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25721. 题目: Membrane fouling in an integrated adsorption–UF system: effects of NOM and adsorbent properties
文章编号: N19120602
期刊: Environmental Science: Water Research & Technology
作者: Kai Li, Shu Li, Ce Sun, Tinglin Huang, Guibai Li, Heng Liang
更新时间: 2019-12-06
摘要: The integration of adsorption with ultrafiltration (UF) is a promising technology for the production of high quality drinking water, but it is still under debate whether the addition of an adsorbent can mitigate membrane fouling. This study was conducted to investigate the impact of properties of the adsorbent and natural organic matter (NOM) in feed water on membrane fouling in an integrated adsorption–UF system. A continuous-flow hollow fiber UF set-up with periodic backwash and aeration was used to imitate the operation of full-scale integrated adsorption–UF systems. Two types of adsorbents, commercial powdered activated carbon (PAC) and homemade mesoporous adsorbent resin (MAR), were examined. As for Songhua River water dominated by allochthonous NOM, membrane fouling of the PAC/UF system was increased by 39.5% compared with that of UF alone, whereas the addition of MAR mitigated membrane fouling by 66.4%. For the synthetic water composed of algal organic matter (AOM), membrane fouling of PAC/UF and MAR/UF systems was reduced by 40.7% and 83.3%, respectively. The results suggested that deposition of adsorbent particles and fouling resistance of the cake layer were determined by the hydrophobicity and molecular weight distribution of NOM as well as the properties of adsorbents. This study highlights the significance of adsorbent selection for the integrated adsorption–UF process according to the source and properties of NOM.
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25722. 题目: Subsoil organo-mineral associations under contrasting climate conditions
文章编号: N19120601
期刊: Geochimica et Cosmochimica Acta
作者: Thiago M. Inagaki, Angela R. Possinger, Katherine E. Grant, Steffen A. Schweizer, Carsten W. Mueller, Louis A. Derry, Johannes Lehmann, Ingrid Kögel-Knabner
更新时间: 2019-12-06
摘要: Climate differences can induce profound changes in organo-mineral associations in soils. However, the magnitude of these modifications, whether as a direct effect of climate conditions or an indirect effect through changes in soil mineralogy, are still not fully understood. In this study, we aimed to improve understanding of how climate and resultant changes in soil mineralogy affect subsoil (i.e., 0.4–0.9 m) organo-mineral interactions at the macro- and microscale. A set of subsoil samples were collected throughout an elevation gradient (approximately 1800 to 2400 mm precipitation year⁻¹ and 15 to 24°C) on Kohala Mountain, Hawaii. We carried out a combined approach of bulk soil analyses with mineral extractions and spectroscopic and spectromicroscopic analyses. Significant positive correlations (p < 0.05) between soil organic carbon (SOC) with extracted Fe and Al (dithionite citrate bicarbonate – DCB and ammonium oxalate – OX) at the bulk soil scale supported prior research showing also concurrent decline of subsoil Fe, Al and SOC above a precipitation level of ∼2000 - ∼2200 mm year^-1. However, divergence in microscale organo-mineral associations identified using NanoSIMS allowed us to disentangle the relative roles of Fe and Al in promoting organo-mineral associations. At the lower precipitation range (∼1800 mm year^-1), the clay fraction < 2 µm showed higher amounts of organic matter (OM) co-localized with Fe & Al compared with the higher precipitation level (∼2300 mm year^-1), where OM was mostly unassociated or only associated with Al. While Fe contributed to approximately 40% of the microscale organo-mineral associations in the lower precipitation site (quantified by co-localizations with OM segments), this contribution at the higher rainfall regime was only 5%. In contrast, the contribution of Al was approximately the same in both rainfall levels (approximately 30%). Therefore, associations with Al may be more important than Fe for OM stabilization under reducing climate conditions. The normalized CN:C ratio based on individual pixels was found to be higher when co-localized with Al, Fe, or both, especially under the high precipitation regime. This fact points towards the importance of Fe and Al to stabilize more N-rich OM, especially at high rainfall levels. In addition, subsoil from higher rainfall conditions exhibited more reduced forms of Fe (assessed by Fe K-edge XANES) and lower proportions of carboxyl-C (5% lower in the relative abundance) as well as higher alkyl/O-alkyl ratios determined by CP-MAS ¹³C NMR. Such differences in composition may directly influence the organo-mineral associations at both locations, as differences in Fe reduction and the presence of carboxyl-C groups are recognized to play a role in OM stabilization. We conclude that spatial relationships between Fe and Al with SOC at the microscale show a shift towards Al-dominated SOC associations at higher precipitation that could not be ascertained from bulk measurements alone. Therefore, they are of fundamental importance to understand the impact of climate change on SOC stabilization.

25723. 题目: Formation of Secondary Brown Carbon in Biomass Burning Aerosol Proxies through NO 3 Radical Reactions
文章编号: N19120511
期刊: Environmental Science & Technology
作者: Chunlin Li, Quanfu He, Anusha Priyadarshani Silva Hettiyadura, Uwe Käfer, Guy Shmul, Daphne Meidan, Ralf Zimmermann, Steven S. Brown, Christian George, Alexander Laskin, Yinon Rudich
更新时间: 2019-12-05
摘要: Atmospheric brown carbon (BrC) is an important contributor to the radiative forcing of climate by organic aerosols. Because of the molecular diversity of BrC compounds and their dynamic transformations, it is challenging to predictively understand BrC optical properties. OH radical and O3 reactions, together with photolysis, lead to diminished light absorption and lower warming effects of biomass burning BrC. The effects of night-time aging on the optical properties of BrC aerosols are less known. To address this knowledge gap, night-time NO3 radical chemistry with tar aerosols from wood pyrolysis was investigated in a flow reactor. This study shows that the optical properties of BrC change because of transformations driven by reactions with the NO3 radical that form new absorbing species and lead to significant absorption enhancement over the ultraviolet–visible (UV-vis) range. The overnight aging increases the mass absorption coefficients of the BrC by a factor of 1.3–3.2 between 380 nm and 650 nm. Nitrated organic compounds, particularly nitroaromatics, were identified as the main products that contribute to the enhanced light absorption in the secondary BrC. Night-time aging of BrC aerosols represents an important source of secondary BrC and can have a pronounced effect on atmospheric chemistry and air pollution.

25724. 题目: Comparison of ozonation and UV based oxidation as pre-treatment process for ultrafiltration in wastewater reuse: Simultaneous water risks reduction and membrane fouling mitigation
文章编号: N19120510
期刊: Chemosphere
作者: Mo Li, Qinxue Wen, Zhiqiang Chen, Yingcai Tang, Boxuan Yang
更新时间: 2019-12-05
摘要: Wastewater reuse risk and membrane fouling are two concerns in ultrafiltration (UF) of secondary effluent (SE) for wastewater reuse. In this work, several wastewater reuse risk issues, such as dissolved effluent organic matters (dEfOM), organic micro-pollutants (OMPs) and bio-toxicity of SE, as well as membrane fouling were comprehensively investigated when ozonation, UV/H₂O₂ and UV/persulfate (UV/PS) were used as the pre-treatments for UF process. To be specific, individual UF could remove DOC and UV₂₅₄ by only 7.5% and 19.8%, respectively, however, humics were largely degraded during the pre-oxidation processes revealed by molecular weight and fluorescence analysis. UF and ozonation showed limited removal of OMPs, however, UV/H₂O₂ and UV/PS dramatically degraded all the OMPs by more than 80%. Genotoxicity were not detected after the oxidation treatment. Membrane fouling may result from the collaborative effect of organic components, such as humic and protein like substances. Fourier transform infrared spectra of the fouled membranes showed that aromatic CC group and polysaccharides group in dEfOM were largely reduced after the oxidation pre-treatments, resulting in the improved membrane flux sustaining. Increased roughness of the membranes in the combined process supported that the less organics content after the oxidation pre-treatment contributed to improve the performance of the UF process. For the excellent organics degradation in UV/PS pre-treatment process, membrane fouling of subsequent UF process showed maximum mitigation.

25725. 题目: Origin and significance of saccharides during initial pedogenesis in a temperate climate region
文章编号: N19120509
期刊: Geoderma
作者: Leszek Marynowski, Oimahmad Rahmonov, Justyna Smolarek-Lach, Maciej Rybicki, Bernd R.T. Simoneit
更新时间: 2019-12-05
摘要: Saccharides are common constituents of soils, but their role and origin in the initial phases of pedogenesis remain unclear. Here we show the detailed composition of neutral sugars extracted from arenosols at different development stages, combined with additional lipids of diverse origins using gas chromatography-mass spectrometry (GC–MS). During the first stage (I) of development sucrose is the most abundant saccharide in the soil crust at up to 45,000 µg/g TOC. Sucrose is also the predominant compound in the second and third development stages, but its concentration decreased to the range of 1600 to 16,000 µg/g TOC. Stages II and III of soil development were characterized by a gradual increase in arabitol, mannitol and trehalose, compounds typical for fungi and lichen. Their abundances increased from several percent (compared to the major sucrose) to 10–32% for mannitol and 34–54% for trehalose. Moreover, in stage III there was a considerable increase in the contents of the saccharides: pinitol, myo-inositol, scyllo-inositol, arabinose, together with non-sugar compounds: dehydroabietic acid, p-hydroxybenzoic acid, gallic acid and sitosterol. All these latter compounds are higher plant markers, mainly derived from conifer detritus. The relationships between the ratios of trehalose/sucrose vs. (mannitol + arabitol)/sucrose and TOC vs. (mannitol + arabitol)/sucrose differentiated precisely the top soil layer of arenosols which are covered by different stages of biological soil crust. Our study shows that free sugars, supplemented by lipid biomarkers and total organic carbon contents, are good indicators of soil in the initial phase of pedogenesis.

25726. 题目: Effects of mixing maize straw with soil and placement depths on decomposition rates and products at two cold sites in the mollisol region of China
文章编号: N19120508
期刊: Soil and Tillage Research
作者: Ya Han, Shui-Hong Yao, Heng Jiang, Xuan-liang Ge, Yueling Zhang, Jingdong Mao, Sen Dou, Bin Zhang
更新时间: 2019-12-05
摘要: Crop straw is often retained on the ground as mulch or incorporated into soil through tillage practices. These straw management practices may affect straw decomposition rates and subsequently decomposition products due to mixing straw with soil, straw placement depths and experimental sites. Using litterbags containing maize (Zea mays. L) straw only (STO) or straw-soil mixture (SSM), this study aimed to determine the influence of mixing straw with soil and straw placement depths on decomposition rates and decomposition products, and to understand the relation of chemical composition of straw residues with straw decomposition rates. The litterbags were placed at three soil depths (0, 15 and 30 cm) in the fields at two cold sites (Hailun and Harbin), Northeast China, which had similar precipitations but different temperatures. During the 17-month experiment, the decomposition rate constants were higher by 60 %–160 % at a comparable depth in SSM than in STO. The mixing straw with soil was a more important factor in controlling straw decomposition rates than placement depths and experimental sites at the studied region. The relative abundances of O–alkyl C groups in straw residues decreased during the experimental period, even in the winter, while those of aromatic groups increased profoundly. The relative abundances of O–alkyl C groups in straw residues were lower by 0.4 %–6.9 % and those of aromatic groups were higher by 0 %–4.6 % in SSM than in STO. These findings suggest that the conventional litterbag method underestimated straw decomposition rates. Incorporating straw into soil could enhance maize straw decomposition and the formation of more stable soil organic matter (SOM) in the cold high-latitude studied region.
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25727. 题目: In-situ biodegradation of harmful pollutants in landfill by sludge modified biochar used as biocover
文章编号: N19120507
期刊: Environmental Pollution
作者: Linbo Qin, Xinming Huang, Qiang Xue, Lei Liu, Yong Wan
更新时间: 2019-12-05
摘要: MSW landfill releases a lot of harmful pollutants such as H₂S, NH₃, and VOCs. In this study, two laboratory-scale biocovers such as biochar (BC) derived from agricultural & forestry wastes (AFW) pyrolysis, and sludge modified the biochar (SBC) were designed and used to remove the harmful pollutants. In order to understand in-situ biodegradation mechanism of the harmful pollutants by the SBC, the removal performances of the harmful pollutants together with the bacterial community in the BC and SBC were investigated in simulated landfill systems for 60 days comparing with the contrast experiment of a landfill cover soil (LCS). Meanwhile, the adsorption capacities of representative harmful pollutants (hydrogen sulfide, toluene, acetone and chlorobenzene) in the LCS, BC, and SBC were also tested in a fixed bed reactor. The removal efficiencies of the harmful pollutants by the SBC ranged from 95.43% to 100.00%, which was much higher than that of the LCS. The adsorption capacities of the harmful pollutants in the SBC were 4 times higher than that of the LCS since the SBC exhibited higher BET surface and N-containing functional groups. Meanwhile, the biodegradation rates of the harmful pollutants in the SBC were also much higher than that of the LCS since the populations of the bacterial community in the SBC were more abundant due to its facilitating the growth and activity of microorganisms in the porous structure of the SBC. In addition, a synergistic combination of adsorption and biodegradation in the SBC that enhanced the reproduction rate of microorganisms by consuming the absorbed-pollutants as carbon sources, which also contributed to enhance the biodegradation rates of the harmful pollutants.
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25728. 题目: Variations in aggregate-associated organic carbon and polyester microfibers resulting from polyester microfibers addition in a clayey soil
文章编号: N19120506
期刊: Environmental Pollution
作者: G.S. Zhang, F.X. Zhang
更新时间: 2019-12-05
摘要: Organic carbon is an essential element for sustainable soil management. While the effects of microplastics on soil physical and biological properties are presenting, it remains unclear whether the organic carbon dynamics of soil are altered by increased microplastic accumulation. The objectives of this study were to evaluate the influences of different polyester microfiber (PMF 0, 0.1% and 0.3% of soil dry weight) and organic material (OM 0, 1%, 2% and 3% of soil dry weight) addition levels on soil organic carbon and to determine the PMF distribution in aggregates from a pot experiment. After 75 days of incubation under 6 wet-dry cycles, the concentrations of soil total organic carbon did not differ significantly between the PMF (9.7 ± 6.6 g kg⁻¹) and control (9.7 ± 6.9 g kg⁻¹) treatments. However, PMF addition significantly reduced the organic carbon concentration in the large (>2 mm) macro-aggregates compared to the control treatment (10.6 ± 4.8 g kg⁻¹ vs. 11.7 ± 4.4 g kg⁻¹), but the results were opposite in the small (2–0.25 mm)macro-aggregates (10.2 ± 4.9 g kg⁻¹ vs. 8.4 ± 3.8 g kg⁻¹). In this study, less than 30% of added PMFs were incorporated into soil aggregates. In addition, the abundance and average length of aggregate-associated PMF in the large (2210 ± 180 particles per g aggregate and 2.08 ± 0.17 mm) and small (1820 ± 150 particles per g aggregate and 1.68 ± 0.11 mm) macro-aggregates were significantly greater than those in the micro-aggregates (1010 ± 70 particles per g aggregate and 0.72 ± 0.05 mm). Our results demonstrate that the distribution of organic carbon in soil macro-aggregates is affected by PMFs addition. Thus, we propose that the behavior of microplastics inside soil aggregates should be further explored to clarify their effects on the physical protection of soil organic carbon.
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25729. 题目: Effect of rice straw, biochar and calcite on maize plant and Ni bio-availability in acidic Ni contaminated soil
文章编号: N19120505
期刊: Journal of Environmental Management
作者: Umeed Ali, Muhammad Shaaban, Saqib Bashir, Qingling Fu, Jun Zhu, Md Shoffikul Islam, Hongqing Hu
更新时间: 2019-12-05
摘要: Metals that contaminate soil is one of the major problems seriously affecting sustainable agriculture worldwide. Nickel (Ni) toxicity to agricultural crops is a global problem. Mobility of heavy metals present in contaminated soil can be reduced by the amendment of soil passivators, which will ultimately reduce the risk of them entering the food chain. A greenhouse pot experiment was conducted to investigate the effects of rice straw (RS), biochar derived from rice straw (BI) and calcium carbonate (calcite) on Ni mobility and its up take by maize (Zea maize L.) plant. Maize crop was grown in Ni spiked (100 mg kg⁻¹) soil with three application rates of passivators (equivalent to 0, 1and 2% of each RS, BI and calcite) applied separately to the soil. Results revealed that the post-harvest soil properties (pH, DOC and MBC), plant phenology (plant height, root length, total dry weight) and physiological characteristics were significantly enhanced with passivator application. Additionally, incorporating passivator into the soil reduced Ni mobility (DTPA) by 68%, 88.9% and 79.3%, and leachability (TCLP) by 72.4%, 76.7% and 66.7% for RS, BI and calcite, respectively at 2% application rate. The Ni concentration in the maize shoots reduced by 30%, 95.2% and 95% and in the roots by 56%, 66% and 63.8% with RS, BI and calcite at 2% application rate, respectively. These findings suggest that the application of 2% biochar (BI) is very promising in reducing Ni uptake, and can reduce toxicity to plants, decrease mobility and leachability in the soil.
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25730. 题目: Influence of saprophytic fungi and inorganic additives on enzyme activities and chemical properties of the biodegradation process of wheat straw for the production of organo-mineral amendments
文章编号: N19120504
期刊: Journal of Environmental Management
作者: Jorge Medina, Carlos M. Monreal, Luis Orellana, Marcela Calabi-Floody, María E. González, Sebastián Meier, Fernando Borie, Pablo Cornejo
更新时间: 2019-12-05
摘要: Cellulose and lignin as main components of crop residues have a significant influence on composting operations and composition of the final products. Both are strongly associated, and lignin can be considered an important barrier during the biodegradation process of lignocellulosic materials. Saprophytic fungi are efficient lignin degraders due to their complex enzymatic system. Therefore, the influence of the inoculation of saprophytic fungi (Coriolopsis rigida, Pleurotus ostreatus, Trichoderma harzianum and Trametes versicolor) and the supply of inorganic additives (Al₂O₃, Fe₂O₃ and allophanic soil) that promote the stabilization of carbon (C), were analyzed in the biodegradation of wheat straw (WS). The activity of Laccase (LAC), manganese peroxidase (MnP) and β-glucosidase and changes in temperature, pH and E₄/E₆ ratio were analyzed in a biodegradation process of 126 days. The activity of LAC, MnP and the E₄/E₆ ratio were significantly influenced and increased (enzymes) by fungi species, inorganic additives, and time of inorganic material addition, as well as their interactions (p < 0.05). The WS inoculated with T. versicolor showed the highest average activities for LAC, MnP and β-glucosidase (2000, 220 UL⁻¹ and 400 μmol pNP g⁻¹ h⁻¹ respectively). Furthermore, the addition of Al₂O₃ and Fe₂O₃ increased all the activities regarded to the decomposition of WS and influenced the changes associated with the stabilization of OM in composted WS. In conclusion, the inoculation of WS with T. versicolor in combination with metal oxides improved the enzyme related to the biodegradation process of WS favorizing its stabilization in the medium time, which is of importance in the composting of residues with high C/N ratio.

25731. 题目: Mercury geochemistry of deep-sea sediment cores from the Kuril area, northwest Pacific
文章编号: N19120503
期刊: Progress in Oceanography
作者: Kirill I. Aksentov, Valentina V. Sattarova
更新时间: 2019-12-05
摘要: In the present study we report mercury data in the sediment cores obtained during a Germany-Russian and Russian-Germany cruises onboard the Vessels Sonne and Akademik M.A. Lavrentyev in Kuril area. This region cover an extensive area of the Northwest Pacific included the trench system and adjacent abyssal plain, ranging zone off the Kuril Islands. Kuril area is characterized by high water biological productivity, intensive volcanic activity, and hydrological features. Mercury concentrations in sediment cores were analyzed using a Zeeman atomic absorption spectrometer with high frequency modulation of light polarization and a pyrolysis attachment to determine its occurrence, distribution, and deposition flux. Mercury concentrations in the sediments ranged between 8–170 ppb; its minimal concentrations (8–15 ppb) were detected in sandy turbidites. For the pre-industrial period, Hg flux ranged between 33–36 µg/m² year. The maximum Hg flux (44 µg/m² year) corresponded to the 1980, with decreases of up to 30 µg/m² year in modern sediments (top-core sediment samples). The Hg outlet temperature in the bottom sediments corresponded to a physically sorbed form of Hg and depends on the Hg content of diatoms (siliceous residues). Hg concentrations were significantly positivly correlated with total organic carbon content but negativly correlated with Al, Fe, Zr, and Sr contents. Thus, two main factors affected Hg burial in bottom sediments; atmospheric deposition of Hg and biological productivity. The effect volcanic activity has not been clearly established in this study.

25732. 题目: Soil microbial community responses to labile organic carbon fractions in relation to soil type and land use along a climate gradient
文章编号: N19120502
期刊: Soil Biology and Biochemistry
作者: Paulina B. Ramírez, Sebastián Fuentes-Alburquenque, Beatriz Díez, Ignacio Vargas, Carlos A. Bonilla
更新时间: 2019-12-05
摘要: There has been a growing interest in studying the labile C pool in order to promote the sequestration and stabilization of soil organic carbon (SOC). Although labile SOC fractions have emerged as standardized indicators because of their potential to detect early SOC trends over time, the relationships between microbial attributes and labile SOC remains poorly understood. In this study, we explored the influence of labile SOC fractions on the topsoil bacteria-archaea community across 28 sites with different land use, climate aridity, and soil types across a wide range of SOC content (0.6–12%) in central Chile. We applied Illumina sequencing to the 16S rRNA to examine shifts in the diversity and composition of these soil microbial communities. Additionally, labile SOC fractions such as the permanganate oxidizable carbon (POXC) and light fraction organic matter (LFOM), along with the soil physicochemical properties were analyzed. The results demonstrated that among all of the environmental factors tested, the pH, POXC/SOC ratio and LFOM were key drivers of microbial community structure (β-diversity). The α-diversity metrics exhibited a decreasing trend when aridity increased, and community structure was found to vary, with high POXC/SOC in sites associated with drier conditions. In addition, POXC/SOC ratios and LFOM were clearly related to shifts in the relative abundances of specific taxonomic groups at genera level. When there was high POXC/SOC and low LFOM content, members of Bacteroidetes (Adhaeribacter, Flavisolibacter, and Niastella), Proteobacteria (Skermanella, Ramlibacter, and Sphingomonas), and Archaea (Thaumarchaeota) were found to be the most dominant groups; however, the microbial taxa responded differently to both labile C fraction types. These results have implications for understanding how labile C content can potentially be used to predict shifts in the microbial community, thus facilitating the development of predictive ecosystem models, as well as early warning indicators for soil degradation.
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25733. 题目: Using stable isotope labeling approach and two dimensional correlation spectroscopy to explore the turnover cycles of different carbon structures in extracellular polymeric substances
文章编号: N19120501
期刊: Water Research
作者: Tahir Maqbool, Jinwoo Cho, Kyung Hoon Shin, Jin Hur
更新时间: 2019-12-05
摘要: Extracellular polymeric substances (EPS) from activated sludge comprise many organic constituents with polysaccharides and proteins as the main components of two different functionalities. Despite a number of previous EPS studies, a fundamental question remained unanswered, namely, whether the different EPS components would have the same turnover cycle (i.e., formation/dissolution) in biological wastewater treatment systems. In this study, we employed a stable isotope labeling approach based on isotope-enriched substrates (i.e., ¹³C-glucose and ¹⁵NH₄Cl) to examine the potential discrepancies in the turnover cycles among different major EPS constituents. Our results, based on substrate consumption in a batch bioreactor, evidenced the existence of differences in carbon and nitrogen cycles within bulk EPS with an earlier replenishment of organic carbon relative to organic nitrogen. The changes in the 13C nuclear magnetic resonance (13C NMR) spectra of EPS with operation clarified the relative differences in the turnover periods among several identified EPS structures with different chemical functionalities. Two-dimensional correlation spectroscopy (2D-COS) on the 13C NMR spectra further showed that the substrate-assimilated carbon functional groups appear to preferably formed within bulk EPS in the order of O-alkyl carbons > amides > α amino acids > aliphatic carbons. This study provides a novel insight into the dissimilar formation rates of different EPS structures after substrate assimilation. This isotope labeling approach can be further applied to determine the mass balance among the substrate, biomass, and bound/soluble EPS within activated sludge systems.
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25734. 题目: Contribution of Peatland Permafrost to Dissolved Organic Matter along a Thaw Gradient in North Siberia
文章编号: N19120408
期刊: Environmental Science & Technology
作者: Laure Gandois, Alison May Hoyt, Christine Hatté, Laurent Jeanneau, Roman Teisserenc, Marine Liotaud, Nikita Tananaev
更新时间: 2019-12-04
摘要: Permafrost peatlands are important carbon stocks currently experiencing rapid evolution after permafrost thaw. Following thaw, dissolved organic matter (DOM) is a potentially important pathway for the release of permafrost carbon. This study investigates the origin and composition of DOM across sites at different stages of thaw in a discontinuous permafrost area of North Siberia. We determine the optical properties, molecular composition, and stable isotopic (δ13C) and radiocarbon (14C) contents of DOM. Early stages of thaw are characterized by high DOC concentrations, high aromaticity, contribution of vegetation-derived DOM, and a high contribution of permafrost carbon. In contrast, in later stages, the microbial contribution to DOM increases, and only modern carbon is detected. This work links DOM composition with its radiocarbon content in permafrost peatlands. It shows that DOM originating from previously frozen permafrost peatlands is highly aromatic and previously processed. It highlights the variability of post-thaw carbon dynamics in boreal and arctic ecosystems.

25735. 题目: Association of dissolved organic matter characteristics and trace metals in mountainous streams with sabo dams
文章编号: N19120407
期刊: Environmental Science and Pollution Research
作者: Susan Praise, Hiroaki Ito, Kazuya Watanabe, Atsushi Sasaki, Toru Watanabe
更新时间: 2019-12-04
摘要: Metals undergo various processes transforming from one phase to another during transportation from head streams to oceans. The major chemical processes in the streams and rivers appear to be strongly dependent on dissolved organic matter (DOM). The mutualistic interactions between DOM and metals are important in determining the fate of many elements. We collected surface water samples from four stations along two mountainous streams in 2015 and analysed DOM quality and quantity and metal concentrations with the aim of understanding how changes in DOM characteristics are associated with dissolved metals along the stream with sabo dams. Both DOM and metal concentration were very low at the upstream site and did not show any significant correlation. However, sites within the dam vicinity (St.2 and St.3) had significantly high concentrations of manganese (Mn) and iron (Fe) which strongly correlated with molecular weight and aromaticity (> 0.6, p ≤ 0.01). Fe, Mn, copper (Cu) and aluminium (Al) significantly varied (p ≤ 0.05) downstream with highest average concentration for Al (17.7 ± 6.0 μg/L) and Cu (0.63 ± 0.3 μg/L). Cu had significant correlation with fluorescence components (fulvic-like, humic-like and protein like) and fluorescence index, while Fe significantly correlated to coloured DOM properties for all the sites. In the midstream section, strong correlations were exhibited by Fe, Cu, Zn and Mn whereas all metals did not show any significant correlation in the upstream site. Additionally, Cu, Mn and lead (Pb) showed strong correlation to DOM properties at the downstream site. The Fe to DOC and Mn to DOC ratios gave significant correlations with aromaticity, molecular weight and fulvic-like component at the midstream sections whereas Cu to DOC ratio lacked significant correlations to DOM at all the stations. Sabo dams enhanced Fe and Mn dissolution, while human activities in the downstream impacted Cu, Al, DOC, Mn and Fe stream concentrations. On the other hand, Fe and Mn were closely associated to DOM properties in regions of changing decreasing redox potential. The significant correlations presented by Mn, Fe and Cu with fluorescence index stresses the role of DOM heterogeneity in natural environments

25736. 题目: Nano-biochar reduced soil erosion and nitrate loss in sloping fields on the Loess Plateau of China
文章编号: N19120406
期刊: CATENA
作者: Xiaopeng Chen, Beibei Zhou, Quanjiu Wang, Wanghai Tao, Henry Lin
更新时间: 2019-12-04
摘要: The effects of biochar on soil erosion and nutrient loss on the Chinese Loess Plateau have been well reported, but the huge required application rate of biochar limits the biochar use. The specific nano-treatment can improve the distribution and properties of biochar (e.g., increase the specific surface area). To investigate the migration processes of runoff, sediment and nutrients on the nano-biochar (NB) applied sloping land during rainfall events, different mass content of NB (0.0%, 0.1%, 0.5%, 0.7%, and 1.0%) were used on the three types of vegetation covered sloping land (bare, caragana, and maize). The effects of NB and vegetation on runoff volume, sediment yield, and nitrate loss were studied under simulated rainfall in the northeastern region of the Loess Plateau. The main results were as follows: the application of NB effectively reduced runoff (39.7–74.4%), sediment yield (8.9–41.8%), and nitrate loss (13.6–59.8%) in all treatments. Losses of nitrate in runoff and sediment were negatively correlated with increased content of NB (when NB application rate was 1.0%, the maximum nitrate loss in runoff and sediment were 27.43 and 6.25 mg, respectively). The equivalent model of convection was more suitable for analyzing the nutrient transfer process with the application of NB. The effective mixing depth decreased with NB content and could be well described by a power function. NB might promote the nitrate migrate to deep soil and reduce nitrate loss in runoff and sediment. With NB application, the peak value of nitrate distribution in the profile moved downward, and the maximum value was obtained at 10–15 cm. Moreover, the most effective NB content for reducing nitrate loss were 1.0%. Comparing with bare and maize, caragana had the most significant effect on reducing runoff, sediment and nutrient loss. In addition, Synergistic effect of NB and caragana showed the great potential on soil and water loss control. The findings in this study provide an efficient and economic method for controlling soil erosion and nutrient loss on the Chinese Loess Plateau.

25737. 题目: Soil conservation in an abandoned agricultural rain-fed land through inoculation of cyanobacteria
文章编号: N19120405
期刊: CATENA
作者: Hossein Kheirfam, Seyed Hamidreza Sadeghi, Behrouz Zarei Darki
更新时间: 2019-12-04
摘要: Newly abandoned rain-fed lands, due to soil quality decline, are the main sources for soil erosion in semi-dry lands agricultural hill-slopes. However, adopting compatible environmentally friend measures have not been adequately implemented. Following various resultful laboratory studies, in this paper, we assessed the effect of field inoculation of cyanobacteria in an abandoned rain-fed land on controlling the natural rainfall-induced soil loss and improving the biological soil crust (BSC) quality mixture of two cyanobacteria (viz. Nostoc sp. and Oscilatoria sp.). The cyanobacteria were inoculated on 22.1 m × 1.83 m-sized plots located on the study hill-slope. The experiment was carried out for a rainfall period of 6 months under natural conditions. Measurements of 7 erosive rainfalls showed a considerable soil loss (i.e., 0.88 ± 0.10 to 9.79 ± 1.60 g m⁻²) from the un-inoculated plots (control), while cyanobacteria decreased the soil loss by 36 to 57% in comparison with those recorded for the control. Soil losses in the inoculated plots were 2.39 ± 0.24, 4.8 ± 0.58, 3.32 ± 0.33, 1.49 ± 0.12, 0.87 ± 0.12, 0.52 ± 0.05, and 0.56 ± 0.08 g m⁻², from the first to last rainstorms, respectively. Our results, therefore, showed a poor linear relationship between soil loss (from both treatments) and rainfall properties. Cyanobacteria also improved organic carbon and nitrogen contents as two important BSC quality indicators to the tunes of 32 and 56%, respectively, in comparison to the control, during the study period. In winter, when environmental conditions were inappropriate for growing vegetation, the effect of cyanobacteria on soil loss reduction was found to be more tangible in comparison with spring. On the whole, our field soil inoculation under uncontrolled conditions, as pioneering research, facilitated to promising results for large-scale use of cyanobacteria to rapidly restore abandoned rain-fed lands.
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25738. 题目: A cascading influence of calcium carbonate on the biogeochemistry and pedogenic trajectories of subalpine soils, Switzerland
文章编号: N19120404
期刊: Geoderma
作者: Mike C. Rowley, Stephanie Grand, Thierry Adatte, Eric P. Verrecchia
更新时间: 2019-12-04
摘要: Soil research in temperate to cool and humid regions has typically focused on acidic soils; there has been relatively little investigation of the effects of calcium carbonate (CaCO₃) on unamended soil properties or function in these environments. The object of this study was to characterise the effects of small amounts of CaCO₃ on pedogenic trajectories and soil biogeochemistry in a humid subalpine valley of Switzerland. To isolate the influence of CaCO₃, six profiles were selected that had developed under almost identical conditions for soil formation, i.e. climate, topography, vegetation structure, time since deglaciation, silicate mineralogy and texture. The main difference between the profiles was that three contained a small quantity of CaCO₃ (<6.2%; thereafter, ‘CaCO₃-bearing’) while the remaining three contained no detectable CaCO₃ (thereafter, ‘CaCO₃-free’). The presence of CaCO₃ was associated with cascading changes in soil biogeochemistry. These changes included higher pH, an order of magnitude higher extractable Ca and twice as much soil organic carbon (SOC). CaCO₃-bearing profiles also displayed a higher proportion of poorly crystalline Fe forms. The higher pH at the CaCO₃-bearing site was attributable to the weak buffering provided by CaCO₃ dissolution, which in turn maintained the relatively higher extractable Ca. Exchangeable Ca (Ca_Exch) and other reactive Ca forms could help stabilise SOC, contributing to its accumulation through processes such as flocculation and subsequent occlusion within aggregates and/or sorption to mineral surfaces. The increased SOC, Ca_Exch and pH at the CaCO₃-bearing site could in turn be inhibiting the crystallisation of disordered Fe forms, but further research is required to confirm this effect and isolate the exact mechanisms. Overall, this study shows that the presence of small amounts of CaCO₃ in humid environments has a far-reaching influence on soil biogeochemistry and further supports the idea that indicators of Ca prevalence have the potential to improve regional SOC estimates.
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25739. 题目: Biochar phosphorus fertilizer effects on soil phosphorus availability
文章编号: N19120403
期刊: Chemosphere
作者: Haixiao Li, Yuxin Li, Yan Xu, Xueqiang Lu
更新时间: 2019-12-04
摘要: Biochar is a potential material for making slow-releasing phosphorus (P) fertilizers for the sake of increasing soil P use efficiency and mitigating P losses. However, the long-term effects of P-laden biochars on soil P availability remains unconcerned. In this study, a laboratory-scale 70-days soil incubation experiment was conducted to study the effects of original and P-laden biochars on soil P availability and fractions. Two original biochars were derived from maize stalks by pyrolyzing at 350 °C and 600 °C. P was laden on those biochars by immersing biochars in saturated KH₂PO₄ solution for 24 h. Eight treatments were set for the incubation experiment, which were soil, soil + triple-superphosphate (TSP), soil + 350 °C biochar, soil + 600 °C biochar, soil + TSP + 350 °C biochar, soil + TSP + 600 °C biochar, soil + 350 °C P-laden biochar, and soil + 600 °C P-laden biochar. Results showed that original biochars could decrease soil available P through P adsorption. And there were no significant differences of soil P fractions under the treatments of mineral P fertilizer and P-laden biochars. Whereas, compared to mineral P fertilizer, P-laden biochars, especially 600 °C P-laden biochar, could maintain soil available P in a significantly higher level across the incubation. It was mainly because of the slow-releasing pattern of P laden on biochar and a more homogeneous soil P source distribution under P-laden biochar treatments. These results indicated that P-laden biochar could work as P fertilizer to improve soil P use efficiency.

25740. 题目: Degradation behaviors of Isopropylphenazone and Aminopyrine and their genetic toxicity variations during UV/chloramine treatment
文章编号: N19120402
期刊: Water Research
作者: Bingqi Jiang, Yajun Tian, Zichen Zhang, Ze Yin, Li Feng, Yongze Liu, Liqiu Zhang
更新时间: 2019-12-04
摘要: Combination of ultraviolet and chloramine (i.e., UV/chloramine) treatment has been attracting increasingly attention in recent years due to its high efficiency in removing trace organic contaminants. This study investigated the degradation behaviors of two pyrazolone pharmaceuticals (i.e., Isopropyl phenazone (PRP) and Aminopyrine (AMP)) and their genetic toxicity variations during UV/chloramine treatment. The results showed that chloramine could hardly degrade PRP and AMP, while UV/chloramine greatly increased the observed first-order rate constant (k_obs) of PRP and AMP degradation. The quenching and probe experiments illustrated that the reactive chlorine species (RCS) contributed dominantly to PRP removal, and hydroxyl radical (HO^•) was the major contributor to the degradation of AMP, while the reactive amine radicals (RNS) could hardly degrade them. The overall degradation rates of PRP and AMP decreased as pH increased from 6.5 to 10. The k_obs of PRP and AMP increased along with NH₂Cl dosage increasing and reached a plateau at higher concentrations (0.2–0.5 mM). The present background carbonate (HCO₃⁻, 1–10 mM), chloride (Cl⁻, 1–10 mM) and natural organic matter (NOM, 5-10 mg-C L⁻¹) exhibited inhibition impacts on PRP and AMP degradation. In addition, the intermediates/products of PRP and AMP were identified and their general degradation pathways were proposed to be hydroxylation, deacetylation, and dephenylization. Specifically, Cl-substitution was inferred during PRP degradation, while demethylation in tertiary amine group was only observed in AMP degradation. These mechanisms including the main reactive sites of PRP and AMP were further confirmed by the frontier orbitals calculation. Moreover, the results of the genetic toxicity according to the micronucleus test of Viciafaba root tip indicated that UV/chloramine treatment could partially reduce the genetic toxicity of PRP and AMP.
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