17301. 题目: Investigation of the sorption of 17α-ethynylestradiol (EE2) on soils formed under aerobic and anaerobic conditions
作者: Lili Szabó, Anna Vancsik, Csilla Király, Marianna Ringer, Attila Kondor, Gergely Jakab, Zoltán Szalai, Tibor Filep
摘要: A study was conducted on the sorption of 17α-ethynylestradiol (EE2) on five soils formed under different redox conditions: an Arenosol (A_20) with fully aerobic conditions, two Gleysol samples (G_20 and G_40) with suboxic and anoxic conditions and two Histosols (H_20 and H_80) with mostly anoxic conditions. The soils were characterized on the basis of total organic carbon (TOC), specific surface area (SSA) and the Fourier transform infrared spectra of the humic acid and humin fractions (the soil remaining after alkali extraction) of the soil. The maximum adsorption capacity of the soils (Qmax) ranged from 10.7 to 83.6 mg/g in the order G_20 > H_20 > G_40 > A_20 > H_80, which reflected the organic matter content of the soils. The sorption isotherms were found to be nonlinear for all the soil samples, with Freundlich n values of 0.45–0.68. The strong nonlinearity found in the adsorption of the H_80 samples could be attributed to their high hard carbon content, which was confirmed by the high aromaticity of the humin fraction. The maximum sorption capacity (Qmax) of the soils did not increase indefinitely as the organic carbon content of the soils rose. There could be two reasons for this: (i) the large amount of organic matter may reduce the number of binding sites on the surface, and (ii) the decrease in SSA with increasing soil OC content may limit the ability to adsorb EE2 molecules. In anaerobic soil samples, where organic matter accumulation is pronounced, the amount of aromatic and phenolic compounds was higher than in better aerated soil profiles. Strong correlations were found between the amount of aromatic and phenolic compounds in the organic matter and the adsorption of EE2 molecules, indicating that π-π interaction and H-bonding are the dominant sorption mechanisms.
17302. 题目: Efficient removal of arsenic from groundwater using iron oxide nanoneedle array-decorated biochar fibers with high Fe utilization and fast adsorption kinetics
期刊: Water Research
作者: Yuanfeng Wei, Shudan Wei, Chengbin Liu, Tao Chen, Yanhong Tang, Jianhong Ma, Kai Yin, Shenglian Luo
摘要: Although Fe-based biochar adsorbents are attractive for removing arsenic from water due to their advantages of costing little and being producible at a large scale, the practical applications of these granular adsorbents are mainly limited by low Fe utilization and slow adsorption kinetics. In this study, iron oxide nanoneedle array-decorated biochar fibers (Fe-NN/BFs) adsorbents have been prepared through a simple hydrothermal reaction. The vertical growth of iron oxide nanoneedle arrays on the surface of biochar fibers maximizes Fe utilization and shortens As diffusion distance, thereby increasing As removal kinetics and capacity. Batch experiments show that the adsorption capacities of Fe-NN/BFs for As(V) and As(III) reach to 93.94 and 70.22 mg/g-Fe at pH 7.0, respectively. As(V) levels (275 μg/L) in groundwater are rapidly reduced (less than 5 min) to below 10 μg/L using Fe-NN/BFs (1 g/L) at pH 6.7. Similar As(III) levels can be reduced to below 10 μg/L within 30 min by Fe-NN/BFs (1.5 g/L). In fixed-bed experiments, the treatment volumes of As(V) and As(III) spiked groundwater reach to 2900 BV (26.2 L) and 2500 BV (22.6 L), respectively, using two columns packed with Fe-NN/BFs in tandem (C0 = 275 μg/L, 2 g of adsorbents in each column). When the As concentration in the influent is reduced to 50 μg/L (As(V): 25 μg/L + As(III): 25 μg/L), the treatment volume using one column reaches up to 11000 BV. The Fe-NN/BFs packed column can be easily regenerated and reused many times. After four regenerations, the treatment volume of As(V) and As(III) were reduced by 10.4% and 22.8%, respectively.
17303. 题目: Total and active soil fungal community profiles were significantly altered by six years of warming but not by grazing
期刊: Soil Biology and Biochemistry
作者: Rongxiao Che, Shiping Wang, Yanfen Wang, Zhihong Xu, Weijin Wang, Yichao Rui, Fang Wang, Jinming Hu, Juan Tao, Xiaoyong Cui
摘要: We examined the responses of total and active soil fungal communities to experimental warming, moderate grazing, and their combination. The six years of field experiments were established in a Tibetan alpine meadow. An infrared heating system was used to simulate warming, and the grazing was conducted by a combination of sheep grazing and clipping. Total and active soil fungal community profiles were determined using MiSeq sequencing of internal transcribed spacer (ITS) DNA and RNA, respectively. Fungal abundance and rDNA transcriptional activity were analyzed through real-time PCR. The results showed that the warming significantly changed the community structures of soil fungi, particularly the active populations. Specific changes in fungal community profiles under the warming scenario included an increase in the proportion of Dothideomycetes (a potential oligotrophic class) and a decrease in the proportion of active plant-symbiotic lineages (e.g., Glomerales). FUNGuild-based functional predictions suggested that warming significantly reduced the proportions of arbuscular mycorrhizal and active saprotrophic fungi. We compared our results to those of another investigation performed at the same location, and found that the ITS-FUNGuild approach was even more sensitive than the 18S rDNA-based method with respect to identifying arbuscular mycorrhizal fungal taxa. Additionally, the warming attenuated the interactions among fungal species, reduced the Chao 1 index of active fungal communities, increased the active fungal community dispersion, and tended to suppress the transcription of fungal rDNA. In contrast, no significant effects of grazing and warming-grazing interactions on soil fungal communities were observed. These findings indicate that global warming may weaken the capacity of soil fungi to decompose organic matter and to facilitate plant nutrient absorption, whereas fungi in Tibetan alpine meadow soils are insensitive to moderate grazing.
17304. 题目: Microstructure and composition of marine aggregates as co-determinants for vertical particulate organic carbon transfer in the global ocean
作者: Joeran Maerz, Katharina D. Six, Irene Stemmler, Soeren Ahmerkamp, and Tatiana Ilyina
摘要: Marine aggregates are the vector for biogenically bound carbon and nutrients from the euphotic zone to the interior of the oceans. To improve the representation of this biological carbon pump in the global biogeochemical HAMburg Ocean Carbon Cycle (HAMOCC) model, we implemented a novel Microstructure, Multiscale, Mechanistic, Marine Aggregates in the Global Ocean (M4AGO) sinking scheme. M4AGO explicitly represents the size, microstructure, heterogeneous composition, density, and porosity of aggregates, and ties ballasting mineral and particulate organic carbon (POC) fluxes together. Additionally, we incorporated temperature-dependent remineralization of POC. We compare M4AGO with the standard HAMOCC version, where POC fluxes follow a Martin curve approach with linearly increasing sinking velocity with depth, and temperature-independent remineralization. Minerals descend separately with a constant speed. In contrast to the standard HAMOCC, M4AGO reproduces the latitudinal pattern of POC transfer efficiency which has been recently constrained by Weber et al. (2016). High latitudes show transfer efficiencies of ≈ 0.25 ± 0.04 and the subtropical gyres show lower values of about 0.10 ± 0.03. In addition to temperature as a driving factor, diatom frustule size co-determines POC fluxes in silicifiers-dominated ocean regions while calcium carbonate enhances the aggregate excess density, and thus sinking velocity in subtropical gyres. In ocean standalone runs and rising carbon dioxide (CO2) without CO2 climate feedback, M4AGO alters the regional ocean-atmosphere CO2 fluxes compared to the standard model. M4AGO exhibits higher CO2 uptake in the Southern Ocean compared to the standard run while in subtropical gyres, less CO2 is taken up. Overall, the global oceanic CO2 uptake remains the same. With the explicit representation of measurable aggregate properties, M4AGO can serve as a testbed for evaluating the impact of aggregate-associated processes on global biogeochemical cycles, and, in particular, on the biological carbon pump.
17305. 题目: Volatile methanol and acetone additions increase labile soil carbon and inhibit nitrification
作者: Steven G. McBride, Ernest D. Osburn, John E. Barrett, Michael S. Strickland
摘要: Recent efforts to understand the contribution of low-molecular weight compounds to carbon dynamics in soil ecosystems has resulted in a framework that suggests that low-molecular weight, labile carbon compounds can be directly assimilated by microbial biomass before being stabilized on soil colloids. However, this model primarily focuses on dissolved organic matter inputs and overlooks the potential importance of volatile organic compounds (VOCs). Here we determined the effects of two VOCs commonly emitted from soil and decomposing leaf litter (methanol, and acetone) on soil respiratory dynamics during a 28-day lab experiment. At the end of the experiment we quantified carbon and nitrogen concentrations in dissolved organic matter, microbial biomass, particulate organic matter, mineral associated organic matter, the labile carbon pool, and we quantified nitrifying microorganism abundance. Our results demonstrate that VOCs (i.e. methanol and acetone) increase soil respiration, contribute to labile soil C, and inhibit nitrification. Our VOC additions resulted in respiration spikes 4.1–5.5-fold greater than the control for acetone and methanol, respectively, though respiration returned back to control levels within 144 h after additions. Our VOC additions resulted in a 1.6–1.7-fold increase in labile soil carbon, suggesting that litter-derived VOCs could enter soil C pools following microbial metabolism. Additionally, soils exposed to VOCs contained ~ 2.25-fold less total dissolved nitrogen, and ~ 34–220-fold less nitrate. Ammonia oxidizing archaea were ~ 1.5 fold less abundant in VOC treated soils than in the control. After VOC additions were ceased, nitrate levels increased at approximately the same rate in all treatments, suggesting an inhibitory effect of methanol and acetone on nitrifying microorganisms. These results indicate that common decomposition derived VOCs play an important yet under-recognized role in driving the formation of soil organic matter as well as increasing the immobilization of nitrogen in soil ecosystems.
17306. 题目: A novel Biochar modified by Chitosan-Fe/S for tetracycline adsorption and studies on site energy distribution
期刊: Bioresource Technology
作者: Juanli Liu, Baiqin Zhou, Hong Zhang, Juan Ma, Bin Mu, Wenbo Zhang
摘要: A novel wasted sludge-based Biochar modified by Chitosan and Fe/S (BCFe/S) was prepared for tetracycline (TC) removal from water. To investigate the similarities and differences in adsorption behaviors between Biochar and BCFe/S, characterization, kinetics, isotherms and thermodynamics were discussed. The studies on site energy distribution (SED) were also presented. The results showed that the maximum TC adsorption amount was 51.78 mg/g for Biochar, while it was 183.01 mg/g for BCFe/S-4. Meanwhile, electrostatic attraction, π-π stacking, pore filling, silicate bonding and hydrogen bonding were the main adsorption mechanisms for TC removal by Biochar. Besides above mechanisms, chelating and ion exchange were also accounted for adsorption mechanisms for TC uptake by BCFe/S-4. Moreover, SED results revealed that the surface of Biochar was more homogeneous while the surface of BCFe/S-4 was more heterogeneous at higher temperature. Findings of this work could offer valuable information in designing adsorbents and investigating adsorption mechanisms.
17307. 题目: Seasonal organic matter dynamics in a temperate shelf sea
期刊: Progress in Oceanography
作者: Clare E. Davis, Sabena Blackbird, George Wolff, Malcolm Woodward, Claire Mahaffey
摘要: Organic matter (OM) plays an important role in productive shelf seas and their contribution to global carbon (C) and nutrient cycles. We investigated dissolved and particulate OM (DOM and POM, respectively) dynamics over a seasonal cycle in the Celtic Sea. The quantity of OC was largest during the spring bloom and lowest in autumn. DOM was always C rich relative to the POM pool and the Redfield ratio (106C:16N:P). There was clear decoupling between C, N and P and the response of OM composition to different seasons and nutrient statuses of the microbial community. The C:P stoichiometry was much more variable than the C:N stoichiometry, which was near constant. Downward OC fluxes were dominated by POM during bloom events and DOM during the stratified summer. In terms of partitioning, 92–96% of OC was in the DOM pool throughout sampling, which given its high C:N (12.4–17) suggests it was an efficient vehicle for potential off-shelf export of C during winter mixing.
17308. 题目: Seasonal changes in plankton respiration and bacterial metabolism in a temperate shelf sea
期刊: Progress in Oceanography
作者: E. Elena García-Martín, Chris J. Daniels, Keith Davidson, Clare E. Davis, Claire Mahaffey, Kyle M.J. Mayers, Sharon McNeill, Alex J. Poulton, Duncan A. Purdie, Glen A. Tarran, Carol Robinson
摘要: The seasonal variability of plankton metabolism indicates how much carbon is cycling within a system, as well as its capacity to store carbon or export organic matter and CO2 to the deep ocean. Seasonal variability between November 2014, April 2015 and July 2015 in plankton respiration and bacterial (Bacteria + Archaea) metabolism is reported for the upper and bottom mixing layers at two stations in the Celtic Sea, UK. Upper mixing layer (UML, >75 m in November, 41–70 m in April and ∼50 m in July) depth-integrated plankton metabolism showed strong seasonal changes with a maximum in April for plankton respiration (1.2- to 2-fold greater compared to November and July, respectively) and in July for bacterial production (2-fold greater compared to November and April). However UML depth-integrated bacterial respiration was similar in November and April and 2-fold lower in July. The greater variability in bacterial production compared to bacterial respiration drove seasonal changes in bacterial growth efficiencies, which had maximum values of 89% in July and minimum values of 5% in November. Rates of respiration and gross primary production (14C-PP) also showed different seasonal patterns, resulting in seasonal changes in 14C-PP:CRO2 ratios. In April, the system was net autotrophic (14C-PP:CRO2 > 1), with a surplus of organic matter available for higher trophic levels and export, while in July balanced metabolism occurred (14C-PP:CRO2 = 1) due to an increase in plankton respiration and a decrease in gross primary production. Comparison of the UML and bottom mixing layer indicated that plankton respiration and bacterial production were higher (between 4 and 8-fold and 4 and 7-fold, respectively) in the UML than below. However, the rates of bacterial respiration were not statistically different (p > .05) between the two mixing layers in any of the three sampled seasons. These results highlight that, contrary to previous data from shelf seas, the production of CO2 by the plankton community in the UML, which is then available to degas to the atmosphere, is greater than the respiratory production of dissolved inorganic carbon in deeper waters, which may contribute to offshore export.
17309. 题目: Application of biochar and its composites in catalysis
作者: Honghong Lyu, Qianru Zhang, Boxiong Shen
摘要: With a wide range of raw materials, low cost and large specific surface area, biochar has been widely used in environmental remediation. However, the biochar has a saturated adsorption capacity when it is used as a pollutant adsorbent. Recent efforts have been made to prepare biochar and biochar-based catalysts with enhanced catalytic properties to expand their potential applications. The environmental persistent free radicals (EPFRs) of biochar could react with O2 to induce hydroxyl radicals (•OH) without the addition of oxidants. When oxidants were added, biochar and biochar-based catalysts could activate them to generate •OH and sulfate radicals (SO4•−), respectively. Moreover, biochar could act as an electron acceptor to improve the photodegradation capacity of catalysts. With reference to the information regarding biochar and biochar-based catalysts, this work provides a critical review on recent research development as follows: 1) the preparations of various types of biochar and biochar-based catalysts are summarized; 2) the effects of the synthetic conditions and transition metals on the catalytic activity of biochar-based catalysts are discussed; (3) methods for characterizing the active sites of the biochar-based catalysts are described; and (4) the environmental applications of biochar and biochar-based catalysts are discussed with regards to three aspects based on the interaction mechanisms, namely, oxidation, reduction, and photocatalysis. The synthesis conditions and loading of metal/metal-free catalyst are key parameters controlling the catalysis activity of biochar and biochar-based catalysts. This review provides new insights into the application of biochar in catalysis. Key challenges and further research directions are proposed as well.
17310. 题目: Spectrum evolution of dissolved aromatic organic matters (DAOMs) during electro-peroxi-coagulation pretreatment of coking wastewater
期刊: Separation and Purification Technology
作者: Xin Zhou, Zilong Hou, Jingjing Song, Lin Lv
摘要: Enormous existence of dissolved aromatic organic matters (DAOMs) is considered to be a major cause that coking wastewater is hardly degraded. In this study, an advanced electro-chemical process i.e. electro-peroxi-coagulation (EPC) was developed as a pretreatment for efficiently degrading DAOMs and improving the biodegradability of the raw coking wastewater. Gas chromatography-mass spectrometry (GC-MS) also confirmed that most of DAOMs (phenolics, heterocycles, polycyclic aromatic hydrocarbons, benzenes, organic nitriles and anilines) could be effectively decomposed by EPC pretreatment. Ultraviolet visible (UV-Vis), Fourier transform infrared spectroscopy (FTIR) and excitation-emission matrix (EEM) consistently found remarkable spectrum variations of DAOMs in the first 15 min, while spectrum changes became gentle until 2 h. The spectrum evolution of DAOMs suggests the strong attacks on the benzene rings and unsaturated bonds of DAOMs occurs initially and then low molecule intermediates are further degraded. Therefore, EPC should be a feasible option for coking wastewater pretreatment based on the combination of electro-oxidation and electro-precipitation.
17311. 题目: Coupled retention of bovine serum albumin and NOM by porous membranes
期刊: Separation and Purification Technology
作者: Lanlan Qin, Haiou Huang
摘要: Coupled retention of natural organic matter (NOM) is an important process in membrane water treatment. A mechanistic understanding is lacking due to the complex nature of NOM. In this study, filtration experiments were conducted with the mixture of bovine serum albumin (BSA) and Suwannee River NOM (SRNOM) through different pore-sized membranes. A macroscopic depth filtration theory was utilized for analyzing the underlying mechanisms. The results showed the importance of BSA-SRNOM interactions on NOM retention. At a neutral pH of 7.0, the co-existing SRNOM reduced BSA retention by up to 24% by mitigating concentration polarization and inner-pore BSA deposition. Meanwhile, the presence of BSA elevated SRNOM retention by up to 23% because of SRNOM adsorption onto the deposited BSA, as well as enhanced steric hindrance and concentration polarization effect. Furthermore, the reduction of solution pH to 3.7 enhanced BSA-SRNOM interactions that favored multilayer BSA/SRNOM deposition. As a result, BSA and SRNOM retention increased by 54% and 79 %, 78% and 37 %, and 48% and 10% for membranes having pore radii of 7.5 nm, 15 nm and 25 nm, respectively. This study demonstrated that the interplay of concentration polarization, steric hindrance, and inner-pore deposition governed NOM retention by porous membranes.
17312. 题目: Long-term stacking coal promoted soil bacterial richness associated with increased soil organic matter in coal yards of power plants
期刊: Journal of Soils and Sediments
作者: Congcong Shen, Dawei Ma, Ruibo Sun, Benyao Zhang, Delin Li, Yuan Ge
摘要: Purpose: Coal exploitation inevitably brings a chain of ecological problems, e.g., land destruction and biodiversity decrease. Most previous studies have investigated the ecological effect of coal mining process and the ecological restoration after coal mining practice. However, no study has concerned about the potential influence of long-term stacking coal process on soil microbial communities, the pivotal components to maintain the health of terrestrial ecosystems. This study aims to investigate the influence of long-term stacking coal on soil microbial communities, as well as the time effect. Materials and methods: We collected soil samples from coal yards of four power plants (representing four stacking time: 10, 28, 31, and 71 years) in Huainan city. Soils in the lawn near each coal yard were also selected as control at four sites. Soil microbial communities were analyzed via 16S and 18S rRNA gene sequencing. Results and discussion: Our results showed that long-term stacking coal significantly (P < 0.05) increased soil organic matter (SOM), and thus facilitated soil bacterial richness and the shifts of bacterial community composition. We also detected significant (P < 0.05) increase of SOM, bacterial richness, and community dissimilarity with stacking time, indicating a substantial time effect. Meanwhile, predicted functional data implied that stacking coal activated anaerobic microbial communities by forming an anaerobic environment in soils. Conclusions: Together, these data provide basic knowledge of the potential influence of long-term stacking coal on soil microbial communities and reinforce the role of SOM in shaping bacterial community composition and richness.
17313. 题目: The Sources of Organic Matter in Seagrass Sediments and Their Contribution to Carbon Stocks in the Spermonde Islands, Indonesia
期刊: Aquatic Geochemistry
作者: Yusmiana P. Rahayu, Tubagus Solihuddin, Mariska A. Kusumaningtyas, Restu Nur Afi Ati, Hadiwijaya L. Salim, Tim Rixen, Andreas A. Hutahaean
摘要: Seagrass ecosystems have a potential role in climate change mitigation due to their ability to store high amount of carbon, particularly in the sediment. Studying the factors and mechanisms responsible for this storing capacity is essential to understand seagrass carbon sink function. Therefore, in this study, we identified the sources of organic carbon (Corg) in seagrass sediments and the implication to Corg stocks from four islands in the Spermonde Islands that located at different zones. We used the Bayesian stable isotope mixing model to estimate the proportional contribution of different sources to sediment carbon. Seagrass meadows that located in adjacent to high anthropogenic activities (deforestation and aquacultures) with direct exposure to wave actions, such as on the Bauluang Island, accumulated organic carbon that derived from multiple sources, where phytoplankton contributed the highest, while on the other three islands that are relatively protected from wave actions, the highest contribution (~ 75%) was from autochthonous production (seagrass-derived). Sediment Corg stocks vary spatially, ranging from 11.9 to 32.1 Mg C ha−1 (based on the obtained depth of 20–55 cm), or 40.5 to 83.5 Mg C ha−1 if extrapolated to 1 m depth. The variability of sediment properties and Corg stocks in this study is not solely determined by the geographical differences (inshore, nearshore and offshore islands), but also influenced by other local factors such as hydrodynamics that control the distribution of carbon sources, anthropogenic pressures and species composition. These factors should be taken into account when developing coastal management strategies, as efforts are being undertaken to include coastal ecosystems (including seagrass ecosystems) on the National Green House Gasses Reduction Strategy.
17314. 题目: Sulfur controlled cadmium dissolution in pore water of cadmium-contaminated soil as affected by DOC under waterlogging
作者: Guoxi Wang, Zhengyi Hu, Songyan Li, Yan Wang, Xiaolei Sun, Xiangru Zhang, Meng Li
摘要: Cadmium (Cd) precipitation and dissolution in pore water is associated with dissolved organic carbon (DOC)-induced reduction-oxidation of sulfur (S) under waterlogging and is vital for controlling the bioavailability in paddy soil. A 120-day soil incubation experiment, including application of sulfur (S, 30 mg kg−1) and wheat straw (W, 1.0%) alone or in combination (W + S) into Cd-contaminated paddy soil under waterlogging, was conducted to investigate the dynamic of dissolved Cd and its relationship with DOC, S2−, Fe2+, pH, Eh and pe + pH in soil pore water. The results showed that the lowest dissolved Cd concentration was observed in the W + S-treated soil pore water among all treatments when the soil Eh remained at lower values during the period of 15–60 days of incubation, which could be attributed to CdS precipitation and/or co-precipitation of Cd absorbed by FeS2 because of the reduction in sulfur. The application of S resulted in a Cd rebound in the pore water irrespective of W addition when the Eh began to increase from its lowest values during the period of 45–75 days of incubation, and SOB genera were observed in the S added soil. This could be attributed to re-dissolution of the precipitated Cd in soils under the SOB-driven oxidation of sulfide such as CdS and FeS2. In conclusion, DOC-driven reduction-oxidation of sulfur controls Cd dissolution in the pore water of Cd-contaminated paddy soil under waterlogging conditions. Further studies are required to investigate the interaction of sulfur and SOM-induced DOC on Cd bioavailability in rice-planted paddy soils.
17315. 题目: Low-molecular-weight organic acids enable biochar to immobilize nitrate
作者: Natalie Heaney, Emem Ukpong, Chuxia Lin
摘要: Batch experiments were conducted using two biochar materials produced from different feedstocks to examine the behavior of solution-borne nitrate in the presence and absence of three model low-molecular weight organic acids (LMWOAs). The results showed that the biochar materials alone were not able to remove the solution-borne nitrate. LMWOAs caused protonation of the biochar surfaces and consequently enabled the biochar materials to adsorb nitrate from the solution. Different types of LMWOA had different capacities to immobilize solution-borne nitrate. Over 80% of the solution-borne nitrate could be removed within 72 h in the presence of citric acid or malic acid. By comparison, removal rate of nitrate was lower in the presence of oxalic acid, possibly due to competition of oxalate ion with nitrate for the available adsorption sites on the biochar surfaces. Nitrate adsorption onto the MSP700 biochar in the presence of all three-LMWOAs followed first order and second order kinetics, suggesting that the immobilization of nitrate involved complex interplay of physisorption and chemisorption. Nitrate adsorption onto RH700 biochar in citric and malic acid treatment systems followed second order kinetics. In the presence of oxalic acid for both biochar materials, nitrate adsorption showed perfect correlation R2 = 1 for both models.
17316. 题目: pH dependence of the binding interactions between humic acids and bisphenol A - A thermodynamic perspective
期刊: Environmental Pollution
作者: Li-hong Gan, Zi-run Yan, You-fei Ma, Yu-ying Zhu, Xiu-yan Li, Juan Xu, Wei Zhang
摘要: The wide application of bisphenol A (BPA) leads to the emergence of BPA residuals in natural water environments. Dissolved organic matter (DOM) existed in water can bind with BPA, hence influencing the migration and transformation of BPA in aquatic environments. pH is a crucial factor governing the binding interactions between DOM and BPA. However, the mechanisms driven the binding process under different pH conditions are still unclear. In this study, the interactions between BPA and humic acids (HA), a primary component of DOM, are investigated over a wide pH range of 3–12 by integrating fluorescence quenching, dynamic light scattering and microcalorimetry. pH dependence of the binding interactions between HA and BPA are interpreted from a thermodynamic perspective. The results indicate that HA can spontaneously interact with BPA to form a stable HA-BPA complex. With the increasing pH, the binding interactions change from entropy driven to entropy-enthalpy co-driven. Hydrophobic force dominate the binding interactions under acidic condition. The synergy of hydrophobic force and hydrogen bond promotes the binding process under neutral condition. Under alkaline condition, electrostatic repulsion participates the binding process in addition to hydrophobic force and hydrogen bond, weakening the binding strength. Therefore, neutral pH is favorable for HA to bind with BPA, consequently enhancing the dissolution of BPA in natural water bodies. The results are beneficial to better understand the pH dependent distribution of BPA in aquatic environments.
17317. 题目: Sludge dewaterability: The variation of extracellular polymeric substances during sludge conditioning with two natural organic conditioners
期刊: Journal of Environmental Management
作者: Marie Christine Amie Sene Faye, Kai Kai Zhang, Sun Peng, Yanrong Zhang
摘要: To assess the characteristics of Extracellular Polymeric Substances during natural organic conditioners for sludge treatment, Moringa oleifera (MO) and chitosan (CTS) were used as conditioners. The findings of this study show that despite the high EPS content due to the fact that this component is not destroyed upon conditioning, sludge conditioned with MO and CTS displayed efficient and improved dewaterability. MO and CTS showed the same mechanism of action by protonation of the negatively charged EPS and reduction of electrostatic repulsions between sludge flocs, thus enhancing sludge filterability by neutralizing and settling. The effect of MO and CTS on EPS lies in their ability to neutralize EPS, settling them. MO and CTS neutralize and aggregate the EPS, hence improving sludge dewaterability. The results indicate that CTS can impact the EPS quantity and quality while MO impacts the EPS quality. Understanding the impact of MO and CTS on sludge EPS can help elucidate the mechanism of their dewaterability efficiency.
17318. 题目: Composition change and adsorption performance of EPS from Bacillus vallismortis sp. induced by Na2S
期刊: Ecotoxicology and Environmental Safety
作者: Qiuhua Li, Weifeng Song, Mengge Sun, Jiayao Li, Zefeng Yu
摘要: Sodium sulfide (Na2S) was used as an inducer to regulate the components of Bacillus vallismortis sp. EPS (Extracellular Polymeric Substances). The main objective of this study was to improve the content of sulfhydryl protein and the adsorption property of EPS to Zn (Ⅱ) that as an typical heavy metal. The results showed that the maximum EPS production of 105.58 mg/g VSS coupling with doubled increase in protein in which the contant of -SH increased by 48.2% from 104.15 to 154.36 μmol/L were recorded in the presence of 20 mg/L Na2S. Under this condition, the adsorption capacity of S-EPS (EPS with added exogenous Na2S) for Zn (Ⅱ) was highest. The kinetics of the adsorption process of Zn (Ⅱ) by the S-EPS can be well fitted by the Langmuir isotherm model and the theoretical maximum adsorption amount of 979.09 mg/g EPS could be obtained. The results of 3D-EEM and FTIR analyses, illustrated that -SH, CO, and N-H/C-N played major roles in the removal of Zn (Ⅱ) by S-EPS. The results obtained in this study demonstrated that the addition of sulfur source could increase the content of sulfhydryl protein, and effectively regulate the content of chemical composition, expecially for the sulfhydryl of EPS, and thereby greatly improving the removal efficiency of heavy metals, which showed a great application prospect in the prevention and control of heavy metal pollution.
17319. 题目: Magnetic Biochar Derived from Biosolids via Hydrothermal Carbonization: Enzyme Immobilization, immobilized-enzyme kinetics, environmental toxicity
期刊: Journal of Hazardous Materials
作者: He Zhang, Anthony G. Hay
摘要: Magnetic and nonmagnetic biochar (MBC & BC) were produced from biosolids under hydrothermal conditions and characterized in order to understand surface chemistry impacts on enzyme immobilization and activity. Peak surface pore size of MBC was 180 nm and that of BC was 17 nm. Despite similar surface area (≈ 49 m2/g) MBC immobilized more laccase (99 mg/g) than biochar (31 mg/g). For horseradish peroxidase (HRP), the two biochars had similar immobilization capacity (≈ 65 mg/g). Laccase and HRP on MBC had 47.1 and 18.0% higher specific activity than on BC, respectively. The matrix activity of MBC-laccase (33.3 U/mg support) was 3.7-fold higher than BC-laccase (8.8 U/mg support) and higher than the same amount of free laccase (30.2 U) at pH 3.0 (P < 0.05). Although MBC had its own peroxide oxidation activity (104.1 and 165.9 U/mg biochar at pHs 5&6) this only accounted for 16.7 and 20.4 % of the total MBC-HRP activity respectively. After 10 wash cycles, MBC still retained 79.3% and 60.3% of laccase and HRP activity, respectively. Additionally, MBC had lower acute toxicity, suggesting that it is relative benign from an environmental perspective.
17320. 题目: Photodegradation of Fludioxonil and Other Pyrroles: The Importance of Indirect Photodegradation for Understanding Environmental Fate and Photoproduct Formation
期刊: Environmental Science & Technology
作者: Jennifer N Apell, Nicholas C. Pflug, Kristopher McNeill
摘要: Fludioxonil is a pyrrole-containing pesticide whose registration as a plant protection product is currently under review in the United States and Europe. There are concerns over its potential persistence and toxicity in the aquatic environment; however, the pyrrole moiety represents a potential reaction site for indirect photodegradation. In this study, the direct and indirect photodegradation of fludioxonil, along with pyrrole, 3-cyanopyrrole, and 3-phenylpyrrole, were investigated. Results showed that pyrrole moieties are capable of undergoing direct photoionization and sensitized photooxidation to form radical cation species, which then likely deprotonate and react with dissolved oxygen. Additionally, pyrrole moieties can undergo reactions with singlet oxygen (1O2). Furthermore, the presence of electron-withdrawing or -donating substituents substantially impacted the reaction rate with 1O2 as well as the one-electron oxidation potential of the pyrrole that dictates reactions with triplet states of dissolved organic matter (3CDOM*). For fludioxonil, which can undergo both direct and indirect photodegradation, the reaction rate constant with 1O2 alone resulted in a predicted t1/2 < 2 days in waters under sunlit near-surface conditions, suggesting it will not be persistent in aquatic systems. These results are useful for evaluating the environmental fate of fludioxonil as well as other pyrrole compounds.