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12661. 题目: Chemically oxidized biochar increases ammonium- 15 N recovery and phosphorus uptake in a grassland
文章编号: N19062206
期刊: Biology and Fertility of Soils
作者: Shamim Mia, Balwant Singh, Feike A. Dijkstra
更新时间: 2019-06-22
摘要: Soil amendment with biochar is shown to be a low-cost carbon sequestration option while its properties contribute to nutrient dynamics. The properties of biochar can be purposefully modified using different techniques including chemical oxidation. A change in biochar functionality, to an equivalent state of natural aging, could alter plant nutrient use efficiency, particularly nitrogen (N) and phosphorus (P), which however has not been examined yet. Here, we examined 15N recovery and P uptake in mixtures of clover (Trifolium repens) and ryegrass (Lolium perenne) after biochar amendment at different oxidation states (i.e., fresh, 5%OBC and 15%OBC, oxidized with 5 and 15% H2O2, respectively) and addition of 15NH4+-N and 15NO3-N. Overall, after 30 days of growth, the total 15N recovery in plant and soil was 41% greater with NH4+-N than with NO3-N addition. However, the 15N recovery from NH4+-N addition was greater in the oxidized biochar treatments than the control and fresh biochar treatments (a significant biochar × N interaction). Chemical oxidation also increased leaching of NO3-N and phosphate-P while greater plant P uptake occurred in the 15%OBC treatment with NH4+-N addition. An increase in cation exchange sites with oxidized biochar may have increased NH4+-N retention and biomass production (N uptake) and, thus, 15N recovery. The increase in P availability may further have increased plant biomass production in the 15%OBC treatment with NH4+-N. Our results suggest that oxidized biochar could increase primary productivity by increasing NH4+-N use efficiency and P availability while increasing the risk of NO3-N and phosphate-P leaching.

12662. 题目: Effects of struvite-humic acid loaded biochar/bentonite composite amendment on Zn(II) and antibiotic resistance genes in manure-soil
文章编号: N19062205
期刊: Chemical Engineering Journal
作者: Yuan Li, Xuejiang Wang, Jing Li, Yuan Wang, Jingke Song, Siqing Xia, Huanping Jing, Jianfu Zhao
更新时间: 2019-06-22
摘要: In this study, struvite-humic acid loaded biochar/bentonite composite (HMCC), a recovery product of humic acid, nitrogen and phosphorus from biogas slurry, was prepared and used for simultaneous control of Zn(II) and antibiotic resistance genes (ARGs) pollution in manure-soil. The adsorption performance and mechanism of Zn(II) on HMCC were first studied in aqueous solution. The adsorption data fitted well to the Freundlich isotherm model, and the primary mechanisms of Zn(II) absorbed by HMCC involved the formation of Zn3(PO4)2·4H2O and humic acid-metal complex. The changes of Zn(II) content, antibiotic resistance genes (ARGs) and bacterial communities during the remediation of Zn(II) contaminated manure-soil were analyzed simultaneously. With HMCC amendment, the content of bio-available Zn(II) (bio-Zn) efficiently reduced from 847.4 mg/g to 739.2 mg/g and the total relative abundance of ARGs accordingly decreased by 37.18%. RDA analysis indicated that soil pH and bio-Zn were the main contributors to the fluctuations of soil ARGs. Spearman correlation analysis revealed that the potential hosts for ARGs mainly belonged to the phylum Actinobacteria. In addition, HMCC addition increased the diversity of bacterial community but significantly reduced the abundance of an antibiotic resistant bacteria-Actinobacteria. It is the first study to demonstrate the feasibility of HMCC as an environmentally friendly amendment to immobilize Zn(II) and mitigate the dissemination of ARGs in manure-soil.

12663. 题目: Mechanism of enhancing pyrene-degradation ability of bacteria by layer-by-layer assembly bio-microcapsules materials
文章编号: N19062204
期刊: Ecotoxicology and Environmental Safety
作者: Fucai Deng, Jianteng Sun, Rongni Dou, Wangming Deng, Yi Liu, Chen Yang, Zhi Dang
更新时间: 2019-06-22
摘要: The mechanism of improving pyrene (PYR)-degrading ability of bacteria CP13 in Layer-by-layer (LBL) assembly chitosan/alginate (CHI/ALG) bio-microcapsules was investigated. Flow cytometry analysis showed that LBL microcapsules could effectively slow down the increasing rate of bacterial cell membrane permeability and the decreasing rate of the membrane potential, so as to reduce the death rate and number of the cells, which could protect the degrading bacteria. The results of Fluorescence spectrum, circular dichroism (CD) spectrum and laser light scattering (LLS) analysis revealed that the other possible mechanism for LBL microcapsules to promote bacterial degradation were following: CHI could enter the secondary structure of the protein of the extracellular polymeric substances (EPS) from CP13 and combined with EPS to generate a stable ground material, which had larger molecular weight (3.76×106 g mol-1) than the original EPS (2.52×106 g mol-1). The combination of CHI and EPS resulted in the decrease of the density of EPS from 1.18 to 0.72 g L-1, suggesting that CHI can loosen the EPS configurations, improving the capture ability of bacteria for PYR as well as the mass transfer of PYR from the extracellular to intracellular, thus eventually promoting the bacteria degrade performance.

12664. 题目: Emerging investigator series: Spatial distribution of dissolved organic matter in ice and at air-ice interfaces
文章编号: N19062203
期刊: Environmental Science: Processes Impacts
作者: Subha Chakraborty, Tara Kahan
更新时间: 2019-06-22
摘要: Dissolved organic matter (DOM) is a common solute in snow and ice at Earth’s surface. Its effects on reaction kinetics in ice and at air-ice interfaces can be large, but are currently difficult to quantify. We used Raman microscopy to characterize the surface and bulk of frozen aqueous solutions containing humic acid, sodium dodecyl sulfate (SDS), and citric acid at a range of concentrations and temperatures. The surface-active species (humic acid and SDS) were distributed differently than citric acid. Humic acid and SDS are almost completely excluded to the air-ice interface during freezing, where they form a film that coats the surface nearly completely. A liquid layer that coats the entire surface was observed at all humic acid and SDS concentrations. Citric acid, which is smaller and less surface active, is excluded to liquid channels at the air-ice interface and within the ice bulk, as has previously been reported for ionic solutes. Incomplete surface wetting was observed at all citric acid concentrations and at all temperatures (up to 5 oC). Citric acid appears to be solvated in frozen samples, but SDS and humic acid do not. These results will improve our understanding of the effects of organic solutes on environmental and atmospheric chemistry within ice and at air-ice interfaces.

12665. 题目: Amino modification of rice straw-derived biochar for enhancing its cadmium (Ⅱ) ions adsorption from water
文章编号: N19062202
期刊: Journal of Hazardous Materials
作者: Yaping Zhang, Xiupeng Yue, Xu Weiwei, Huiyan Zhang, Fei Li
更新时间: 2019-06-22
摘要: To enhance the adsorption capacity of Cd2+, -NH2 groups were introduced into the rice straw-derived biochar surface by combining nitrification and amination. The batch and continuous Cd2+ adsorption experiments were performed to determine the role of -NH2 groups on the surface of biochar. The physical and chemical characteristics were analyzed for comparison. The results indicated that the adsorption capacity of the modified biochar (BC-NH2) was boosted by 72.1%. The results of continuous adsorption experiments in fixed bed columns showed that the penetration time of BC-NH2 was three times that of original biochar. The adsorption of Cd2+ by BC-NH2 is a spontaneous endothermic chemical reaction, which was obtained by combing sorption kinetics, isotherms and thermodynamic analysis. The Cd2+ adsorption was mainly the complexation between –NH2 group on biochar surface and Cd2+ in solution. Finally, a possible interaction mechanism between Cd2+ and BC-NH2 was proposed.

12666. 题目: Removal of landfill leachate ultraviolet quenching substances by electricity induced humic acid precipitation and electrooxidation in a membrane electrochemical reactor
文章编号: N19062201
期刊: Science of The Total Environment
作者: Xingjian Liu, John T. Novak, Zhen He
更新时间: 2019-06-22
摘要: Persistent UV quenching substances (UVQS) in landfill leachate can affect the effectiveness of UV disinfection in domestic wastewater treatment systems when leachate is being co-treated. As a result, effective onsite leachate pre-treatment will have to be implemented to reduce the UV quenching capability. Herein, a membrane electrochemical reactor (MER) was developed and investigated for treating UV quenching organics contained in landfill leachate. Compared to a control reactor that did not have a membrane separator, the MER achieved significantly higher removals of both dissolved organic carbon (61.5 ± 4.1%) and UV254nm absorbance (63.4 ± 8.4%). This enhanced performance was likely due to the combined effects of humic acid precipitation and augmented oxidation of organics. The MER was able to remove 89.1 ± 2.9% of total nitrogen from the leachate while recovering about 51% of the influent ammonia in the catholyte, in comparison to 38.1 ± 4.4% of total nitrogen removal by the control reactor. The MER consumed significantly less electrical energy with specific energy consumption of 70.62 kWh kg−1 DOC or 33.03 kWh kg−1 sCOD, compared to that of the control reactor (211.8 kWh kg−1 DOC or 55.02 kWh kg−1 sCOD). A current density of 20 mA cm−2 was considered optimal in terms of both UVQS removal and energy efficiency. Consideration should be given to the spacing of electrodes to minimize internal resistance and also to avoid trapping of the produced gas bubbles. These results collectively suggest that the MER is a promising onsite pretreatment approach for landfill leachate and further exploration of this technology should be encouraged.
图文摘要:

12667. 题目: Effects of the Chemical Structure, Surface, and Micropore Properties of Activated and Oxidized Black Carbon on the Sorption and Desorption of Phenanthrene
文章编号: N19062112
期刊: Environmental Science & Technology
作者: Shujie Hu, Dainan Zhang, Yu Yang, Yong Ran, Jingdong Mao, Wenying Chu, Xiaoyan Cao
更新时间: 2019-06-21
摘要: The effects of the chemical structure, surface properties, and micropore of modified black carbon samples (BCs) on the sorption mechanism of hydrophobic organic contaminants (HOCs) are discussed. Activated and oxidized BCs were produced from a shale kerogen at 250–500 °C by chemical activation regents (KOH and ZnCl2) and then by oxidative regents (H2O2 and NaClO). The surface properties (water contact angel, Boehm titration, and cation exchange capacity, CEC), structural properties (advanced solid-state 13C NMR), micropore properties (CO2 adsorption), mesopore properties (N2 adsorption), and sorption and desorption properties of phenanthrene were obtained. The results showed that ZnCl2-activated BCs had higher basic surface groups, CEC values, aromatic carbon contents, micropore volumes, and adsorption volumes but exhibited lower acidic surface groups than the KOH-activated BCs did. Micropore modeling and sorption irreversibility indicated that the micropore filling was the main sorption mechanism of phenanthrene. In addition, ZnCl2 activated and NaClO oxidized BCs showed a nice regression equation between adsorption volumes and micropore volumes (CO2–V0) as follows: Q0′ = 0.495V0 + 6.28(R2 = 0.98, p < 0.001). Moreover, the contents of nonprotonated aromatic carbon, micropore volumes, and micropore sizes are the critical factors to micropore filling mechanism of phenanthrene on BCs. The size of fused aromatic rings was estimated from the recoupled 1H–13C dipolar dephasing, and the BC structural models at temperatures ranging from 300 to 500 were proposed. This finding improves our understanding of the sorption mechanism of HOCs from the perspectives of chemical structure and micropore properties.

12668. 题目: Structural characteristics of humic-like acid from microbial utilization of lignin involving different mineral types
文章编号: N19062111
期刊: Environmental Science and Pollution Research
作者: Shuai Wang, Junping Xu, Xi Zhang, Yu Wang, Jiayan Fan, Lan Liu, Nan Wang, Dianyuan Chen
更新时间: 2019-06-21
摘要: This paper determines the impact of two clay minerals (kaolinite and montmorillonite) and three oxides (goethite, δ-MnO2, and bayerite) on the elemental composition and FTIR spectra of humic-like acid (HLA) extracted from microbial-mineral residue formed from the microbial utilization of lignin in liquid shake flask cultivation. Goethite, bayerite, and δ-MnO2 showed higher enrichment capabilities of C and O + S in the HLA than kaolinite and montmorillonite. Goethite showed the highest retention of organic C, followed by bayerite, but kaolinite exhibited the least exchangeability. Kaolinite and montmorillonite enhanced microbial consumption of N, resulting in the absence of N in HLA. A few aliphatic fractions were preferentially gathered on the surfaces of kaolinite and montmorillonite, making the H/C ratios of HLA from the clay mineral treatments higher than those of HLA from the oxide treatments. δ-MnO2 was considered the most effective catalyst for abiotic humification, and goethite and bayerite ranked second and third in this regard. This trend was proportional to their specific surface areas (SSAs). However, comparing the effects of different treatments on the promotion of HLA condensation by relying solely on the SSA of minerals was not sufficient, and other influencing mechanisms had to be considered as well. Additionally, Si–O–Al and Si–O of kaolinite participated in HLA formation, and Si–OH, Si–O, and Si–O–Al of montmorillonite also contributed to this biological process. Fe–O and phenolic –OH of goethite, Mn–O of δ-MnO2, and Al–O of bayerite were all involved in HLA formation through ligand exchange and cation bridges. Lignin was better protected from microbial decomposition by the kaolinite, bayerite, and δ-MnO2 treatments, which caused lignin-like humus (HS) formation. Under the treatments of δ-MnO2, goethite, and bayerite, HLA showed a greater degree of condensation compared to HLA precipitated by kaolinite and montmorillonite. Contributions from Si–O, and Si–O–Al of clay minerals, and Fe–O, Mn–O, and Al–O of oxides were the mechanisms by which minerals catalyzed the formation of HS from lignin.

12669. 题目: Enhanced nitrogen removal in an aerobic granular sequencing batch reactor under low DO concentration: Role of extracellular polymeric substances and microbial community structure
文章编号: N19062110
期刊: Bioresource Technology
作者: Lilong Yan, Mingyue Zhang, Yue Liu, Cong Liu, Yudan Zhang, Shuang Liu, Liangbin Yu, Guoxin Hao, Zhonglin Chen, Ying Zhang
更新时间: 2019-06-21
摘要: In this study, the role of extracellular polymeric substances (EPSs) in nitrogen removal and the microbial community structure of aerobic granular sludge (AGS) were analyzed under different dissolved oxygen (DO) conditions (6–7, 4–5, and 2–3 mg·L−1). The EPSs transported and retained nitrogen in the denitrification process, and the total inorganic nitrogen (TIN) in the EPSs decreased from 6.09 to 5.54 mg·g−1 MLSS when the DO concentration decreased from 6–7 to 2–3 mg·L−1. The microbial community showed different core denitrifying bacterial populations involved in nitrogen removal in the AGS system under different DO conditions, with more species when they were higher relative abundances of denitrifying bacteria participating in the nitrogen removal process in AGS under low DO conditions, including Hydrogenophilaceae, Thauera, Enterobacter, Xanthomonadaceae_unclassified, Comalmonadaceae_unclassified, Nitrosomonas and Paracoccus. This study provides a more comprehensive understanding of the DO effect on the TIN removal mechanism by AGS.
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12670. 题目: Variable responses of nitrification and denitrification in a paddy soil to long-term biochar amendment and short-term biochar addition
文章编号: N19062109
期刊: Chemosphere
作者: Lili He, Jun Shan, Xu Zhao, Shenqiang Wang, Xiaoyuan Yan
更新时间: 2019-06-21
摘要: Biochar-mediated change in soil N transformations has gained much attention. Biochar properties undergo changes through ageing process that may impact variably on N cycling, yet the degree to which soil N transformations may be impacted by biochar ageing process on long-time scale remains unclear. Here, we compared the effects on nitrification, denitrification and N2/N2O gas flux of short-term fresh biochar addition with long-term biochar amendment over six consecutive years in a paddy soil under identical amounts of soil organic C contents. We found that short-term treatments elicited a stronger effect on nitrification than long-term treatments, due to more positive effects on soil pH and ammonia monooxygenase gene (amoA) abundance of ammonia oxidizing bacterial (AOB). However, there were contrasting effects on soil denitrification and total N gas loss for two types of biochar addition, where the long-term treatments limited availability of C and N, and decreased net NO3 reduction and total N gas (N2O + N2) losses by up to 55.5% and 25%. Short-term biochar addition increased dissolved organic C, nutrient content and soil pH, enhanced net NO3 reduction by 88.7%, also reduced the ratio of nitrite reductase genes (nirS and nirK) and nitrous oxide reductase gene (nosZ) and N2O emissions, but increased total N gas loss by 0.2–1.2 times. Our study quantified the differences in nitrification and denitrification capacity in response to short-term biochar addition and long-term biochar amendment and bridged the knowledge-gaps of fresh and aged biochar-mediated N transformation.
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12671. 题目: Differential absorbance study of interactions between europium, soil and aquatic NOM and model compounds
文章编号: N19062108
期刊: Chemosphere
作者: Yao Chen, Massimiliano Fabbricino, Vincenzo Luongo, Gregory V. Korshin
更新时间: 2019-06-21
摘要: This study compared the binding of europium by soil and aquatic natural organic matter (NOM) exemplified by Pahokee Peat humic acid (PPHA) and Northern Reservoir NOM, respectively. NOM/Eu3+ interactions were measured based on the differential absorbance approach. The experimental results show that the binding of Eu3+ by humic acid isolated from agricultural soil results in several features of the differential spectra that are distinct from those observed for aquatic NOM. These features may be associated with the presence in soil NOM of functional groups similar to gallic acid. The binding of Eu3+ by NOM was modeled using a phenomenological approach that accounted for the involvement of dissimilar metal-binding functionalities. This study also introduced the concept of integrated differential absorbance; the use of that parameter allowed achieving a close fit between the experimental and model data. This study presents an alternative approach to ascertain mechanisms of, and differences in the interactions of europium with model compounds and natural organic matter with the provenance from soil and surface water.
图文摘要:

12672. 题目: Assessing equilibria of organo-arsenic complexes and predicting uptake of arsenic by wheat grain from organic matter amended soils
文章编号: N19062107
期刊: Chemosphere
作者: Jajati Mandal, Debasis Golui, Siba Prasad Datta
更新时间: 2019-06-21
摘要: In view of limited information, a laboratory experiment was conducted to study the stability of organo-arsenic complexes as affected by competing anions i.e. phosphate, nitrate and sulphate. For this purpose, humic acid (HA) and fulvic acid (FA) were extracted from farmyard manure (FYM), vermicompost (VC), sugarcane bagasse (SB) and soil. A pot experiment was also conducted with 4 levels each of arsenic (As) (10, 20, 30 and 40 mg kg−1) and amendments (no amendment, FYM, VC and SB at the rate of 10 t ha−1 each). Results indicate that stability of FA extracted from sugarcane bagasse have the highest stability constant (log K) as 9.77 and the corresponding mole ratio (x) value of 1.51. The phosphate was the most effective in replacing As from organo-As complexes followed by sulphate and nitrate. Under pot culture study, As content in wheat grain was the lowest in sugarcane bagasse amended soil followed by FYM and VC at all levels of As application. Solubility-free ion activity model was most effective in predicting As uptake by wheat grain based on Olsen extractable As, pH and Walkley & Black organic C. Efficacy of organic amendments in reducing health hazard for intake of As through consumption of wheat grain grown on contaminated soil was also reflected in the values of hazard quotient (HQ).

12673. 题目: Preferential binding properties of carboxyl and hydroxyl groups with aluminium salts for humic acid removal
文章编号: N19062106
期刊: Chemosphere
作者: Jina Song, Xin Jin, Xiaochang C. Wang, Pengkang Jin
更新时间: 2019-06-21
摘要: To systematically elucidate the removal characteristics of humic acid (HA), which are highly dependent on the molecular structure of HA, a series of representative HA model compounds containing different numbers and positions of carboxyl and hydroxyl groups were selected, and the chemical reaction behaviour between HA and aluminium coagulants was investigated. The results indicated that the number of carboxyl groups in the benzene ring and binding environment had great effects on the Al-binding properties of HA molecules. Under weakly acidic conditions, coordination occurred between carboxyl and Al ions, and the complexing capacity was restricted by the substituted position of hydroxyl groups. Under neutral conditions or at higher coagulant dosages, sweep coagulation occurred by surface complexation of aluminium hydroxide by carboxyl groups and hydrogen bonding between the hydroxyl group and aluminium hydroxide; this process was dependent on the substitutive pattern of the functional groups. Moreover, increased aliphatic chain length and benzene ring size could enhance hydrophobicity, and hence resulted in higher coagulation efficiency. This study provided new insight into the mechanism of the interaction between HA and aluminium coagulants.
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12674. 题目: Improving ultrafiltration membrane performance with pre-deposited carbon nanotubes/nanofibers layers for drinking water treatment
文章编号: N19062105
期刊: Chemosphere
作者: Xiaoxiang Cheng, Weiwei Zhou, Peijie Li, Zixiao Ren, Daoji Wu, Congwei Luo, Xiaobin Tang, Jinlong Wang, Heng Liang
更新时间: 2019-06-21
摘要: To efficiently improve the performance of ultrafiltration (UF) membrane for drinking water treatment, carbon nanotubes (CNTs) and carbon nanofibers (CNFs) were utilized as pre-deposited coating layers on membrane surface. A comparative study between these two carbon nanomaterials for enhancing pollutants removal and mitigating membrane fouling induced by natural organic matter (NOM) was carried out. The surface morphologies were characterized by scanning electron microscopy, and the results indicated that the CNTs coating layer was more dense and homogeneous with a smaller pore size than that of CNFs. The removal and antifouling performance of CNTs/CNFs coated membranes were investigated with typical NOM, i.e., humic acid, bovine serum albumin, sodium alginate, as well as natural surface water. The results showed that the presence of coating layers was very effective to improve the rejection rate of NOM, among which CNTs exhibited significant better performance than CNFs. The fouling control performance was influenced by the NOM fraction and coating mass (6–50 g/m2). Generally, CNTs coating layer was more efficient in alleviating both reversible and irreversible membrane fouling, while CNFs exhibited limited effect on irreversible fouling control. Both pre-adsorption and size exclusion contributed to the rejection of membrane foulants, thus reducing the organics directly contacted with the underlying membrane. In natural surface water treatment, the pre-deposited coating layers significantly delayed the transition of fouling mechanisms from pore blocking to cake filtration. The experimental results were expected to illustrate the feasibility of pre-deposited CNTs/CNFs layers for enhancing membrane performance during drinking water treatment.
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12675. 题目: Impact of biochar amendment on the abundance and structure of diazotrophic community in an alkaline soil
文章编号: N19062104
期刊: Science of The Total Environment
作者: Xiaoyu Liu, Cheng Liu, Wenhui Gao, Chen Xue, Zonghao Guo, Li Jiang, Feng Li, Yuan Liu
更新时间: 2019-06-21
摘要: Biological nitrogen (N) fixation contributes to the pool of plant-available N in soil and helps to minimize the use of inorganic N fertilizer in agricultural ecosystems. Although diazotrophs play an important role in the biological fixation of atmospheric N2 in a range of soil types, the knowledge of their response to biochar amendment is still limited. Here, using the nifH gene as a molecular marker, we investigated the short-term effect of biochar application on the abundance, community composition and activity of diazotroph in an alkaline soil. A field trial was established before soybean sowing in 2017 and five treatments were included: inorganic NPK fertilizer (CK); inorganic NPK fertilizer + wheat straw (CS); inorganic NPK fertilizer + low rate of biochar (B4); inorganic NPK fertilizer + high rate of biochar (B20); biochar compound fertilizer (BCF). The field trial was lasted for one crop season and samples were collected by soybean harvest. The results showed that biochar addition generally increased the concentration of soil organic carbon (SOC) and available phosphorous (AP), while B20 treatment significantly increased the total nitrogen (TN) and available potassium (AK). Biochar addition treatments increased the nifH gene abundance and altered the community structure of soil diazotrophs. The abundance of nifH gene was positively correlated with SOC, indicating that increasing SOC potentially affected diazotrophic population in the alkaline soil. Community structure of diazotrophs in the CS treatment was similar with the CK treatment; thus, there was no effect of crop straw on diazotroph community structure. In contrast, the application of biochar and biochar compound fertilizer altered the diazotroph community structure with shifts in the dominant genus, with higher Sinorhizobium in the biochar-amended treatments. SOC, C/N and AP were the key factors correlated with change in diazotroph community structure. Overall, our results suggest that the addition of biochar or biochar compound fertilizer could increase the abundance and alter the community structure of diazotrophs, which may benefit N fixation in alkaline agricultural soil. Conversely, the direct straw return had no effect on the abundance and community structure of diazotrophs.
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12676. 题目: Strengthened dewaterability of coke-oven plant oily sludge by altering extracellular organics using Fe(II)-activated persulfate oxidation
文章编号: N19062103
期刊: Science of The Total Environment
作者: Guangyin Zhen, Yujie Tan, Taipu Wu, Jianhui Wang, Xueqin Lu, Youcai Zhao, Xuefeng Zhu, Jing Niu, Jianying Xiong
更新时间: 2019-06-21
摘要: Although oily sludge has tremendous resource recovery value, its high water content has hindered its treatment and reuse. This study systematically explored the technical feasibility of using Fe(II)-activated persulfate oxidation (Fe2+/S2O82−) to enhance the dewaterability of oily sludge. To identify the main factors controlling sludge dewatering, this study measured changes in chemical oxygen demand, ammonia nitrogen (NH4+-N) and extracellular polymeric substances (EPS). Results showed that at 0.1 mmol-Fe2+/g-VSS and 0.08 mmol-S2O82−/g-VSS, capillary suction time (s) was reduced by roughly 36.1% within 1 min and dewaterability was strengthened strongly. Sulfate radicals originating from Fe2+/S2O82− oxidized a large amount of EPS, leading to liberation of EPS-bound water. A similar declining trend in NH4+-N was evident as a result of the strong oxidizing ability of sulfate radicals. Further analysis via scanning electron microscopy and thermogravimetric-Fourier transform infrared spectrometry revealed that Fe2+/S2O82− oxidation destroyed the water-oil-gel-like structure of the oily sludge, thereby accelerating the separation of solids and water while reducing CO2 emissions during the subsequent pyrolysis. Therefore, oily sludge dewatering was enhanced significantly by the Fe2+/S2O82− process.
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12677. 题目: Triple oxygen isotopic evidence for atmospheric nitrate and its application in source identification for river systems in the Qinghai-Tibetan Plateau
文章编号: N19062102
期刊: Science of The Total Environment
作者: Xinghui Xia, Siling Li, Fan Wang, Sibo Zhang, Yunting Fang, Jianghanyang Li, Greg Michalski, Liwei Zhang
更新时间: 2019-06-21
摘要: Nitrate source identification in river systems is important for water quality management. Recently, the oxygen isotopic anomaly of nitrate in atmospheric deposition (Δ17Oatm) is used to identify unprocessed atmospheric nitrate in river systems to reduce the uncertainty caused by the wide range of δ18O. In high-elevation regions, such as the Qinghai-Tibetan Plateau (QTP) featured with lower temperature and pressure as well as strong radiation, the Δ17Oatm might be different from that in low-elevation regions, but no relevant studies have been reported. In this work, Δ17Oatm in the QTP was studied, and the fingerprints of nitrate isotopes in synthetic fertilizer, livestock manure, domestic sewage, and soil organic nitrogen (SON) were identified and used to quantify various source contributions to riverine nitrate in the Yellow River and Changjiang River source regions located in the QTP during 2016–2017. The results showed that the average of Δ17Oatm in the QTP was 16.4‰, lower than the range (19–30‰) reported for the low-elevation regions. The possible mechanism is decreased O3 as well as increased hydroxyl and peroxy radical levels in the troposphere caused by the climate condition and ozone valley in the QTP will affect the production pathways of atmospheric nitrate. By combining the sewage discharge data with the output results of the SIAR (stable isotope analysis in R) model based on the stable isotope data, manure was determined to be one of the major sources to riverine nitrate for both rivers. The contributions of various sources to riverine nitrate were 47 ± 10% for manure, 30 ± 5% for SON, 10 ± 4% for atmospheric precipitation, 9 ± 2% for synthetic fertilizer, and 4 ± 0% for sewage in the Yellow River source region. This study indicates that the unique atmospheric conditions in the QTP have led to a lower Δ17Oatm value, and atmospheric source makes a considerable contribution to riverine nitrate in the QTP.
图文摘要:

12678. 题目: Reduced tillage and increased residue retention increase enzyme activity and carbon and nitrogen concentrations in soil particle size fractions in a long-term field experiment on Loess Plateau in China
文章编号: N19062101
期刊: Soil and Tillage Research
作者: Haiqing Chen, Qiong Liang, Yuanshi Gong, Yakov Kuzyakov, Mingsheng Fan, Alain F. Plante
更新时间: 2019-06-21
摘要: Soil organic matter (SOM) concentration and enzyme activity are important biochemical indicators of soil health for assessing the sustainability of agricultural management practices. However, little is known about the long-term effects of tillage and crop residue management on SOM and enzyme activities in soil particle-size fractions on the Loess Plateau of Northern China. The objective of this study was to investigate the effects of 11 years of combined tillage and crop residue management treatments on soil organic carbon (SOC), total nitrogen (TN) concentrations and enzyme activities in bulk soil and particle-size fractions from a rainfed wheat (Triticum aestivum L.) monoculture system in this region. We hypothesized that reduced tillage and increased residue retention would increase SOC, TN and enzyme activities in both bulk soil and particle-size fractions, and that enzyme activity would serve as a more sensitive indicator of soil health in response to management. Compared with conventional tillage and residue removal (CTRR), reduced tillage and stubble mulch residue retention (RTSM) increased bulk soil activities of most enzymes (sulfatase +68%, invertase +62%, β-glucosidase +58%, dehydrogenase +46%). These increases were greater than the relative increases in total SOC (34%) and TN (33%) concentrations, supporting our hypothesis of a stronger response in microbial activity to management than total element stocks. The RTSM treatment also increased SOC and TN concentrations, as well as β-glucosidase, acid phosphatase and urease activities in all particle-size fractions (2000-250, 250-53, 53-2 and < 2 μm) compared with the CTRR treatment. Both β-glucosidase and acid phosphatase showed a general decrease from coarse- to fine-sized fractions, and resembled the distribution of SOC and TN concentrations in particle-size fractions. Conversely, urease activity was greater in sand and clay fractions, which was decoupled from SOC and TN distributions. Our results indicate that biological indicators of soil health were more sensitive than C and N stocks to cumulative long-term changes in tillage and residue management.

12679. 题目: Archaea dominate oxic subseafloor communities over multimillion-year time scales
文章编号: N19062016
期刊: Science Advances
作者: Aurèle Vuillemin, Scott D. Wankel, Ömer K. Coskun, Tobias Magritsch, Sergio Vargas, Emily R. Estes, Arthur J. Spivack, David C. Smith, Robert Pockalny, Richard W. Murray, Steven D’Hondt, William D. Orsi
更新时间: 2019-06-20
摘要: Ammonia-oxidizing archaea (AOA) dominate microbial communities throughout oxic subseafloor sediment deposited over millions of years in the North Atlantic Ocean. Rates of nitrification correlated with the abundance of these dominant AOA populations, whose metabolism is characterized by ammonia oxidation, mixotrophic utilization of organic nitrogen, deamination, and the energetically efficient chemolithoautotrophic hydroxypropionate/hydroxybutyrate carbon fixation cycle. These AOA thus have the potential to couple mixotrophic and chemolithoautotrophic metabolism via mixotrophic deamination of organic nitrogen, followed by oxidation of the regenerated ammonia for additional energy to fuel carbon fixation. This metabolic feature likely reduces energy loss and improves AOA fitness under energy-starved, oxic conditions, thereby allowing them to outcompete other taxa for millions of years.

12680. 题目: A tectonically driven Ediacaran oxygenation event
文章编号: N19062015
期刊: Nature Communications
作者: Joshua J. Williams, Benjamin J. W. Mills, Timothy M. Lenton
更新时间: 2019-06-20
摘要: The diversification of complex animal life during the Cambrian Period (541–485.4 Ma) is thought to have been contingent on an oxygenation event sometime during ~850 to 541 Ma in the Neoproterozoic Era. Whilst abundant geochemical evidence indicates repeated intervals of ocean oxygenation during this time, the timing and magnitude of any changes in atmospheric pO2 remain uncertain. Recent work indicates a large increase in the tectonic CO2 degassing rate between the Neoproterozoic and Paleozoic Eras. We use a biogeochemical model to show that this increase in the total carbon and sulphur throughput of the Earth system increased the rate of organic carbon and pyrite sulphur burial and hence atmospheric pO2. Modelled atmospheric pO2 increases by ~50% during the Ediacaran Period (635–541 Ma), reaching ~0.25 of the present atmospheric level (PAL), broadly consistent with the estimated pO2 > 0.1–0.25 PAL requirement of large, mobile and predatory animals during the Cambrian explosion.

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