20年3月22日文獻情報
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本次文獻簡報涉及海洋沉積物有機物記錄的氣候變化與生物事件[1]，保護耕地對土壤有機質累積作用[2]，水稻土有機質對甲烷釋放和水稻產量影響[3]，土壤有機質穩定性與酶活性關係[4]，有機質促進膜曝氣細菌-藻類共生系統藻類的增殖[5]，生物脫氮工藝中溶解性有機氮的特徵[6]，叢枝菌根真菌與土壤有機質關係[7]，人為影響海灣氣溶膠有機物的螢光光譜特性與同位素證據[8]，有機肥有機質促進水稻土壤中砷耗損[9]，生物炭降低溼地N2O增加甲烷產量[10]，胞外聚合物蛋白質對Cd毒性影響[11]，基質改善劑對鋁土聚集伴生有機質改善和穩定[12]，腐殖酸與汞結合[13]，垃圾滲濾液有機物去除[14]，非飽芳香烴消毒副產物前驅體的去除[15]，缺氧-富氧界面Cr-NOM-Fe膠體形成和遷移[16]。
1. 題目: Million-year secular variations in the elemental geochemistry of Devonian marine records and a link to global climate and bioevents: Prague Basin, Czechia文章編號: N20032216
期刊: Sedimentary Geology
作者: Daniel Šimíček, Ondřej Bábek, Martin Faměra, Jiří Kalvoda
更新時間: 2020-03-22
摘要: The sedimentary record is affected by periodic and/or random variations in Earth's near-surface conditions, such as the Milankovitch band variations, which are responsible for small-scale cyclicity in distal marine settings. However, the controlling factors of normal field-scale sedimentary cycles operating on Myr-scale that dominate the stratigraphic record remain largely enigmatic. The Lower to Middle Devonian succession (Lochkovian to Givetian) of the Prague Basin, Czechia, is represented by an alternation of largely deep-marine carbonates and shales with typical duration of ~5–7 Myr. We studied the elemental geochemistry of bulk rock samples supported by XRD mineralogy and TOC concentrations. Stratigraphic distribution of the organic-productivity proxies, redox proxies, Ce/Ce* and Pr/Pr* anomalies, and TOC, supported by lithology, allochem composition and field gamma-ray spectrometry, indicates that the Prague Basin was governed by two alternating depositional modes. The oligotrophic mode is characterised by low values of productivity proxies and U/Th ratios, good bottom water oxygenation, heterotrophic skeletal producers, and facies typical of homoclinal ramp settings. The mesotrophic mode is characterised by high U/Th, elevated organic productivity, less oxic bottom conditions, relatively abundant autotrophic skeletal producers and deposition on a distally steepened ramp. The modes were in phase with the Devonian climatically driven environmental changes. We assume that the elevated silicate weathering rates during warmer periods, as previously reported, resulted in higher nutrient input to the seas setting the marine system into the mesotrophic mode. Cooler periods led to oligotrophic water conditions. The global Devonian bioevents show recurrence intervals of the same order as the trophic modes but they typically coincided with the transition between the modes. It is suggested that marine biotic assemblages and the associated carbonate production became unstable during perturbations of the carbon cycle.
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2. 題目: May conservation tillage enhance soil C and N accumulation without decreasing yield in intensive irrigated croplands? Results from an eight-year maize monoculture文章編號: N20032215
期刊: Agriculture, Ecosystems & Environment
作者: Andrea Fiorini, Roberta Boselli, Stefania Codruta Maris, Stefano Santelli, Federico Ardenti, Federico Capra, Vincenzo Tabaglio
更新時間: 2020-03-22
摘要: Intensive management of agroecosystems has been widely indicated as major responsible for soil degradation, thus negatively impacting on relationships between agriculture and climate change. Conservation tillage (i.e. no-till and minimum tillage) has been recommended for enhancing soil organic carbon (SOC) and total nitrogen (STN) stocks while having a positive impact on food security, biodiversity, water quality and the environment. Nevertheless, positive responses were mainly reported in hot and semiarid climates, with rainfed crops and low N fertilization rates. Therefore, the main objective of this study was to test the adoption of conservation tillage in intensive maize cropping systems under temperate soil, with high N fertilization rate (> 200 kg N ha−1 yr−1) and organic matter input (i.e. manure distribution and high biomass return), and with permanent optimum water moisture due to irrigation. We conducted an 8-year field experiment on a maize (Zea mays L.) monoculture to assess: (i) the effect of no-till (NT) and minimum tillage (MT), on grain yield and biomass return as compared with conventional tillage (CT); (ii) how tillage systems affect the evolution of SOC and STN levels over time under these conditions; (iii) soil aggregation processes and mechanisms leading to SOC and STN changes in the long-term. Results showed that MT increased maize grain yield (+7 %) and total biomass (+10 %) compared with CT. Conversely, NT reduced maize grain and biomass production during the initial 5-year transition, but afterwards increased maize yield up to that of CT. At the end of the experiment, SOC sequestration was increased under NT and MT by 1.45 and 1.52 Mg C ha−1 yr−1 compared with CT, respectively. Also, STN accumulation was higher under NT and MT than under CT (+0.15 and +0.17 Mg N ha−1 yr−1, respectively). Most of such a SOC and STN increase was located into C- and N-rich macroaggregates. Within those macroaggregates (large macroaggregates, LM; small macroaggregates, sM), we found that C and N pools associated to mM accounted for between 41 and 65 % of total C and N content in NT and MT systems across the different soil layers, which is beneficial for long-term C and N stabilization in soils. Thus, introducing conservation tillage within intensive agricultural context devoted to maize monoculture as that of the Po Valley should be recommended to: (i) maintain (or even increase) maize yield, and (ii) enhance SOC and STN accumulation and stabilization.
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3. 題目: Reducing greenhouse gas emissions and grain arsenic and lead levels without compromising yield in organically produced rice文章編號: N20032214
期刊: Agriculture, Ecosystems & Environment
作者: Syed Faiz-ul Islam, Andreas de Neergaard, Bjoern Ole Sander, Lars Stoumann Jensen, Reiner Wassmann, Jan Willem van Groenigen
更新時間: 2020-03-22
摘要: Flooded rice production is crucial to global food security, but there are associated environmental concerns. In particular, it is a significant source of methane (CH4) and nitrous oxide (N2O) emissions and a large consumer of water resources, while arsenic levels in the grain are a serious health concern. There is also a tendency to use more organic fertilisers to close nutrient cycles, posing a threat of even higher GHG emissions and grain arsenic levels. It has been shown that alternate wetting and drying (AWD) water management reduces both water use and GHG emissions, but success at maintaining yields varies. This study tested the effect of early AWD (e-AWD) versus continuous flooding (CF) water management practices on grain yields, GHG emissions and grain arsenic levels in a split-plot field experiment with organic fertilisers under organic management. The treatments included: i) farmyard manure, ii) compost, and iii) biogas digestate, alone or in combination with mineral fertiliser. The e-AWD water regime showed no difference in yield for the organic treatments. Yields significantly increased by 5–16 % in the combination treatments. Root biomass and length increased in the e-AWD treatments up to 72 and 41 %, respectively. The e-AWD water regime reduced seasonal CH4 emissions by 71–85 % for organic treatments and by 51–76 % for combination treatments; this was linked to a 15–47 % reduction in dissolved organic carbon (DOC), thereby reducing methanogenesis. N2O emissions increased by 23–305 % but accounted for <20 % of global warming potential (GWP). Area and yield-scaled GWPs were reduced by 67–83 %. The e–AWD regime altered soil redox potentials, resulting in a reduction in grain arsenic and lead concentrations of up to 66 % and 73 % respectively. Grain cadmium levels were also reduced up to 33 % in organic treatments. Structural equation modelling showed that DOC, redox, ammonium and root biomass were the key traits that regulated emissions and maintained yield. Despite the fact that the experiment was conducted in the dry-season when soil moisture conditions can be relatively well-controlled, our findings should be confirmed in multi-year studies in farmers' fields. These results suggest that in flooded rice systems receiving organic amendments or organic management, the e-AWD water regime can achieve multiple environmental and food safety objectives without compromising yield.
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4. 題目: Response of soil specific enzyme activity to vegetation restoration in the Loess hilly region of China文章編號: N20032213
期刊: CATENA
作者: Hongwei Xu, Qing Qu, Bingbing Lu, Peng Li, Sha Xue, Guobin Liu
更新時間: 2020-03-22
摘要: It is well-established that changes to land use changes affect soil enzyme activity; however, little is known about the changes in soil specific enzyme activity per unit soil organic carbon (SOCE) and soil microbial biomass carbon (MBCE) after vegetation restoration in the arid and semi-arid regions of China. The objectives of this study were to investigate the effects of long-term vegetation restoration on soil specific enzyme activity and to elucidate the relationship between specific enzyme activity and soil organic carbon (SOC) stability in the Loess hilly region of China. We determined three enzymes (saccharase, urease, and phosphatase) activity at 0–50 cm soil depths in plots under vegetation restoration for different lengths of time and supporting different vegetation types (grassland, 2–30 recovery years; shrubland, 5–47 recovery years; and forestland, 5–56 recovery years). SOCE and the geometric mean of enzyme activity (GMEA) at 0–20 cm depth initially increased and then decreased, whereas overall MBCE at 0–10 cm depth decreased with time. Overall, SOCE and GMEA decreased with soil depth, and were significantly and negatively correlated with SOC stability index (SI). In comparison, the relationship between MBCE and SI was non-significant. Overall, our data showed that specific enzyme activity and GMEA responded to vegetation restoration, with SOCE and GMEA negatively impacting SOC stability.
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5. 題目: Organic carbon promotes algae proliferation in membrane-aeration based bacteria-algae symbiosis system (MA-BA)文章編號: N20032212
期刊: Water Research
作者: Han Zhang, Weijia Gong, Weichen Zeng, Zhongsen Yan, Baohui Jia, Guibai Li, Heng Liang
更新時間: 2020-03-22
摘要: In the bacteria-algae (BA) system, the amount of oxygen produced by the algae is always insufficient for the organic carbon degradation, resulting in less inorganic carbon (IC) production. Meanwhile, the conventional extra aeration method always causes CO2 stripping and IC loss. Both two reasons limited the algae boosting. Membrane aeration (MA) has the excellent capability of organic carbon thorough degradation and gas blown-off control. In this study, MA-BA was employed to investigate the effect of organic carbon on the algae growth. Results showed that COD had a positive correlation with Chlorophyll-a (Chl-a) and algae proliferation in MA-BA system according to the redundancy analysis (RDA). The biggest Chl-a concentration (20.95 mg/cm2) occurred in R4 (COD = 400 mg/L). Stimulated algal population changed nutrient removal pathway changing from bacterial action to algae action. Meantime, Soared algae accumulation would selectively excite the abundance of bacteria that supported the algae growth, such as Acinetobacter exhibited a growing trend as the increase of influent COD, especially in the inner biofilm. This paper provided new insight into the effect of organic carbon on the algae in a novel MA-BA system, which will be helpful for future research.
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6. 題目: Characteristics of dissolved organic nitrogen in effluent from a biological nitrogen removal process using sludge alkaline fermentation liquid as an external carbon source文章編號: N20032211
期刊: Water Research
作者: Haidong Hu, Sijia Ma, Xuxiang Zhang, Hongqiang Ren
更新時間: 2020-03-22
摘要: The addition of sludge alkaline fermentation liquid (SAFL) to biological nutrient removal (BNR) processes has been widely shown to reduce the dissolved inorganic nitrogen (DIN) in the effluent. However, knowledge regarding the effect of using SAFL in a BNR as an additional carbon source on the characteristics of dissolved organic nitrogen (DON) in the effluent is limited. This study investigated the effect of SAFL addition on effluent DON features and microbial community dynamics in a BNR process treating municipal wastewater. The performance of SAFL was compared with other two reactors (i.e., without an external carbon source and with the addition of sodium acetate). The results showed that the addition of SAFL can significantly reduce effluent DON (p < 0.05). The effluent DON was slightly higher with SAFL than with sodium acetate, but the bioavailable DON of the two reactors was similar (1.06 ± 0.11 vs 1.04 ± 0.12 mg/L, respectively, p > 0.05). The SAFL addition led to a decreased percentage of low molecular weight DON (p < 0.05) as well as an increased ratio of fulvic-like and humic-like substances to proteins-like substances. Moreover, the SAFL addition resulted in a lower percentage of substances resembling proteins/amino sugars and a higher percentage of lignin-like molecules than sodium acetate. These features accounted for the low DON bioavailability. The SAFL promoted the increased abundance of Bacteroidetes, Chloroflexi, Comamonadaceae and Rhodocyclaceae, which could be associated with the decreased effluent DON and its bioavailability. This study indicates that using SAFL as a BNR carbon source not only improves the removal of DIN but also reduces effluent DON and specifically DON bioavailability. These results facilitate the acquisition of comprehensive knowledge regarding the use of SAFL as an alternative external carbon source in the BNR process.
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7. 題目: Arbuscular mycorrhizal fungal communities in the rhizospheric soil of litchi and mango orchards as affected by geographic distance, soil properties and manure input文章編號: N20032210
期刊: Applied Soil Ecology
作者: Shangtao Jiang, Xiaoxuan Hu, Yalong Kang, Changyan Xie, Xiangrui An, Caixia Dong, Yangchun Xu, Qirong Shen
更新時間: 2020-03-22
摘要: Utilization of arbuscular mycorrhizal (AM) resources to improve, or even maintain agroecosystem sustainability requires a thorough understanding of the biotic and abiotic factors that impact AM fungal communities. AM symbiosis is important in mango and litchi trees, two economically important fruit crops in China, but there is little information on the AM fungi associated with these trees or their responses to organic fertilizer. Using Illumina high-throughput sequencing we analyzed AM colonization, spore density, and community composition and diversity in the rhizospheric soil from 16 mango orchards and 16 litchi orchards located in southern China. Ours was a regional scale study and in general, we found that the majority of AM fungi OTUs belonged to the families Glomeraceae, followed by Gigasporaceae, Paraglomeraceae, Acaulosporaceae and Diversisporaceae. Glomus and Paraglomus were the genera that differed most in abundance between the rhizospheric soil of mango and litchi. AMF community composition was impacted by latitude and longitude and soil characteristics such as, NO3−-N, NH4+-N, available-P, and soil organic carbon (SOC). The sampling sites were in areas of medium to low altitude, and there was no significant correlation between altitude and AM fungal richness. We found that higher soil nutrient content, particularly available-P, was negatively correlated with AM colonization. Our results also showed that some of the AM genera responded differently to environmental variables. Structural equation modeling (SEM) demonstrated that SOC not only had a direct positive effect on AMF richness, but also an indirect negative effect, due to increased soil fertility. Our findings have enabled a deeper insight into the impacts of organic fertilizer on AM fungal communities, which will be valuable when considering AM symbiosis in orchard management.
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8. 題目: Composition and sources of aerosol organic matter in a highly anthropogenic influenced semi-enclosed bay: Insights from excitation-emission matrix spectroscopy and isotopic evidence文章編號: N20032209
期刊: Atmospheric Research
作者: Yunchao Wu, Xiaoping Huang, Zhijian Jiang, Songlin Liu, Lijun Cui
更新時間: 2020-03-22
摘要: Organic matter in aerosols is an important allochthonous source of organic carbon and nitrogen in coastal waters. In this study, we investigated the constituents, sources, and formation process of organic matter in aerosols using excitation−emission matrix (EEM) spectroscopy and stable isotopes. The concentration of aerosol organic matter (AOM), including particle organic matter (POM) and water-soluble organic matter (WSOM), were higher in the northeast monsoon (NEM) season than in the southwest monsoon and typhoon (SWM) season due to the considerable contribution of organic aerosols from the Pearl River Delta (PRD), eastern mainland China and local emissions. The results of stable isotope (δ13C and δ15N) combined with a MixSIAR model showed that fossil fuel combustion (vehicle exhausts and coal combustion) was the most important source of aerosol organic matter, which contributed more than 60% of the total AOM input, throughout the year. The EEM spectroscopy results indicated that protein-like and non-N-containing species were the primary components of aerosol organic matter, while highly-oxygenated species, mostly humic-like substances (HULIS), were identified only in the NEM season. The highly-oxygenated species in the NEM season may be attributed to the formation of secondary organic aerosols induced by higher ozone levels and increased organic radical through the severe pollution in this season.
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9. 題目: Enhanced arsenic depletion by rice plant from flooded paddy soil with soluble organic fertilizer application文章編號: N20032208
期刊: Chemosphere
作者: Sixue He, Xin Wang, Chujing Zheng, Lu Yan, Liang Li, Rui Huang, Hao Wang
更新時間: 2020-03-22
摘要: In this study, the promoting effect of soluble organic fertilizer (SOF) on arsenic (As) release and depletion by rice plant in flooded paddy soil was investigated. The increased soil DOC with SOF incorporation displayed a significantly positive correlation with As in soil solution (r = 0.415, p < 0.01). Porewater As with SOF addition was higher than control from 77 days. Soil As depletion by rice plant was enhanced by SOF application, with porewater As in SM + Rice + SOF being 49% lower than that in SM + Rice at harvest. Compared to SM + Rice, the averaged soil profile of As measured by diffusive gradients in thin films (DGT) declined by 4% in tillering stage and by 16% in grain-filling stage in SM + Rice + SOF. As a result, As accumulation in each rice plant was increased by 35% at the presence of SOF, with 92% of total As retained in roots. With SOF amendment, 8% of total As in the tested soil was removed by harvesting rice biomass including root. In this way, an estimated 184 mg As m−2 can be depleted from paddy soil at the end of one rice-growing season. These results revealed the potential of SOF in enhancing soil As depletion by rice plant under flooded condition, providing a cost-effective pathway for efficient cleanup of bioavailable As from rice paddies.
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10. 題目: Biochar Reduces Nitrous Oxide but Increases Methane Emissions in Batch Wetland Mesocosms文章編號: N20032207
期刊: Chemical Engineering Journal
作者: Xin Chen, Hui Zhu, Gary Bañuelos, Brian Shutes, Baixing Yan, Rui Cheng
更新時間: 2020-03-22
摘要: Biochar was added into constructed wetlands (CWs) as an amendment to the main substrate (i.e., coarse gravel) for improving the removal efficiency of pollutants and mitigating greenhouse gas (GHG) emissions. Four types of mesocosm-scale CWs, i.e., unamended subsurface batch constructed wetland (SSBCWs) and surface batch CWs (SBCWs), and biochar-amended SSBCWs and SBCWs, were established in this study. The SSBCWs outperformed SBCWs in both removing pollutants (particularly COD, NO3--N and TN) and reducing the global warming potential (GWP), irrespective of adding biochar or not. The amendment of biochar improved the efficacy of CWs for removing pollutants and mitigating GHG emissions in both configurations of CWs. The highest removal percentages of COD (89.6%), NO3--N (89.2%) and TN (92.5%) were obtained in biochar-amended SSBCWs, followed by unamended SSBCWs, biochar-amended SBCWs, and unamended SBCWs. The lowest GWP (5.252 mg/m2/h) was simultaneously obtained in biochar-amended SSBCWs, and the addition of biochar reduced GWP by 57.3% and 3.0% for SSBCWs and SBCWs, respectively. The abatement of GHG by biochar addition was mainly reflected in reduction of N2O fluxes, while the CH4 fluxes were promoted and the CO2 fluxes were not affected. The quantitative PCR results indicate that the reduced N2O fluxes in biochar-amended CWs were driven by the enhanced transcription of the nosZ gene and the ratio of nosZ / (nirS + nirK). This study demonstrates that biochar-amended SSBCWs can be an ideal alternative for design and application of CWs for removing pollutants and abating GHG emissions in the future.
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11. 題目: The complexation with proteins in extracellular polymeric substances alleviates the toxicity of Cd (II) to Chlorella vulgaris文章編號: N20032206
期刊: Environmental Pollution
作者: Qiting Xie, Na Liu, Daohui Lin, Ruohua Qu, Qiongzhi Zhou, Fei Ge
更新時間: 2020-03-22
摘要: The complexation with extracellular polymeric substances (EPS) greatly reduces the toxicity of heavy metals towards organisms in the environment. However, the molecular mechanism of EPS−metal complexation remains unclear owing to the limitation of precise analysis for key fractions and functionalities in EPS that associate with metals. Herein, we explored the EPS−Cd (II) complexation by fluorescence excitation emission matrix coupled with parallel factor (EEM−PARAFAC), two-dimensional Fourier transform infrared correlation spectroscopy (2D-FTIR−COS) and X-ray photoelectron spectroscopy (XPS), attempting to explain the mechanisms of EPS in alleviating Cd (II) toxicity toward a green alga Chlorella vulgaris (C. vulgaris). When the algal EPS were removed, the cell internalizations of Cd (II), growth inhibition rate and chlorophyll autofluorescence increased, but the surface adsorption and esterase activities decreased, indicating that the sorption of Cd (II) by EPS was crucial in alleviating the algal toxicity. Moreover, the complexation with proteins in EPS controlled the sorption of Cd (II) to algal EPS, resulting in the chemical static quenching of the proteins fluorescence by 47.69 ± 2.37%. Additionally, the complexing capability of the main functionalities, COO− and C–OH in proteins with Cd (II) was stronger than that of C–O(H) and C–O–C in polysaccharides or C–OH in the humus-related substances. Oxygen atom in protein carboxyl C–O might be the key site of EPS−Cd (II) complexation, supported by the modified Ryan−Weber complexation model and the obvious shift of oxygen valence-electron signal. These findings provide deep insights into understanding the interaction of EPS with heavy metals in aquatic environment.
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12. 題目: Improvement of aggregate-associated organic carbon and its stability in bauxite residue by substrate amendment addition文章編號: N20032205
期刊: Land Degradation & Development
作者: Tao Tian, Zheng Liu, Feng Zhu, William Hartley, Yuzhen Ye, Shengguo Xue
更新時間: 2020-03-22
摘要: Bauxite residue has extreme alkalinity, poor aggregate stability, and low organic carbon content, which limits plants growth at large‐areas bauxite residue disposal areas. Soil formation of bauxite residue is one of the effective approaches to transform bauxite residue into a soil‐like medium for revegetation. In order to improve aggregate stability and organic carbon content in the short term, addition of substrate amendments is crucial to accelerate soil formation of bauxite residue. Nevertheless, the effect of different amendments on the stability, organic and humic substances distribution of bauxite residue aggregate is unclear. Therefore, a column experiment was used to investigate the distribution and stability of aggregate, and aggregate‐associated carbon by adding phosphogypsum and vermicompost (PVC), and biosolids and microorganism (BSM). The average particle sizes of CK (control check), PVC, and BSM treatments were observed to be ~114, ~157, and ~188 nm, respectively. Compared with CK treatment, the contents of organic carbon, humic acid, and fulvic acid following PVC treatment increased by 1.65, 1.59, and 1.57 times, respectively, and the increased contents of organic carbon, humic acid, and fulvic acid following BSM treatment reached 2.90, 2.69, and 2.60 times, respectively. Results demonstrated that amendment additions enhanced aggregate stability and carbon sequestration, but the effects of BSM treatment were better than those of PVC treatment. The findings offer an evidence that BSM treatment is a feasible approach to accelerate soil formation of bauxite residue, which shows promising applications to reclaim bauxite residue disposal areas. This article is protected by copyright. All rights reserved.
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13. 題目: Effects of mercury binding by humic acid and humic acid resistance on mercury stress in rice plants under high Hg/humic acid concentration ratios文章編號: N20032204
期刊: Environmental Science and Pollution Research
作者: Yue Liu, Liangliang Zhi, Shaoqi Zhou, Feng Xie
更新時間: 2020-03-22
摘要: Due to the nonsystematic nature of previous studies on mercury (Hg) mobility with humic substances (HS) in terrestrial ecosystems and the uncertainty of Hg accumulation in plants, oxygen-rich humic acid (HA), which is the main component of HS, was used as the target in this study. Batch sorption tests and a series of pot experiments were designed to investigate the effect of HS on Hg binding and therefore Hg uptake in rice plants under extreme conditions, i.e., a high Hg/HS concentration ratio. The results showed that HA was eligible for Hg binding, though it has a tiny proportion of sulfur according to its characteristics analysis. The binding of HA and Hg was a chemisorption process in a single layer that followed the pseudo-second order and Langmuir models, and it was also verified that the pH was dependent on the ion strength associated with high Hg/HA concentration ratios. Based on the pot experiments, the performance of HA with Hg was investigated. The Hg in the toxicity characteristic leaching procedure (TCLP) leachate under high Hg/HA concentration ratios declined significantly, and accordingly, all treatments met the concentration criteria of 0.1 mg/l (GB 5085.3–2007) for wastes after 30 days of exposure. At concentration ratios of 50, 25, and 10 μg Hg/mg HA, we observed that HA application promoted rice plant growth, as reflected in the increase of fresh weight of different organs. Regarding accumulation in the soil-plant system, the degradation of HA to smaller molecules by rhizosphere microorganisms and organic acids in roots made HA available for plant uptake through the vascular bundle in roots, thus promoting Hg transformation in plants to a certain extent. However, considering the decline in available Hg in the soil, the Hg concentrations of roots, straw, and grains in the ripening stage were found to be lower than those in the standalone Hg treatments. HA clearly has a direct effect on Hg and an indirect influence on plants exposed to Hg under extreme conditions (very high Hg/HA concentration ratios); thus, the biogeochemical behavior of Hg at high Hg/HA concentration ratios should be considered and further investigated.
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14. 題目: Efficient treatment for landfill leachate through sequential electrocoagulation, electrooxidation and PMS/UV/CuFe2O4 process文章編號: N20032203
期刊: Separation and Purification Technology
作者: Farshid Ghanbari, Junxue Wu, Masoumeh Khatebasreh, Dahu Ding, Kun-Yi Andrew Lin
更新時間: 2020-03-22
摘要: Landfill leachate is well known as one of the most serious environmental problems due to the high concentrations of organic and inorganic compounds. Several methods have been reported for the treatment and detoxification of landfill leachate. However, high organic load and the presence of refractory organic pollutants resulted in inefficiency of those methods when at least applied alone. The present work recommended a sequence of processes: electrocoagulation (EC), electrooxidation (EO) and peroxymonosulfate (PMS)/UV/CuFe2O4 (sulfate radical-based advanced oxidation process, SR-AOP) for treatment of landfill leachate. A parametric evaluation was conducted for each process including pH, current densities, electrode type, catalyst loading, PMS dosage and reaction time. Al and Fe electrodes for the EC process and Pt, PbO2 and graphite for the EO process were investigated. The results showed that Fe and PbO2 were more efficient than other electrodes for EC and EO respectively. COD removal efficiencies were up to 60.0, 50.0 and 77.9% for EC, EO and SR-AOP, respectively. Removal efficiencies for the sequential process were 95.6, 90.5, 91.6 and 99.8% for COD, TOC, BOD and ammonia (NH4-N) respectively. Biodegradability was significantly enhanced according to the BOD/COD ratio and the average oxidation state of carbon (AOSC). Biodegradation test indicated that the organic matter was completely degraded by activated sludge in seven days. Phytotoxicity experiments also demonstrated a considerable reduction in phytotoxicity after each process. The results confirmed that the proposed sequence is efficient for COD removal, phytotoxicity reduction and biodegradability improvement being an acceptable treatment for landfill leachates.
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15. 題目: Ferrate(VI) pretreatment before disinfection: An effective approach to controlling unsaturated and aromatic halo-disinfection byproducts in chlorinated and chloraminated drinking waters文章編號: N20032202
期刊: Environment International
作者: Jiaqi Liu, Henry Lujan, Birendra Dhungana, William C. Hockaday, Christie M. Sayes, George P. Cobb, Virender K. Sharma
更新時間: 2020-03-22
摘要: Disinfection is an essential process of drinking water treatment to eliminate harmful pathogens, but it generates potentially toxic disinfection byproducts (DBPs). Ferrate (FeO42-, Fe(VI)) was used to pre-oxidize natural organic matter (NOM, the precursor of DBPs) in source water to control DBP formation in subsequent chlorine or chloramine disinfection. Currently, it is unclear how Fe(VI) changes the structure of NOM, and no information details the effect of Fe(VI) pretreatment on the aromatic DBPs or the speciation of overall DBPs generated in subsequent disinfection of drinking water. In the present paper, Fe(VI) was applied to pretreat simulated source water samples at a Fe(VI) to dissolved organic carbon mole ratio of 1:1 at pH 8.0. 13C nuclear magnetic resonance spectroscopy was newly employed to characterize NOM in simulated source waters with and without Fe(VI) treatment, and it was demonstrated that Fe(VI) converted unsaturated aromatic C functional groups in NOM to saturated aliphatic ones. High-resolution mass spectrometry (HRMS) and high performance liquid chromatography/triple quadrupole MS were applied to analyze the DBPs generated in chlorination and chloramination of the source waters with and without Fe(VI) pretreatment. It was confirmed that Fe(VI) pretreatment followed by chlorination (or chloramination), generated DBPs containing less unsaturated, halogenated, and aromatic moieties than chlorination (or chloramination) without pretreatment by Fe(VI). Finally, the cytotoxicity of disinfected drinking water samples were assessed with the human epithelial colorectal adenocarcinoma Caco-2 cell line (a model of the intestinal barrier for ingested toxicants), and the results show that Fe(VI) pretreatment detoxified the chlorinated and chloraminated drinking waters.
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16. 題目: Formation and Transport of Cr(III)-NOM-Fe Colloids upon Reaction of Cr(VI) with NOM-Fe(II) Colloids at Anoxic–Oxic Interfaces文章編號: N20032201
期刊: Environmental Science & Technology
作者: Peng Liao, Chao Pan, Wenyu Ding, Wenlu Li, Songhu Yuan, John D. Fortner, Daniel E. Giammar
更新時間: 2020-03-22
摘要: Natural organic matter-iron (NOM-Fe) colloids are ubiquitous at anoxic–oxic interfaces of subsurface environments. Fe(II) or NOM can chemically reduce Cr(VI) to Cr(III), and the formation of Cr(III)-NOM-Fe colloids can control the fate and transport of Cr. We explored the formation and transport of Cr(III)-humic acid (HA)-Fe colloids upon reaction of Cr(VI) with HA-Fe(II) colloids over a range of environmentally relevant conditions. Cr(VI) was completely reduced by HA-Fe(II) complexes under anoxic conditions, and the formation of Cr(III)-HA-Fe colloids depended on HA concentration (or molar C/Fe ratio) and redox conditions. No colloids formed at HA concentrations below 3.5 mg C/L (C/Fe ratio below 1.6), but Cr(III)-HA-Fe colloids formed at higher HA concentrations. In column experiments, Cr(III)-HA-Fe(III) colloids formed under oxic conditions were readily transported through sand-packed porous media. Colloidal stability measurements further suggest that Cr(III)-HA-Fe colloids are highly stable and persist for at least 20 days without substantial change in particle size. This stability is attributed to the enrichment of free HA adsorbed on the Cr(III)-HA-Fe colloid surfaces, intensifying the electrostatic and/or steric repulsion interactions between particles. The new insights provided here are important for evaluating the long-term fate and transport of Cr in organic-rich redox transition zones.
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