论文检索

主页 | 软件工具 | 课题库 | 公众号
:



总访问量:1733871

总访客量:86891

关键词:
Organic Matter |
DOM |
POM |
Soil OM |
Sediment OM |
Organic Carbon |
Organic Nitrogen |
Biomarker |
Humic Substances |
Fulvic Substances |
Humins |
Biochar |
Black Carbon |
GDGT |
Lignin |
Free Radical |
...
最新文章  | 
昨日文章 | 
前日文章
期刊:
Agriculture, Ecosystems & Environment |
Agricultural Water Management |
Applied Geochemistry |
Applied Soil Ecology |
Aquatic Geochemistry |
Atmospheric Research |
Biogeochemistry |
Biogeosciences |
Biology and Fertility of Soils |
Bioresource Technology |
CATENA |
Chemical Engineering Journal |
Chemical Geology |
Chemosphere |
CLEAN - Soil, Air, Water |
Colloids and Surfaces A: Physicochemical and Engineering Aspects |
Deep Sea Research Part II: Topical Studies in Oceanography |
Earth-Science Reviews |
Ecological Engineering |
Ecology Letters |
Ecology |
Ecotoxicology and Environmental Safety |
Environment International |
Environmental Earth Sciences |
Environmental Geochemistry and Health |
Environmental Monitoring and Assessment |
Environmental Pollution |
Environmental Research |
Environmental Science & Technology |
Environmental Science and Pollution Research |
Environmental Science: Processes Impacts |
Environmental Science: Water Research & Technology |
Environmental Toxicology and Chemistry |
Estuarine, Coastal and Shelf Science |
European Journal of Soil Science |
Forest Ecology and Management |
Geochimica et Cosmochimica Acta |
Geoderma |
Geophysical Research Letters |
Global Change Biology |
Global Biogeochemical Cycles |
Groundwater |
Harmful Algae |
International Journal of Coal Geology |
Journal of Environmental Chemical Engineering |
Journal of Environmental Management |
Journal of Environmental Sciences |
Journal of Geophysical Research: Biogeosciences |
Journal of Geophysical Research: Oceans |
Journal of Hazardous Materials |
Journal of Membrane Science |
Journal of Soils and Sediments |
Land Degradation & Development |
Limnology and Oceanography |
Marine Chemistry |
Marine Pollution Bulletin |
Nature Communications |
Nature Geoscience |
Ocean Science Journal |
Oikos |
Organic Geochemistry |
Palaeogeography, Palaeoclimatology, Palaeoecology |
Plant and Soil |
Progress in Oceanography |
Quaternary International |
Science of The Total Environment |
Sedimentary Geology |
Separation and Purification Technology |
Soil and Tillage Research |
Soil Biology and Biochemistry |
Waste Management |
Water Research |
Water, Air, & Soil Pollution |
Wetlands |
...

所有论文

21701. 题目: Fouling resistant functional blend membrane for removal of organic matter and heavy metal ions
文章编号: N18112910
期刊: Journal of Environmental Management
作者: C. Lavanya, R. Geetha Balakrishna, Khantong Soontarapa, Mahesh S. Padaki
更新时间: 2018-11-29
摘要: This study investigates the removal of heavy metal ions and humic acid using Cellulose acetate (CA) and Poly (methyl vinyl ether-alt-maleic acid) (PMVEMA) blend membranes. Antifouling properties of blend membranes were also investigated. Flat sheet membranes were prepared by phase inversion technique using different concentrations of CA and PMVEMA. The prepared membranes were characterized and their performance was evaluated by measuring pure water flux, water uptake capacity and humic acid removal. Rejection of humic acid (HA) was observed to be around 97% for all the blend membranes because of electrostatic interactions between the functional groups of HA and blends. The fouling characteristics of the membranes was assessed using HA as a foulant and the antifouling capacity of blend membranes was observed to be greater with a flux recovery ratio of almost 95% when compared to bare CA, commercial CA (TechInc) and other reported CA blends used for HA rejection. Also, the blend membranes were very effective in removing heavy metal ions (Pb2+, Cd2+ and Cr+6) and humic acid simultaneously. Overall, the PMVEMA modified CA membranes can open up new possibilities in enhancing the hydrophilicity, permeability and antifouling properties.
图文摘要:

21702. 题目: Lipid biomarker distributions in Oligocene and Miocene sediments from the Ross Sea region, Antarctica: Implications for use of biomarker proxies in glacially influenced settings
文章编号: N18112909
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Bella Duncan, Robert McKay, James Bendle, Timothy Naish, Gordon N. Inglis, Heiko Moossen, Richard Levy, G. Todd Ventura, Adam Lewis, Beth Chamberlain, Carrie Walker
更新时间: 2018-11-29
摘要: Biomarker-based climate proxies enable climate and environmental reconstructions for regions where other paleoclimatic approaches are unsuitable. The Antarctic Cenozoic record consists of widely varying lithologies, deposited in rapidly changing depositional settings, with large lateral variations. Previous sedimentological and microfossil studies indicate that the incorporation of reworked older material frequently occurs in these sediments, highlighting the need for an assessment of biomarker distribution across a range of depositional settings and ages to assess the role reworking may have on biomarker-based reconstructions. Here, we compare sedimentary facies with the distribution of n-alkanes and hopanoids within a terrestrial outcrop, two glaciomarine cores and a deep sea core, spanning the Late Oligocene to Miocene in the Ross Sea. Comparisons are also made with n-alkane distributions in Eocene glacial erratics and Mesozoic Beacon Supergroup sediments, which are both potential sources of reworked material. The dominant n-alkane chain length shifts from n-C29 to n-C27 between the Late Eocene and the Oligocene. This shift is likely due to changing plant community composition and the plastic response of n-alkanes to climate cooling. Samples from glaciofluvial environments onshore, and subglacial and ice-proximal environments offshore are more likely to display reworked n-alkane distributions, whereas, samples from lower-energy, lacustrine and ice-distal marine environments predominantly yield immature/contemporaneous n-alkanes. These findings emphasise that careful comparisons with sedimentological and paleontological indicators are essential when applying and interpreting n-alkane-based and other biomarker-based proxies in glacially-influenced settings.

21703. 题目: Frequent euxinia in southern Neo-Tethys Ocean prior to the end-Permian biocrisis: Evidence from the Spiti region, India
文章编号: N18112908
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Alan Stebbins, Jeremy Williams, Michael Brookfield, Steven W. Nye, Robyn Hannigan
更新时间: 2018-11-29
摘要: In this study, we reconstruct water-column oxygen availability during the deposition of Late Permian shales (Wuchiapingian to approximately early Changhsingian) using the geochemistry and morphology of sedimentary pyrite (FeS2). Deposition of the shales occurred prior to the end-Permian mass extinction within the southern Neo-Tethys Ocean (Spiti region, Himachal Pradesh, India). We found that the variability of pyritic sulfur to organic carbon (Spyr/Corg) and the pyritic sulfur isotopic composition (δ34Spyr) did not record changes in oxygen availability at Spiti sections. This was due to the removal of original pyritic sulfur by modern oxidative weathering and diagenetic pyrite formation which overwhelmed the original δ34Spyr values. However, pyrite framboid size distributions was a reliable recorder of paleoredox conditions. The degree of oxygen limitation varied with multiple transient euxinic events interrupting a predominantly oxic-dysoxic trend near the top of the Gungri Formation upper member (approximately late Wuchiapingian to early Changhsingian). These transient euxinic intervals provide important insight and regional evidence of environmental stress and instability in the southern Neo-Tethys well prior to the end-Permian mass extinction.

21704. 题目: Release of polycyclic aromatic hydrocarbons from biochar fine particles in simulated lung fluids: Implications for bioavailability and risks of airborne aromatics
文章编号: N18112907
期刊: Science of The Total Environment
作者: Xinlei Liu, Rong Ji, Yu Shi, Fang Wang, Wei Chen
更新时间: 2018-11-29
摘要: Airborne carbonaceous fine particles, such as soot and biochar, represent a significant fraction of air particulate matter and have received widespread concern due to their health effects. Atmospheric carbonaceous particles can contain high concentration of polycyclic aromatic hydrocarbons (PAHs), and may pose significant health risks when carried into respiratory system from inhalation of particulates. In this study, the bioaccessibility of two PAH compounds, phenanthrene and pyrene, bound to biochar fine particles was assessed by examining their release in two simulated lung fluids: Gamble's solution and artificial lysosomal fluid (ALF). We observed that only 0.47 to 0.75% of biochar-bound PAHs were released in the simulated lung fluids, most likely due to the physical entrapment of PAH molecules in the micropore regimes of biochar, resulting in strong desorption hysteresis, even though apparent desorption equilibrium was reached within 30 min, well within the average clearance time of particulate matter in lung system. The inorganic and organic salts in the simulated lung fluids were found to inhibit the release of PAHs by exerting the pore blockage effect and salting-out effect. Moreover, the low molecular weight organic acids (LMWOAs) in the lung fluids further inhibited PAH release by increasing the micropore volume and surface area of biochar fine particles. When taking into account the inhibited release, the estimated carcinogenic risks of biochar-bound PAHs are typically low, even under extreme conditions wherein both biochar concentrations and PAH loadings on biochar are very high. An important implication is that contaminant bioavailability needs to be taken into account when assessing the risks of the contaminants bound to airborne carbonaceous materials.
图文摘要:

21705. 题目: Effects of arbuscular mycorrhizal fungi, biochar and cadmium on the yield and element uptake of Medicago sativa
文章编号: N18112906
期刊: Science of The Total Environment
作者: Fengge Zhang, Mohan Liu, Yang Li, Yeye Che, Yan Xiao
更新时间: 2018-11-29
摘要: The synergistic effects of arbuscular mycorrhizal fungi (AMF) inoculation and biochar application on plant growth and heavy metal uptake remain unclear. A pot experiment was carried out to investigate the influence of AMF inoculation, biochar and cadmium (Cd) addition on the growth, nutrient and cadmium uptake of Medicago sativa, as well as soil biological and chemical characteristics. In comparison to the non-Cd pollution treatment, Cd addition significantly decreased mycorrhizal colonization, biomass, and N, P, Ca and Mg contents of shoots and roots in the absence of biochar. Biochar amendment did not increase mycorrhizal colonization at either Cd levels. Regardless of the biochar amendment, AMF inoculation significantly promoted contents of N and P in plant shoots grown in the Cd-contaminated soils. Nevertheless, in the presence of Cd pollution, biochar dramatically elevated the biomass and N, P, K and Ca contents of plant tissues in both AMF inoculation treatments. Biochar addition significantly reduced soil DTPA-extracted Cd. The treatments with AMF inoculation and biochar amendment showed the lowest shoot Cd concentrations and contents, highest plant tissue N and P contents in the Cd addition group. These results suggested that combined use of AMF inoculation and biochar amendment had significant synergistic effects not only on nutrient uptake but also on the reduction in cadmium uptake of alfalfa grown in Cd-polluted soil.
图文摘要:

21706. 题目: Multiple human pressures in coastal habitats: variation of meiofaunal assemblages associated with sewage discharge in a post-industrial area
文章编号: N18112905
期刊: Science of The Total Environment
作者: I. Bertocci, A. Dell'Anno, L. Musco, C. Gambi, V. Saggiomo, M. Cannavacciuolo, M. Lo Martire, A. Passarelli, G. Zazo, R. Danovaro
更新时间: 2018-11-29
摘要: Marine ecosystems are globally threatened by human activities, but some areas, such as those affected by abandoned industrial plants, show an overlap of acute and chronic impacts, which determine a considerable deterioration of their health status. Here we report the results of a research conducted on coastal sewers that discharge their loads in the highly contaminated area of Bagnoli-Coroglio (Tyrrhenian Sea, Western Mediterranean). The sampling area is characterized by heavy industrial activities (a steel plant using coal, iron and limestone) started in 1905 and ceased in 1990, which left widespread heavy metals and hydrocarbon contamination. After taking into account the potential influence of sediment grain size ranges through their inclusion as covariates in the analysis, we tested the potential impact of sewage discharge on the total abundance and multivariate structure of meiofaunal assemblages, as well as on the abundance of single taxa. The organic matter was analysed in terms of total phytopigment and biopolymeric carbon concentrations. Nematoda, Copepoda (including their nauplii), and Tardigrada were the most abundant meiofaunal taxa at all sites, but nematodes did not show a consistent pattern relative to the sewage outfalls. However, the sewer located in the historically most contaminated area showed a minimal abundance of all taxa, including nematodes, while copepods were relatively less abundant at the two southernmost sewers. Comparing the north vs. south site of the sewers, higher meiofaunal abundances were observed in the southward part, likely as a result of the local circulation. The results of this study indicate the general adaptation of meiofauna to multiple stressors (sewage discharge, superimposed to chronic industrial contamination) and its likely modulation by other local processes. They also provide relevant baseline information for future restoration interventions that would take into account the spatial variation of target organisms as needed.
图文摘要:

21707. 题目: Unexpected higher decomposition of soil organic matter during cold fallow season in temperate rice paddy
文章编号: N18112904
期刊: Soil and Tillage Research
作者: Hyo Suk Gwon, Isra Khan Dawar, Young Eun Yoon, Yong Bok Lee, Pil Joo Kim, Hyun Young Hwang
更新时间: 2018-11-29
摘要: In temperate paddy fields, rice is generally cultivated under flooding for 100–140 days during summer season, and thereafter, the soil is left without management under dried soil condition during cold fallow season. In this area rice straw is mostly removed for cattle feeding. Therefore, soil organic carbon (SOC) stock could be decreased with conventional practices, but the seasonal changes of SOC stock have not been evaluated well. To investigate SOC stock changes in temperate rice paddy, two seasonal C balances during rice cropping and fallow season were compared by the net ecosystem C budget (NECB) in the chemical fertilizer (control) and two different green manure treatments for three years. In the control treatment only chemical fertilizer was conventionally fertilized for rice cropping, but maintained without human control during the fallow season. In two green manure treatments, barley and hairy vetch (hereafter, vetch) were cultivated during the fallow season, and their whole biomasses were incorporated before rice transplanting. The conventional soil management with only chemical fertilization decreased small level of SOC stock (minus 0.70–0.84 Mg C ha−1 y−1 of NECB), which was attributed by high harvest removal (approximately 70% of total C input) and mineralized C loss (30%). Cover cropping and its biomass recycling as green manure was effective to increase SOC stock. High C/N ratio of non-leguminous barley produced high biomass yield, and its biomass incorporation significantly increased SOC stock with 1.21–3.43 Mg C ha−1 y−1 of annual NECB. In comparison low C/N ratio of leguminous vetch application increased slightly SOC stock (0.17–1.34 Mg C ha−1 y−1 of NECB), due to low biomass productivity and high mineralized C loss. However, irrespective with fertilization background, approximately 70% of mineralized C loss were occurred during the cold fallow season. Rice grain yields were similar between the control and hairy vetch treatment, but around 10% lower in barley treatment. Conclusively, high C/N ratio of cover crop cultivation during the fallow season could be better to increase SOC stock in mono-rice paddy, but additional nutrient management to increase rice productivity should be developed for barley utilization as green manure.

21708. 题目: A new experimental platform connecting the rhizosphere priming effect with CO2 fluxes of plant-soil systems
文章编号: N18112903
期刊: Soil Biology and Biochemistry
作者: Camille Cros, Gaël Alvarez, Frida Keuper, Sébastien Fontaine
更新时间: 2018-11-29
摘要: Forty years of research on the rhizosphere priming effect (RPE) has demonstrated the potentially large increase (up to a factor 3) of soil organic matter mineralization induced by plant roots, but failed to directly quantify its contribution to the carbon (C) balance. Combining continuous CO2 flux measurements with RPE measurements has thus far been technically challenging. Here, we present an experimental platform of 40 mesocosms (volume = 88L; surface = 0.049 m2), including a 13C-labeled CO2 air-production system with a maximum capacity of 4 m3 min−1 and customizable labeling intensity. For this study, 13C depleted fossil C was used as source of labeled CO2 and the experiment was run for 250 days. Continuous net CO2-exchange measurements allowed us to estimate net ecosystem productivity, gross primary production and ecosystem respiration of the studied plant-soil systems. The RPE was regularly (bi-monthly to monthly) quantified by measuring the accumulation and isotopic composition of CO2 in dark chambers placed over the mesocosms. Our results show a good relationship between night plant-soil respiration (from continuous CO2-exchange measurements) and dark plant-soil respiration (from CO2 accumulation in dark chambers). This result suggests that our estimates of RPE and plant-soil fluxes based on the different methods are comparable. Preliminary results obtained in spring with grasses cultivated under ambient or elevated CO2 indicate that the RPE represents 1.22 ± 0.16% of gross primary production and 4.64 ± 1.12% of ecosystem respiration. The RPE estimates may have an uncertainty linked to the possible deviation in delta 13C between C sources (soil or plant) and released CO2 from these sources. We performed a sensitivity analysis on how the variation in intensity of isotopic labeling (difference in delta 13C between plant and soil) affects the uncertainty of RPE estimates considering 1‰ delta 13C deviation. Estimation of the RPE with an uncertainty lower than 10% of the estimated value requires a labeling intensity higher than 60‰. The developed platform will help to scale up the study of the RPE control on C cycling to the ecosystem level.

21709. 题目: Effects of shrubs on soil nutrients and enzymatic activities over a 0–100 cm soil profile in the desert-loess transition zone
文章编号: N18112902
期刊: CATENA
作者: Yufei Yao, Mingan Shao, Xiaoli Fu, Xiang Wang, Xiaorong Wei
更新时间: 2018-11-29
摘要: The creation of “fertile islands” beneath shrubs in dryland ecosystems has been widely reported worldwide and is the major factor influencing ecosystem structure and function. However, studies investigating whether and how shrubs affect soil biogeochemical cycles in deep soil layers are relatively limited. In this study, we examined the vertical distribution of the soil nutrient contents and enzymatic activities at the 0–100 cm soil profiles beneath three common xerophytic shrubs (Artemisia ordosica, Caragana korshinskii and Salix psammophila) and in interspace bare soils in a transition zone from desert to loess in the north of China. The soil metrics included the contents of organic carbon, total nitrogen, total phosphorus, nitrate and ammonium nitrogen, available phosphorus and potassium, and the activities of saccharase, urease, alkaline phosphatase and amylase. We found that the contents of organic carbon, total nitrogen and available potassium, and the activities of saccharase, urease and alkaline phosphatase were higher in the soils beneath shrubs than in the interspace bare areas, but these differences only occurred in the 0–10 cm soil profile but not in the soils below the depth of 10 cm. The soil quality index was consistently improved among the three shrub species in the topsoil. In addition, the soil nutrients were positively correlated with enzymatic activities, and the organic carbon content explained approximately 50% of the variations in the enzymatic activities. Collectively, our results demonstrated that the establishment of xerophytic shrubs improved the soil chemical and biological conditions in the desert-loess transition region, and the effect was restricted to the 0–10 cm soil layer.

21710. 题目: Estimating the soil respiration under different land uses using artificial neural network and linear regression models
文章编号: N18112901
期刊: CATENA
作者: Mitra Ebrahimi, Mohammad Reza Sarikhani, Ali Akbar Safari Sinegani, Abbas Ahmadi, Saskia Keesstra
更新时间: 2018-11-29
摘要: Soil respiration is a biological process in microbes that convert organic carbon to atmospheric CO2. This process is considered to be one of the largest global carbon fluxes and is affected by different physicochemical and biological properties of soil, land use, vegetation types and climate patterns. Soil respiration recently received much attention, and it could be measured in two states basal respiration (BR) and substrate induced respiration (SIR) which together gives a good representation of the general soil microbial activity. The aim of this study was to estimate the BR and SIR of 150 data points obtained from soil samples collected from the surface to 20 cm of depth under different land use categories using the Artificial Neural Network (ANN) and Linear Regression Methodology (LRM). This study is bringing data from an arid area, and there is little information on this issue. Soil samples were chosen from three provinces of Iran, with humid subtropical and semi-arid climate patterns. In each soil sample a variety of characteristics were measured: soil texture, pH, electrical conductivity (EC), calcium carbonate equivalent (CCE), organic carbon (OC), OC fractionation data e.g. light fraction OC (LOC), heavy fraction OC (HOC), cold water extractable OC (COC) and warm water extractable OC (WOC), population of fungi, bacteria, actinomycete, BR and SIR. Our goal was to use the most efficient ANN-model to predict soil respiration with simple soil data and annual precipitation (AP) and mean annual temperature (MAT) and compare it with LRM. Our results indicated that for an ANN model containing all the measured soil parameters (14 variables), the R2 and RMSE values for BR prediction were 0.64 and 0.05 while these statistical indicators for SIR obtained 0.58 and 0.15, respectively; whereas the addition of AP and MAT data to this model (16 variables) caused a decrease in statistical indicators. When the R2 and RMSE values of the BR-ANN and SIR-ANN predicted using an ANN model with only 7 variables (including OC, pH, EC, CCE and soil texture) they were estimated to be 0.66, 0.043 and 0.52, 0.16, respectively. Overall, LRM in comparison to ANN had a lower R2. Therefore, the results show that ANN modeling is a reliable method for predicting soil respiration, even when based on easy to measure data. Our results revealed that highest and lowest BR and SIR were recorded in rice paddy soils and saline lands, respectively. In total, soil respiration (BR: 0.09 vs 0.06 and SIR: 0.46 vs 0.32 mg CO2 g−1 day−1) was higher in agricultural land compared to natural covered land.

21711. 题目: Climate-driven thresholds in reactive mineral retention of soil carbon at the global scale
文章编号: N18112821
期刊: Nature Climate Change
作者: Marc G. Kramer, Oliver A. Chadwick
更新时间: 2018-11-28
摘要: Soil organic matter can release carbon dioxide to the atmosphere as the climate warms. Organic matter sorbed to reactive (iron- and aluminium-bearing) soil minerals is an important mechanism for long-term carbon storage. However, the global distribution of mineral-stored carbon across climate zones and consequently its overall contribution to the global soil carbon pool is poorly known. We measured carbon held by reactive minerals across a broad range of climates. Carbon retained by reactive minerals was found to contribute between 3 and 72% of organic carbon found in mineral soil, depending on mean annual precipitation and potential evapotranspiration. Globally, we estimate ~600 Gt of soil carbon is retained by reactive minerals, with most occurring in wet forested biomes. For many biomes, the fraction of organic carbon retained by reactive minerals is responsive to slight shifts in effective moisture, suggesting high sensitivity to future changes in climate.

21712. 题目: Abiotic formation of condensed carbonaceous matter in the hydrating oceanic crust
文章编号: N18112820
期刊: Nature Communications
作者: Marie Catherine Sforna, Daniele Brunelli, Céline Pisapia, Valerio Pasini, Daniele Malferrari, Bénédicte Ménez
更新时间: 2018-11-28
摘要: Thermodynamic modeling has recently suggested that condensed carbonaceous matter should be the dominant product of abiotic organic synthesis during serpentinization, although it has not yet been described in natural serpentinites. Here we report evidence for three distinct types of abiotic condensed carbonaceous matter in paragenetic equilibrium with low-temperature mineralogical assemblages hosted by magma-impregnated, mantle-derived, serpentinites of the Ligurian Tethyan ophiolite. The first type coats hydroandraditic garnets in bastitized pyroxenes and bears mainly aliphatic chains. The second type forms small aggregates (~2 µm) associated with the alteration rims of spinel and plagioclase. The third type appears as large aggregates (~100–200 µm), bearing aromatic carbon and short aliphatic chains associated with saponite and hematite assemblage after plagioclase. These assemblages result from successive alteration at decreasing temperature and increasing oxygen fugacity. They affect a hybrid mafic-ultramafic paragenesis commonly occurring in the lower oceanic crust, pointing to ubiquity of the highlighted process during serpentinization

21713. 题目: Mercury Stable Isotope Fractionation during Abiotic Dark Oxidation in the Presence of Thiols and Natural Organic Matter
文章编号: N18112819
期刊: Environmental Science & Technology
作者: Wang Zheng, Jason D. Demers, Xia Lu, Bridget A. Bergquist, Ariel D. Anbar, Joel D. Blum, Baohua Gu
更新时间: 2018-11-28
摘要: Mercury (Hg) stable isotope fractionation has been widely used to trace Hg sources and transformations in the environment, although many important fractionation processes remain unknown. Here, we describe Hg isotope fractionation during the abiotic dark oxidation of dissolved elemental Hg(0) in the presence of thiol compounds and natural humic acid. We observe equilibrium mass-dependent fractionation (MDF) with enrichment of heavier isotopes in the oxidized Hg(II) and a small negative mass-independent fractionation (MIF) owing to nuclear volume effects. The measured enrichment factors for MDF and MIF (ε202Hg and E199Hg) ranged from 1.10‰ to 1.56‰ and from −0.16‰ to −0.18‰, respectively, and agreed well with theoretically predicted values for equilibrium fractionation between Hg(0) and thiol-bound Hg(II). We suggest that the observed equilibrium fractionation was likely controlled by isotope exchange between Hg(0) and Hg(II) following the production of the Hg(II)–thiol complex. However, significantly attenuated isotope fractionation was observed during the initial stage of Hg(0) oxidation by humic acid and attributed to the kinetic isotope effect (KIE). This research provides additional experimental constraints on interpreting Hg isotope signatures with important implications for the use of Hg isotope fractionation as a tracer of the Hg biogeochemical cycle.
图文摘要:

21714. 题目: Mechanisms of Interaction between Persulfate and Soil Constituents: Activation, Free Radical Formation, Conversion, and Identification
文章编号: N18112818
期刊: Environmental Science & Technology
作者: Guodong Fang, Xiru Chen, Wenhui Wu, Cun Liu, Dionysios D. Dionysiou, Tingting Fan, Yujun Wang, Changyin Zhu, Dongmei Zhou
更新时间: 2018-11-28
摘要: Persulfate-based in situ chemical oxidation (ISCO) for soil remediation has received great attention in recent years. However, the mechanisms of interaction between persulfate (PS) and soil constituents are not fully understood. In this study, PS decomposition, activation, free radical formation and conversion processes in 10 different soils were examined. The results showed that soil organic matter (SOM) was the dominant factor affecting PS decomposition in soil, but Fe/Mn-oxides were mainly responsible for PS decomposition when SOM was removed. Electron paramagnetic resonance (EPR) spectroscopy analysis showed that sulfate radicals (SO4•–) and hydroxyl radicals (•OH) generated from PS decomposition subsequently react with SOM to produce alkyl-like radicals (R), and this process is dependent on SOM content. R and SO4•–/•OH radicals predominated in soil with high and low SOM, respectively, and all three radicals coexist in soil with medium SOM. Chemical probe analysis further identified the types of radicals, and R can reductively degrade hexachloroethane in high SOM soil, while SO4•– and •OH oxidatively degrade phenol in low SOM soil. These findings provide valuable information for PS-ISCO, and new insight into the role of SOM in the remediation of contaminated soil.
图文摘要:

21715. 题目: Determination and Prediction of Zinc Speciation in Estuaries
文章编号: N18112817
期刊: Environmental Science & Technology
作者: Holly B. C. Pearson, Sean D. W. Comber, Charlotte B Braungardt, Paul Worsfold, Anthony Stockdale, Stephen Lofts
更新时间: 2018-11-28
摘要: Lowering of the estuarine Environmental Quality Standard for zinc in the UK to 121 nM reflects rising concern regarding zinc in ecosystems and is driving the need to better understand its fate and behavior and to develop and parametrize speciation models to predict the metal species present. For the first time, an extensive data set has been gathered for the speciation of zinc within an estuarine system with supporting physicochemical characterization, in particular dissolved organic carbon. WHAM/Model VII and Visual MINTEQ speciation models were used to simulate zinc speciation, using a combination of measured complexation variables and available defaults. Data for the five estuarine transects from freshwater to seawater endmembers showed very variable patterns of zinc speciation depending on river flows, seasons, and potential variations in metal and ligand inputs from in situ and ex situ sources. There were no clear relationships between free zinc ion concentration [Zn2+] and measured variables such as DOC concentration, humic and biological indices. Simulations of [Zn2+] carried out with both models at high salinities or by inputting site specific complexation capacities were successful, but overestimated [Zn2+] in low salinity waters, probably owing to an underestimation of the complexation strength of the ligands present. Uncertainties in predicted [Zn2+] are consistently smaller than standard deviations of the measured values, suggesting that the accuracy of the measurements is more critical than model uncertainty in evaluating the predictions.
图文摘要:

21716. 题目: Thermal conversion of a promising phytoremediation plant (Symphytum officinale L.) into biochar: dynamic of potentially toxic elements and environmental acceptability assessment of the biochar
文章编号: N18112816
期刊: Bioresource Technology
作者: Juan Du, Lei Zhang, Tao Liu, Ran Xiao, Ronghua Li, Di Guo, Ling Qiu, Xuanmin Yang, Zengqiang Zhang
更新时间: 2018-11-28
摘要: Symphytum officinale L., as a hyperaccumulator, was pyrolyzed into biochar at 350, 550, and 750 °C, respectively. PTEs could be enriched in biochars except Cd volatilized greatly at 750 °C. In order to evaluate the environmental acceptability of biochars, a series of sequential and single extractions and biochar oxidation procedures were performed for simulating different environmental conditions. There was a sharp decline in PTEs release under various conditions when the temperature above 550 °C, indicating PTEs might transform into more stable forms at higher temperature. Thus, increasing the pyrolysis temperature is helpful for reducing biochar phytotoxicity, suppressing biochar leaching and improving biochar environmental safety. Moreover, the economic feasibility analysis of the biochar confirmed the practicability of it. Findings from this work illustrated that biochars pyrolyzed from Symphytum officinale L. at the temperature higher than 550 °C might be environmental acceptable, which is beneficial for biochar application.
图文摘要:

21717. 题目: Effects of biomass pyrolysis derived wood vinegar (WVG) on extracellular polymeric substances and performances of activated sludge
文章编号: N18112815
期刊: Bioresource Technology
作者: Fang Zhang, Haiping Yang, Dabin Guo, Shihong Zhang, Hanping Chen, Jing'ai Shao
更新时间: 2018-11-28
摘要: The effects of wood vinegar (WVG) on extracellular polymeric substances (EPS), and flocculation, sedimentation and dewatering performances of activated sludge were investigated in sequencing batch reactor (SBR) process. Results showed that polysaccharide (PS) and DNA were accounted for the largest and smallest proportion of EPS, respectively. With WVG injection, productions of soluble EPS (S-EPS), loosely bound EPS (LB-EPS), tightly bound EPS (TB-EPS), protein (PN), PS, and DNA were significantly increased. The optimal WVG concentration was found as 4μl/l. The effects of WVG on different types of EPS followed an order of LB-EPS>TB-EPS>S-EPS. According to batch and long-term SBR operations, WVG could increase the biomass amount of activated sludge, which was beneficial to improve sewage treatment efficiencies. However, WVG showed negative impact on flocculation, sedimentation, and dewatering performance of activated sludge.

21718. 题目: Polyethyleneimine and carbon disulfide co-modified alkaline lignin for removal of Pb2 +  ions from water
文章编号: N18112814
期刊: Chemical Engineering Journal
作者: Qiaorui Wang, Chunli Zheng, Zhenxing Shen, Qiang Lu, Chi He, Tian C. Zhang, Jianhui Liu
更新时间: 2018-11-28
摘要: This paper reports the efficient removal of Pb2 + ions from water by modified alkaline lignin (MAL), in which alkaline lignin was used as the raw material and ornamented with amine/imine (–NH2/–NH) and dithiocarbamate (–CSS) groups by using polyethyleneimine (PEI) and carbon disulfide (CS2) as the modifier. The pseudo-second-order model and Langmuir model expressed the adsorption kinetics and isotherm well, indicating the adsorption of Pb2 + ions on MAL was a chemisorption and monolayer. The maximum adsorption amount (qm) of MAL towards Pb2 + ions was 79.9 mg/g, significantly higher than that of other reported biomass-based-sorbents such as Hamimelon peels (7.9 mg/g), dairy manure-derived biochar (37.8 mg/g), and acid-treated avocado kernel seeds (21.8 mg/g). Even after six continuous adsorption–desorption cycles, the values of qm for the regenerated MAL at each cycle were still obviously higher than those aforementioned sorbents. The binding affinity of different groups of MAL towards Pb2 + ions followed the sequence: C–N > –NH2 > N–H/O–H > C–S > CS. This work not only gave a comprehensive picture of the adsorption/desorption mechanism of Pb2 + ions on MAL but also evaluated the reusing ability of MAL. These results may provide insights for the further studies on the subsequent construction of devices to be used in bench- and pilot-scale experiments.
图文摘要:

21719. 题目: High efficient removal of bisphenol A in a peroxymonosulfate/iron functionalized biochar system: Mechanistic elucidation and quantification of the contributors
文章编号: N18112813
期刊: Chemical Engineering Journal
作者: Shun-Feng Jiang, Li-Li Ling, Wen-Jing Chen, Wu-Jun Liu, De-Chang Li, Hong Jiang
更新时间: 2018-11-28
摘要: Activation of peroxymonosulfate (PMS) to degrade recalcitrant organic pollutants has attracted much attention, however, this process usually needs expensive or toxic catalysts. Herein, we prepared a Fe functionalized biochar composite that contain Fe0, porous carbon with abundant functional groups and nanofibers (Fe-BC-700) to activate PMS and efficiently remove bisphenol A (BPA). The contribution of different participants in the complicated system involving Fe species, carbon composites, and radicals and nonradicals were quantitatively investigated. Under optimal conditions (0.2 g/L PMS and 0.15 g/L catalyst), 20 mg/L of BPA can be completely removed in 5 min by Fe-BC-700. The effects including the activation of PMS by Fe species to produce sulfate radicals (SO4), the electron transfer by the nanofiber-mesoporous carbon structure, and the inherent persistent free radicals (PFR) in biochar, were demonstrated to contribute to the high performance. A series of contrast experiments showed that PMS activated by Fe contributed to about 36% of BPA degradation, while the carbon composites, especially carbon nanofibers contributed to 17%, and the other 47% was ascribed to the adsorption of carbon composites (may further undergoing degradation). Meanwhile, the degradation by SO4 accounted for about 23% (by quenching experiments), while the nonradical pathway contributed to 30%. This work suggests that the non-activation factors in PMS/porous catalyst/pollutant system cannot be neglected.
图文摘要:

21720. 题目: Enhancement of dewaterability and heavy metals solubilization of waste activated sludge conditioned by natural vanadium-titanium magnetite-activated peroxymonosulfate oxidation with rice husk
文章编号: N18112812
期刊: Chemical Engineering Journal
作者: Changgeng Liu
更新时间: 2018-11-28
摘要: In this work, natural vanadium-titanium magnetite-activated peroxymonosulfate (VTM-PMS) oxidation coupled with rice husk (RH) as skeleton builder (VTM-PMS-RH) was employed to enhance sludge dewaterability for the first time. The optimal dosages of PMS, VTM, and RH were 200 mg/g total suspended solids (TSS), 1 g/g TSS, and 200 mg/g TSS, respectively. Under optimal conditions, capillary suction time (CST) reduction and water content of sludge cake (WC) were 82.1% and 72.9% after VTM-PMS conditioning, respectively, which further reached the values of 94.8% and 63.4% when coupled with RH treatment. Cycle experiments demonstrated that VTM reusability in VTM-PMS system for dewatering sludge was desirable. Based on sludge physicochemical properties after conditioning (i.e., extracellular polymeric substances (EPS), zeta potential, dissolved organic carbon (DOC), total nitrogen (TN), and volatile suspended solids (VSS) reduction), VTM-PMS oxidation shows the merits of EPS degradation, sludge disintegration, and charge neutralization. In addition, the transformation behaviors of heavy metals (HMs) in sludge after conditioning were investigated according to total HMs contents, speciation distribution, and leaching tests. Through conditioning, total HMs contents (Cu, Zn, Cr, and Pb) in liquid phase increased while were adverse in solid phase. The leaching toxicity reductions were 78%, 83%, 60%, and 100% for Cu, Zn, Cr, and Pb, respectively, obtained by VTM-PMS-RH conditioning. Meanwhile, the chemical speciation distribution of HMs in sludge was changed and transformed into more stable forms, as well as the environmental risk of HMs decreased. These results suggest that VTM-PMS-RH process has a synergistic contribution to the environmental risk reduction of HMs and their immobilization enhancement. Therefore, VTM-PMS-RH process is a promising alternative for sludge conditioning in terms of the enhancement of dewaterability and HMs solubilization.
图文摘要:

 共 23819 条记录  本页 20 条  本页从 21701-21720 条  1086/1191页  首页 上一页  1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091  下一页  末页   

本数据库数据来源自各期刊,所有权归属各期刊。数据仅供分享学习,不作商业用途,特此申明。