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8101. 题目: Application of sewage sludge to agricultural soil increases the abundance of antibiotic resistance genes without altering the composition of prokaryotic communities
文章编号: N18081110
期刊: Science of The Total Environment
作者: Julen Urra, Itziar Alkorta, Iker Mijangos, Lur Epelde, Carlos Garbisu
更新时间: 2018-08-11
摘要: The application of sewage sludge as soil amendment is a common agricultural practice. However, wastewater treatment plants, sewage sludge and sewage sludge-amended soils have been reported as hotspots for the appearance and dissemination of antibiotic resistance, driven, among other factors, by selection pressure exerted by co-exposure to antibiotics and heavy metals. To address this threat to environmental and human health, soil samples from a long-term (24 years) field experiment, carried out to study the impact of thermally dried and anaerobically digested sewage sludge (at different doses and frequencies of application) on agricultural soil quality, were investigated for the presence of genes encoding antibiotic resistance (ARGs) and mobile genetic elements (MGEs). Sewage sludge-induced changes in specific soil physicochemical and microbial properties, as indicators of soil quality, were also investigated. The application of sewage sludge increased the total concentration of copper and zinc in amended soils, but without affecting the bioavailability of these metals, possibly due to the high values of soil pH and organic matter content. Soil microbal quality, as reflected by the value of the Soil Quality Index, was higher in sewage sludge-amended soils. Similarly, the application of sewage sludge increased soil microbial activity and biomass, as well as the abundance of ARGs and MGE genes, posing a risk of dissemination of antibiotic resistance. In contrast, the composition of soil prokaryotic communities was not significantly altered by the application of sewage sludge. We found correlation between soil Cu and Zn concentrations and the abundance of ARGs and MGE genes. It was concluded that sewage sludge-derived amendments must be properly treated and managed if they are to be applied to agricultural soil.
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8102. 题目: Fertilizer regime changes the competitive uptake of organic nitrogen by wheat and soil microorganisms: An in-situ uptake test using 13C, 15N labelling, and 13C-PLFA analysis
文章编号: N18081109
期刊: Soil Biology and Biochemistry
作者: Qingxu Ma, Lianghuan Wu, Juan Wang, Jinzhao Ma, Ningguo Zheng, Paul W. Hill, David R. Chadwick, Davey L. Jones
更新时间: 2018-08-11
摘要: Fertilizer regime affects plant growth and soil microbial community composition, however, its impact on organic nitrogen (N) uptake by plants remains poorly understood. To address this, we undertook an in-situ, short-term uptake experiment based on 13C, 15N labelling, and 13C-PLFA analysis at two long-term (6 year) fertilizer trial sites (Jintan and Changshu). Each site had five treatments: a control without fertilizers, NPK fertilizers, 50% NPK fertilizer +6 t/ha pig manure, 100% NPK fertilizer + cereal straw, and 50% NPK fertilizer +6 t/ha pig manure and cereal straw. Overall, we found that 6–21% and 6–11% of the added 13C-15N-glycine was taken up intact by wheat, while 18–35% and 8–20% was captured by soil microorganisms in Jintan and Changshu locations, respectively. These results indicate that wheat has an appreciable capacity to utilize organic N, even in fertile agricultural soils. Organic N uptake by wheat correlated positively with ammonium and nitrate soil contents, indicating that inorganic N may enhance organic N capture by increasing plant biomass. The 13C:15N ratio in the microbial biomass showed that 32–71% and 13–71% of the 15N was absorbed through a direct uptake route in Jintan and Changshu soils. Chemical fertilizer reduced microbial biomass and increased the proportion of intact glycine uptake by wheat. Gram-positive bacteria accounted for 18–23%, and 13–15% of the total 13C labelled PLFA in Jintan and Changshu, respectively, while Gram-negative bacteria accounted for 43–48% and 66–72% indicating that they are the dominant competitors with plants for soil nutrients. Total 15N uptake by wheat and microorganisms was highest in the 50% NPK fertilizer + pig manure and cereal straw treatment at both sites, indicating that it represents the best fertilizer practice for sustainable food production, as it not only reduced chemical fertilizer application, improved wheat growth and microbial biomass, but also increased wheat utilization of soil organic N.
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8103. 题目: Interaction between humic acid and protein in membrane fouling process: A spectroscopic insight
文章编号: N18081108
期刊: Water Research
作者: Yan-Fang Guan, Chen Qian, Wei Chen, Bao-Cheng Huang, Yun-Jie Wang, Han-Qing Yu
更新时间: 2018-08-11
摘要: Membrane fouling remains a major challenge for applying membrane technology to water treatment and, therefore, new tools to recognize the key foulants are essential for characterizing and evaluating the membrane fouling process. In this work, fluorescence excitation emission matrix coupled with parallel factor framework-clustering analysis was used to investigate the membrane fouling during the filtration process of humic acid (HA) and bovine serum albumin (BSA) solution by polyvinylidene fluoride membrane. Interestingly, the interaction between BSA and HA in the membrane fouling process was observed, and was further confirmed by infrared microspectroscopy and two-dimensional correlation spectroscopic analysis. In addition, the HA-induced membrane fouling was observed to be initially relieved, but became aggravated when a certain amount of BSA was added. Furthermore, with such an integrated approach, the OH groups in HA and amide bands in BSA were found to be mainly responsible for the membrane fouling and the HA-BSA interaction was mainly caused by the encapsulation of BSA with HA. This work develops a new method for probing membrane fouling and demonstrates the interaction between membrane foulants and its roles in membrane fouling process. Furthermore, the integrated approach developed in this work has a potential to explore other types of interfacial interactions.
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8104. 题目: Effect of sulfate radicals-based oxidation pretreatments for mitigating ceramic UF membrane fouling caused by algal extracellular organic matter
文章编号: N18081107
期刊: Water Research
作者: Xiaoxiang Cheng, Daoji Wu, Heng Liang, Xuewu Zhu, Xiaobin Tang, Zhendong Gan, Jiajian Xing, Xinsheng Luo, Guibai Li
更新时间: 2018-08-11
摘要: Algal extracellular organic matter (EOM) released from Microcystis aeruginosa can cause severe membrane fouling during algae-laden water treatment. To solve this problem, three typical sulfate radicals-based advanced oxidation processes (SR-AOPs), i.e., ferrous iron/peroxymonosulfate (Fe(II)/PMS), UV/PMS and UV/Fe(II)/PMS, were employed as membrane pretreatment strategies. Their performance on mitigating EOM fouling of a ceramic UF membrane was systematically investigated and compared in the present study. The results indicated that SR-AOPs pretreatments could promote the reduction of DOC and UV254, and the removal performance showed an apparent regularity of UV/Fe(II)/PMS > Fe(II)/PMS > UV/PMS. The pretreatments were very effective for decomposing high-MW biopolymers (>20,000 Da) into low-MW humic substances (1000–20,000 Da), thus reducing the accumulation of high-MW biopolymers on membrane surface. With respect to membrane fouling control, Fe(II)/PMS significantly mitigated both reversible and irreversible membrane fouling, whereas UV/PMS only reduced reversible fouling, and exhibited little effect on irreversible fouling. By contrast, UV/Fe(II)/PMS showed the best performance for fouling reduction due to the synergistic effect of UV and Fe(II) for PMS activation. The dominating fouling mechanism was governed by both pore blockage and cake filtration, likely due to the bimodal MW distribution of EOM, and SR-AOPs pretreatments delayed the transition from pore blockage to cake filtration. In addition, SR-AOPs prior to UF membrane were also very effective to improve the removal of micropollutants (i.e., ATZ, SMT and p-CNB). These results demonstrate the potential application of SR-AOPs as pretreatment for membrane fouling control during algae-laden water treatment.
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8105. 题目: A comparison of equilibrium and kinetic passive sampling for the monitoring of aquatic organic contaminants in German rivers
文章编号: N18081106
期刊: Water Research
作者: Yoonah Jeong, Andreas Schäffer, Kilian Smith
更新时间: 2018-08-11
摘要: The performances of an equilibrium and a kinetic passive sampler for monitoring a range of organic contaminants (Log KOW from −0.03 to 6.26) were evaluated in the effluent of a wastewater treatment plant, the receiving Saar river as well as the Mosel river in Germany. The polar organic chemical integrative sampler (POCIS) and a new mixed polymer sampler (MPS) were selected as kinetic and equilibrium passive samplers, respectively. Concentrations were described in terms of a time-weighted average concentration (CTWA) from the POCIS measurements and as an equilibrium concentration from the MPS (CEquil-MPS) and POCIS membrane (CEquil-PES) analyses. Twenty-seven compounds could be detected, including eight priority substances of the EU Water Framework Directive. Both sampler types detected a similar range of compounds in the low ng/L to μg/L range, with a high proportion of pharmaceuticals being detected at all sampling sites. To account for uncertainty in the POCIS sampling rates, a range in CTWA was estimated by adopting low and high sampling rates. For the compounds that were detected in the POCIS this range was within a factor of 3.5. Interestingly, the MPS extracts showed lower ionisation artefacts than the POCIS extracts during the LC-MS/MS analysis. Finally, total water concentrations (CTotal) were estimated from the dissolved concentrations, literature organic carbon partition coefficients (KOC) and the total organic carbon levels measured in the rivers. For the compounds in this study, negligible differences between CTotal and the passive sampler-derived dissolved concentrations were found with a maximum difference of 15% for diclofenac. Overall, this study demonstrated that the parallel application of kinetic and equilibrium passive samplers can improve the description of the water quality.
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8106. 题目: A novel combined process for efficient removal of Se(VI) from sulfate-rich water: Sulfite/UV/Fe(III) coagulation
文章编号: N18081105
期刊: Chemosphere
作者: Xing Wang, Hui Liu, Chao Shan, Weiming Zhang, Bingcai Pan
更新时间: 2018-08-11
摘要: The efficient removal of Se(VI) from sulfate-rich water is challenging as most reported processes last for hours to days. In this study, a combined sulfite/UV/Fe(III) coagulation process was proposed for efficient Se(VI) removal from sulfate-rich water within a short time (∼1 h). In the presence of sulfate (1000 mg L−1), over 99% of Se(VI) (initially at 10 mg L−1) could be reduced by sulfite (5.0 mM) with a UV dose of 16 J cm−2 (within 20 min) into Se(IV) as the sole observed product. An alkaline pH (>9) was required for the reduction process, which was naturally obtained with the addition of sulfite. Scavenging experiments with N2O and NO3 both indicated that hydrated electrons (eaq) were responsible for Se(VI) reduction by sulfite/UV. The presence of chloride, sulfate, phosphate, and carbonate (up to 10 mM) showed negligible influence on Se(VI) reduction, whereas nitrate and humic acid inhibited Se(VI) reduction to different extents depending on their concentrations. By Fe(III) coagulation, Se(IV) in the co-presence of sulfite and sulfate was efficiently removed at an OH/Fe molar ratio of 1.8–2.8. The removal of Se(IV) by Fe(III) coagulation responded insignificantly to chloride, nitrate, or sulfate (up to 10 mM), whereas it was adversely affected at high levels of carbonate (10 mM) and phosphate (1 mM). The combined sulfite/UV/Fe(III) coagulation process was validated for the efficient removal of Se(VI) from synthetic sulfate-rich solution, simulated wastewater, and authentic smelting wastewater (in 1.1 h). The introduced sulfite underwent minor consumption during UV irradiation and was almost (∼90%) removed after coagulation.
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8107. 题目: In vitro inhalation bioaccessibility for particle-bound hydrophobic organic chemicals: Method development, effects of particle size and hydrophobicity, and risk assessment
文章编号: N18081104
期刊: Environment International
作者: Shan-Yi Xie, Jia-Yong Lao, Chen-Chou Wu, Lian-Jun Bao, Eddy Y. Zeng
更新时间: 2018-08-11
摘要: Bioaccessibility of particle-bound hydrophobic organic contaminants and related particle size effects are significant for assessing the potential human health risk via inhalation exposure, but have not been clearly evaluated. To fill this knowledge gap, the present study developed an in vitro method to estimate the inhalation bioaccessibility of particulate polycyclic aromatic hydrocarbons (PAHs) using simulated human lung fluids, i.e., a modified Gamble's solution (MGS) and artificial lysosomal fluid (ALF) with Tenax as the absorption media. Assay parameters, namely incubation time (10 d) and influence of filter use, were optimized for establishing the in vitro method. The results showed that the bioaccessibility of PAHs increased with increasing particle size, but other factors, such as total organic carbon and chemical hydrophobicity, also played a large role in the fate of these compounds. The results from this portion of the present study were then used to evaluate human health risk, which showed that the risk of these particle-bound PAHs by incorporating size-dependent PAHs bioaccessibility and deposition efficiency in the human respiratory tract into inhalation exposure risk calculations was reduced by >90% when compared to using total concentration. This suggested that the inhalation bioaccessibility and deposition efficiency of hydrophobic organic chemicals should be included in human health risk assessment.
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8108. 题目: Zn-Sr isotope records of the Ediacaran Doushantuo Formation in South China: diagenesis assessment and implications
文章编号: N18081103
期刊: Geochimica et Cosmochimica Acta
作者: Yiwen Lv, Sheng-Ao Liu, Huaichun Wu, Simon V. Hohl, Shouming Chen, Shuguang Li
更新时间: 2018-08-11
摘要: Recent studies show that zinc isotopes could provide valuable clues to environmental change and biogeochemical cycle of the past oceans. This study reports a modified procedure for leaching the carbonate fractions in sedimentary rocks, a thorough evaluation of diagenetic effects, and systematic variations of Zn and Sr isotope ratios in lower part of the Ediacaran stratigraphic unit deposited in the aftermath of the Marinoan glaciation in South China. The influence of post-depositional diagenesis on Zn isotope compositions of the studied samples is assessed by comparing δ66Zn to other geochemical indexes (87Sr/86Sr, δ13C, δ18O and Mn/Sr ratios). In the five studied cap carbonate sections (Member I of the Doushantuo Formation), dolostones from four sections have δ66Zn values positively correlated with δ18O values and negatively correlated with 87Sr/86Sr ratios (0.7081 to 0.7204). These correlations suggest that these cap dolostone samples have been modified by post-depositional diagenesis. The light δ66Zn value (-0.02‰) suggests that initial Zn isotope ratios of cap dolostones could have been reset by hydrothermal fluids with relatively high Zn concentration and low δ66Zn values.By contrast, carbonates from Member II of the Doushantuo Formation above cap dolostones are relatively pristine based on their low 87Sr/86Sr ratios (0.7079 to 0.7086) being indistinct from the proposed early Ediacaran seawater 87Sr/86Sr values. Chemical and isotopic variations in these samples are interpreted to reflect primary signals that record paleo-environmental changes of the early Ediacaran ocean. A rapid increase of δ66Zn from ∼0.3‰ to 1.1‰ occurs in the middle part of Member II, accompanying by relatively invariant 87Sr/86Sr ratios that imply insignificant changes in input from continental weathering. Considering the limited change in atmospheric oxygen during this period, the rapid δ66Zn raise indicates an increase in buried organic matters, which is consistent with the coupled positive shift of δ13Ccarb, as well as the fossil records found in the same strata. These results provide insights into Zn cycling in the post-Marinoan oceans and facilitate the application of Zn isotopes in carbonates as a proxy for the fate of marine organic matter.

8109. 题目: Methane fluxes in marine sediments quantified through core analyses and seismo-acoustic mapping (Bornholm Basin, Baltic Sea)
文章编号: N18081102
期刊: Geochimica et Cosmochimica Acta
作者: Karen Marie Hilligsøe, Jørn Bo Jensen, Timothy G. Ferdelman, Henrik Fossing, Laura Lapham, Hans Røy, Bo Barker Jørgensen
更新时间: 2018-08-11
摘要: Methane is a terminal product of anaerobic degradation of organic matter in subsurface marine sediments depleted of reactive oxidants. The depth and age of the sediment where sulfate is depleted determines the extent of methane production relative to the burial of organic carbon. We aimed to understand how this methane production is controlled and distributed in an apparently uniform sediment basin. We combined seismo-acoustic surveys and geochemical analyses of sediment cores to explore the distribution of methane fluxes in brackish-marine mud deposits of the Bornholm Basin, southern Baltic Sea. Geophysical mapping revealed the depth distribution of a) the thickness of the Holocene organic-rich mud layer overlaying organic-poor Postglacial clay, and b) the upper boundary of methane gas bubbles trapped in the Holocene sediment. By correlating these two parameters with the methane distributions in sediment cores from 44 stations we developed algorithms to estimate and map, at high spatial resolution, the diffusive methane fluxes in the 75-95-m deep and >4,000 km2 large Bornholm Basin. The two approaches, termed the FGD (Free Gas Depth) model and the HML (Holocene Mud Layer) model, yielded similar budgets for the total upwards methane flux through the sediment column in the Bornholm Basin, about 17 ton methane C day-1. Complete sulfate depletion at depth, and thus onset of methane production, required a minimum threshold thickness of the Holocene mud layer of 4 m. Although the Bornholm Basin has an even depth contour and uniform surface sediments, methane production was strongly focused in hotspots where the HML has greatest thickness. This heterogeneity could not be predicted from bathymetry or from properties of the surface sediment but was related to the topography of the glacial landscape buried underneath the Holocene mud blanket. This demonstrates the importance of including seismo-acoustic mapping of subsurface stratigraphy for the interpretation and geographic extrapolation of sediment core data for biogeochemical processes such as methane production and methane flux. The two approaches, which were here combined for the first time, may thereby be applied to map methane production also in other coastal and shelf sediments with shallow gas and distinct Holocene deposits.

8110. 题目: Fate and inhibitory effect of silver nanoparticles in high rate moving bed biofilm reactors
文章编号: N18081101
期刊: Science of The Total Environment
作者: Sanaz Alizadeh, Subhasis Ghoshal, Yves Comeau
更新时间: 2018-08-11
摘要: Municipal water resource recovery facilities are the primary recipients of a significant fraction of discharged silver nanoparticle (AgNP)-containing wastes, yet the fate and potential risks of AgNPs in attached-growth biological wastewater treatment processes are poorly understood. The fate and inhibitory effects of polyvinylpyrrolidone (PVP)-coated AgNPs at environmentally-relevant nominal concentrations (10, 100, 600 μg/L) were investigated, for the first time, in high rate moving bed biofilm reactors (MBBRs) for soluble organic matter removal. The behavior and removal of continuously added AgNPs were characterized using single-particle inductively coupled plasma mass spectrometry (spICP-MS). While no inhibitory effect at average influent concentration of 10.8 μg/L Ag was observed, soluble COD removal efficiency was significantly decreased at 131 μg/L Ag in 18 days and 631 μg/L Ag in 5 days with suppressed biofilm viability. The inhibitory effect of AgNPs on treatment efficiency was highly correlated to the retained mass of total Ag in attached biofilm on the carriers. Biofilm demonstrated limited retention capacity for AgNPs over 18 days. Considerable mass of Ag (38% to 75%) was released via effluent, predominantly as NPs. We detected some chemically transformed and potentially less toxic forms of silver nanoparticles (Ag2S, AgCl), over the exposure period. This study demonstrated the distinct interaction dynamics, bioavailability and inhibitory effects of AgNPs in a biofilm system. Release of bioavailable AgNPs via effluent and AgNP-rich biofilm, sloughing off the carriers, can affect the treatment chain efficiency of downstream processes. Thus, the inhibitory effects of AgNPs can be a concern even at concentrations as low as 100 to 600 μg/L Ag in biological attached growth wastewater treatments.
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8111. 题目: Shifts in soil organic carbon dynamics under detritus input manipulations in a coniferous forest ecosystem in subtropical China
文章编号: N18081012
期刊: Soil Biology and Biochemistry
作者: Junjun Wu, Dandan Zhang, Qiong Chen, Jiao Feng, Qianxi Li, Fan Yang, Qian Zhang, Xiaoli Cheng
更新时间: 2018-08-10
摘要: The underlying mechanism of how shifts in plant detritus input impact soil organic carbon (SOC) dynamics is not fully understood. Here we investigated the soil C content in different fractions (aggregates, labile and recalcitrant pool) after two years of detritus input manipulations (i.e. detritus input and removal treatment–DIRT: control, CK; double litter, DL; no litter, NL; no roots, NR; no aboveground litter and no roots, NRNL) in a coniferous forest (Platycladus orientalis (Linn.) Franco) ecosystem in subtropical China. The root exclusion treatments (NR and NRNL) significantly decreased the macro-aggregate (>2000 μm) fraction by 23.4%–27.7% compared to CK after two-year detritus input manipulation, and accordingly decreased the C content in macroaggregates. In contrast, the aboveground litter removal and addition (DL and NL) did not significantly impact those properties. Labile SOC significantly declined in the detritus removal treatments, while recalcitrant SOC remained relatively stable. In addition, root exclusion significantly reduced total microbial biomass and most of the taxonomic biomarkers compared to the CK. Fungal biomass were positively correlated with the proportion of macroaggregates across treatments. Principal component analysis revealed the separation of root exclusion treatments from the other detritus input manipulations was based on lower soil C content and proportion of macroaggregates. Overall, our results suggest that future shifts in plant detritus input, especially decreases in belowground litter inputs, can strongly and rapidly reduce SOC pools by reducing the proportion of macroaggregates and the C content in macroaggregates, highlighting the importance of root in regulating soil C sequestration in response to future climatic scenarios.

8112. 题目: Increased chemical stability but decreased physical protection of soil organic carbon in response to nutrient amendment in a Tibetan alpine meadow
文章编号: N18081011
期刊: Soil Biology and Biochemistry
作者: Dingyu Shen, Chenglong Ye, Zhengkun Hu, Xiaoyun Chen, Hui Guo, Junyong Li, Guozhen Du, Sina Adl, Manqiang Liu
更新时间: 2018-08-10
摘要: Nutrient amendment increases plant productivity but the effects and mechanisms on soil organic carbon (SOC) accumulation and stability remain unclear, especially in nutrient deficient alpine ecosystem. Here, based on an experiment combining nitrogen (N) and phosphorus (P) input continuously for 15 years, we found that nutrient amendment did not affect total SOC content, but increased mineral-associated C with decreasing soil aggregate stability. Despite increased total phospholipid fatty acid (PLFA) and bacteria PLFA, nutrient amendment decreased soil enzyme activities involved in C cycling. The 13C NMR analyses showed that nutrient amendment decreased the aliphaticity but enhanced aromaticity of SOC. Structural equation models indicated that P availability (Olsen-P content) was most related to shifts in microbial community composition and decreased enzyme activities. Moreover, the concomitantly reduced aggregation and increased mineral-associated C were mainly attributable to the decrease of fungal biomass and increase of bacterial biomass. Together, interconnected factors such as increased acidity, aggregate destabilization, microbial community shift towards bacteria, and loss of oxidative enzyme activities could contribute to the overall response of SOC under intensive N and P input. In particular, available P rather than N may re-shape the pattern of physical and chemical stabilization of SOC, shifting from moderately physical protection to highly chemical stability, implicating the pivotal roles of P management in C cycling of alpine ecosystem.
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8113. 题目: Microbial processing of plant residues in the subsoil – The role of biopores
文章编号: N18081010
期刊: Soil Biology and Biochemistry
作者: Callum C. Banfield, Johanna Pausch, Yakov Kuzyakov, Michaela A. Dippold
更新时间: 2018-08-10
摘要: Most subsoil carbon (C) turnover occurs in biopore hotspots such as root channels and earthworm burrows. Biopores allocate large C amounts into the subsoil, where a vast capacity for long-term C sequestration is predicted. We hypothesise that organic matter (OM) cycling in biopores depends on their origin.Earthworm and root biopores were induced under field conditions and were sampled from the subsoil (45–75 and 75–105 cm) after two years of biopore formation. The effects of biopore formation on OM decomposition were studied by biomarkers: neutral sugars, cutin and suberin-derived lipids, lignin-derived phenols and free lipids. The degradation stage of OM was biopore type-specific but was only governed by the soil depth in root biopores. Degradation of OM increased from earthworm biopores to root biopores and bulk soil. Hemicelluloses (GM/AX ratio) were more strongly degraded than lignin side-chains (relative change from initial values). Two years of microbial processing during biopore formation increased the GM/AX ratio in earthworm biopores from 0.65 to 1.05 and in root biopores from 0.15 to 1.35 (both relative to source biomasses). Root biopores and bulk soil had the highest GM/AX ratios (1.2–1.3), hinting to rapid processing of plant residues and accumulation of microbial residues. The regular, frequent OM inputs by earthworms stimulated microbial growth and processing of mostly bioavailable OM and, thus, relatively enriched more persistent OM (e.g. lignin). Syringyl subunits of lignin underwent low (ratio changed from 0.35 to 0.55 relative to initial input) and vanillyl subunits underwent almost no processing in earthworm biopores indicating the preferential microbial utilisation of the easily available compounds frequently replenished by earthworm activity. After two years of decomposition of the root detritus, mainly structural plant material was enriched in root biopores. Short periods (6 months) of earthworm activity effectively recharged the highly processed OM in root biopores with fresh OM.In total, deep-rooting catch crops and short-term earthworm activities promote C accumulation in the subsoil followed by biopore-specific microbial processing predominantly governed by the C input frequency. As root biopores are up to 40 times more common than earthworm biopores, they dominate the OM input into subsoils. Such C inputs create several years lasting hotspots for preferential root growth and nutrient mobilisation in the subsoil. We conclude that root- and earthworm-derived biopores are vertical pathways for plant C from the soil surface into the subsoil and for intensive processing of litter C and sequestration of microbial necromass.

8114. 题目: Limitations on using CDOM as a proxy for DOC in temperate lakes
文章编号: N18081009
期刊: Water Research
作者: Claire G. Griffin, Jacques C. Finlay, Patrick L. Brezonik, Leif Olmanson, Raymond M. Hozalski
更新时间: 2018-08-10
摘要: Colored dissolved organic matter (CDOM) has been widely studied as part of efforts to improve understanding of the aquatic carbon cycle, by laboratory, in situ, and remote sensing methods. We studied ecoregion-scale differences in CDOM and dissolved organic carbon (DOC) to understand variability in organic matter composition and the use of CDOM as a proxy for DOC. Data from 299 lakes across the U.S. Upper Midwest showed that CDOM, measured as absorptivity at 440 nm (a440), correlated strongly with DOC (R2 = 0.81, n = 412). Colored lakes in the Northern Lakes and Forests (NLF) ecoregion drove this relationship. Lakes in the North Central Hardwood Forests (NCHF) had low color (most had a440 < 3 m−1) and weaker CDOM-DOC relationships (R2 = 0.47). Spectral slopes and specific ultraviolet absorbance (SUVA), indicated relatively low aromaticity and non-terrestrial DOM sources in low color lakes. Multiple regression analyses that included total dissolved nitrogen (TDN) and CDOM, but not chlorophyll a, improved DOC estimates in low color lakes, suggesting a dominant contribution of non-planktonic sources of low color DOM in these lakes. Our results show that CDOM is a reliable, regional proxy for DOC in lakes where forests and wetlands dominate the landscape and the DOM is primarily terrestrial in origin. Mapping of lake DOC at broad spatial scales by satellite-derived CDOM has lower accuracy in low color lakes.
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8115. 题目: Comparison of catalytically non-productive adsorption of fungal proteins to lignins and pseudo-lignin using isobaric mass tagging
文章编号: N18081008
期刊: Bioresource Technology
作者: Zhao Wang, Leif J. Jönsson
更新时间: 2018-08-10
摘要: Catalytically non-productive adsorption of fungal enzymes to pseudo-lignin (PL) was compared to adsorption to lignin preparations derived from different sources (SL, spruce; BL, birch; OL, beech) using different methods [steam pretreatment/enzymatic saccharification (SL, BL) and organosolv processing (OL)]. The protein adsorption to the SL was more extensive than the adsorption to the hardwood lignins, which was relatively similar to the adsorption to the PL. The adsorption patterns of 13 individual proteins were studied using isobaric mass tagging with TMTsixplex reagent and LC–MS/MS analysis. The results suggest that, on an average, adsorption of proteins equipped with carbohydrate-binding modules, such as the cellulases CBHI, EGII, and EGIV, was less dependent on the quality of the lignin/PL than adsorption of other proteins, such as β-Xyl, Xyn-1, and Xyn-2, which are involved in xylan degradation.

8116. 题目: A near infrared index to assess effects of soil texture and organic carbon content on soil water content
文章编号: N18081007
期刊: European Journal of Soil Science
作者: I. Soltani, Y. Fouad, D. Michot, P. Bréger, R. Dubois, C. Cudennec
更新时间: 2018-08-10
摘要: Characterization of soil hydrodynamic properties is important for assessing soil water regime. Ex situ measurements are costly and time consuming. Reflectance spectroscopy can rapidly estimate of several soil properties including soil water content (SWC). Here, we evaluated the ability of visible (vis) and near‐infrared (NIR) spectroscopy to assess the effects of soil texture and soil organic carbon (SOC) content on SWC. Thirteen undisturbed soil surface blocks were sampled in 2014 across the Brittany region, western France. Textural classes ranged from sandy loam to sandy clay loam texture, and SOC content ranged from 8.12 g kg‐1 to 62.3 g kg‐1. Aggregates of 3–4‐cm width and 5–6‐cm height were extracted and set at 10 matric potentials from saturation to permanent wilting point (1585 kPa). At given pressure heads, soil samples were scanned in triplicate to acquire reflectance spectra between 350 and 2500 nm. Spectra were converted into continuum removal and we focused on the absorption band near 1920 nm, which is linked to combination vibrations of water. We defined a new index based on the full width at half maximum (FWHM) of the absorption feature near 1920 nm. Results showed a linear relation between this NIR index and the volumetric SWC (R2>0.9) for every soil aggregate. The slope and the intercept of the line were well correlated with soil texture and SOC content. Results indicated that the parameters of this linear relation offer a new way to study SWC and water retention properties of soils in relation to their physical properties.

8117. 题目: The influence of the conversion of grassland to cropland on changes in soil organic carbon and total nitrogen stocks in the Songnen Plain of Northeast China
文章编号: N18081006
期刊: CATENA
作者: Xiao-Dong Song, Fan Yang, Bing Ju, De-Cheng Li, Yu-Guo Zhao, Jin-Ling Yang, Gan-Lin Zhang
更新时间: 2018-08-10
摘要: The soil organic carbon (SOC) and total nitrogen (TN) of topsoil could be greatly affected by the conversion of grassland to cropland (CGC) due to vegetation harvesting and soil erosion. However, few studies have evaluated the effects of these changes in the subsoil and distinguished its main controls at the regional scale. This paper investigated the total changes in the SOC stock (SOCS) and TN stock (TNS) of soils from 0 to 30 cm and 0–100 cm in depth over the past three decades in the Songnen Plain, China, a typical Mollisol region. The CGC resulted in a moderate loss of topsoil C and N but an increase in subsoil C and N, and the soil mapping results showed that approximately 7.47 × 1011 kg C and 1.51 × 1011 kg N were accumulated during the past three decades. Prediction uncertainty was assessed by 100 model runs with random jackknife partitions, and high uncertainty was found in the areas with rapidly changing SOCS and TNS levels. Our findings indicated that subsoil should be considered in the estimation of the SOCS and TNS at the regional scale. The SOCS and TNS of the CGC areas were anticipated to increase after long-term cultivation. In view of ongoing cropland expansion, up-to-date land use and soil type data are vital for selecting monitoring sites and understanding long-term soil evolution at the regional scale.

8118. 题目: Baseline map of soil organic matter in China and its associated uncertainty
文章编号: N18081005
期刊: Geoderma
作者: Zongzheng Liang, Songchao Chen, Yuanyuan Yang, Ruiying Zhao, Zhou Shi, Raphael A. Viscarra Rossel
更新时间: 2018-08-10
摘要: Accurate digital soil maps of soil organic matter (SOM) are needed to evaluate soil fertility, to estimate stocks, and for ecological and environment modeling. We used 5982 soil profiles collected during the second national soil survey of China, along with 19 environment predictors, to derive a spatial model of SOM concentration in the topsoil (0–20 cm layer). The environmental predictors relate to the soil forming factors, climate, vegetation, relief and parent material. We developed the model using the Cubist machine-learning algorithm combined with a non-parametric bootstrap to derive estimates of model uncertainty. We optimized the Cubist model using a 10-fold cross-validation and the best model used 17 rules. The correlation coefficient between the observed and predicted values was 0.65, and the root mean squared error was 0.28 g/kg. We then applied the model over China and mapped the SOM distribution at a resolution of 90 × 90 m. Our predictions show that there is more SOM in the eastern Tibetan Plateau, northern Heilongjiang province, northeast Mongolia, and a small area of Tianshan Mountain in Xinjiang. There is less SOM in the Loess Plateau and most of the desert areas in northwest China. The average topsoil SOM content is 24.82 g/kg. The study provides a map that can be used for decision-making and contribute towards a baseline assessment for inventory and monitoring. The map could also aid the design of future soil surveys and help with the development of a SOM monitoring network in China.

8119. 题目: Phosphorus mobility in dam reservoir affected by redox oscillations: An experimental study
文章编号: N18081004
期刊: Journal of Environmental Sciences
作者: Anne Rapin, Malgorzata Grybos, Marion Rabiet, Brice Mourier, Véronique Deluchat
更新时间: 2018-08-10
摘要: The internal sedimentary phosphorus (P) load of aquatic systems is able to support eutrophication, especially in dam–reservoir systems where sedimentary P stock is high and where temporary anaerobic conditions occur. The aim of this study therefore is to examine the response of sedimentary P exposed to redox oscillations. Surface sediments collected in the Champsanglard dam–reservoir (on the Creuse River, France) were subjected to two aerobic phases (10 and 12 days) alternated with two anaerobic periods (21 and 27 days) through batch incubations. The studied sediment contained 77 ± 3 μmol/g DW of P, mainly associated with the ascorbate fraction (amorphous Fe/Mn oxyhydroxides). The used sediment was rich in organic matter (OM) (21% ± 1%) with primarily allochthone signature. Our results showed that redox oscillations enhance dissolved inorganic phosphorus release at sediment/water interface. During the first anaerobic stage, the P release was mainly controlled by the dissolution/precipitation of iron minerals. The more pronounced increase of P release during the second anaerobic stage (44%) was due to various mechanisms related to the change in quality of dissolved organic matter (DOM), namely a higher SUVA254 and humification indices. The release of more refractory DOM (rDOM) served to lower the microbial metabolism activity, possibly favored iron oxyhydroxide aggregation and thus limiting iron reduction. In addition, rDOM is able to compete for mineral P sorption sites, leading to a greater P release. In reservoir with predominant allochthone OM input, the release of more aromatic DOM therefore plays an important role in P mobility.
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8120. 题目: Clay mineralogy affects the efficiency of sewage sludge in reducing lead retention of soils
文章编号: N18081003
期刊: Journal of Environmental Sciences
作者: Giovana Clarice Poggere, Vander Freitas Melo, Beatriz Monte Serrat, Antônio Salvio Mangrich, Amanda Araújo França, Rodrigo Stuart Corrêa, Julierme Zimmer Barbosa
更新时间: 2018-08-10
摘要: Recent studies have shown the feasibility of using of sewage sludge for the remediation of heavy metal-contaminated soils. However, there are no researches to check the influence of clay mineralogy on the efficiency of the sewage sludge to remediation of contaminated soils with heavy metals. For this purpose, we use two contrasting soils: Oxisol rich in hematite and gibbsite and Inceptisol rich in kaolinite. Thermal-treated sludge was applied to Pb-contaminated soil samples and incubated for 40 days. The soil samples were submitted to seven sequential extractions: soluble-Pb, exchangeable-Pb, precipitated-Pb, organic matter-Pb, Fe and Mn oxide-Pb, gibbsite and kaolinite-Pb, and residual-Pb. The reduction of soluble Pb forms by thermal sludge application was more pronounced in the Oxisol than in the Inceptisol because of the conversion of soluble-Pb into more stable forms, such as precipitated-Pb and oxides-Pb. For Inceptisol was necessary to apply high rates of thermal sludge to reach a significant reduction in soluble-Pb contents. The addition of humic fractions in the form of thermal sludge increased the concentration of organic matter-Pb. In confined area, the use of sewage sludge to reduce the heavy metals levels in soils must be better considered, mainly in more weathered soils.
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