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31581. 题目: Estimation of soil organic carbon stocks of two cities, New York City and Paris
文章编号: N18071209
期刊: Science of The Total Environment
作者: Aurélie Cambou, Richard K. Shaw, Hermine Huot, Laure Vidal-Beaudet, Gilles Hunault, Patrice Cannavo, Fran?ois Nold, Christophe Schwartz
更新时间: 2018-07-12
摘要: In cities, the strong heterogeneity of soils, added to the lack of standardized assessment methods, serves as a barrier to the estimation of their soil organic carbon content (SOC), soil organic carbon stocks (SOCS; kgC m 2) and soil organic carbon citywide totals (SOCCT; kgC). Are urban soils, even the subsoils and sealed soils, contributing to the global stock of C To address this question, the SOCS and SOCCT of two cities, New York City (NYC) and Paris, were compared. In NYC, soil samples were collected with a pedological standardized method to 1 m depth. The bulk density (Db) was measured; SOC and SOCS were calculated for 0–30 cm and 30–100 cm depths in open (unsealed) soils and sealed soils. In Paris, the samples were collected for 0–30 cm depth in open soils and sealed soils by different sampling methods. If SOC was measured, Db had to be estimated using pedotransfer functions (PTFs) refitted from the literature on NYC data; hence, SOCS was estimated. Globally, SOCS for open soils were not significantly different between both cities (11.3 ± 11.5 kgC m 2 in NYC; 9.9 ± 3.9 kgC m 2 in Paris). Nevertheless, SOCS was lower in sealed soils (2.9 ± 2.6 kgC m 2 in NYC and 3.4 ± 1.2 kgC m 2 in Paris). The SOCCT was similar between both cities for 0–30 cm (3.8 TgC in NYC and 3.5 TgC in Paris) and was also significant for the 30–100 cm layer in NYC (5.8 TgC). A comparison with estimated SOCCT in agricultural and forest soils demonstrated that the city's open soils represent important pools of organic carbon (respectively 110.4% and 44.5% more C in NYC and Paris than in agricultural soils, for 0–30 cm depth). That was mainly observable for the 1 m depth (146.6% more C in NYC than in agricultural soils). The methodology to assess urban SOCS was also discussed.

31582. 题目: Spatial and seasonal occurrence of micropollutants in four Portuguese rivers and a case study for fluorescence excitation-emission matrices
文章编号: N18071208
期刊: Science of The Total Environment
作者: Marta O. Barbosa, Ana R. Ribeiro, Nuno Ratola, Ethan Hain, Vera Homem, M. Fernando R. Pereira, Lee Blaney, Adrián M.T. Silva
更新时间: 2018-07-12
摘要: The European Union (EU) has recommended the monitoring of specific priority substances (PSs, Directive 2013/39) and some contaminants of emerging concern (CECs, Decision 2015/495) in surface waterbodies. The present study provides spatial distributions and temporal variations of a wide range of multi-class PSs and CECs in four stressed rivers in Portugal (Ave, Le a, Antu , and Cértima). Thirteen micropollutants were found in all four rivers, including the priority pesticide isoproturon (up to 92 ng L 1), various pharmaceuticals (up to 396 ng L 1), and the UV-filter 2-ethyl-hexyl-4-methoxycinnamate (EHMC, up to 562 ng L 1) identified in Decision 2015/495. The industrial priority compound perfluorooctanesulfonic acid (PFOS) was found in three rivers (Antu , Cértima, and Le a) below the method quantification limit, together with four pharmaceuticals not included in these EU guidelines. The already banned priority pesticide atrazine was detected in Ave, Antu , and Le a (up to 41 ng L 1) and simazine in Cértima and Le a (up to 26 ng L 1). Acetamiprid and imidacloprid (included in Decision 2015/495) were only detected during the dry season in the Ave. Le a river was selected as a waterbody case study for assessment of fluorescence excitation-emission matrices (EEMs). These results matched the spatial distribution trend of micropollutants along the river, with stronger fluorescence response and higher concentrations being found downstream of industrial areas and urban wastewater treatment plants (WWTPs). Moreover, the fluorescence signature of surface water collected downstream of an urban WWTP aligned very well with that obtained for the respective WWTP effluent. Thus, actions are needed to preserve a good environmental status of these stressed European waterbodies.

31583. 题目: Different bacterial species and their extracellular polymeric substances (EPSs) significantly affected reverse osmosis (RO) membrane fouling potentials in wastewater reclamation
文章编号: N18071207
期刊: Science of The Total Environment
作者: Tong Yu, Hao Sun, Zhuo Chen, Yun-Hong Wang, Zheng-Yang Huo, Nozomu Ikuno, Kazuki Ishii, Yan Jin, Hong-Ying Hu, Yin-Hu Wu, Yun Lu
更新时间: 2018-07-12
摘要: Biofouling represents the “Achilles' heel” for reverse osmosis (RO) processes due to the growth of bacteria and their production of extracellular polymeric substances (EPSs). Although the microbial community structure on the RO membrane has been analysed previously, the bacterial species with a high potential of causing RO membrane fouling have not yet been identified clearly. The key components in EPSs causing RO membrane fouling have not been revealed either. In this study, seven different bacterial species were isolated from fouled RO membranes, and their EPSs were analysed in terms of the content of polysaccharides and proteins, fluorescence characteristics and molecular weight (MW) distributions. The membrane fouling potentials of these bacterial species and EPSs were evaluated based on normalized flux decline. Generally, under the same growth conditions, bacterial species with higher EPS concentrations, rather than higher cell numbers, resulted in more severe flux decline. The flux decline showed an apparent positive correlation with the EPS concentration, indicating that the concentration of EPS rather than the bacterial number mainly contributed to biofouling. Furthermore, it was found that the MW distribution was the key factor affecting the RO membrane fouling potential of EPSs from different bacterial species. With the increase in the percentage of the high-MW fraction (>10 kDa) in the EPSs from 12.6% to 74.4%, the normalized flux decline increased from 0.4 to 0.59. The components in EPSs with a MW over 10 kDa were also separated by the ultrafiltration membrane and were proven to have a higher membrane fouling potential.

31584. 题目: Feasting on terrestrial organic matter: dining in a dark lake changes microbial decomposition
文章编号: N18071206
期刊: Global Change Biology
作者: Amelia Fitch , Chloe Orland , David Willer , Erik J S Emilson , Andrew J Tanentzap
更新时间: 2018-07-12
摘要: Boreal lakes are major components of the global carbon cycle, partly because of sediment‐bound heterotrophic microorganisms that decompose within‐lake and terrestrially derived organic matter (t‐OM). The ability for sediment bacteria to break down and alter t‐OM may depend on environmental characteristics and community composition. However, the connection between these two potential drivers of decomposition is poorly understood. We tested how bacterial activity changed along experimental gradients in the quality and quantity of t‐OM inputs into littoral sediments of two small boreal lakes, a dark and a clear lake, and measured the abundance of operational taxonomic units and functional genes to identify mechanisms underlying bacterial responses. We found that bacterial production (BP) decreased across lakes with aromatic dissolved organic matter (DOM) in sediment pore water, but the process underlying this pattern differed between lakes. Bacteria in the dark lake invested in the energetically costly production of extracellular enzymes as aromatic DOM increased in availability in the sediments. By contrast, bacteria in the clear lake may have lacked the nutrients and/or genetic potential to degrade aromatic DOM, and instead mineralized photo‐degraded OM into CO2. The two lakes differed in community composition and the higher concentration of dissolved organic carbon in the clear lake was associated with the community assemblages in the clear lake. Furthermore, functional genes relating to t‐OM degradation were relatively higher in the dark lake. Our results suggest that future changes in t‐OM inputs to lake sediments will have different effects on carbon cycling depending on the potential for photo‐degradation of OM and composition of resident bacterial communities.

31585. 题目: Bacterial growth through microfiltration membranes and NOM characteristics in an MF-RO integrated membrane system: Lab-scale and full-scale studies
文章编号: N18071205
期刊: Water Research
作者: Ji Won Park, Young Joo Lee, Anne S. Meyer, Isabel Douterelo, Sung Kyu Maeng
更新时间: 2018-07-12
摘要: Biofilm formation on membrane surfaces causes many operational problems such as a decrease in permeate flux and an increase in hydraulic resistance. In this study, the ability of bacteria to pass through microfiltration (MF) membranes and the growth potential of microfilterable bacteria were investigated in order to understand biofouling in MF-reverse osmosis (RO) integrated membrane systems. Growth of microfilterable bacteria in MF permeate was observed, indicating that not all MF membranes can guarantee the total rejection of bacteria. Changes in natural organic matter (NOM) characteristics and growth potential of bacteria during the treatment process are important factors in the occurrence of biofilm development in water treatment systems. Analysis of protein-like and humic-like substances in NOM of two successive RO stages revealed an increase in the concentrations of both biopolymers and humic substances of RO concentrates. Unexpectedly, the use of antiscalants was seen to enhance the growth of bacteria in the RO feed water in this study. Bacterial 16s rRNA pyrosequencing revealed that passing source water through the MF membranes dramatically changed bacterial community structure. The bacterial communities that passed through the MF steps primarily belonged to the family Comamonadaceae. However, several bacteria groups including Flavobacteriaceae, Sphingobacteriaceae and Sphingomonadaceae selectively composed the biofilm community formed on the RO membranes. Thus, understanding the selectivity and filterability of MF towards microorganisms involved in biofouling on RO membrane surfaces is crucial for the improvement of membrane-related operational processes.

31586. 题目: Changes in atrazine speciation and the degradation pathway in red soil during the vermiremediation process
文章编号: N18071204
期刊: Journal of Hazardous Materials
作者: Zhong Lin, Zhen Zhen, Yanqiu Liang, Jin Li, Jiewen Yang, Laiyuan Zhong, Lirong Zhao, Yongtao Li, Chunling Luo, Lei Ren, Dayi Zhang
更新时间: 2018-07-12
摘要: Atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) is a triazine herbicide intensively used in agricultural production and is often detected in different environmental matrices at concentrations above the permitted limit. This study investigated the influence of two earthworm species (epigeic Eisenia foetida and endogeic Amynthas robustus) on atrazine speciation and the degradation pathway. Our results revealed that both earthworms significantly accelerated atrazine degradation in a 28-day vermiremediation, and the residual atrazine declined from 4.23 ± 0.21 mg/kg in bulk soils to 0.51 ± 0.29 mg/kg (E. foetida) and 0.43 ± 0.19 mg/kg (A. robustus). By consuming organic matter (from 40.37 ± 1.14 to 36.31 ± 1.55 and 34.59 ± 1.13 g/kg for E. foetida and A. robustus) and neutralizing the soil pH (from 5.37 ± 0.27 to 6.36 ± 0.11 and 6.61 ± 0.30 for E. foetida and A. robustus), both earthworms reduced humus-fixed atrazine and increased the available atrazine. The percentage of available atrazine increased from 8.80 ± 0.21% in bulk soil to 10.30 ± 0.29% and 16.42 ± 0.18% in the vermiremediation treatments. Both earthworms promoted the hydroxyatrazine pathway by consuming soil organic matter and encouraged the deethylatrazine/deisopropylatrazine pathway by neutralizing the soil pH. Our findings unravel a new mechanism of vermiremediation by improving the soil physical-chemical properties and altering the atrazine degradation pathway, providing new insights into the influential factors on atrazine bioremediation in red soil.

31587. 题目: Effect of long-term electrodialytic soil remediation on Pb removal and soil weathering
文章编号: N18071203
期刊: Journal of Hazardous Materials
作者: Gry Skibsted, Lisbeth M. Ottosen, Maria Elektorowicz, Pernille E. Jensen
更新时间: 2018-07-12
摘要: Weathering of soil minerals during long-term electrochemical soil remediation was evaluated for two different soils: an industrially Pb contaminated soil with high carbonate content and an unpolluted soil with low carbonate content. A constant current of 5 mA was applied for 842 days, and sampling was made 22 times during the treatment. The overall qualitative mineral composition was unaffected by electrodialysis, except for calcite removal which was complete. However, dissolution and removal of Al, Fe, Si, Mg, Ca and Pb from the soil during the treatment exceeded the fraction extractable by digestion in 7 M HNO3, and provided evidence of enhanced mineral dissolution induced by the current. Nevertheless, the total dissolved Si and Al only constituted 0.2–0.3% and 1.1–3.5% of the total content, while the Pb overall removal from the contaminated soil was only 8.1%. An observed reduction in the dry matter of 4.5% and 13.5% from the two soils, respectively was mainly due to dissolution of CaCO3 and organic matter, but also included a minor dissolution of other soil minerals.

31588. 题目: Priming mechanisms with additions of pyrogenic organic matter to soil
文章编号: N18071202
期刊: Geochimica et Cosmochimica Acta
作者: Silene DeCiucies, Thea Whitman, Dominic Woolf, Akio Enders, Johannes Lehmann
更新时间: 2018-07-12
摘要: Additions of pyrogenic organic matter (PyOM) to soil have been shown to both increase and decrease mineralization of native soil organic carbon (nSOC). This change in mineralization rate is referred to as priming, and may have important implications for carbon (C) turnover in soil. This study quantifies both positive and negative priming mechanisms using high-resolution carbon dioxide (CO2) measurements using a series of short-term incubation experiments with 13C-labeled PyOM added to a temperate forest soil. Moisture, nutrient availability and pH were adjusted to minimize any differential effects on nSOC mineralization. Irrespective of pyrolysis temperature (200-750°C), addition of 10 mg PyOM g-1 soil significantly decreased mineralization of nSOC. Dilution was measured against inorganic bulking materials with different surface areas and accounted for 19% of negative priming observed at day 7, and 13% at day 35. In comparison, substrate switching caused only 1% of negative priming assumed to be equivalent to PyOM mineralization itself. Inhibition did not explain reductions in nSOC mineralization since the microbial biomass did not significantly decrease (p > 0.05). Sorptive protection of dissolved organic carbon (DOC) was responsible for the majority of negative priming observed with PyOM additions based on adsorption isotherm experiments as well as co-location of nSOC on PyOM surfaces shown by nanoSIMS. Maximum sorption of soil DOC was 29 times higher to PyOM pyrolyzed at 450°C than to topsoil, and tripled with an increase in pyrolysis temperature to 750°C. This tripling in DOC sorption potential to PyOM produced at 750°C in comparison to 450°C was only reflected in a less than twice lower nSOC mineralization. Sorptive protection was with 80% the dominant negative priming mechanism on monthly timescales and likely beyond. These results have implications for long-term SOC storage, because sorption has more persistent effects than substrate switching or dilution.

31589. 题目: A liquid chromatography–mass spectrometry method for analysis of intact fatty‐acid‐based lipids extracted from soil
文章编号: N18071201
期刊: European Journal of Soil Science
作者: C. R. Warren
更新时间: 2018-07-12
摘要: Fatty‐acid‐based lipids are considered to be indicators of the structure and function of soil microbial biomass. Identifying and quantifying intact fatty‐acid‐based lipids in soil extracts is challenging because lipids range from polar (e.g. phospholipids and other membrane lipids) to non‐polar (e.g. triacylglycerols involved in energy storage). The aim of this study was to develop a liquid chromatography–mass spectrometry (LC–MS) method to identify and quantify intact fatty‐acid‐based lipids in soil extracts. Reversed‐phase LC separated fatty‐acid‐based lipids ranging from polar to non‐polar in one chromatographic analysis. Within classes, individual lipid species were separated predictably from one another on the basis of carbon numbers and degree of unsaturation, such that chromatographic retention time could be used to aid identification. Lipid species were identified based on intact mass of the lipid and by fragmentation into structure‐specific fragments that enabled compound classes and fatty acyl chains to be determined. Detection limits in positive and negative mode were better than 10 nmol l 1 for most lipid standards. In an extract of soil, 74 lipids from 10 classes were identified. The main non‐polar lipids were 12 diacylglyerol species and 16 triacylglycerol species. Polar lipids included phosphatidylcholines, phosphatidylethanolamines, monomethyl‐phosphatidylethanolamines, phosphatidylinositols and three classes of betaine lipid (diacylgycerol‐N‐trimethylhomoserine; diacylglycerylhydroxymethy‐N,N,N‐trimethyl‐β‐alanine; and diacylglycerylcarboxyhydroxymethylcholine). The LC–MS method developed provides a powerful analytical tool for analysis of fatty‐acid‐based lipids ranging from polar to non‐polar and should be useful for the culture‐ and gene‐independent assay of soil function.

31590. 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.

31591. 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.

31592. 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.

31593. 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.

31594. 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.

31595. 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.

31596. 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.

31597. 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.

31598. 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.

31599. 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.

31600. 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.