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13181. 题目: Microbial levan and pullulan as potential protective agents for reducing adverse effects of copper on Daphnia magna and Vibrio fischeri
文章编号: N19061106
期刊: Ecotoxicology and Environmental Safety
作者: Branka Lončarević, Marija Lješević, Marijana Marković, Ivan Anđelković, Gordana Gojgić-Cvijović, Dragica Jakovljević, Vladimir Beškoski
更新时间: 2019-06-11
摘要: Microbial polysaccharides, due to their unique physiochemical properties, have found application in the food industry, cosmetics, pharmacy and medicine. In the environment, microbes can use polysaccharides to alleviate the adverse effects of heavy metals in their close proximity. This adaptive property shows interesting potential for bioremediation. Herein, the effects of the exopolysaccharides (EPS) levan, produced by the bacterium Bacillus licheniformis NS032 and pullulan, produced by the fungus Aureobasidium pullulans CH-1 in the presence of copper (Cu2+) have been investigated for the first time on antioxidant enzyme activity, respiration and Cu2+ bioaccumulation of Daphnia magna as well as the bioluminescence of Vibrio fischeri. Both EPS decreased toxicity of Cu2+ in the acute test with D. magna. The activity of catalase (CAT) was significantly diminished after acute exposure to Cu2+ in comparison to treatments with Cu2+ and EPS, while in the prolonged acute exposure the CAT activity did not show statistically significant (P ≤ 0.05) differences between treatments with and without the EPS. According to ICP-MS results, during prolonged acute exposure of neonates, the bioaccumulation of Cu2+ in treatments without the EPS was 52.03 μg/g of biomass (wet), while in treatments with EPS, the bioaccumulation was lower by one order of magnitude. The respiration of neonates during acute exposure to Cu2+ with or without the EPS was monitored using the MicroOxymax respirometer, and the results show the EPS can positively effect the respiration. In the case of bacterial bioluminescence, the toxicity of Cu2+ decreased in treatments with EPS (30 min EC10) from 3.54 mg/L to 140.61 mg/L (levan) and 45.00 mg/L (pullulan). This study demonstrates protective effect of EPS against Cu2+ toxicity on D. magna and V. fischeri, and opens the door for further investigation of potential application of levan and pullulan in bioremediation of heavy metals and mitigation of their adverse effects in the aquatic environment.
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13182. 题目: 1,4-Dioxane cosolvency impacts on trichloroethene dissolution and sorption
文章编号: N19061105
期刊: Environmental Pollution
作者: Justin Milavec, Geoffrey R. Tick, Mark L. Brusseau, Kenneth C. Carroll
更新时间: 2019-06-11
摘要: Solvent stabilizer 1,4-dioxane, an emerging recalcitrant groundwater contaminant, was commonly added to chlorinated solvents such as trichloroethene (TCE), and the impact of co-disposal on contaminant transport processes remains uncertain. A series of batch equilibrium experiments was conducted with variations of 1,4-dioxane and TCE composition to evaluate aqueous dissolution of the two components and their sorption to aquifer sediments. The solubility of TCE increased with increasing amounts of 1,4-dioxane, indicating that 1,4-dioxane acts as a cosolvent causing solubility enhancement of co-contaminants. The solubilization results compared favorably with predictions using the log-linear cosolvency model. Equilibrium sorption coefficients (Kd and Kf) were also measured for different 1,4-dioxane and TCE compositions, and the findings indicate that both contaminants adsorb to aquifer sediments and TCE Kd values increased with increasing organic matter content. However, the Kd for TCE decreased with increases in 1,4-dioxane concentration, which was attributed to cosolvency impacts on TCE solubility. These findings further advance our understanding of the mass-transfer processes controlling groundwater plumes containing 1,4-dioxane, and also have implications for the remediation of 1,4-dioxane contamination.
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13183. 题目: Soil organo-mineral associations formed by co-precipitation of Fe, Si and Al in presence of organic ligands
文章编号: N19061104
期刊: Geochimica et Cosmochimica Acta
作者: Tamrat Wuhib Zewde, Jérôme Rose, Olivier Grauby, Emmanuel Doelsch, Clément Levard, Perrine Chaurand, Isabelle Basile-Doelsch
更新时间: 2019-06-11
摘要: Weathering of silicates supplies a range of cations (mainly Si, Al, Fe, but also Ca, Mg, Na, K, Mn) to the soil solution. There, cations can interact with charged functional groups of dissolved soil organic matter (OM). Unlike Al and Fe, Si does not directly bind to natural OM. However, the role of Si in the mechanisms of OM stabilization by coprecipitation with short range order mineral phases (SRO) may have been underestimated. The formation of coprecipitates was tested by titrating a biotite-weathering solution up to pH 5 in presence of 3,4-Dihydroxy-L-phenylalanine (DOPA) with initial (Fe+Al):C ratio ranging from 3 to 0.003. Size, crystallinity, chemical composition and the local structure of the coprecipitates were analyzed by TEM-EDX and Fe K-edge EXAFS. Coprecipitates are amorphous particles whatever the (Fe+Al):C ratio, but their size, composition and local structure were nevertheles seen to progessively vary with increasing C content. In low C samples (high (Fe+Al):C), coprecipitates were 2-40 nm in size and were dominated by Si (30 to 70%). Fe represented only 20-50% of the mineral phase and was structured in small oligomers of Fe octahedra. Around 20% of the Fe of the coprecipitates were bound to C. Converesly, in high C samples (low (Fe+Al):C), coprecipitates were 10-90 nm in size and Fe was the main component (45-70%). Fe was almost exclusively linked to OM by monomeric Fe-O-C bonds. Si (5-40%) and Al (15-35%) were able to form oligomers occluded in the Fe-OM network. In samples with intermediate C content ((Fe+Al):C=0.3), the coprecipitates had 5-200 nm size particles. We suggest these coprecipitates are structured in a loose irregular 3D network of amorphous small oligmers of Fe (25-75%), Si (15-50%), and Al (10-35%), forming an amorphous and open-structured mineral skeleton. Within this mineral network, we suggest the organic compounds are linked either by bonds with Fe and Al to the skeleton, by monomeric Fe-O-C in the porosity of the network, or by weak bonds with other OM. This conceptual model provides an alternative to the standard view that SRO-OM is formed by ferrihydrite and amorphous Al(OH)3. We suggest naming the structure “Nanosized Coprecipitates of inorganic oLIgomers with organiCs” with “nanoCLICs” as acronym. The presence of Si in the inorganic structures may have an impact not only on the amount of OM stabilized by the nanoCLICs, but in the longer term, on the persistence of the OM stabilization potential by metallic oligomers.

13184. 题目: Changes of heavy metal fractions during co-composting of agricultural waste and river sediment with inoculation of Phanerochaete chrysosporium
文章编号: N19061103
期刊: Journal of Hazardous Materials
作者: Yanrong Chen, Yaoning Chen, Yuanping Li, Yanxin Wu, Ziping Zeng, Ran Xu, Sha Wang, Hui Li, Jiachao Zhang
更新时间: 2019-06-11
摘要: The effects of Phanerochaete chrysosporium on the bioavailability of multiple heavy metals (Pb, Cd, Cu, and Zn) in river sediments were investigated by co-composting with the agricultural waste. The results showed that the Phanerochaete chrysosporium inoculation can greatly enhance the passivation on Cu, Pb and Cd during 60 days co-composting. The effects in the three metals followed the order: Cu > Cd > Pb. There were no differences for Zn whether inoculation with P. chrysosporium or not. Redundancy analysis (RDA) implied that more than 4/5 of the variation of all fractions data for all heavy metals was explained by all significant canonical axes. P. chrysosporium can change the significant parameters for each metal and enhance the explanatory power of RDA model. The inoculation can strengthen the effect of OM (organic matter) on the bioavailability of heavy metals, but weaken the contribution of pH.
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13185. 题目: HPLC-SEC-FTIR characterization of the dissolved organic matter produced by the microbial carbon pump
文章编号: N19061102
期刊: Marine Chemistry
作者: Daoud Abdou Ben Ali, Luc Tremblay
更新时间: 2019-06-11
摘要: The microbial carbon pump (MCP) concept regroups different processes that contribute to the formation of refractory dissolved organic matter (DOM) from labile substrates. In this study, long-term (1 yr) incubation experiments in fresh- and sea-waters were done with glucose as the only source of carbon for microorganisms. Bulk carbon, glucose and amino acid enantiomers analyses confirmed that glucose was transformed into microbial biomass and complex non-labile DOM. Dissolved organic carbon concentrations decreased during the first four months and then remained constant at ~20% of the initial level. After one year, the microbial DOM and DOM from natural waters were concentrated by evaporation and a low volume solid-phase extraction (SPE) that resulted in a very high (70 to 85%) extraction efficiency. These SPE-DOM samples were characterized by size-exclusion chromatography (HPLC-SEC) coupled with Fourier transform infrared spectroscopy (FTIR). These are the first HPLC-SEC-FTIR analyses of microbial DOM and of such high proportions of natural DOM. Results revealed that microbial DOM showed all the FTIR absorption bands seen in the DOM from natural waters. However, amino acids, carbohydrates, and aliphatic CH were more abundant in the microbial DOM, whereas phenols and esters were more visible in DOM from natural waters. It was difficult to identify consistent (in all samples) compositional trends according to molecular weight (MW). Cluster analyses showed that 72% of the variability in the relative absorbance for all the bands was explained by the origin and the type of the DOM extracts. The microbial DOM from freshwater had the most unique bulk composition while the microbial DOM from seawater was more similar to the DOM from natural waters. The DOM from natural fresh- and sea-waters exhibited the most similar composition when all the bands and MW are considered. The lack of consistent trends in the composition of the samples having the same origin (e.g., the two microbial DOM or the two freshwater DOM) shows the high heterogeneity and complexity of DOM, including the microbial non-labile DOM produced by the MCP. This suggests that the MCP contributes to the heterogeneity and complexity of the DOM found in natural waters.
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13186. 题目: Abiotic Formation of Dissolved Organic Sulfur in Anoxic Sediments of Santa Barbara Basin
文章编号: N19061101
期刊: Organic Geochemistry
作者: Hussain A. Abdulla, David J. Burdige, Tomoko Komada
更新时间: 2019-06-11
摘要: Sulfurization has been found to enhance organic matter preservation and petroleum formation in marine sediments. However, we do not yet have a comprehensive understanding of sulfurization mechanisms. In this study, we investigated several possible mechanisms of dissolved organic sulfur (DOS) formation in the top 4.5 m of anoxic sediments of Santa Barbara Basin (SBB), California Borderland. Using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICR-MS), we identified chemical formulas of potential dissolved organic matter (DOM) precursors to these DOS compounds. We also examined how the formulas of abiotically formed DOS changed as a function of depth across a major redox gradient.Results show that abiotic nucleophilic addition reactions involving bisulfide (HS-) and polysulfide (HSx-) are the major sulfurization pathways that form DOS in anoxic pore waters of SBB sediments. We identified 2,124 unique DOS formulas that could be generated from the addition of HS- and HSx- to 2,203 DOM formulas, and this accounted for ∼70% of all DOS formulas detected in these pore waters. Examining the DOM formulas that served as reactants in the abiotic sulfurization reactions, we found that 64% contained only carbon, hydrogen, and oxygen (CHO formulas) while the remainder (34%) included nitrogen (DON formulas). Our results revealed high reactivity toward sulfurization among many of the CHO and DON formulas that have H/C and O/C elemental ratios that overlap with those of carboxyl-rich alicyclic molecules (CRAM). This specific class of formulas could play an important role in the formation of organic sulfur compounds in sulfidic marine ecosystems, and in the formation of sulfur-containing protokerogen in marine sediments. Our results further suggest that anoxic sediments are a source of DOS compounds to the oceans.

13187. 题目: Biochar amendment effects on the activities of soil carbon, nitrogen, and phosphorus hydrolytic enzymes: a meta-analysis
文章编号: N19061001
期刊: Environmental Science and Pollution Research
作者: Leiyi Zhang, Yangzhou Xiang, Yiming Jing, Renduo Zhang
更新时间: 2019-06-10
摘要: The aim of this meta-analysis was to synthesize the effects of biochar amendment on soil enzyme activities (SEAs) related to carbon (C), nitrogen (N), and phosphorus (P) cycling. Based on 401 paired comparisons from 43 published studies, the SEAs and main influential factors were analyzed in response to biochar characteristics, soil properties, and experiment conditions. Results showed that biochar additions to soils overall increased the N- and P-cycling SEAs by 14 and 11%, respectively. The enhancement of the N- and P-cycling SEAs was mainly attributable to the microbial stimulation by biochar properties (i.e., nutrient content and porosity) and soil nutrients (e.g., soil organic C and total N). The enhancement was the most significant under the conditions with biochars produced at low temperatures and using feedstock materials with high nutrient content, and biochar applications in acidic or neutral soils, coarse or fine soils, and farmland soils. Biochar additions to soils overall reduced the C-cycling SEAs by 6.3%. The C-cycling SEAs were greatly suppressed under the conditions with low and very high biochar loads, biochars produced at high temperatures and with feedstock materials of herb and lignocellulose, and biochar applications in alkaline, fine, and forest soils. The results were mainly related to the adsorption and inhibition effects of biochars and soil properties (e.g., liming effect, high biochar porosity and aromatic C content) on fungi and the enzymes. Biochar feedstock, C/N and load, and soil total N were the main influential factors on the SEAs. The results from this study demonstrate that biochar amendment is beneficial to improving soil N and P cycling and C sequestration.

13188. 题目: An environmentally friendly surrogate method for measuring the soluble chemical oxygen demand in wastewater: use of three-dimensional excitation and emission matrix fluorescence spectroscopy in wastewater treatment monitoring
文章编号: N19060905
期刊: Environmental Monitoring and Assessment
作者: Angélique Goffin, Sabrina Guérin-Rechdaoui, Vincent Rocher, Gilles Varrault
更新时间: 2019-06-09
摘要: Gaining rapid knowledge of dissolved organic matter (DOM) proves to be decisive for wastewater treatment plant operators in efforts to achieve good treatment efficiency in light of current legislation. DOM can be monitored by application of fluorescence spectroscopy both online and in real time in order to derive an assessment of DOM oxidation potential. This work presents an eco-friendly alternative method for measuring the soluble chemical oxygen demand (COD) in raw sewage by means of three-dimensional fluorescence spectroscopy. A peak-picking approach has been developed based on a previous parallel factor analysis (PARAFAC) model dedicated to Paris raw sewage. Fluorescence spectroscopy parameters were used to obtain a good prediction model of soluble COD (r2 = 0.799; p < 0.0001; n = 80) for raw sewage. The approach employed in this study serves as a guideline for purposes of implementing online wastewater monitoring and conducting environmentally friendly soluble COD measurements in the laboratory.

13189. 题目: Adaptation of semi-continuous anaerobic sludge digestion to humic acids
文章编号: N19060904
期刊: Water Research
作者: Ji Li, Xiaodi Hao, Mark C.M. van Loosdrecht, Jinglun Yu, Ranbin Liu
更新时间: 2019-06-09
摘要: Anaerobic digestion (AD) is a technology for recovering chemical energy as methane from excess sludge/waste. Unfortunately, humic acids (HA) contained in excess sludge can have the effects of inhibiting the efficiency of energy conversion. Based on a batch experiment, the impact of HA on a semi-continuous AD process was sequentially investigated, with the impact on the associated enzymes and microorganisms being measured. The results of this semi-continuous experiment indicate that the inhibition of the microbial community increased with an increased HA:VSS ratio. Long-term cultivation did not result in the adaption of methane production to the presence of HA. Moreover, at HA:VSS = 20%, the strongest inhibition (74.3%) on energy conversion efficiency was observed in the semi-continuous experiment, which was two-fold higher than that recorded in the batch experiment. This is attributed to serious and irreversible inhibition of both acidogenic and methanogenic microorganisms, as well as the physical-chemical reactions between HA and the associated enzymes which, it was concluded, were the dominant mechanisms of inhibition in the batch experiment.
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13190. 题目: Mitigative effects of natural and model dissolved organic matter with different functionalities on the toxicity of methylmercury in embryonic zebrafish
文章编号: N19060903
期刊: Environmental Pollution
作者: Dan Li, Lingtian Xie, Michael J. Carvan, Laodong Guo
更新时间: 2019-06-09
摘要: Dissolved organic matter (DOM) occurs ubiquitously in aquatic environments and plays an intrinsic role in altering the chemical speciation and toxicity of methylmercury (MeHg). However, interactions between MeHg and natural DOM remain poorly understood, especially at the functional group level. We report here the mitigative effects of three natural organic matter (NOM) and five model-DOM under different concentrations (0, 1, 3, 10, 30 and 100 mg-C/L) on the toxicity of MeHg in embryonic zebrafish (<4 h post-fertilization, hpf). NOM are those from the Mississippi River, Yukon River, and Suwannee River, while model-DOM include those containing thiosalicylic acid, L-glutathione, dextran, alginic acid, and humic acid. We selected a MeHg concentration (100 n-mol/L) that reduces the survival rate of embryos at 24 hpf by 18% and increases malformations at 72 and 96 hpf. In the presence of DOM, however, the malformation rates induced by MeHg can be mitigated to a different extent depending on DOM concentrations, specific functional groups, and/or specific components. Model DOM with aromatic thiols was the most effective at mitigating the effects of MeHg, followed by L-glutathione, carbohydrates, and humic acid. NOM also mitigated the toxicity of MeHg dependent on their composition and/or effective DOM components as characterized by fluorescence excitation-emission matrix techniques. Specifically, humic-like DOM components are more effective in reducing the MeHg toxicity in the embryonic zebrafish compared to protein-like components. Further studies are needed to elucidate the interactions between DOM and MeHg and the mitigative mechanisms at the molecular level.
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13191. 题目: Influence of nanoplastic surface charge on eco-corona formation, aggregation and toxicity to freshwater zooplankton
文章编号: N19060902
期刊: Environmental Pollution
作者: Juan Saavedra, Serge Stoll, Vera I. Slaveykova
更新时间: 2019-06-09
摘要: Concerns about possible environmental implications of nano- and micro-plastics are continuously raising. Hence, comprehensive understanding of their behaviour, bioaccumulation and toxicity potential is required. Nevertheless, systematic studies on their fate and possible effects in freshwaters, as well as the influence of particle-specific and environmental factors on their behaviour and impacts are still missing. The aims of the present study are thus two-fold: (i) to examine the role of the surface charge on nanoplastic stability and acute effects to freshwater zooplankton; (ii) to decipher the influence of the refractory natural organic matter (NOM) on the nanoplastic fate and effects. Amidine and carboxyl-stabilized polystyrene (PS) spheres of 200 nm diameter characterized by opposite primary surface charges and neutral buoyancy were selected as model nanoplastics. The results demonstrated that the surface functionalization of the polystyrene nanoplastics controls their aggregation behaviour. Alginate or Suwannee River humic acid (SRHA) modified significantly the surface charge of positively-charged amidine PS nanoplastic and the aggregation state, while had no significant influence on the negatively-charged carboxyl PS nanoplastic. Both amidine and carboxyl PS nanoplastics were ingested by the zooplankton and concentrated mainly in the gut of water flea Daphnia magna and larvae Thamnocephalus platyurus, and the stomach of rotifer Brachionus calyciflorus. Amidine PS nanoplastic was more toxic than carboxyl one. The toxicity decreased in the order D. magna (48 h -immobilization) > B. calyciflorus (24 h - lethality) > T. platyurus (24 h - lethality). Alginate or SRHA reduced significantly the toxicity of both amidine and carboxyl PS nanoplastics to the studied zooplankton representatives. The implications of this laboratory study findings to natural environment were discussed.
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13192. 题目: Assessment of nutrient removal and microbial population dynamics in a non-aerated vertical baffled flow constructed wetland for contaminated water treatment with composite biochar addition
文章编号: N19060901
期刊: Journal of Environmental Management
作者: Fanchen Meng, Lijuan Feng, Haojie Yin, Kongqing Chen, Guanghui Hu, Guangfeng Yang, Jiaheng Zhou
更新时间: 2019-06-09
摘要: A novel composite biochar (NCB) was produced from the pyrolysis of co-fermentation products of sewage sludge, food wastes and rice straw, and exhibited higher nitrogen and phosphorus adsorption capacity due to the larger surface area (14.7 m2 g−1) and higher Ca content (51753.7 mg kg−1) than single rice straw biochar. The addition of NCB was then investigated in a non-aerated vertical baffled flow constructed wetland (VBFCW) for contaminated water treatment. The VBFCW with NCB addition significantly improved CODMn, NH4+-N, TN and TP removal efficiencies of 83.3 ± 5.3%, 95.9 ± 3.4%, 28.0 ± 4.0% and 59.5 ± 11.8%, respectively, at a hydraulic retention time (HRT) of 3 d. In addition, the TN and TP removal rates at a decreased HRT of 2 d were much higher than those at an HRT of 3 d without NCB addition. The presence of NCB in the VBFCW system enhanced nutrient adsorption and improved the enrichment of bacteria for organic and nitrogen removal mainly including the genera Bacillus and Lactococcus.

13193. 题目: Differences in chemical composition of PM2.5 emissions from traditional versus advanced combustion (semi-gasifier) solid fuel stoves
文章编号: N19060811
期刊: Chemosphere
作者: Alexandra Lai, Ming Shan, Mengsi Deng, Ellison Carter, Xudong Yang, Jill Baumgartner, James Schauer
更新时间: 2019-06-08
摘要: A common strategy to improve indoor air quality in households burning coal and biomass is the introduction of advanced combustion solid fuel stoves, which can use existing fuels yet emit fewer pollutants. Chemical composition of PM is affected by numerous combustion parameters, but is often not considered in energy transitions, despite varying toxicity among chemical components. We analyzed PM2.5 emissions from combustion of solid fuels (coal, wood, and straw; whole and pelletized) in a variety of stoves (cookstoves and heating stoves; traditional and semi-gasifier, including forced versus natural draft and fixed versus reciprocating grate). To assess the effects of fuel and stove type on PM2.5 composition, we measured elemental carbon (EC), organic carbon (OC), water-soluble OC, water-soluble inorganic ions (e.g. SO42−, Cl, K+), and organic molecular markers. PM2.5 emissions from traditional stoves were mostly carbonaceous: 76–90% organic matter (OM), 5–6% EC, and less than 2% inorganic ions. In contrast, semi-gasifier stoves emitted more inorganic PM2.5: on average, ions comprised 65%, 9% was OM, and 4% was EC. Within the semi-gasifier cookstoves, forced-draft cookstove emissions had lower OM (1–3%) and higher ion concentrations (84–88%) than the natural-draft cookstove (5–14% OM, 30–83% ions). Levoglucosan was detected in PM2.5 from combustion of wood in the traditional cookstove and biomass pellets in the natural-draft semi-gasifier cookstove, but not from wood pellets in the forced-draft semi-gasifier cookstove. Across a range of different fuels and stoves, stove type influenced emitted PM composition more than fuel type, underscoring the impact of combustion conditions on PM chemical composition.
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13194. 题目: Isopycnal processes allow for summertime heterotrophy despite net oxygen accumulation in the lower‐euphotic zone of the western North Atlantic subtropical gyre
文章编号: N19060810
期刊: Global Biogeochemical Cycles
作者: Haidi Chen, Galen A. McKinley
更新时间: 2019-06-08
摘要: In the oligotrophic subtropical gyre of the North Atlantic, the processes that allow for an imbalance between annual biological productivity and organic carbon export have been sought for decades. We use biogeochemical data from profiling floats and 26‐years bottle samples off Bermuda to provide the first evidence for a mechanism that allows for heterotrophy in the presence of oxygen accumulation in the lower‐euphotic zone (50‐100m) during the stratified season. After the spring bloom, surface waters that are enriched in oxygen and organic matter, but low in nitrate, are subducted and transported along the seasonal isopycnals that progressively displace downward. Due exclusively to this downward displacement, a positive 50‐100m depth‐integrated O2 anomaly appears (1688±545 mmol O2 m‐2) from mid‐May to mid‐October. Neglecting this effect of isopycnal displacement would suggest an excess of biological productivity over remineralization at 50‐100m (344±330 mmol O2 m‐2). Yet, when these changes are differenced, significant along‐isopycnal oxygen consumption (‐1344±537 mmol O2 m‐2) is identified. After accounting for mixing, net biological‐driven oxygen consumption is still found (‐827±509 mmol O2 m‐2), which indicates heterotrophy. Remineralization of sinking and suspended organic matters at 50‐100m could support 90±67% of the heterotrophic demand. Our analysis also shows that the spread in the biological‐driven oxygen sink is linked to the strength of isopycnal displacement that modulates the supply of nutrients and organic matters. This along‐isopycnal transport and heterotrophy in the lower‐euphotic zone reduces carbon export at 100m, and helps to resolve previously noted imbalances between surface biological productivity and total organic carbon export.

13195. 题目: Can the increase of irrigation frequency improve the rate of water and salt migration in biochar-amended saline soil?
文章编号: N19060809
期刊: Journal of Soils and Sediments
作者: Junna Sun, Runya Yang, Jinjin Zhu, Yinghua Pan, Mao Yang, Zhenhua Zhang
更新时间: 2019-06-08
摘要: Purpose: It is difficult to leach salt into the deep layers of saline or sodic soils due to their poor permeability. The frequency of irrigation is a major factor affecting salt-leaching efficiency. Since biochar amendments are known to improve soil permeability, they may affect salt-leaching efficiency indirectly. Here, we investigated whether the increase of irrigation frequency could improve the rate of water and salt migration in biochar-amended coastal saline soil. Materials and methods: The effects of biochar amendment on the dynamics of water and salt migration in a coastal saline soil from the Yellow River Delta were monitored through soil column leaching experiments. Three different biochar levels were applied at 0% (control), 1%, and 5% (w/w), while the same irrigation amount was applied in two modes: continuous and intermittent. Results and discussion: The total duration of intermittent irrigation water vertical infiltration exceeded that of continuous irrigation. The 5% biochar treatment significantly increased the average water content in the soil profile compared with the control treatment lacking biochar. By contrast, increasing the irrigation frequency reduced the average water content in the soil profile (25.4–29.5%) when compared with continuous irrigation (27.7–31.8%). Electrical conductivity increased by 31.9–64.1% at the 60-cm soil depth for all biochar treatments under intermittent irrigation when compared with continuous irrigation. Under continuous irrigation, the 5% biochar treatment showed the earliest desalinization effect, maintaining the lowest peak value of soil salt across the different soil depths tested. Under intermittent irrigation, soil salt always peaked following each irrigation event, with its lowest peak value provided by the 5% biochar treatment at depths of 30, 45, and 60 cm (but not at 10 cm). Conclusions: Applying an intermittent irrigation to planted crops coupled to a higher biochar amendment (e.g., 5%) may improve salt-leaching efficiency in coastal saline soils. Future empirical studies are required to verify these conclusions under field conditions.

13196. 题目: Dynamics of the activated sludge in a newly-defined green bio-sorption reactor (GBR)
文章编号: N19060808
期刊: Chemical Engineering Journal
作者: Ranbin Liu, Yaqian Zhao, Wenxuan Li, Qilin Wang, Cheng Shen, Olumide Wesley Awe, Xiaodi Hao
更新时间: 2019-06-08
摘要: When upgrading an aging wastewater treatment plant (WWTP), the sludge management line is always out of consideration in terms of cost and easy-operation. This study presented the dynamics of the sludge when upgrading a conventional sequencing batch reactor (SBR) to green bio-sorption reactor (GBR) by embedding alum sludge-based constructed wetland (AlCW). The aluminum (Al(III)) content in the effluent and the resultant impact on organisms were also evaluated. The results showed that the Al(III) residues was at an acceptable level (<0.2 mg/L). The AlCW and its leachate Al(III) did not pose any detrimental impact on the activity of heterotrophic organisms and the nitrifiers whereas the activity of the polyphosphate accumulating organisms was completely suppressed and eliminated out of the reactor. In addition, the Al(III) hydroxides and natural organic matter promoted the flocculation of activated sludge flocs by complexation with the extracellular polymeric substances. As a result, the larger and compact activated sludge led to an increase of the settling velocity and the dewatering efficiency while deteriorating the sludge compressibility (sludge volume index of 150 mL/g). Interestingly, this laboratory-scale GBR was verified to be a promising alternative to upgrade the ageing WWTPs simultaneously with an improvement of the dewatering properties of the activated sludge.
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13197. 题目: Deficiencies of secondary Fe (oxy)hydroxides associated with phyllosilicates and organic carbon limit the formation of water-stable aggregates in Fe-ore tailings
文章编号: N19060807
期刊: Chemical Geology
作者: Songlin Wu, Tuan A.H. Nguyen, Yunjia Liu, Gordon Southam, Shuncai Wang, Ting-Shan Chan, Ying-Rui Lu, Longbin Huang
更新时间: 2019-06-08
摘要: The formation of water-stable, hierarchical aggregate structure is one of the critical processes in eco-engineering iron (Fe) ore tailings into soil-like medium for sustainable rehabilitation of Fe ore mine site. Through systematically comparing physical structure and mineralogical differences between Fe ore tailings' aggregates and Fe-rich native soil aggregates at a magnetite-Fe ore mine, the present study captured the microstructure, mineralogy and organic matter composition of aggregates in aged (4 years old) tailings, in comparison with those in native soils. A suite of micro-spectroscopic methods have been employed to elucidate their physical, mineralogical and morphological characteristics, including synchrotron based Fe K edge X-ray absorption fine structure spectroscopy (XAFS), and backscattered electrons (BSE)-scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). The results revealed significant differences in physical structure of aggregates in Fe ore tailings and natural soils rich in Fe, which was attributed to their different mineralogical and organic components and characteristics. Especially, it was found that the secondary Fe (oxy)hydroxides (i.e., goethite, ferrihydrite) and their interactions with Al/Si rich secondary phyllosilicates (or aluminosilicates) were required in the formation of amorphous Fe-Si-Al rich gels that acted as cementing agents for agglomerating Si-rich particles (e.g., quartz) in soil. In contrast, tailing aggregates (rich in more crystalline primary minerals such as magnetite and biotite) lacked these gels, resulting in poor stability. Comparatively, natural soil aggregates contained more recalcitrate organic carbon groups (e.g., aromatic, carboxyl and aliphatic C) than tailing aggregates, which would have also contributed to the improvement of aggregate stability through organo-mineral associations. This study has improved our understanding of key limiting geochemical factor(s) involved in the aggregation of Fe rich soils, which would provide the basis for formulating effective eco-engineering inputs to accelerate the development of soil-like structure in the Fe ore tailings for sustainable rehabilitation.

13198. 题目: Effects of crop straw and its derived biochar on the mobility and bioavailability in Cd and Zn in two smelter-contaminated alkaline soils
文章编号: N19060806
期刊: Ecotoxicology and Environmental Safety
作者: Ran Xiao, Ping Wang, Shenshen Mi, Amjad Ali, Xiangyu Liu, Yiman Li, Weidou Guan, Ronghua Li, Zengqiang Zhang
更新时间: 2019-06-08
摘要: In this study, comparative investigations on the effects of crop straw and its derived biochars on soil Cd and Zn mobility and availability were conducted. Crop straws (i.e. maize straw, rapeseed straw, and wheat straw) and their derived biochars were incubated with two contaminated alkaline soils (FX and TG soils) at 2.5% (w/w). The changes of soil properties like pH, EC, organic matter content, and dissolved organic matter content were investigated along with metal mobility, speciation distribution, and accumulation in ryegrass (Lolium multiflorum Lam.). Results indicated biochar, especially those were high in pH, enhanced soil pH (>0.2 units, p < 0.05), whereas a continuous reduction of soil pH was observed among treatments with crop straws. Both soil EC and the organic matter content increased with the application of both crop straws and biochars. In term of metals, Cd and Zn mobility were reduced with 6–14%/1–5% and 6–27%/7–15% reduction in the DTPA extractable Cd and Zn contents in TG and FX soil treatments, respectively. Moreover, distinct changes of metals in different fractions were also observed (acid soluble and reducible fraction → oxidizable fraction in straw treatments; acid soluble fraction → reducible soluble fraction in biochar amendments). Furthermore, the biological analysis revealed that the growth of ryegrass was promoted, but the accumulation of metals in ryegrass shoots was reduced, especially in MS700 treatment. Apart from the amendments, metal immobilization efficiencies were negatively correlated with the contamination status. Despite that, a higher rate of biochar application (>10%) could dramatically reduce the amount of available metal in soil extracts, except for Zn in FX soil treatments. This present work demonstrated that biochars, especially those produced at a higher temperature, are superior to crop straws to immobilize metals in soils. However, the remediation efficiencies were strongly restricted by soil pH and contamination status.
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13199. 题目: Residual chemical oxygen demand (COD) fractionation in bio-treated coking wastewater integrating solution property characterization
文章编号: N19060805
期刊: Journal of Environmental Management
作者: Cong Wei, Hengping Wu, Qiaoping Kong, Jingyue Wei, Chunhua Feng, Guanglei Qiu, Chaohai Wei, Fusheng Li
更新时间: 2019-06-08
摘要: The refractory nature of residual COD in bio-treated coking wastewater (BTCW) creates barriers for its further treatment and reclamation. It is necessary to fractionate the residual COD in BTCW associated with characterization of solution properties. In this paper, a stepwise process composed of membrane filtration, coagulation, adsorption and ozonation was proposed to fractionate residual COD in the BTCW, in which the COD was stepwise reduced to near zero. In addition, the correlation between COD and water quality indexes as well as solution properties were discussed together with a safety assessment of the water quality. Results showed that the residual COD fractionation percentage contributed by suspended solids, colloids, dissolved organics and reductive inorganic substances in the BTCW was 43.7%, 22.1%, 26.2% and 4.9%, respectively. By stepwise fractionating of these substances, the residual COD was reduced from 168.8 to 5.2 mg L−1, and the UV254 value decreased from 1.90 to 0.15 cm−1. In addition, the particle size of the dominant substances contributing to the residual COD was smaller than 450 nm. Among these substances, the hydrophobic fraction accounted for 78.66% (in the term of TOC). Three-dimensional excitation-emission matrix (3D-EEM) analysis showed that hydrophobic neutral substances (HON) were the main fluorescence constituent in the BTCW, which was highly removable by adsorption. The residual COD after adsorption was mainly composed of reductive inorganic substances. Apart from pursuit of high COD removal rates, more emphasis should be given to the removal of toxic COD. Correlations were observed between the residual COD and water quality indicators as well as solution properties, providing a guideline for optimized removal of residual COD in the BTCW. In summary, these results gave a referential information about the nature of residual COD in the BTCW for the selection of advanced treatment technologies and the management of water quality safety.
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13200. 题目: Comparison of microgels, extracellular polymeric substances (EPS) and transparent exopolymeric particles (TEP) determined in seawater with and without oil
文章编号: N19060804
期刊: Marine Chemistry
作者: Chen Xu, Wei-Chun Chin, Peng Lin, Hongmei Chen, Meng-Hsuen Chiu, Derek C. Waggoner, Wei Xing, Luni Sun, Kathleen A. Schwehr, Patrick G. Hatcher, Antonietta Quigg, Peter H. Santschi
更新时间: 2019-06-08
摘要: Extracellular polymeric substances (EPS), produced by microorganisms, are implicated for greatly influencing the fate of environmental contaminants, including oil. Transparent exopolymeric particles (TEP) are gel-like acidic polysaccharide particles that can be stained with Alcian blue, whereas Coomassie stainable particles (CSP) contain proteins and are stained with Coomassie brilliant blue. Marine microgels are reversibly formed from EPS. These terms are often used interchangeably, but they have rarely been measured simultaneously. Mesocosm and bottle experiments provided an opportunity to compare EPS, TEP, CSP and microgels in a water-accommodated fraction (WAF) of oil and seawater (control). Our results reveal that the biopolymers making up EPS, TEP and CSP consisted primarily of polysaccharides and proteins, mostly likely as proteoglycans and glycoproteins. Significant correlations were found between concentrations of TEP-C vs particulate organic carbon (POC), TEP-C vs particulate organic nitrogen (PON), TEP vs EPS, TEP vs CSP, TEP vs carbohydrates, proteins, CSP and carbohydrates, CSP vs proteins, and carbohydrates vs proteins. Chemical analysis of whole particles and colloids yielded both protein and polysaccharides concentrations higher than those in EDTA extraction, thus providing an upper limit of actual EPS contents in the particulate phase. The EPS that was electrostatically held onto particle surfaces (extractable by 1% EDTA) accounted for a minor (~4%) yet relatively constant proportion of TEP. Overall, the concentrations of the three terms ranked in the order of [gels] > [TEP] > [particulate EPS] in the water. Lastly, spectrophotometric methods have limitations in identifying complex or refractory polysaccharides, as evidenced by the comparison between NMR-quantified EPS and the total EPS determined by spectrophotometric methods. This study is the first time these terms were compared in the same sample. They provide useful information when reviewing historical TEP, CSP, EPS data collected field- and laboratory-studies, and provide linkages between them. In addition, they also demonstrate that they could provide complementary information relevant to ecosystem and flux studies.
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