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13261. 题目: Enhanced As(III) removal from aqueous solution by Fe-Mn-La-impregnated biochar composites
文章编号: N19060306
期刊: Science of The Total Environment
作者: Lina Lin, Zhengguo Song, Zulqarnain Haider Khan, Xuewei Liu, Weiwen Qiu
更新时间: 2019-06-03
摘要: A novel Fe-Mn-La-impregnated biochar composite (FMLBC) was synthesized using an impregnation method for efficient As (III) adsorption. The pseudo-second-order model (R2 values are 0.996, 0.996, and 0.994 for different FMLBC rate used) better fitted the kinetic adsorption of As on the FMLBC than the pseudo-first order model (R2 values are 0.978, 0.971, and 0.991 respectively). The SEM-EDS, FTIR and XPS results confirmed the addition of Fe, Mn and La into the BC structure. Compared with pristine biochar (3.73 mg g−1) and Fe-Mn-impregnated biochar (9.48 mg g−1), the As (III) adsorption capacity of Fe-Mn-La impregnated biochar (14.9 mg g−1) was significantly improved. The presence of NO3 and SO42− did not influence arsenic adsorption, whereas PO43− influenced arsenic removal. The mechanism of arsenic adsorption on the FMLBC involved oxidization, electrostatic attraction, ligand exchange, and formation of an inner-sphere R-O-As complex. Among them, the electrostatic attraction and inner-sphere complexation contributed the most. The simple preparation process and high adsorption performance suggest that the FMLBC could serve be as a promising adsorbent for aqueous As (III) removal from aqueous solution.
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13262. 题目: Effects of combined biochar and organic fertilizer on nitrous oxide fluxes and the related nitrifier and denitrifier communities in a saline-alkali soil
文章编号: N19060305
期刊: Science of The Total Environment
作者: Yulong Shi, Xingren Liu, Qingwen Zhang
更新时间: 2019-06-03
摘要: This study intended to evaluate the combined effects of both biochar and organic fertilizer on nitrous oxide (N2O) fluxes and composition of nitrifier and denitrifier of saline-alkali soil. Therefore, four different treatments such as CK (only chemical fertilizer), B (only biochar), M (only organic fertilizer), BM (B:M = 1:1) were used in this experiment. The results showed that N2O emissions were decreased in B and BM treatments compare to the control. In contrast, N2O emissions were highest before day 12 but lowest after day 19 in M treatment compare to CK treatment. Application of biochar, organic fertilizer and biochar plus organic fertilizer decreased the nirS and nirK genes copies and enhanced the nosZ gene copies which resulting in the lower N2O fluxes. The ammonia-oxidizing bacteria (AOB) amoA and nirK genes copies were significantly increased by organic fertilizer before day 12, leading to high N2O emissions. The genera Nitrosospira (AOB) and Nitrososphaera (ammonia-oxidizing archaea, AOA) assumed absolute superiority. Additionally, Nitrosospira (AOB) was also appeared in nirK-type denitrifiers, illustrating denitrification was carried out by nitrifiers. The genera Azospirillum (nirS), Burkholderia (nosZ) and Polymorphum (nosZ) were dominant in CK. There was only one dominant genus, Mesorhizobium (nosZ) in the B treatment. The genera Mesorhizobium (nirK), Azoarcus (nirS), Kocuria (nirS) and Pseudomonas (nosZ) occupied the main status in the M treatment. The relative abundance of Rhodanobacter (nirS) and Azospirillum (nosZ) were higher in the BM treatment compared with other treatments. Soil water content (SWC), pH, NH4+-N and NO3-N were the main factors affecting AOB and denitrifiers, which influencing N2O emissions. Overall, combined application of biochar and organic fertilizer can reduce the N2O emission where AOB and nirK-type denitrifier were the main contributors to the N2O emission.
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13263. 题目: Temperature sensitivity of mineral-enzyme interactions on the hydrolysis of cellobiose and indican by β-glucosidase
文章编号: N19060304
期刊: Science of The Total Environment
作者: Ziming Yang, Yiju Liao, Xuan Fu, Jared Zaporski, Stephanie Peters, Megan Jamison, Yurong Liu, Stan D. Wullschleger, David E. Graham, Baohua Gu
更新时间: 2019-06-03
摘要: Extracellular enzymes are mainly responsible for depolymerizing soil organic matter (SOM) in terrestrial ecosystems, and soil minerals are known to affect enzyme activity. However, the mechanisms and the effects of mineral-enzyme interactions on enzymatic degradation of organic matter remain poorly understood. In this study, we examined the adsorption of fungal β-glucosidase enzyme on minerals and time-dependent changes of enzymatic reactivity, measured by the degradation of two organic substrates (i.e., cellobiose and indican) under both cold (4 °C) and warm (20 and 30 °C) conditions. Hematite, kaolinite, and montmorillonite were used, representing three common soil minerals with distinctly different surface charges and characteristics. β-glucosidase was found to sorb stronger onto hematite and kaolinite than montmorillonite. All three minerals inhibited enzyme degradation of cellobiose and indican, likely due to the inactivation or hindrance of enzyme active sites. The mineral-bound β-glucosidase retained its specificity for organic substrate degradation, and increasing temperature from 4 to 30 °C enhanced the degradation rates by 2–4 fold for indican and 5–9 fold for cellobiose. These results indicate that enzyme adsorption, mineral type, temperature, and organic substrate specificity are important factors influencing enzymatic reactivity and thus have important implications in further understanding and modeling complex enzyme-facilitated SOM transformations in terrestrial ecosystems.
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13264. 题目: Identifying a quick and efficient method of removing organic matter without damaging microplastic samples
文章编号: N19060303
期刊: Science of The Total Environment
作者: Joana C. Prata, João P. da Costa, Ana V. Girão, Isabel Lopes, Armando C. Duarte, Teresa Rocha-Santos
更新时间: 2019-06-03
摘要: Natural organic matter may confound the detection of microplastics, requiring a removal step. However, most available protocols are long and lack information on removal efficiency and polymer degradation. Thus, we have determined the digestion efficiency (%) for a pool of organic matter (algae, driftwood, feathers, fish muscle, paraffin, palm oil) for five digestion solutions, hydrogen peroxide (H2O2), hydrogen peroxide with iron catalyst (H2O2 + Fe), potassium hydroxide (KOH), nitric acid (HNO3), and sodium dodecyl sulphate (SDS), under two temperatures (room temperature at 25 °C, 50 °C) and two periods (1, 6 h). H2O2 + Fe and KOH at 50 °C for 1 h had the highest digestion efficiencies, of 65.9% and 58.3% respectively (mostly limited by driftwood and paraffin). Further testing revealed that H2O2 + Fe is more appropriate for plant material and KOH for animal tissue. Weight loss (%), Fourier transform infrared spectrometry and carbonyl index of 9 virgin and 6 weathered polymers (polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polyvinyl chloride, cellulose acetate, nylon) revealed that only identification of cellulose acetate was hindered. Filters were also tested revealing that quartz and glass fibre filters are resistant to these protocols. Thus, a digestion protocol based on H2O2 + Fe or KOH at 50 °C for 1 h may be used on microplastic samples.
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13265. 题目: Effects of depositional environment and organic matter degradation on the enrichment and mobilization of iodine in the groundwater of the North China Plain
文章编号: N19060302
期刊: Science of The Total Environment
作者: Xiaobin Xue, Junxia Li, Xianjun Xie, Yanxin Wang, Xiaowei Tian, Xiucheng Chi, Yuting Wang
更新时间: 2019-06-03
摘要: Groundwater iodine has direct importance for human dietary iodine intake in areas where drinking water is of groundwater origin. However, little is known about enrichment and mobilization mechanisms of groundwater iodine in the North China Plain (NCP). Geochemistry, inorganic/organic carbon isotope and biomarker of groundwater and sediment samples were studied to reveal the effects of depositional environment and organic matter (OM) degradation on the generation of high iodine groundwater (>100 μg/L) in NCP. Results showed that groundwater iodine had a range of 7.2–800 μg/L and was increasing with increase in HCO3 concentration and decrease in groundwater δ13CDIC value, indicating the potential effects of microbial activity on the elevation of groundwater iodine. Sediments iodine ranged from 0.03 to 2.54 μg/g and higher contents occurred under the oxidizing depositional environment (higher Pr/Ph ratios). Biomarker analysis indicated that the marine iodine-rich OM is considered as the main source of groundwater iodine, which is prone to be released into groundwater by the microbial degradation under the reducing conditions. The hypothesis was evidenced by the 13Corg, 13CDIC and 3-D excitation emission matrices of groundwater. These results suggest that carbon-related biogeochemical cycling and redox condition are important in the enrichment and mobilization of iodine in groundwater system.
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13266. 题目: Co-transport of U(VI) and gibbsite colloid in saturated granite particle column: Role of pH, U(VI) concentration and humic acid
文章编号: N19060301
期刊: Science of The Total Environment
作者: Junwei Yang, Zhen Zhang, Zongyuan Chen, Mengtuan Ge, Wangsuo Wu, Zhijun Guo
更新时间: 2019-06-03
摘要: Understanding the in-situ transport behavior of U(VI) in granitic formations is of considerable interest for geological disposal of high-level radioactive wastes (HLW). In this context, the co-transport of U(VI) and representative naturally-occurring colloids, i.e., humic acid (HA) and gibbsite colloid (GC), was studied in granite column as a function of pH, U(VI) concentration and HA amount. It was found that, in addition to pH, co-transport of U(VI) and GC was also controlled by U(VI) concentration, the effect of which can be transport-facilitating and transport-impeding for U(VI) at relatively low concentration (2.0 × 10−6 mol/L) and for U(VI) at high concentration (5.0 × 10−5 mol/L), respectively. HA can present opposite effects on GC transport depending on HA amount. The transport-impeding effect by small amount of HA (5 mg/L) is due to strong aggregation between GC and HA from electrostatic attraction and complexation, whereas the transport-facilitating effect by big amount of HA (20 mg/L) is because of the complete HA coating which stabilizes associated colloids and alters surface charge from positive to negative. In ternary co-transport systems, a similar HA-dependent effect was also observed for both U(VI) and GC regardless of presence of high concentration U(VI). Besides the application of the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory, the mechanisms behind binary and ternary co-transport of U(VI), GC and HA were also analyzed by assessing the evolutions of zeta potential and particle size in the column effluents. Finally, a two-site non-equilibrium model and a two-site kinetic attachment/detachment model were applied to describe the breakthrough curves of U(VI) and individual/combined colloids, respectively. The findings of this study indicated that combined effects of GC and HA on radionuclides transport is dominated by the amount of HA, and a facilitating transport of radionuclide can be expected in the underground environment rich in humic acid.
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13267. 题目: Formation of disinfection byproducts as affected by biochar during water treatment
文章编号: N19060203
期刊: Chemosphere
作者: Min Zhang, Xuan Wang, Huizhi Hao, Huihui Wang, Lin Duan, Yao Li
更新时间: 2019-06-02
摘要: Biochar (BC) is as an emerging and promising adsorbent for the removal of pollutants from aqueous solutions in water treatment given its porous structure, large surface area, and numerous O-functional groups. However, the effects of BC on the formation of disinfection byproducts (DBPs) during the disinfection process of water treatment remains largely unknown. This study investigated the influence of aqueous solution chemistry on DBP formation in the presence of BC during chlorination. BC samples prepared from different biomass precursors (wheat straw, peanut shells, and shaddock peel) with different pyrolysis temperatures were compared, and the effects of aqueous solution chemistry were systematically investigated. Results indicated that DBPs could be formed during disinfection with BC. Certain intermediate DBP products would undergo base catalysis to form trichloromethane (TCM) via hydrolysis as pH increased. This phenomenon would increase TCM content, as well as decrease chloral hydrate and 1,1-dichloro-2-propanone content. The increment in inorganic ion (NaCl) content showed negligible effects on DBP formation during BC chlorination. DBP formation was restrained in the presence of humic acid (HA) because the number of active sites on BC that participated in the reaction decreased when BC adsorbed HA.

13268. 题目: Effects of natural organic matters on bioavailability of petroleum hydrocarbons in soil-water environments
文章编号: N19060202
期刊: Chemosphere
作者: Chih-Hung Chen, Pao-Wen Grace Liu, Liang-Ming Whang
更新时间: 2019-06-02
摘要: The bioremediation efficiency of petroleum hydrocarbons in natural soil-water systems is regulated by active microbial populations and other system parameters. Relevant factors include the transfer rate of petroleum contaminants from a medium into microorganisms, the partitioning behavior of contaminants from water into the soil organic matter (SOM), and the influence of the dissolved organic matter (DOM) on the contaminant level in water. The objectives of this study was aimed to determine the correlation among bioavailability of petroleum hydrocarbons, SOM content, and DOM level in soil-water systems. Heptadecane, pristane, and decylcyclohexane were selected as model hydrocarbon contaminants. The bioavailability of target contaminants in soil was examined using soils of different SOM contents (2% and 20%) in slurry bioreactors. In addition, the contaminant bioavailability as affected by various DOM levels (0–100 mgC/L) was also examined. The results showed that the SOM content affected the degrading rate of hydrocarbons significantly, where the rate constant was 4 times higher in 2% SOM microcosm than in the 20% SOM bioreactor for heptadecane degradation. Similarly, the pristane degrading efficiency after 240 h operation was 95% for the 2% SOM microcosm and only 38% for the 20% SOM microcosm. The hydrocarbon degradation rates in water phase were found to be enhanced by the added DOM level. A positive correlation existed between the contaminant bioavailability and the contaminant level in water as impacted by the SOM content in soil and the DOM level in water.

13269. 题目: Sorption of PFOS isomers on goethite as a function of pH, dissolved organic matter (humic and fulvic acid) and sulfate
文章编号: N19060201
期刊: Chemosphere
作者: Jean-Noel Uwayezu, Leo W.Y. Yeung, Mattias Bäckström
更新时间: 2019-06-02
摘要: Understanding the distribution of PFOS isomers between the aqueous phase and goethite is crucial, since it is an abundant sorbent and thus may have a large influence on the mobility of PFOS. This study was conducted to understand the effects of pH, humic acid (HA), fulvic acid (FA) and sulfate on sorption of PFOS isomers. The results will increase the understanding about what parameters may control the fate and transport of PFOS in surface and ground water.The study was conducted by adding PFOS spiked water to a goethite slurry in different aqueous chemistry. Levels of total and PFOS isomers were quantified using an Ultra-Performance Liquid chromatograph coupled to a triple quadrupole mass spectrometer. Results showed that sorption of PFOS was mainly dependent on pH; sorption decreased as pH increased. Presence of HA increased log Kd from 1.29 to 2.03, 1.76 to 1.92 and 1.51 to 1.96 at pH 5.50–7.50 for 3-/4-/4-PFOS, 6-/2-PFOS and L-PFOS, respectively. Changes in the aqueous chemistry also affected the behavior of PFOS as the addition of Na2SO4 enhanced the sorption of PFOS. Results showed that L-PFOS was more readily sorbed to goethite at pH < 4.35 both in the presence and in the absence of humic or fulvic acids. At pH > 4.5 the 3-/4-/5-PFOS isomer group was more associated to the solid phase. Besides electrostatic interactions, which controlled the sorption of PFOS, this study indicate that the presence of dissolved humic substances in the aqueous phase enhances the sorption via hydrophobic mechanisms.

13270. 题目: Photochemical Transformations of Dichloroacetamide Safeners
文章编号: N19060109
期刊: Environmental Science & Technology
作者: Andrew E. Kral, Nicholas C. Pflug, Monica E. McFadden, Gregory H. LeFevre, John D. Sivey, David M. Cwiertny
更新时间: 2019-06-01
摘要: Dichloroacetamide safeners are commonly added to commercial chloroacetamide herbicide formulations and widely used worldwide, but their environmental fate has garnered little scrutiny as a result of their classification as inert ingredients. Here, we investigated the photolysis of dichloroacetamide safeners to better understand their persistence and the nature of their transformation products in surface waters. High-resolution mass spectrometry (HRMS) and nuclear magnetic resonance (NMR) spectroscopy were used to characterize photoproducts. Of the four commonly used dichloroacetamide safeners, only benoxacor undergoes direct photolysis under simulated natural sunlight (t1/2 ∼ 10 min). Via a photoinitiated ring closure, benoxacor initially yields a monochlorinated intermediate that degrades over longer irradiation time scales to produce two fully dechlorinated diastereomers and a tautomer, which further photodegrade over several days to a structurally related aldehyde confirmed via NMR. Dichlormid, AD-67, and furilazole were more slowly degraded by indirect photolysis in the presence of the photosensitizers nitrate, nitrite, and humic acid. Reactive entities involved in these reactions are likely hydroxyl radical and singlet oxygen based on the use of selective quenchers. These safeners also directly photolyzed under higher energy ultraviolet (UV) light, suggesting their potential transformation in engineered systems using UV for disinfection. The finding that dichloroacetamide safeners can undergo photolysis in environmental systems over relevant time scales demonstrates the importance of evaluating the fate of this class of inert agrochemicals.

13271. 题目: Oxygen isotopes (δ18O) trace photochemical hydrocarbon oxidation at the sea surface
文章编号: N19060108
期刊: Geophysical Research Letters
作者: Collin P. Ward, Charles M. Sharpless, David L. Valentine, Christoph Aeppli, Kevin M. Sutherland, Scott D. Wankel, Christopher M. Reddy
更新时间: 2019-06-01
摘要: Although photochemical oxidation is an environmental process that drives organic carbon (OC) cycling, its quantitative detection remains analytically challenging. Here, we use samples from the Deepwater Horizon oil spill to test the hypothesis that the stable oxygen isotope composition of oil (δ18OOil) is a sensitive marker for photochemical oxidation. In less than one‐week, δ18OOil increased from ‐0.6 to 7.2‰, a shift representing ~25% of the δ18OOC dynamic range observed in nature. By accounting for different oxygen sources (H2O or O2) and kinetic isotopic fractionation of photochemically incorporated O2, which was ‐9‰ for a wide range of OC sources, a mass balance was established for the surface oil's elemental oxygen content and δ18O. This δ18O‐based approach provides novel insights into the sources and pathways of hydrocarbon photo‐oxidation, thereby improving our understanding of the fate and transport of petroleum hydrocarbons in sunlit waters, and our capacity to respond effectively to future spills.

13272. 题目: TEMPORAL VARIABILITY OF SOIL ORGANIC CARBON IN PADDIES DURING 13‐YEAR CONSERVATION TILLAGE
文章编号: N19060107
期刊: Land Degradation & Development
作者: Jian‐Ying Qi, Xing Wang, Xin Zhao, Chao Pu, Zheng‐Rong Kan, Chao Li, Peng Liu, Xiao‐Ping Xiao, Rattan Lal, Hai‐Lin Zhang
更新时间: 2019-06-01
摘要: Decreasing temporal variability of soil organic carbon (SOC) can avoid its temporary loss, which is positive to SOC accumulation and mitigation of climate change. Thus, this study was designed to analyze the temporal variability of SOC stock during 13‐year tillage practices and its driving factors in rice paddies of Southern China. Four tillage practices were studied: no‐till with residues retained on the soil surface (NTS, conservation tillage), rotary tillage with incorporated residues (RTS), moldboard plow tillage with incorporated residues (CTS) or with residues removed (CT). The SOC stock at 0‐30 cm soil depth varied widely between 2007 and 2017, partly due to the annual temperature and precipitation variations. The temporal variation of SOC was lower under NTS than other tillage practices (p<0.05). This was associated with the lower variation of heavy SOC and mineral associated SOC, as well as with lower (p<0.05) potential mineralizable carbon under NTS. Despite SOC saturated in all treatments, NTS increased (p<0.05) the SOC content by 12.1‐35.3% at 0‐5 cm soil depth. Thus, NTS in double rice paddies has been proved to be a promising option to maintain high levels of soil C accumulation with low temporal variability, especially at the upper 0‐5 cm depth.

13273. 题目: Investigating the binding properties between antimony(V) and dissolved organic matter (DOM) under different pH conditions during the soil sorption process using fluorescence and FTIR spectroscopy
文章编号: N19060106
期刊: Ecotoxicology and Environmental Safety
作者: Yurui Fan, Chunli Zheng, Aidi Huo, Qiaorui Wang, Zhenxing Shen, Zhiwei Xue, Chi He
更新时间: 2019-06-01
摘要: Antimony (Sb) is listed as a priority pollutant by European Union and U.S. Environmental Protection Agency. However, reports on its environmental behavior, particularly the sorption process in soil are still limited. In this paper, Sb(V) was selected as the sorbate and the black soil as the sorbent. The initial sorption rate (k2qe,cal2) was calculated to be 0.1254 mg g−1∙min−1 and the maximum sorption amount (qm) 57.33 mg g−1. Once the dissolved organic matter (DOM) was removed from the soil, the values of k2qe,cal2 and qm went down to 0.1066 mg g−1∙min−1 and 19.01 mg g−1, respectively. These results suggested that the existence of DOM significantly influenced the mass transfer rate and sorption amount of Sb(V) in soil. In order to find out the reason why DOM exerted such an influence, the binding interaction mechanism between Sb(V) and DOM was investigated under different pH values. The protein-like and humic-like substances as well as the functional groups of CO, phenol hydroxyl, C–O, C–H, C-X and sulfur/phosphorus contributed to the formation of DOM-Sb(V)-complexes under pH of 7.0, in which the humic-like substance and the functional groups containing oxygen showed higher binding affinity for Sb(V) than protein-like substance and other functional groups, respectively. The protein-like substance and some functional groups disappeared under pH of 4.0 and 10.0. Alkaline condition resulted in a bigger impact on reducing the number of functional groups than acid condition. It can be concluded that the strongest binding interaction occurred at pH of 7.0 then followed by 4.0 and 10.0. This paper might be helpful to further studying the environmental behavior of Sb(V) in soil.
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13274. 题目: Methylmercury production in a paddy soil and its uptake by rice plants as affected by different geochemical mercury pools
文章编号: N19060105
期刊: Environment International
作者: Jinling Liu, Jianxu Wang, Yongqiang Ning, Shaochen Yang, Pengcong Wang, Sabry M. Shaheen, Xinbin Feng, Jörg Rinklebe
更新时间: 2019-06-01
摘要: The formation of neurotoxic methylmercury (MeHg) in paddy fields and its accumulation by rice plants is of high environmental concern. The contribution of different geochemical mercury (Hg) pools in paddy soils to MeHg production and its accumulation by rice seedlings is not well-studied up to now. Therefore, we investigated the impact of different inorganic Hg forms, including HgCl2, nano-particulated HgS (nano-HgS), Hg bound with dissolved organic matter (Hg-DOM), β-HgS, and α-HgS, at levels of 5 mg Hg/kg soil and 50 mg Hg/kg soil, on the production of MeHg in the soil during rice growing season. Further, we studied the uptake of MeHg by the roots, stalks, leaves, and grains of rice in the tillering, panicle formation, and ripening growth stages, and compared these treatments to a non-polluted soil (control). MeHg contents in HgCl2 polluted soil were the highest, and were 13.5 times and 36.1 times higher than control in 5 and 50 mg/kg Hg treatments, respectively. MeHg contents in α-HgS, β-HgS, nano-HgS, and Hg-DOM polluted soil were 3.9, 2.6, 2.4, and 1.7 times, and 4.4, 15.1, 6.7, and 10.9 times higher than control in 5 and 50 mg/kg Hg treatments, respectively, suggesting the mobilization and methylation of these Hg complexes. The ratio of MeHg to total Hg in the pore water (indication of methylation potential) in HgCl2 and β-HgS treatments were higher than in Hg-DOM, α-HgS, and nano-HgS treatments. HgCl2 treatment resulted in significantly higher MeHg contents in the root, stalk, leaf, and brown rice than nano-HgS, Hg-DOM, β-HgS, and α-HgS treatments both in 5 and 50 mg/kg Hg polluted soils. Rice grain in HgCl2 treatment showed a potential hazard to human health, as indicated by high health risk index (HRI > 1) of MeHg. Current results improve our understanding of MeHg production in soil polluted with different Hg forms, and the assessment of human health risks from consumption of MeHg-laden rice grain at Hg polluted sites with different Hg forms in soils.

13275. 题目: Metal pollution in surface sediments from Rodrigo de Freitas Lagoon (Rio de Janeiro, Brazil): Toxic effects on marine organisms
文章编号: N19060104
期刊: Environmental Pollution
作者: Mariana Vezzone, Ricardo Cesar, Denis Moledo de Souza Abessa, Aline Serrano, Rodrigo Lourenço, Zuleica Castilhos, Ana Paula Rodrigues, Fernando Cesar Perina, Helena Polivanov
更新时间: 2019-06-01
摘要: The Rodrigo de Freitas Lagoon (RFL - Rio de Janeiro, RJ, Brazil) is a highly polluted and eutrophic lacustrine system, which has been often used for the practice of aquatic sports, including during the 2016 Summer Olympic Games. This study proposes the evaluation of metal concentrations in surface sediments from the RFL before and after urban interventions performed for the 2016 Olympics, as well as their toxicity to the benthic amphipod Tiburonella viscana and embryos of the sea-urchin Echinometra lucunter. Metal concentrations determined in 2017 were significantly higher than those obtained in 2015 (especially Cu, Cd and Ni), suggesting that the interventions performed to fulfill the requirements of the Olympics increased metal contents in sediments. The sediments from the northern sector of the RFL were muddier, more organically enriched, exhibited higher metal concentrations and were more toxic to T. viscana when compared to the sediments collected in the southern sector. This fact is particularly important since the practice of sports, including during the 2016 Olympics, has been preferably performed in the northern sector. Metal distribution was strongly correlated with organic matter and mud contents. The toxicity to E. lucunter embryos was high for both northern and southern sediments; most of the samples led to 100% lack or abnormal embryonic development. The integration of physical, chemical and ecotoxicological data indicates that the mortality to T. viscana was correlated with metal contents, whereas the toxicity to E. lucunter was apparently related to the release of ammonia from the sediment to water column. Finally, high metal concentrations and the toxicity to aquatic organisms evidence the ecological risks to the biota from RFL.
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13276. 题目: Initial microaggregate formation: Association of microorganisms to montmorillonite-goethite aggregates under wetting and drying cycles
文章编号: N19060103
期刊: Geoderma
作者: Lars Krause, Danh Biesgen, Aaron Treder, Steffen A. Schweizer, Erwin Klumpp, Claudia Knief, Nina Siebers
更新时间: 2019-06-01
摘要: There is an intimate relationship between microorganisms and the formation and stability of soil microaggregates, realized by the immobilization and occlusion of microorganisms. Little is known about the initial aggregate formation phase and the role of microorganisms in this process under the impact of environmental changes such as wetting and drying. We investigated this initial aggregate formation process of montmorillonite and goethite in combination with two bacterial strains, Pseudomonas protegens strain CHA0 and Gordonia alkanivorans strain MoAcy 2, in the presence or absence of stress conditions in form of wetting and drying cycles for up to eight days. Montmorillonite and goethite formed microaggregates instantaneously, the size of these aggregates being enhanced in the presence of microorganisms, resulting in up to twofold larger aggregates. This increase in aggregate size was strain-dependent. However, the aggregates that developed during the first 48 h broke into smaller structures later on. A microscopic analysis of the microaggregates revealed that notably the larger microaggregates harbored bacteria and that microaggregates had a sheltering effect on living cells, especially when exposed to desiccation stress. Additionally, aggregate formation was analyzed in the presence of a Pseudomonas protegens mutant strain (CHA211) with increased production capability of extracellular polymeric substances (EPS). About fivefold higher survival rates of culturable cells were observed after desiccation for this EPS overproducing mutant strain in comparison to the wild-type. Our results hint at an aggregate formation process characterized by a rapid occlusion of mineral compounds, and, after the addition of microorganisms, the bacterial colonization of small microaggregates, leading to an increase in aggregate size. The further development of the aggregate size distribution varied depending on the presence of microbial taxa and was modulated by environmental conditions like desiccation events.

13277. 题目: Multifunctional Pd/Fe-biochar composites for the complete removal of trichlorobenzene and its degradation products
文章编号: N19060102
期刊: Journal of Environmental Management
作者: Lu Han, Jingchun Yan, Linbo Qian, Wenying Zhang, Mengfang Chen
更新时间: 2019-06-01
摘要: To elucidate the effect of structure and property of biochar on the structure-activity relationship among the composites of biochar supported Pd/Fe and 1,2,4-trichlorobenzene (1,2,4-TCB) and its dechlorination products, biochar supported Pd/Fe nanoparticles with different mass ratios were investigated for the enhanced removal of 1,2,4-TCB (52 μmol/L) and its dechlorination products. 1,2,4-TCB was removed through the electrochemical dechlorination by Pd/Fe and adsorption by biochar simultaneously. As the mass ratio of CS700 to Pd/Fe was 0.1:1, biochar within the Pd/Fe-CS7000.1 system played a significant role in the adsorption of 1,2,4-TCB. However, there is little adsorption to biochar for dechlorination products due to strong competition by 1,2,4-TCB. As the mass ratio of CS700 to Pd/Fe was increased to 5:1, 1,2,4-TCB was completely removed from the solution by the composites within 0.5 h. The dechlorination products (1,2-DCB, MCB, benzene and trace 1,3-DCB) were completely sequestered on solid phase but absent in aqueous solution. However, the excessive biochar increased the inaccessibility of 1,2,4-TCB or decreased the reactive sites of Pd/Fe leading to the less dechlorination of 1,2,4-TCB. The alkaline biochar did not influence the chemical reactivity of Pd/Fe in the composites and buffered the acid and alkaline solutions with pH being maintained at neutral conditions under initial pH ranging from 3.07 to 10.03. The highly hydrophobicity of biochar could maintain the affinity of the composite for the chlorinated compounds even if the concentration of 1,2,4-TCB was up to 80.9% of its aqueous solubility. This study provides efficient synergistic removal support for the treatment of TCB affected groundwater.
图文摘要:

13278. 题目: Insight into the interaction mechanism of iron ions with soil humic acids. The effect of the pH and chemical properties of humic acids
文章编号: N19060101
期刊: Journal of Environmental Management
作者: Patrycja Boguta, Valeria D'Orazio, Nicola Senesi, Zofia Sokołowska, Katarzyna Szewczuk-Karpisz
更新时间: 2019-06-01
摘要: The main aim of this work was to study the mechanisms of interaction between iron(II) ions and humic acids as a function of pH, iron concentration and various humic acids chemical properties, including the degree of humification, elemental composition, aromaticity and content of acidic functional groups. The results indicated that iron was bound by humic acids at pH 7 in amounts ∼2 times higher than at pH 5 (averaged capacities: 117 and 57 cmol/kg, respectively). Iron binding at pH 7 increased with increasing the total carboxylic and phenolic groups content and the degree of humification of humic acids (R-coefficients: 0.99 and 0.95, respectively). The stability of humic acid-iron complexes at pH 7 were only slightly lower than at pH 5 due to iron hydroxides formed at pH > 5 (averaged stability constants: 5.18 and 5.26, respectively). Iron coordination mode varied depending on pH: at pH 5, the bidentate (chelate) mode dominated, whereas at pH 7 the bridging mode appeared prevalent. The total amount of bound iron was much smaller than the content of the carboxylic and phenolic groups in humic acids, on average by ∼80 (pH 7) and ∼90.1% (pH 5) indicating the occurrence of steric effects in humic acid structure i.e. the reduction of the complexation capacity of free functional groups by adjacent groups occupied by iron and/or the formation of intramolecular aggregates with iron hindering the access of further metal ions. At pH 5 the complexes were soluble in the iron concentration range positively correlated to carboxylic and phenolic groups content, showing the protective nature of negatively charged functional groups on the stability of the solution. At this pH, the destabilization of the system was governed by the neutralization of humic acid charged structures by metal cations and the compression of the double electric layer. At pH 7 the stability of the humic acid-iron solution was largely determined by the form of iron, mainly by the precipitation of metal hydroxides acting as a flocculant destabilizing the solution by co-precipitation of humic acid-iron complexes.
图文摘要:

13279. 题目: Biochar-Mediated Anaerobic Oxidation of Methane
文章编号: N19053106
期刊: Environmental Science & Technology
作者: Xueqin Zhang, Jun Xia, Jiaoyang Pu, Chen Cai, Gene W. Tyson, Zhiguo Yuan, Shihu Hu
更新时间: 2019-05-31
摘要: Biochar was recently identified as an effective soil amendment for CH4 capture. Corresponding mechanisms are currently recognized to be from physical properties of biochar, providing a favorable growth environment for aerobic methanotrophs which perform aerobic methane (CH4) oxidation. However, our study shows that the chemical reactivity of biochar can also stimulate anaerobic oxidation of CH4 (AOM) by anaerobic methanotrophic archaea (ANME) of ANME-2d, which proposes another plausible mechanism for CH4 mitigation by biochar amendment in anaerobic environments. It was found that, by adding biochar as the sole electron acceptor in an anaerobic environment, CH4 was biologically oxidized, with CO2 production of 106.3 ± 5.1 μmol g–1 biochar. In contrast, limited CO2 production was observed with chemically reduced biochar amendment. This biological nature of the process was confirmed by mcr gene transcript abundance as well as sustained dominance of ANME-2d in the microbial community during microbial incubations with active biochar amendment. Combined FTIR and XPS analyses demonstrated that the redox activity of biochar is related to its oxygen-based functional groups. On the basis of microbial community evolution as well as intermediate production during incubation, different pathways in terms of direct or indirect interactions between ANME-2d and biochar were proposed for biochar-mediated AOM.

13280. 题目: Does the element composition of soils of restored wetlands resemble natural wetlands?
文章编号: N19053105
期刊: Geoderma
作者: Guodong Wang, Marinus L. Otte, Ming Jiang, Ming Wang, Yuxiang Yuan, Zhenshan Xue
更新时间: 2019-05-31
摘要: The main goal of this study was to assess if wetland restoration changes soil biogeochemistry, here measured as organic matter content (OM) and element concentrations of the soils, back to its original state. We selected nine sampling sites in the Sanjiang Plain, China, that had two or three of the wetland types ‘undisturbed/natural’, ‘restored’, and ‘paddy field’ close to each other. The paddy fields were originally established on natural wetlands, and the original wetland soils would therefore have been similar. We analyzed the soils for element composition, OM, as well as electrical conductivity (EC) and pH. Distinct differences between undisturbed wetlands, restored wetlands and paddy fields existed in terms of element composition, OM, and EC, with most values for restored wetlands in-between those of undisturbed wetlands and paddy fields. Ordination analysis of the element concentrations by RDA identified that OM explained most variance (23.9% of 34.4% of total). OM correlated positively with N and S, negatively with most metals. Disturbance of wetland soils by agricultural activities most likely depleted OM of the soils, which in turn altered the concentrations of most elements. Restoration, even if only a few years ago, recovered the OM and changed the element contents in the direction of a natural condition to some extent. This information is important for restoration of wetlands, because to be successful, not only hydrology and biodiversity need to be restored but also the soil composition and biogeochemistry. It further can be used for assessment of success of wetland restoration.

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