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14161. 题目: Lacustrine brGDGT response to microcosm and mesocosm incubations
文章编号: N18110308
期刊: Organic Geochemistry
作者: Pablo Martínez-Sosa, Jessica E. Tierney
更新时间: 2018-11-03
摘要: Branched dialkyl glycerol tetraethers (brGDGTs) are increasingly used as a paleotemperature proxy, yet the microbial producers of these compounds and the way they respond to environmental perturbations remain poorly understood. In this work, we used mesocosms to track the evolution of brGDGTs over several months, as well as an array of microcosms to study microbial brGDGT response to oxygen availability and carbon source. Overall our results confirm that brGDGTs are produced in the water column and respond to environmental perturbation. brGDGT concentrations increase in response to low oxygen, in agreement with empirical observations, but respond to added carbon only when ambient nutrients are low. Slow adjustment to temperature changes from the field to the laboratory appears to have influenced the relative methylation and isomerization of brGDGTs in the mesocosms. Overall our work is consistent with the inference that the producers are facultative aerobic heterotrophic organisms. Our results demonstrate that the use of micro- and mesocosms is a viable option to study brGDGTs in real time and help better understand this biomarker as a paleoproxy.

14162. 题目: Dissolved organic matter (DOM) in the open Mediterranean Sea. II: basin–wide distribution and drivers of fluorescent DOM
文章编号: N18110307
期刊: Progress in Oceanography
作者: Alba María Martínez–Pérez, Teresa S. Catalá, Mar Nieto–Cid, Jaime Otero, Marta Álvarez, Mikhail Emelianov, Isabel Reche, Xosé Antón Álvarez–Salgado, Javier Arístegui
更新时间: 2018-11-03
摘要: Fluorescent dissolved organic matter (FDOM) in the Mediterranean Sea was analysed by excitation–emission matrix (EEM) spectroscopy and parallel factor (PARAFAC) analysis during the cruise HOTMIX 2014. A 4–component model, including 3 humic–like and 1 protein–like compounds, was obtained. To decipher the environmental factors that dictate the distributions of these components, we run generalized additive models (GAMs) in the epipelagic layer and an optimum multiparametric (OMP) water masses analysis in the meso– and bathypelagic layers. In the epipelagic layer, apparent oxygen utilization (AOU) and temperature presented the most significant effects on the variability of the marine humic-like peak M fluorescence, suggesting that its distribution was controlled by the net community respiration of organic matter and photobleaching. On the contrary, the variability of the soil humic-like peak E and the protein–like peak T fluorescence was explained mainly by the prokaryotic heterotrophic abundance, which decreased eastwards. In the meso– and bathypelagic layers, water mass mixing and basin–scale mineralization processes explained more than 72% and 63% of the humic–like and protein–like fluorescence variability, respectively. When analysing the two basins separately, the OMP model offered a better explanation of the distribution of fluorescence in the eastern Mediterranean Sea, as expected from the reduced biological activity in this ultra–oligotrophic basin. Furthermore, while western Mediterranean deep waters display the usual trend in the global ocean (increase of humic–like fluorescence and decrease of protein–like fluorescence with higher AOU values), the eastern Mediterranean deep waters presented an opposite trend. Different initial fluorescence intensities of the water masses that mix in the eastern basin, with Adriatic and Aegean origins, seem to be behind this contrasting pattern. The analysis of the transect–scale mineralization processes corroborate this hypothesis, suggesting a production of humic–like and a consumption of protein–like fluorescence in parallel with water mass ageing. Remarkably, the transect–scale variability of the chromophoric dissolved organic matter (CDOM) absorbing at the excitation wavelength of the humic–like peak M indicates an unexpected loss with increasing AOU, which suggests that the consumption of the non–fluorescent fraction of CDOM absorbing at that wavelength exceeded the production of the fluorescent fraction observed here.

14163. 题目: Modification of natural zeolite and its application to advanced recovery of organic matter from an ultra-short-SRT activated sludge process effluent
文章编号: N18110306
期刊: Science of The Total Environment
作者: Guo-hua Liu, Yuanyuan Wang, Yuankai Zhang, Xianglong Xu, Lu Qi, Hongchen Wang
更新时间: 2018-11-03
摘要: Natural adsorbent was optimized from four natural adsorption materials (kaolin, bentonite, diatomite, and natural zeolite) through the comparison of their ability to recover organic matter from an ultra-short-sludge-retention-time (ultra-short-SRT) activated sludge process effluent. Natural zeolite was modified by the loading of three types of chemical coagulants (Fe2(SO4)3, Al2(SO4)3, and ZnSO4) and was used for the study of the advanced recovery of organic matter. The results of Brunauer–Emmett–Teller surface area (SBET) measurements, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses showed that natural zeolite was successfully modified, with decrease in the specific surface area of the modified zeolite (MZ), but some metal ions/metal oxides were loaded onto the surface of natural zeolite. Compared with chemical coagulant and natural zeolite, the organic recovery efficiency from the effluent of the MZs improved, and after the optimization process, the organic recovery efficiency of MZ4 (Zeolite:Fe2(SO4)3 = 4:1), MZ9 (Zeolite:Al2(SO4)3 = 4:1), and MZ13 (Zeolite:ZnSO4 = 2:1) reached 72.0%, 67.6%, and 61.2%, respectively. The MZs can allow a significant amount of recovery of soluble chemical oxygen demand (SCOD) from the effluent, with SCOD recovery efficiencies for MZ4, MZ9, and MZ13 of 44.8%, 44.3%, and 39.4%, respectively. The E4/E6, UV253/UV203, and SUVA analyses after the organic recovery experiments indicated that the generation potential of disinfecting byproducts or halogenated products was reduced in the treated effluent by the MZs. The mechanism can be considered in two ways: the coagulation effect of the loaded metal ions/metal oxides and the physical and chemical adsorption effect based on the hydrogen bond and ππ bond between the MZ and organic matter. This study facilitated the application of organic recovery from wastewater and the advanced treatment of effluent.
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14164. 题目: Soil ecosystem functions in a high-density olive orchard managed by different soil conservation practices
文章编号: N18110305
期刊: Applied Soil Ecology
作者: Nadia Vignozzi, Alessandro Elio Agnelli, Giorgio Brandi, Elena Gagnarli, Donatella Goggioli, Alessandra Lagomarsino, Sergio Pellegrini, Stefania Simoncini, Sauro Simoni, Giuseppe Valboa, Giovanni Caruso, Riccardo Gucci
更新时间: 2018-11-03
摘要: The long-term effects of two different soil management practices, natural grass cover (NC) and conservation tillage (CT), on soil functions (carbon sequestration, habitat for organisms, and water movement and retention) were determined in a high-density, mature olive orchard (Olea europaea L. cv. Frantoio) growing in a sandy loam soil (Typic Haploxeralf) in a Mediterranean environment. Ten years after the beginning of the different soil management, soil samples were collected at 0–10 and 10–20 cm depth and at two distances from the trunk, underneath the olive canopy (UC) and in the inter-row (IR). There were no differences in fruit yield, oil yield, and yield efficiency between the two soil management systems during the 2011–2013 period. CT negatively affected soil organic carbon pools (total and humified), but only at the IR position. The distance from the plant did not significantly influence soil structure and hydrological properties, while NC treatment increased water movement and retention. Tillage reduced the microarthropod abundance, in particular Collembola and eu-edaphic forms, which were the most sensitive groups to soil perturbation. We conclude that natural grass cover was more effective than conservation tillage in maintaining or improving elements of soil functionality.

14165. 题目: Predicting soil N supply and yield parameters in peat grasslands
文章编号: N18110304
期刊: Applied Soil Ecology
作者: Joachim G.C. Deru, Jaap Bloem, Ron de Goede, Nyncke Hoekstra, Harm Keidel, Henk Kloen, Andreas Nierop, Michiel Rutgers, Ton Schouten, Jan van den Akker, Lijbert Brussaard, Nick van Eekeren
更新时间: 2018-11-03
摘要: Considerable nitrogen (N) mineralization occurs in drained peat soils in use for dairy grassland, due to aerobic decomposition of soil organic matter (SOM). N losses may be limited by matching grass N uptake with N mineralization and by adapting on-farm fertilization schemes to soil N supply (SNS) and apparent N recovery (ANR). Previous attempts to predict SNS of peat grasslands from soil parameters have been unsuccessful, partly due to high variation in SNS between sites and years. In this paper, we present field data from twenty dairy grasslands on drained peat (29–65% SOM; Terric Histosols). Grass yield parameters (e.g. SNS and ANR) were compared with a comprehensive data set of soil biotic and abiotic properties measured at the start of the growing season, and with N mineralization calculated from this data. SNS ranged between 171 and 377 kg N ha−1 (mean: 264 kg N ha−1) during the growing season. Soil N mineralization estimated by laboratory incubation and by foodweb-based production ecological calculations gave similar mean values with slightly higher coefficients of variation, but correlations with SNS were not significant. Regression analysis with soil properties showed a positive correlation between SNS and soil Ca:Mg ratio and a negative correlation between fertilized grass yield and soil C:SOM ratio. No significant models were found for ANR. Based on our data and on literature, we conclude that these parameters indicate linkages between grass yield and soil physical-hydrological properties such as soil structure and water availability. In particular, the C:SOM ratio in these soils with high organic matter content may be an indicator of water repellency, and our results suggest that grass growth was limited by drought more than by nutrient availability.

14166. 题目: Out of sight: Profiling soil characteristics, nutrients and bacterial communities affected by organic amendments down to one meter in a long-term maize experiment
文章编号: N18110303
期刊: Applied Soil Ecology
作者: Taru Sandén, Laura Zavattaro, Heide Spiegel, Carlo Grignani, Hans Sandén, Andreas Baumgarten, Marja Tiirola, Anu Mikkonen
更新时间: 2018-11-03
摘要: Common soil characteristics, nutrients and microbial activity at deeper soil depths are topics seldom covered in agricultural studies. Biogeochemical cycles in deep soils are not yet fully understood. This study investigates the effect of different mineral and organic fertilisation on soil organic matter dynamics, nutrients and bacterial community composition in the first meter of the soil profiles in the long-term maize cropping system experiment Tetto Frati, near the Po River in northern Italy. The following treatments have been applied since 1992: 1) crop residue removal (CRR), 2) crop residue incorporation (CRI), 3) crop residue removal with bovine slurry fertilisation (SLU), 4) crop residue removal with farmyard manure fertilisation (FYM). A total of 250 kg N ha−1 were applied annually as mineral fertiliser in the first two and as organic fertilizer in the latter two treatments. Soil organic carbon (SOC) was significantly higher in the treatments with organic amendments (CRI, SLU and FYM) compared to CRR in 0–25 cm (11.1, 11.6, 14.7 vs. 9.8 g kg−1, respectively), but not in the deeper soil. At 75–100 cm soil depth, SLU and FYM had the highest potential N mineralisation. Bacterial diversity decreased down the soil profile much less than microbial biomass. Incorporation of crop residues alone showed no positive effects on either biomass or diversity, whereas fertilisation by FYM instead of mineral fertilizer did. Bacterial community composition showed depth-related shifts: Proteobacteria and Actinobacteria dominated the topsoil, whereas Chloroflexi, Nitrospira and Thermotogae were relatively more abundant deeper in the soil profile. Although the main factor determining soil bacterial community composition in the entire dataset was soil depth, both the size and diversity of bacterial community, as well as several discriminating taxa, were affected by organic N fertilisation down to 1 m depth. This calls for continued efforts to study the deeper soil depths in the numerous long-term field experiments, where mostly topsoils are currently studied in detail.

14167. 题目: Identification of the alteration of riparian wetland on soil properties, enzyme activities and microbial communities following extreme flooding
文章编号: N18110302
期刊: Geoderma
作者: Yang Ou, Alain N. Rousseau, Lixia Wang, Baixing Yan, Thiago Gumiere, Hui Zhu
更新时间: 2018-11-03
摘要: In China, most riparian wetlands have undergone degradation and shrinkage, due to severe droughts or low hydrological connectivity. There are considerable studies focusing on the impact of water level on wetland vegetation; however, changes in the soil components, such as the microbial community, of wetlands following flooding remains unclear. Here, we verified the effects of an extreme flooding event on the soil physicochemical conditions, enzyme activities and soil microbial composition. Overall, we observed that the flooding event impacted the soil properties and modified the enzyme activities. Also, the flooding affected more the biomass than the composition of the soil microbial community. We observed that after the flooding event, manganese (Mn) replaced total nitrogen (TN) as one of the major governing factors of soil enzyme activities. Soil organic carbon (SOC), and pH were also correlated with soil enzyme activities before and after the flooding event. Soil conductivity (EC), C/N ratio, and iron (Fe) contents had a large influence on microbial communities. Nevertheless, the soil C/N ratio was the dominant governing factor of the microbial structure. Therefore, edaphic factors were remarkably related to microbial organisms as flooding was deemed a key driving factor to the linkage between them. The antecedent long-term drought provoked by human disturbance, and subsequent flooding (i.e., re-inundating) may thus damage the soil dynamics of riparian wetlands, and hence, altering the carbon storage capacity. The results of this study suggest that rehabilitating hydrological connectivity and promoting primary succession of vegetation could become effective practices for improving the soil ecosystem of riparian wetlands.

14168. 题目: Importance of CO2 production in subsoil layers of drained tropical peatland under mature oil palm plantation
文章编号: N18110301
期刊: Soil and Tillage Research
作者: Setiari Marwanto, Supiandi Sabiham, Shinya Funakawa
更新时间: 2018-11-03
摘要: Expansion of oil palm (Elaeis guineensis Jacq.) plantations in tropical peatlands is always followed by a lowering groundwater level, which exposes peat to oxidic condition and releases large amounts of carbon dioxide (CO2) to atmosphere. This study is concerned with decomposition of organic matter in the soil profile of tropical peatland under oil palm plantation. For 2 years, CO2 fluxes were measured from the soil surface (CO2-efflux) and from the surface where peat was removed to the depths of 10, 30 and 50 cm (CO2 efflux potential/CO2-EP). CO2-EP is a potential estimation of organic matter decomposition from subsoil. Groundwater level, soil moisture and soil temperature were measured as soil environmental factors. The annual CO2 efflux was 139 mg m–2 h–1 while CO2-EP increased with depth which were 1032, 1209, 2304 mg m–2 h–1 from 10, 30, 50 cm depths, respectively. CO2 efflux did not significantly correlated with soil environmental factors. CO2-EP had a significant negative correlation with groundwater level and soil moisture at depths of 30 cm and 50 cm. There are significant correlations among CO2 released from 0, 10, 30, and 50 cm depths. These results indicated that the formation of CO2 in the deeper peat contributes greatly to the emission of CO2, and that keeping the groundwater level at a high level will greatly contribute to the suppression of CO2 emissions from peatland. The subsoil of cultivated peatland is considered to be vulnerable, and its exploitation should be avoided.

14169. 题目: Oxygen Consumption and Organic Matter Remineralization in Two Subtropical, Eutrophic Coastal Embayments
文章编号: N18110215
期刊: Environmental Science & Technology
作者: Hongjie Wang, Xinping Hu, Michael S. Wetz, Kenneth C. Hayes
更新时间: 2018-11-02
摘要: There is a strong need to understand sources of organic matter in coastal lagoons because these systems often have long water residence times, are susceptible to eutrophication, and display symptoms such as low-oxygen conditions. We found that integrated dissolved oxygen (DO) consumption in the water column accounted for 67–73% of total DO consumption in two eutrophic coastal lagoons (Baffin Bay and Oso Bay) in the northwestern Gulf of Mexico. The δ13C of particulate organic carbon (δ13CPOC) showed temporal variations that corresponded with hydrological condition changes in Baffin Bay but fewer temporal changes in Oso Bay, whereas the lower δ15NPON values in Baffin Bay indicated more agricultural influence than in Oso Bay, where urban sewage influences dominated. Based on closed-system incubation experiments, water-column respiration in Baffin Bay was driven by the respiration of a combination of phytoplankton, carbon from near-shore and benthic macrophytes, and other allochthonous organic carbon sources depending on hydrological conditions. However, respiration of algal carbon dominated DO consumption in Baffin Bay sediments. In comparison, Oso Bay water-column respiration was largely attributed to the degradation of phytoplankton, the growth of which was sustained by nutrient discharge from wastewater treatment plants in the watershed. In contrast to the water column, seagrass and saltmarsh carbon appeared to be the primary organic carbon source that drove DO consumption in Oso Bay sediments. These observations highlight the complexity of organic carbon sources that contribute to DO consumption in estuaries affected by human activities, especially in systems with long water residence times that can retain both organic matter and nutrients for extended periods of time.
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14170. 题目: Mechanisms of the Removal of U(VI) from Aqueous Solution Using Biochar: A Combined Spectroscopic and Modeling Approach
文章编号: N18110214
期刊: Environmental Science & Technology
作者: Md. Samrat Alam, Drew Gorman-Lewis, Ning Chen, Salman Safari, Kitae Baek, Kurt O. Konhauser, Daniel S. Alessi
更新时间: 2018-11-02
摘要: Biochar has been touted as a promising sorbent for the removal of inorganic contaminants, such as uranium (U), from water. However, the molecular-scale mechanisms of aqueous U(VI) species adsorption to biochar remain poorly understood. In this study, two approaches, grounded in equilibrium thermodynamics, were employed to investigate the U(VI) adsorption mechanisms: (1) batch U(VI) adsorption experiments coupled to surface complexation modeling (SCM) and (2) isothermal titration calorimetry (ITC), supported by synchrotron-based X-ray absorption spectroscopy (XAS) analyses. The biochars tested have considerable proton buffering capacity and most strongly adsorb U(VI) between approximately pH 4 and 6. FT-IR and XPS studies, along with XAS analyses, show that U(VI) adsorption occurs primarily at the proton-active carboxyl (−COOH) and phenolic hydroxyl (−OH) functional groups on the biochar surface. The SCM approach is able to predict U(VI) adsorption behavior across a wide range of pH and at varying initial U(VI) and biochar concentrations, and U adsorption is strongly influenced by aqueous U(VI) speciation. Supporting ITC measurements indicate that the calculated enthalpies of protonation reactions of the studied biochar, as well as the adsorption of U(VI), are consistent with anionic oxygen ligands and are indicative of both inner- and outer-sphere complexation. Our results provide new insights into the modes of U(VI) adsorption by biochar and more generally improve our understanding of its potential to remove radionuclides from contaminated waters.
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14171. 题目: Changing depositional environment and factors controlling the growth of mudflat in a tropical estuary, west coast of India
文章编号: N18110213
期刊: Environmental Earth Sciences
作者: G. N. Nayak, S. P. Volvoikar, T. Hoskatta
更新时间: 2018-11-02
摘要: Mudflats and associated mangroves are most important ecosystems of tropical coastal regions. Mangroves play a very important role in maintaining the environmental balance; thus in addition to mangrove reforestation and restoration, afforestation has also been practiced. We studied distribution of sediment components (sand, silt, clay) organic carbon (OC), heavy metals (Fe, Mn, Cu, Zn, Cr and Co) and pH in six cores collected from one of the largest mudflats of Mandovi estuary, west coast of India. The temporal distribution patterns of these proxies suggested that past changes in tidal energy conditions, fresh water inflow and anthropogenic activities over the last few decades, together helped in development of a middle tidal flat in this estuary. In cores collected from the mangroves, trapping and deposition of finer particles and organic matter were enhanced by a complex aerial mangrove root system in recent years. Mangroves were, therefore, suggested to enhance the buildup of mudflats in Mandovi estuary. Cores collected from mudflats also exhibited higher deposition of finer particles and organic matter (except MF2) in recent years, suggesting maturity and greater stability of the entire mudflat in recent years. Middle tidal flats (mudflats) of Mandovi estuary may, therefore, prove to be suitable substrates for mangrove proliferation in the near future. Finer sediments deposited mainly from mining activities in recent years exhibited lower pH and higher metal content. Organisms dwelling in these recently deposited sediments are, therefore, at higher risk of bioaccumulation and metal toxicity.

14172. 题目: Influence of pyrolysis temperature on characteristics and environmental risk of heavy metals in pyrolyzed biochar made from hydrothermally treated sewage sludge
文章编号: N18110212
期刊: Chemosphere
作者: Xingdong Wang, Qiaoqiao Chi, Xuejiao Liu, Yin Wang
更新时间: 2018-11-02
摘要: A novel approach was used to prepare sewage sludge (SS)-derived biochar via coupling of hydrothermal pretreatment with pyrolysis (HTP) process at 300–700 °C. The influence of the pyrolysis temperature on the characteristics and environmental risk of heavy metals (HMs) in biochar derived from SS were investigated. The HTP process at higher pyrolysis temperature (≥500 °C) resulting in a higher quality of SS-derived biochar and in HMs of lower toxicity and environmental risk, compared with direct SS pyrolysis. Surface characterization and micromorphology analysis indicate that the N2 adsorption capacity and BET surface area in biochar (SRC220-500) obtained from hydrothermally treated SS at 220 °C (SR220) pyrolysis at 500 °C, significantly increased the BET surface area and achieved its maximum value (47.04 m2/g). Moreover, the HTP process can promote the HMs in SS be transformed from bioavailable fractions to more stable fractions. This increases with the pyrolysis temperature, resulting in a remarkable reduction in the potential environmental risk of HMs from the biochar obtained from the HTP process.
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14173. 题目: From micro to macro-contaminants: The impact of low-energy titanium dioxide photocatalysis followed by filtration on the mitigation of drinking water organics
文章编号: N18110211
期刊: Chemosphere
作者: Brooke K. Mayer, Carlan Johnson, Yu Yang, Nicole Wellenstein, Emily Maher, Patrick J. McNamara
更新时间: 2018-11-02
摘要: This study evaluated strategies targeting macro- and micro-organic contaminant mitigation using low-energy titanium dioxide photocatalysis. Energy inputs of 1, 2, and 5 kWh m−3 resulted in incomplete oxidation of macro-organic natural organic matter, signified by greater reductions of UV254 and specific ultraviolet UV absorbance (SUVA) in comparison to dissolved organic carbon (DOC). The rate of UV254 removal was 3 orders of magnitude greater than the rate of DOC degradation. Incomplete oxidation improved operation of downstream filtration processes. Photocatalysis at 2 kWh m−3 increased the bed life of downstream granular activated carbon (GAC) filter by 340% relative to direct filtration pretreatment. Likewise, photocatalysis operated ahead of microfiltration decreased fouling, resulting in longer filter run times. Using 2 kWh m−3 photocatalysis increased filter run time by 36 times in comparison to direct filtration. Furthermore, levels of DOC and UV254 in the membrane permeate improved (with no change in removal across the membrane) using low-energy photocatalysis pretreatments. While high-energy UV inputs provided high levels of removal of the estrogenic micro-organics estrone (E1), 17β-estradiol (E2), estriol (E3), and 17α-ethynlestradiol (EE2), low-energy photocatalysis did not enhance removal of estrogens beyond levels achieved by photolysis alone. In the cases of E1 and E3, the addition of TiO2 as a photocatalyst reduced degradation rates of estrogens compared to UV photolysis. Overall, process electrical energy per order magnitude reductions (EEOs) greatly improved using photocatalysis, versus photolysis, for the macro-organics DOC, UV254, and SUVA; however, energy required for removal of estrogens was similar between photolysis and photocatalysis.
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14174. 题目: Effect of polybrominated diphenyl ethers on the formation of disinfection byproducts in the water system
文章编号: N18110210
期刊: Chemosphere
作者: Huihui Wang, Hui Ma, Min Zhang, Tingting Du, Rongjie Hao, Mengmeng Liu, Yao Li
更新时间: 2018-11-02
摘要: Disinfection byproducts (DBPs) can be formed from many different kinds of carbon- and nitrogen-based organic materials. This study investigated DBP formation in the presence of two types of polybrominated diphenyl ethers (PBDEs), 2,2′,4,4′-tetrabromodiphenyl ether (BDE 47) and 2,2′,3,3′,4,4′,5,5′,6,6′-decabromodiphenyl ether (BDE 209). The effects of PBDEs on the formation of DBPs upon the chlorination (or chloramination) of Suwannee River humic acid (SRHA) were also evaluated. Results indicated that the chlorination of BDE 47 and BDE 209 resulted in the formation of DBPs, with 1,1,1-trichloro-2-propanone (1,1,1-TCP) being the major DBP type formed. When PBDEs were present in the SRHA solution, a lower amount of CHCl3 was formed, and more 1,1,1-TCP was produced. However, the effects of PBDEs on the formation of DBPs in the real surface water were insignificant because of the complicated water chemistry.

14175. 题目: Bioaccumulation and trophic transfer of total mercury in the subtropical Olifants River Basin, South Africa
文章编号: N18110209
期刊: Chemosphere
作者: Vera Verhaert, Johannes Teuchies, Wynand Vlok, Victor Wepener, Abraham Addo-Bediako, Antoinette Jooste, Ronny Blust, Lieven Bervoets
更新时间: 2018-11-02
摘要: The present study describes total mercury (THg) levels in surface water, sediment and biota from the Olifants River Basin (ORB) (South Africa) and investigates the trophic transfer of THg by means of trophic magnification factors (TMFs) in the subtropical ORB food web.Although levels in surface water, sediment and invertebrates were low, elevated levels of THg were measured in fish species of higher trophic levels (0.10–6.1 μg/g dw). This finding supports the biomagnificative character of mercury. THg concentrations in fish from the present study were find to be higher than most values reported in fish from other African aquatic ecosystems and comparable or lower compared to more industrialized regions. Fish length, trophic level, sediment THg levels and TOC in sediment were determining factors for THg levels in fish tissue. Concentrations were found to be higher in larger (and older) fish. Mercury has a high affinity for organic matter and will bind with the TOC in sediment, thus reducing the bioavailability of THg for aquatic biota which is reflected in the significant negative correlation between THg and TOC in sediment. A significant positive relationship between relative trophic level and THg concentrations was observed and also TMFs indicate biomagnification in the ORB food web. However, the trend of lower TMFs in tropical areas compared to temperate and arctic regions was not supported by the results. The consumption of fish from higher trophic levels at the average South African consumption rate is expected to pose a significant health risk.
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14176. 题目: Removal of disinfection byproduct precursors and reduction in additive toxicity of chlorinated and chloraminated waters by ozonation and up-flow biological activated carbon process
文章编号: N18110208
期刊: Chemosphere
作者: Han Chen, Tao Lin, Wei Chen, Hui Tao, Hang Xu
更新时间: 2018-11-02
摘要: The variations of disinfection byproduct (DBP) precursors and DBPs-associated toxic potencies were evaluated by ozonation, followed by a up-flow biological activated carbon (O3/UBAC) filter treating two reconstituted water samples, featuring either high bromide (105.3 μg/L) or dissolved organic nitrogen (0.73 mg N/L) concentration, respectively. Ozonation contributed to ∼20% decrease in dissolved organic carbon (DOC) concentration at a dosage of 0.7 mg of O3/mg of DOC, but no further reduction in DOC level was observed with an increased dose of 1.0 mg of O3/mg of DOC. When chlorine or preformed monochloramine was used as a disinfectant, UBAC process led to ∼40% reduction in the sum of detected DBP formation potential (FP) due to the removal of precursors at a feasible empty bed contact time of 15 min. The integrated effect of ozonation and UBAC biofiltration decreased the sum of DBP FP by ∼50% including halonitromethanes (THNMs), N-nitrosamines (NAs), and bromate, which increased in the effluent of ozonation. Chloramination produced less DBPs by weight as well as DBPs-associated additive toxic potencies than chlorination. The reduction in additive toxic potencies was generally lower than the removal efficiency of DBP FP after chlor(am)ination of treated waters by O3/UBAC, indicating that the removal of DBPs-associated additive toxic potencies should be focused to better understand on the residual risk to public health in controlling DBP precursors.
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14177. 题目: Identification of textile wastewater in water bodies by fluorescence excitation emission matrix-parallel factor analysis and high-performance size exclusion chromatography
文章编号: N18110207
期刊: Chemosphere
作者: Bo Liu, Jing Wu, Cheng Cheng, Jiukai Tang, Muhammad Farooq Saleem Khan, Jian Shen
更新时间: 2018-11-02
摘要: Identifying the causes of water body pollution is critical because of the serious water contamination in developing countries. The textile industry is a major contributor to severe water pollution due to its high discharge of wastewater with high concentrations of organic and inorganic pollutants. In this study, fluorescence excitation emission matrix–parallel factor (EEM-PARAFAC) analysis was applied to characterize textile industry wastewater and trace its presence in water bodies. The EEM spectra of textile wastewater samples collected from 12 wastewater treatment plants (WWTPs) revealed two characteristic peaks: Peak T1 (tryptophan-like region) and Peak B (tyrosine-like region). Two protein-like components (C1 and C2) were identified in the textile wastewater by PARAFAC analysis. The components identified from different textile WWTPs were considered identical (similarity >0.95). C1 and C2 were not sensitive to changes in pH, ionic strength, or low humic acid concentration (TOC < 4 mg/L). Therefore, C1 combined with C2 was proposed as a source-specific indicator of textile wastewater, which was further demonstrated by conducting high-performance size exclusion chromatography analysis. These results suggested that EEM-PARAFAC analysis is a reliable means of identifying textile wastewater pollution in water bodies and may also enable the identification of other industrial wastewater.
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14178. 题目: An overview of the uses of high performance size exclusion chromatography (HPSEC) in the characterization of natural organic matter (NOM) in potable water, and ion-exchange applications
文章编号: N18110206
期刊: Chemosphere
作者: Kenneth Brezinski, Beata Gorczyca
更新时间: 2018-11-02
摘要: Natural organic matter (NOM) constitutes the terrestrial and aquatic sources of organic plant like material found in water bodies. As of recently, an ever-increasing amount of effort is being put towards developing better ways of unraveling the heterogeneous nature of NOM. This is important as NOM is responsible for a wide variety of both direct and indirect effects: ranging from aesthetic concerns related to taste and odor, to issues related to disinfection by-product formation and metal mobility. A better understanding of NOM can also provide a better appreciation for treatment design; lending a further understanding of potable water treatment impacts on specific fractions and constituents of NOM. The use of high performance size-exclusion chromatography has shown a growing promise in its various applications for NOM characterization, through the ability to partition ultraviolet absorbing moieties into ill-defined groups of humic acids, hydrolysates of humics, and low molecular weight acids. HPSEC also has the ability of simultaneously measuring absorbance in the UV–visible range (200–350 nm); further providing a spectroscopic fingerprint that is simply unavailable using surrogate measurements of NOM, such as total organic carbon (TOC), ultraviolet absorbance at 254 nm (UV254), excitation-emission matrices (EEM), and specific ultraviolet absorbance at 254 nm (SUVA254). This review mainly focuses on the use of HPSEC in the characterization of NOM in a potable water setting, with an additional focus on strong-base ion-exchangers specifically targeted for NOM constituents.
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14179. 题目: Pretreatment of landfill leachate in near-neutral pH condition by persulfate activated Fe-C micro-electrolysis system
文章编号: N18110205
期刊: Chemosphere
作者: Weixuan Zhang, Xiaoming Li, Qi Yang, Dongbo Wang, You Wu, Xiaofei Zhu, Jing Wei, Yu Liu, Lihua Hou, Chongyu Chen
更新时间: 2018-11-02
摘要: In this study, a novel persulfate combined with iron-carbon microelectrolysis (PS-ICME) system was explored to pretreat the landfill leachate. In the static batch experiments, response surface methodology (RSM) was used to determine the relationship between three independent variables (pH, the ratio of iron to carbon (Fe-C ratio), persulfate dosage) and response values (Chemical oxygen demand (COD) removal efficiency). Experimental results showed that the COD removal efficiency reached to 62.91% under the optimal conditions: initial pH 7, Fe-C ratio 3, and persulfate dosage 85 mM. The dissolved organic matter (DOM) in landfill leachate was characterized by three-dimensional excitation-emission matrix spectroscopy (3D-EEMs). Combined with electron spin resonance (ESR) spectrum investigation, the enhanced mechanism for landfill leachate pretreated by PS-ICE in near-neutral pH was elucidated. In the column continuous flow experiment, it had been confirmed that dissolved oxygen plays an important role in the PS-ICME system. Based on the above conclusions, PS-ICME system has a satisfactory performance on pretreatment of landfill leachate.
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14180. 题目: Development of rare earth element doped magnetic biochars with enhanced phosphate adsorption performance
文章编号: N18110204
期刊: Colloids and Surfaces A: Physicochemical and Engineering Aspects
作者: Li Wang, Jingyi Wang, Chi He, Wei Lyu, Wenlong Zhang, Wei Yan, Liu Yang
更新时间: 2018-11-02
摘要: To improve the biochar’s adsorption performance towards phosphate as well as to endow the biochar with magnetic property, novel rare earth element doped magnetic biochars, Ce/Fe3O4-BC and La/Fe3O4-BC, were prepared by separately co-precipitating cerium (Ce) and lanthanum (La) with FeCl3, FeCl2 and biochar. For comparison, Fe3O4-BC without doping Ce or La was also synthesized. The characterization results indicated that Ce and La ions were successfully doped into the magnetite. The La/Fe3O4-BC had higher magnetic saturation and point of zero charge than Ce/Fe3O4-BC. A series of batch experiment results demonstrated that the phosphate adsorption capacity of biochar has been greatly improved after Ce or La doping, especially La. The phosphate adsorption capacity of La/Fe3O4-BC was 20.5 mg/g at pH 6.5, which was 1.6 and 2.9 times than that of Ce/Fe3O4-BC and Fe3O4-BC, respectively. The adsorption kinetics and isotherms of phosphate onto La/Fe3O4-BC and Ce/Fe3O4-BC were best fitted by the pseudo-second order and Freundich model, respectively, indicating that the adsorption process was a multilayer process and controlled by chemical reaction. The combined results of batch experiments and physiochemical analyses revealed that the possible mechanisms were the formation of inner-sphere complex at neutral conditions and electrostatic attraction between positively charged adsorption sites and phosphate under acid conditions. The enhanced phosphate adsorption performance and endowed magnetic property indicated La/Fe3O4-BC could be used as a promising adsorbent in phosphate removal.
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