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18761. 题目: Isolating organic carbon fractions with varying turnover rates in temperate agricultural soils – A comprehensive method comparison
文章编号: N18071115
期刊: Soil Biology and Biochemistry
作者: Christopher Poeplau, Axel Don, Johan Six, Michael Kaiser, Dinesh Benbi, Claire Chenu, M. Francesca Cotrufo, Delphine Derrien, Paola Gioacchini, Stephanie Grand, Edward Gregorich, Marco Griepentrog, Anna Gunina, Michelle Haddix, Yakov Kuzyakov, Anna Kühnel, Lynne M. Macdonald, Jennifer Soong, Sylvain Trigalet, Marie-Liesse Vermeire
更新时间: 2018-07-11
摘要: Fractionation of soil organic carbon (SOC) is crucial for mechanistic understanding and modeling of soil organic matter decomposition and stabilization processes. It is often aimed at separating the bulk SOC into fractions with varying turnover rates, but a comprehensive comparison of methods to achieve this is lacking. In this study, a total of 20 different SOC fractionation methods were tested by participating laboratories for their suitability to isolate fractions with varying turnover rates, using agricultural soils from three experimental sites with vegetation change from C3 to C4 22–36 years ago. Enrichment of C4-derived carbon was traced and used as a proxy for turnover rates in the fractions. Methods that apply a combination of physical (density, size) and chemical (oxidation, extraction) fractionation were identified as most effective in separating SOC into fractions with distinct turnover rates. Coarse light SOC separated by density fractionation was the most C4-carbon enriched fraction, while oxidation-resistant SOC left after extraction with NaOCl was the least C4-carbon enriched fraction. Surprisingly, even after 36 years of C4 crop cultivation in a temperate climate, no method was able to isolate a fraction with more than 76% turnover, which challenges the link to the most active plant-derived carbon pools in models. Particles with density >2.8 g cm 3 showed similar C4-carbon enrichment as oxidation-resistant SOC, highlighting the importance of sesquioxides for SOC stabilization. The importance of clay and silt-sized particles (<50 μm) for SOC stabilization was also confirmed. Particle size fractionation significantly outperformed aggregate size fractionation, due to the fact that larger aggregates contain smaller aggregates and organic matter particles of various sizes with different turnover rates. An evaluation scheme comprising different criteria was used to identify the most suitable methods for isolating fractions with distinct turnover rates, and potential benefits and trade-offs associated with a specific choice. Our findings can be of great help to select the appropriate method(s) for fractionation of agricultural soils.

18762. 题目: Nitrogen functional gene activity in soil profiles under progressive vegetative recovery after abandonment of agriculture at the Puding Karst Critical Zone Observatory, SW China
文章编号: N18071114
期刊: Soil Biology and Biochemistry
作者: Dandan Li, Xinyu Zhang, Sophie M. Green, Jennifer A.J. Dungait, Xuefa Wen, Yuqian Tang, Zhiming Guo, Yang Yang, Xiaomin Sun, Timothy A. Quine
更新时间: 2018-07-11
摘要: At the end of the 20th century, China launched the ‘Grain-for-Green’ Project (GGP) that recommended the abandonment of low-yielding sloping farmland (>15°) prone to soil degradation by erosion, to allow recovery through natural vegetative regeneration. The effect of this policy on soil nitrogen (N) cycling, as fertilization applications are also withdrawn after abandonment, is poorly understood. A space-for-time approach was applied to investigate the responses of nitrogen functional genes (NFGs) in soil profiles (surface to bedrock) associated with progressive vegetative recovery (sloping farmland > recently abandoned sloping farmland > secondary forest > primary forest) at the Puding Karst Critical Zone Observatory in Guizhou province, southwest China. Coincident soil chemical properties (dissolved organic carbon (DOC), nitrate (NO3--N), ammonium (NH4+-N), available inorganic phosphorus (AP), soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP)) were also quantified. We found that the absolute abundance of NFGs significantly varied according to the phase of vegetation recovery, and that concentrations of AP and NO3--N were the best explanatory variables. The external N from fertilizer application promoted the absolute abundances of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in sloping farmland. The relative abundances of chiA (associated with decomposition) increased with soil depth across all vegetation recovery phases. The relative abundances of chiA and nifH (associated with N fixation) accounted for the largest proportion (58–72%) of the measured NFGs, indicating that active N-acquisition increased along the vegetation recovery gradient. The ratios of (chiA + nifH)/(AOA + AOB) and the sums of (nirK + nirS) were larger in the forest soil than those of sloping farmland and abandoned sloping farmland, implying a greater capacity for N storage potential, though accompanied by increased gas N emission potential, in the karst forest ecosystems. Our results provide a new and comprehensive understanding of soil N cycling potentials at the microscale in degraded and recovering karst ecosystems.

18763. 题目: Responses of fungal–bacterial community and network to organic inputs vary among different spatial habitats in soil
文章编号: N18071113
期刊: Soil Biology and Biochemistry
作者: Wei Zheng, Zhiyuan Zhao, Qingli Gong, Bingnian Zhai, Ziyan Li
更新时间: 2018-07-11
摘要: Interactions among the species in microbial communities are important for organic matter turnover and nutrient cycling in the soil. Their responses to organic amendments have been studied recently but the co-occurrence patterns in different spatial soil habitats such as those with different sized aggregates are still unclear. Thus, we investigated networks comprising bacteria and fungi after the application of a cover crop for 9 years. The microbial community compositions and their co-occurrence networks were examined in the whole soil and different sized soil aggregates (>0.25 mm, 0.053–0.25 mm, and <0.053 mm). The microbial community compositions and their responses to the cover crop varied in the whole soil and aggregate fractions. Network analysis in the whole soil and different sized aggregates showed that the competition between fungi and bacteria in the whole soil increased due to the annual organic material input, but the fungi–bacteria relationships varied among different sized aggregates. In particular, the competition between fungi and bacteria increased in macroaggregates but decreased in silt + clay due to organic material inputs. Thus, the co-occurrence networks determined for the fungal and bacterial communities in various soil aggregates were very different from those in the whole soil, and their responses to organic inputs also varied in different spatial habitats in the soil.

18764. 题目: Simulated nitrogen deposition favors stress-tolerant fungi with low potential for decomposition
文章编号: N18071112
期刊: Soil Biology and Biochemistry
作者: Eric W. Morrison, Anne Pringle, Linda T.A. van Diepen, Serita D. Frey
更新时间: 2018-07-11
摘要: Global changes such as atmospheric nitrogen (N) deposition can alter the structure of microbial communities, but a mechanistic understanding of the linkages between community structure and ecosystem function is lacking. Here we apply a trait-based framework to an analysis of litter fungal communities in a temperate forest exposed to >20 years simulated N addition in order to develop hypotheses regarding the mechanisms underlying community responses and resulting changes in ecosystem function. We performed metabarcoding of the total and active fungal communities and measured extracellular enzyme activity in leaf litter after it decomposed for approximately two years in a long-term simulated N deposition experiment. We found that N fertilization decreased the relative abundance of six species in the active community that were highly correlated with lignin decomposing enzyme activity. Four of these species have currently unknown taxonomic identity and should be targets for isolation and further characterization. Nitrogen fertilization also increased species richness and relative abundance of yeasts in the total community and decreased their relative activity levels, suggesting these species may be dormant or otherwise inactive. Together these responses may contribute to accumulation of organic matter in soils by favoring yeasts that are not strong enzyme producers and by disfavoring the fungal species that are most active in litter decomposition.

18765. 题目: Environmental controls on extracellular polysaccharide accumulation in a California grassland soil
文章编号: N18071111
期刊: Soil Biology and Biochemistry
作者: Kenneth A. Marchus, Joseph C. Blankinship, Joshua P. Schimel
更新时间: 2018-07-11
摘要: Areas with Mediterranean climate regimes, such as California, have cool wet winter growing seasons and hot dry summers. Summer is a time of stress for plants, yet soil microbes survive and biochemical processes continue. One mechanism soil microorganisms might use to survive drought is to produce extracellular polysaccharides (EPSac). We hypothesized that in dry soils, pools of microbial EPSac would therefore increase, but that this increase would depend on having carbon available from fresh plant inputs. We manipulated plant cover and dry season length and measured soil saccharides in a seasonally dry California grassland soil; we evaluated total sugars as well as the mix of sugars present in the soil. Soil cores were collected monthly from July 2014 to February 2015. Sugar residues were analyzed using Gas Chromatography—Mass Spectroscopy (GC-MS). Drier soils showed larger pools of sugar residues; these residues decreased as moisture increased across sample dates and treatments. Plant removal only slightly reduced soil saccharide levels. However, the pools of individual saccharides varied only modestly across all treatments and dates, and correlated with total microbial biomass, suggesting that extracellular polysaccharides may be a constitutive response to survival in soil, rather than an inducible response to dry conditions.

18766. 题目: Influence of soil properties and feedstocks on biochar potential for carbon mineralization and improvement of infertile soils
文章编号: N18071110
期刊: Geoderma
作者: Ali El-Naggar, Sang Soo Lee, Yasser Mahmoud Awad, Xiao Yang, Changkook Ryu, Muhammad Rizwan, J?rg Rinklebe, Daniel C.W. Tsang, Yong Sik Ok
更新时间: 2018-07-11
摘要: The impact of biochar (BC) application on soil varies with BC feedstock and soil type. The objective of this study was to investigate the linkage between the properties and surface functionality of various BCs and their role in the rehabilitation of two infertile soils. Sandy loam (SL) and sandy (S) soils were collected from agricultural areas in Korea and Vietnam, respectively. The BCs of amur silvergrass residue (AB), paddy straw (PB), and umbrella tree (UB) were applied to the soils at a rate of 30 t ha-1 and incubated at 25 °C for 90 d. Soil carbon (C) mineralization was investigated by a periodic measurement of CO2 efflux. Soil texture strongly influenced the CO2 efflux more than the BC type as indicated by 2–4 folds increase in cumulative CO2-C efflux from the SL soil compared to that from the S soil. For the PB-, AB-, and UB-treated S soils, the values of cation exchange capacity (CEC) were increased by 906%, 180%, and 130%, respectively, compared to that of the control; however, for the PB-treated SL soil, only a 13% increase in CEC was found. The pH in the PB-treated S soil sharply increased by 4.5 units compared to that in the control, due to a high concentration of readily soluble compounds in the PB and the low buffering capacity of the S soil. The S soil was more sensitive to the addition of BCs than the SL soil. A more prominent improvement in soil fertility can be achieved by BC application to the sandy soil having low clay, nutrient, and organic matter contents.

18767. 题目: Effects of hydraulic retention time on process performance of anaerobic side-stream reactor coupled membrane bioreactors: kinetic model, sludge reduction mechanism and microbial community structures
文章编号: N18071109
期刊: Bioresource Technology
作者: Lu-Man Jiang, Zhen Zhou, Tianhao Niu, Lingyan Jiang, Guang Chen, Hongjian Pang, Xiaodan Zhao, Zhan Qiu
更新时间: 2018-07-11
摘要: An anoxic/oxic membrane bioreactor (AO-MBR) and three anaerobic side-stream reactor (ASSR) coupled MBRs (ASSR-MBR) were operated to investigate the effects of hydraulic retention time of ASSR (HRTA) and to elucidate sludge reduction mechanisms in ASSR-MBRs. Increasing HRTA from 3.3 to 6.6 h improved nitrogen removal, and enhanced sludge reduction from 8.0% to 40.9% in ASSR-MBR. The sludge decay coefficient was 0.0221 d-1 in MBRs, and 0.0231-0.0345 d-1 in ASSRs. The measured lysis rate coefficient of heterotrophic biomass was 0.083-0.112 d-1 in MBRs and 0.079-0.111 d-1 in ASSRs. The hydrolysis rate coefficient of inactive particulate organic matters (POMs) in ASSRs significantly exceeded that in the MBR. At HRTA of 6.6 h, POMs hydrolysis in ASSR (38.6%) is the dominant route of sludge reduction, and cell lysis occurred principally in aerobic tanks. Illumina-MiSeq sequencing showed ASSR-MBRs enriched hydrolytic and fermentative bacteria, and confirmed that anaerobic hydrolysis contributed most to sludge reduction.

18768. 题目: Impact of lignin content on alkaline-sulfite pretreatment of Hybrid Pennisetum
文章编号: N18071108
期刊: Bioresource Technology
作者: Jingfeng Wang, Xixun Hao, Ming Yang, Yujie Qin, Lili Jia, Jie Chu, Junhua Zhang
更新时间: 2018-07-11
摘要: This work focuses to investigate the impact of lignin content on chemical compositions, crystallinity, surface characterizations, cellulase adsorption profiles and hydrolysability of Hybrid Pennisetum (HP) after alkaline sulfite pretreatment (ASP). For the HP with lower lignin content, the increase of the cellulose content by ASP was more obvious than raw HP. ASP decreased total lignin content and surface lignin content of HP substrates. HP with lower lignin content (e.g., 15%) is suitable for ASP, because a pretty perfect glucose yield (91%) was obtained using a low dosage of enzyme loadings (5 FPU of cellulases/g dry matter). The study provides a potential strategy to efficiently produce platform sugars from HP with reduced lignin content, indicating the importance of reduction HP lignin content properly by breeding or transgenesis programs. The work could also help elucidate the mechanism of alkaline sulfite pretreatment for efficient production of fermentable sugars from lignocelluloses.

18769. 题目: The effects of algal extracellular substances on algal growth, metabolism and long-term medium recycle, and inhibition alleviation through ultrasonication
文章编号: N18071107
期刊: Bioresource Technology
作者: Ze Yu, Haiyan Pei, Qingjie Hou, Changliang Nie, Lijie Zhang, Zhigang Yang, Xiaodong Wang
更新时间: 2018-07-11
摘要: The algal extracellular substances (AESs), mainly excreted in the lag and stationary phases, inhibited the algal growth and culture recycle. The AESs consisted of protein-like substances and saccharides, which restrained the algal lipid and protein biosynthesis. Moreover, the increasing reactive oxygen species and anti-oxidative enzymes caused by AESs led to the oxidative damage and suppressed the cell activity. The AESs affected the cells through two possible ways: one is the AESs adhered to the cell surfaces; another is the cells yielded signal molecules in response to the AESs. Fortunately, the ultrasound degraded the AESs into small molecules, which clearly alleviated the limitation and recovered the algal biomass and metabolism to recover. This study demonstrated that ultrasonication is a promising way to alleviate the AESs, which facilitating the medium recycle for long-term continuous microalgae production.

18770. 题目: Land Use Controls on the Spatial Variability of Dissolved Black Carbon in a Subtropical Watershed
文章编号: N18071106
期刊: Environmental Science & Technology
作者: J. Alan Roebuck, Jr., Michael Seidel, Thorsten Dittmar, Rudolf Jaffé
更新时间: 2018-07-11
摘要: Rivers export roughly 250 Pg of dissolved organic carbon (DOC) to coastal oceans. DOC exported from rivers can be a reflection of watershed dynamics, and changes in land use can lead to shifts in the molecular composition and reactivity of riverine DOC. About 10% of DOC exported from rivers is dissolved black carbon (DBC), a collection of polycondensed aromatic compounds derived from the incomplete combustion of biomass and fossil fuels. While DOC and DBC export are generally coupled, the effects of watershed land use on DBC quality are not well understood. In this study, DBC samples were collected throughout the Altamaha River watershed in Georgia, USA. DBC was characterized using the benzenepoly(carboxylic acid) method and Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). DBC had a more polycondensed character in areas of the watershed with less anthropogenic disturbance. Furthermore, FTICR-MS revealed that DBC became enriched with a lower molecular weight, heteroatomic signature in response to higher anthropogenic activity. As global land cover continues to change, this study demonstrates on a localized scale that watershed land use can influence the export and composition of DBC, which may have further implications for global carbon and nutrient cycling.

18771. 题目: Mechanical pretreatment for increased biogas production from lignocellulosic biomass; predicting the methane yield from structural plant components
文章编号: N18071105
期刊: Waste Management
作者: Panagiotis Tsapekos, Panagiotis G. Kougias, Irini Angelidaki
更新时间: 2018-07-11
摘要: Lignocellulosic substrates are associated with limited biodegradability due to the structural complexity. For that reason, a pretreatment step is mandatory for efficient biomass transformation which will lead to increased bioenergy output. The aim of the present study was to assess the efficiency of two pretreatment machines to enhance the methane yield of meadow grass. Specifically, the application of shearing forces with a rotated plastic sweeping brush against a steel roller significantly increased biomass biodegradability by 20% under relatively gentle operation conditions (600 rpm). The more intense operation (1200 rpm) was not associated with higher methane yield enhancement. Regarding an alternative machine, in which the brush was replaced with a coarse steel roller resulted in a more distinct effect (+27%) despite the lower rotating speed ( 400 rpm). Moreover, the association of the substrate’s individual chemical components and the practical methane yield was assessed, establishing single and multiple linear regression models. However, the estimation accuracy was rather low with either single (regressor: lignin, R2: 0.50) or multiple linear regression analyses (regressors: arabinan-lignin-protein, R2: 0.61). Results showed that poorly lignified plant tissue containing relatively high fractions of protein and arabinan is more susceptible to anaerobic digestion.

18772. 题目: Effect of humic acid & bacterial exudates on sorption–desorption interactions of 90Sr with brucite
文章编号: N18071104
期刊: Environ. Sci.: Processes Impacts
作者: Hollie Ashworth, Liam Abrahamsen-Mills, Nick Bryan, Lynn Foster, Jonathan R. Lloyd, Simon Kellet, Sarah Heath
更新时间: 2018-07-11
摘要: One of the nuclear fuel storage ponds at Sellafield (United Kingdom) is open to the air, and has contained a significant inventory of corroded magnox fuel and sludge for several decades. As a result, some fission products have also been released into solution. 90Sr is known to constitute a small mass of the radionuclides present in the pond, but due to its solubility and activity, it is at risk of challenging effluent discharge limits. The sludge is predominantly composed of brucite (Mg(OH)2), and organic molecules are known to be present in the pond liquor with occasional algal blooms restricting visibility. Understanding the chemical interactions of these components is important to inform ongoing sludge retrievals and effluent management. Additionally, interactions of radionuclides with organics at high pH will be an important consideration for the evolution of cementitious backfilled disposal sites in the UK. Batch sorption–desorption experiments were performed with brucite, 90Sr and natural organic matter (NOM) (humic acid (HA) and Pseudanabaena catenata cyanobacterial growth supernatant) in both binary and ternary systems at high pH. Ionic strength, pH and order of addition of components were varied. 90Sr was shown not to interact strongly with the bulk brucite surface in binary systems under pH conditions relevant to the pond. HA in both binary and ternary systems demonstrated a strong affinity for the brucite surface. Ternary systems containing HA demonstrated enhanced sorption of 90Sr at pH 11.5 and vice versa, likely via formation of strontium–humate complexes regardless of the order of addition of components. The distribution coefficients show HA sorption to be reversible at all pH values studied, and it appeared to control 90Sr behaviour at pH 11.5. Ternary systems containing cyanobacterial supernatant demonstrated a difference in 90Sr behaviour when the culture had been subjected to irradiation in the first stages of its growth.

18773. 题目: Global challenges and adaptations in management practices to preserve soil carbon pool with changing climate
文章编号: N18071103
期刊: Environmental Earth Sciences
作者: Reshmi Sarkar
更新时间: 2018-07-11
摘要: Increasing CO2 levels and its consequent effects have been prominent with climate change. Three out of ten transgressed planetary boundaries reflect our planet’s status at tipping point. Soil Organic Carbon (SOC) which helps soil supply water and nutrients to plants through roots is inherently related to various ecological systems and needs urgent attention. Although the total SOC globally is more than the total carbon in biosphere and atmosphere, the vulnerability of SOC due to anthropogenic activities is unavoidable. The environmental factors affecting sequestration of SOC, soil fertility, crop production, accelerated SOC removal with rising temperatures, green-house gases emissions and climate change are interrelated. Thus, it is impossible to understand and estimate the various scenarios of impacts on SOC pool with ever-changing ecosystems and related processes in soil environment completely. Based on currently predicted climate change scenarios, if deforestation is controlled and reestablishment is achieved, tropical forests can trap atmospheric CO2 in the cheapest way and function as the largest sink on earth. The agricultural management practices (AMPs), which have been practiced in the last two decades and found helpful are suitable. However, some innovative adaptations such as crop modelling, selecting types of residue to change microbial communities, practices of grassland-grazing and low-C-emission AMPs are also necessary. To achieve the millennium development goals, we must accomplish food security, which relates all 17 sustainable development goals (SDGs) also relays agricultural systems, soil systems, ecosystem services, soil fertility and how best we nurture SOC pool with supportive AMPs.

18774. 题目: Bio-cord plays a similar role as submerged macrophytes in harboring bacterial assemblages in an eco-ditch
文章编号: N18071102
期刊: Environmental Science and Pollution Research
作者: Lei Zhou, Chengrong Bai, Jian Cai, Yang Hu, Keqiang Shao, Guang Gao, Erik Jeppesen, Xiangming Tang
更新时间: 2018-07-11
摘要: Artificial carriers are widely used to enhance the formation of biofilm and improve pollutants’ removal efficiency in agricultural wastewater treatment ditches (eco-ditches), yet comprehensive insight into their bacterial community is scarce. In this study, bacterial diversities in four different habitats—the water column, surface sediments, submerged macrophytes (Myriophyllum verticillatum L.), and the artificial carriers (bio-cord)—were compared in a Chinese eco-ditch. Comparable richness and evenness of bacterial communities were observed on M. verticillatum and bio-cord, both being higher than for free-living bacteria in the water column but lower than for bacteria in the surface sediment. The highest similarity of bacterial community composition and structure also occurred between M. verticillatum and the bio-cord, dominated by α- and γ-proteobacteria, Verrucomicrobia, and Bacteroidetes. Firmicutes and Planctomycetes, respectively, were the exclusive abundant phyla in M. verticillatum and the bio-cord, probably indicating the unique interaction between M. verticillatum and their epiphytic bacteria. Some abundant genera, such as Roseomonas, Pseudomonas, and Rhodopirellula, which were exclusively observed in M. verticillatum or the bio-cord, have been reported to have the same capacity to remove nitrogen and organic matter in wastewater treatment systems. In conclusion, in the studied eco-ditch, the bio-cord was found to play a similar role as submerged macrophytes in harboring bacterial assemblages, and we therefore propose that bio-cord may be a good alternative or supplement to enhance wastewater treatment in agricultural ditches.

18775. 题目: Production, characterization, and potential of activated biochar as adsorbent for phenolic compounds from leachates in a lumber industry site
文章编号: N18071101
期刊: Environmental Science and Pollution Research
作者: Flavia Lega Braghiroli, Hassine Bouafif, Nesrine Hamza, Carmen Mihaela Neculita, Ahmed Koubaa
更新时间: 2018-07-11
摘要: There is growing interest in low-cost, efficient materials for the removal of organic contaminants in municipal and industrial effluents. In this study, the efficiency of biochar and activated biochar, as promising adsorbents for phenol removal, was investigated at high (up to 1500 mg L-1) and low concentrations (0.54 mg L-1) in synthetic and real effluents (from wood-residue deposits in Québec), respectively. The performance of both materials was then evaluated in batch adsorption experiments, which were conducted using a low solid/liquid ratio (0.1 g:100 mL) at different phenol concentrations (C0 = 5–1500 mg L-1), and at 20 °C. Activated biochars presented higher phenol adsorption capacity compared to biochars due to their improved textural properties, higher micropore volume, and proportion of oxygenated carbonyl groups connected to their surface. The sorption equilibrium was reached within less than 4 h for all of materials, while the Langmuir model best described their sorption process. The maximum sorption capacity of activated biochars for phenol was found to be twofold relative to biochars (303 vs. 159 mg g-1). Results also showed that activated biochars were more effective than biochars in removing low phenol concentrations in real effluents. In addition, 95% of phenol removal was attained within 96 h (although 85% was removed after 4 h), thus reaching below the maximum authorized concentration allowed by Québec’s discharge criteria (0.05 mg L-1). These results show that activated biochars made from wood residues are promising potential adsorbent materials for the efficient treatment of phenol in synthetic and real effluents.

18776. 题目: Effects of pipe material on nitrogen transformation, microbial communities and functional genes in raw water transportation
文章编号: N18071018
期刊: Water Research
作者: Hang Xu, Chenshuo Lin, Wei Chen, Zhen Shen, Zhigang Liu, Taoyuan Chen, Yueting Wang, Yang Li, Chunhui Lu, Jian Luo
更新时间: 2018-07-10
摘要: Raw water transportation pipelines are vital in an urban water supply system for transporting raw water to drinking water treatment plants. This study investigated the effects of pipe material on nitrogen transformation, microbial communities and characteristics of related function genes in paint-lined steel pipe (PLSP) and cement-lined steel pipe (CLSP) raw water model systems. We established quantitative relationships between specific functional genes and change rates of nitrogen pollutants, which were verified by field investigation on nitrogen pollutant transformations in real raw water transportation systems. The results showed that the CLSP produced higher ammonia nitrogen (NH4+-N) transformation rates and higher effluent concentrations of nitrate nitrogen (NO3- -N) and dissolved organic nitrogen (DON) than the PLSP. Both pipes achieved high and stable nitrite nitrogen (NO2- -N) and low total nitrogen (TN) removal efficiency. Nitrification was found to be the dominant process in both model systems, especially in the CLSP. Characteristics of microbial communities and nitrogen functional genes, which were analysed by high-throughput pyrosequencing and quantitative polymerase chain reaction (qPCR), respectively, varied between the two pipe systems. Nitrogen transformation pathways, identified by path analysis, were also different between the PLSP and CLSP due to different microbial community characteristics and synergistic effects of nitrogen functional genes. In the CLSP, (NH4+-N→NO2 -N) with part denitrification, was the primary transformation pathway of ammonia nitrogen (NH4+-N), while only ammonia oxidization contributed to NH4+-N transformation in the PLSP. (NO2- -N→NO3- -N) was the main pathway involved in NO2- -N transformation and NO3 -N accumulation. The TN removal showed complex relationships with nitrification, denitrification and nitrogen fixation processes. These findings provided molecular-level insights into nitrogen pollutant transformations during the transportation of raw water through different types of pipes and technical support for the selection of raw water pipe materials. In our study area, the Taihu basin, China, PLSP was better than CLSP for distributing raw water in a short transportation distance, due to the lower effluent concentrations of DON and NO3- -N and less abundance of microorganisms.

18777. 题目: Formation of brominated trihalomethanes during chlorination or ozonation of natural organic matter extracts and model compounds in saline water
文章编号: N18071017
期刊: Water Research
作者: Zheng-Qian Liu, Amisha D. Shah, Elisabeth Salhi, Jakov Bolotin, Urs von Gunten
更新时间: 2018-07-10
摘要: Oxidation experiments (chlorine, ozone and bromine) were carried out with synthetic saline waters containing natural organic matter (NOM) extracts and model compounds to evaluate the potential of these surrogates to mimic the formation of brominated trihalomethanes (Br-THMs) in natural saline waters. Synthetic saline water with Pony Lake fulvic acid (PLFA) showed comparable results to natural brackish and sea water for Br-THMs formation during chlorination and ozonation for typical ballast water treatment conditions ([Cl2]0 ≥ 5 mg/L or [O3]0 ≥ 3 mg/L). The molar CHBr3 yield in synthetic saline waters is higher for chlorination than for ozonation, since ozone reacts slower with bromide and faster with THM precursors. For bromination, the molar yields of CHBr3 for the NOM model compounds phenol, resorcinol, 3-oxopentanedioic acid and hydroquinone are 28, 62, 91 and 11%, respectively. CHBr3 formation is low during chlorination or ozonation of resorcinol-containing synthetic saline waters due to the faster reaction of resorcinol with these oxidants compared to the bromine formation from bromide. Oxidation experiments with mixtures of hydroquinone and phenol (or resorcinol) were conducted to mimic various functional groups of NOM reacting with Cl2 (or O3) in saline water. With increasing hydroquinone concentrations, the CHBr3 formation increases during both chlorination and ozonation of the mixtures, except for chlorination of the mixture of hydroquinone and resorcinol. The formation of THMs during chlorination of the mixture of hydroquinone and resorcinol is similar to that of resorcinol alone due to the much faster reaction of HOX with resorcinol compared to hydroquinone. In general, PLFA seems to be a reasonable DOM surrogate to simulate CHBr3 formation for realistic ballast water treatment. During chlorination, CHBr3 formations from phenol- and PLFA-containing synthetic brackish waters are comparable, for similar phenol contents.

18778. 题目: Simultaneous removal of dissolved organic matter and nitrate from sewage treatment plant effluents using photocatalytic membranes
文章编号: N18071016
期刊: Water Research
作者: Hang Xu, Yang Li, Mingmei Ding, Wei Chen, Kang Wang, Chunhui Lu
更新时间: 2018-07-10
摘要: The residual dissolved organic matter (DOM) and nitrate in sewage treatment plant (STP) effluent have potential negative impacts on the aqueous environment. To that end, we used formic acid (FA) to enhance the photochemical behavior of the photocatalytic membrane for the simultaneous removal of DOM and nitrate from secondary STP effluent. Effluent samples were collected from two different biological treatment processes, Anaerobic-Oxic and Anaerobic-Anoxic-Oxic-membrane bioreactor, respectively. Through Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS) analysis, we found that the addition of FA resulted in a similar molecular transformation in different STP effluent samples. Besides, the radical signal of the carboxyl anion could be observed during the photocatalytic process. Based on the results, we proposed the mechanism of the process that carboxyl anion radicals generated by FA could attack DOM and result in further oxidation of the DOM transition state to CO2 or small molecule by nitrate. Meanwhile, CHON and CHOS compounds in DOM were attacked by the carboxyl anion radicals more easily than CHO compounds. Moreover, long-term use of the membrane confirmed its durability and reusability in practical applications. At a moderate FA concentration and lower hydraulic retention time, the nitrate and DOM removal efficiencies for the sample from JX STP were 68% and 70%, respectively, whereas those of the CD STP sample were 85% and 60%. The removal of DOM and nitrate from different STP effluents using photocatalytic membranes is an advanced approach for the treatment of secondary effluent, and may be applicable to other membranes or systems.

18779. 题目: Intermolecular interactions of polysaccharides in membrane fouling during microfiltration
文章编号: N18071015
期刊: Water Research
作者: Shujuan Meng, Wenhong Fan, Xiaomin Li, Yu Liu, Dawei Liang, Xiaoxing Liu
更新时间: 2018-07-10
摘要: Membrane technology has been widely employed for seawater desalination, water and wastewater reclamation, while membrane fouling still remains as a major challenge. The polysaccharides in extracellular polymeric substances (EPS) have been recognized as an important foulant that causes serious membrane fouling, while the detailed structure of polysaccharides and the intermolecular interactions between them have not been adequately disclosed. In this study, two different polysaccharides and their mixtures were used to study the intermolecular cross-linking of polysaccharides as well as its effects on membrane fouling. Results demonstrated that the fouling propensities of distinct polysaccharides were completely different, which was attributed to the different intermolecular interactions lying in polysaccharides. The cross-linking among molecules of polysaccharide, regardless of the homogeneity, was found to form complex networks and determine the effective dimension of polysaccharides. Depending on the effective dimension of foulants, pore blocking and cake layer occurred subsequently during filtration processes. In light of this, it potentially gives new insights into the fouling behaviours by combining the structure-function knowledge of polysaccharides with their fouling propensity. In addition, transparent exopolymeric particles (TEP) measurement was found to provide an intuitionistic evaluation of the complex networks formed from polysaccharides, so that may act as a good indicator of fouling during membrane filtration.

18780. 题目: Spatial and temporal shifts in fluvial sedimentary organic matter composition from a High Arctic watershed impacted by localized slope disturbances
文章编号: N18071014
期刊: Organic Geochemistry
作者: David M. Grewer, Melissa J. Lafrenière, Scott F. Lamoureux, Myrna J. Simpson
更新时间: 2018-07-10
摘要: Arctic warming may induce slope failure in upland permafrost soils. These landslide-like events, referred to as active layer detachments (ALDs), redistribute soil material into hydrological networks during spring melt and heavy rainfall. In 2011, 2013 and 2014, fluvial sediments from the West River at the Cape Bounty Arctic Watershed Observatory were sampled where ALDs occurred in 2007–2008. Two ALD-impacted subcatchments were examined exhibiting either continuing disturbance or short-term stabilization. Solid-state 13C nuclear magnetic resonance (NMR) spectroscopy and targeted biomarker analysis via gas chromatography–mass spectrometry were used to investigate shifts in organic matter (OM) composition. Additionally, radiocarbon ages were determined using accelerator mass spectrometry. Biomarker concentrations and O-alkyl carbon assessed via NMR were both lower in sediments nearest the active disturbance and increased in sediments downstream where other aquatic inputs became more dominant. This suggests immobilization of recalcitrant OM near the ALD and the sustained transport of labile ALD-derived OM further downstream. Shifts toward older radiocarbon dates along the river between 2011 and 2014 suggest the continued transport of permafrost-derived OM downstream. The stabilizing subcatchment revealed high O-alkyl carbon via NMR and increased concentrations of unaltered terrestrial-derived biomarkers indicative of enhanced OM accumulation following ALD activity. The relatively young radiocarbon ages from these sediments suggest accumulation from contemporary sources and potential burial of the previously dispersed ALD inputs. Within the broader context of Arctic climate change, these results portray a complex environmental trajectory for thaw-released permafrost-derived OM and highlight uncertainty in the relationship between lability and persistence upon release by permafrost disturbance.