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17501. 题目: Stabilization of per- and polyfluoroalkyl substances (PFASs) with colloidal activated carbon (PlumeStop®) as a function of soil clay and organic matter content
文章编号: N19090304
期刊: Journal of Environmental Management
作者: M. Sorengard, Dan Berggren Kleja, Lutz Ahrens
更新时间: 2019-09-03
摘要: The global problem of contamination of drinking water sources and the aquatic environment with per- and polyfluoroalkyl substances (PFASs) originating from highly contaminated soils is addressed in this study. For the first time, a colloidal activated carbon (AC) product (PlumeStop®) was systematically assessed for PFASs stabilization in soil. Colloidal (particle size 0.1–1.1 μm) AC has the advantage that field application is non-intrusive, comprising injection under high pressure in situ at PFAS-contaminated soil hotspots. In the assessment, 10 different soil mixtures with gradually increasing organic carbon and clay fractions were spiked with 18 different PFASs of varying perfluorocarbon chain length and four different functional groups and aged for one year. Equilibrium leaching tests showed that the ability of colloidal AC to increase sorption of PFASs to soil was highly dependent on PFAS perfluorocarbon chain length. The best treatment efficiency was observed for perfluorocarbon chain lengths 6–7 at which colloidal AC resulted in sorption of 81%, 85%, and 86% for perfluorooctanoate (PFOA), 6:2 fluorotelomer sulfonate (6:2 FTSA) and perfluorohexane sulfonate, (PFHxS), respectively. Sorption of individual PFASs decreased significantly (p < 0.05) with increasing organic carbon content in soil treated with colloidal AC indicating stearic hindrance of the ACs pore structure. On the other hand, the sorption of the majority of PFASs increased significantly (p < 0.05) with increasing clay content in colloidal AC-treated soil, which can be explained by increase in surface area that colloidal AC can sorb to. Overall, the results indicate that the colloidal AC product tested can be useful in remediation approaches for certain PFASs under specific field conditions and PFAS contamination.
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17502. 题目: The discrepant mobility of antibiotic resistant genes: Evidence from their spatial distribution in sewage sludge flocs
文章编号: N19090303
期刊: Science of The Total Environment
作者: Pinjing He, Yizhou Zhou, Liming Shao, Jinghua Huang, Zhan Yang, Fan Lü
更新时间: 2019-09-03
摘要: The present study stratified excess activated sludge from six municipal wastewater treatment plants into four extracellular fractions including supernatant, slime, slightly-bond extracellular polymeric substances (LB-EPS) and tightly-bond EPS (TB-EPS) and one intracellular fraction (pellet) according to their different degrees of tight binding to sludge microbial aggregates and determined the abundance of seven antibiotic resistance genes (ARGs) (sul-I, sul-II, tet-C, tet-X, blaTEM, mefA and cat) and one mobile genetic elements (MGEs) (IntI-1) in each fraction. Extracellular ARGs were found to make up 0.1% - 74.2% of total ARGs, while the ratio of extracellular DNA to total DNA was only 1.2% - 4.2%, implying that EPS was a major ARG reservoir in sewage sludge. The genes of sul-I, tet-C and mefA have the highest mobility owing to a large proportion ranging from 0.5% to 32.7% in the fractions of LB-EPS, slime and supernatant, which indicates an increased risk of mediating the transfer of ARGs to environment. Comparatively, the proportion of blaTEM in the TB-EPS of sludge accounted for 0.3%–34.9% and caused limited-mobility. Sul-II, tet-X and cat and IntI-1, made up approximately 82.6% - 99.6% proportion in the cells, and were thus less mobile. This study proposes that ARGs and MGEs can have different mobilities. Those located in the outermost layers of sludge have a higher mobility potential of propagation into the natural environment during wastewater treatment and sludge utilization, leading to an increased risk of transferability.
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17503. 题目: Plant diversity and soil stoichiometry regulates the changes in multifunctionality during pine temperate forest secondary succession
文章编号: N19090302
期刊: Science of The Total Environment
作者: Manuel Esteban Lucas-Borja, Manuel Delgado-Baquerizo
更新时间: 2019-09-03
摘要: The shift in ecosystem multifunctionality during ecosystem succession (years to decades) remains largely unexplored. In this study, we used a 120-year-old pine temperate forest chronosequence (1: 1–19 years, stage 2: 20–39 years, stage 3: 40–59 years, stage 4: 60–79 years, stage 5: 80–99 years, stage 6: 100–120 years) to evaluate the role that time plays in shaping ecosystem multifunctionality (nutrient cycling, carbon stocks, water regulation, decomposition and wood production), and found that, over the first century, ecosystem functioning gradually increased every ~50 years. Such a result was maintained for individual groups of ecosystem functions and services including nutrient cycling, carbon stocks, decomposition and wood production. Plant diversity and soil stoichiometry (C:N ratio) were the major environmental predictors for the changes in ecosystem multifunctionality during forest secondary succession. Plant diversity increased during ecosystem succession and was positively related to ecosystem multifunctionality. The soil C:N ratio decreased during ecosystem succession and was negatively related to multifunctionality. Our results suggest that increases in aboveground resource heterogeneity (higher plant diversity) and organic matter quality (lower soil C:N ratios) could help explain the increases in multifunctionality over a century of forest development. Our work illustrates the importance of time in shaping multifunctionality during the first century of ecosystem succession, and further provide important insights for the management of temperate forest ecosystems.
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17504. 题目: Catalytic ozonation of emerging pollutant and reduction of toxic by-products in secondary effluent matrix and effluent organic matter reaction activity
文章编号: N19090301
期刊: Water Research
作者: Yuting Zhang, Yechen An, Chao Liu, Yiping Wang, Zilong Song, Yanning Li, Weidong Meng, Fei Qi, Bingbing Xu, Jean-Philippe Croue, Donghai Yuan, Amir Ikhlaq
更新时间: 2019-09-03
摘要: In this study, the performance of LaCoO3 (LCO) catalytic ozonation was evaluated comprehensively, including the degradation efficiency of benzotriazole (BZA) as a typical emerging pollutant, toxic bromate reduction and the disinfection by-products (DBPs) precursors removal ability in effluent organic matter (EfOM), as well as EfOM reactive activity in catalytic ozonation. Additionally, the reduction of toxic halogenated by-products in (catalytic) ozonation was reported, which was not focused on previous researches before. Results showed that LCO catalytic ozonation improved the removal efficiency of BZA, UV254 and SUVA via enhanced HO· formation. Interestingly, LCO catalytic ozonation showed the ability on the reduction of aldehydes and toxic halogenated organic by-products. Moreover, the formed [trichloromethane (TCM)], [bromochloroacetonitrile (BCAN)] and [dichloroacetamide (DCAcAm)] decreased significantly in catalytic ozonation. Catalytic ozonation was also able to remove DBPs precursors to decline the formation of DBPs, such as TCM, bromodichloromethane (BDCM), trichloroacetonitrile (TCAN) and trichloronitromethane (TCNM). This process was involved in the transformation of EfOM in catalytic ozonation, which was confirmed by multi-spectrum methods, two-dimensional correlation spectroscopy (2D-COS) and hetero-spectral 2D-COS. In summary, LCO was shown to be an effective catalyst to improve the performance of the sole ozonation on the removal of emerging contaminants and DBPs precursors, as well as toxic by-products reduction. Additionally, the strategy of toxic by-products reduction in catalytic ozonation was proposed. Results indicated this technology was an important contribution on removal of refractory organics and formation of toxic by-products in water supply and wastewater treatment industry.
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17505. 题目: Assessing the carbon assimilation and production of benthic archaeal lipid biomarkers using lipid-RIP
文章编号: N19090209
期刊: Geochimica et Cosmochimica Acta
作者: Thomas W. Evans, Sarah Coffinet, Martin Könneke, Julius S. Lipp, Kevin W. Becker, Marcus Elvert, Verena Heuer, Kai-Uwe Hinrichs
更新时间: 2019-09-02
摘要: Distributional patterns of intact polar lipids (IPLs) suggest that archaea are abundant in marine subsurface sediments. However, the production of archaeal lipids remains largely unresolved. We performed a lipid radioisotope probing (lipid-RIP) experiment using 14C-bicarbonate and 2-14C-acetate with surface and methanogenic marine sediments from the Rhone delta (Mediterranean Sea) to investigate mechanisms of carbon assimilation and to assess biomass production of benthic archaea. The direct determination of carbon assimilation rates into diagnostic IPLs in the experiments with 14C-bicarbonate were up to 9 times higher than in the incubations with 2-14C-acetate, implying that autotrophy is an important carbon pathway for the benthic archaea in the Rhone delta sediments. Production rates of polyglycosidic archaeols (AR) were one to two orders of magnitude higher than those of mono- and polyglycosidic glycerol dialkyl glycerol tetraethers (GDGTs), suggesting that the former IPLs are good biomarkers for active benthic archaea in marine sediments. In contrast, the low production rates of the monoglycosidic AR and GDGTs, indicates that a large fraction of these IPLs may represent fossil sedimentary remains from the water column. Unexpectedly, the lipid production rates of AR and GDGT core lipids (CLs) were similar to those of polyglycosidic IPLs. Considering the relatively short period of incubation (21 days), this suggests that CLs may be actively synthesized by benthic archaea in marine sediments and are not exclusively formed from the degradation of IPL precursors.

17506. 题目: Group I alkenones and Isochrysidales in the world’s largest maar lakes and their potential paleoclimate applications
文章编号: N19090208
期刊: Organic Geochemistry
作者: Karen J. Wang, Jonathan A. O'Donnell, William M. Longo, Linda Amaral-Zettler, Gaoyuan Li, Yuan Yao, Yongsong Huang
更新时间: 2019-09-02
摘要: The Espenberg maar lakes on the Seward Peninsula, Alaska, are the largest volcanic crater lakes in the world and contain the longest known lacustrine sedimentary archives in Alaska. The lack of glacial-aged marine sedimentary archives around the Bering Land Bridge due to exposure of the shelf during sea level low-stands makes these lakes highly valuable for understanding the region’s past climate and environmental changes. Located en route to humanity’s last colonized American continents, the Seward Peninsula’s climate and environments during the last glacial period bear major anthropological significance. However, a lack of quantitative proxies has so far hampered exploration of these lakes for paleoclimate reconstructions. Here we report, for the first time, the discovery of abundant Group I alkenones and Isochrysidales in surface sediments from three maar lakes: White Fish, North Killeak and Devil Mountain, using a combination of lipid biomarker and 18S rRNA gene sequencing analyses. Our discovery adds to the expanding list of oligotrophic freshwater lakes where Group I alkenones are found, and water chemistry data contribute to the understanding of the environmental controls on Group I Isochrysidales. Our results further confirm the use of the U37K index of Group I alkenones as a proxy for the mean temperature of the spring isotherm (MTSI) and RIK37 as a quantitative measurement for Isochrysidales group mixing. We also demonstrate the analytical challenges for analyzing alkenones in freshwater lakes and the effectiveness of eliminating coelution using silver thiolate chromatographic material (AgTCM).

17507. 题目: Occurrence of organic compounds in groundwater of Saudi Arabia
文章编号: N19090207
期刊: Environmental Monitoring and Assessment
作者: Abdulaziz S. Alquwaizany, Sulaiman M. Alfadul, Mujahid A. Khan, Abdulrahman I. Alabdulaaly
更新时间: 2019-09-02
摘要: The presence of organic compounds in drinking water is well recognized in many developing countries; however, the occurrence of organic contaminants in the groundwater of Saudi Arabia, which is the main source of drinking water in the country, is not well documented. A national comprehensive study was carried out to assess the occurrence of organic compounds in groundwater wells used for drinking water purpose, in different regions of Saudi Arabia. A total of 993 well water samples were collected from all 13 administrative regions of the kingdom. Samples were analyzed for a total of 131 organic compounds using the standard methods. The results indicated that total organic carbon values were in the range of 0.01 to 84.13 mg/L with an average weighted value of 12.61 mg/L. Organic compounds were detected in only 9 regions, with 19.84% of the samples containing organic compounds. Only 96 wells (9.67%) showed contents of organic compounds above the safe limits. Pesticides were not detected in any of the well water samples. Overall, organic compounds were found in only 197 out of 993 wells (19.84%) in the whole country. Most of the wells containing organic compounds were located in residential, industrial, and agriculture areas. Riyadh region and Eastern Province were found to have the most affected wells as compared to other regions. Several regions did not show any organic compounds in the well waters. It can be said that the problem of groundwater contamination with organic compounds in Saudi Arabia is not acute and is manageable at present. It is, however, recommended that a regular monitoring of drinking water wells of all regions should be carried out by the competent authorities for organic compounds to know any contamination if and when it happens. Preventing such contaminants from reaching drinking water sources and protecting drinking water well heads from such contaminants remains a priority.

17508. 题目: New insight into the impact of biochar during vermi-stabilization of divergent biowastes: Literature synthesis and research pursuits
文章编号: N19090206
期刊: Chemosphere
作者: Muhammad Bilal Khan, Xiaoqiang Cui, Ghulam Jilani, Lin Tang, Min Lu, Xuerui Cao, Zulfiqar Ali Sahito, Yasir Hamid, Bilal Hussain, Xiaoe Yang, Zhenli He
更新时间: 2019-09-02
摘要: Biochar amendment for compost stabilization of divergent biowastes is gaining considerable attention due to environmental, agronomic and economic benefits. Research to date exhibits its favorable physico-chemical characteristics, viz. greater porosity, surface area, amount of functional groups, and cation exchange capacity (CEC), which allow interface with main nutrient cycles, favor microbial activities during composting, and improve the reproduction of earthworms during vermicomposting. Biochar amendment during composting and vermicomposting of biowastes boosts physico-chemical properties of compost mixture, microbial activities and organic matter degradation; and reduces nitrogen loss and emission of greenhouse gases (GHGs). It also improves the quality of final compost by increasing concentration of plant available nutrients, enhancing maturity, decreasing composting duration and reducing the toxicity of compost. Due to these characteristics, biochar could be considered a beneficial additive for the stabilization of different biowastes during composting and vermicomposting processes. Hence, good quality vermicompost, efficient recycling and management of biowastes could be achieved by addition of biochar through composting and vermicomposting.
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17509. 题目: PFOA and PFOS removal by ion exchange for water reuse and drinking applications: Role of organic matter characteristics
文章编号: N19090205
期刊: Environmental Science: Water Research & Technology
作者: Fuhar Dixit, Madjid Mohseni, Benoit Barbeau, Shadan Ghavam Mostafavi
更新时间: 2019-09-02
摘要: Perfluoroalkyl substances (PFAS) are drinking water contaminants of emerging concern due to their persistence in the environment and tendency to bio-accumulate. Although anionic ion exchange (IX) resins offer a cost-effective alternative for removing PFAS from natural waters, the studies on PFAS removal by IX under the influence of variable characteristics of the organic compounds present in the natural water sources, have been overlooked. This is critically important given that the organic matter (OM) characteristics are spatially variable and can change seasonally. In the present study, a strongly basic anion exchange resin was used to remove two of the most persistent PFAS, namely Per-fluorooctanoic acid (PFOA) and Per-fluorooctanesulfonic acid (PFOS). Factors influencing the uptake behavior included the PFOA and PFOS concentrations, resin dosage, and background OM characteristics, more specifically the charge density and molecular weight distribution of source water OM. The equivalent background concentration (EBC) was employed to evaluate the competitive uptake between OM and PFAS. Experimental data were fitted to different mathematical and physical models to evaluate the competitive interactions. Further, IX was able to achieve complete PFAS removal with simultaneous >60% Dissolved Organic Carbon (DOC) removal. Evidences of size exclusion and pore blockage were also observed in the presence of humics and larger molecular weight organic fractions. Results of this study indicate that IX exhibits great potential for simultaneous OM and PFAS removal for drinking and potable water reuse applications.

17510. 题目: Hydrothermal synthesizing sludge-based magnetite catalyst from ferric sludge and biosolids: Formation mechanism and catalytic performance
文章编号: N19090204
期刊: Science of The Total Environment
作者: He Zhang, Gang Xue, Hong Chen, Xiang Li
更新时间: 2019-09-02
摘要: Sludge-based magnetite catalyst (SBMC) containing Fe3O4 was synthesized by hydrothermal (HT) of biosolids and ferric sludge, which is a promising wasted sludge recycling way. The protein and carbohydrate, main representative compounds in biosolids, were used to explore the SBMC formation mechanism. A part of carbohydrate and the produced Maillard reaction products (MRPs) derived from two substrates via Maillard reaction (MR) were confirmed to participate in Fe3+ reduction. The MR accompanied by substrates humification, making MRPs own strong chelation activity. The MRPs (50–100 kDa) reflected the strongest relative reducing and chelation activity, mainly involving in Fe3O4 synthesis. Furthermore, the SBMC was verified as an efficient Fenton-like catalyst for aniline with 77.9% removal efficiency. The OH and O2 both contributed to the degradation, differing from only OH playing function in traditional Fenton-like system, implying biochar in SBMC could mediate the reactive oxygen species generating by Fe3O4, and benefit its catalytic performance.
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17511. 题目: Application of Simplicillium chinense for Cd and Pb biosorption and enhancing heavy metal phytoremediation of soils
文章编号: N19090203
期刊: Science of The Total Environment
作者: Zhongmin Jin, Songqiang Deng, Yuchen Wen, Yifeng Jin, Lin Pan, Yanfu Zhang, Tom Black, Kevin C. Jones, Hao Zhang, Dayi Zhang
更新时间: 2019-09-02
摘要: Phytoremediation is an effective approach to control soil heavy metal pollution. This study isolated a fungus strain from soils contaminated by cadmium (Cd) and lead (Pb) in Zhalong Wetland (China), which was identified as Simplicillium chinense QD10 via both genotypic and phenotypic analysis. The performance and mechanism of S. chinense QD10 in Cd and Pb adsorption was unraveled by morphological analysis and biosorption test, and its roles in ameliorating phytoremediation by Phragmites communis were tested in pot-experiments. Cd biosorption was attributed to the formation of Cd-chelate, whereas Pb was predominantly adsorbed by extracellular polymeric substances. Metal biosorption followed Langmuir isotherm, and the maximum biosorption capacity was 88.5 and 57.8 g/kg for Cd and Pb, respectively. Colonized in soils, such biosorption behavior of S. chinense QD10 can generate gradients of available Cr or Pb and drive their enrichment. Accordingly, S. chinense QD10 amendment significantly enhanced the phytoextraction of Cd and Pb by P. communis, possibly attributing to rhizospheric enrichment of Cd or Pb and defending effects on plants, explained by the significant removal of acid-extractable and reducible metals in soils and the increase of Cd and Pb content in P. communis tissues. The present study explored the mechanisms of S. chinense QD10 in Cd and Pb biosorption and proved its potential in ameliorating the phytoremediation performance at metal contaminated sites.
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17512. 题目: Biochar with near-neutral pH reduces ammonia volatilization and improves plant growth in a soil-plant system: A closed chamber experiment
文章编号: N19090202
期刊: Science of The Total Environment
作者: Sanchita Mandal, Erica Donner, Euan Smith, Binoy Sarkar, Enzo Lombi
更新时间: 2019-09-02
摘要: Ammonia (NH3) volatilization is considered as one of the major mechanisms responsible for the loss of nitrogen (N) from soil-plant systems worldwide. This study investigated the effect of biochar amendment to a calcareous soil (pH 7.8) on NH3 volatilization and plant N uptake. In particular, the effect of biochar's feedstock and application rate on both NH3 volatilization and plant growth were quantified using a specially designed closed chamber system. Two well-characterized biochars prepared from poultry manure (PM-BC) and green waste compost (GW-BC) were applied to the soil (0, 0.5, 1, 1.5 and 2% w/w equivalent to 0, 7.5, 15, 22 and 30 t ha−1) and wheat (Triticum aestivum, variety: Calingiri) was grown for 30 days. Both PM-BC and GW-BC decreased NH3 volatilization to a similar degree (by 47 and 38%, respectively), in the soil-plant system compared to the unamended control. Higher plant biomass production of up to 70% was obtained in the closed chamber systems with the addition of biochar. The increase in plant biomass was due to the reduction in N loss as NH3 gas, thereby increasing the N supply to the plants. Plant N uptake was improved by as much as 58% with biochar addition when additional NPK nutrients were supplied to the soil. This study demonstrates that the application of biochars can mitigate NH3 emission from calcareous agricultural cropping soil and that the retained N is plant-available and can improve wheat biomass yield.
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17513. 题目: Chloramination of iodide-containing waters: Formation of iodinated disinfection byproducts and toxicity correlation with total organic halides of treated waters
文章编号: N19090201
期刊: Science of The Total Environment
作者: Mahmut S. Ersan, Chao Liu, Gary Amy, Michael J. Plewa, Elizabeth D. Wagner, Tanju Karanfil
更新时间: 2019-09-02
摘要: The formation of iodinated disinfection byproducts (I-DBPs) in drinking waters is of a concern due to their higher cyto- and genotoxicity than their chlorinated and brominated analogues. This study investigated the formation of I-DBPs under chloramination conditions using preformed chloramine and associated cyto- and geno-toxicities obtained with Chinese Hamster Ovary (CHO) cell assay. Cyto- and geno-toxicity of the samples were also calculated using DBP toxicity index values and correlated with total organic halide (TOX) formation. In low iodide (I-) (0.32 μM, 40 μg L−1) water, increasing dissolved organic carbon (DOC) concentration of selected waters from 0.1 to 0.25 mg L−1 increased the formation of iodinated trihalomethanes (I-THMs), while further increases from 0.25 to 4 mg L−1 produced an opposite trend. In high iodide water (3.2 μM, 400 μg L−1), increasing DOC from 0.5 to 4 mg L−1 gradually increased the I-THM formation, while a decrease was observed at 5.4 mg L−1 DOC. Iodoform was the most influenced species from the changes in DOC concentration. While increasing the initial iodide concentration from 0 to 5 μM increased the formation of iodoform, it did not make any considerable impact on the formation of other I-THMs. The measured cytotoxicity of samples was significantly correlated with increasing DOC concentration. Unknown TOCl and TOI showed a high correlation with measured cytotoxicity, while calculated total organic chlorine (TOCl) and total organic iodine (TOI) did not correlate. The comparison of measured and calculated cytotoxicity values showed that the calculated values do not always represent the overall cytotoxicity, since the formation of unknown DBPs are not taken into consideration during the toxicity calculations.
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17514. 题目: Biowaste to treasure: Application of microbial-aged hydrochar in rice paddy could improve nitrogen use efficiency and rice grain free amino acids
文章编号: N19090113
期刊: Journal of Cleaner Production
作者: Shan Yu, Yanfang Feng, Lihong Xue, Haijun Sun, Lanfang Han, Linzhang Yang, Qingye Sun, Qingnan Chu
更新时间: 2019-09-01
摘要: Hydrochar is produced under hydrothermal carbonization, which can be considered as a cleaner process for black carbon production. Hydrochar shows good prospects in agro-environmental applications, but it is recommended to be ameliorated before application to improve its surface characteristics and reduce potential side-effects. This study, for the first time, proposed ameliorating poplar sawdust hydrochar via a microbial-aging process and applying it to rice paddy soil. In a soil-column experiment, sawdust hydrochar (SHC), microbial-aged SHC (M-SHC), and water-washed SHC (W-SHC) were added at different rates to examine their effects on rice growth and nitrogen usage efficiency (NUE). Additionally, the effects of hydrochar application on rice grain free amino acids (FAAs) were investigated. The study revealed that M-SHC had a positive effect on rice growth and increased the grain yield by 17.13%–22.99% compared with control. The NUE was also improved by M-SHC treatment. The positive effect of M-SHC on rice yield might be attributed to the reduced toxic biochar-derived dissolved organic matters, increased specific surface area, elevated hydrochar pH, and more nutrients released due to the microbial-aging process. Moreover, under M-SHC treatment, all 17 FAAs of grain were significantly higher than the control, by 46.26%. Both microbial-aging and water-washing amelioration of hydrochar had a positive effect on rice yield and FAAs, with the former exhibiting better prospects for application. This study will provide a new direction for cleaner recycling and utilization of biowaste.

17515. 题目: Antimony speciation and mobility during Fe(II)-induced transformation of humic acid-antimony(V)-iron(III) coprecipitates
文章编号: N19090112
期刊: Environmental Pollution
作者: Niloofar Karimian, Edward D. Burton, Scott G. Johnston
更新时间: 2019-09-01
摘要: Antimony, as the Sb(V) species, often occurs in oxic soils and sediments as coprecipitates with poorly-crystalline Fe(III)-bearing minerals. It is common for these Sb(V)-Fe(III) coprecipitates to also contain varying quantities of co-occurring humic acid (HA). When exposed to reducing conditions, the production of Fe(II) may cause the initial metastable HA-Sb(V)-Fe(III) phases to undergo rapid transformations to more stable phases, thereby potentially influencing the geochemical behavior of coprecipitated Sb(V). However, little is known about the impacts of this transformation on the mobility and speciation of Sb. In this study, we reacted synthetic HA-Sb(V)-Fe(III) coprecipitates (Fe:Sb ratio = 4, and C:Fe molar ratios = 0, 0.3, 0.8 and 1.3) with 0, 1 or 10 mM Fe(II) under O2-free conditions at pH 7.0 for 15 days. Fe K-edge EXAFS spectroscopy revealed that solid-phase Fe(III) in the initial coprecipitates contained a mixture of ∼4/5 ferrihydrite (Fe10O14(OH)2) and ∼1/5 tripuhyite (FeSbO4), regardless of the corresponding amount of coprecipitated HA. Tripuhyite persisted throughout the full experiment duration, while ferrihydrite was partially replaced by goethite (FeOOH) when either 1 or 10 mM Fe(II)aq was added to the coprecipitates. The greatest level of goethite formation (∼55% of solid-phase Fe) was observed in the HA-free/10 mM Fe(II)aq treatment, with ferrihydrite transformation being partially attenuated at higher levels of HA. Mobilisation of aqueous Sb was the greatest for 1 mM Fe(II) treatments at high HA:Fe ratios. Sb K-edge XANES spectroscopy showed that the largest reduction of Sb(V) to Sb(III) (∼37%) and the greatest repartitioning of Sb to the mineral surface (∼7.9–9.8%) occurred in the coprecipitates with the highest HA contents in the presence of 10 mM Fe(II). The results indicate that the amount of HA in HA-Sb(V)-Fe(III) coprecipitates can greatly influence mobility and speciation of Sb in Fe(II)-rich conditions. The results of this study provide new insights into alterations in Sb mobility and retention in response to Fe cycling under organic matter-rich reducing conditions.
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17516. 题目: Abiotic reduction of uranium(VI) with humic acid at mineral surfaces: Competing mechanisms, ligand and substituent effects, and electronic structure and vibrational properties
文章编号: N19090111
期刊: Environmental Pollution
作者: Qian Wang, Chang Zhu, Xiaoxiao Huang, Gang Yang
更新时间: 2019-09-01
摘要: Abiotic reduction represents an attractive technology to control U(VI) contamination. In this work, an abiotic route of U(VI) reduction with humic acid at mineral surfaces is proposed and reaction mechanisms are addressed by periodic density functional theory calculations. Different influencing factors such as ligand effect, content of CO32− ligands and substituent effect are inspected. The coordination chemistry of uranyl(VI) surface complexes relies strongly on substrates and ligands, and the calculated results are in good agreements with experimental observations available. For the OH ligand, two competitive mechanisms co-exist that respectively produce the U(IV) and U(V) species, and the former is significantly preferred because of lower energy barriers. Instead, the NO3 ligand leads to the formation of U(V) while for the Cl ligand, the U(VI) surface complex remains very stable and is not likely to be reduced because of very high energy barriers. The U(V) and U(IV) complexes are the predominant products for low and high CO32− contents, respectively. Accordingly, the abiotic reduction processes with humic acid are efficient to manage U(VI) contamination and become preferred under basic conditions or at higher CO32− contents. The U(VI) reduction is further promoted by introduction of electron-donating rather than electron-withdrawing substituents to humic acid. Electronic structure analyses and vibrational frequency assignments are calculated for the various uranium surface complexes of the reduction processes, serving as a guide for future experimental and engineered studies. The molecular-level understanding given in this work offers an abiotic route for efficient reduction of U(VI) and remediation of U(VI)-contaminated sites at ambient conditions.
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17517. 题目: Remediation of organic halogen- contaminated wetland soils using biochar
文章编号: N19090110
期刊: Science of The Total Environment
作者: Liqiang Cui, Chuntao Yin, Tianming Chen, Guixiang Quan, James A. Ippolito, Benzhi Liu, Jinlong Yan, Cheng Ding, Qaiser Hussain, Muhammad Umer
更新时间: 2019-09-01
摘要: Organochlorine waste from papermaking has polluted soils worldwide, and the addition of biochar will improve polluted soils in a variety of scenarios. A field study (2014 to 2016) was conducted to investigate the application of wheat (Triticum aestivum L.) straw biochar (0, 20, 40, 60 Mg ha−1) to organic halogen-contaminated saline-alkali soil. The addition of biochar reduced the concentrations of adsorbable organic halogens (AOX) in the soil and extractable organic halogens (EOX) in reeds (Phragmites communis) by 9–94% and 14%–51%, respectively, and subsequently increased reed biomass by 1%–25%; these changes were related to the changes in different soil properties. Soil properties, such as the organic functional groups, surface properties, and pH, were improved following the addition of biochar, and some changes were maintained at heightened levels over time. The activity of urease, alkaline phosphatase, and sucrase enzymes in soil increased by 14 to 57%, 2 to 147%, and 1 to 75% as a function of increasing biochar amendment, respectively, while that of dehydrogenase decreased by 13% to 60%, which may have aided in the acceleration of AOX decomposition. The diversity of the bacterial community also increased due to biochar application, and is likely a key indicator of halogen degradation. The addition of biochar likely decreased the bioavailability of organic halogens by improving the function and structure of the microbial community, reducing their transfer to reeds grown in papermaking organochlorine-contaminated soils. Biochar may play an important role in reducing environmental contamination by organic halogens.
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17518. 题目: Optical determination of black carbon mass concentrations in snow samples: A new analytical method
文章编号: N19090109
期刊: Science of The Total Environment
作者: Francisco Cereceda-Balic, Tamara Gorena, Camila Soto, Victor Vidal, Magín Lapuerta, Hans Moosmüller
更新时间: 2019-09-01
摘要: Black carbon (BC) aerosols in the atmosphere strongly affect direct radiative forcing and climate, not only while suspended in the atmosphere but also after deposition onto high albedo surfaces. Snow surfaces are especially sensitive to BC deposition, because of their high surface albedo and additional positive feedbacks further enhance faster snowpack melting caused by BC deposition, resulting in modifications in water resources and recession of glaciers. For the analysis of BC deposition on snow, a precise quantification of BC mass is needed. Instead, optical methods have the potential of quantifying only BC, based on its characteristic spectral absorption. Commercial optical transmissometers commonly use quartz filters to filter BC and measure its optical attenuation. They are calibrated for the determination of BC mass concentrations in air, but not adapted or calibrated for their determination in water or snowmelt samples. Additionally, they are generally calibrated using BC-simulating materials that are not representative of ambient BC particles.Here, a new analytical method is demonstrated for the quantitative determination of BC mass concentration in snow samples that considers filtering of melted snow with polycarbonate filters in a new device, and optical filter attenuation BC mass concentration measurement (880 nm). The attenuation can be obtained with any optical equipment that can measure the 880-nm attenuation of filters impacted with BC/snow impurities.This method has been calibrated using real diesel vehicle exhaust soot with well-known optical properties as reference material, yielding a multipoint calibration curve for common BC concentration levels in snow. The limits of detection (0.011 mg of BC), quantification (0.036 mg of BC) and reproducibility (96.39%) of this new analytical method have been determined. Real surface snow samples collected at different locations in “Los Andes” mountains of Chile were measured with this method given a BC concentrations ranged from 151 to 5987 μg kg−1.
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17519. 题目: Simulation of dissolved organic carbon concentrations and fluxes in Chinese monsoon forest ecosystems using a modified TRIPLEX-DOC model
文章编号: N19090108
期刊: Science of The Total Environment
作者: Shengwei Shi, Mingxia Yang, Yue Hou, Changhui Peng, Haibin Wu, Qiuan Zhu, Qiong Liang, Junfei Xie, Meng Wang
更新时间: 2019-09-01
摘要: Dissolved organic carbon (DOC) plays an important role in global and regional carbon cycles. However, the quantification of DOC in forest ecosystems remains uncertain. Here, the processed-based biogeochemical model TRIPLEX-DOC was modified by optimizing the function of soil organic carbon distribution with increasing depths, as well as DOC sorption-desorption efficiency. The model was validated by field measurements of DOC concentration and flux at five forest sites and Beijiang River basin in monsoon regions of China. Model validation indicated that seasonal patterns of DOC concentration across climatic zones were different, and these differences were captured by our model. Importantly, the modified model performed better than the original model. Indeed, model efficiency of the modified model increased from −0.78 to 0.19 for O horizon predictions, and from −0.46 to 0.42 for the mineral soils predictions. Likewise, DOC fluxes were better simulated by the modified model. At the site scale, the simulated DOC fluxes were strongly correlated with the observed values (R2 = 0.97, EF = 0.91). At the regional scale, the DOC flux predicted in the Beijiang River basin was 16.44 kg C/ha, which was close to the observed value of 17 kg C/ha. Using sensitivity analysis, we showed that temperature, precipitation and temperature sensitivity of DOC decomposition (Q10) were the most sensitive parameters when predicting DOC concentrations and fluxes in forest soils. We also found that both the percentage of DOC flux to forest net ecosystem productivity, and the retention of DOC by mineral soil were highly correlated with the amount of precipitation. Overall, our model validations indicated that the modified TRIPLEX-DOC model is a useful tool for simulating the dynamics of DOC concentrations and fluxes in forest ecosystems. We highlight that more accurate estimates of parameter Q10 in deep mineral soils can reduce model uncertainty, when simulating DOC concentrations and fluxes in forest soils.
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17520. 题目: Effect of metal-organic interactions on the oxidative potential of mixtures of atmospheric humic-like substances and copper/manganese as investigated by the dithiothreitol assay
文章编号: N19090107
期刊: Science of The Total Environment
作者: Manfei Lin, Jian Zhen Yu
更新时间: 2019-09-01
摘要: Excessive generation of reactive oxygen species (ROS) and the corresponding oxidative stress has been recognized as one important cause for the adverse health effects associated with exposure to ambient particulate matter (PM). Transition metals and humic-like substances (HULIS) in PM have been separately demonstrated to contribute to the oxidative potential (OP) of PM, however, only few studies investigated the impact of their interactions on the measured OP and the effect is little understood. HULIS is an abundant fraction of water-soluble organic material in PM and serves to represent real-world PM organics. In this study, we applied a cell-free dithiothreitol (DTT) assay to quantify the OP, termed as OPDTT, by two representative transition metals (i.e., copper (Cu) and manganese (Mn)), HULIS, and mixtures of HULIS and metals in concentration levels relevant to those in human lung fluid resulting from PM inhalation. The organic-metal mixture effect was found to be metal-specific and concentration-specific, covering the possibility spectrum from being synergistic, additive to antagonistic. HULIS was observed to suppress OPDTT up to 10–20% by Cu at a concentration of 0.08 μM while had no discernable effect at 0.5 μM Cu. On the contrary, obvious enhancement of OPDTT was recorded in the mixtures of HULIS and Mn (e.g. up to ~2 times at 2.5 μM of Mn) while no mixture effects could be discerned at 0.5 μM Mn. Our work demonstrates the need for considering the metal-organic interactions and the complexity when evaluating the total OP of their mixtures, such as ambient PM samples. Further work in metal-PM organics interactions should be conducted using methods capable of measuring specific oxidants, in addition to the ability to deplete the reducing agent (i.e., DTT), in order to acquire a deeper mechanistic insight into the interactions.
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