated from the hydraulic fluid of the log hoist or the wood extractives. In the present study, methods of effect‐directed analysis were used for the identification of toxicants. A combination of fractionation, biotesting and chemical analyses revealed that the key toxicant of log pond sediment was retene, a dialkyl‐substituted phenanthrene derived from wood resin acids. Additionally, the most toxic fraction included three other wood‐originated diterpenic compounds. Typical wood extractives such as sesquiterpenes and odd‐carbon number alkanes in the range C₂₁–C₃₃ were identified in the fraction, which showed minor genotoxic potency. The most polar fraction contained triterpenes and showed estrogenic activity. No evidence for the presence of hydraulic fluid in sediment was found. The study also indicated that in cases where the organic matter content of sediment or soil is high, using the results of standard mineral oil analysis in risk management can lead to incorrect actions, because standard methods do not differentiate petroleum hydrocarbons from biogenic hydrocarbons. This article is protected by copyright. All rights reserved

23507. 题目: Organic matter quantity and quality across salinity gradients in conduit‐ vs. diffuse flow‐dominated subterranean estuaries
文章编号: N19020109
期刊: Limnology and Oceanography
作者: Andrea J. Pain, Jonathan B. Martin, Caitlin R. Young, Laibin Huang, Arnoldo Valle‐Levinson
更新时间: 2019-02-01
摘要: Submarine groundwater discharge (SGD) is a source of water and bioreactive solutes to coastal zones but may be modified by organic matter (OM) remineralization dynamics within subterranean estuaries (STEs). We hypothesize that bioreactive solute fluxes should depend on water residence time in STEs, but links between OM transformations and residence time in STEs are poorly characterized. To test this hypothesis, we compare dissolved OM (DOM) quantity and quality in two hydrologically distinct STE systems: a reef lagoon on the east coast of the Yucatan Peninsula, Mexico, where semidiurnal mixing in submarine springs of a carbonate karst aquifer results in short residence times, and a barrier lagoon on the east coast of Florida, where slow flow through siliciclastic sediments results in long residence times. We measured dissolved organic carbon concentrations and characterized colored DOM (CDOM) with ultraviolet spectroscopy and fluorescence combined with Parallel Factor Analysis. Both sites exhibit similar shifts in OM quality with salinity and reflect a marine source of labile OM to the STEs. Nonconservative mixing and CDOM production occurs at all sites but the long water residence times in the siliciclastic STEs cause orders of magnitude greater production than the carbonate STE. Consistent CDOM production across sites with disparate characteristics indicates that STEs are common sources of CDOM to surface water. However, observed variation in the magnitudes of CDOM production indicates that estimating global, and even regional, solute fluxes associated with SGD will be complicated by hydrologic control on extents of OM remineralization.

23508. 题目: Structural and functional differentiation of the microbial community in the surface and subsurface peat of two minerotrophic fens in China
文章编号: N19020108
期刊: Plant and Soil
作者: Meng Wang, Jianqing Tian, Zhaojun Bu, Louis J. Lamit, Huai Chen, Qiuan Zhu, Changhui Peng
更新时间: 2019-02-01
摘要: Background and aims: Microbial communities are the primary drivers of organic matter decomposition in peatlands. However, limited knowledge is available regarding depth-dependent microbial community structure and function in East Asian peatlands, using cultivation independent approaches. Methods: We investigated the vertical stratification of prokaryote and fungal communities in a moderately rich fen in northeast China (Hani) and a rich fen in southwest China (Riganqiao). Results: Fungal and prokaryotic operational taxonomic unit (OTU) composition exhibited strong site and/or depth responses. Prokaryotic OTUs exhibited the greatest alpha diversity at the mesotelm ‘hot spot’, whereas the predicted metagenomic metabolic functions did not align with the pattern of prokaryote alpha diversity. The large cover of shrubs contributed to a greater relative abundance of ericoid- and ecto-mycorrhizal fungi at Hani, whereas Riganqiao showed more arbuscular mycorrhizal fungi. Soil pH and water table depth were among the predominant abiotic factors associated with microbial community composition. Conclusions: Projected shifts in hydrology and/or vegetation with global change may cause substantial impacts on peatland microorganisms and thus the associated biogeochemistry. It is critical to better understand the mechanism of the discrepancy between microbial community structure and the functions at the mesotelm ‘hot spot’ when evaluating the ecosystem functions in peatlands.

23509. 题目: The metabolic and genetic diversity of soil bacterial communities depends on the soil management system and C/N dynamics: The case of sustainable and conventional olive groves
文章编号: N19020107
期刊: Applied Soil Ecology
作者: Adriano Sofo, Patrizia Ricciuti, Catia Fausto, Alba N. Mininni, Carmine Crecchio, Marina Scagliola, Anna Daniela Malerba, Cristos Xiloyannis, Bartolomeo Dichio
更新时间: 2019-02-01
摘要: Under Mediterranean type climates, a sustainable soil management aimed at increasing soil organic carbon and microbiological diversity is of key importance. The aim of this study was to characterize and compare soils from a mature Mediterranean olive (Olea europaea L.) orchard subjected to two different soil management systems (sustainable, S_mng, and conventional, C_mng) for 18 years. Composite soil samples were analyzed qualitatively (pedological determinations) and quantitatively (soil C, N and pH). Bacterial metabolic activity and diversity were evaluated spectrophometrically by the Biolog® assay, while 16S-based metagenomics analysis was used to analyse the abundance of N-cycling bacteria. From the general analysis of the data obtained by the study of soil profiles and litter, C and N dynamics, and the genetic and functional diversity of soil bacteria, it emerged that the S_mng system caused an improvement in soil organic matter in the topsoil layers, compared to the C_mng system, with consequent increases in the abundance of soil N-cycling bacteria but without affecting the indices related to total bacterial metabolic activity and diversity. The results obtained could promote the development of new approaches for optimizing soil carbon cycling, managing nutrient transport, and sustaining and improving olive yield and quality.
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23510. 题目: Treatment of organic wastewater containing nitrogen and chlorine by combinatorial electrochemical system: Taking biologically treated landfill leachate treatment as an example
文章编号: N19020106
期刊: Chemical Engineering Journal
作者: Yang Deng, Nan Chen, Chuanping Feng, Fangxin Chen, Haishuang Wang, Peijing Kuang, Zhengyuan Feng, Tong Liu, Yu Gao, Weiwu Hu
更新时间: 2019-02-01
摘要: This study presents a combinatorial electrochemical system (CES) for the treatment of refractory organic wastewater containing nitrogen and chloride ion. The CES was composed of iron anode reactor (IAR), Ti/RuO₂ anode reactor (TAR) and available chlorine removal reactor (CRR). Biologically treated landfill leachate (BTLL) was selected as the treatment object to evaluate the performance of CES. The results showed that CES could simultaneously remove chemical oxygen demand (COD) and total nitrogen (TN) by 94.6% and 98.3%, respectively. Reduction of nitrite-N by cathode in IAR and oxidation of ammonium-N by available chlorine in TAR were the major pathways for TN removal. Fluorescence spectroscopy and parallel factor analysis (PARAFAC) showed that the main organic components in BTLL were humic-like substances and soluble microbial degradation products. These substances were removed by CES and the remaining organics were some hydrocarbons and carboxylic acids. The available chlorine was rapidly reduced into chloride ion by IAR precipitates, thus decreasing the cytotoxicity. In addition, the formation of stable Fe³⁺ crystals was promoted by the oxidation of available chlorine in CRR, which increased the density of the precipitates and reduced their volume. Therefore, the CES is a promising solution for the treatment of refractory organic wastewater containing nitrogen and chlorine ion.
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23511. 题目: A novel magnetic biochar/MgFe-layered double hydroxides composite removing Pb²⁺ from aqueous solution: isotherms, kinetics and thermodynamics
文章编号: N19020105
期刊: Colloids and Surfaces A: Physicochemical and Engineering Aspects
作者: Yang Jia, Yingshuang Zhang, Jiangang Fu, Liangxiao Yuan, Zheng Li, Chang Liu, Di Zhao, Xiaobo Wang
更新时间: 2019-02-01
摘要: An absorbent, magnetic biochar supporting MgFe-Layered double hydroxides (MgFe-LDH) composites was synthesized to remove Pb²⁺ from the aqueous solution. The results of SEM, EDS, XRD, FT-IR, XPS, VSM and BET determinations showed that MgFe-LDH was successfully loaded on the magnetic biochar by hydrothermal synthesis. These characterizations also indicated that the adsorption of Pb²⁺ resulted from co-precipitation between interlayer anions, surface hydroxyl groups and Pb²⁺. The isotherms study revealed that the adsorption of Pb²⁺ on magnetic biochar/MgFe-LDH was well fitted to Langmuir model. The maximum adsorption capacity was 476.25 mg g^-1 at 25 °C. Kinetic and thermodynamic studies indicated that the adsorption process was a spontaneous endothermic reaction and limited by chemisorption. Owing to the simple synthesis, superior adsorption capacity, good magnetic properties and cyclic utilization, the magnetic biochar/MgFe-LDH is a promising adsorbent for removing Pb²⁺ from aqueous solution.
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23512. 题目: Biodegradation of methylene blue dye in a batch and continuous mode using biochar as packing media
文章编号: N19020104
期刊: Environmental Research
作者: Vikash Bharti, Kumar Vikrant, Mandavi Goswami, Himanshu Tiwari, Ravi Kumar Sonwani, Jechan Lee, Daniel C.W. Tsang, Ki-Hyun Kim, Mohd Saeed, Sunil Kumar, Birendra Nath Rai, Balendu Shekher Giri, Ram Sharan Singh
更新时间: 2019-02-01
摘要: Bacterial species for metabolizing dye molecules were isolated from dye rich water bodies. The best microbial species for such an application was selected amongst the isolated bacterial populations by conducting methylene blue (MB) batch degradation studies with the bacterial strains using NaCl-yeast as a nutrient medium. The most suitable bacterial species was Alcaligenes faecalis (A. faecalis) according to 16 S rDNA sequencing. Process parameters were optimized and under the optimum conditions (e.g., inoculum size of 3 mL, temperature of 30 °C, 150 ppm, and time of 5 days), 96.2% of MB was removed. Furthermore, the effectiveness for the separation of MB combining bio-film with biochar was measured by a bio-sorption method in a packed bed bioreactor (PBBR) in which microbes was immobilized. The maximum MB removal efficiencies, when tested with 50 ppm dye using batch reactors containing free A. faecalis cells and the same cells immobilized on the biochar surface, were found to be 81.5 and 89.1%, respectively. The PBBR operated in continuous recycle mode at high dye concentration of 500 ppm provided 87.0% removal of MB through second-order kinetics over 10 days. The % removal was found in the order of PBBR>Immobilized batch>Free cell. The standalone biochar batch adsorption of MB can be described well by the pseudo-second order kinetics (R² ≥ 0.978), indicating the major contribution of electron exchange-based valence forces in the sorption of MB onto the biochar surface. The Langmuir isotherm suggested a maximum monolayer adsorption capacity of 4.69 mg g^-1 at 40 °C which was very close to experimentally calculated value (4.97 mg g^-1). Moreover, the Casuarina seed biochar was reusable 5 times.

23513. 题目: Impact of Dissolved Organic Matter on Mercury and Methylmercury Sorption to Activated Carbon in Soils: Implications for Remediation
文章编号: N19020103
期刊: Environmental Science: Processes Impacts
作者: Grace Schwartz, James Sanders, Alyssa McBurney, Steven S Brown, Upal Ghosh, Cynthia Gilmour
更新时间: 2019-02-01
摘要: Activated carbon (AC) amendments have shown promise in reducing inorganic mercury (Hg) and methylmercury (MeHg) risk in contaminated soils. However, the effectiveness of AC in Hg and MeHg immobilization has varied among studies, suggesting that site biogeochemistry might dictate efficacy. In this study, we examine the effect of dissolved organic matter (DOM) on MeHg and Hg partitioning to AC. We evaluated the impact of Suwannee River Humic Acid (SRHA) on AC partitioning directly using an isotherm approach, and also evaluated DOM impacts on AC sorption in an estuarine marsh soil using slurry microcosms. Aqueous partition coefficients for Hg-SRHA and MeHg-SRHA complexes to AC (KAC) were one to two orders of magnitude lower than those for chloride complexes and more closely resembled the KAC of SRHA. In anaerobic, sulfidic soil slurries, we found that AC significantly reduced porewater concentrations of both ambient MeHg and a fresh Me199Hg spike and that the addition of up to 60 mg/L SRHA did not reduce AC efficacy. For inorganic Hg (both ambient Hg and fresh 201Hg spike), AC was also effective in reducing porewater concentrations, but SRHA reduced the magnitude of KAC in a concentration-dependent manner. We hypothesize that SRHA impacted Hg KAC in soils by interfering with HgS precipitation. For both Hg and MeHg, the KAC for sulfide species appears stronger than for chloride or SRHA species. This study highlights the need for site-specific evaluation of AC efficacy and the value in developing biogeochemical models of AC performance for Hg.

23514. 题目: Coupled iron and phosphorus release from seasonally hypoxic Louisiana shelf sediment
文章编号: N19020102
期刊: Estuarine, Coastal and Shelf Science
作者: Neha A. Ghaisas, Kanchan Maiti, John R. White
更新时间: 2019-02-01
摘要: Phosphorus (P) cycling in the coastal ocean along deltaic coastlines is predominantly controlled by river discharge and biogeochemical properties of the sediments. In the Louisiana shelf, sediment biogeochemistry is strongly influenced by seasonally-fluctuating bottom water O₂, which, can potentially transition the shelf sediments from being a sink to source of P. Sediment P fluxes determined using persistent anaerobic and aerobic intact core incubations were 11.46 ± 3.2 mg m⁻² d⁻¹ and 0.67 ± 0.16 mg m⁻² d⁻¹ respectively, indicating a 17 times greater P efflux from O₂-deprived sediments. During the transition from aerobic to anaerobic conditions, the high sedimentary O₂ consumption rate of 889 ± 33.6 mg m⁻² d⁻¹ resulted in a progressive decrease in the dissolved O₂ in the overlying water, leading to a sediment P flux of 7.2 ± 5.5 mg m⁻² d⁻¹, which was mostly driven by P release towards the end of the incubation when the overlying water became near anoxic. This P flux led to a 34.6% loss in sedimentary Fe-bound P during the two-day incubation period which underscores the importance of coupled FeP biogeochemistry and O₂ penetration depth in a coastal hypoxia setting. The high DIN: DIP ratio of river water (∼50:1; P limited) coupled with high potential release of P from the shelf sediments can further increase primary production, further exacerbating hypoxic conditions though increased organic matter (OM) deposition and subsequent decomposition.
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23515. 题目: Low-femtogram sensitivity analysis of polyaromatic hydrocarbons using GC-APLI-TOF mass spectrometry: Extending the target window for aromatic steroids in early Proterozoic rocks
文章编号: N19020101
期刊: Organic Geochemistry
作者: Arne Leider, Sigrid Richter-Brockmann, Benjamin J. Nettersheim, Christine Achten, Christian Hallmann
更新时间: 2019-02-01
摘要: Reading the molecular record of early life on Earth can be challenging as a consequence of the thermal decomposition of biomarker hydrocarbons during extended and deep sedimentary burial. Biomarkers that appear absent may still exist in concentrations far below the detection limit of regular analytical techniques. Hence thermal maturation and analytical limitations form a major hurdle for the unambiguous reconstruction of Earth’s earliest ecosystems. Specific degradation products of hopanes and steranes might still carry diagnostic value for the reconstruction of past biota when found in mature oils and sediment extracts, but their concentrations are often exceedingly low. We here report on the use of gas chromatography–time-of-flight-mass spectrometry with laser ionization at atmospheric pressure (GC-APLI-TOF-MS) for the identification and quantification of aromatic steroids. GC-APLI-TOF-MS analyses of a reference oil revealed that triaromatic steroids (TAs) can be detected with significantly higher sensitivity and selectivity compared to commonly used electron impact ionization GC-MS in selected ion monitoring mode, while the limit of detection for retene was as low as 25 fg on column. Paleoproterozoic (1.64 Ga) sedimentary rocks of the Barney Creek Formation yield the so far oldest unambiguous aromatic steroids. GC-APLI-TOF-MS applied to these rocks revealed the presence of TAs in even deeper parts of this succession, where they are represented by short chain homologues only. While the TA-I/(TA-I + TA-II) parameter is principally controlled by thermal degradation of longer chain homologues, the complete disappearance of TA-II already at 435-442 °C T_max, may point towards an uncommon thermal gradient in the Barney Creek Formation or towards other influencing factors. GC-APLI-TOF-MS proves to be a highly promising tool that might extend molecular geobiological approaches to older sedimentary basins that were hitherto precluded from organic geochemical approaches by their elevated thermal maturity.
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23516. 题目: Biological resources in the Sea of Okhotsk Large Marine Ecosystem: Their status and commercial use
文章编号: N19013110
期刊: Deep Sea Research Part II: Topical Studies in Oceanography
作者: V.p. Shuntov, O.a. Ivanov, E.p. Dulepova
更新时间: 2019-01-31
摘要: The ecosystem studies of biological resources in the Sea of Okhotsk Large Marine Ecosystem (LME), launched by the Pacific Research Fisheries Center (TINRO-Center) in the 1980s, are considered in this brief review. Quantitative data on biomass, distribution density and diet of plankton, benthos, nekton, and nektobenthos were collected annually on three to five integrated expeditions annually covering all seasons. These studies show that the biological capacity and the stock size of commercial aquatic species have always been underestimated. According to the latest estimates, the total organic matter produced annually ranges within 17.85–23.9 billion tons of wet weight, of which the primary production accounts for 63–78%. Production of other components is: microzooplankton, up to 2100.0 million t; bacterioplankton, to 5200.0 million t; euryphagous zooplankton (mainly euphausiids and copepods), to 2520.0 million t; predatory zooplankton, to 480.0 million t; zoobenthos, to 340.0 million t; nekton, to 22.7 million t; nektobenthos, to 2.2 million t; marine mammals and birds, 0.1 million t. The stock status of most species of fish and invertebrates are considered to be in good or satisfactory shape. Fishing is regulated based on the precautionary approach. The current annual commercial catch is 1.5–1.7 million tons. In the absence of harvesting of marine mammals, the populations of cetaceans, pinnipeds and sea otter have recovered.

23517. 题目: Seasonality of archaeal lipid flux and GDGT-based thermometry in sinking articles of high latitude oceans: Fram Strait (79° N) and Antarctic Polar Front (50° S)
文章编号: N19013109
期刊: Biogeosciences
作者: Eunmi Park, Jens Hefter, Gehard Fischer, Morten H. Iversen, Simon Ramondenc, Eva-Maria Nöthig, and Gesine Mollenhauer
更新时间: 2019-01-31
摘要: The relative abundance of individual archaeal membrane lipids, namely of glycerol dialkyl glycerol tetraethers (GDGTs) with the different number of cyclopentane rings, varies with temperature, which enabled their use as paleotemperature proxy. The first GDGT-based index in marine sediments called TEX₈₆ is believed to reflect mean annual sea surface temperature (maSST). The TEX₈₆^L is an alternative temperature proxy for low temperature regions (<15°C), where the original TEX₈₆ proxy suffers from scattering in a linear calibration with SSTs. However, TEX₈₆^L-derived temperatures still display anomalous estimates in polar regions. In order to elucidate the potential cause of the disagreement between TEX₈₆^L estimate and SST, we analyzed GDGT fluxes and TEX₈₆^L-derived temperatures in sinking particles collected with time-series sediment traps in high northern and southern latitude regions. At 1296m depth in the eastern Fram Strait (79°N), a combination of various transporting mechanisms for GDGTs might result in seasonally different sinking velocities for particles carrying these lipids, resulting in strong variability in the TEX₈₆^L signal. The similarity of flux weighted TEX₈₆^L temperatures from sinking particles and surface sediments implies an export of GDGTs without alteration during transport in the Fram Strait. The estimated temperatures correspond to temperatures in water depths of 30–80m, where nitrification might occur, indicating the favorable depth habitat of Thaumarchaeota. In the Antarctic Polar Front of the Atlantic sector (50°S), TEX₈₆^L-derived temperatures displayed warm and cold biases compared to satellite-derived SSTs at 614m depth, and its flux-weighted mean signal differs from the deep signal at 3196m. TEX₈₆^L-derived temperatures at 3196m depth and the surface sediment showed up to 7°C warmer temperatures relative to satellite-derived SST. Such a warm anomaly might be caused by GDGT contributions from Euryarchaeota, which are known to dominate archaeal communities in the circumpolar deep water of the Antarctic Polar Front. The other reason might be that a linear calibration is not appropriate for this frontal region. Of the newly suggested SST proxies based on hydroxylated GDGTs (OH-GDGTs), only those with OH-GDGT−0 and Crenarchaeol or the ring index (RI) of OH-GDGTs yield realistic temperature estimates in our study regions, suggesting that OH-GDGTs could be applied as a potential temperature proxy in high latitude oceans.

23518. 题目: Tracking multiple aromatic compounds in a full-scale coking wastewater reclamation plant: Interaction with biological and advanced treatments
文章编号: N19013108
期刊: Chemosphere
作者: Jing Ren, Jianfeng Li, Jianguo Li, Zuliang Chen, Fangqin Cheng
更新时间: 2019-01-31
摘要: Aromatic compounds are widely contained in coking wastewater (CWW), drawing great attention due to their potential risks to environment and human health. Integrated systems combining biological processes with advanced treatments are the current trend of CWW reclamation. However, the variations of aromatic composition throughout these processes are poorly understood. This study investigated the occurrence, fate and removal of aromatic compounds in a full scale CWW reclamation plant with eight treatment stages by gas chromatography–mass spectrometry and optical spectrum. The results showed that polycyclic aromatic hydrocarbons (PAHs), phenols and heterocyclic compounds accounted for 38.9%, 33.5% and 22.6% of the total organics in CWW, respectively. Among them, PAHs were more sensitive to anaerobic digestion, while phenols and heterocyclics had higher bioavailability in aerobic process. Although more than 90% DOC could be removed in biological processes, the bio-effluent was still brown in color, implying the residues of aromatics to the advanced treatments. The interaction between the bio-refractory organics and the advanced treatments suggested that multiple aromatic compounds were selectively removed along the treatment train. Specifically, coagulation, sand filtration, ultrafiltration, adsorption, nanofiltration and reverse osmosis were found to be highly related to the elimination of residual isoquinoline, phenol, cresol, fluoranthene, benzene and humic-like organics, correspondingly. Findings in this study indicated that adsorption was a key step for removing chromophoric PAHs with more aromatic rings, while fouling control in the end-point membrane systems should be focused on the elimination of BTEXs and humic-like substances.
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23519. 题目: Ca²⁺ complexation of dissolved organic matter in arid inland lakes is significantly affected by drastic seasonal change of salinity
文章编号: N19013107
期刊: Science of The Total Environment
作者: Daoyong Zhang, Qinghua Lin, Nana Xue, Pengfeng Zhu, Fan Zhang, Chang Ge, Chaojie Ma, Xiangliang Pan
更新时间: 2019-01-31
摘要: CaCO₃ precipitation is one of the most common and important geochemical processes in the arid inland waters and it can be significantly affected by interaction of DOM with Ca²⁺. Effects of the drastic seasonal change of water salinity on interaction of DOM with Ca²⁺ in the arid inland waters were completely unknown. In the present study, complexation of DOM with Ca²⁺ in the freshwater (0.5‰ salinity) and hypersaline water (70‰ salinity) were comparatively examined by excitation-emission matrix (EEM) fluorescence quenching titration and isothermal titration calorimetry (ITC). The complexation of DOM with Ca²⁺ was significantly influenced by the drastic change of salinity. The ITC complexation is exothermic at 0.5‰ salinity but turns to an endothermic process at 70‰ salinity. More energy is needed for the complex reaction between DOM and Ca²⁺ under the hypersaline condition than in the fresh water. Fluorescence quenching titration indicates that DOM has stronger binding ability toward Ca²⁺ in the freshwater than in the saline water, and more fractions of DOM in the freshwater are accessible to Ca²⁺ than in the saline water. Ca²⁺ complexation in the DOM is dominated by the tryptophan-like components at both salinities and the complexation of Ca²⁺ with fulvic acid-like components is ignorable. The findings is important for understanding the aquatic geochemical processes in some lakes that seriously affected by irrigation water use in the arid zone.
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23520. 题目: Long-term greenhouse vegetable cultivation alters the community structures of soil ammonia oxidizers
文章编号: N19013106
期刊: Journal of Soils and Sediments
作者: Xing Liu, Ying Zhang, Xiujuan Ren, Bihua Chen, Changwei Shen, Fei Wang
更新时间: 2019-01-31
摘要: Purpose: Continuous cropping obstacles derived from long-term intensive cultivation has severely affected the healthy development of greenhouse vegetable industry in China. The alterations in soil microbial communities are commonly thought to be the important reasons behind continuous cropping obstacles. However, little attention is focused on soil functional microorganisms, such as soil ammonia oxidizers, which convert NH₃ to NO₂⁻ in soils and play an important role in terrestrial ecosystem N cycling. Materials and methods: With the help of quantitative real-time PCR and high-throughput sequencing methods, this study investigated the effects of consecutive greenhouse vegetable cultivation on the abundances and community structures of ammonia-oxidizing archaea (AOA) and bacteria (AOB). Results and discussion: Continuous greenhouse production significantly affected soil physicochemical properties but slightly influenced on soil biochemical properties. Long-term greenhouse production significantly decreased soil potential nitrification rates. The abundances of AOA and AOB were insensitive to continuous greenhouse cultivation, whereas their community structures were significantly altered. A significant increase in average relative abundance of Nitrososphaerales Clade B4 in AOA community was observed after long-term greenhouse cultivation but just the opposite for Nitrososphaerales Clade Nitrososphaera. Increasing greenhouse cultivation years decreased the average relative abundance of Nitrosospira in AOB community, and their ecological niches were gradually occupied by Nitrosomonas; consequently, Nitrosomonas dominated AOB community under long-term greenhouse vegetable cultivation. Soil physicochemical properties, but not biological activity, were directly linked to the shifts of community structures of ammonia oxidizers. Moisture and total nitrogen significantly regulated AOA community structure, whereas organic matter and salinity mediated that of AOB. Conclusions: Our results demonstrated that consecutive greenhouse production obviously affected soil N turnover through altering community structures of nitrifiers, and soil functional microorganisms should be taken more attention when exploring the mechanisms for continuous cropping obstacles of greenhouse vegetable. The current study also highlights the fast adaptation of both AOA and AOB communities to complexly varied soil physicochemical environments.