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22721. 题目: Hydrological management constraints on the chemistry of dissolved organic matter in the Three Gorges Reservoir Reservoirs are well known as a far-reaching human modification on the functions of natural river networks. However, changes in the chemistry and reactivity of dissolved organic matter (DOM) responding to hydrological management for water retention structures, and its influence on the river carbon cycle, remain poorly understood. Here we show that hydrological management does shape the molecular composition of DOM in the world's largest Three Gorges Reservoir, as revealed by optical spectroscopy and ultrahigh-resolution mass spectrometry. Relatively higher terrestrial input, molecular complexity, isomeric complexity, and environmental stability of DOM were observed during the storage period, whereas the inverse occurred during the drainage period. The results demonstrate that the hydrodynamic processes, which are mainly controlled by water intrusion from mainstream to tributaries, are likely the underlying mechanism controlling DOM chemistry. Integrated with observations from worldwide river reservoirs, the DOM degradation experiments suggest that reservoir hydrological management would enhance DOM mineralization, thereby increase CO2 emission and change the river carbon cycle. | |||||
22722. 题目: THE DARK SIDE OF BLACK GOLD: Ecotoxicological aspects of biochar and biochar-amended soils Biochar, a product of biomass pyrolysis, is characterized by significant surface area, porosity, high water holding capacity, and environmental persistence. It is perceived as a material that can counteract climate change due to its high carbon stability and is also considered suitable for soil amendment (fertility improvement, soil remediation). However, biochar can have a toxic effect on organisms as harmful substances may be present in it. This paper reviews the literature regarding the current knowledge of harmful substances in biochar and their potential negative impact on organisms from different trophic levels. The effects of biochar on the content and toxicity of harmful substances in biochar-amended soils are also reviewed. Application of biochar into soil does not usually have a toxic effect and very often stimulate plants, bacteria activity and invertebrates. The effect however is strictly determined by type of biochar (especially the feedstock used and pyrolysis temperature) as well as contaminants content. The pH, electrical conductivity, polycyclic aromatic hydrocarbons as well as heavy metals are the main factor usually responsible for biochar toxicity. | |||||
22723. 题目: Constrained optimal foraging by marine bacterioplankton on particulate organic matter | |||||
22724. 题目: Win-win: application of sawdust-derived hydrochar in low fertility soil improves rice yield and reduces greenhouse gas emissions from agricultural ecosystems As a good soil synergist, biochar has a wide prospect in improving soil fertility and crop production. Although hydrochar, produced by hydrothermal carbonization process has attracted attention due to production advantages, hydrochar application in low fertility soils as well as its impact to the associated greenhouse gas (GHG) emissions in farmlands is rarely reported. To advance our understanding on the effect of hydrochar addition on grain yield from low fertility soils and the corresponding CH4 and N2O emissions, a soil-column experiment, with two hydrochar types (sawdust-derived hydrochar (SDH), microbial-aged hydrochar (A-SDH)) at two application rates (5‰, 15‰; (w/w)), was conducted. The results showed that hydrochar addition evidently increased rice yield. The N2O emissions were mainly related to the substrate supply of the hydrochar itself and less affected by the denitrifiers (functional genes) present. Hydrochar amendment at low application rate (5‰; SDH05, A-SDH05) significantly decreased the cumulative N2O emissions by 26.32%~36.84%. Additionally, hydrochar amendment could not increase the CH4 emissions due to the substrate limitation; the cumulative emissions were similar with those from the control, ranging between 11.1~12.8 g m-2. Regarding grain yield and global warming potential, greenhouse gas intensity from the soils subjected to hydrochar (SDH05, A-SDH05, A-SDH15) were significantly lower than that of the control, observation attributed to the high yield and low N2O emissions. Overall, hydrochar addition is an effective strategy to ensure grain yield in low fertility soils with relatively low/controlled GHG emissions, especially when the amendment is applied at low application rate. | |||||
22725. 题目: Factors governing soil water repellency under tillage management: the role of pore structure and hydrophobic substances Soil water repellency (SWR) has significant effects on soil degradation by changing some soil processes (e.g. carbon sequestration and soil erosion). Understanding the influence factors of SWR under conservation agriculture are playing a vital role in the sustainable development for improving soil quality. However, how soil pore structure influence on SWR remains unclear. We aim to assess the impact of hydrophobic substances and pore structure on SWR. Here we conducted two long‐term experimental fields with three treatments: conventional tillage (CT), reduced tillage (RT), and no‐tillage (NT). X‐ray tomography and the sorptivity method were used to measure soil pore structure and SWR, respectively. We found that soil organic carbon (SOC) and microbial biomass carbon (MBC) were higher in RT and NT treatments than in CT. MBC had significant influences on soil water sorptivity (Sw) and water repellency index (RI) (P < 0.001), whereas SOC had no influence on Sw (P > 0.05). MBC also showed a closer relationship with SWR than SOC in redundancy analysis. The RT and NT increased the porosity of 55–165 μm that had a positive relationship with ethanol sorptivity and RI (P < 0.05). Ethanol sorptivity increased with an increase in soil pore porosity and connectivity under RT and NT treatments. However, increasing the pore surface area could decrease Sw due to enhance contact area between hydrophobic substances and soil water. Overall, the RT and NT treatments increased the water repellency index, which was a result of the interactions between pore structure and hydrophobic substances. This article is protected by copyright. All rights reserved. | |||||
22726. 题目: Controls on organic matter enrichment in source rocks of the Shahejie Formation in the southwestern Bozhong Sag, Bohai Bay Basin, China With the discovery of the Bozhong 19–6 large gas field in the Bohai Bay Basin, the study of lacustrine source rocks in the southwestern Bozhong Sag has garnered new interest. In this paper, 107 source rock samples of the Paleogene Shahejie Formation (Es) from the southwestern Bozhong Sag were analyzed with organic and inorganic methods and compared with other sags in the Bohai Bay Basin to reveal the depositional environment and controlling factors of organic matter enrichment during the deposition of the Es. The formation of source rocks (average total organic content = 2.76%) was subject to a combination of high organic productivity and enhanced organic preservation. Also, this was reflected by the existence of nutrient elements of P and Ba as well as other high productivity-related elements such as Cu, Zn, and Ni. The moderate Mo enrichment factor, Pr/Ph and low to moderate (C/P)org ratios were an essential part of this organic preservation. Moreover, the evidence we observed for the existence of hydrothermal activities consisted of high contents of quartz and pyrite, large positive Eu anomalies, and enrichment of elements related to hydrothermal fluids. Hydrothermal influence may lead to similarities and fluctuations in water salinity, organic productivity and preservation in the third (Es3) and first (Es1) members of the Es. Hydrothermal fluids may play an essential role in promoting the development of high organic productivity, stable reducing environment, and brackish water (as shown by the range of B/Ga and TS/TOC) in the lakes during the source rock deposition. This paper may provide implications for gas accumulation mechanisms and a complete set of organic and inorganic experimental data for source rock analysis in other lacustrine rift basins. | |||||
22727. 题目: Environmental response to volcanic activity and its effect on organic matter enrichment in the Permian Lucaogou Formation of the Malang Sag, Santanghu Basin, Northwest China Lacustrine organic-rich fine-grained rocks are widespread in the second member of the Permian Lucaogou Formation (P2l2) in the Malang Sag, Santanghu Basin, with complex lithology and significant changes of lithofacies due to frequent volcanic activity. In this study, the mineralogical and petrological characteristics, types of organic matter (OM), and effect of volcanism on the sedimentary environment and OM accumulation were analyzed using organic, carbon, and oxygen isotopes, as well as major and trace element data. The results revealed that the P2l2 was characterized by mixed deposition of volcanic ash and carbonate minerals, with four main rock types: tuff, dolomitic tuff, tuffaceous dolomite, and dolomite. The fine-grained rocks dominantly contain type I and II1 kerogens, which were in a low-mature stage and exhibited excellent original hydrocarbon generative potential. When volcanic activity was strong, large amounts of nutrients were released by the volcanic ash, which then entered the lake, in turn promoting the blooming of phytoplankton, and causing the δ13C values in the tuff to decrease. In addition, the paleotemperature decreased for a short time, and the suboxic-euxinic environment was conducive to the preservation of OM, resulting in high total organic carbon (TOC) content in the tuff. In contrast, during intermittent or weak periods of volcanic activity, the climate was hotter and drier, and evaporation resulted in a sustained increase of salinity. Consequently, the growth of algae was restricted, which brought about an increase in the δ13C values and relatively low TOC content in the dolomite. The relationships among primary productivity, redox conditions, clastic influx proxies, and TOC content illustrate that primary productivity was the most vital control on the accumulation of OM. High primary productivity was mainly driven by volcanic ash falls. Meanwhile, high salinity and suboxic-euxinic conditions were beneficial to the preservation of OM, giving rise to a high degree of OM enrichment. | |||||
22728. 题目: Dissecting microbial community structure and metabolic activities at an oceanic deep chlorophyll maximum layer by size-fractionated metaproteomics The deep chlorophyll maximum (DCM), a critical layer in the ocean characterized by the highest biomass and productivity, determines marine productivity, biogeochemical cycling and carbon sequestration. However, a comprehensive understanding of microbial community structure and metabolic activities in this layer is lacking in several parts of the oceans. Here, we characterized the whole spectrum of proteins covering three size fractions (0.7-200 µm, 0.2-0.7 µm, 10 kDa-0.2 µm) in the DCM of the South China Sea using a metaproteomic approach. A total of 17 724 non-redundant proteins were confidently identified. Proteins from Cyanobacteria, SAR11, nitrite-oxidizer bacteria, Archaea, eukaryotic phytoplankton and phototroph-associated viruses were abundant. These organisms were actively involved in diverse biogeochemical processes including light-dependent energy transduction, carbon fixation, nitrification, sulfur metabolism, dissolved organic matter (DOM) uptake, and C1 and methylated compounds oxidation. Furthermore, chemolithoautotrophic activity of Nitrospinae and Thaumarchaea complemented carbon fixation pathways in this habitat. Notably, photoheterotrophic activity of SAR11 and PVC (Planctomycetes, Verrucomicrobia and Chlamydiae) bacteria and mixotrophic activity of photoautotrophs suggested diverse regulation channels of light on microbe-mediated DOM recycling. This in-depth metaproteomic study provides a holistic view of microbial community and metabolic activities in the DCM, and uncovers novel biogeochemical processes, especially those previously ignored but potentially active in the smallest fraction. | |||||
22729. 题目: Cumulative effects of pyrolysis temperature and process on properties, chemical speciation, and environmental risks of heavy metals in magnetic biochar derived from coagulation-flocculation sludge of swine wastewater Coagulation-flocculation sludge (CFS) of swine wastewater was pyrolyzed at 400 °C – 700 °C to produce magnetic biochar (MBC) under anaerobic (MBCN) and hypoxic (MBCA) environments in order to investigate the characteristics and risks of heavy metals (HMs) in the MBC. Magnetite dominated the crystal phase of the MBCs obtained at 400 °C to 600 °C. Two forms of zero valent Fe were observed in the MBCs obtained at 700 °C, while γ-Fe was dominant in MBCA700 and α-Fe was dominant in MBCN700. Owing to the high concentration of chloride in the sludge, metal chlorides generated by chlorination lowered the pH of the MBCs compared to that of the CFS, except for MBCN700 because of Fe-C micro-electrolysis. The unstable fractions of some HMs, such as Zn, Cu, Ni, and Mn, increased when the increasing temperature from 400 °C to 700 °C as metal chlorides formed. The percentages of the acid-soluble and exchangeable became zero in MBC700 because HMs (except for Mn) could be adsorbed by ferric hydroxide colloid during the extraction. The lowest risk assessment code values were obtained in MBC700, except for the case of Mn. Compared with the CFS, the potential risk of HMs in the MBCs was significantly reduced, and MBCA600 presented the lowest environmental risk. This work demonstrates that pyrolysis is a promising and cost-effective method for the safe disposal of HM-polluted CFS and production of MBCs. | |||||
22730. 题目: Ultrasound assisted adsorption of reactive dye-145 by biochars from marine Chlorella sp. extracted solid waste pyrolyzed at various temperatures Algal biomass extraction for biodiesel production generates a considerable amount of solid waste known as extracted residue, which requires proper handling. This work aimed to produce biochar from the extracted marine Chlorella sp. solid waste (EMCSW) at 450, 550 and 650 °C. The biochar yield, physiochemical characterization and potential application in ultrasound assisted adsorption of reactive yellow dye-145 (RYD-145) were investigated. The biochar mass yield decreased from 45 to 34 % with temperature increase from 450 to 650 °C. Reduction of C, H, N, S and O and increased ash were observed with the temperature increase. The biochars were alkaline in nature having negative surface charges and porous structure with OH surface functional groups and Mg, Al, K and P minerals, making them suitable candidate adsorbents. The largest 351 m2/g specific surface was observed for the biochar produced at 550 °C. Ultrasound assisted adsorption of RYD-145 by BC-550 was highly efficient (99 %) in 1 min. The adsorption experimental data matched well the Freundlich and the pseudo-second order models. The EMCSW was demonstrated to be a valuable feedstock for biochar production, to be used as a cost-effective and highly efficient adsorbent. | |||||
22731. 题目: Treatment of effluents containing 2-chlorophenol by adsorption onto chemically and physically activated biochars The application of adsorption using biochars for the remediation of effluents containing emerging contaminants, including chlorophenols, is a hotspot and trend development in the literature. This treatment is more interesting when using readily available wastes and at no cost, such as malt bagasse, for example. Here, the biochars were produced from malt bagasse, by physical and chemical activation (with CO2 and ZnCl2, respectively) and employed as adsorbents in the remediation of effluents containing 2-chlorophenol. Results revealed that the activated biochars have mesoporous structures and surface areas of 161 m² g−1 (CO2) and 545 m² g−1 (ZnCl2). For both activated biochars, adsorption of 2-chlorophenol was favored under acid conditions, with the highest adsorption capacities found using ZnCl2-activated biochar. The maximum adsorption capacity using ZnCl2-activated biochar was 150 mg g−1. The process was endothermic and spontaneous. ZnCl2-activated biochar exhibited an efficiency of 98 % (using a dosage of 10 g L−1) in the treatment of industrial effluents containing 2-chlorophenol. | |||||
22732. 题目: Unexpected biomass burning aerosol absorption enhancement explained by black carbon mixing state Direct and semi‐direct radiative effects of biomass burning aerosols (BBA) from southern and central African fires are still widely debated, in particular because climate models have been unsuccessful in reproducing the low single scattering albedo in BBA over the eastern Atlantic Ocean. Using state‐of‐the‐art airborne in‐situ measurements and Mie scattering simulations, we demonstrate that low single scattering albedo in well‐aged BBA plumes over southern West Africa results from the presence of strongly absorbing refractory black carbon (rBC), whereas the brown carbon contribution to the BBA absorption is negligible. Coatings enhance light absorption by rBC‐containing particles by up to 210%. Our results show that accounting for the diversity in black carbon mixing state by combining internal and external configurations is needed to accurately estimate the optical properties, and henceforth the shortwave direct radiative effect and heating rate of BBA over southern West Africa. | |||||
22733. 题目: Glacier loss impacts riverine organic carbon transport to the ocean Lateral transport of organic carbon (OC) to the coastal ocean is an important component of the global carbon cycle because rivers transport, mineralize, and bury significant amounts of OC. Glaciers drive water and sediment export from many high‐elevation and high‐latitude ecosystems, yet their role in watershed OC balances is poorly understood, particularly with regard to particulate OC. Here we evaluate seasonal water, sediment, and comprehensive OC budgets, including both dissolved and particulate forms, for three watersheds in southeast Alaska that vary in glacier coverage. We show that glacier loss will shift the dominant size fraction of riverine OC from particulate toward dissolved and potentially alter the provenance of particulate OC. Glacier coverage also controls whether OC export is source (C stock) or transport (runoff) limited at the watershed scale. These findings provide insight into the future trajectory of OC export in glacierized regions. | |||||
22734. 题目: Errors induced by spectral measurement positions and instrument noise in soil organic carbon prediction using vis-NIR on intact soil Soil spectroscopy potentially would become a routine method for the measurement of soil properties in the field on soil cores. However, many factors could lead to errors in the measurement of spectra from intact soil cores. So far, errors induced by spectral measurement positions and instrument noise have rarely been quantified. The present study evaluated these errors based on 160 intact ring core samples collected from 20 profiles in a forest, southwest China. Each ring sample was scanned using a visible near-infrared (vis-NIR) spectrometer at nine evenly distributed positions at both ends of the ring to characterize within-sample variability. In addition, 10 scans were made at each position to characterize instrument error. A position spectrum was then calculated by averaging the 10 scans at each position, while a sample spectrum was calculated by averaging all 180 scans of each sample. The samples were then tested for soil organic carbon (SOC) content using the wet oxidation method. Based on the sample spectra and SOC content, a partial least squares regression (PLSR) model was calibrated. The modeling error was empirically calculated. Each scan, position spectrum, and sample spectrum was then fed into the calibrated PLSR model to predict SOC content, and the prediction results were evaluated for errors induced by instrument noise and different spectral measurement positions. Results showed that the error induced by different spectral measurement positions was about 75% of the modeling error, while the error induced by instrument noise was small and negligible. These three errors in terms of standard error of prediction (SEP) accounted for 18.6%, 23.8% and 1.46% of the average measured SOC content of the samples, respectively. Besides, the error due to different soil core sampling positions was also considerable. In terms of SEP, this error accounted for 12.5% of the average measured SOC content. These quantified error budgets would help to account for uncertainty in the measurement of soil properties using spectroscopy in the field. | |||||
22735. 题目: Rapid PXRF soil organic carbon and organic matter assessment using novel modular radiation detector assembly Soil organic matter and organic carbon are variables of critical environmental importance in terms of soil productivity and function, global food security, and climate change mitigation. Rapid and accurate assessment of these variables is central to national programs and international agreements. Portable X-ray fluorescence instruments are widely used to rapidly quantify and map soil elements, however quantification of light elements that constitute the majority of organic materials is not yet possible with this technique (e.g. carbon). We developed a novel attachment for portable X-ray fluorescence instrumentation enabling concurrent volumetric soil organic matter and organic carbon quantification during PXRF analyses. This primary prototype outperformed more expensive visible-near infrared instrumentation using parsimonious soil specific simple linear regression (R2 ranged 0.85–0.97) enabling rapid, parallel, nondestructive, cost-effective acquisition of soil elemental concentrations together with soil organic carbon and soil organic matter data. | |||||
22736. 题目: The multi-disciplinary study of Early Copper Age lamps from Zgornje Radvanje (NE Slovenia) This paper focuses on the analysis and identification of two prehistoric lamps from Zgornje Radvanje (NE Slovenia). The analysis of the organic residues and experimental archaeology allowed us to characterize the fuel source and the wick remains of oval-formed ceramic artefacts from the Copper Age settlement. Infrared spectroscopy (ATR IR), GC-MS and GC-C-IRMS were used to study organic compounds in two archaeological samples, with comparative composition data yielding experiments with modern wicks, linseed oil and animal fats. ATR IR showed traces of plant fibres in the sample of charred residues from one of the lamps. A comparably higher frequency of straight-chain compounds with odd numbers of carbon atoms provided the extracted lipids from the ceramics of the second oval-formed ceramic artefact. We interpret these to mean that carbonised organic residues from the inner surface of the ceramic object are the result of smouldering, with the identified residues of plant fibres probably associated with the remnants of the wick. The GC-MS analysis showed a higher frequency of straight-chain compounds with odd numbers of carbon atoms (especially C15:0 fatty acids) together with two double bond positional isomers of C18:1 in the second oval-formed artefact. The presence of C18:2 and C18:3 fatty acids that are typical for linseed oils was also detected. These analysis together with GC-C-IRMS analysis suggest a predominant use of ruminant fat as fuel for lighting possibly in combination with plant oils. Burns similar to those on the original artefact were observed on replicas of the artefact after they were used as lamps. | |||||
22737. 题目: Identifying recent sources and fate of sedimentary nitrogen in the Baltic Sea based on organic matter elemental composition and nitrogen and carbon stable isotopes ratios Sedimentary nitrogen (SN) provenience and fate in surface and subsurface sediments collected from the Baltic Sea were assessed. SN and sedimentary organic carbon (SOC) concentrations, stable isotopic signatures (δ15NSN and δ13CSOC) and SOC/SN molar ratios, were determined in subsequent layers of twenty-four sediment cores dated with 210Pb/137Cs and fifty-seven surface sediments. Sedimentation rates in the range 66–736 g/m2yr−1 (0.05–0.34 cm/year) were measured. Prolonged incubation of sediments in the laboratory led to a 17–37% decrease of SN in surface sediments, and no SN loss in sediments deposited before 1940. Decrease of δ15NSN on incubation (1‰ on average), and gradients of δ15NSN, between recent - surface (3.5‰) vs. 100 years old - subsurface (2.1‰) sediments were attributed to varying contributions of labile nitrogen to the SN pool. Annual deposition of SN to sediment surface and burial in subsurface sediments amounted, respectively, to 5 ± 2 g/m2 and 3.5 ± 1 g/m2. | |||||
22738. 题目: Sedimentary organic matter composition from tropical ports with distinct geographic and morpho-hydrodynamic characteristics: Evaluation through multiple biochemical markers Increasing coastal urbanization and shipping activity-related environmental pollution advocate the importance of assessment of port ecosystems. Fatty acid biomarkers, elemental components, and biopolymers were used to evaluate the composition of sedimentary organic matter and benthic trophic status of Kolkata (freshwater, enclosed docks) and Kandla (seawater, macrotidal) ports of India. The sediment fatty acid composition indicated relatively fresh and energy-rich organic matter of phytoplankton and bacterial origin inside Kolkata port than the outside riverine station and Kandla port. Biopolymeric carbon (BPC), used as an indicator of trophic status, revealed eutrophic condition in Kolkata port with high accumulation of organic matter of autochthonous origin, attributed to poor water flushing and input of anthropogenic wastes. In contrast, Kandla port was meso-oligotrophic, rich in bacteria, and terrestrial plant-derived materials. Such an assessment of ports' trophic status helps to evaluate the health of the ecosystem and in management practices. | |||||
22739. 题目: Soil organic carbon controls dissimilatory nitrate reduction to ammonium along a freshwater-oligohaline gradient of Min River Estuary, Southeast China Quality and source of soil organic carbon controlling DNRA in estuarine wetlands have not been well understood. We used a 15N isotopic tracer approach to investigate DNRA rates and determined the effects of organic carbon quality and source on magnitudes and distribution of DNRA along a freshwater-oligohaline gradient of Min River estuary, Southeast China. DNRA rates ranged from 0.45 to 2.92 nmol g−1 h−1 and were significantly higher in summer than in winter. DNRA was well predicted by dissolved organic carbon (DOC), organic carbon isotope (δ13Corg), total OC as the main predictor variables, which explained 63%, 6.0% and 7.0% of DNRA variances, respectively. Water content and temperature were crucial for DOC availability with important implications on DNRA. Soil δ13Corg increased from freshwater to oligohaline wetlands and showed a positive correlation with DNRA. We therefore conclude that high DOC availability enhances DNRA and can best predict spatial distribution in subtropical estuary. | |||||
22740. 题目: Effects of straw biochar application on soil temperature, available nitrogen and growth of corn Straw biochar could improve the water holding capacity effectivity of salinized soil, increase soil fertili, enhance crop yield, reduce greenhouse gas emission, and mitigate climate change. The mechanism of using straw biochar for soil improvement is different under various climate and soil texture conditions. To explore the mechanism of using straw biochar to improve soil and its influence on crop yield in the typical arid and semi-arid, a large temperature difference between day and night, soil temperature at different depths, and physiological changes and crop yield of maize at different growth stages were studied. It is assumed that straw biochar can improve the properties of salinized soil including physicochemical indexes, and crop physiological index, stimulates the positive circulation between soil, vegetation, and microorganisms, and plays a role in improving soil quality. The results showed that biochar application increased the average soil temperature (T) by 2 °C and reduced day-night T differences. Application of 30 t/ha biochar increased the average maize leaf T by 2.2 °C and photosynthetic rate by 16.5%. Furthermore, the average transpiration rate doubled compared to control, and the chlorophyll value increased by 21%. The application of biochar improved the utilization rate of nitrogen fertilizer by enhancing ammonification. Biochar application caused a maximum overall yield increase of 11.9% compared to control treatment (CK). Therefore, these results provide a practical basis for improving weakly alkaline farmland soils in arid and semi-arid areas, and provide an effective method to potentially mitigate the environmental crisis and promote sustainable development in agriculture. | |||||
