101. 题目: Batch and Continuous Design of a Full‐Scale Treatment Facility for Removing Dissolved Natural Organic Matter
期刊: Clean - Soil, Air, Water
作者: Bulent Sari, Ali Erdem Oztas, Olcayto Keskinkan, Cagatayhan Bekir Ersu
摘要: In this study, batch and continuous flow adsorption experiments were carried out and the design of a full‐scale facility (with an operating capacity of 2.5 × 105 m3/day) for removing dissolved natural organic matter (DNOM) from lake (Catalan Dam Lake) water was demonstrated. The adsorption efficiency was proportional to the temperature and the amount of adsorbent unlike pH increase. The highest DNOM removal rate was obtained at 35°C, pH 4, and an adsorbent amount of 0.8 g/L. Optimum contact time for batch studies was 60 min at equilibrium. Correlation constants (r) of Langmuir and Freundlich isotherms were 0.8905 and 0.9739, respectively. Based on the Freundlich isotherm, the highest adsorption capacity (qmax) obtained was 2.44 and 6.01 mg DNOM/g GAC for raw and enriched water, respectively. At a further stage, the effects of adsorbent amount, bed depth, empty bed contact time, and organic loading on removal performance were investigated in the rapid small‐scale column test (RSSCT) columns. 53 and 78% DNOM removal rates in raw water and enriched water, respectively, were sufficient to meet the targeted effluent concentration of 1 mg DNOM/L in GAC adsorption columns. It was determined that 15 adsorption columns with dimensions of 7 m height, 4.33 m diameter, and 22 days of operation cycle were required to remove DNOM from raw water at the design capacity of the facility. This article is protected by copyright. All rights reserved
102. 题目: Assessing microbial residues in soil as a potential carbon sink and moderator of carbon use efficiency
作者: Kevin Geyer, Jörg Schnecker, A. Stuart Grandy, Andreas Richter, Serita Frey
摘要: A longstanding assumption of glucose tracing experiments is that all glucose is microbially utilized during short incubations of ≤2 days to become microbial biomass or carbon dioxide. Carbon use efficiency (CUE) estimates have consequently ignored the formation of residues (non-living microbial products) although such materials could represent an important sink of glucose that is prone to stabilization as soil organic matter. We examined the dynamics of microbial residue formation from a short tracer experiment with frequent samplings over 72 h, and conducted a meta-analysis of previously published glucose tracing studies to assess the generality of these experimental results. Both our experiment and meta-analysis indicated 30–34% of amended glucose-C ( 13 C or 14 C) was in the form of residues within the first 6 h of substrate addition. We expand the conventional efficiency calculation to include residues in both the numerator and denominator of efficiency, thereby deriving a novel metric of the potential persistence of glucose-C in soil as living microbial biomass plus residues (‘carbon stabilization efficiency’). This new metric indicates nearly 40% of amended glucose-C persists in soil 180 days after amendment, the majority as non-biomass residues. Starting microbial biomass and clay content emerge as critical factors that positively promote such long term stabilization of labile C. Rapid residue production supports the conclusion that non-growth maintenance activity can illicit high demands for C in soil, perhaps equaling that directed towards growth, and that residues may have an underestimated role in the cycling and sequestration potential of C in soil.
103. 题目: Using loose nanofiltration membrane for lake water treatment: A pilot study
期刊: Frontiers of Environmental Science & Engineering
作者: Danyang Liu, Johny Cabrera, Lijuan Zhong, Wenjing Wang, Dingyuan Duan, Xiaomao Wang, Shuming Liu, Yuefeng F. Xie
摘要: Nanofiltration (NF) using loose membranes has a high application potential for advanced treatment of drinking water by selectively removing contaminants from the water, while membrane fouling remains one of the biggest problems of the process. This paper reported a seven-month pilot study of using a loose NF membrane to treat a sand filtration effluent which had a relatively high turbidity (∼0.4 NTU) and high concentrations of organic matter (up to 5 mg/L as TOC), hardness and sulfate. Results showed that the membrane demonstrated a high rejection of TOC (by<90%) and a moderately high rejection of two pesticides (54%–82%) while a moderate rejection of both calcium and magnesium (∼45%) and a low rejection of total dissolved solids (∼27%). The membrane elements suffered from severe membrane fouling, with the membrane permeance decreased by 70% after 85 days operation. The membrane fouling was dominated by organic fouling, while biological fouling was moderate. Inorganic fouling was mainly caused by deposition of aluminum-bearing substances. Though inorganic foulants were minor contents on membrane, their contribution to overall membrane fouling was substantial. Membrane fouling was not uniform on membrane. While contents of organic and inorganic foulants were the highest at the inlet and outlet region, respectively, the severity of membrane fouling increased from the inlet to the outlet region of membrane element with a difference higher than 30%. While alkaline cleaning was not effective in removing the membrane foulants, the use of ethylenediamine tetraacetate (EDTA) at alkaline conditions could effectively restore the membrane permeance.
104. 题目: Testing the reliable proxies to understand the mid-Holocene climate variability records from Chandratal lake, Western Himalayas
期刊: Quaternary International
作者: Monica Sharma Shamurailatpam, Om Kumar, A.L. Ramanathan
摘要: Chandratal lake (32°28′30.65″ N 77°37′1.42″ E) located at the junction of Indian Summer Monsoon and Westerlies give an opportunity to investigate the relationship between monsoon, Amino acids, Biogenic silica and Organic carbon. Here, we used multi-proxy (Amino acids, Biogenic silica, grain size and total organic carbon) to reconstruct mid-Holocene climate variability. Our proxy records well capture the changes in monsoon patterns, linking with Holocene climate optimum (HCO) during the ∼6344- 5821 cal BP. The sediment profile begins with a wetter and moist climate mostly from the terrestrial environment inputs, corresponding to the warm Holocene Climate Optimum (HCO) period (∼6344 - 5821 cal yr BP). A stable condition of the geochemical proxies during ∼5821–3780 cal yr BP reveals a shifting of a moisture source, catchment stability and cold/dry climate in correspondence with reduced precipitation. The period from ∼3780 to 2129 cal yr BP, follows a gradual increase of organic matter deposition and supported with an elevated atomic C/N ratio of 13.1 (mean value). Further association of organic matter with the coarser grain particles, suggesting a wetter climate from increasing runoff which is in correlation with the reinforcement of the precipitation during this time interval. From ∼2129 to 696 cal yr BP, reduced precipitation/dry condition was observed with a shift in the autochthonous production of organic matter (C/N ratio of 8.91). Increase in BSi content suggests an ameliorated climate at this interval; however, the lower organic matter content (mean, 1.79%) and shift in the correlation of organic matter from coarse grains to finer grain size, suggesting little contributions from the terrestrial activities favouring the dry environment and abundant diatoms growth. The paleoenvironmental variations illustrate in the study is comparable to other findings recorded in the Himalayan region.
105. 题目: Rates and Dynamics of Mercury Isotope Exchange between Dissolved Elemental Hg(0) and Hg(II) Bound to Organic and Inorganic Ligands
期刊: Environmental Science & Technology
作者: Quanying Wang, Lijie Zhang, Xujun Liang, Xiangping Yin, Yaoling Zhang, Wang Zheng, Eric M. Pierce, Baohua Gu
摘要: Mercury (Hg) isotope exchange is a common process in biogeochemical transformations of Hg in the environment, but it is unclear whether and at what rates dissolved elemental Hg(0)aq may exchange with divalent Hg(II) bound to various organic and inorganic ligands in water. Using enriched stable isotopes, we investigated the rates and dynamics of isotope exchange between 202Hg(0)aq and 201Hg(II) bound to organic and inorganic ligands with varying chemical structures and binding affinities. Time-dependent exchange reactions were followed by isotope compositional changes using both inductively coupled plasma mass spectrometry and Zeeman cold vapor atomic absorption spectrometry. Rapid, spontaneous isotope exchange (<1 h) was observed between 202Hg(0)aq and 201Hg(II) bound to chloride (Cl–), ethylenediaminetetraacetate (EDTA), and thiols, such as cysteine (CYS), glutathione (GSH), and 2,3-dimercaptopropanesulfonic acid (DMPS) at a thiol ligand-to-Hg(II) molar ratio of 1:1. Without external reductants or oxidants, the exchange resulted in transfer of two electrons and redistribution of Hg isotopes bound to the ligand but no net changes of chemical species in the system. However, an increase in the ligand-to-Hg(II) ratio decreased the exchange rates due to the formation of 2:1 or higher thiol:Hg(II) chelated complexes, but had no effects on exchange rates with 201Hg(II) bound to EDTA or Cl–. The exchange between 202Hg(0)aq and 201Hg(II) bound to dissolved organic matter (DOM) showed an initially rapid followed by a slower exchange rate, likely resulting from Hg(II) complexation with both low- and high-affinity binding functional groups on DOM (e.g., carboxylates vs bidentate thiolates). These results demonstrate that Hg(0)aq readily exchanges with Hg(II) bound to various ligands and highlight the importance of considering exchange reactions in experimental enriched Hg isotope tracer studies or in natural abundance Hg isotope studies in environmental matrices. The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.est.0c06229. ICP-MS quantification of Hg isotopes; Zeeman CVAAS analysis of purgeable Hg(0); certified purities and impurities of the enriched Hg isotopes 201Hg and 202Hg; elemental composition and characteristics of dissolved organic matter (DOM); list of experiments and experimental conditions used in isotope exchange reactions; QA/QC summary for Hg analyses by ICP-MS; molecular structure of organic ligands and their binding stability constants with Hg(II); speciation calculations of Hg(II) complexes with thiol ligands in 10 mM NaCl; determination of potential oxidation of 202Hg(0)aq or reduction of 201Hg(II) in 10 mM NaCl; determination of potential interactions between 202Hg(0)aq and thiol ligands or DOM; determination of purgeable Hg(0) isotopes following isotope exchange reactions between 202Hg(0)aq and 201Hg(II) bound to thiol ligands; recovery and mass balance analyses during isotope exchange reactions between 202Hg(0)aq and 201Hg(II) bound to thiol ligands; ICP-MS determination of nonpurgeable Hg(II) in solution following isotope exchange reactions between 202Hg(0)aq (12.5 nM) and 201Hg(II) (25 nM) bound to organic or inorganic ligands; determination of purgeable Hg(0) isotope concentrations, Hg recovery, and mass balance following isotope exchange reactions between 202Hg(0)aq and 201Hg(II) bound to thiol ligands and EDTA; and determination of purgeable Hg(0) isotope concentrations (nM), Hg recovery, and mass balance following isotope exchange reactions between 202Hg(0)aq and 201Hg(II) bound to SR-DOM or EFPC–DOM (PDF) This article has not yet been cited by other publications.
106. 题目: Variation in concentration and sources of black carbon in a megacity of China during the COVID‐19 pandemic
期刊: Geophysical Research Letters
作者: Liang Xu, Jian Zhang, Xin Sun, Shengchen Xu, Meng Shan, Qi Yuan, Lei Liu, Zhenhong Du, Dantong Liu, Da Xu, Congbo Song, Bowen Liu, Gongda Lu, Zongbo Shi, Weijun Li
摘要: Black carbon (BC) not only warms the atmosphere but also affects human health. The nationwide lockdown due to the COVID‐19 pandemic led to a major reduction in human activity during the past thirty years. Here, the concentration of BC in the urban, urban‐industry, suburb, and rural areas of a megacity Hangzhou were monitored using a multi‐wavelength Aethalometer to estimate the impact of the COVID‐19 lockdown on BC emissions. The citywide BC decreased by 44% from 2.30 μg/m3 to 1.29 μg/m3 following the COVID‐19 lockdown period. The source apportionment based on the Aethalometer model shows that vehicle emission reduction responded to BC decline in the urban area and biomass burning in rural areas around the megacity had a regional contribution of BC. We highlight that the emission controls of vehicles in urban areas and biomass burning in rural areas should be more efficient in reducing BC in the megacity Hangzhou.
107. 题目: Dissolved organic nitrogen cycling in the South China Sea from an isotopic perspective
期刊: Global Biogeochemical Cycles
作者: Run Zhang, Xingchen T. Wang, Haojia Ren, Jie Huang, Min Chen, Daniel M. Sigman
摘要: Dissolved organic nitrogen (DON) is the dominant form of fixed nitrogen in most of the low and mid‐latitude ocean surface. Here, we report measurements of DON isotopic composition (δ15N) from the west South China Sea, with the goal of providing new insight into DON cycling. The concentration of DON in the surface ocean is correlated (r=0.70, p<0.0001) with chlorophyll a concentration, indicating DON production in these surface waters. The concentration and δ15N of DON fall in a relatively narrow range in the surface ocean (4.6±0.1 μM and 4.3±0.2‰ vs. air, respectively; ±SD), similar to other ocean regions. The mean DON δ15N above 50 m (4.5±0.3‰) is similar to the δ15N of nitrate in the shallow subsurface (i.e. immediately below the euphotic zone; 4.6±0.2‰) but is higher than the δ15N of suspended particles in the surface ocean (~2.3‰). This set of isotopic relationships has been observed previously (e.g., in the oligotrophic North Atlantic and North Pacific) and can be explained by the cycling of N between PON, DON, and ammonium, in which an isotope effect associated with DON degradation preferentially concentrates 15N in DON. Consistent with this view, a negative correlation (r=0.70) between the concentration and the δ15N of DON is observed in the upper 75 m, suggesting an isotope effect of ~4.9±0.4‰ for DON degradation. Comparing the DON δ15N data from the SCS with other regions, we find that the δ15N difference between euphotic zone DON and shallow subsurface nitrate δ15N (Δδ15N(DON‐NO3)) rises from ocean regions of inferred net DON production to regions of net DON consumption, with the SCS representing an intermediate case.
108. 题目: Coastal hypoxia and eutrophication as key controls on benthic release and water column dynamics of iron and manganese
期刊: Limnology and Oceanography
作者: Wytze K. Lenstra, Martijn Hermans, Marie J.M. Séguret, Rob Witbaard, Silke Severmann, Thilo Behrends, Caroline P. Slomp
摘要: Continental shelves are a major source of iron (Fe) and manganese (Mn) to marine waters. Here, we investigate controls on benthic release of Fe and Mn and the impact on the water column in the Baltic Sea. We find high in situ benthic release rates of dissolved Fe and Mn at seasonally hypoxic sites (bottom water oxygen between 0–63 μmol L−1) receiving high inputs of organic matter. We find that benthic Fe and Mn release is sensitive to bottom water oxygen concentrations. Benthic Fe release is likely additionally controlled by Fe–sulfur redox chemistry in the surface sediment. For Mn, benthic release correlates positively with Mn oxide availability in the surface sediment. Benthic release contributes to high dissolved Fe and Mn concentrations in the water column and is amplified by repeated cycling of Fe and Mn between the sediment and overlying water through benthic release, oxidation in the water column, deposition as metal oxides, followed by reductive dissolution. Most water column Fe (∼ 80%) is present in particulate form near the seafloor. In contrast to Fe, a large percentage of the Mn remains dissolved (∼ 50%). We show that easily reducible Fe and Mn oxides are key forms of particulate Fe and Mn in suspended matter. The Baltic Sea represents a highly eutrophic, low oxygen end‐member when compared to other modern coastal systems. Our results imply that, upon continued eutrophication and deoxygenation of the coastal ocean, benthic release of dissolved Fe and Mn from continental shelves could become greater than previously thought.
109. 题目: Dispersed Ground Ice of Permafrost Peatlands: Potential Unaccounted Carbon, Nutrient and Metal Sources
作者: Artem G. Lim, Sergey V. Loiko, Daria M. Kuzmina, Ivan V. Krickov, Liudmila S. Shirokova, Sergey P. Kulizhsky, Sergey N. Vorobyev, Oleg S. Pokrovsky
摘要: The physical and chemical consequences of massive ground ice (wedges) melt upon permafrost thaw is one of the central issues of environmental research linked to climate warming in the Arctic. Little is known about the chemical properties of dispersed ground ice abundant throughout permafrost peatlands that can easily melt with increasing active layer thickness (ALT). This is especially pertinent in continental lowlands, that account for sizeable areas of the Arctic, and contain high amount of organic carbon in both solid (peat) and liquid (porewater) phases. Here we studied 8 peat cores (0-130 cm depth)—comprised of porewater from the active layer (0-45 cm) as well as ice dispersed in frozen peat (40-130 cm)—across a latitudinal profile of Western Siberia Lowland (WSL) extending from discontinuous into continuous permafrost zones. Dissolved Organic Carbon (DOC), alkali and alkaline-earth metals (Ca, Mg, Sr, Ba, Li, Rb, Cs), sulfate, phosphorus, some trace elements (Al, Fe, Mn, Zn, Ni, Co, V, As, Y, REE, Zr, Hf, U) were sizably [more than 3 times] enriched in peat ice compared to peat porewaters from the active layer. In most sampled cores, there was a local maximum of strong enrichment (up to factors between 14 and 58) in DOC, P, Ca, Mg, Mn, Fe, Sr, As located 30-50 cm below the active layer. This maximum likely occurred due to solute concentration during full freezing of the soil column during winter. There was a sizable correlation between DOC, Al, Fe and other major and trace element concentrations that suggests strong control of organic complexes and organo-mineral (Al, Fe) colloids on element migration throughout the peat profile. The pool of C, major cations and trace metals in peat ice (40-130 cm) was approximately 3 to 55 times higher than the pool of these elements in porewaters from the active layer (0-40 cm). A 1-m increase of the ALT over the next 100 years is capable of mobilizing 58±38 Tg of DOC from soil ice into the rivers and lakes of the WSL latitudinal belt (63-67 °N). This fast lateral export of C (3.7±2.7 t C km-2 y-1) may double current C yields in WSL rivers (3.4±1.3 t C km-2 y-1). A strong increase (150 to 200 %) in riverine export of Zn, P and Cs may also occur while other micronutrients (Fe, Ni, Co, Ba, Mo, Rb) and toxicants (Cd, As, Al) may be affected to a lesser degree (20 to 30 % increase). We propose a global peat ice inventory in permafrost regions is essential for assessing the consequenaces of permafrost thaw on surface aquatic systems.
110. 题目: Effects of plastic mulch film residues on soil-microbe-plant systems under different soil pH conditions
作者: Yin Liu, Qing Huang, Wen Hu, Jiemin Qin, Yingrui Zheng, Junfeng Wang, Qingqing Wang, Yuxin Xu, Genmao Guo, Shan Hu, Li Xu
摘要: Plastic mulch film residues (PMFR) accumulated throughout mulching years can result in serious environmental problems, especially in hotter areas with frequent farming (e.g. the tropics). The effects of long-term mulching on the soil-microbe-plant system, however, are largely unknown. As mulching years is positively correlated with PMFR concentrations, we used a controlled pot experiment to investigate the effects of mulching years (20a: The concentration of PMFR is about 2 g kg−1, 60a: About 6 g kg−1) on rice growth, rhizosphere bacterial communities, and soil organic carbon (SOC) under different soil pH conditions. Mulching years reduced rice growth; 20a showed more negative effects than 60a on rice tillers number and biomass. PMFR changed the composition, diversity, and metabolic function of the rhizosphere bacterial communities. The content of SOC decreased as mulching residues increased; total organic carbon (TOC), soil organic matter (SOM), Fn (355), and humification index (HIX) declined by 30.24%, 55.97%, 59.74%, and 70.24%, respectively. Furthermore, significant correlations between bacterial communities and SOC were observed in the soil-microbe-plant system. PMFR showed stronger negative effects on rice growth in acidic soil (pH 4.5); however, in basic soil (pH 8.5), there were stronger variations within the bacterial communities and a more significant decline in SOC than acidic soil (pH 4.5). The results of this study are expected to provide theoretical references for understanding of the effects of PMFR on agroecosystems and preventing and controlling plastic pollution.
111. 题目: Chromophoric dissolved organic matter in inland waters: present knowledge and future challenges
期刊: Science of The Total Environment
作者: Yunlin Zhang, Lei Zhou, Yongqiang Zhou, Liuqing Zhang, Xiaolong Yao, Kun Shi, Erik Jeppesen, Qian Yu, Weining Zhu
摘要: Chromophoric dissolved organic matter (CDOM) plays an important role in the biogeochemical cycle and energy flow of aquatic ecosystems. Thus, systematic and comprehensive understanding of CDOM dynamics is critically important for aquatic ecosystem management. CDOM spans multiple study fields, including analytical chemistry, biogeochemistry, water color remote sensing, and global environmental change. Here, we thoroughly summarize the progresses of recent studies focusing on the characterization, distribution, sources, composition, and fate of CDOM in inland waters. Characterization methods, remote sensing estimation, and biogeochemistry cycle processes were the hotspots of CDOM studies. Specifically, optical, isotope, and mass spectrometric techniques have been widely used to characterize CDOM abundance, composition, and sources. Remote sensing is an effective tool to map CDOM distribution with high temporal and spatial resolutions. CDOM dynamics are mainly determined by watershed-related processes, including rainfall discharge, groundwater, wastewater discharges/effluents, and biogeochemical cycling occurring in soil and water bodies. We highlight the underlying mechanisms of the photochemical degradation and microbial decomposition of CDOM, and emphasize that photochemical and microbial processes of CDOM in inland waters accelerate nutrient cycling and regeneration in the water column and also exacerbate global warming by releasing greenhouse gases. Future study directions to improve the understanding of CDOM dynamics in inland waters are proposed. This review provides an interdisciplinary view and new insights on CDOM dynamics in inland waters.
112. 题目: Degradation of anthraquinone dye reactive blue 19 using persulfate activated with Fe/Mn modified biochar: Radical/non-radical mechanisms and fixed-bed reactor study
期刊: Science of The Total Environment
作者: Yue Qiu, Qian Zhang, Zhihao Wang, Bin Gao, Zixi Fan, Meng Li, Huiru Hao, Xiaonan Wei, Min Zhong
摘要: In this study, a heterogeneous activator was prepared via the Fe/Mn modification of sludge-derived biochar (Fe/MnBC) to achieve high-efficiency activation of persulfate (PS) for reactive Blue 19 (RB19) degradation. The morphologies and chemical states of Fe/MnBC were examined by various characterizations. A comprehensive assessment was conducted to reveal the effects of biochar preparation conditions and system reaction conditions. According to the results of scavenger quenching experiments and electron paramagnetic resonance (EPR) testing, the mechanisms of Fe/MnBC combined PS system on RB19 degradation were proposed, including radical and non-radical mechanisms. The formation and involvement of sulfate radical (SO4.-), hydroxyl radical (OH·), and singlet oxygen (1O2) were proved in this system, and Fe(IV)/Mn(VII) was also speculated to participate in the non-radical degradation process. These findings give a new insight into the mechanisms of PS activated by metal-biochar composite. Besides, fixed-bed reactor (FBR) experiments indicated that the Fe/MnBC has considerable PS activation potential for dyes removal. The degradation process was further modeled by the central composite design (CCD-RSM) and artificial neural networks (ANN). The statistical metrics and prediction indicated that the prediction results of ANN model were better than CCD-RSM model, and the ANN model could perfectly predict the reaction process of Fe/MnBC FBR for engineering applications.
113. 题目: The legacy of acidic deposition controls soil organic carbon pools in temperate forests across the Czech Republic
期刊: EUROPEAN JOURNAL OF SOIL SCIENCE
作者: Tomáš Chuman, Filip Oulehle, Kateřina Zajícová, Jakub Hruška
摘要: Temperate forest ecosystems store most of the organic carbon in soils (SOC), and changes in the soil carbon stock due to climate change or land management can potentially have a large influence on carbon balance. The most important factors controlling the SOC pool on a global scale are generally agreed upon; however, estimations of SOC pools differ significantly among studies on regional and local scales due to different sampling protocols and local scale variability. This study evaluates the SOC pool in the forest floor and mineral soil sampled down to a depth of 80 cm in 14 forested catchments with variable environmental conditions and soil acidification and eutrophication legacies, and determines best explanatory variables of the SOC pool. The average SOC pool of 34 t/ha measured in the forest floor (O horizon) was best explained by measures of historical S deposition (i.e. soil acidification legacy) and forest type (conifer vs. broadleaf forest). An average total SOC pool of 132 t/ha, combining both the carbon pool in the mineral soil down to 80 cm and the carbon pool in forest floor, was best explained solely by elevation, which reflects temperature and precipitation gradients. However, when considering the coupled SOC pool in the forest floor and upper half of the sampled mineral soil (down to 40 cm), natural environmental factors were outweighed by anthropogenic ones (soil acidification legacy and forest type). This has important implications for understanding potential SOC pool changes under ongoing global climate change, especially in regions currently or historically affected by soil acidification caused by acid deposition. Acidification effect on the SOC accumulation and subsequent soil recovery after acidification retreat might affect carbon balance.
114. 题目: Simultaneously promoted reactive manganese species and hydroxyl radical generation by electro-permanganate with low additive ozone
期刊: Water Research
作者: Yunqian Song, Chun Zhao, Tuo Wang, Zheng Kong, Liushi Zheng, Haojie Ding, Yuanyuan Liu, Huaili Zheng
摘要: A novel water treatment process combining electrolysis, permanganate and ozone was tested in the laboratory. The combination showed synergistic effects in degrading various organic contaminants (like diclofenac, sulfamethoxazole, carbamazepine, etc.). A small amount of O3 (1 mg L−1, 60 mL min−1) significantly improved the oxidation and mineralization ability of an electro-permanganate process by generating more reactive manganese species and hydroxyl radicals. The combination required less energy consumption than comparable processes. Mechanism experiments showed that the ·OH involved was mainly generated by cathode reduction, homogeneous manganese catalysis, and heterogeneous manganese catalysis of O3 decomposition. Reactive Mn species were generated by electro-reduction, ·OH oxidation or/and O3 activation. In situ generated Mn (Ⅳ)s plays a vital role in generating ·OH and reactive Mn species. ·OH generated by O3 catalysis could transfer colloid Mn (Ⅳ)s to free Mn (Ⅴ)aq and Mn (Ⅵ) aq. And both the ·OH and RMnS played the dominant role for DCF removal. Increasing permanganate dosage, O3 concentration, the current density, Cl−, or humic acid, and decreasing the pH all enhanced the degradation of diclofenac, but the presence of PO43− or HCO3− inhibited it. Supplementing electrolysis with permanganate and O3 might be a practical, sustainable, and economical technology for treating refractory organics in natural waters.
115. 题目: Effects of oxalate and citrate on the behavior and redistribution of Cr(VI) during ferrihydrite-Cr(VI) co-precipitates transformation
作者: Peijing Yu, Fenglian Fu, Guangzhao Sun, Bing Tang
摘要: Understanding the influence of organic matters on the fate of Cr(VI) during ferrihydrite-Cr(VI) (Fh-Cr) co-precipitates transformation helps to study the retention of Cr(VI) by iron oxides in the environment. In this paper, Fh-Cr was prepared by co-precipitation and the redistribution of Cr(VI) in the oxalate or citrate system during the transformation of Fh-Cr was studied. X-ray diffraction, Fourier transform infrared spectroscopy, Transmission electron microscopy, and X-ray photoelectron spectroscopy were used to characterize Fh-Cr for aging 7 days at 70 oC. Results showed that both oxalate and citrate could hinder the release of Cr(VI) from Fh-Cr and abate the harm of Cr(VI). Oxalate improved the transformation from Fh-Cr to hematite and promoted Cr(VI) to be enfolded into the secondary minerals to further immobilize Cr at initial pH of 5.0 and 7.0, while citrate evidently reduced the release of Cr(VI) through stabilizing Fh-Cr at initial pH of 9.0. Besides, reduction of Cr(VI) by oxalate and citrate was through forming the surface complexes that promoted electron transfer from oxalate or citrate to Cr(VI), which can effectively abate the harm of Cr(VI). The findings of this study can promote understanding of the influences of organic matters on Cr(VI) immobilization during transformation of iron oxides in nature.
116. 题目: Highly improved dechlorination of 2,4-dichlorophenol in aqueous solution by Fe/Ni nanoparticles supported by polystyrene resin
作者: Zhiyong Zhang, Yibo Hu, Wenjuan Ruan, Huiying Ai, Baoling Yuan, Ming-Lai Fu
摘要: 2,4-dichlorophenol (2,4-DCP) is a typical chlorophenol that has been widely used in industrial production and caused serious pollution to the environment. In this study, the performance of Fe/Ni bimetallic nanoparticles supported on polystyrene cation exchange resin (Fe/Ni-D072) to remove 2,4-DCP was evaluated. The effects including the doping amount of Ni, the dosage of Fe/Ni-DCP, the initial concentration of 2,4-DCP, and pH value of the solution on the removal efficiency were also investigated. The results showed that when the initial concentration of 2,4-DCP was 20 mg/L and pH = 7.3, 90% of 2,4-DCP can be dechlorinated by Fe/Ni-D072 (Ni% = 30 wt%, dosage: 6.7 g/L) after 12 h reaction. The dechlorination process followed a pseudo-first-order model, and the reaction constant was 0.252 h-1. In addition, the effects of humic acid and common coexisted ions on dechlorination were studied. The results showed that humic acid with a low concentration (5 mg/L) and CO32- restrained the degradation of 2,4-DCP. The dechlorination products of 2,4-DCP were identified by HPLC and the result showed phenol was the main product with a slight amount of 2-CP as the dechlorination intermediate, and 4-CP was barely detected. These results suggest that Fe/Ni-D072 was a promising catalytic material for the removal of chlorophenol and has great application prospects in groundwater remediation.
117. 题目: Spatial changes in molecular composition of dissolved organic matter in the Yangtze River Estuary: Implications for the seaward transport of estuarine DOM
期刊: Science of The Total Environment
作者: Yuping Zhou, Ding He, Chen He, Penghui Li, Daidu Fan, Anyue Wang, Kai Zhang, Baoshan Chen, Chen Zhao, Yuntao Wang, Quan Shi, Yongge Sun
摘要: The complexity of dissolved organic matter (DOM) limits our understanding of the estuarine carbon cycle. This study combined a combination of bulk carbon isotope, optical techniques and ultra-high resolution mass spectrometry to study the spatial heterogeneity and compositional variations of DOM across a latitudinal transect of the Yangtze River Estuary (YRE). Results show that the whole section of YRE received high abundance of protein-like C4 fluorescent component (0.66 ± 0.08 R.U.) and high relative abundance of aliphatic compounds and peptides (8.28 ± 1.46%) from phytoplankton, which would contribute to the bioavailable DOM pool of the Eastern China Sea (ECS). However, multivariate analysis indicated that polycyclic aromatics and polyphenols from the Yangtze River experienced a significant decrease of 5% within the turbidity zone, creating a significant decrease of 0.08 in aromaticity index and modulating DOM content and compositions within the YRE. 1837 molecular formulae were identified to track dynamic behaviors of terrestrial DOM in the YRE. Molecular imprints showed the removal of terrestrial molecules in the turbidity zone indicated by the decrease of 753 in molecular quantity, when water masses mixing diluted the abundance of aromatic compounds. Adsorption and flocculation could serve important mechanisms to remove terrestrial DOM, promoting the burial of terrestrial DOM within estuarine sediments. Besides, some terrestrial molecular formulae were also detected in the ECS, suggesting the potential contribution of terrestrial DOM to the carbon stock of open seas after experiencing physical and photochemical transformations. This research provides a comprehensive insight into spatial variations of estuarine DOM composition, underlining the important role of estuaries in sorting and transporting DOM.
118. 题目: Adsorption and desorption of phenylarsonic acid compounds on metal oxide and hydroxide, and clay minerals
期刊: Science of The Total Environment
作者: Xiande Xie, Hefa Cheng
摘要: Adsorption and desorption of p-arsanilic acid (p-ASA) and roxarsone (ROX) on six soil minerals, including hematite (α-Fe2O3), goethite (α-FeOOH), ferrihydrite (Fe(OH)3), aluminum oxide (α-Al2O3), manganese oxide (γ-MnO2), and kaolinite, were studied, and the impact of solution matrices on their adsorption was systematically evaluated. Adsorption of p-ASA/ROX on the metal (hydro) oxide and clay minerals occurred quickly (mostly within 2 h), and could be well described by the pseudo second-order kinetic model. The apparent maximum adsorption capacities of α-Fe2O3, a-FeOOH, Fe(OH)3, α-Al2O3, γ-MnO2, and kaolinite (at an initial pH of 7.0) for p-ASA were 1.7, 0.9, 2.5, 0.08, 1.1, and 0.02 μmol/m2, while those for ROX were 1.6, 0.7, 2.4, 0.1, 0.5, and 0.05 μmol/m2, respectively. Besides adsorbing p-ASA/ROX, γ-MnO2 also caused their oxidation. Experimental results suggest that formation of inner-sphere complexes through the arsonic acid group is the primary mechanism for adsorption of p-ASA/ROX on iron (hydro)oxides and γ-MnO2, while outer-sphere complexation plays a critical role in their adsorption on α-Al2O3 and kaolinite. Adsorption of p-ASA/ROX on the metal (hydro)oxide and clay minerals was affected by solution pH, co-existing metal ions (Ca2+, Mg2+, Al3+, Cu2+, Fe3+, and Zn2+), oxyanions (H2PO4−, HCO3−, and SO42−), and humic acid. The solid-to-liquid partition coefficients of p-ASA during its desorption from α-Fe2O3, α-FeOOH, Fe(OH)3, α-Al2O3, γ-MnO2, and kaolinite were 0.47, 2.69, 4.38, 0.03, 30.4, and 0.1 L/g, while those of ROX were 0.28, 1.68, 3.48, 0.02, 4.0, and 0.02 L/g, respectively. Agricultural soils with lower contents of organic carbon exhibited higher adsorption capacities towards p-ASA/ROX, which indicates that soil minerals play a key role in the adsorption of phenylarsonic acid compounds while organic matter could have strong inhibitory effect. These findings could help better understand and predict the transport and fate of p-ASA/ROX in surface soils with low contents of organic matter.
119. 题目: Stickiness of extracellular polymeric substances on different surfaces via magnetic tweezers
期刊: Science of The Total Environment
作者: Chi-Shuo Chen, Ruei-Feng Shiu, Yu-Ying Hsieh, Chen Xu, Carlos I. Vazquez, Yujia Cui, Ian C. Hsu, Antonietta Quigg, Peter H. Santschi, Wei-Chun Chin
摘要: Organic particle dynamics in the surface ocean plays a critical part in the marine carbon cycle. Aggregation of marine organic particles drives their downward transport to support various marine organisms on their transit to the sediments. Extracellular polymeric substances (EPS) from various microbes are a major contributor to the oceanic organic particle pool. The stickiness of EPS is expected to play a determining role in the aggregation process of particles; however, stickiness parameters are usually indirectly estimated through data fitting without direct assessment. Here a magnetic tweezer method was developed to quantitatively assess the stickiness of three model EPS produced by: Amphora sp., (diatom), Emiliania huxleyi (coccolithophore), and Sagittula stellata (bacteria), under different in vitro environmental conditions (salinity or EDTA complexed cations) and surface matrices (EPS-EPS and bare glass). Our results showed the stickiness of three microbial EPS decreasing for S. stellata > E. huxleyi > Amphora sp., in line with their decreasing protein-to-carbohydrate (P/C) ratios (related to their relative hydrophobicity). The data not only emphasize the importance of hydrophobicity on EPS stickiness, but also demonstrates that salinity and the nature of the substrate surface can influence the stickiness. Furthermore, we investigated stickiness between various types of EPS, and the observed selective stickiness of EPS between species may shed light on the interactions among heterogeneous marine microorganisms. Overall, this newly developed system provides a platform to assess the EPS stickiness to advance our understanding of the aggregation and sedimentation process of organic particles that are critical for the fate of organic carbon as well as for biofilm formation and microbial colonization of surfaces in the ocean.
120. 题目: Cellulose, proteins, starch and simple carbohydrates molecules control the hydrogen exchange capacity of bio-indicators and foodstuffs
作者: A-L. Nivesse, N. Baglan, G. Montavon, G. Granger, O. Péron
摘要: Over the past several years, it has become increasingly acknowledged that Organically Bound Tritium (OBT) is the most pertinent tritium form for understanding its behavior and distribution within the biosphere. The fate of tritium actually depends on the accessibility and exchangeability of hydrogen atoms for isotopic exchanges in natural organic matter, especially in widespread biomass biomolecules like carbohydrates or proteins. The present work is therefore aimed at providing a means for improving the knowledge of tritium speciation and distribution on environmental matrices by evaluating the impact of molecular structure of various carbohydrate molecules on OBT behavior. We are thus proposing to assess the exchange capacities of hydrogen from a gas-solid isotopic exchange methodology in wheat grains, water-milfoil and apple environmental matrices using starch, cellulose/proteins and simple carbohydrates as their respective main constituents. For wheat grains, a good agreement was obtained between experimental and theoretical values as a result of the predominantly simple molecular structure of starch. For both water-milfoil and apple, the disparities between experimental and theoretical values showed the occurrence of the buried form of tritium, correlated with the 3D molecular complexity of their main constituents. The key role played by these determinant constituents on hydrogen exchange capacity could thus be experimentally demonstrated on several environmental matrices. These distinct hydrogen exchange capacities were then proven to exert an influence on the NE-OBT distribution on environmental matrix constituents, in yielding critical information to better the understanding of tritium distribution and behavior in the environment.