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25761. 题目: Accelerating waste sludge hydrolysis with alkyl polyglucose pretreatment coupled with biological process of thermophilic bacteria: Hydrolytic enzyme activity and organic matters transformation
文章编号: N19062402
期刊: Journal of Environmental Management
作者: Pengtao Gao, Liang Guo, Jian Sun, Yi Wang, Zonglian She, Mengchun Gao, Yangguo Zhao
更新时间: 2019-06-24
摘要: A novel pretreatment method combining thermophilic bacteria (TB) with alkyl polyglucose (APG) was employed to pretreat waste sludge for enhancing the sludge hydrolysis. TB combined with APG pretreatment was effective in the releasing of soluble chemical oxygen demand (SCOD), protein and carbohydrate in extracellular polymeric substances (EPS) when the dosage of APG was below 0.1 g/g TSS. The enhancement of SCOD, carbohydrates and protein in dissolved organic matter (DOM) was promoted by the synthetic effect of APG and TB, which provides more carbon and energy source to the subsequent biochemical processes in sludge digestion. Excitation-emission matrix (EEM) fluorescence spectroscopy revealed that the combined pretreatment was beneficial for the decrease of non-biodegradable materials and the increase of biodegradable materials in DOM, resulting in the enhancement of the biodegradation of waste sludge. The combined use of TB and 0.4 g/g TSS APG achieved the maximal activities of protease (1.8) and α-glucosidase (1.9), and the activities of protease and α-glucosidase were positively correlated to the dosage of APG. The combined pretreatment was advantageous for the sludge reduction and sludge stabilization.
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25762. 题目: Emergent properties of organic matter decomposition by soil enzymes
文章编号: N19062401
期刊: Soil Biology and Biochemistry
作者: Bin Wang, Steven D. Allison
更新时间: 2019-06-24
摘要: Plant residues and soil organic matter are predominantly decomposed by exoenzymes. Many soil carbon models now represent enzymatic decomposition, but the mathematical formulation of this process has been debated over the last 15 years. Some models apply the traditional “forward” Michaelis-Menten equation to represent enzyme kinetics, whereas others apply the “reverse” Michaelis-Menten equation, which assumes that kinetic rates saturate at high enzyme concentrations. Recently the equilibrium chemistry approximation (ECA) has been proposed as an alternative to both Michaelis-Menten formulations. However, because of methodological limitations, in-situ enzyme kinetics—especially in the context of soil system heterogeneity—have been difficult to verify experimentally. Therefore, the overarching goal of our study was to evaluate different enzyme kinetic formulations using model-based evidence at microbial to ecosystem scales. We used a spatially explicit individual- and trait-based microbial model, DEMENT, to circumvent methodological challenges. Although DEMENT assumes forward Michaelis-Menten kinetics at local scales, at the grid scale we found saturating relationships between degradation rate and both substrate concentrations and enzyme concentrations that fit the forward and reverse Michaelis-Menten equations, respectively, at specific successional stages during decomposition. Although forward and reverse Michaelis-Menten equations emerged under some conditions, only the ECA adequately represented decay rates emerging from the spatial-temporal variation in substrate and enzyme concentrations throughout the decomposition process. Our results support a more widespread adoption of the ECA equation in soil biogeochemical modelling at ecosystem scales.

25763. 题目: Alleviation of atrazine toxicity to maize seedlings grown in soils with amendment of biochar derived from wheat under different temperatures
文章编号: N19062305
期刊: Environmental Science and Pollution Research
作者: Yifan Wang, Yi Tang, Qun Jiang, Xinyuan Zhang, Weiling Xie, Ruizhen Li, Wenzhu Liu, Jiaming Kang, Ying Zhang
更新时间: 2019-06-23
摘要: The effects of different biotransformation temperatures (250, 550, and 850 °C) and different dose (0–1%) of biochar on the physiological characteristics of maize seedlings under the stress of atrazine were studied. The results show that atrazine significantly inhibits the growth of maize seedlings, while biochar can alleviate the toxicity of atrazine to seedlings. Compared with the low temperature of biochar, the addition of BC850, the germination rate of maize was significantly increased. The biochars prepared at higher temperatures and adding 1% dose could significantly increase the plant height, while the effect of biochar on root growth of maize seedlings was not significant. According to the data, with the increase of biochar application, the accumulation of atrazine in maize leaves and roots gradually decreased. At the maximum application rate of 1%, the content of atrazine in maize leaves decreased by 58.94%, 60.70%, and 62.75%. The content of atrazine in maize roots decreased by 52.93%, 54.57%, and 55.42%, respectively. Meanwhile, the addition of biochar could slightly increase the chlorophyll content, but the change was not significant statistically, while the content of chlorophyll b increases with the application amount. The content of malondialdehyde (MDA) in roots and leaves decreased first and the increased with the dose of biochar from 0 to 1%. Compared with the atrazine treatment, the content of MDA in leaves and roots decreased significantly, and the lipid peroxidation of maize significantly decreased. With the addition of three kinds of biochar, the soluble content of plant tissues increased gradually, BC550 biochar has the most noticeable remediation effect. Given the toxicity of atrazine in soil, the quality and yield of agricultural products, and the potential health risks to human beings, biochar can be the soil remediation product.

25764. 题目: Increasing organic carbon biolability with depth in yedoma permafrost: ramifications for future climate change
文章编号: N19062304
期刊: Journal of Geophysical Research: Biogeosciences
作者: J.K. Heslop, M. Winkel, K.M. Walter Anthony, R.G.M. Spencer, D.C. Podgorski, P. Zito, A. Kholodov, M. Zhang, S. Liebner
更新时间: 2019-06-23
摘要: Permafrost thaw subjects previously frozen organic carbon (OC) to microbial decomposition, generating the greenhouse gases (GHG) carbon dioxide (CO₂) and methane (CH₄) and fueling a positive climate feedback. Over one‐quarter of permafrost OC is stored in deep, ice‐rich Pleistocene‐aged yedoma permafrost deposits. We used a combination of anaerobic incubations, microbial sequencing, and ultrahigh‐resolution mass spectrometry to show yedoma OC biolability increases with depth along a 12‐m yedoma profile. In incubations at 3 °C and 13 °C, GHG production per unit OC at 12 m depth versus 1.3 m depth was 4.6 and 20.5 times greater, respectively. Bacterial diversity decreased with depth and we detected methanogens at all our sampled depths, suggesting that in situ microbial communities are equipped to metabolize thawed OC into CH₄. We concurrently observed an increase in the relative abundance of reduced, saturated OC compounds, which corresponded to high proportions of C mineralization and positively correlated with anaerobic GHG production potentials and higher proportions of OC being mineralized as CH₄. Taking into account the higher global warming potential (GWP) of CH₄ compared to CO₂, thawed yedoma sediments in our study had 2 times higher GWP at 12 m depth versus 9.0 m depth at 3 °C and 15 times higher GWP at 13 °C. Considering yedoma is vulnerable to processes that thaw deep OC, our findings imply it is important to account for this increasing GHG production and GWP with depth to better understand the disproportionate impact of yedoma on the magnitude of the permafrost carbon feedback.

25765. 题目: Mineralogy dictates the initial mechanism of microbial necromass association
文章编号: N19062303
期刊: Geochimica et Cosmochimica Acta
作者: Courtney A. Creamer, Andrea L. Foster, Corey Lawrence, Jack McFarland, Marjorie Schulz, Mark P. Waldrop
更新时间: 2019-06-23
摘要: Soil organic matter (SOM) improves soil fertility and mitigates disturbance related to climate and land use change. Microbial necromass (the accumulated cellular residues of microorganisms) comprises the majority of soil C, yet the formation and persistence of necromass in relation to mineralogy is poorly understood. We tested whether soil minerals had different microbial necromass association mechanisms. Specifically, we tested whether microbial necromass directly sorbed to mineral surfaces or was consumed by live microorganisms prior to mineral association. Applying Raman microspectroscopy with ¹³C enriched microbial necromass to quantify microbe-mineral interactions, we show that mineralogy alters the initial mechanism of microbial necromass association. In the presence of K-feldspar (lower abiotic C preservation potential), microbial necromass required assimilation by live microorganisms for mineral retention. In contrast, with amorphous aluminum hydroxide (higher abiotic C preservation potential) microbial necromass was retained predominately through abiotic sorption, and was subsequently protected from microbial decomposition. Despite different mechanisms, both minerals retained similar quantities of microbial necromass under biotic conditions. Mineralogy determined not only the quantity of mineral-associated C, but the distinct pathway of microbial necromass association. These findings show the utility of Raman microspectroscopy as a technique to study microbe-mineral interactions, and imply that heterogeneity in mineral-organic interactions could result in gradients of organic matter stability.

25766. 题目: Co-occurrence of geogenic and anthropogenic contaminants in groundwater from Rajasthan, India
文章编号: N19062302
期刊: Science of The Total Environment
作者: Rachel Coyte, Anjali Singh, Kirin Emlet Furst, William Mitch, Avner Vengosh
更新时间: 2019-06-23
摘要: Northwest India suffers from severe water scarcity issues due to a combination of over-exploitation and climate effects. Along with concerns over water availability, endemic water quality issues are critical and affect the usability of available water and potential human health risks. Here we present data from 243 groundwater wells, representing nine aquifer lithologies in 4 climate regions that were collected from the Northwestern Indian state of Rajasthan. Rajasthan is India's largest state by area, and has a significant groundwater reliant population due to a general lack of surface water accessibility. We show that the groundwater, including water that is used for drinking without any treatment, contains multiple inorganic contaminants in levels that exceed both Indian and World Health Organization (WHO) drinking water guidelines. The most egregious of these violations were for fluoride, nitrate, and uranium; 76% of all water samples in this study had contaminants levels that exceed the WHO guidelines for at least one of these species. In addition, we show that much of the groundwater contains high concentrations of dissolved organic carbon (DOC) and halides, both of which are risk factors for the formation of disinfectant byproducts in waters that are treated with chemical disinfectants such as chlorine. By using geochemical and isotopic (oxygen, hydrogen, carbon, strontium, and boron isotopes) data, we show that the water quality issues derive from both geogenic (evapotranspiration, water-rock interactions) and anthropogenic (agriculture, domestic sewage) sources, though in some cases anthropogenic activities, such as infiltration of organic- and nitrate-rich water, may contribute to the persistence and enhanced mobilization of geogenic contaminants. The processes affecting Rajasthan's groundwater quality are common in many other worldwide arid areas, and the lessons learned from evaluation of the mechanisms that affect the groundwater quality are universal and should be applied for other parts of the world.
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25767. 题目: Preparation of biochar via pyrolysis at laboratory and pilot scales to remove antibiotics and immobilize heavy metals in livestock feces
文章编号: N19062301
期刊: Journal of Soils and Sediments
作者: Renqiang Tian, Chunxing Li, Shengyu Xie, Futian You, Zhihong Cao, Zhihong Xu, Guangwei Yu, Yin Wang
更新时间: 2019-06-23
摘要: Purpose: Pyrolysis is the most effective method to completely remove antibiotics and immobilize heavy metals from livestock feces. However, the effect of the pyrolysis temperature on antibiotic removal at laboratory and pilot scales is still unclear. Materials and methods: The pyrolysis technique was used to convert pig manure (PM) and chicken manure (CM) into biochar at different temperatures from 300 to 700 °C in a laboratory-scale test. The performance of antibiotic removal and heavy metal immobilization in livestock feces was studied, and the optimal temperature of 600 °C was selected for the pilot-scale verification. Results and discussion: The results showed that the removal of the antibiotics tylosin (TYL), tetracycline (TC), chlortetracycline (CTC), doxycycline (DOXY), sulfamethazine (SMZ), sulfadiazine (SDZ), and sulfamethoxazole (SMX) was satisfactory, and all seven typical antibiotics were completely removed at 600 °C. In addition, the heavy metals zinc (Zn), copper (Cu), chromium (Cr), lead (Pb), nickel (Ni), cadmium (Cd), and arsenic (As) in the manure were well immobilized, and higher temperatures (above 600 °C) favored their immobilization. The results of heavy metal immobilization and antibiotic removal of the pilot-scale test were similar to those of the laboratory-scale test. Conclusions: Laboratory- and pilot-scale experiments showed that the current study provided a safe method and technology for treating and recycling livestock feces into biochar via the pyrolysis process.

25768. 题目: Toxicity of aluminum to Ceriodaphnia dubia in low-hardness waters as affected by natural dissolved organic matter
文章编号: N19062207
期刊: Environmental Toxicology and Chemistry
作者: John Besser, Danielle Cleveland, Chris Ivey, Laura Blake
更新时间: 2019-06-22
摘要: We conducted a series of 7‐d toxicity tests with Ceriodaphnia dubia in dilutions of low‐hardness natural waters, which contained dissolved organic carbon (DOC) concentrations up to 10 mg/L. Stream waters were mixed with well water to achieve 2 target hardness levels (20 and 35 mg/L) and 4 DOC concentrations. Tests with Al‐spiked waters were conducted in a controlled CO₂ atmosphere to maintain pH in the range, 6.0‐6.5. Results were used to estimate effect concentrations for survival and reproduction, expressed as total (unfiltered) Al concentrations. There were small differences in total‐Al thresholds between waters with 20 and 35 mg/L hardness, but effect concentrations for C. dubia survival (LC50) and reproduction (EC20) increased log‐linearly with increasing DOC concentrations in the range, 0.3 mg/L to 6 mg/L. Slopes of these regressions were similar to slopes from data used to revise the USEPA water quality criterion for Al, but toxic effects occurred in the present study at total‐Al concentrations 8‐ to 10‐fold greater than toxicity values used for criteria development. This difference probably reflects the long equilibration (aging) times of Al test waters used in the present study (up to 192 hr) compared to very short (3 hr) equilibration times in other studies used for criteria development. These results confirm the importance of DOC as a control on Al toxicity in low‐hardness waters, but they also demonstrate that total‐Al concentrations are not predictive of Al toxicity, except under defined water quality (pH, hardness, DOC) and exposure conditions (e.g., aging of test waters).

25769. 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.

25770. 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.

25771. 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.

25772. 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.

25773. 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.

25774. 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 UV_254nm 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.
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25775. 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.

25776. 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.

25777. 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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25778. 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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25779. 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.
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25780. 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).