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22741. 题目: Effect of land use changes on soil microbial enzymatic activity and soil microbial community composition on Maryland's Eastern Shore
文章编号: N20111214
期刊: Applied Soil Ecology
作者: Elizabeth A.B. Emmert, Samuel B. Geleta, Chelsi M. Rose, Gloria E. Seho-Ahiable, Ashley E. Hawkins, Keirsten T. Baker, Amanda S. Evans, Mercedes E. Harris, Abigayle C. Mrozinski, Michael E. Folkoff, Philip D. Anderson, Christopher H. Briand
更新时间: 2020-11-12
摘要: We compared microbial enzymatic activity and community composition in small, undisturbed, family cemetery soils and surrounding agricultural fields or suburban lawns to determine the effect of land use changes on soil biology. We collected soil from seven sites in Wicomico County, Maryland monthly for one year. Fluorescein diacetate (FDA) hydrolysis and dehydrogenase activity were significantly greater in the cemetery soils compared to field soils (agricultural and lawn) 63% and 30% of the time, respectively. Much less frequently the field soils had significantly higher microbial activity compared to the cemetery soils (10% of sample pairs for both FDA and dehydrogenase). FDA activity measurements were highest in the spring and lowest in late summer at all seven sites, while no seasonal variation was evident for dehydrogenase activity. Dominant bacterial phyla in the soils were similar between field and cemetery sites with the exception of Gemmatimonadetes having higher relative abundance in fields. Fourteen genera differed in relative abundance between cemeteries and fields, and the relative abundance of these genera correlated with soil pH, organic matter, and phosphorus levels. There was no difference in phylotype richness or diversity between fields and cemetery soils. Based on FDA hydrolysis, microbial activity is greater in cemetery soils, providing evidence to suggest land use changes have altered the biological properties of these soils.

22742. 题目: Phytotoxicity of hydrochars obtained by hydrothermal carbonization of manure-based digestate
文章编号: N20111213
期刊: Journal of Environmental Management
作者: Silvia Celletti, Alex Bergamo, Vittoria Benedetti, Matteo Pecchi, Francesco Patuzzi, Daniele Basso, Marco Baratieri, Stefano Cesco, Tanja Mimmo
更新时间: 2020-11-12
摘要: The management of digestate, the main by-product of the anaerobic digestion (AD) process, is one of the most serious environmental issues. Although digestate is used on arable land as a fertilizer, it can have a negative impact on the environment due to nitrate leaching into the groundwater and ammonia volatilization into the atmosphere, with high economic and environmental disposal costs. Therefore, hydrothermal carbonization (HTC), a thermochemical biomass conversion process, could represent a sustainable and efficient alternative for digestate management. Hydrochar, the solid product of the HTC process, has been recently proposed as a plant growing medium in soilless culture systems (SCS). Here, using cow manure digestate as feedstock, we investigated the influence of the HTC process reaction temperature (180, 220 and 250 °C) and residence time (1 and 3 h) on the physical-chemical properties (pH, electrical conductivity, and mineral element concentrations) of the resulting hydrochars. Furthermore, in order to fully valorize hydrochar as a growing medium, their possible phytotoxic effects and those of their water extracts (prepared at two different concentrations and at different pHs) were tested in germination tests with cress seeds (Lepidium sativum L.). Concentrations of nutrients, heavy metals, organic acids, sugars and furan compounds were determined in the water extracts. Characterization analysis of these hydrochars revealed that they can be distinguished from each other by their physical-chemical properties, which were significantly affected by the two process parameters. Specifically, the HTC temperature had a greater effect on the composition of hydrochars than the residence time. Germination tests found hydrochar water extracts to show significantly lower phytotoxicity than the hydrochars themselves. Notably, the phytotoxic effect of the extracts decreased with increasing extraction ratio and decreasing pH. The chromatographic characterization of extracts identified the presence of potential phytotoxins, such as furan compounds (i.e., hydroxymethylfurfural and furfural). However, before using hydrochars as potential and innovative growing media for plants, their phytotoxicity should be limited, for example through their dilution with other substrates. Overall, AD-HTC coupling could represent a valuable eco-sustainable expedient in the field of biomasses, green economy and waste conversion and, therefore, further investigations in this direction are necessary.

22743. 题目: Reactive oxygen species alter chemical composition and adsorptive fractionation of soil-derived organic matter
文章编号: N20111212
期刊: Geoderma
作者: Kaizad F. Patel, Václav Tejnecký, Tsutomu Ohno, Vanessa L. Bailey, Rachel L. Sleighter, Patrick G. Hatcher
更新时间: 2020-11-12
摘要: Reactive oxygen species (ROS), formed during redox fluctuations in iron-rich soils, have been known to stimulate lignin degradation, although not much is known about how they alter soil organic matter (SOM) composition and interaction with mineral surfaces. We conducted a laboratory experiment to see how ROS altered SOM composition and adsorptive fractionation onto Fe-mineral surfaces. We reacted water extracts of SOM with ·OH, produced by the Fenton reaction, and then conducted a sorption experiment of the extracts with goethite to analyze the amount and quality of SOM adsorbed. The Fenton reaction preferentially consumed low-O, mostly aromatic molecules, and new high-O molecules were detected post-Fenton, nearly half of which were carbohydrate-like. Although the amount of C adsorbed did not change after oxidation, the post-Fenton adsorbed molecules were more oxidized. Pre-Fenton adsorption was dominated by aromatic molecules (90%), but post-Fenton, the adsorbed molecules were 75% aromatic and 25% carbohydrate-like. We show that the ·OH radical oxidized SOM and shifted patterns of adsorption to a more oxidized pool. Because adsorption to minerals is thought to stabilize SOM, our results suggest that ROS may alter the availability and stabilization patterns of SOM.

22744. 题目: Influence of basin-wide geomorphology on arsenic distribution in Nadia district
文章编号: N20111211
期刊: Environmental Research
作者: Ayan Das, Santanu Majumder, Sandipan Barman, Debashis Chatterjee, Sutapa Mukhopadhyay, Pinaki Ghosh, Chandra Nath Pal, Gopinath Saha
更新时间: 2020-11-12
摘要: The present study depicts the geospatial relation between basinal geomorphology and heterogeneous arsenic (As) distribution in the Bengal Delta Plain (BDP). The distribution pattern largely varies throughout the study area (higher: Karimpur-II AsT average 214.73 μgL−1; lower: Tehatta AsT average 27.84 μgL−1). Both safe (low As) and unsafe (high As) areas are identified within the single shallow aquifer (<50 m), where they are in close vicinity. Statistical analysis shows that Padma river basin is the most contaminated (AsT avg. 214.7 ± 160 μgL−1) and Churni-Ichhamati river basin (AsT avg. 108.54 ± 89.43 μgL−1) is the least contaminated with groundwater As. Moreover, the role of geomorphological features influencing the geospatial distribution of As has been studied and meandering features are found to correlate with high As wells (r2 = 0.52), whereas, natural levees are correlated with safer wells (r2 = 0.57). In the meandering features, the deposition of sedimentary organic matter (SOM) facilitates the reduction of As bearing Fe(III) oxy-hydroxides and subsequent higher As mobilization. In natural levees, surface derived labile organic matter (DOC and FOM, Fresh Organic Matter) from different land-use patterns (Habitation, degraded waterbodies, cattle dwelling, sanitation, etc.) is transported to shallow aquifers (notably protein rich leakage sewage). The fresh organic carbon transported to the shallow aquifers, thereby triggering As release by microbe-mediated reductive dissolution of hydrated Fe(III)-oxides (HFO). Iron reduction (mostly amorphous) is playing an important role in the release of As depending on basin-wise sedimentation pattern, local recharge, accumulation of silt/clay/micas at the top with corresponding reactive oxidation of organic carbon. These are important components and often helping the cyclic water-rock interaction of As causing such heterogeneous geospatial distribution. The delineation of aquifer with regard to safer and unsafe areas would immensely help to supply safe drinking water to the rural community.

22745. 题目: Enhanced Winter Carbon Export Observed by BGC‐Argo in the Northwest Pacific Ocean
文章编号: N20111210
期刊: Geophysical Research Letters
作者: Xiaogang Xing, Mark L. Wells, Shuangling Chen, Sheng Lin, Fei Chai
更新时间: 2020-11-12
摘要: The winter‐ and spring‐time mixed‐layer pump (MLP) significantly augments the global carbon transport from the surface mixed layer to deeper waters when ephemeral surface phytoplankton blooms are repeatedly mixed to depth. Exploiting unusual 190 + daily BGC‐Argo profiling measurements within a recirculation gyre, we show repetitive MLP episodes generating a January–March averaged particulate organic carbon (POC) export of ~110 mg C m−2 day−1 in the midlatitude (31°N) Northwest Pacific. Subsampling this dataset on a 5‐ or 10‐day cycle yielded an order of magnitude less export, or even totally missed all the MLP events. The evidence here supports the need for new strategies if the BGC‐Argo program is to adequately quantify ocean carbon cycling and its effects on biological systems. We propose that a handful of floats be tasked with daily profiling, and machine learning strategies be used to link these data with satellite derived measurements to estimate the synoptic‐scale MLP export.

22746. 题目: Direct Measurements of the Forces between Silver and Mica in Humic Substance-Rich Solutions
文章编号: N20111209
期刊: Environmental Science & Technology
作者: Janis E. Patiño, Tonya L. Kuhl, Verónica L. Morales
更新时间: 2020-11-12
摘要: Deposition of engineered nanoparticles onto porous media from flowing suspensions is important for soil and groundwater quality. The deposition mechanism is controlled by interaction forces between particles and collectors. We investigated the origin and magnitude of opposing forces between silver and mica surfaces (representing nanosilver and sand grains) in solutions relevant to agricultural soils with direct measurements using a surface force apparatus. Solutions of variable NaNO3, Ca(NO3)2, and humic acid (HA) concentrations were used to differentiate individual contributing forces and quantify surface properties. The measured Hamaker constant for silver–water–mica was consistent with Lifshitz theory. Our results indicate that HA forms an adsorbed surface layer, but its charge, thicknesses, compressibility, and mass are significantly larger on mica than silver. Ca2+ primarily reduced the differences between the initially adsorbed HA layer properties on each surface, making them more similar. Force–distance profiles indicate that, when silver–mica systems were exposed to HA, osmotic–steric, electrostatic, and van der Waals forces dominate. Soft particle theory was deemed inappropriate for this system. Derjaguin's approximation was utilized to translate force measurements into interaction energy between nanosilver particles and mica collectors. We propose attachment efficiency estimates from measured surface properties, which suggest high particle mobility when nanosilver is applied to HA-rich agricultural soils with modest ionic strength.

22747. 题目: Role of Electrostatics in the Heterogeneous Interaction of Two-Dimensional Engineered MoS 2 Nanosheets and Natural Clay Colloids: Influence of pH and Natural Organic Matter
文章编号: N20111208
期刊: Environmental Science & Technology
作者: Indu Venu Sabaraya, Hyunjung Shin, Xintong Li, Rushmia Hoq, Jean Anne C. Incorvia, Mary Jo Kirisits, Navid B. Saleh
更新时间: 2020-11-12
摘要: Few-layered molybdenum disulfide (MoS2) nanosheets are poised to be at the core of low-voltage electronic device development. Upon environmental release, these two-dimensional (2D) structures can interact with abundant natural geocolloids. This study probes the role of dimensionality in modulating the aggregation behavior of 2D MoS2 nanosheets with plate-like geocolloids (i.e., homoionized kaolinite and montmorillonite clays). MoS2 nanosheets were exfoliated using an ethanol/water mixture, and aggregation kinetics were investigated with time-resolved dynamic light scattering at low monovalent salt concentrations and at three pH levels, in the presence and absence of Suwannee River humic acid (SRHA). Results indicate that pH and particle ratios are key to modulating the stability of MoS2/clay systems. At pH 4, aggregation of MoS2 increased with increasing MoS2/clay ratios and approached maximum values of 0.09 and 0.06 nm/s in the binary systems with montmorillonite and kaolinite, respectively. Electrostatic attraction facilitates heteroaggregation at pH values of 4 and 6; differences in the clay structures (i.e., face–face or face–edge aggregates) might explain the resulting MoS2/clay aggregate configurations, which were probed via the evolution of particle size distribution. The presence of only 0.1 mg/L SRHA drastically suppresses the heteroaggregation propensity of MoS2 nanosheets with geocolloids (to less than 0.01 nm/s at all pH values tested). The high stability of these heterogeneous systems under environmentally relevant conditions can increase the likelihood for cellular uptake and long-distance transport of MoS2.

22748. 题目: Unbound Natural Organic Matter Competes with Nanoparticles for Internalization Receptors During Cell Uptake
文章编号: N20111207
期刊: Environmental Science & Technology
作者: Ya-Tong Zhao, Shuai Yan, Bin Huang, Liuyan Yang, Hong-ming Ding, Ping Wang, Ai-Jun Miao
更新时间: 2020-11-12
摘要: Natural organic matter (NOM) that forms coronas on the surface of engineered nanoparticles (NPs) affects their stability, bio-uptake, and toxicity. After corona formation, a large amount of unbound NOM remains in the environment and their effects on organismal uptake of NPs remain unknown. Here, the effects of unbound NOM on the uptake of polyacrylate-coated hematite NPs (HemNPs) by the protozoan Tetrahymena thermophila were examined. HemNPs were well-dispersed without any detectable NOM adsorption. Kinetics experiments showed that unbound NOM decreased the uptake of HemNPs with greater inhibition at lower concentrations of the particles in the presence of NOM of higher molecular weight. The unbound NOM suppressed clathrin-mediated endocytosis but not the phagocytosis of HemNPs. Confirmation of these events was obtained using label-free hyperspectral stimulated Raman spectroscopy imaging and dissipative particle dynamics simulation. Overall, the present study demonstrates that unbound NOM can compete with HemNPs for internalization receptors on the surface of T. thermophila and inhibit particle uptake, highlighting the need to consider the direct effects of unbound NOM in bioapplication studies and in safety evaluations of NPs.

22749. 题目: Anaerobic Dehalogenation by Reduced Aqueous Biochars
文章编号: N20111206
期刊: Environmental Science & Technology
作者: Srinidhi Lokesh, Juhee Kim, Yuwei Zhou, Danping Wu, Bo Pan, Xilong Wang, Sebastian Behrens, Ching-Hua Huang, Yu Yang
更新时间: 2020-11-12
摘要: Dehalogenation is one of the most important reactions for eliminating trace organic pollutants in natural and engineering systems. This study investigated the dehalogenation of a model organohalogen compound, triclosan (TCS), by aqueous biochars (a-BCs) (<450 nm). We found that TCS can be anaerobically degraded by reduced a-BCs with a pseudo first-order degradation rate constant of 0.0011–0.011 h–1. The 288 h degradation fraction of TCS correlated significantly with the amount of a-BC-bound electrons (0.055 ± 0.00024 to 0.11 ± 0.0016 mol e–/mol C) available for donation after 24 h of pre-reduction by Shewanella putrefaciens CN32. Within the reduction period, the recovery of chlorine based on residual TCS and generated Cl– ranged from 73.6 to 85.2%, implying that a major fraction of TCS was fully dechlorinated, together with mass spectroscopic analysis of possible degradation byproducts. Least-squares numerical fitting, accounting for the reactions of hydroquinones/semiquinones in a-BCs with TCS and byproducts, can simulate the reaction kinetics well (R2 > 0.76) and suggest the first-step dechlorination as the rate-limiting step among the possible pathways. These results showcased that the reduced a-BCs can reductively degrade organohalogens with potential applications for wastewater treatment and groundwater remediation. While TCS was used as a model compound in this study, a-BC-based degradation can be likely applied to a range of redox-sensitive trace organic compounds.

22750. 题目: Production and functionality of exopolysaccharides in bacteria exposed to a toxic metal environment
文章编号: N20111205
期刊: Ecotoxicology and Environmental Safety
作者: Krishnamurthy Mathivanan, Jayaraman Uthaya Chandirika, Thangavel Mathimani, Rajendran Rajaram, Gurusamy Annadurai, Huaqun Yin
更新时间: 2020-11-12
摘要: In this study, the production and compositional analysis of exopolysaccharides produced by Bacillus cereus KMS3-1 grown in metal amended conditions were investigated. In addition, the metal adsorption efficacy of exopolysaccharides (EPS) produced by KMS3-1 strain was evaluated in a batch mode. Increased production of exopolysaccharides by KMS3-1 strain was observed while growing under metal amended conditions (100 mg/L) and also, the yield was in the order of Pb(II)>Cu(II)>Cd(II)>Control. Characterization of EPS using FT-IR, XRD, and SEM analysis revealed that the EPS can interact with metal ions through their functional groups (O‒H, CH, C˭O, C‒O, and C‒C˭O) and assist the detoxification process. Further, equilibrium results were fitted with the Langmuir model and notably, the maximum adsorption capacity (Qmax) of EPS for Cd(II), Cu(II), and Pb(II) found to be 54.05, 71.42, and 78.74 mg/g, respectively. To the best of our knowledge, EPS demonstrating proficient metal adsorption was substantiated by XRD analysis in this study. Owing to good adsorbing nature, the exopolysaccharides could be used as chelating substances for wastewater treatment.

22751. 题目: Does soluble starch improve the removal of Cr(VI) by nZVI loaded on biochar?
文章编号: N20111204
期刊: Ecotoxicology and Environmental Safety
作者: Chun Yang, Chazhong Ge, Xiaoliang Li, Lu Li, Bin Wang, Aijun Lin, Wenjie Yang
更新时间: 2020-11-12
摘要: A novel material that nano zero valent iron (nZVI) loaded on biochar with stable starch stabilization (nZVI/SS/BC) was synthesized and used for the removal of hexavalent chromium [Cr(VI)] in simulated wastewater. It was indicated that as the pyrolysis temperature of rice straw increased, the removal rate of Cr(VI) by nZVI/SS/BC first increased and then decreased. nZVI/SS/BC made from biochar pyrolyzed at 600 °C (nZVI/SS/BC600) had the highest removal efficiency and was suitable for a wide pH range (pH 2.1–10.0). The results showed that 99.67% of Cr(VI) was removed by nZVI/SS/BC600, an increase of 45.93% compared to the control group, which did not add soluble starch during synthesis. The pseudo-second-order model and the Langmuir model were more in line with reaction. The maximum adsorption capacity for Cr(VI) by nZVI/SS/BC600 was 122.86 mg·g−1. The properties of the material were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) mapping, Brunauer-Emmett-Teller (BET), Fourier-transform infrared (FTIR), and X-ray diffraction (XRD). The results showed that the nZVI particles were uniformly supported on the biochar, and the BET surface areas of nZVI/SS/BC was 40.4837 m2·g−1, an increase of 8.79 times compared with the control group. Mechanism studies showed that soluble starch reduced the formation of metal oxides, thereby improving the reducibility of the material, and co-precipitates were formed during the reaction. All results indicated that nZVI/SS/BC was a potential repair material that can effectively overcome the limitations of nZVI and achieve efficient and rapid repair of Cr(VI).

22752. 题目: Nitrogen and phosphorus additions accelerate decomposition of slow carbon pool and lower total soil organic carbon pool in alpine meadows
文章编号: N20111203
期刊: Land Degradation & Development
作者: Jin Hua Li, Bing Heng Cheng, Rui Zhang, Wen Jin Li, Xiao Ming Shi, Yong Wei Han, Lu Feng Ye, Nicholas J. Ostle, Richard D. Bardgett
更新时间: 2020-11-12
摘要: Nitrogen (N) and phosphorus (P) additions reduced soil organic carbon (SOC) contents and stocks in alpine meadows on the Tibetan Plateau. However, little is known about microbial mechanisms behind SOC decline. This study investigated the effects of long‐term N and P additions on microbial community composition and SOC decomposition (C mineralization (Cm), mean resistant times for active C pool (MRTa) and slow C pool (MRTs)) in alpine meadows. Results showed that total SOC pool was reduced by 2‐9% under N and P additions, of which slow C pool decreased by 3‐10% while active C pool increased by 4‐75% compared to the Control. N and P additions shortened MRTs by 34‐40% but prolonged MRTa by 30‐62%. The relative abundance of 4 bacterial families was related to Cm or MRTa while that of most of fungal families affected SOC decomposition (including Cm, MRTa and MRTs). N and P additions increased fungal diversity, differentially affected microbial community composition and structure through modifying microbial preference and increasing the abundance of microbes which are capable of decomposing complex carbohydrate. Soil pH, available N and total P were main factors determining microbial abundances. Microbial changes due to N and P additions accelerated decomposition of recalcitrant SOC, thus led to declines in slow C pool and total SOC pool but increases in active C pool. Therefore, long‐term N and P additions weaken soil functioning as C pool in alpine meadows. This article is protected by copyright. All rights reserved.

22753. 题目: Field Study and Reactive Simulation of Iron Migration in Groundwater during the Riverbank Filtration
文章编号: N20111201
期刊: Applied Geochemistry
作者: Ekaterina S. Kazak, Sergey P. Pozdniakov
更新时间: 2020-11-12
摘要: Water supply in Voronezh city, Russian Federation with the population more than 1,1 million people are based only on the groundwater of alluvial the Neogene-Quaternary (N-Q). Due to the riverbank filtration (RBF), the contaminated groundwater provinces with iron pollution formed in the alluvial aquifer. The high iron content in groundwater interferes its use for the Voronezh city's water supply. It may even bring about the inevitable water intakes abandonment due to problems with well clogging. We performed the series of field experiments (chemical tests of groundwater, spring, rain, reservoir and pore water, aquifer and bottom sediments) and numerical simulation to detect the potential iron source in pumped groundwater by riverbank water wells. We found that during the RBF, two contrary processes of Fe behaviour take place. On the one hand, the iron accumulation and transformation due to the iron hydroxides reduction by dissolved organic matter, occur in the bottom sediment. On the other hand, we observe the iron removal process from the bottom sediment due to Fe migration with attracted surface water along hydraulic pathways surface water - bottom sediments – aquifer – pumping wells. Finally, the mix of the attracted water with dissolved iron with natural Fe-free groundwater coming from the watershed forms the iron concentration pattern in pumping groundwater. The simulation results show that in the 3rd year of the RBF, the iron content reaches a maximum value in pumping groundwater and does not change for the operation time (25 years). Moreover, we have shown that during the long RBF, the iron pollution area will extend and even the northern and southern parts of the water intake facility will be contaminated by iron.

22754. 题目: Synthesis of magnetized nitrogen-doped biochar and its high efficiency for elimination of ciprofloxacin hydrochloride by activation of peroxymonosulfate
文章编号: N20111107
期刊: Separation and Purification Technology
作者: Yang You, Zhuanjun Zhao, Yiran Song, Jing Li, Jie Li, Xiuwen Cheng
更新时间: 2020-11-11
摘要: In this study, magnetized nitrogen-doped biochar (MNBC) was synthesized to degrade ciprofloxacin hydrochloride (CIP) as activator of peroxymonosulfate (PMS). Subsequently, several parameters were optimized to decompose CIP. Results showed that MNBC/PMS system displayed superior CIP removal efficiency and well stability. Its high degradation efficiency of CIP can reach 92.6% within 80 min, and its excellent magnetic properties is convenient for separation and recovery. Moreover, the dominant reactive oxide species roles were determined via EPR measurement method and radical capture experiments. In addition, the improved catalytic mechanism of MNBC/PMS system was proposed, which was ascribed to the generation of sulfate radicals and hydroxyl radicals. Meanwhile, the degradation pathways of CIP were illustrated. After four run utilization, the MNBC/PMS system still possessed 83% removal efficiency. Therefore, the synthesized MNBC magnetic carbon material might be a candidate to the removal of refractory pollutants in environmental remediation.

22755. 题目: Improvement of two-stage composting of green waste by addition of eggshell waste and rice husks
文章编号: N20111106
期刊: Bioresource Technology
作者: Wei Wang, Lu Zhang, Xiangyang Sun
更新时间: 2020-11-11
摘要: With the development of urban greening and increases in the human population, the production of green waste (GW) has been increasing in China. Although GW is biodegradable, its composting is difficult because of its low degradation rate. This study focuses on how addition of eggshell waste (ESW; at 0, 10, and 20%) and/or rice husks (RH; at 0, 15, and 25%) affects the two-stage composting of GW on the basis of temperature, bulk density, particle-size distribution, pH, nitrogen changes, carbon dioxide emission, organic matter degradation, humic substances, the activities of microorganisms and enzymes, and the phytotoxicity to germinating seeds. The combined addition of 10% ESW and 25% RH produced the highest quality compost in the shortest time. To produce a stable and mature product, two-stage composting of GW required 30 days without additives but only 20 days with the combined addition of 10% ESW and 25% RH.

22756. 题目: Deconvolution of post- and pre-salt petroleum sources in southeastern offshore Brazilian basins
文章编号: N20111105
期刊: Organic Geochemistry
作者: Thamara A. Barra, Clarisse L. Torres, Marco Aurélio Dal Sasso, Vinícius B. Pereira, Eugenio V. Santos Neto, Débora A. Azevedo
更新时间: 2020-11-11
摘要: The Campos, Santos and Espírito Santo Basins are part of the southeastern offshore Brazilian basins (SEOBB) where pre-salt reserves are located. This represents the most important oil province in Brazil. Constant growth in the discoveries and production of the country's oil reserves has shown the importance of the pre-salt discoveries; thus, proper oil constituent characterization at the molecular level is needed for this type of petroleum. Six oils, collected in pre- and post-salt reservoirs from SEOBB, were evaluated using GC-FID, GC-MS, GC-C-IRMS, GC×GC-TOFMS, and ESI(±)-Orbitrap HRMS. The biomarker parameters obtained indicated a lacustrine input for all the oils, except for the TAB-4G post-salt oil. All the oils reached the peak of the oil generation window, except the TAB-4G oil, which reached the late stage. The carbon isotope profiles suggested a lacustrine depositional environment for the organic matter (OM); the δ13C isotopic amplitudes ranged from 3.2‰ to 6.9‰. The profile of the TAB-4G oil suggested a contribution from terrestrial OM. This work is one of the first to apply ESI(±)-Orbitrap HRMS for geochemical characterization. In both (±) ionization modes, the data showed that the oils had high percentages of Nx classes, especially N1 compounds, strengthening the interpretation of a lacustrine origin for the OM. ESI(-) HRMS showed that the TAB-4G oil contained a high relative percentage of Ox classes, especially O1 with the 8–16 double bond equivalent (DBE) species, suggesting a marine contribution. The combination of the conventional geochemical approach with advanced chromatographic and mass spectrometric techniques allowed for a comprehensive molecular characterization of the post- and pre-salt oils, contributing to a better understanding of the prolific SEOBB petroleum systems.

22757. 题目: Assessing the impact of long-term soil phosphorus on N-transformation pathways using 15N labelling
文章编号: N20111104
期刊: Soil Biology and Biochemistry
作者: R.M. O'Neill, D.J. Krol, D. Wall, G.J. Lanigan, F. Renou-Wilson, K.G. Richards, A.B. Jansen-Willems, C. Müller
更新时间: 2020-11-11
摘要: A laboratory incubation study was conducted on a temperate grassland soil to quantify the main mineral nitrogen (N) transformation rates and pathways via a15N tracing approach. Soil samples were taken from a long-term phosphorus (P) trial to investigate the effects on gross N transformations under high and low phosphorus amendment. The soils were incubated over a 2-week period and treated with ammonium-nitrate (NH4NO3) which was applied to the soil both with and without a glucose amendment and labelled with 15N either on the ammonium (NH4+) or nitrate (NO3−) moiety at 50% atom enrichment. The results showed immobilisation to greatly outweigh mineralisation and that NO3− was predominantly produced via heterotrophic nitrification. Individual pathways for NO3− production were quantified including oxidation of NH4+, recalcitrant and labile organic N. Oxidation of labile organic N to NO3−, a newly considered pathway, accounted for between 63 and 83% of total NO3− production across the various treatments and P levels. This process was significantly higher in the low-P rather than the high-P soils (p < 0.05), highlighting the effect of soil P on the microbial community.

22758. 题目: Dissolved organic carbon loss from paddy fields by drainage and roles of common ions
文章编号: N20111103
期刊: Agriculture, Ecosystems & Environment
作者: Xiao Pu, Xue Dong, Hongguang Cheng, Jing Xie, Yuhu Zhang, Lu Lu, Yanjia Hu, Wenlong Song, Huan Xu
更新时间: 2020-11-11
摘要: Cations and anions exerted important effects on dissolved organic carbon (DOC) release and retention in arable soils. However, knowledge is limited on DOC loss from rice (Oryza sativa L.) paddies by drainage and its association with common ions under a conventional irrigation and drainage regime. This study aimed to investigate DOC dynamics in the soil-overlying water system and the synergistic behaviors of common ions (Na+, K+, Ca2+, Mg2+, Cl−, NO3− and SO42−) contributing to variations in DOC flux in drainage water at the pre-growing, vegetative and reproductive stages of rice cultivation in the Sanjiang Plain of NE China. Samples of overlying water and soil in three layers (0–20, 20–40, and 40–60 cm) were collected before drainage to evaluate variations of DOC and common ions across rice growing stages and to estimate DOC loss by drainage. Sorption experiments were conducted to determine DOC sorption capacities of surface soil (0–5 cm). Compared with the pre-growing stage, DOC concentrations in overlying water and soil significantly increased at the vegetative stage, while significant increases at the reproductive stage were merely in soil. Net movement of DOC was from soil to overlying water at the pre-growing and reproductive stages, and was close to equilibrium at the vegetative stage. Ca2+ and Mg2+ in surface soils (0–20 cm) displayed stronger capacities explaining DOC dynamics in the soil-overlying water system than the other common ions. As Ca2+ and Mg2+ in surface soils (0–20 cm) increased, DOC in the uppermost soil layers (0–20 and 20–40 cm) and overlying water increased, and DOC sorption capacities in surface soil were enhanced. DOC loss from paddy fields by drainage mainly occurred at the vegetative stage, occupying 62–83 % of the total, and much more attention ought to be paid to control drainage DOC loss during this period. In light of important roles of Ca2+ and Mg2+ in DOC dynamics and then DOC loss by drainage, appropriate measures with respect to addition of Ca2+ and Mg2+ could be taken into consideration in rice cultivation to alleviate paddy field DOC export.

22759. 题目: The role of soil in defining planetary boundaries and the safe operating space for humanity
文章编号: N20111102
期刊: Environment International
作者: Peter M. Kopittke, Neal W. Menzies, Ram C. Dalal, Brigid A. McKenna, Søren Husted, Peng Wang, Enzo Lombi
更新时间: 2020-11-11
摘要: We use soils to provide 98.8% of our food, but we must ensure that the pressure we place on soils to provide this food in the short-term does not inadvertently push the Earth into a less hospitable state in the long-term. Using the planetary boundaries framework, we show that soils are a master variable for regulating critical Earth-system processes. Indeed, of the seven Earth-systems that have been quantified, soils play a critical and substantial role in changing the Earth-systems in at least two, either directly or indirectly, as well as smaller contributions for a further three. For the biogeochemical flows Earth-system process, soils contribute 66% of the total anthropogenic change for nitrogen and 38% for phosphorus, whilst for the land-system change Earth-system process, soils indirectly contribute 80% of global anthropogenic change. Furthermore, perturbations of soils contribute directly to 21% of climate change, 25% to ocean acidification, and 25% to stratospheric ozone depletion. We argue that urgent interventions are required to greatly improve soil management, especially for those Earth-system processes where the planetary boundary has already been exceeded and where soils make an important contribution, with this being for biogeochemical flows (both nitrogen and phosphorus), for climate change, and for land-system change. Of particular importance, it is noted that the highly inefficient use of N fertilizers results in release of excess N into the broader environment, contributes to climate change, and results in release of ozone-depleting substances. Furthermore, the use of soils for agricultural production results not only in land-system change, but also in the loss (mineralization) of organic matter with a concomitant release of CO2 contributing to both climate change and ocean acidification. Thus, there is a need to markedly improve the efficiency of fertilizer applications and to intensify usage of our most fertile soils in order to allow the restoration of degraded soils and limit further areal expansion of agriculture. Understanding, and acting upon, the role of soils is critical in ensuring that planetary boundaries are not transgressed, with no other single variable playing such a strategic role across all of the planetary boundaries.

22760. 题目: Soil fungal mycelia have unexpectedly flexible stoichiometric C:N and C:P ratios
文章编号: N20111101
期刊: Ecology Letters
作者: Tessa Camenzind, Kay Philipp Grenz, Johannes Lehmann, Matthias C. Rillig
更新时间: 2020-11-11
摘要: Soil ecological stoichiometry provides powerful theories to integrate the complex interplay of element cycling and microbial communities into biogeochemical models. One essential assumption is that microbes maintain stable C:N:P (carbon:nitrogen:phosphorus) ratios independent of resource supply, although such homeostatic regulations have rarely been assessed in individual microorganisms. Here, we report an unexpected high flexibility in C:N and C:P values of saprobic fungi along nutrient supply gradients, overall ranging between 7‐126 and 20‐1488, respectively, questioning microbial homeostasis. Fungal N:P varied comparatively less due to simultaneous reductions in mycelial N and P contents. As a mechanism, internal recycling processes during mycelial growth and an overall reduced N and P uptake appear more relevant than element storage. The relationships among fungal stoichiometry and growth disappeared in more complex media. These findings affect our interpretation of stoichiometric imbalances among microbes and soils and are highly relevant for developing microbial soil organic carbon and nitrogen models.