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23621. 题目: Innovative spherical biochar for pharmaceutical removal from water: Insight into adsorption mechanism
文章编号: N20020903
期刊: Journal of Hazardous Materials
作者: Hai Nguyen Tran, Fatma Tomul, Ha Thi Hoang Nguyen, Dong Thanh Nguyen, Eder C. Lima, Giang Truong Le, Chang-Tang Chang, Vhahangwele Masindi, Seung Han Woo
更新时间: 2020-02-09
摘要: In this study, we developed innovative biochars with high porosity and excellent paracetamol (PRC) adsorption capacity. The optimal pyrolysis temperatures of spherical biochar (derived from pure glucose) and non-spherical biochar (from pomelo peel wastes) were obtained at 900 °C and 700 °C, respectively. Various advanced techniques were applied to characterize the prepared biochars. Spherical and non-spherical biochars exhibited large specific surface area (1292 and 1033 m²/g) and high total pore volume (0.704 and 1.074 cm³/g), respectively. The adsorption behavior of PRC onto two biochars was conducted utilizing batch experiments. Results demonstrated that the adsorption process was slightly affected by the change of solution pH (2–11) and addition of NaCl (0.05–1.0 M) and was able to achieve fast equilibrium (∼120 min). The maximum adsorption capacity of spherical biochar (286 mg/g) for PRC was approximately double that of non-spherical biochar (147 mg/g). The signal of thermodynamic parameters was negative ΔG° and ΔH° values, but positive ΔS° value. The adsorption mechanism consisted of pore-filling, hydrogen bonding formations, n-π and π-π interactions, and van der Waals force. The adsorption capacities of two biochar were insignificantly dependent on different real water samples containing PRC. Consequently, the biochars can serve as a green and promising material for efficiently removing PRC from water.
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23622. 题目: Microbial extracellular polysaccharide production and aggregate stability controlled by switchgrass (Panicum virgatum) root biomass and soil water potential
文章编号: N20020902
期刊: Soil Biology and Biochemistry
作者: Yonatan Sher, Nameer R. Baker, Don Herman, Christina Fossum, Lauren Hale, Xing-Xu Zhang, Erin Nuccio, Malay Saha, Jizhong Zhou, Jennifer Pett-Ridge, Mary Firestone
更新时间: 2020-02-09
摘要: Deep-rooting perennial grasses are promising feedstocks for biofuel production, especially in marginal soils lacking organic material, nutrients, and/or that experience significant water stress. Perennial grass roots influence surrounding soil conditions and microbial activities, and produce extracellular polymeric substances (EPS) composed primarily of extracellular polysaccharides (EPSac). These polymers can alleviate microbial moisture and nutrient stress, and enhance soil characteristics through improved water retention and aggregate stability—which may in turn enhance carbon persistence. In this study we used a ¹³CO₂ greenhouse tracer experiment to examine the effect of switchgrass cultivation on EPSac production and origin in a marginal soil with five fertilization/water treatments (control, +N, +NP, +P, low water), and compared these results with measurements of field soils collected after long-term switchgrass cultivation. Soils with added nitrogen and phosphorus (+NP) had the highest root biomass, EPSac and percentage of water-stable soil aggregates. Multiple linear regression analyses revealed that root biomass and soil water potential were important determinants of soil EPSac production, potentially by controlling carbon supply and diurnal changes in moisture stress. Path analysis showed that soil aggregation was positively correlated with bulk soil EPSac content and also regulated by soil water potential. High mannose content indicated the majority of EPSac was of microbial origin and ¹³CO₂ labeling indicated that 0.18% of newly fixed plant carbon was incorporated into EPSac. Analysis of field soils suggests that EPSac is significantly enhanced after long-term switchgrass cultivation. Taken as a whole, our greenhouse and field results demonstrate that switchgrass cultivation can promote microbial production of EPSac, providing a mechanism to enhance aggregation in marginal soils.

23623. 题目: Converting industrial waste cork to biochar as Cu (II) adsorbent via slow pyrolysis
文章编号: N20020901
期刊: Waste Management
作者: Qihang Wang, Zongyuan Lai, Jun Mu, Demiao Chu, Xiaorong Zang
更新时间: 2020-02-09
摘要: Cork is light, porous, carbon-rich, and renewable, which leads to competitive advantages in the preparation of biochar, as compared to other biomass material. In this work, we propose to convert cork powder into cork-based biochar as Cu (II) adsorbent via slow pyrolysis, thereby providing a reliable and simple method for recycling cork industrial waste. The physicochemical properties of cork-based biochar prepared under different pyrolysis temperatures (450, 550, 650, and 750 °C) and pyrolysis time (0.5, 1.0, 1.5, and 2.0 h) were characterized by elemental analysis, FT-IR, XRD, N₂ adsorption and SEM. The adsorption capacity of cork-based biochar on heavy metal ions was further evaluated by Cu ion adsorption testing. Results showed that the cork-based biochar produced under conditions of higher pyrolysis temperature and time, has higher aromaticity and lower polarity, larger specific surface area, and enhanced Cu ion adsorption capacity. The maximum specific surface area of cork-based biochar prepared at 750 °C for 0.5 h was 392.5 m²/g, which surpasses most other biochars reported in previous studies, which are beneficial to the application of wastewater management. The SEM image demonstrated that the biochar retains the special hollow polyhedral cell structure of raw material cork. Furthermore, a large number of pores formed on the cell wall after high temperature pyrolysis, and the cells are connected with each other through these open pores. Finally, cork-based biochar exhibits superior Cu ion adsorption capacity (18.5 mg/g) with a shorter equilibrium time (4 h), which gives it a competitive advantage to similar adsorbents.
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23624. 题目: Land-use controls on nutrient loads in aquifers draining agricultural and mixed-use karstic watersheds
文章编号: N20020808
期刊: Environmental Monitoring and Assessment
作者: G. V. Tagne, C. Dowling
更新时间: 2020-02-08
摘要: Agricultural nonpoint source pollution from the upper areas of the Upper Mississippi, Missouri, and Ohio River basins accounts for the majority of the excess nitrogen that leads to the Gulf of Mexico’s hypoxic zone. However, agriculture landscapes across the USA, Europe, and China are undergoing major changes related to the proliferation of confined animal feeding operations (CAFOs) that account for a greater proportion of point source contamination. Mitigating long-term nutrient inputs at a large scale (Mississippi River Basin) requires understanding these microscale changes at the small watershed level (less than 100 km²). To assess the control of land-use and subsurface hydrological processes on nutrient fate and transport, temporal patterns in nutrient concentrations in a mixed land-use karstic watershed were analyzed. To assess the control of differential land-use sources on total inorganic nitrogen (TIN) loads within the watershed, 4 months of weekly water sampling was performed at a spring location and at two underground conduit locations. The observed temporal variations in nutrient concentrations are primarily associated with seasonal changes in land-use associated with corn growth. Data show that land-use sources explain much of the temporal variability of TIN at the spring when weighted against the hydrological factor. End-member-mixing analysis of dissolved organic carbon (DOC) shows a progressive increase in the contribution of DOC-enriched sources and a more labile form of carbon toward the harvest time. Overall, during high flow, nonpoint source infiltration from manure-fertilized croplands in the northern branch (NB) dominate DOC loads. Because conduit-dominated karstic aquifers are more susceptible to contamination from direct and fast (< 7 h) subsurface infiltration during late summer rainfall period (July to August), a slight advance in the timing of manure application could substantially reduce nutrient loads to local groundwater. A combined evaluation of subsurface hydrological processes and land-use factors controlling nutrients at the scale of small watersheds is crucial to developing site-specific nutrient management plans and managing the Gulf of Mexico’s hypoxic zone.

23625. 题目: Heterogeneous Fenton oxidation of trichloroethylene catalyzed by sewage sludge biochar: Experimental study and life cycle assessment
文章编号: N20020807
期刊: Chemosphere
作者: Yu-Fong Huang, Yu-Yang Huang, Pei-Te Chiueh, Shang-Lien Lo
更新时间: 2020-02-08
摘要: Heterogeneous Fenton oxidation of trichloroethylene (TCE) catalyzed by sewage sludge biochar was studied. The highest TCE removal efficiency was 83% at pH 3.1, catalyzed by 300 W biochar. The biochars produced at higher microwave power levels provided better catalytic effect, due to higher iron contents and specific surface areas. Reactivity of sewage sludge biochar maintained after several uses, which provides an advantage for using as a permeable reactive barrier to remediate groundwater pollution. Chromium, copper, nickel, lead, and zinc were found in the leachate generated from sewage sludge biochar, and most of the concentrations were lower than the standards for non-drinking water use. Besides, copper, zinc, and iron were found in the reaction solutions of Fenton oxidation. Because of the highest dosage required for Fenton oxidation, the environmental impact caused by 200 W biochar is highest. The environmental impact caused by 300 W biochar is lowest. Among the four endpoint impact categories in the life cycle assessment (LCA), human health is the highest concern, whereas ecosystem quality is the least. According to experimental and LCA results, the optimum microwave power level would be 300 W. The primary impact source is microwave pyrolysis because of high energy usage.
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23626. 题目: Microalgae carbon fixation integrated with organic matters recycling from soybean wastewater: Effect of pH on the performance of hybrid system
文章编号: N20020806
期刊: Chemosphere
作者: Chunfeng Song, Xiaoxuan Han, Yiting Qiu, Zhengzheng Liu, Shuhong Li, Yutaka Kitamura
更新时间: 2020-02-08
摘要: Microalgae have been considered as promising alternative for CO₂ fixation and wastewater purification. In our previous work, a hybrid microalgae CO₂ fixation concept has been put forward, which initially used carbonate solution absorb CO₂, and then provided obtained bicarbonate as nutrition for microalgae growth to avoid the challenge of low CO₂ solubility and carbon fixation efficiency in the conventional process. In this work, the proposed hybrid system was further intensified via integrating soybean wastewater nutrition removal with bicarbonate-carbon (NH₄HCO₃ and KHCO₃) conversion. The investigation results indicated that the maximum biomass productivity (0.74 g L⁻¹) and carbon bioconversion efficiency (46.9%) were achieved in low-NH₄HCO₃ concentration system with pH adjusted to 7. pH adjustment of different bicarbonate systems also enhanced total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD) removal efficiency up to 87.5%, 99.5% and 77.6%, respectively. In addition, maximum neutral lipid (14.4 mg L⁻¹·d⁻¹) and polysaccharide (14.5 mg L⁻¹·d⁻¹) productivities could be obtained in the KHCO₃ systems, while higher crude protein productivity (48.1 mg L⁻¹·d⁻¹) was yielded in the NH₄HCO₃ systems.
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23627. 题目: Drivers of benthic extinction during the early Toarcian (Early Jurassic) at the northern Gondwana paleomargin: Implications for paleoceanographic conditions
文章编号: N20020805
期刊: Earth-Science Reviews
作者: Wolfgang Ruebsam, Matías Reolid, Abbas Marok, Lorenz Schwark
更新时间: 2020-02-08
摘要: During the early Toarcian multiple environmental perturbations led to the genesis of the Toarcian Oceanic Anoxic Event (T-OAE), expressed by the widespread occurrence of black shales that were formed under oxygen-deficient conditions. Factors promoting organic matter preservation also drove benthic extinction due to low aqueous O₂ levels and habitats poisoned by H₂S. However, the development of benthic barren intervals in oxygenated shelf areas, lacking black shales, indicates that even in these areas benthic communities experienced a crisis. To understand environmental changes and to determine factors driving benthic extinction we applied paleontological and geochemical techniques to the organic matter-lean Ratnek El Kahla section (Saharan Atlas, Algeria). During the Early Jurassic the study site was located at the northern Gondwana paleomargin, belonging to the southern West Tethys Shelf. The benthic barren interval coincides with the climax of the T-OAE that correlates with a major carbon cycle perturbation, expressed by a negative carbon isotope excursion. Compared to background values, sediments of the benthic barren interval are enriched in organic matter and redox-sensitive metals. In combination with the enhanced preservation of intact bacterial lipids and increased rates of organic matter sulfurization, data attest to a decline in pore water O₂ and increased H₂S concentration. It is thus reasonable to propose that, similar to northern shelf areas, benthic communities suffered from prolonged oxygen-deficient conditions. Absence of benthic activity and less intensive sediment reworking in combination with enhanced organic matter sulfurization favored organic matter preservation. Productivity proxies and δ¹⁵N data indicate moderate primary productivity rates. Lowered aqueous O₂ levels did not result from excessive aerobic organic matter breakdown. Seafloor anoxia was rather promoted by rising seawater temperatures and sluggish ocean circulation during a transition from icehouse into a greenhouse climate. These conditions may have been a pre-requirement for genesis of the T-OAE.

23628. 题目: Simulated photocatalytic aging of biochar in soil ecosystem: Insight into organic carbon release, surface physicochemical properties and cadmium sorption
文章编号: N20020804
期刊: Environmental Research
作者: Guixiang Quan, Qinya Fan, Liqiang Cui, Andrew R. Zimmerman, Hailong Wang, Zhiyuan Zhu, Bin Gao, Limin Wu, Jinlong Yan
更新时间: 2020-02-08
摘要: Photochemical/photocatalytic reaction, one of the aging pathway of biochar in soil, not only changed the physicochemical properties of biochar, but also affected the migration and transformation of pollutants. Wheat straw biochar was photocatalytic aged in a Fenton-like system using organic acid as buffer solution under light sources, the organic carbon release and surface chemical changes of biochar were investigated to illustrate the adsorption behaviors. With Fe(III) or α-Fe₂O₃ added, the total organic carbon (TOC) of aged biochar solution was influenced more by buffer system than light sources, with the highest of 420.59 mg L⁻¹ in citric acid system. The production of the hydroxyl radical (OH·) at citric/Fe(III) system was higher than the oxalic/Fe(III) system under the Hg lamp and showed an increasing trend with time. With light exposure, the porous structure of the biochar altered and surface area increased from 7.613 to 29.74 m² g⁻¹. Meanwhile, the adsorption of cadmium ion by biochar aged in citric/Fe(III) system also showed an increased adsorption capacity with a maximum of 73.54 mg g⁻¹. So, a well understanding of biochar physicochemical properties changes under natural ecosystem was undoubtedly useful for scientific assessment the long-term feasibility of biochar as soil remediation.
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23629. 题目: Model averaging for mapping topsoil organic carbon in France
文章编号: N20020803
期刊: Geoderma
作者: Songchao Chen, Vera Leatitia Mulder, Gerard B.M. Heuvelink, Laura Poggio, Manon Caubet, Mercedes Román Dobarco, Christian Walter, Dominique Arrouays
更新时间: 2020-02-08
摘要: The soil organic carbon (SOC) pool is the largest terrestrial carbon (C) pool and is two to three times larger than the C stored in vegetation and the atmosphere. SOC is a crucial component within the C cycle, and an accurate baseline of SOC is required, especially for biogeochemical and earth system modelling. This baseline will allow better monitoring of SOC dynamics due to land use change and climate change. However, current estimates of SOC stock and its spatial distribution have large uncertainties. In this study, we test whether we can improve the accuracy of the three existing SOC maps of France obtained at national (IGCS), continental (LUCAS), and global (SoilGrids) scales using statistical model averaging approaches. Soil data from the French Soil Monitoring Network (RMQS) were used to calibrate and evaluate five model averaging approaches, i.e., Granger-Ramanathan, Bias-corrected Variance Weighted (BC-VW), Bayesian Modelling Averaging, Cubist and Residual-based Cubist. Cross-validation showed that with a calibration size larger than 100 observations, the five model averaging approaches performed better than individual SOC maps. The BC-VW approach performed best and is recommended for model averaging. Our results show that 200 calibration observations were an acceptable calibration strategy for model averaging in France, showing that a fairly small number of spatially stratified observations (sampling density of 1 sample per 2500 km²) provides sufficient calibration data. We also tested the use of model averaging in data-poor situations by reproducing national SOC maps using various sized subsets of the IGCS dataset for model calibration. The results show that model averaging always performs better than the national SOC map. However, the Modelling Efficiency dropped substantially when the national SOC map was excluded in model averaging. This indicates the necessity of including a national SOC map for model averaging, even if produced with a small dataset (i.e., 200 samples). This study provides a reference for data-poor countries to improve national SOC maps using existing continental and global SOC maps.

23630. 题目: Development of pedotransfer functions by machine learning for prediction of soil electrical conductivity and organic carbon content
文章编号: N20020802
期刊: Geoderma
作者: K.K. Benke, S. Norng, N.J. Robinson, K. Chia, D.B. Rees, J. Hopley
更新时间: 2020-02-08
摘要: The pedotransfer function is a mathematical model used to convert direct soil measurements into known and unknown soil properties. It provides information for modelling and simulation in soil research, hydrology, environmental science and climate change impacts, including investigating the carbon cycle and the exchange of carbon between soils and the atmosphere to support carbon farming. In particular, the pedotransfer function can provide input parameters for landscape design, soil quality assessment and economic optimisation. The objective of the study was to investigate the feasibility of using a generalised pedotransfer function derived with a machine learning method to predict soil electrical conductivity (EC) and soil organic carbon content (OC) for different regional locations in the state of Victoria, Australia. This strategy supports a unified approach to the interpolation and population of a single regional soils database, in contrast to a range of pedotransfer functions derived from local databases with measurement sets that may have limited transferability. The pedotransfer function generation was based on a machine learning algorithm incorporating the Generalized Linear Mixed Model with interactions and nested terms, with Residual Maximum Likelihood estimation, and a predictor-frequency ranking system with step-wise reduction of predictors to evaluate the predictive errors in reduced models. The source of the data was the Victorian Soil Information System (VSIS), which is a database administered for soil information and mapping purposes. The database contains soil measurements and information from locations across Victoria and is a repository of historical data, including monitoring studies. In total, data from 93 projects were available for inputs to modelling and analysis, with 5158 samples used to derive predictors for EC and 1954 samples used to derive predictors for OC. Over 500 models were tested by systematically reducing the number of predictors from the full model. Five-fold cross-validation was used for estimation of model mean-squared prediction error (MSPE) and mean-absolute percentage error (MAPE). The results were statistically significant with only a gradual reduction in error for the top-ranked 50 models. The prediction errors (MSPE and MAPE) of the top ranked model for EC are 0.686 and 0.635, and 0.413 and 0.474 for OC respectively. The four most frequently occurring predictors both for EC and OC prediction across the full set of models were found to be soil depth, pH, particle size distribution and geomorphological mapping unit. The possible advantages and disadvantages of this approach were discussed with respect to other machine learning approaches.

23631. 题目: Comparing laboratory and airborne hyperspectral data for the estimation and mapping of topsoil organic carbon: Feature selection coupled with random forest
文章编号: N20020801
期刊: Soil and Tillage Research
作者: Yongsheng Hong, Songchao Chen, Yiyun Chen, Marc Linderman, Abdul M. Mouazen, Yaolin Liu, Long Guo, Lei Yu, Yanfang Liu, Hang Cheng, Yi Liu
更新时间: 2020-02-08
摘要: Rapid monitoring of soil organic carbon (SOC) with fine sampling resolution is vital for further understanding of the global carbon cycle and sustainable management of soil resources. Proximal visible and near-infrared (Vis–NIR) spectroscopy is an effective approach to analyze SOC. However, this technique can only be used for point-to-point monitoring and not for grid pixels evenly spread throughout the area. Airborne hyperspectral imagery with high-spectral- and spatial-resolution provides a promising tool for mapping topsoil SOC at a fine scale, but suffers from the interference of some external factors. Using 45 topsoil samples collected from an agricultural field in the United States, this study aimed to compare the potential of airborne hyperspectral image in estimating and mapping of bare topsoil SOC with that derived from proximal laboratory Vis–NIR spectral data. Random forest (RF) along with two advanced feature selection algorithms, namely, continuous wavelet transform (CWT) and competitive adaptive reweighted sampling (CARS), was applied to optimize the performance of the prediction models. Results showed that laboratory and airborne spectra presented similar spectral shapes and strengths, but laboratory spectral curves were smoother than airborne spectral curves, which were noisier. Laboratory spectra (R² = 0.79–0.87) performed better than airborne hyperspectral imagery (R² = 0.49–0.76) in cross-validation, regardless of feature selection algorithms. The CWT-RF models resulted in the highest cross-validation results for laboratory (R² = 0.87) and airborne (R² = 0.76) spectra, suggesting their robustness in SOC prediction. The SOC maps retrieved from full-spectrum-RF, CWT-RF, and CARS-RF models all exhibited similar spatial distribution patterns. With airborne hyperspectral imagery serving as a valuable data source at pixel level for digital soil mapping, the methodological framework proposed in this paper could improve the accuracy and reduce the prediction uncertainty of SOC maps by selecting and adopting the optimal subset of spectral variables.

23632. 题目: Sources of Particulate Organic Matter across Mangrove Forests and Adjacent Ecosystems in Different Geomorphic Settings
文章编号: N20020710
期刊: Wetlands
作者: Daniel A. Saavedra-Hortua, Daniel A. Friess, Martin Zimmer, Lucy Gwen Gillis
更新时间: 2020-02-07
摘要: Mangrove forests are among the world's most productive ecosystems and provide essential ecosystem services such as global climate regulation through the sequestration of carbon. A detailed understanding of the influence of drivers of ecosystem connectivity (in terms of exchange of suspended particulate organic matter), such as geomorphic setting and carbon stocks, among coastal ecosystems is important for being able to depict carbon dynamics. Here, we compared carbon stocks, CO2 fluxes at the sediment-air interface, concentrations of dissolved organic carbon and suspended particulate organic carbon across a mangrove-seagrass-tidal flat seascape. Using stable isotope signatures of carbon and nitrogen in combination with MixSIAR models, we evaluated the contribution of organic matter from different sources among the different seascape components. Generally, carbon concentration was higher as dissolved organic carbon than as suspended particulate matter. Geomorphic settings of the different locations reflected the contributions to particulate organic matter of the primary producers. For example, the biggest contributors in the riverine location were mangrove trees and terrestrial plants, while in fringing locations oceanic and macroalgal sources dominated. Anthropogenic induced changes at the coastal level (i.e. reduction of mangrove forests area) may affect carbon accumulation dynamics in adjacent coastal ecosystems.

23633. 题目: Spatial variability of organic matter degradability in tidal Elbe sediments
文章编号: N20020709
期刊: Journal of Soils and Sediments
作者: Florian Zander, Timo Heimovaara, Julia Gebert
更新时间: 2020-02-07
摘要: Purpose: The microbial turnover of sediment organic matter (OM) in ports and waterways impacts water quality, sonic depth finding and presumably also rheological properties as well as greenhouse gas emissions, especially if organic carbon is released as methane. As a consequence, sediment management practices as a whole are affected. This study aimed to discern spatial OM degradability patterns in the Port of Hamburg and investigated correlations with standard analytical properties as a basis for future predictive modelling. Materials and methods: Sediments in the Port of Hamburg were repeatedly sampled at nine locations along an east-west transect using a 1-m corer. In a stratified sampling approach, layers of suspended particulate matter (SPM), fluid mud (FM), pre-consolidated sediment (PS) and consolidated sediment (CS) were identified and individually analysed for long-term aerobic and anaerobic degradation of organic matter, DNA concentration, stable carbon isotope signature, density fractions and standard solids and pore water properties. Results and discussion: The investigation area was characterised by a distinct gradient with a 10-fold higher OM degradability in upstream areas and lower degradability in downstream areas. Concomitantly, upstream locations showed higher DNA concentrations and more negative δ¹³C values. The share of bulk sediment in the heavy density fraction as well as the proportion and absolute amount of organic carbon were significantly larger at downstream locations. A depth and hence age-related gradient was found at individual locations, showing higher degradability of the upper, younger material, concomitant with higher DNA concentration, and lower OM turnover in the deeper, older and more consolidated material. Deeper layers were also characterised by higher concentrations of pore water ammonium, indicative of anaerobic nitrogen mineralisation. Conclusions: Organic matter lability is inversely linked to its stabilisation in organo-mineral complexes. The observed degradability gradient is likely due to the different OM quality in relation to its origin. Downstream OM enters the system with the tidal flood current from the direction of the North Sea whereas upstream locations receive OM originating from the catchment, containing more autochthonous, plankton-derived and more easily degradable components. At individual sampling points, depth-related degradability gradients reflect an age gradient, with easily degradable material in top layers and increasing stabilisation of OM in organo-mineral compounds with depth.

23634. 题目: Spent mushroom substrates affect soil humus composition, microbial biomass and functional diversity in paddy fields
文章编号: N20020708
期刊: Applied Soil Ecology
作者: Fangliang Li, Qingbo Kong, Qing Zhang, Huangping Wang, Limin Wang, Tao Luo
更新时间: 2020-02-07
摘要: Spent mushroom substrate (SMS) is the residue after mushroom production. The aims of this work were to analyze the effects of continuous application of SMS for nearly 10 years on soil organic carbon (SOC), soil humus composition, microbial biomass and functional diversity in paddy fields and to provide a theoretical basis for scientific application of SMS. A continuous application of SMS from Agaricus bisporus experiment was established in paddy field of southeastern China in 2007. Soils were collected from 6 treatments in 2016. The results showed that application of SMS could significantly increase the contents of SOC, soil total alkali-soluble humic carbon (HEC), humic acid carbon (HAC), especially the treatment of with high quantity of SMS, but not significantly increase the content of fulvic acid carbon (FAC). The microbial biomass carbon and nitrogen contents of MR3 (the amounts of SMS were 9574.5 kg hm⁻², converted to pure nitrogen were 180 kg hm⁻²) were the largest, it illustrated that the amount of SMS was not the more the better. The average well color development (AWCD), the Shannon index, Simpson index and McIntosh index of MR3 treatment were the highest. Microorganisms of MR3 treatment could make better use of carbon sources. Carboxylic acids, carbohydrates and polymers were the main carbon source types. Sufficient but not excessive application of SMS was beneficial to the carbon source utilization of fast-growing microorganisms and was considered to be a good way to improve the productivity of paddy soil.

23635. 题目: Relevance of biochar to influence the bacterial succession during pig manure composting
文章编号: N20020707
期刊: Bioresource Technology
作者: Mukesh Kumar Awasthi, Yumin Duan, Tao Liu, Sanjeev Kumar Awasthi, Zengqiang Zhang
更新时间: 2020-02-07
摘要: The influence of pig manure biochar amendment (PMBA) during the pig manure (PM) and wheat straw (WS) composting was evaluated. Five concentration of PMBA (0%, 2%, 4%, 6% and10%) were applied to explore the bacterial distributions in PM compost by 16SDNA amplicons sequencing. The results showed that the addition of 6% PMBA could significantly enhanced the bacterial community abundance compared with other composts, while control has relative less bacterial population (332 OTU). The visualization of phylogenetic tree and krona demonstrated the distinctive distribution of each composts, suggested that biochar dosages have an influence on bacterial communities’ variation during co-composting. Beta-diversity of distance matrix heat-map and principal component analysis confirmed that bacterial communities were considerably correlated with increasing PMBA. Redundancy also confirmed the similarity and discrepancy among all treatments and environmental factors. This work considered as the potential of PMBA as a booster in composting, where T4 has most plentiful bacterial community and diversity.

23636. 题目: Release of colloidal biochar during transient chemical conditions: The humic acid effect
文章编号: N20020706
期刊: Environmental Pollution
作者: Yang Wang, Scott A. Bradford, Jianying Shang
更新时间: 2020-02-07
摘要: Our understanding of colloidal biochar (CB) transport and release is largely unknown in environments with transient chemical conditions, e.g., ionic strength (IS), pH, and especially humic acid (HA). In this study, column experiments were conducted to investigate CB transport and retention in the presence and absence of HA, and CB release under transient IS and pH conditions in saturated sand. Step reductions in solution IS from 25 to 0.01 mM produced significant release peaks of CB due to a reduction in the depth of the primary minima on rough surfaces with small energy barriers. In contrast, step increases of solution pH from 4 to 10 only slightly increased CB release presumably due to the strong buffering capacity of CB. The CB retention was diminished by HA during the deposition phase. However, the release of CB with transients in IS and pH was not influenced much when deposition occurred in the presence of HA. These observations indicate that HA increased the energy barrier during deposition but did not have a large influence on the depth of the interacting minimum during transient release. Potential explanations for these effects of HA on CB retention and transient release include enhanced repulsive electrostatic interactions and/or altering of surface roughness properties. Our findings indicated that the release of retained CB is sensitive to transient IS conditions, but less dependent on pH increases and CB deposition in the presence of HA. This information is needed to quantify potential benefits and/or adverse risks of mobile CB in natural environments.
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23637. 题目: Soil Organic Carbon across Mexico and the conterminous United States (1991‐2010)
文章编号: N20020705
期刊: Global Biogeochemical Cycles
作者: Mario Guevara, Carlos Arroyo, Nathaniel Brunsell, Carlos O. Cruz, Grant Domke, Julian Equihua, Jorge Etchevers, Daniel Hayes, Tom Hengl, Alejandro Ibelles, Kris Johnson, Ben de Jong, Zamir Libohova, Ricardo Llamas, Lucas Nave, Jose L. Ornelas, Fernando Paz, Rainer Ressl, Anita Schwartz, Arturo Victoria, Skye Wills, Rodrigo Vargas
更新时间: 2020-02-07
摘要: Soil Organic Carbon (SOC) information is fundamental for improving global carbon cycle modeling efforts, but discrepancies exist from country‐to‐global scales. We predicted the spatial distribution of SOC stocks (topsoil; 0‐30 cm) and quantified modeling uncertainty across Mexico and the conterminous United States (CONUS). We used a multi‐source SOC dataset (>10000 pedons, between 1991‐2010) coupled with a simulated annealing regression framework that accounts for variable selection. Our model explained ~50% of SOC spatial variability (across 250m grids). We analyzed model variance, and the residual variance of six conventional pedotransfer functions for estimating bulk density (BD) to calculate SOC stocks. Two independent datasets confirmed that the SOC stock for both countries represents between 46 and 47 Pg with a total modeling variance of ±12 Pg. We report a residual variance of 10.4 ±5.1 Pg of SOC stocks against the six pedotransfer functions. When reducing training data to defined decades with relatively higher density of observations (1991‐2000 and 2001‐2010, respectively), model variance for predicted SOC stocks ranged between 41 and 55 Pg. We found nearly 42% of SOC across Mexico in forests and 24% in croplands; whereas 31% was found in forests and 28% in croplands across CONUS. Grasslands and shrublands stored 29 and 35% of SOC across Mexico and CONUS, respectively. We predicted SOC stocks >30% below recent global estimates that do not account for uncertainty and are based on legacy data. Our results provide

23638. 题目: The use of amino sugars for assessing seasonal dynamics of particulate organic matter in the Yangtze River estuary
文章编号: N20020704
期刊: Marine Chemistry
作者: Chengzhe Ren, Huamao Yuan, Jinming Song, Liqin Duan, Xuegang Li, Ning Li, Bu Zhou
更新时间: 2020-02-07
摘要: The particulate amino sugars (PAS), organic carbon (POC) and nitrogen (PN), the chlorophyll a (Chl-a), and the heterotrophic bacterial cell count (HBC) in the Yangtze River Estuary (YRE) were determined to study the biological source, bioavailability and bacterial contribution of particulate organic matter (POM) under the influence of algal bloom during the spring and autumn of 2017. The contents of PAS were 2.6–69.6 nmol/(mg dw) and made up 5.29 ± 2.55% of POC and 5.39 ± 2.77% of PN. The strong positive correlations between Chl-a and POC, PN and PAS and their similar distributions indicated that phytoplankton was a major source of POM and PAS in the YRE. When algal blooms occurred, the high ratios of glucosamine to galactosamine (GlcN/GalN) (~10.9) and the high carbon and nitrogen normalized yields of PAS (%PAS-POC and %PAS-PN, respectively) clearly indicated the planktonic (especially zooplankton) source of POM, although the high muramic acid (Mur) contents implying high contents of fresh bacterial organic matter (OM) were also found. Additionally, the high proportion of fresh plankton- and bacterial-derived OM indicated that the POM was more labile when algal bloom occurred. In contrast, when the primary production was low, the lower %PAS-POC and GlcN/GalN ratios (< 3) in the POM demonstrated the decreased contribution of planktonic OM and the relatively elevated contribution of bacterial OM. In addition, the higher %PAS-PN and the lower DO concentrations in seawater indicated that the POM experienced some degree of degradation but was still at an early stage in the nearshore site in autumn. In spring, the Changjiang diluted water (CDW) carried considerable plankton-derived POM into the estuary and influenced the distribution of POM. In autumn, the terrestrial OM might become more bacterial-derived and had less influence on the bulk POM of the estuary. The bacterial OM estimated by the Mur accounted for an average of 10.8 ± 3.7% and 40.5 ± 19.1% of the POC in spring and autumn, respectively, which was approximately two times higher than the results based on the heterotrophic bacterial cell count (HBC), indicating that most of the bacterial OM in the POM was detritus. In summary, the content, source and bioavailability of POM were significantly affected by algal bloom and the CDW, and the amino sugars represent a reliable tool to indicate the source and bioavailability of POM.

23639. 题目: Hydrologic connectivity determines dissolved organic matter biogeochemistry in northern high‐latitude lakes
文章编号: N20020703
期刊: Limnology and Oceanography
作者: Sarah Ellen Johnston, Robert G. Striegl, Matthew J. Bogard, Mark M. Dornblaser, David E. Butman, Anne M. Kellerman, Kimberly P. Wickland, David C. Podgorski, Robert G. M. Spencer
更新时间: 2020-02-07
摘要: Northern high‐latitude lakes are undergoing climate‐induced changes including shifts in their hydrologic connectivity with terrestrial ecosystems. How this will impact dissolved organic matter (DOM) biogeochemistry remains uncertain. We examined the drivers of DOM composition for lakes in the Yukon Flats Basin in Alaska, an arid region of low relief that is characteristic of over one‐quarter of circumpolar lake area. Utilizing the vascular plant biomarker lignin, chromophoric dissolved organic matter (CDOM), and ultrahigh‐resolution mass spectrometry, we interpreted DOM compositional changes using lake‐water stable isotope (δ¹⁸O‐H₂O) composition as a proxy for lake hydrologic connectivity with the landscape. We observed a relative decrease in CDOM in more hydrologically isolated lakes (enriched δ¹⁸O‐H₂O) without a corresponding decrease in dissolved organic carbon (DOC) concentration. Although DOC and CDOM were weakly correlated, a significant positive relationship between lignin and CDOM (r² = 0.67) demonstrates that optical parameters are useful for estimating lignin concentration and thus vascular plant contribution to lake DOM. Indicators of allochthonous DOM, including lignin carbon normalized yields, CDOM aromaticity proxies, and relative abundances of polyphenolic and condensed aromatic compound classes, were negatively correlated with δ¹⁸O‐H₂O (r² > 0.45), suggesting there is little allochthonous DOM supplied to many of these hydrologically isolated lakes. We conclude that decreased lake hydrologic connectivity, driven by ongoing climate change (i.e., decreased precipitation, warming temperatures), will reduce allochthonous DOM contributions and shift lakes toward lower CDOM systems with ecosystem‐scale ramifications for heat transfer, photochemical reactions, productivity, and ultimately their biogeochemical function.

23640. 题目: Effect of deashing on activation process and lead adsorption capacities of sludge-based biochar
文章编号: N20020702
期刊: Science of The Total Environment
作者: Junjie Zhang, Jingai Shao, Qianzheng Jin, Xiong Zhang, Haiping Yang, Yingquan Chen, Shihong Zhang, Hanping Chen
更新时间: 2020-02-07
摘要: To explore the effect of inorganic minerals on activation process and lead adsorption of sludge-based biochar, sludge-based biochar was pre-deashed using hydrochloric acid or hydrofluoric acid followed by potassium acetate activation. The results indicate that hydrochloric or hydrofluoric acid deashing can improve the pore parameters of sludge-based biochars and promote subsequent activation effect of potassium acetate. The specific surface area of biochar activated by potassium acetate after hydrochloric acid and hydrofluoric acid pretreatment increased from 583.36 m²/g to 718.70 m²/g and 991.55 m²/g, respectively. The enhancement of pore structure is conducive to enhancing the physical adsorption of lead on sludge-based biochar, while the chemical adsorption is not significantly affected at the same time. Thereby, the biochar and activated biochar pretreated with hydrofluoric acid showed better lead adsorption capacities (16.70 and 49.47 mg/g) than untreated biochar (7.56 and 38.49 mg/g).
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