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25321. 题目: Spatio-temporal heterogeneity in extracellular enzyme activities tracks variation in saprotrophic fungal biomass in a temperate hardwood forest
文章编号: N19091501
期刊: Soil Biology and Biochemistry
作者: Meghan G. Midgley, Richard P. Phillips
更新时间: 2019-09-15
摘要: Saprotrophic fungi are the dominant producers of organic matter-degrading extracellular enzymes in forest soils, but the extent to which they drive spatio-temporal variation in enzyme activities is unclear. We quantified the relationships between saprotrophic fungal biomass and enzyme activities in a mature temperate hardwood forest by placing soil-filled ingrowth bags inside trenches. Trenches were located in replicate stands (n = 7) dominated by either arbuscular mycorrhizal (AM)- or ectomycorrhizal (ECM)-associated tree species, which reflect differences in soil substrate quality and nutrient availability. Additionally, we assessed the extent to which the relationships between saprotrophic fungal biomass and enzyme activities varied across seasons and were altered by experimental nitrogen (N) addition. Overall, both fungal production and enzyme activities differed between mycorrhizal types and across seasons, but were unaffected by N addition. Additionally, enzyme activities exhibited strong, positive relationships with saprotrophic fungal biomass. However, the relative production of carbon (C)-degrading enzymes was greater in stands dominated by AM-associated trees in the late growing season, and the relative production of N-degrading enzymes was greater in the late growing season across both AM- and ECM-dominated forest stands. These patterns reflected tree- and season-driven changes in microbial C and N limitation. As such, while the common assumption that microbial biomass and enzyme activities are positively correlated is robust for saprotrophic fungi, enzyme produced per unit biomass may not be consistent among stands and across seasons.
25322. 题目: Post-treatment of paint industry effluents by filtration using Andropogon biochar (Andropogon gayanus Kunth cv. Planaltina)
文章编号: N19091417
期刊: Environmental Science and Pollution Research
作者: Argemiro L. Pedrosa, Marcelo M. Pedroza, Grasiele S. Cavallini
更新时间: 2019-09-14
摘要: This study evaluates the filtration potential of the biomass obtained from Andropogon grass (Andropogon gayanus Kunth cv. Planaltina) that was converted to biochar by pyrolysis. The biochar is used in filtration systems for the post-treatment of paint industry effluents. The biomass is characterized by elemental analysis (CHSN-O), determination of specific compounds (cellulose/hemicellulose/lignin), FTIR, and SEM. The produced biochar is characterized by SEM, TGA, and surface area analysis. The efficiency of the filters is evaluated by the following parameters: color, turbidity, removal of total solids (suspended and sedimentable), chemical oxygen demand (COD), and metals (Al, Cu, Zn, Co, Cd, and Cr(VI)). Over 99% removal of aluminum, cadmium, and hexavalent chromium is achieved. Moreover, almost 100% of COD and solids are removed, whereas turbidity and color are reduced by over 90%.
25323. 题目: Gradients of labile carbon inputs into the soil surrounding wood ant nests in a temperate forest
文章编号: N19091416
期刊: Biology and Fertility of Soils
作者: Veronika Jílková, Kateřina Jandová, Anna Vacířová, Jaroslav Kukla
更新时间: 2019-09-14
摘要: Wood ants are common in temperate forests, and while building their nests and foraging for food, they transfer large amounts of organic matter and nutrients. Here, we tested the hypothesis that wood ants generate natural gradients of labile carbon (C) inputs into the soil surrounding their nests. We selected five medium-sized wood ant (Formica aquilonia) nests in a coniferous temperate forest and established sampling points at distances of 4, 30 and 70 m from each nest. Throughfall (honeydew + aboveground vegetation leachates) and litterfall were collected regularly during a vegetative season and were analysed for labile organic C content. In addition, soil from the organic horizon (Oe + Oa), surface mineral horizon (A) and subsoil mineral horizon (B) was collected and analysed for organic matter and nutrient contents. The labile C input in throughfall increased with distance from the nest (it was 1.5-fold greater at 70 m than at 4 m). C input changed during the vegetative season and was highest in June. Litterfall was not affected by the distance from the nest. Organic matter and nutrient contents were unaffected by distance from the nest in surface soil horizons but were significantly higher near the nest (4 m) than 70 m from the nest in the subsoil mineral horizon, suggesting that surface soils are less affected by the labile C inputs than subsoils. Finally, we suggest that the gradients in labile C input surrounding wood ant nests can be used to study the effects of labile C input changes on soil properties.
25324. 题目: Coadsorption of Cu(II) and tylosin/sulfamethoxazole on biochar stabilized by nano-hydroxyapatite in aqueous environment
文章编号: N19091415
期刊: Chemical Engineering Journal
作者: Zhen Li, Miao Li, Zhaoyan Wang, Xiang Liu
更新时间: 2019-09-14
摘要: Antibiotics and heavy metals are frequently detected simultaneously in water environment. In this study, a biochar stabilized by nano-hydroxyapatite (nHAP@biochar) was used for the coadsorption of tylosin (TYL)/sulfamethoxazole (SMX) and Cu(II) in aqueous environment, which was well suited for real water samples. The physicochemical properties of nHAP@biochar were characterised by SEM image, zeta potential, FTIR, BET analysis, XPS and XRD. The pseudo-second-order model was better fit for the sorption kinetics data. Background electrolytes, ionic strength, humic acid (HA) and addition sequences presented a significant effect on the adsorption of TYL/SMX and Cu(II) when with or without Cu(II). The adsorption of TYL and Cu(II) increased with the increasing of ionic strength and HA, and compared with TYL, the influence on SMX was not obvious. Adsorption results exhibited that TYL obviously enhanced the Cu(II) adsorption capability and Cu(II) obviously enhanced the SMX adsorption capability. According to the results of FTIR and XPS, H-bond may be one of the main interactions of TYL with nHAP@biochar adsorption and weak π-π interactions and H-bond were two of the main interaction of SMX. TYL/SMX-Cu complexes were formed. In the system, the complexes were more on the formation of nHAP@biochar-TYL-Cu and nHAP@biochar-Cu-SMX, rather than on nHAP@biochar-Cu-TYL and nHAP@biochar-SMX-Cu, respectively.
25325. 题目: Broadened operating pH range for adsorption/reduction of aqueous Cr(VI) using biochar from directly treated jute (Corchorus capsularis L.) fibers by H3PO4
文章编号: N19091414
期刊: Chemical Engineering Journal
作者: Mingxin Chen, Feifei He, Dongwen Hu, Chongzhuo Bao, Qiang Huang
更新时间: 2019-09-14
摘要: Biochar has attracted much attention as a green cost-effective adsorbent for heavy metal removals. However, previous studies generally found that biochar was only effective in a narrow low pH range for Cr(VI) removal, and less attention was paid to biochar which can be effectively operated in a wider range of pH. This study showed that the jute fiber-based biochar pretreated H3PO4 can availably remove and reduce Cr(VI) to Cr(III) in wastewater over a broadened operating pH range of 1–6, in which the intrinsic pH of Cr(VI) solution was included. For this, XRD, Raman, SEM, elemental analysis and N2 adsorption- desorption techniques were utilized to characterize the structure and compositions of the biochars. FTIR, XPS, Boehm titration and zeta potential measurements were performed to determine the surface group and charge distributions. It was revealed that in comparison with the biochar activated by KOH, H3PO4-treated biochar offered sufficient acidic groups such as phosphonic acid and carboxyl on the surface, from which the supplied protons could maintain the pH within a stable range of 1.9–3.4. XPS analysis exhibited that the electron-rich C–O, P–O and C–P bonds acted electron donating moieties to reduce high potential Cr(VI). Cr(VI) uptake experiments showed that Freundlich multilayer chemisorption occurred on the heterogeneous surface. Langmuir-Hinshelwood kinetic model suggested the surface reaction was the rate-controlling step. The examination for simulated samples confirmed that the H3PO4-treated biochar could control Cr(VI) pollution at the inherent pH in the environment.
25326. 题目: A facile foaming-polymerization strategy to prepare 3D MnO2 modified biochar-based porous hydrogels for efficient removal of Cd(II) and Pb(II)
文章编号: N19091413
期刊: Chemosphere
作者: Zhiying Wu, Xiaoxiao Chen, Baoling Yuan, Ming-Lai Fu
更新时间: 2019-09-14
摘要: A novel three dimensional MnO2 modified biochar-based porous hydrogel (MBCG) was fabricated to overcome the low sorption capacity and difficulty in solid-liquid separation of biochar (BC) for Cd(II) and Pb(II) removal. BC was initially modified by a rapid redox reaction between KMnO4 and Mn(II) acetate, and then incorporated into a polyacrylamide gel network via a rapid and facile free-radical polymerization. A foaming method was deliberately introduced during the fabrication to establish interpenetrated porous structure inside the network. Various characterizations were employed to examine the morphology, porous structures, chemical compositions, and mechanical properties of the samples. Adsorption performance of MBCG on Cd(II) and Pb(II) (isotherms and kinetics) as well as its desorption and reusability were also investigated. The results indicated that MnO2 modified biochars (MBC) were successfully introduced and homogeneously distributed in the porous bulk hydrogel, endowing MBCG with more uniform pore structure, excellent thermostability, remarkable mechanic strength, and superior adsorption performance. The maximum Langmuir adsorption capacity on Cd(II) and Pb(II) is 84.76 and 70.90 mg g−1, respectively, which is comparable or even larger than that of MBC. More importantly, MBCG can be rapidly separated and easily regenerated with an excellent reusability, which could retain 92.1% and 80.5% of the initial adsorption capacities of Cd(II) and Pb(II) after five cycles. These new insights make MBCG an ideal candidate in practical applications in water treatment and soil remediation contaminated with various heavy metals.
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25327. 题目: Tracking and analysis of DBP precursors’ properties by fluorescence spectrometry of dissolved organic matter
文章编号: N19091412
期刊: Chemosphere
作者: Zihong Fan, Hailing Yang, Shuangfei Li, Xin Yu
更新时间: 2019-09-14
摘要: Disinfection by-products (DBPs) play a significant role in human health. Identification of the precursor of DBPs, which constitutes dissolved organic matter (DOM), can help optimize the processes in a drinking water treatment plant (DWTP). This is very important for obtaining more safe water. In this context, a one-year study was performed in a DWTP. Fluorescence spectra of DOM were quantified for determining DOM composition and properties, and the corresponding DBPs formation was analyzed. Hydrophobic neutral and acidic compounds were found to be the two predominant substances forming DBPs, which also were dominant in the DOM. Coagulation and sedimentation were not effective in DOM elimination. Besides, sand filtration caused organic compounds to increase by 14.8% on average, especially 28.59% for aromatic protein II and 18.7% for soluble microbial product-like compounds, which was due to metabolism by microorganisms present in the filter. Carbonaceous DBPs were elevated from 34.8 μg/L in source water to 42.5 μg/L in effluent, along with organic compounds increasing in filtration, and nitrogenous DBPs were under detection in winter. All DBPs appeared at a high level in summer. Accordingly, enhanced coagulation process and measures that can avoid the release of organic compounds during filtration have been suggested. As the source water was rarely affected by human activities in the study area and owing to the wide use of traditional treatment process, the data of this research can be regarded as environmental background values and the results are considered as a significant reference.
25328. 题目: Characterization of fluorescent dissolved organic matters in metalworking fluid by fluorescence excitation-emission matrix and high-performance liquid chromatography
文章编号: N19091411
期刊: Chemosphere
作者: Jian Shen, Bo Liu, Jing Wu, Yidi Chai, Cheng Cheng, Chuanyang Liu, Rui Yan, Muhammad Farooq Saleem Khan
更新时间: 2019-09-14
摘要: In recent years, precise environment supervision has gradually become vital in water pollution control, which requires the clear identification of dissolved organic matters (DOM) in wastewater. Metalworking fluid (MWF) is a type of wastewater with high toxicity. Over ten million m3 of MWF is discharged per year. However, its DOM characteristics have not yet been systematically investigated. Therefore, in this study, the fluorescent DOM (FDOM) of MWF was firstly characterized by excitation-emission matrix-parallel factor analysis (EEM-PARAFAC) and high-performance liquid chromatography (HPLC). Three fluorescent components (C1-C3) of the MWF from three metalworking plants (BO, TH, and YD) were identified. The peaks measured for C1 and C3 were attributed to tryptophan-like (Peak T) and humic/fulvic acid-like (Peak A + C) peaks, respectively, and the peaks at C2 were identified as humic-like (Peak A + M) or tryptophan-like (Peak T) peaks. There were differences in the C2 and C3 components of MWF from the three metalworking plants. The FDOM of MWF from the three metalworking plants exhibited similar polarity, but different apparent molecular weight distributions. In addition, the highest intensities of the three fluorescent peaks were sensitive to variations in the pH, humic acid (HA) concentrations, and metal ion levels (Cu2+, Fe3+, and Ni2+). The findings of this study not only indicate the FDOM characteristics of MWF, but also provide a promising method and valuable guidance for the practical monitoring of MWF in natural water bodies.
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25329. 题目: Role of surface functionalities of nanoplastics on their transport in seawater-saturated sea sand
文章编号: N19091410
期刊: Environmental Pollution
作者: Zhiqiang Dong, Ling Zhu, Wen Zhang, Rui Huang, XiangWei Lv, Xinyu Jing, Zhenglong Yang, Junliang Wang, Yuping Qiu
更新时间: 2019-09-14
摘要: The transport and retention of nanoplastics (NP, 200 nm nanopolystyrene) functionalized with surface carboxyl (NPC), sulfonic (NPS), low-density amino (negatively charged, NPA−), and high-density amino (positively charged, NPA+) groups in seawater-saturated sand with/without humic acid were examined to explore the role of NP surface functionalities. The mass percentages of NP recovered from the effluent (Meff) with a salinity of 35 practical salinity units (PSU) were ranked as follows: NPC (19.69%) > NPS (16.37%) > NPA+ (13.33%) > NPA− (9.78%). The homoaggregation of NPS and NPA− was observed in seawater. The transport of NPA− exhibited a ripening phenomenon (i.e., a decrease in the transport rate with time) due to the high attraction of NP with previously deposited NP, whereas monodispersed NPA+ presented a low Meff value because of the electrostatic attraction between NPA+ and negatively charged sand. Retention experiments showed that the majority of NPC, NPS and NPA+ accumulated in a monolayer on the sand surface, whereas NPA− accumulated in multiple layers. Suwannee River humic acid (SRHA) could remarkably improve the transportability of NPC, NPS, and NPA− by increasing steric repulsion. The strong attraction between NPA+ and the deposited NPA+ in the presence of SRHA triggered the weak ripening phenomenon. As seawater salinity decreased from 35 PSU to 3.5 PSU, the increase in electrostatic repulsion of NP-NP and NP-sand enhanced the transport of NPC, NPS, and NPA−, and the ripening of NPA− breakthrough curves disappeared. In deionized water, NPC, NPS, and NPA− achieved complete column breakthrough because the electrostatic repulsion between NP and sand intensified. However, the Meff values of NPA+ in 3.5 PSU seawater and deionized water presented limited increments of 15.49% and 23.67%, respectively. These results indicated that the fate of NP in sandy marine environments were strongly affected by NP surface functionalities, seawater salinity, and coexisting SRHA.
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25330. 题目: High-dispersion zero-valent iron particles stabilized by artificial humic acid for lead ion removal
文章编号: N19091409
期刊: Journal of Hazardous Materials
作者: Qing Du, Guixiang Li, Shuaishuai Zhang, Jingpeng Song, Ying zhao, Fan Yang
更新时间: 2019-09-14
摘要: Nano zero-valent iron (nZVI), as a high-efficiency adsorbent for heavy metals, often suffers being oxidized and assembling together due to small size and super reactivity, further decreasing its adsorption performance and limiting application ranges. Herein, we have designed a novel adsorbent with high-dispersion nZVI stabilized by as-prepared artificial humic acid (AHA-nZVI) derived from hydrothermal humification (HTH) technology. Introduction of artificial humic acid (A-HA) can effectively reduce the oxidation and agglomeration of nZVI, leading to superior kinetic removal efficiency of Pb2+ (> 99.2%) and huge Langmuir removal capacity of 649.0 mg/g. The combination of nZVI and A-HA (contained abundant functional groups, i.e. −OH and −COOH) via C–O-Fe bonding makes nZVI have good dispersion and oxidation resistance. Multiple interaction mechanisms including reduction reaction, complexation and co-precipitation between heavy metals and AHA-nZVI samples are realized. Overall, AHA-nZVI is a promising material for high-performance heavy metal contaminated water treatment.
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25331. 题目: Mechanism of Cr(VI) removal by magnetic greigite/biochar composites
文章编号: N19091408
期刊: Science of The Total Environment
作者: Xuedong Wang, Jin Xu, Jia Liu, Jun Liu, Fang Xia, Cuicui Wang, Randy A. Dahlgren, Wei Liu
更新时间: 2019-09-14
摘要: This study synthesized magnetic greigite/biochar composites (MGBs) by a solvothermal method and tested their ability to remove Cr(VI) from heavy metal-polluted wastewater. X-ray diffraction (XRD), Fourier transformed infrared spectrometry (FT-IR) and scanning electron microscopy (SEM) revealed that magnetic greigite (Fe3S4) flakes were aggregated and anchored to the biochar surface, resulting in more active sites than pristine biochar. Maximum Cr removal efficiency and capacity of MGB-30 (greigite/biochar = 30%) at an initial Cr(VI) concentration of 20 mg/L were 93% and 23.25 mg/g, respectively. A pseudo-first-order kinetic model was determined for the Cr(VI) removal process and the Cr(VI) removal rate constants were highly dependent on the mass ratios of Fe3S4 loaded on biochar, initial MGB and Cr(VI) concentrations and solution pH. X-ray photoelectron spectroscopy (XPS) and flame atomic absorption spectrometric (FAAS) analysis demonstrated that Cr(VI) was preferentially adsorbed on MGBs and subsequently reduced to Cr(III) by MGBs. Electron paramagnetic resonance (EPR) spectroscopy and iron redox transformations revealed that the Cr(VI) removal enhancement was attributed to efficient surface Fe(III)/Fe(II) cycling via electron transfer with the persistent free radicals (PFRs) of biochar. These novel findings provide new insights into the Fe(III)/Fe(II) cycle induced by biochar and the prospects of using magnetic greigite/biochar composites for remediation of Cr(VI)-rich wastewaters.
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25332. 题目: Biochar bound urea boosts plant growth and reduces nitrogen leaching
文章编号: N19091407
期刊: Science of The Total Environment
作者: Wei Shi, Yanyan Ju, Rongjun Bian, Lianqing Li, Stephen Joseph, David R.G. Mitchell, Paul Munroe, Sarasadat Taherymoosavi, Genxing Pan
更新时间: 2019-09-14
摘要: Over use of N fertilizers, most commonly as urea, had been seriously concerned as a major source of radiative N (Nr) for severe environment impacts through leaching, volatilization, and N2O emission from fertilized croplands. It had been well known that biochar could enhance N retention and use efficiency by crops in amended croplands. In this study, a granular biochar-mineral urea composite (Bio-MUC) was obtained by blending urea with green waste biochar supplemented with clay minerals of bentonite and sepiolite. This Bio-MUC material was firstly characterized by microscopic analyses with FTIR, SEM-EDS and STEM, subsequently tested for N leaching in water in column experiment and for N supply for maize in pot culture, compared to conventional urea fertilizer (UF). Microscopic analyses indicated binding of urea N to particle surfaces of biochar and clay minerals in the Bio-MUC composite. In the leaching experiment over 30 days, cumulative N release as NH4+-N and of dissolved organic carbon (DOC) was significantly smaller by >70% and by 8% from the Bio-MUC than from UF. In pot culture with maize growing for 50 days, total fresh shoot was enhanced by 14% but fresh root by 25% under Bio-MUC compared to UF. This study suggested that N in the Bio-MUC was shown slow releasing in water but maize growth promoting in soil, relative to conventional urea. Such effect could be related mainly to N retention by binding to biochar/mineral surfaces and partly by carbon bonds of urea to biochar in the Bio-MUC. Therefore, biochar from agro-wastes could be used for blending urea as combined organo/mineral urea to replace mineral urea so as to reduce N use and impacts on global Nr. Of course, how such biochar combined urea would impact N process in soil-plant systems deserve further field studies.
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25333. 题目: Effect of three artificial aging techniques on physicochemical properties and Pb adsorption capacities of different biochars
文章编号: N19091406
期刊: Science of The Total Environment
作者: Lianshuai Tan, Zhanghuai Ma, Kaiqi Yang, Qingliang Cui, Ke Wang, Tongtong Wang, Gao-Lin Wu, Jiyong Zheng
更新时间: 2019-09-14
摘要: Biochar is beneficial for soil amendment, but further research is still required on changes in its physicochemical properties during aging, especially in oxygen-containing functional groups and associated adsorption behaviors. Here, we used two different biochars, apple tree branch biochar and maize stalk biochar, and simulated the aging process by using freeze-thaw cycles, dry-wet cycles, and chemical oxidation methods. We investigated the changes in the physicochemical properties and Pb adsorption behavior of the biochars before and after aging treatments. The characterization results showed that the biochar surface structure changed after aging treatments. In general, the specific surface areas (SSAs) of the two biochars increased after chemical oxidation treatment but decreased after the other two treatments. The elemental content analyses indicated a decrease in the C content and increase in O content after artificial aging. In addition, the content of oxygen-containing functional groups in most biochars is increasing after treatment. The increase or decrease in SSA resulted in an increase or decrease in adsorption sites, respectively, thereby enhancing or reducing the adsorption capacity of the biochar. Furthermore, oxygen-containing functional groups enhanced the Pb adsorption capacity of biochar by complexation of free carboxyl and hydroxyl functional groups with Pb. Our research indicated that aging can lead to changes in the Pb adsorption capacity of biochar and that these changes vary depending on the type of aging and biochar. Our results will help to provide a better understanding of the changes in physicochemical properties and Pb adsorption capacity of biochar during the aging process in soil toward making full use of biochar for soil amendment.
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25334. 题目: Reservoir CO2 evasion flux and controlling factors of carbon species traced by δ13CDIC at different regulating phases of a hydro-power dam
文章编号: N19091405
期刊: Science of The Total Environment
作者: Imali Kaushalya Herath, Shengjun Wu, Maohua Ma, Ping Huang
更新时间: 2019-09-14
摘要: As the world largest hydropower reservoir, the Three Gorges Reservoir (TGR) significantly impacted on the carbon cycle since reservoirs are sources of carbon sink. This study was carried out to investigate the effects of damming on the carbon cycle. δ13CDIC and δ13CDOC were used to trace the origin of dissolved organic (DOC) and inorganic carbon (DIC). The estimated CO2 evasion flux in two regulating phases (discharge and recharge) with averages of 111 mg/m2 h and 264 mg/m2 h, respectively. At the basin scale, average CO2 flux was about 188 mg/m2 h and varies from −158 mg/m2 h to 1092 mg/m2 h. The highest average pCO2 (1294 ppmv) was observed during the discharge period, which was oversaturated than atmospheric equilibrium value; hence, the TGR act as a considerable sink of atmospheric carbon. The δ13CDIC varies from −8.95‰ to 0.00‰ with mean −1.87‰; these enrich isotope values indicated that metabolic process (photosynthesis and respiration) and the rapid kinetics of carbonate weathering by soil CO2 control the pCO2. The low pCO2 of reservoir water caused the rapid dissolution of CO2 from the atmosphere during the recharge period. The δ13CDOC varies between −30.64‰ to −23.05‰, which is similar to the values of C3 vegetation; thus, the source of DOC would be the degradation of soil organic matter. Overall, this study revealed the δ13CDIC signature coupled with soil CO2 dissolution and admixture of atmospherically equilibrated waters resulting in the sink of atmospheric CO2 of the reservoir and impoundment of the dam alters the carbon cycle and aquatic carbon budget in TGR. The findings of this study provide a global image on the contribution of reservoirs to the carbon cycle and aquatic carbon budget. Coupling with isotope signatures and elemental concentrations, investigation of the biogeochemical cycle of the carbon can be effectively traced.
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25335. 题目: Precursors for brominated haloacetic acids during chlorination and a new useful indicator for bromine substitution factor
文章编号: N19091404
期刊: Science of The Total Environment
作者: Lili Zheng, Hongjie Sun, Chouye Wu, Yibo Wang, Yuanyuan Zhang, Guangcai Ma, Hongjun Lin, Jianrong Chen, Huachang Hong
更新时间: 2019-09-14
摘要: Brominated haloacetic acids (HAAs) are much more cytotoxic and genotoxic than chlorinated one, yet little information is available for their organic precursors. In the present study, 8 water samples were collected in East China: 2 from lakes, 2 from rivers, 2 from reservoirs, a well and a mountain spring. Dissolved organic carbon (DOC), UV absorbance at 254 (UVA), specific UVA (SUVA) and chlorophyll a (Chl-a) were determined in raw water samples; formation of 9 HAA species as well as bromine substitution factor (BSF) were measured in chlorinated water samples. Results showed that water samples located in city generally contained higher levels of DOC (6.4–12.2 mg/L) and UVA (0.124–0.194/cm), while those in the country side, low DOC (2.4–5.9 mg/L) and UVA (0.061–0.109/cm) levels were observed. Negative relationship (p < 0.01) was found between SUVA values and Chl-a levels. Among 9 HAA species, 4 brominated HAA were detected. As for BAA and DBAA (i.e. Br-HAAs), their yields (μg/L) were significant related (p < 0.05) with DOC; In terms of BCAA and BDCAA (i.e. ClBr-HAAs), they were not only related with DOC, but also with UVA. These two results were quite different from DCAA and TCAA (Cl-HAAs), whose yields (μg/mg C) were only correlated with SUVA values, suggesting that precursors of Cl-HAA, Br-HAA and ClBr-HAA were different from each other, and their aromaticity/hydrophobicity may be in the order of Br-HAA < ClBr-HAA < Cl-HAA. Interrelationship between Br/DOC, SUVA and BSF revealed that BSF can be influenced by SUVA and Br/DOC, but in comparison, Br/UVA was the best indicator to describe BSF. This pattern is not only true in di-HAAs and tri-HAAs in this study, but also valid in other water samples and other species of disinfection by-product (e.g. trihalomethanes, dihaloacetonitriles, trihalonitromethanes).
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25336. 题目: Impact of bloom events on dissolved organic matter fluorophore signatures in Ohio waters
文章编号: N19091403
期刊: Science of The Total Environment
作者: Carissa Hipsher, Joel Barker, Allison MacKay
更新时间: 2019-09-14
摘要: Due to the increase in severe cyanobacterial blooms in drinking water sources and recreational waters across the globe, inexpensive and reliable methods of detecting oncoming blooms are needed. Cyanobacterial blooms can contribute substantially to the bulk chromophoric dissolved organic matter pool. Thus, the fluorescence signature of organic matter derived from these blooms may be an indicator of upcoming blooms. Water samples from five sites around Ohio were collected regularly between February and October 2017. A PARAFAC model was developed to determine if these protein-like fluorophores could be linked to bloom biomass and whether they were absent in dissolved organic matter from oligotrophic waters. One reference site at an oligotrophic reservoir was included to confirm the lack of protein-like fluorophores in the absence of a bloom event. We found that an increase in tryptophan-like and tyrosine-like fluorophores occurs before the increase in chlorophyll a levels, associated with bloom biomass, in some Ohio waters affected by cyanobacterial blooms; however, protein-like fluorophores are not correlated with levels of the cyanotoxin, microcystin. The excitation and emission wavelengths of these fluorophores (tryptophan-like: 239/341 nm, tyrosine-like: 248/306 nm) may be used to monitor impending blooms in waters heavily impacted by cyanobacteria but may not be applicable to waters receiving treated wastewater discharges.
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25337. 题目: Degradation of diclofenac in aqueous solution by ionizing radiation in the presence of humic acid
文章编号: N19091402
期刊: Separation and Purification Technology
作者: Run Zhuan, Jianlong Wang
更新时间: 2019-09-14
摘要: Diclofenac (DFC) is becoming a ubiquitous pollutant and pose a risk to ecosystem and human beings, which is usually used as a nonsteroidal anti-inflammatory drug for treating painful diseases. In this study, the degradation of DFC in aqueous solution by ionizing radiation was investigated in the presence of various concentrations of humic acid, due to its wide existence in water matrix as natural organic matter (NOM). The experimental results showed that the removal efficiency of DFC was 80.8% at 0.8 kGy absorbed dose and initial concentration of 30 mg/L. The DFC degradation by ionizing radiation could be described by pseudo first-order kinetics model. Humic acid had negative influence on the degradation efficiency of DFC, which decreased from 80.8% to 62.9% when humic acid concentration was 30 mg/L, mainly due to the competition between humic acid and DFC for OH radicals. Several intermediate products were identified by LC-MS analysis during DFC degradation process, and a possible degradation pathway of DFC by ionizing radiation was proposed.
25338. 题目: Soil organic matter is stabilized by organo-mineral associations through two key processes: The role of the carbon to nitrogen ratio
文章编号: N19091401
期刊: Geoderma
作者: Peter M. Kopittke, Ram C. Dalal, Carmen Hoeschen, Cui Li, Neal W. Menzies, Carsten W. Mueller
更新时间: 2019-09-14
摘要: The loss of organic matter (OM) from soil during long-term agricultural cropping results in a decrease in the inherent fertility of the soil as well as releasing greenhouse gases. Despite the importance of organo-mineral associations in the stabilization of OM within soils, much remains unknown about these organo-mineral associations. We used nano-scale secondary ion mass spectrometry (NanoSIMS) to investigate the incorporation and stabilization of 13C and 15N labelled residues of lucerne (Medicago sativa) and buffel grass (Cenchrus ciliaris) when incubated in a Vertisol from temperate Australia for up to 365 d. We show that newly-added OM forms organo-mineral associations through two mechanisms. Firstly, it was observed that the newly-added OM forms associations with the existing mineral-bound OM. However, this apparent stabilization of newly-added OM by associating with existing mineral-bound OM was not influenced by the C:N ratio of the plant residues, with the lucerne residues (C:N ratio of 11) being incorporated to a similar extent as the buffel grass (C:N ratio of 35). Secondly, we observed that N-rich microbial metabolites attached directly to mineral particle surfaces that did not contain existing OM patches, thereby creating new organo-mineral associations through which additional stabilization of OM would be possible. The information obtained in this study is valuable in understanding the stabilization of OM through organo-mineral associations, and raises the possibility of using cover crops or catch crops with narrow C:N ratios to allow for formation of new organo-mineral associations for increased stabilization of OM in soil.
25339. 题目: Hybrid ash/biochar biocomposites as soil amendments for the alleviation of cadmium accumulation by Oryza sativa L. in a contaminated paddy field
文章编号: N19091306
期刊: Chemosphere
作者: Sicong Lei, Yan Shi, Cong Xue, Junliang Wang, Lei Che, Yuping Qiu
更新时间: 2019-09-13
摘要: A novel ash/biochar (A/B) biocomposite composed of 90% biomass bottom ash from agroforestry biomass direct-fired power plants, 5% animal-derived biochar from carcass pyrolysis, and 5% bentonite as an adhesive was amended in cadmium (Cd)-polluted paddy soil to alleviate cadmium accumulation by Oryza sativa L. Ash increased the soil pH and contributed exogenous available silicon. Biochar with high Ca/P components played an important role in soil cadmium immobilization. A 1-year field experiment with consecutive rice growing seasons (early and late rice) was conducted in Xiangtan, China, to examine the effects of A/B amendment in Cd-contaminated paddy soil. The A/B biocomposite was amended into soil through one-time addition at three application rates (1, 5, and 10 kg/m2). When A/B amendment was ≥5 kg/m2, the soil pH increased from 4.11 to more than 6. The available silicon content in the soil even increased by 22.9 times. For early rice soil, the CaCl2-extractable Cd(II) and toxicity characteristic leaching procedure (TCLP)-extractable Cd(II) decreased by 77.9%–96.1% and 52.4%–70.7%, respectively. A/B remarkably reduced Cd accumulation in rice organs, and this observation was related to A/B treatment rates. Ash and biochar contributed to the inhibition of Cd accumulation in rice organs and Cd translocation from roots to stems. The Cd concentrations in brown rice decreased to 0.11 and 0.12 mg/kg in early and late rice, respectively, and these values were lower than the national food safety standard limit value of China (0.2 mg/kg).
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25340. 题目: Nitrogen addition promotes the transformation of heavy metal speciation from bioavailable to organic bound by increasing the turnover time of organic matter: An analysis on soil aggregate level
文章编号: N19091305
期刊: Environmental Pollution
作者: Renfei Li, Wenbing Tan, Guoan Wang, Xinyu Zhao, Qiuling Dang, Hanxia Yu, Beidou Xi
更新时间: 2019-09-13
摘要: Nitrogen (N) addition can change physicochemical properties and biogeochemical processes in soil, but whether or not these changes further affect the transport and transformation of heavy metal speciation is unknown. Here, a long-term (2004–2016) field experiment was conducted to assess the responses of different heavy metal speciation in three soil aggregate fractions to N additions in a temperate agroecosystem of North China. The organic matter turnover time was quantified based on changes in δ13C following the conversion from C3 (wheat) to C4 crop (corn). Averagely, N addition decreases and increases the heavy metal contents in bioavailable and organic bound fractions by 27.5% and 16.6%, respectively, suggesting N addition promotes the transformation of heavy metal speciation from bioavailable to organic bound, and such a promotion in a small aggregate fraction is more remarkable than that in a large aggregate fraction. The transformations of heavy metal speciation from bioavailable to organic bound in all soil aggregate fractions are largely dependent on the increments in the turnover time of organic matter. The increase in organic matter turnover time induced by N addition may inhibit the desorption of heavy metals from organic matter by prolonging the interaction time between heavy metals and organic matter and enhance the capacity of organic matter to adsorb heavy metals by increasing the humification degree and functional group. Our work can provide insights into the accumulation, migration, and transformation of heavy metals in soils in the context of increasing global soil N input from a microenvironmental perspective.
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