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25181. 题目: Raman spectroscopy as a tool to determine the thermal maturity of organic matter: Application to sedimentary, metamorphic and structural geology
文章编号: N19082501
期刊: Earth-Science Reviews
作者: Delano G. Henry, Ian Jarvis, Gavin Gillmore, Michael Stephenson
更新时间: 2019-08-25
摘要: Raman spectrometry is a rapid, non-destructive alternative to conventional tools used to assess the thermal alteration of organic matter (OM). Raman may be used to determine vitrinite reflectance equivalent OM maturity values for petroleum exploration, to provide temperature data for metamorphic studies, and to determine the maximum temperatures reached in fault zones. To achieve the wider utilisation of Raman, the spectrum processing method, the positions and nomenclature of Raman bands and parameters, all need to be standardized. We assess the most widely used Raman parameters as well as the best analytical practices that have been proposed. Raman band separation and G-band full-width at half-maximum are the best parameters to estimate the maturity for rocks following diagenesis–metagenesis. For metamorphic studies, the ratios of band areas after performing deconvolution are generally used. Further work is needed on the second-order region, as well as assessing the potential of using integrated areas on the whole spectrum, to increase the calibrated temperature range of Raman parameters. Applying Raman spectroscopy on faults has potential to be able to infer both temperature and deformation processes. We propose a unified terminology for OM Raman bands and parameters that should be adopted in the future. The popular method of fitting several functions to a spectrum is generally unnecessary, as Raman parameters determined from an un-deconvoluted spectrum can track the maturity of OM. To progress the Raman application as a geothermometer a standardized approach must be developed and tested by means of an interlaboratory calibration exercise using reference materials.

25182. 题目: Organotin Release from Polyvinyl Chloride Microplastics and Concurrent Photodegradation in Water: Impacts from Salinity, Dissolved Organic Matter, and Light Exposure
文章编号: N19082417
期刊: Environmental Science & Technology
作者: Chunzhao Chen, Ling Chen, Ying Yao, Francisco Artigas, Qinghui Huang, Wen Zhang
更新时间: 2019-08-24
摘要: Photochemical weathering leads to degradation of microplastics and releases chemical additives, polymeric fragments, and/or byproducts. This study evaluated the release kinetics of organotin compounds (OTCs) from three different sized (10–300 μm) polyvinyl chloride (PVC) microplastics under UV- and visible light irradiation. Four OTCs, dimethyltin (DMT), monomethyltin (MMT), dibutyltin (DBT), and monobutyltin (MBT), were found to release from PVC particles after 24 h leaching in darkness ranging from 2 to 20 μg·g-PVC–1. Under UV/visible light irradiation, only DMT and DBT were detectable, whereas MMT and MBT were not detected due to rapid photodegradation. The total tin concentrations (including organic and inorganic tins) in the aqueous phase monotonically increased under light exposure. By contrast, they reached plateaus after 24 h in darkness, confirming the photodegradation of OTCs. A release kinetics model was established and correctly interpreted the microplastics size effect on the OTC release process. Finally, the impacts of salinity and dissolved organic matter (DOM) were investigated. The release and photodegradation of OTCs were both inhibited at high salinity conditions, probably due to the enhanced readsorption of OTCs on PVC microplastics and the formation of halogen radicals that were less reactive toward neutral OTCs. The presence of DOM, however, increased OTCs release probably because the excited state triplet DOM (3DOM*) formed and reacted with OTCs from PVC microplastics.

25183. 题目: Compositional characteristics of fluvial particulate organic matter exported from the world's largest alpine wetland
文章编号: N19082416
期刊: Journal of Geophysical Research: Biogeosciences
作者: Guohua Dai, Erxiong Zhu, Zongguang Liu, Yiyun Wang, Shanshan Zhu, Simin Wang, Tian Ma, Juan Jia, Xin Wang, Shengjie Hou, Pingqing Fu, Francien Peterse, Xiaojuan Feng
更新时间: 2019-08-24
摘要: Wetlands are hotspots for particulate organic matter (POM) supply into rivers, which link the land‐ocean transfer in the global carbon cycle. However, the source, composition and seasonal variability of POM carried by wetland‐draining rivers are poorly constrained. Here we combine bulk and source‐specific biomarker analyses to investigate the fluvial POM biogeochemistry of the Black and White Rivers draining from the Zoige wetland. We find that POM was dominated by terrestrial organic matter including high‐molecular‐weight (HMW) lipids, branched glycerol dialkyl glycerol tetraethers (brGDGTs) and lignin phenols. However, fluvial POM was rich in HMW lipids and poor in lignin phenols compared to the catchment soils, possibly due to hydrodynamic sorting and dissolution processes. While lignin phenol concentrations were higher in the wet season, HMW lipid concentrations were lower. Additionally, lignin phenols increased with total suspended solids while HMW lipids decrease. These contrasts imply an enhanced input of lignin‐rich particles from soil surface layers in the wet season, diluting HMW lipids. Compared with other rivers around the world with a higher forest coverage in the catchment, POM in the Black and White Rivers draining grass‐dominated wetlands had a much higher ratio of HMW fatty acids to lignin phenols. Our results represent a benchmark study highlighting compositional characteristics of fluvial POM exported from the Zoige wetland and the divergent behavior of molecular components during fluvial transfer. Such information is vital for assessing future changes in the Zoige wetland, given its high vulnerability to climatic and land‐use changes.

25184. 题目: Membrane photo-bioreactor coupled with heterogeneous Fenton fluidized bed for high salinity wastewater treatment: Pollutant removal, photosynthetic bacteria harvest and membrane anti-fouling analysis
文章编号: N19082415
期刊: Science of The Total Environment
作者: Chang Li, Xiong Li, Lei Qin, Wei Wu, Qin Meng, Chong Shen, Guoliang Zhang
更新时间: 2019-08-24
摘要: In this study, efficient photosynthetic bacteria (PSB)-GO/PVDF membrane photo-bioreactor (MPBR) combined with heterogeneous Fenton fluidized bed was built and successfully applied for treatment of actual refractory seafood-processing wastewater with extremely high salinity. As effective pre-treatment, heterogeneous Fenton was designed for removing non-biodegradable organics and reducing iron-sludge discharge. In MPBR, GO/PVDF membrane fabricated by chemical grafting GO nanosheets was first used for salt-tolerated PSB harvest. Compared with original PVDF membrane, GO/PVDF membrane exhibited enhanced hydrophilicity, better permeability (4.4 times) and attractive flux recover rate (94%), which was attributed to remarkable reduction in hydrophobic proteins amount of extracellular polymeric substances (EPS). Importantly, COD and NH₃-N removal efficiency of MPBR with GO/PVDF membrane were kept about 95 and 98%, respectively, and average biomass productivity reached as high as 105 mg/L·d. This study provides a promising and economical way to build efficient MBR combined with new materials for high salinity hazardous wastewater treatment.
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25185. 题目: Earthworm activities weaken the immobilizing effect of biochar as amendment for metal polluted soils
文章编号: N19082414
期刊: Science of The Total Environment
作者: Jie Wang, Liang Shi, Xinzhe Zhang, Xuan Zhao, Kecheng Zhong, Shengxiao Wang, Jianwen Zou, Zhenguo Shen, Yahua Chen
更新时间: 2019-08-24
摘要: The effect of earthworms on the immobilization of heavy metals by biochar was investigated using 4-week soil pot experiments. Our results showed that both sludge and rice husk biochars applied to Cd, Pb and Zn contaminated soils significantly reduced the bioavailability of those heavy metals in soils, and their concentrations in soil pore water. The Cd and Pb concentrations in pakchoi shoots were decreased by 10.8%–11.7% and 21.5%–26.5%, respectively, in biochar treatments alone. Biochar and earthworm treatments, alone or in combination, can significantly increase pakchoi growth. However, compared with biochar-treated alone, applying earthworms into pots with biochar treatments significantly reduced soil pH by 0.1–0.19 units, increased the Cd, Pb and Zn concentrations in soil pore water, their bioavailability and total uptake in shoots. Additionally, earthworms weaken the immobilization effect of biochar on heavy metals. The results of principal component analysis and correlation analysis showed that earthworm treatment was the main cause of soil pH reduction, and soil pH was significantly negatively correlated with the bioavailable Cd, Pb and Zn concentrations in the soil. Furthermore, the effect of the earthworm digestive system (casts) on bioavailable Cd, Pb and Zn concentrations could not explain their changes in the soil. In addition, the application of biochar had no significant effect on the survival and heavy metal enrichment of earthworm. Therefore, the effect of earthworms must be considered in the process of Cd, Pb and Zn contaminated farmland soil remediation using biochar.
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25186. 题目: Assessing the contribution of hydroxylation species in the photochemical transformation of primidone (pharmaceutical)
文章编号: N19082413
期刊: Science of The Total Environment
作者: Yingjie Liu, Shuwen Yan, Lushi Lian, Jianzhong Ma, Huaxi Zhou, Weihua Song
更新时间: 2019-08-24
摘要: Pharmaceutical and personal care products (PPCPs) are a group of emerging contaminants that have frequently been detected in aqueous environments. Phototransformation driven by solar irradiation is one of the most important natural processes for the elimination of PPCPs. In this study, primidone (PMD) was chosen as a model “photorefractory” compound. A series of experiments were conducted to assess if reactive intermediates (RIs), such as hydroxyl radical (HO), singlet oxygen (¹O₂), and triplet states of dissolved organic matter (³DOM^⁎), inhibited or enhanced the photochemical transformation of PMD under simulated solar irradiation. The results indicate that HO plays a key role in the photodegradation of PMD and that dissolved oxygen can affect the degradation rate of PMD by promoting HO formation. Our results demonstrated that PMD can not only react with free HO (HO_-free) but also react with lower-energy hydroxylation agents (HO_-like). The contributions of HO_-free and HO_-like to PMD degradation in various dissolved organic matter (DOM) solutions were estimated by a methane-quenching experiment. The results indicated that the HO_-like species were important in the photodegradation of “photorefractory” compounds. The bimolecular reaction rate constant of the reaction of free HO with PMD was measured as (5.21 ± 0.02) × 10⁹ M⁻¹ s⁻¹ by using electron pulse radiolysis. Furthermore, PMD was used as a probe to estimate the steady-state concentration of HO_-free in various DOM solutions. Using the multivariate statistical strategies of orthogonal projection to latent structures discriminant analysis (OPLS-DA) and hierarchical clustering, 28 photochemical transformation products (TPs) of PMD were successfully identified from the DOM matrix.
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25187. 题目: Characterization of phosphorus engineered biochar and its impact on immobilization of Cd and Pb from smelting contaminated soils
文章编号: N19082412
期刊: Journal of Soils and Sediments
作者: Jing Ren, Zixuan Zhao, Amjad Ali, Weidou Guan, Ran Xiao, Jim J. Wang, Sirui Ma, Di Guo, Baoyue Zhou, Zengqiang Zhang, Ronghua Li
更新时间: 2019-08-24
摘要: Purpose: Biochar has been used as an amendment to immobilize toxic metals (TMs) and increase nutrient content in the contaminated soil. In this study, Ca(H₂PO₄)₂-engineered swine manure biochar (PSMB) and swine manure biochar (SMB) were prepared and investigated to evaluate their effects on the availability of toxic metals (Cd and Pb) and soil nutrient content in Fengxian (FX)- and Kunming (KM)-contaminated soils through incubation experiment. Materials and methods: The soil samples were collected at 0–20 cm depth from two contaminated farmlands close to abandoned Pb smelters, which are located in FX and KM. Swine manure was obtained from the rural hog lot in Yangling, China. Each biochar (SMB and PSMB) was mixed with the air-dried soil samples (FX and KM) at a dosage of 1% and 3% w/w, respectively. Then, a portion of 3 kg of the mixture was placed in plastic pots and incubated for 30 days in a greenhouse. After the soil incubation experiment, pot experiments were performed in a greenhouse of Northwest A&F University, Yangling, China. Results and discussion: Adding PSMB at a rate of 3% maximally decreased the concentrations of DTPA-extractable Cd (34.02 and 47.73%) and Pb (18.70 and 24.58%) in FX and KM soil. The BCR data revealed that the percentage of acid-soluble Cd and Pb fraction in FX and KM soils remarkably decreased whereas the percentages of residual Cd fraction and reducible Pb fraction in FX and KM soils significantly increased in all the biochar-amended soils compared with control. To confirm these results, a pot experiment was conducted to investigate the effects of amendments on growth and uptake of toxic metals in Chinese cabbage (Brassica rapa L. spp. pekinensis). The results showed that the addition of PSMB3% significantly (P < 0.05) increased the biomass of plants and reduced the absorption of toxic metals in plant. Conclusions: The results revealed that the dry biomass increased and the absorption of toxic metals decreased in plants. All treatments of biochar were beneficial and application of PSMB 3% was most effective in enhancing plant biomass and reducing the accumulation of toxic metals in the plants.

25188. 题目: Advances in production and application of biochar from lignocellulosic feedstocks for remediation of environmental pollutants
文章编号: N19082411
期刊: Bioresource Technology
作者: P.R. Yaashikaa, P. Senthil Kumar, Sunita J. Varjani, A. Saravanan
更新时间: 2019-08-24
摘要: Thermochemical processing of biomass results in a producing char, a typical by-product. The char can be termed as biochar when specifically applied as a soil fertility enhancement. Biochar, when utilized efficiently, is basic for enhancing financial viability and also to maintain ecosystem. The properties of carbonized biomass rely upon raw materials (feedstock) and procedure conditions. Biochar shows an incredible potential to effectively handle water contaminants taking into consideration the wide accessibility of feedstock, suitable physical/chemical surface properties and low-cost. Pyrolysis technology for converting lignocellulosic biomass into biochar has emerged as a frontier research domain for the removal of pollutants. This review focused on production of biochar from various sources of lignocellulosic biomass (cellulose, hemicellulose and lignin) and its application in various fields such as agriculture, wastewater treatment process. Biochar is a significant resource however, its application require further examination of its properties and structure and techniques to alter those factors.
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25189. 题目: Biochar triggering multipath methanogenesis and subdued propionic acid accumulation during semi-continuous anaerobic digestion
文章编号: N19082410
期刊: Bioresource Technology
作者: Junyi Ma, Junting Pan, Ling Qiu, Quan Wang, Zengqiang Zhang
更新时间: 2019-08-24
摘要: The semi-continuous anaerobic digestion (AD) performances of dry chicken manure (DCM) were investigated at the temperature of 35 ± 1 °C with and without biochar. The average specific methane productions of 0.18 L/g VS_added and 0.17 L/g VS_added were achieved without biochar at the organic loading rate (OLR) of 3.125 and 6.25 g VS/L/d, respectively. An increase of 12% in methane production was obtained in the presence of biochar at the two operational OLRs. Accumulation of propionic acid was observed associating with AD of DCM, which was substantially alleviated by biochar supplement. The buffer capacity of biochar was supposed to develop through strengthening the buffer system established by NH₄⁺ and volatile fatty acids. Methanosarcina that can utilize multiple nutrients for methanogenesis was the dominant archaea in the presence of biochar, while the strictly aceticlastic Methanosaeta was dominant in control digester. These results suggest that biochar enhanced methanogenesis through intensifying its available pathway.

25190. 题目: Activation of persulfate by CO₂-activated biochar for improved phenolic pollutant degradation: Performance and mechanism
文章编号: N19082409
期刊: Chemical Engineering Journal
作者: Chen Sun, Tong Chen, Qunxing Huang, Mingxiu Zhan, Xiaodong Li, Jianhua Yan
更新时间: 2019-08-24
摘要: Environment-friendly and low-cost catalysts are important for persulfate based advanced oxidation processes. In this study, we reported a CO₂-activated biochar (AC) as a low-cost and efficient catalyst for persulfate (PS) activation and the degradation of phenol and chlorophenols. The AC950 showed the best catalytic performance for PS with an oxidant utility of 0.5 mol/mol oxidant/h/g with an activation energy of 15.86 kJ/mol owing to its large surface area, rich surface defects, and well-modified oxygen functional groups. In contrast to a radical-based mechanism, this novel biochar/persulfate system works through a non-radical mechanism that includes singlet state oxygen generation and an electron transfer reaction pathway. The major degradation intermediate of the phenolic pollutant was identified to be benzoquinone; moreover, amongst chlorophenols, the para-chlorine substituent was the first to degrade. The durability of the catalyst was low, it was deactivated primarily because of the oxidation of the carbon surface, and thermal regeneration was determined to be efficient for its recovery. Furthermore, HCO₃⁻ and HPO₄²⁻ were found to considerably inhibit the performance of the catalytic oxidation system.
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25191. 题目: Insight into the influence of pyrolysis temperature on Fenton-like catalytic performance of magnetic biochar
文章编号: N19082408
期刊: Chemical Engineering Journal
作者: Yunqiang Yi, Guoquan Tu, Pokeung Eric Tsang, Zhanqiang Fang
更新时间: 2019-08-24
摘要: The effects of the pyrolysis temperature on the Fenton-like catalytic performance of magnetic biochar remain unclear. In this study, magnetic biochar (SMBC300, SMBC400, SMBC500) was synthesised at various temperature (300 °C, 400 °C and 500 °C) and used for the Fenton-like degradation of metronidazole. The characterisation results demonstrated the similarity of functional groups and the species of iron oxides in three types of magnetic biochar. Moreover, the size distribution of iron oxides in these composites were obviously affected by the pyrolysis temperature. Metronidazole was rapidly and completely degraded by SMBC400 coupled with H₂O₂, and its kinetic rate constant was approximately 1.86 and 3.04 times higher than those of SMBC300 and SMBC500, respectively. Electron spin resonance and free radical quenching experiments showed that obvious differences in the ability of three types of magnetic biochar can heterogeneously activate H₂O₂ to generate OH, and that surface-bound OH plays a key role in the degradation of metronidazole. The differences in Fe (II) content among the types of magnetic biochar were the main reason for the differences in catalytic performance. The degradation of metronidazole by various species of iron oxides showed that FeO was the key component in the catalytic performance of magnetic biochar. This study confirms that magnetic biochar prepared at 400 °C has the best performance in the Fenton-like degradation of metronidazole.

25192. 题目: Effects of nitrogen deposition and biochar amendment on soil respiration in a Torreya grandis orchard
文章编号: N19082407
期刊: Geoderma
作者: Junbo Zhang, Quan Li, Jiasheng Wu, Xinzhang Song
更新时间: 2019-08-24
摘要: Torreya grandis is an important economic nut tree species in southeastern China, but there is little information about its CO₂ efflux under increasing atmospheric nitrogen (N) deposition. There are few studies that assess the response of soil respiration to biochar applications in orchard soils under N deposition conditions. We investigated changes in soil respiration rate and other environmental factors under a factorial combination of biochar amendment (BC0: 0 t ha⁻¹, BC1: 20 t ha⁻¹, BC2: 40 t ha⁻¹) and simulated additional N deposition (N0: 0 kg N ha⁻¹ yr⁻¹, NL: 30 kg N ha⁻¹ yr⁻¹ and NH: 60 kg N ha⁻¹ yr⁻¹) treatments over three years (2016–2018). Soil respiration rate showed significant seasonal changes, with the highest rates occurring in summer and the lowest occurring in winter. The annual CO₂ emission amount of the control was 3.1 ± 0.03 kg CO₂ m⁻². Nitrogen deposition significantly increased soil respiration, but the positive effects of high-N treatment decreased over time. Meanwhile, N deposition significantly decreased both the soil temperature sensitivity (Q_10-soil) and air temperature sensitivity (Q_10-air) of soil respiration. Biochar amendment significantly increased soil respiration in the first and third years. However, only BC2 reduced Q_10-soil and Q_10-air. The effects of biochar amendment on soil respiration varied with the level of N deposition. Three-factor analysis of variance showed that N deposition, biochar amendment, and time all had significant effects on soil respiration. Our results indicate that biochar could not effectively inhibit the promotion effect of N deposition on soil respiration in T. grandis orchard but may reduce soil carbon emission caused by future climate warming.

25193. 题目: Soil stabilisation by water repellency under no-till management for soils with contrasting mineralogy and carbon quality
文章编号: N19082406
期刊: Geoderma
作者: Filipe Behrends Kraemer, Paul D. Hallett, Héctor Morrás, Lucas Garibaldi, Diego Cosentino, Matías Duval, Juan Galantini
更新时间: 2019-08-24
摘要: No-till soil management is common around the globe, but the impacts on soil structural quality varies depending on cropping practice and inherent soil properties. This study explored water repellency as a driver of soil stabilization, as affected by soil mineralogy, granulometry and organic carbon quality in three Mollisols and one Vertisol under no-till management and with different levels of cropping intensity. The studied soils were located along a west-east textural gradient in the northern part of the Pampean region of Argentina. Cropping intensity treatments evaluated in each one of the soils were: Poor Agricultural Practices (PAP) close to a monoculture, Good Agricultural Practices (GAP) involving a diverse crop rotation and more targeted inputs, and the soil in the surrounding natural environment (NE) as a reference. NE had the greatest aggregate stability (MWD) of all cropping intensities, with GAP being more stable than PAP for Mollisols and PAP being greater than GAP for the Vertisol. This trend matched the Repellency Index (R_index), with greater R_index associated with greater MWD, including the difference between the Mollisols and Vertisol. However, the persistence of water repellency, measured by the Water Drop Penetration Time (WDPT) test followed the trend NE > GAP>PAP regardless of soil type. The increases in R_index and MWD were related to higher intensification as measured by the Crop Sequence Index, and decreased with greater soybean occurrence in the sequence. Both WDPT and R_index were closely related to aggregate stability, particularly for Mollisols. These results highlight the importance of considering the inherent soil characteristics texture and mineralogy to understand aggregate stabilization mediated by water repellency. Good correlations between soil water repellency, organic carbon fractions and aggregate stability were found. Under no-till, crop rotations can be altered to increase soil stability by inducing greater water repellency in the soils. The findings suggest that water repellency is a major property influencing soil structure stabilization, thus providing a useful quality indicator.

25194. 题目: Drained organic soils under agriculture — The more degraded the soil the higher the specific basal respiration
文章编号: N19082405
期刊: Geoderma
作者: Annelie Säurich, Bärbel Tiemeyer, Axel Don, Sabine Fiedler, Michel Bechtold, Wulf Amelung, Annette Freibauer
更新时间: 2019-08-24
摘要: Drained peatlands are hotspots of carbon dioxide (CO₂) emissions from agricultural soils. As a consequence of both drainage-induced mineralisation and anthropogenic mixing with mineral soils, large areas of former peatlands under agricultural use underwent a secondary transformation of the peat (e.g. formation of aggregates). These soils show contents of soil organic carbon (SOC) at the boundary between mineral and organic soils. However, the carbon (C) dynamics of such soils have rarely been studied so far. The aim of the present study was to evaluate the vulnerability of soil organic matter (SOM) to decomposition over the whole range of peat-derived soils under agriculture including very carbon rich mineral soils (76–526 g kg⁻¹ SOC). A total of 62 soil samples covering a broad range of soil and site characteristics were selected from the sample set of the German Agricultural Soil Inventory. Potential CO₂ production was measured by aerobic incubation. Fen and bog peat samples were grouped into disturbance classes according to their soil properties. Specific basal respiration rates (SBR), i.e. CO₂ fluxes per unit SOC, showed the highest values for the most disturbed samples for both fen peat (13.9 ± 6.0 μg CO₂-C g SOC⁻¹ h⁻¹) and bog peat (10.9 ± 4.7 μg CO₂-C g SOC⁻¹ h⁻¹). Respiration rates of bog peat increased more strongly with an increasing degree of disturbance than those of fen peat. Perhaps counterintuitively, SOM vulnerability to decomposition thus increased with an increasing degree of disturbance and a decreasing SOC content, indicating positive feedback mechanisms as soon as peat soils are disturbed by drainage. Furthermore, the variability of the SBR increased drastically with increasing degree of disturbance. The turnover of SOM in less disturbed peat samples tended to be higher in samples with higher nitrogen (N) content, higher pH value and lower C:N ratio, while plant-available phosphorus was important for the mineralisation of more severely disturbed peat. However, clear correlations between a single soil property and SBR could not be identified. The high potential of CO₂ emissions from organic soils with a low SOC content implies that mixing organic soil with mineral soil does not seem to be a promising option for mitigating greenhouse emissions.

25195. 题目: Effects of laboratory biotic aging on the characteristics of biochar and its water-soluble organic products
文章编号: N19082404
期刊: Journal of Hazardous Materials
作者: Guixiang Quan, Qinya Fan, Andrew R. Zimmerman, Jianxiong Sun, Liqiang Cui, Hailong Wang, Bin Gao, Jinlong Yan
更新时间: 2019-08-24
摘要: Effects of biotic aging on the characteristics of biochar and its water-soluble organic products were determined through a one-year laboratory incubation study. Biochar had a positive influence on microbial population size. Without microbial addition, biochars showed little change, except for an obvious increase in oxygen content from 3.2% to 6.3% after one year. By contrast, the carbon (C) content of the biologically-aged biochars continually decreased throughout the incubation at two humidity levels, suggesting that microbes consumed biochar C or encouraged organic matter solubilization. Fourier Transform Infrared Spectroscopy (FTIR) analysis indicated that all aged biochar surfaces showed increases in oxygen-containing functional groups and TG-DTG analysis showed that biologically-aged biochars were less stable than the corresponding abiotically-aged one. The release of dissolved organic matters from biologically-aged biochar logarithmically increasing with time, corresponded with of the pattern of microbe production, suggesting microbial involvement in solubilizing biochar. Combined three-dimensional excitation-emission matrix (3DEEM) and parallel factor (PARAFAC) analyses revealed that fulvic and humic acid-like components were the main water-soluble products of biologically-aged biochar, and these became increasingly rich in O-containing functional groups, i.e. humified, over time. These results highlight the importance of microbes in chemically transforming biochar and the dissolved products of biochar during aging.

25196. 题目: Data-driven ENZYme (DENZY) model represents soil organic carbon dynamics in forests impacted by nitrogen deposition
文章编号: N19082403
期刊: Soil Biology and Biochemistry
作者: Yizhao Chen, Ji Chen, Yiqi Luo
更新时间: 2019-08-24
摘要: Soil microorganisms participate in almost all soil organic carbon (SOC) transformations, but they are not represented explicitly in the current generation of earth system models. This study used a data-driven approach to incorporate extracellular enzyme activity into the Terrestrial ECOsystem (TECO) model, and the updated version was named the Data-driven ENZYme (DENZY) model. DENZY is based on results from an extensive data synthesis, which show that the CN ratio is positively correlated with ligninase activity (R² = 0.50). The latter is inversely correlated to soil organic carbon storage. The DENZY model was parameterized using the database from a recent meta-analysis and tested for its ability to simulate SOC dynamics at Duke Forest (North Carolina, USA) from 1996 to 2007. DENZY can well simulate the observed negative relationship between ligninase activity and SOC under N deposition conditions (R² ranges from 0.61 to 0.89). Moreover, outputs from DENZY better matched the observed SOC than its prototype model with the same parameterization. This study provides a simple and straightforward approach to effectively use real-world observations to improve SOC projections in land biogeochemical models.

25197. 题目: Changes in soil physical and chemical characteristics in intensively cultivated greenhouse vegetable fields in North China
文章编号: N19082402
期刊: Soil and Tillage Research
作者: Jiangang Li, Xin Wan, Xiaoxiao Liu, Yong Chen, Lindsey C. Slaughter, David C. Weindorf, Yuanhua Dong
更新时间: 2019-08-24
摘要: The total area of greenhouse crop production is increasing in China. However, this adversely influences soil physical and chemical properties due to special environmental conditions and agricultural management in greenhouse production. In this study, we evaluated soil properties of greenhouse vegetable systems with different planting years, a long-term greenhouse strawberry system, and an open-field wheat-maize rotation system in a typical agricultural production area of North China. The annual fertilizer application rates of nitrogen (N), phosphorus (P), and potassium (K) in the greenhouse vegetable system were 842.15, 809.14, and 931.55 kg ha⁻¹, respectively, which were 3 times more than those in the wheat-maize rotation system and led to great changes of soil properties. Bulk density and soil pH gradually declined with increased cultivation time from new to 15 years in the greenhouse vegetable system. Bulk density declined from 1.58 g/cm³ in the new greenhouse fields to 1.25 g/cm³ in the 15-year greenhouse fields, and pH decreased from 5.72 to 4.55 with a rate of 0.08 unit per year. The contents of soil organic carbon (SOC), soil soluble salts, total NPK, and available NPK rose steadily until the 10th or 11th year, then decreased. By comparison with another two cropping systems, the greenhouse vegetable fields showed the lowest bulk density and pH, but the highest contents of SOC, soil soluble salts, total NPK, and available NPK due to heavy fertilizer inputs. The contents of soil N, P, and K in greenhouse vegetable fields were imbalanced, as indicated by C:N (11.58), C:P (16.06), and N:P (1.71) molar ratios in soils, which were significantly lower than the level in China and the rest of the world. In addition, the C:P and N:P ratios of greenhouse vegetable fields were also lower than those of wheat-maize rotation fields and greenhouse strawberry fields. Regression analysis indicated that the contents of SOC and soluble salts were positively correlated with pH, while available N and P contents showed negative linear relationships. These results demonstrate dramatic adverse changes of soil properties in intensive greenhouse vegetable fields in China. Our results also emphasize the need to regulate appropriate fertilizer application for intensive greenhouse vegetable management.

25198. 题目: Degradation and DBP formations from pyrimidines and purines bases during sequential or simultaneous use of UV and chlorine
文章编号: N19082401
期刊: Water Research
作者: Xinran Zhang, Jiaxin Zhai, Yu Zhong, Xin Yang
更新时间: 2019-08-24
摘要: Purine and pyrimidines are present an important pool of dissolved organic nitrogen in aqueous medias and also precursors of disinfection byproducts. The degradation kinetics of cytosine and adenine—model pyrimidine and purine compounds—were investigated along with their transformation pathways leading to the formation of disinfection byproducts during two typical multi-barrier disinfection processes: UV irradiation and UV/chlorine pretreatment followed by post-chlorination. UV irradiation followed by post-chlorination enhanced the degradation of cytosine and adenine (by 17.1 and 26.1%, respectively), but it also generated more byproduct precursors compared to chlorination alone. The presence of reactive species in the UV/chlorine treatment greatly enhanced cytosine and adenine degradation (by 61.8 and 123.0%) but generated even more disinfection byproducts. Compared to 24 h chlorination, the concentrations of byproducts increased by up to 361.6% for cytosine and 85.1% for adenine with longer UV/chlorine treatment (from 2 to 30 min). Thirty minutes of combined UV/chlorine treatment decreased the total organic chlorine produced from cytosine by 34.4% (from 233.8 to 153.3 μg Cl L⁻¹) but it increased byproduct generation by 68.3% compared with 24 h of simple chlorination. The TOCl from adenine increased by 50.0% (from 9.2 to 18.4 μg Cl L⁻¹) but byproduct generation was 11.0% less after 30 min of UV/chlorine pretreatment followed by 24 h of chlorination. The intermediates generated were analyzed in detail and multiple transformation pathways leading to byproduct formation are proposed.
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25199. 题目: Environmentally Persistent Free Radical (EPFR) Formation by Visible-Light Illumination of the Organic Matter in Atmospheric Particles
文章编号: N19082308
期刊: Environmental Science & Technology
作者: Qingcai Chen, Haoyao Sun, Mamin Wang, Yuqin Wang, Lixin Zhang, Yuemei Han
更新时间: 2019-08-23
摘要: A secondary process may be an important source of environmentally persistent free radicals (EPFRs) in atmospheric particulates; yet, this process remains to be elucidated. This study demonstrated that secondary EPFRs could be generated by visible-light illumination of atmospheric particulate matter (PM), and their lifetimes were only 30 min to 1 day, which were much shorter than the lifetimes of the original EPFRs in PM. The yields of secondary EPFRs produced by PM could reach 15–60% of those of the original EPFRs. The extractable organic matter contributed to the formation of secondary EPFRs (∼55%), and a humic-like substance was the main precursor of the secondary EPFRs and was also the most productive precursor compared to the other aerosol components. The results of simulation experiments showed that the secondary EPFRs generated by the extractable and nonextractable PM components were similar to those produced by phenolic compounds and polycyclic aromatic hydrocarbons, respectively. We have found that oxygen molecules play an important role in the photochemical generation and decay of EPFRs. The reactive oxygen capture experiments showed that the original EPFRs may contribute to singlet oxygen generation, while the secondary EPFRs generated by photoexcitation may not produce singlet oxygen or hydroxyl radicals.

25200. 题目: The global soil community and its influence on biogeochemistry
文章编号: N19082307
期刊: Science
作者: T W Crowther, J van den Hoogen, J Wan, M A Mayes, A D Keiser, L Mo, C Averill, D S Maynard
更新时间: 2019-08-23
摘要: Soils harbor a rich diversity of invertebrate and microbial life, which drives biogeochemical processes from local to global scales. Relating the biodiversity patterns of soil ecological communities to soil biogeochemistry remains an important challenge for ecologists and earth system modelers. Crowther et al. review the state of science relating soil organisms to biogeochemical processes, focusing particularly on the importance of microbial community variation on decomposition and turnover of soil organic matter. Although there is variation in soil communities across the globe, ecologists are beginning to identify general patterns that may contribute to predicting biogeochemical dynamics under future climate change.Science, this issue p. eaav0550BACKGROUNDSoil is the largest repository of organic matter on land, storing ~1500 Gt carbon, which is at least as much as the vegetation (~560 Gt) and atmosphere (~750 Gt) combined. The turnover of this organic material (the rate at which it enters and leaves the soil) is governed by the most diverse community on Earth. By determining the rate and biochemical pathway of organic matter processing, fungi, bacteria, archaea, animals, and protists regulate soil fertility, plant growth, and the climate. Given their roles in regulating the exchanges of elements between terrestrial and atmospheric pools, the effective management of this soil community is among our most powerful weapons in the fight against the global threats of biodiversity loss and climate change. However, despite the critical importance of these organisms, the hyperdiverse nature of local soil communities has traditionally obscured efforts to identify general global patterns. As such, environmental factors have traditionally been used as proxies to represent the variation in soil functioning across landscapes. But it is the organisms{ extemdash}not only the environment{ extemdash}that directly drive the turnover of organic material. Given that different organisms have varying impacts on elemental cycling, exploring the functional biogeography of soil communities is likely to be critical for improving confidence in global biogeochemical model predictions.ADVANCESOver the past decade, a growing body of evidence highlights that regional differences in the soil community drive considerable variation in biogeochemistry. Just as the transition from forests to grasslands drive vast differences in ecosystem functioning, differences in the structure of soil communities can drive enormous variation in elemental cycling. By expanding our horizons to see beyond the complexity of local soil communities, ecologists have begun to identify general patterns in the biomass, composition, and diversity of soil communities. Despite the immense diversity of these organisms, the global soil community appears to be dominated by a manageable number of groups, which are likely to play a prominent role in the regulation of soil biogeochemistry. The metabolic activity and species richness of most soil organisms generally increase toward warm, moist tropical regions, where rapid elemental cycling depletes soil carbon relative to the higher latitudes. In addition, the huge accumulation of organic matter stocks in cold Arctic and sub-Arctic regions leads to huge abundances of soil microbes and animals at high latitudes. These global trends reveal key insights into the biological mechanisms that drive the distribution of organic matter on land as well as the vulnerability of different carbon stocks to future global change. Each new layer of global ecological information reveals distinct biogeographic patterns that provide insights into the fundamental distribution and dynamics of organic matter on land.OUTLOOKThe field of soil ecology continues to uncover critical mechanisms that govern the turnover of organic matter at local scales. But placing these mechanisms into context necessitates that we continue to expand our understanding of the global biogeography of soil organisms. These communities can be viewed at multiple levels of ecological resolution, starting from the biomass of overall communities, which can then be divided into different functional groups, taxa, and functional traits. As we move down this list, we gain mechanistic detail at the expense of predictive understanding. While we continue to refine our detailed understanding of microbial taxa and trait compositions, we also need to step back to characterize the biomass distributions of the major functional groups of soil organisms, which reflect considerable differences in biogeochemical processing rates. As we generate this global ecological data, sensitivity analyses will then be necessary to identify the mechanisms that are most critical for improving biogeochemical model performance. These insights have the potential to improve predictions of soil fertility, plant production, and the climate. Ultimately, this emerging perspective of the most diverse and abundant community on land will provide fundamental insights into the organization of life on Earth.Latitudinal trends in organic matter across terrestrial ecosystems.(A) The latitudinal patterns of terrestrial carbon stocks, both aboveground plant biomass (green) and soil carbon stocks (brown). (B) The same latitudinal trend in soil microbial biomass, revealing similar patterns to that observed in soil carbon. (Data sources are provided in Fig. 2 in the main text.)Soil organisms represent the most biologically diverse community on land and govern the turnover of the largest organic matter pool in the terrestrial biosphere. The highly complex nature of these communities at local scales has traditionally obscured efforts to identify unifying patterns in global soil biodiversity and biogeochemistry. As a result, environmental covariates have generally been used as a proxy to represent the variation in soil community activity in global biogeochemical models. Yet over the past decade, broad-scale studies have begun to see past this local heterogeneity to identify unifying patterns in the biomass, diversity, and composition of certain soil groups across the globe. These unifying patterns provide new insights into the fundamental distribution and dynamics of organic matter on land.