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101. 题目: P-nitrophenol degradation by pine-wood derived biochar: The role of redox-active moieties and pore structures
文章编号: N20063003
期刊: Science of the Total Environment
作者: Shihui Feng, Peng Zhang, Wenyan Duan, Hao Li, Quan Chen, Jing Li, Bo Pan
更新时间: 2020-06-30
摘要:

Biochar can both adsorb and degrade p-nitrophenol (PNP); however, the PNP degradation mechanism has not been well investigated. We prepared two biochars at pyrolysis temperatures of 500 °C (B500) and 700 °C (B700). Although B500 showed much stronger free radical signals (which are associated with organic degradation, according to previous studies), the apparent PNP degradation was approximately 3 times higher in the B700 system. The degradation increased significantly after the biochars were washed with water. According to a quantitative analysis of the sorption and degradation and two-compartment first-order kinetics modeling of the apparent removal kinetics, sorption occurred mainly in the initial period, whereas degradation continued throughout the removal process. The PNP degradation rate constant depended mainly on the external surface area at a relatively low concentration (200 mg/L) and was controlled by the microporous surface area at a relatively high concentration (800 mg/L). In addition, the apparent degradation did not depend on the biochar particle size. Therefore, PNP degradation may be related to the three-dimensional structure of the biochar in addition to the exposed external surface. The well-developed pore structure, more accessible surface, and larger electron exchange capacity of B700 may promote electron transfer between the biochar and PNP, and thus accelerate PNP degradation. This study demonstrates that various properties of the biochar may contribute to PNP degradation.

102. 题目: Optimization of the Coagulation–Flocculation Process for Slaughterhouse Wastewater Using Response Surface Methodology
文章编号: N20063002
期刊: Clean - Soil, Air, Water
作者: Öznur Begüm Gökçek, Safiye Özdemir
更新时间: 2020-06-30
摘要:

Slaughterhouse wastewater is one of the main sources of environmental pollutants, containing a high amount of organic matter (chemical oxygen demand (COD), biochemical oxygen demand (BOD)), total nitrogen, total suspended solids, total phosphorus, grease, and oil. The main aim of the present research is optimizing the coagulation–flocculation process and examining the effects of experimental factors with each other, e.g. pH, the concentration of two different coagulants (FeCl3 and alum), rapid mixing rate, and settling time. Therefore, it is aimed to treat slaughterhouse wastewater using the coagulation–flocculation process with the optimization of the response surface methodology (RSM). COD, turbidity, and suspended solids (SS) of the treated wastewater were chosen as the response variables. Furthermore, the optimal conditions for three responses were acquired by employing the desirability function approach. When the experimental results of two coagulants were compared, it was observed that the alum coagulant gave better results for the three responses. The alum coagulant utilized in the present research was able to increase COD, SS, and turbidity removal efficiency by 75.25, 90.16, and 91.18%, respectively. It is possible to optimize coagulation–flocculation by utilizing the RSM analysis, which proves that coagulation can pre‐treat slaughterhouse wastewater.

This article is protected by copyright. All rights reserved

103. 题目: Effects of humus on the mobility of arsenic in tailing soil and the thiol-modification of humus
文章编号: N20063001
期刊: Chemosphere
作者: Yunfeng Xu, Kaili Wang, Qinghao Zhou, Liting Zhang, Guangren Qian
更新时间: 2020-06-30
摘要:

The ability of thiol-modified humic acids (HAs) to release arsenic in tailings soil after being modified with different sulfur-containing reagents were significantly improved. The structure and physicochemical properties of humic acid (HA) before and after thiol-modification were characterized. The 3-MPTS-HA treated with 3-mercaptopropyltrimethoxysilane (3-MPTS) effectively improved the mobility of arsenic, and its reducing ability was increased from 2 mmol g−1 to 3.54 mmol g−1. The S content of humic acids were also significantly increased after treatment with sulfur-containing reagents, in which the oxygen-containing functional group (e.g., C = O, C–O) on the surface of HA may be the active sites for binding with sulfur-containing reagents. It was found in the XPS spectrum that because the thiol group is easily oxidized, there are many S forms in thiol-modified HA. The –SH content in Na2S·9H2O-HA, l (+)-Cysteine-HA (Cys-HA), thioglycolic acid (TGA-HA) and 3-MPTS-HA was determined by fluorescence method to be 13.9, 78.45, 90.34, and 192.29 μmol g−1, respectively. The study demonstrated that surface thiol modification can increase the abundance of thiol in HA and enhance reactivity, which will further promote the application of HA in the treatment of heavy metal contaminated tailing soil.

104. 题目: Identifying key drivers for geospatial variation of grain micronutrient concentrations in major maize production regions of China
文章编号: N20062905
期刊: Environmental Pollution
作者: Qing-Yue Zhao, Shi-Jie Xu, Wu-Shuai Zhang, Zhe Zhang, Zhi Yao, Xin-Ping Chen, Chun-Qin Zou
更新时间: 2020-06-29
摘要:

Micronutrient deficiencies are prevalent health problems worldwide. The maintenance of adequate concentrations of micronutrients in maize grain is crucial for human health. We investigated the overall status and geospatial variation of micronutrients in Chinese maize grains and identified their key drivers. A field survey was conducted in four major maize production areas of China in 2017 with 995 pairs of soil and grain samples collected from famers' fields. At a national scale, grain zinc (Zn), iron (Fe), manganese (Mn) and copper (Cu) concentrations varied substantially, with average values of 17.4, 17.3, 4.9, and 1.5 mg kg−1, respectively, suggesting a solid gap between grain Zn and Fe concentrations and the biofortification target values. Significant regional difference in the concentrations of Zn, Mn and Cu, but not Fe, were observed in grain, with much higher levels in Southwest China. The nutritional yields of Zn, Fe and Cu were lower than the energy and Mn yields, indicating an unbalanced outcome between energy and micronutrients in current maize production system. Grain Zn, Fe, Mn and Cu correlated negatively with maize yield in most test regions. Increased nitrogen (N) rate positively affected grain Zn and Cu, while increased phosphorus (P) rate negatively affects grain Zn and Fe. Apart from Fe, available Zn, Mn and Cu in soil exerted significant positive effects on grain Zn, Mn and Cu concentrations, respectively. Decrease in soil pH and increase in the organic matter content may increase the accumulation of Fe and Mn in grain. Grain Zn and Cu concentrations increased as available soil P decreased. Of the factors considered in this study, grain yield, N and P rates, soil pH and organic matter were the main factors that affect grain micronutrient status and should be more extensively considered in the production and nutritional quality of maize grain.

105. 题目: Red mud modified sludge biochar for the activation of peroxymonosulfate: Singlet oxygen dominated mechanism and toxicity prediction
文章编号: N20062904
期刊: Science of the Total Environment
作者: Jia Wang, Min Shen, Hailong Wang, Yusheng Du, Xinquan Zhou, Zhuwei Liao, Huabin Wang, Zhuqi Chen
更新时间: 2020-06-29
摘要:

In this paper, red mud-sewage sludge derived biochar (RSDBC) was synthesized and employed as the heterogenous activator of peroxymonosulfate (PMS) for sulfamethoxazole (SMX) degradation. With the incorporation of red mud, 82.5% degradation of SMX was achieved by RSDBC/PMS system in a process dominated by 1O2, which was attributed to the participation of oxygen vacancy, ketone groups and graphitic carbon. On the other hand, in the absence of red mud, OH and SO4•− were dominantly accounted for SMX degradation in sewage sludge derived biochar (SDBC)/PMS system. In this case heterogeneous Fe species, ketone groups and graphitic carbon were responsible for PMS activation. Due to the different Reactive Oxygen Species (ROS), effects of reaction conditions including initial pH, common anions and natural organic matter (NOM) were not in full accord. Besides, Fe leaching from RSDBC (0.67 ppm) was much lower than that of SDBC (3.07 ppm), leading to a better reuse ability for RSDBC. Less degradation intermediates were disclosed in RSDBC/PMS system, along with lower residual toxicity. In addition, eco-toxicity of all the intermediates was predicted by ECOSAR program for the further understanding of the detoxification of SMX. Advantages of RSDBC/PMS system as disclosed in this paper further suggest its potential full-scale application of environmental remediation.

106. 题目: Recycling application of waste long-root Eichhornia crassipes in the heavy metal removal using oxidized biochar derived as adsorbents
文章编号: N20062903
期刊: Bioresource Technology
作者: Sen Lin, Weiwei Huang, Hongjun Yang, Shuying Sun, Jianguo Yu
更新时间: 2020-06-29
摘要:

An oxidized biochar was prepared using long-root Eichhornia crassipes through an aerobic/anaerobic hybrid calcination to recycle its waste plants after eutrophic treatments. The adsorption performances of the biochar were investigated and the results showed that the adsorption equilibrium could arrive in 30 min and the adsorption capacities for Pb2+, Cu2+, Cd2+ and Zn2+ at 30°C were 0.57, 0.41, 0.44 and 0.48 mmol/g, respectively. The adsorption could be promoted at higher pH and temperature and the adsorption tolerance for different heavy metal ions to the existence of competing ions and organic matters was hierarchical. The adsorption was deduced to be heterozygous courses and mainly controlled by complexation of oxygen-containing groups with these heavy metal ions. It was confirmed that the biochar could be regenerated with HCl solution and the adsorption performance kept consistent in 10 adsorption-desorption cycles.

107. 题目: Soil Organic Matter Dynamics as Affected by Land Use Change from Rice Paddy to Wetland
文章编号: N20062902
期刊: Wetlands
作者: Xian Wu, Toan Nguyen-Sy, Zheng Sun, Toru Wantanabe, Keitaro Tawaraya, Ronggui Hu, Weiguo Cheng
更新时间: 2020-06-29
摘要: The objective of this study was to investigate the impact of land use change, from rice paddy to natural wetland, on soil organic matter dynamics 12 years after the former was abandoned. Cold water extracted organic carbon (CWEOC) and hot water extracted organic carbon (HWEOC) obtained from surface and subsurface soil layers were measured as important indexes, reflecting organic matter dynamics. The quality of CWEOC and HWEOC was characterized by UV absorbance and parallel factor analysis (PARAFAC) modeling of fluorescence excitation-emission matrices (FEEMs). The results showed the land use change didn't significantly alter the quantity of SOC in all layer, but decrease the concentrations of CWEOC and HWEOC whereas the δ13C values appeared to increase. It suggested the carbon input into soil induced the change of DOC. The SUVA254 results showed aromatic content of DOC was less abundant in rice paddy, indicating DOC from paddy soil is more labile. The FEEM analysis suggested extracts from the rice paddy surface and wetland subsurface layers contain more humic-like fluorophores, while higher abundances of the tryptophan-like fluorophore were found in rice paddy subsurface and wetland surface layers. Overall, converting rice paddy to wetland didn't alter the stock of SOC; however, it significantly decreased the stock and stability of dissolved organic carbon.

108. 题目: Variation in the properties of biochars produced by mixing agricultural residues and mineral soils for agricultural application
文章编号: N20062901
期刊: Waste Management and Research
作者: Stella Cristiani Gonçalves Matoso, Paulo Guilherme Salvador Wadt, Valdomiro Severino de Souza Júnior, Xosé Lois Otero Pérez, Fábio Plotegher
更新时间: 2020-06-29
摘要: The research and application of biochars enriched with minerals have increased in recent years; however, the mineral fraction used consists of specific minerals, such as clay minerals and synthesized compounds. In this work, the effects of adding two specific soil types (sandy and clayey) to rice and coffee husks in order to generate biochars via pyrolysis was investigated. Chemical, physical–chemical, thermal, spectroscopic and crystallographic analyses were conducted on the produced biochars. The study confirmed that the presence of mineral soils during the pyrolysis process increases the yield, C retention ratio, and specific surface area. It also decreases the pH, cation exchange capacity (CEC), nutrient content, and carbon-to-nitrogen ratio of biochars. However, the biochars produced by mixing coffee husks and mineral soils still demonstrate a capacity to increase the pH and the CEC of tropical soils. In addition, increased C retention demonstrates an environmental benefit of this biochar production method. Biomass pyrolysis combined with clayey soil results in a biochar with a higher degree of aromaticity and higher thermal stability when compared to biomass pyrolysis alone. These characteristics give the biochar a recalcitrant character, without the necessity for steps related to the synthesis of specific mineral compounds, which reduces the economic and energy cost of the process.

109. 题目: KMnO4-mediated reactions for hexachlorophene in aqueous solutions: Direct oxidation, self-coupling, and cross-coupling
文章编号: N20062814
期刊: Chemosphere
作者: Wanming Cao, Yao Yu, Junyan Wei, Ghada Al-Basher, Xiaoxue Pan, Beibei Li, Xinxin Xu, Nouf Alsultan, Jing Chen, Ruijuan Qu, Zunyao Wang
更新时间: 2020-06-28
摘要:

Hexachlorophene (HCP) is used in a range of general cleaning and disinfecting products and has received increased attention due to its damaging effect to the central nervous system in animals and its toxicity in humans. The chemical oxidation of HCP by KMnO4 was performed to systematically evaluate the effects of oxidant dose, pH, temperature, typical anions, humic acid (HA), and various matrices on HCP removal. The second-order rate constant for HCP was determined to be 4.83 × 104 M−1 s−1 at pH 7.0 and 25 °C. The presence of HA can inhibit the removal of HCP by KMnO4, while Cl, NO3, SO42−, PO43−, and CO32− have negligible effects. Degradation products analysis of the reaction, as well as theoretical calculations of HCP molecule and its phenoxy radical species, indicated that KMnO4 oxidation for HCP included a C–C bridge bond cleavage, hydroxylation, direct oxidation and self-coupling, and cross-coupling reactions. This study revealed that KMnO4 oxidation is an effective technique for eliminating HCP in real water and wastewater.

110. 题目: The Rock-Eval® signature of soil organic carbon in arenosols of the Senegalese groundnut basin. How do agricultural practices matter?
文章编号: N20062813
期刊: Agriculture, Ecosystems and Environment
作者: Oscar Pascal Malou, David Sebag, Patricia Moulin, Tiphaine Chevallier, Ndeye Yacine Badiane-Ndour, Abou Thiam, Lydie Chapuis-Lardy
更新时间: 2020-06-28
摘要:

Soil organic carbon (SOC) ensures soil quality and productivity of cultivated systems in the Sahelian region. This study uses Rock-Eval® pyrolysis to examine how cultural practices impact the quantity of SOC and quality of SOM in cultivated sandy soils in the Senegal groundnut basin. This cost-effective method provides information on SOC thermal stability, which has been shown to be related qualitatively to biogeochemical stability of SOC. We sampled soils within two villages in agricultural plots representative of local agricultural systems, and in two local preserved areas (tree plantation and shrubby savanna). SOC concentrations ranged from 1.8–18.5 g.kg−1 soil in the surface layer (0−10 cm) and from 1.5–11.3 g.kg−1 soil in the 10−30 cm layer. SOC contents of cultivated soils decreased significantly (p-value < 0.0001) according to field amendment, in the following order: addition of organic wastes> addition of manure > millet residues left after harvest > no organic input. We found that the quantity and the quality of SOC are linked, and that both depend on land-use and agricultural practices, especially upon the type of organic inputs. Quantity of SOC and quality of SOM are correlated strongly in the tree plantation (R² = 0.98) and in the protected shrubby savanna (R² = 0.97). They are also correlated significantly in cultivated soils receiving organic wastes (R² = 0.82), manure (R² from 0.74 and 0.91), or millet residues (R2 = 0.91) but not in soils that receive no organic inputs. Indexes based upon Rock-Eval® pyrolysis were represented in an I/R diagram that illustrates the level of SOC stabilization. The indexes of the studied soils were plotted against comparable results from literature. Thermal signatures of the Senegalese Arenosols show an inversion of I and the R indexes compared to data from the literature. This result highlights SOC stabilization as a function of soil depth. Indeed, the refractory pool in the studied soils (where refractory pool ranged from 7.7–21.3 % in the 0−10 cm layer, and from 12.5–24.3 % in the 10−30 cm) was more abundant than in Ferralsols in natural conditions, where refractory pool ranged from 2 to 9%. The soil organic matter in these Arenosols while positively affected by organic inputs, is dominated by more or less labile forms that mineralize quickly: a quality that is excellent for productivity of these agrosystems, but not for mitigation of climate change in the long term.

111. 题目: Removal of legacy PFAS and other fluorotelomers: Optimized regeneration strategies in DOM-rich waters
文章编号: N20062812
期刊: Water Research
作者: Fuhar Dixit, Benoit Barbeau, Shadan Ghavam Mostafavi, Madjid Mohseni
更新时间: 2020-06-28
摘要:

We present the first study investigating optimized regeneration strategies for anionic ion exchange (IX) resins during the removal of persistent per- and poly-fluoroalkyl substances (PFAS, including GenX) from surface and treated wastewater effluents. IX regeneration studies are of critical importance from environmental perspectives. Specifically, the knowledge is essential for water utilities who presently operate IX (for PFAS removal) in a single use-and-dispose mode. In this study, legacy PFAS such as PFOA/PFOS were tested along with other harmful short-chained PFAS (PFBA/PFBS) and other toxic perfluorinated substitutes (GenX). Studies were performed on synthetic water (spiked with Suwannee River Natural Organic Matter (SRNOM), Fulvic Acid (SRFA) and Humic Acid (SRHA)), surface water, and wastewater effluents, and the regeneration was performed in batch stirred reactors. The resin service life with and without regeneration was investigated in the presence of background organic matter. In ultra-pure waters, all PFAS (C0 ∼10 μg/L, concentrations similar to that of natural waters) were effectively removed for >100,000 Bed Volume (BV) of operation. This was reduced to ∼23,500 BV in the presence of SRNOM (C0 = 5 mg C/L), 20,500 BV in SRFA and 8500 BV in SRHA, after which the saturated resins required regeneration. More importantly, all resin breakthrough (PFAS> 70 ng/L) corresponded to > 90% resin site saturation (in meqs), an essential information for optimizing IX loading. The competitive dissolved organic matter (DOM) fractions were estimated to be approximately 5–9% of the initial DOC, as estimated by the IAST-EBC model. Finally, it was identified that IX regeneration efficiency improved with increasing brine contact time but effectiveness plateaued for brine concentrations above 10% (W/V). Nonetheless, a regeneration with 10% NaCl solution with a contact time of 2 h was found to be optimal for IX operations in synthetic and natural waters. Therefore, this study provides key knowledge essential for the scientific community and the water industry on optimizing IX operational parameters for DOM and PFAS removal and would be highly valuable for systems which presently operate IX in a use-and-dispose mode.

112. 题目: Combined application of modified corn-core powder and sludge-based biochar for sewage sludge pretreatment: Dewatering performance and dissipative particle dynamics simulation
文章编号: N20062811
期刊: Environmental Pollution
作者: Zhiying Guo, Liping Ma, Quxiu Dai, Ran Ao, Hongpan Liu, Jie Yang
更新时间: 2020-06-28
摘要:

Sludge is an inevitable by-product of municipal wastewater treatment processes, and its high moisture content poses a major challenge for its subsequent treatment and disposal. Previous studies have explored the effects of applying modified corn-core powder (MCCP) on dewatering sludge. Here, we characterized the effects of applying both MCCP and sludge-based biochar (SBB) on dewatering sludge. Analysis of the anti-shear ability of SBB revealed that SBB was a skeleton builder with high compressive strength, demonstrating that SBB could maintain the permeability of sludge under high-pressure filtration processes and facilitate the flow of bound water. Dissipative particle dynamics (DPD) was used to simulated the sludge flocculating process and verify the feasibility of the experiment. As the simulation progressed, the reaction in the sludge network reached equilibrium and the simulated structure of the sludge became loose. The dewatering performance and physicochemical properties of the treated sludge were studied to further characterize the effect of this combined technology. Compared with MCCP-sludge, MCCP&SBB-sludge, which was treated by 20% DS (mass of dry solids in sludge) of SBB and 20% DS of MCCP, achieved superior dewaterability. This combined method reduced the specific resistance of filtration by 76% and enlarged the net sludge solids yield by 138%. Further study of the properties of MCCP&SBB-sludge revealed a loose structure that resembled the structure recovered by the simulation, suggesting that the DPD simulation method simulated the sludge flocculating process successfully. Therefore, the combined application of MCCP and SBB was superior for sludge dewatering because of the synergistic effects of MCCP and SBB.

113. 题目: Activation of percarbonate by water treatment sludge–derived biochar for the remediation of PAH-contaminated sediments
文章编号: N20062810
期刊: Environmental Pollution
作者: Chang-Mao Hung, Chin-Pao Huang, Chiu-Wen Chen, Chung-Hsin Wu, Yi-Li Lin, Cheng-Di Dong
更新时间: 2020-06-28
摘要:

Sludge from a groundwater treatment plant was used to prepare biochar by pyrolysis. The Fe–Mn rich biochar was used to activate percarbonate for the remediation of polycyclic aromatic hydrocarbons (PAHs) contaminated aquatic sediments. Results showed that the sludge–derived biochar (SBC) produced at a pyrolysis temperature of 700 °C was the most effective in activating percarbonate, which exhibited significant oxidative removal of PAHs. PAHs degradation took place via a Fenton-like oxidation manners, contributed from the Fe3+/Fe2+ and Mn3+/Mn2+ redox pairs, and achieved the highest degradation efficiency of 87% at pH0 6.0. Reactions between oxygenated functional groups of biochar and H2O2 generated of O2•– and HO• radicals in abundance under neutral and alkaline pH was responsible for the catalytic degradation of PAHs. Our results provided new insights into the environmental applications of SBC for the green sustainable remediation of organics-contaminated sediments and aided in reduction of associated environmental and health risk.

114. 题目: Co-pyrolysis of sewage sludge and biomass in carbon dioxide as a carrier gas affects the total and leachable metals in biochars
文章编号: N20062809
期刊: Journal of Hazardous Materials
作者: Magdalena Kończak, Patryk Oleszczuk
更新时间: 2020-06-28
摘要:

The total and available (water extracted) content of selected metal were determined in co-pyrolyzed SSL with willow (8:2, 6:2 w/w) at 500, 600, and 700 °C using two different carrier gases (N2 or CO2). The study investigated the relationship of metal content and bioavailability to toxicity of biochars towards bacteria (Vibrio fischeri), plants (Lepidium sativum), and arthropods (Folsomia candida).

For the biochar produced at a ratio of 6:4 (SSL:willow), the content of most metals significant decrease (P ≤ 0.05) from 5.9% to 28.9%. Co-pyrolysis of SSL with willow decreased water extractable metal concentrations (Ba, Cd, Cu, Fe, Mn, Ni, and Zn) from 8.0% to 100%. The CO2 resulted from 6 to 200 % increase (P ≤ 0.05) of metal content relative to the biochar pyrolyzed in N2. An increase in pyrolysis temperature caused a higher concentration of the metals in the biochars. The available content of most metals decreased from 9 to 100 %. The adverse effect of these biochars on living organisms was reduced due to a stronger binding of the metals (especially Cu and Cd) with the biochar matrix. The negative impact of Cd, Cr, and Cu on living organisms was also confirmed by principal component analysis (PCA).

115. 题目: Soil properties rather than climate and ecosystem type control the vertical variations of soil organic carbon, microbial carbon, and microbial quotient
文章编号: N20062808
期刊: Soil Biology and Biochemistry
作者: Tingting Sun, Yugang Wang, Dafeng Hui, Xin Jing, Wenting Feng
更新时间: 2020-06-28
摘要:

Small changes in soil organic carbon (SOC) may have great influences on the climate-carbon (C) cycling feedback. However, there are large uncertainties in predicting the dynamics of SOC in soil profiles at the global scale, especially on the role of soil microbial biomass in regulating the vertical distribution of SOC. Here, we developed a database of soil microbial biomass carbon (SMBC), SOC, and soil microbial quotient (SMQ = SMBC/SOC) from 289 soil profiles across five continents, as well as climate, ecosystem types, and edaphic factors associated with these soil profiles. We assessed the vertical distribution patterns of SMBC and SMQ and the contributions of climate, ecosystem type, and edaphic condition to their vertical patterns. Our results showed that SMBC and SMQ decreased exponentially with soil depth, especially within the 0–40 cm soil depth. SOC also decreased exponentially with depth but in different magnitudes compared to SMBC and SMQ. Edaphic factors (e.g., soil clay content and C/N ratio) had the strongest control on the vertical distributions of SMBC and SMQ, probably by mediating substrate and nutrient supplies for microbial growth in soils. Mean annual temperature and ecosystem types (i.e., forests, grasslands, and croplands) had weak influences on SMBC and SMQ. In contrast, the vertical distribution of SOC was significantly affected by climate and edaphic factors. Climate and ecosystem types likely simultaneously affected multiple factors that control SMBC, such as the distribution of soil clay and nutrients along soil profiles. Overall, our data synthesis provides quantitative information of how SMBC, SMQ, and SOC changed along soil profiles at large spatial scales and identifies important factors that influence their vertical distributions. The findings can help improve the prediction of C cycling in terrestrial ecosystems by incorporating the contribution of soil microbes in Earth system models.

116. 题目: High dissolved organic radiocarbon in precipitation during winter and its implication on the carbon cycle
文章编号: N20062807
期刊: Science of the Total Environment
作者: Ji-Yeon Cha, Seung-Cheol Lee, Eun-Ju Lee, Minjung Go, Kishore Babu Dasari, Yong-Hyeon Yim, Neung-Hwan Oh
更新时间: 2020-06-28
摘要:

Radiocarbon (14C) analysis is a powerful tool for tracing carbon in the global carbon cycle. Precipitation is a component of the global carbon cycle through which dissolved organic carbon (DOC) enters terrestrial and aquatic ecosystems from the atmosphere. In previous studies, the Δ14C of DOC in rain or snow was negative indicating an input of relatively old organic carbon including fossil fuels, with only a few positive values up to +108‰ showing the signal of recent photosynthesis. However, here we report surprisingly high Δ14C-DOC in bulk precipitation, more than 1000‰ in Seoul, South Korea, especially when the Northwesterly wind blows during winter. In contrast, Δ14C of particulate organic carbon (POC) in bulk precipitation was negative, indicating that the sources of POC and DOC were different. Although the sources of the high Δ14C-DOC are not clear and future studies on them are required, the relatively high Δ14C-DOC in a nearby headwater stream suggests that precipitation DOC has the potential to affect the local carbon cycle, and that stream DOC derived from terrestrial ecosystems could be older than previously thought. The analysis of Δ14C-DOC of precipitation in many other locations is necessary to understand how long carbon stays in terrestrial ecosystems.

117. 题目: Insight into the mechanism of low molecular weight organic acids-mediated release of phosphorus and potassium from biochars
文章编号: N20062806
期刊: Science of the Total Environment
作者: Huiying Zhang, Qingyang Li, Xia Zhang, Weifeng Chen, Jinzhi Ni, Liuming Yang, Ran Wei
更新时间: 2020-06-28
摘要:

A crucial mechanism for the application of biochar in soil improvement is the direct release of nutrients from biochar. Low molecular weight organic acids (LMWOAs) ubiquitously exist in soil. However, the mechanism of LMWOAs-mediated release of nutrients from biochars remains little known. Ten biochars with different mineral element stoichiometric ratio were produced, and four LMWOAs [acetic (HAc), glycolic (GA), tartaric (TA), and citric acids (CA)] were employed, to enunciate the influence mechanism of LMWOAs on the release of phosphorus and potassium from biochar. The results showed that HAc suppressed the release of P from biochars, while TA and CA facilitated the release of P from biochars with high ratios of polyvalent metals to P. A new mechanism was proposed that the deprotonated HAc combined with the dissolved HPO42− or H2PO4 to form a complex through hydrogen bond and cation bridging. The hydrophobic methyl group of HAc was exposed outside of the complex, which decreased the water-solubility of phosphate. Meanwhile, a high ratio of polyvalent metals to P benefited more P to combine with polyvalent metals, which decreased the water-solubility of P, but the deprotonated TA and CA are polyvalent anions that could substitute this part of P by anion exchange. Also, LMWOAs promoted the release of K from biochars with low K/(P + S) ratios, possibly due to unionized carboxyl of LMWOAs served as a hydrogen bond donor to displace K out of biochars. This study gives a deep understanding of the fate of biochar originated nutrients response to LMWOAs.

118. 题目: Comprehensive evaluation of dissolved organic matter molecular transformation in municipal solid waste incineration leachate
文章编号: N20062805
期刊: Chemical Engineering Journal
作者: Weiming Chen, Chen He, Xiaocun Zhuo, Fan Wang, Qibin Li
更新时间: 2020-06-28
摘要:

Transformations of the molecular compositions of dissolved organic matter (DOM) in incineration leachate (IL) were investigated. Results revealed that DOM in IL had a lower oxidation degree than that in mature MSW landfill leachate (LL). Moreover, aliphatic compounds (2.0 ≥ H/C ≥ 1.5) having the highest bioavailability were the most abundant type of DOM in IL, making IL significantly more biodegradable than LL. Under microbial actions, etc., DOM composed of phenolic compounds (aromaticity index (AI) ≤ 0.50 and H/C < 1.5), polyphenols (0.66 ≥ AI > 0.50) and polycyclic aromatics (AI > 0.66) in MBR-treated effluents were enriched and more diverse than in the untreated leachates. Nanofiltration (NF) dramatically lowered the relative abundances of phenolic compounds, polyphenols and polycyclic aromatics in effluent generated by treatment of IL in a MBR. Although the concentration of DOM in NF effluent was comparatively low, the DOM compositions in the resulting NF concentrate were nearly identical to those in MBR effluent, but were more complex than those in an international standard DOM due to a higher content of CHOS and CHONS heteroatomic compounds. Particularly, coagulation in conjunction with ozone/hydrogen peroxide oxidation process were dramatically reduced most polyphenols and polycyclic aromatics from the NF concentrate.

119. 题目: [ASAP] Novel Humo-Pectic Hydrogels for Controlled Release of Agroproducts
文章编号: N20062804
期刊: ACS Sustainable Chemistry & Engineering
作者: Assunta Nuzzo, Pierluigi Mazzei, Marios Drosos, Alessandro Piccolo
更新时间: 2020-06-28
摘要: Sustainable and precision agriculture requires that agroproducts be employed for plants' benefits with maximum efficiency and reduced environmental hazard. Since hydrogels may become efficient vehicles for agroproduct spreading, we prepared novel humo-pectic hydrogels by first blending low methyl-esterified pectin with either humic substances (HS) extracted from different composted biomasses or humic-like substances (HULIS) from depolymerized lignocellulose waste derived by biorefinery activities and, then, by cross-linking with calcium chloride through ionotropic gelation. Hydrogels were characterized by solid-state 13C NMR spectroscopy, scanning electron microscopy (SEM), magnetic resonance imaging (MRI) and rheological analyses. Their ability to work as controlled-release systems was tested by kinetically monitoring the release of a previously incorporated phloroglucinol. Our results indicated that the hydrogels made with HULIS (HP-HULIS) showed a better controlled-release property than those containing HS (HP-HS). This highly depended on the larger content of oligosaccharides, lesser porosity, and greater cross-linking density of HP-HULIS as compared to HP-HS. Our study suggests that the development of a technology based on such novel humo-pectic hydrogels as carriers of bioactive compounds may represent a promising strategy for the controlled and environmentally safe delivery of agroproducts to crops. The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acssuschemeng.0c01986. Photo of HP-HULIS sample, 13C CPMAS NMR spectra of hydrogel components, and T2 relaxation time values of hydrogels (PDF) This article has not yet been cited by other publications.

120. 题目: Effects of rehabilitation through afforestation on soil aggregate stability and aggregate-associated carbon after forest fires in subtropical China
文章编号: N20062803
期刊: Geoderma
作者: Yunxing Bai, Yunchao Zhou, Hongzao He
更新时间: 2020-06-28
摘要:

The recovery of carbon stocks through the afforestation of degraded lands is a management practice that can be applied to mitigate rising concentrations of atmospheric carbon dioxide; however, due to economic pressure, most plantations are cut down in the growth stage, and the effect of forest stand age on soil carbon accumulation is unknown. We evaluated the effects of forest stand age on soil organic carbon (SOC), soil aggregate stability, and aggregate-associated SOC during afforestation. We collected soils along a chronosequence of 10, 20, 40, 60, and 100 years following restoration with P. massoniana after forest fires in the subtropical region of China. The results showed that the soil aggregates were primarily macroaggregates (>10 mm, 2–5 mm), and the stability of the soil aggregates first increased and then decreased as time progressed. The stability of the soil aggregates was at its maximum at 20 years post-planting. The mean weight diameter (MWD), geometric mean diameter (GMD) and fractal dimension (D) were 5.90 ± 0.17 mm, 4.25 ± 0.21 mm and 2.10 ± 0.04 mm, respectively, for the soil aggregates in the 0–20 cm layer. SOC content continuously increased with time since restoration, and SOC storage was mainly concentrated in the soil aggregates with sizes of >10 mm and 2–5 mm. Compared with the forests with restoration times of 10 years, the SOC storage in the 0–20 cm layer in the 20-, 40-, 60-, and 100-year-old forests increased by 10.10%, 9.57%, 31.39% and 69.40%, respectively. Compared with the forests with restoration times of 10 years, the SOC storage in the 80–100 cm layer of 20- and 40-year-old forests did not differ significantly, but those in the 60- and 100-year-old forests increased by 83.76% and 116.85%, respectively. For the forests between 10 and 100 years of age, the soil carbon sequestration rates were 0.33 ± 0.02 (0–20 cm), 0.42 ± 0.07 (20–40 cm), 0.39 ± 0.09 (40–60 cm), 0.33 ± 0.05 (60–80 cm) and 0.28 ± 0.03 (80–100 cm) Mg·C·ha−1·a−1. We concluded that SOC accumulation during afforestation occurs mainly in macroaggregates, which have faster turnover than microaggregates. The soils of mature and over-mature forests still have high carbon storage and sequestration rate, especially in the deeper soil layers (60–80 cm, 80–100 cm).

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