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25861. 题目: A comprehensive probabilistic approach for integrating natural variability and parametric uncertainty in the prediction of trace metals speciation in surface waters
文章编号: N18080811
期刊: Environmental Pollution
作者: P. Ciffroy, M. Benedetti
更新时间: 2018-08-08
摘要: The main objectives of this study were to evaluate global uncertainty in the prediction of Distribution coefficients (Kds) for several Trace Metals (TM) (Cd, Cu, Pb, Zn) through the probabilistic use of a geochemical speciation model, and to conduct sensitivity analysis in speciation modeling in order to identify the main sources of uncertainty in Kd prediction. As a case study, data from the Loire river (France) were considered. The geochemical speciation model takes into account complexation of TM with inorganic ligands, sorption of TM with hydrous ferric oxides, complexation of TM with dissolved and particulate organic matter (i.e. dissolved and particulate humic acids and fulvic acids) and sorption and/or co-precipitation of TM to carbonates. Probability Density Functions (PDFs) were derived for physico-chemical conditions of the Loire river from a comprehensive collection of monitoring data. PDFs for model parameters were derived from literature review. Once all the parameters were assigned PDFs that describe natural variability and/or knowledge uncertainty, a stepwise structured sensitivity analysis (SA) was performed, by starting from computationally ‘inexpensive’ Morris method to most costly variance-based EFAST method. The most sensitive parameters on Kd predictions were thus ranked and their contribution to Kd variance was quantified. Uncertainty analysis was finally performed, allowing quantifying Kd ranges that can be expected when considering all the sensitive parameters together.
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25862. 题目: Impact of microbial activity on the mobility of metallic elements (Fe, Al and Hg) in tropical soils
文章编号: N18080810
期刊: Geoderma
作者: C. Balland-Bolou-Bi, E.B. Bolou-Bi, V. Alphonse, S. Giusti-Miller, M.D. Jusselme, A. Livet, M. Grimaldi, N. Bousserhine
更新时间: 2018-08-08
摘要: Dissolved organic carbon (DOC), especially low molecular mass organic acids (LMMOAs) derives principally from biota degradation process in which soil microorganisms are the main actors and from roots exudates. The presence of LMMOAs led to an increase of availability and mobility of metallic elements through the formation of organo-metallic complex. In tropical soils, very few information about LMMOAs quantification and their role in the biogeochemical process related to trace metals cycling was available. Quantification of LMMOAs is limited due to their low concentration and rapid degradation. Until now, the role of microbial activity as well as LMMOAs in the biogeochemical cycle of metallic elements in tropical soils has not been investigated. The present study was conducted to evaluate the effect of microbial activity and biomass on the availability and mobility of metallic elements (Fe, Al and Hg) in two tropical soils, Ferralsol and Acrisol. We also quantified LMMOAs contents in soil solutions and addressed to their role in the mobilization of metals.Utilization of Diffuse Gradient in Thin film (DGT) method permits to analyze bioavailable metal in both fractions: organically complexed and free metals. The results show that the quantity of Fe, Al and Hg labile were higher in Ferralsol than Acrisol soils. This was more accentuated for the 50 cm-depth of soils where the microbial activities and the organic carbon content were important. Concentration of LMMOAs of Ferralsol and Acrisol were lower in compare to coniferous and deciduous forest soils. Proportions of LMMOAs in DOC were very small at 10.5% and 6.85% in the Ferralsol and Acrisol soils, respectively. The mobilization of Fe, Al and Hg in Ferralsol and Acrisol soils appeared to vary depending on the soil physico-chemical characteristics (sorption capacities and metals content) and also on the microbial biomass and activity. Soil pH influences the acidity of the functional groups in organic molecules and consequently their speciation. In addition, low pH increase proton competition within acidic functional groups involved in coordinate bond. The content of CEC in Ferralsol is higher than Acrisol that is related to the high contents of clay and organic carbon. Low CEC content can result in a decrease of retain of the cationic trace metals. Low CEC content led to a decrease of the capacity of retaining of metallic elements in tropical soils in compare to temperate soils.

25863. 题目: Baseline map of soil organic carbon in Tibet and its uncertainty in the 1980s
文章编号: N18080809
期刊: Geoderma
作者: Y. Zhou, R. Webster, R.A. Viscarra Rossel, Z. Shi, S. Chen
更新时间: 2018-08-08
摘要: Much of the carbon (C) stored in the soil of the high Qinghai–Tibet Plateau could be lost as a result of global warming. To provide a baseline against which to assess the loss we have made a new map at 90-m resolution from sample data of 1148 soil profiles augmented by information on climate, vegetation, physiography and digital elevation. We used the program Cubist, which works as a form of regression tree, to predict the concentration at the nodes of the 90-m grid. The uncertainty of the predictions was computed by bootstrapping 50 times at each node. Soil type, evapotranspiration (ET), precipitation, radiation and vegetation type contributed most to the variation in C at the coarse scale; temperature, net primary productivity, normalized difference vegetation index (NDVI), ET and elevation contributed most at finer scales. We mapped the predicted concentration of C and converted the predictions to stocks of C for the main kinds of land: 1.93 Pg for the alpine steppe, 1.57 Pg for the meadow, 0.66 Pg in the coniferous forest, 0.63 Pg in the broadleaf forest, 1.06 Pg under shrub, < 0.4 Pg for each of the alpine desert and cropland. We estimate the uppermost 30 cm of soil to contain 6.81 Pg of C with 95% (3.80 to 10.27 Pg). This estimate differs substantially from the two previous coarser estimates based on global modelling which far exceed our 95% upper confidence limit. Our new estimate can now serve as a base against which to judge any change of soil C as a response to global warming.

25864. 题目: Environmental safety data on CuO and TiO₂ nanoparticles for multiple algal species in natural water: Filling the data gaps for risk assessment
文章编号: N18080808
期刊: Science of The Total Environment
作者: Elise Joonas, Villem Aruoja, Kalle Olli, Anne Kahru
更新时间: 2018-08-08
摘要: Most research on nanoparticle (NP) ecotoxicological effects has been conducted on single species in laboratory conditions that are not environmentally representative. We compared the effects of CuO NPs, CuSO₄ (ionic control) and TiO₂ NPs in nutrient-adjusted natural water (ANW) and in the OECD201 standard medium to four different algal species: green algae Raphidocelis subcapitata and Chlamydomonas reinhardtii, a diatom Fistulifera pelliculosa, and a cyanobacterium Synechocystis sp. Biomass and the effective quantum yield of photosystem II (Fv/Fm) were used as toxicity endpoints. CuO NPs were very toxic across taxa in the OECD201 assay (biomass-based 72 h EC₅₀ 0.2–0.9 mg l⁻¹). Toxicity of CuO NPs was explained by shedding of ions from particles as Cu²⁺ is highly toxic: 72 h EC₅₀ in the OECD201 medium was 0.01–0.03 mg l⁻¹ in three species and 0.003 mg l⁻¹ in the case of the cyanobacterium. Toxicity of copper compounds was overall reduced in ANW, presumably because of reduced bioavailability due to metal ions binding to natural organic matter. Copper compounds were more toxic to the cyanobacterium than to other algae and this effect was not amended in ANW. TiO₂ NPs did not inhibit the biomass production and photosynthesis of the diatom or the cyanobacterium up to 100 mg l⁻¹, but inhibited biomass production of green algae in the OECD201 medium (EC₅₀ 14–15 mg l⁻¹). TiO₂ NPs also did not significantly inhibit Fv/Fm up to 100 mg l⁻¹, suggesting a general lack of effect on photosynthesis. Adverse effects of TiO₂ NPs were at least in part due to cell-NP heteroagglomeration. Our data are informative for the complete risk assessment of engineered NPs by filling data gaps about NP effects in environmentally realistic conditions.
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25865. 题目: The impact of woodchip-gravel mixture on the efficiency and toxicity of denitrification bioreactors
文章编号: N18080807
期刊: Science of The Total Environment
作者: Michal Šereš, Klára Anna Mocová, Jabbar Moradi, Michal Kriška, Vladimír Kočí, Tereza Hnátková
更新时间: 2018-08-08
摘要: Woodchip-based denitrification bioreactors are widely used for treatment of high loads of nitrate pollution in agricultural run-off water. A concern raised recently, as a consequence of various organic fillings being experimented with, is whether the positive effect given by nitrate reduction could override the negative effects of such bioreactors, mainly caused by degradation of wood and the production of potentially harmful conditions for aquatic ecosystems. This paper presents the results of the experimental testing of two different filling materials: birch (BWCH) and spruce (SWCH) woodchip, and their mixture with washed gravel (WG) in volumetric ratio 10:1. We have focused on the leaching of organic carbon and phenols, and its impact on selected aquatic organisms, as well as on their denitrification efficiency and NO₃⁻ load removal rate (LRT). The results show that TOC, DOC and FNI (phenolic index) leaching is higher for the pure woodchip materials and is closely correlated with the growth inhibition of tested organisms (Vibrio fischeri, Daphnia magna, Desmodesmus subspicatus, Lemna minor). The highest denitrification efficiency and the highest load removal rates were recorded in mixed filling material (96% and 1.4 mg NO₃⁻·dm³·d⁻¹ for WG:BWCH; 85% and 1.2 mg NO₃⁻·dm³·d⁻¹ for WG:SWCH). Denitrification bioreactors with mixed woodchip filling material present a promising, cheap, and extensive technology for the treatment of agricultural field run-offs.
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25866. 题目: Distributions and pools of lead (Pb) in a terrestrial forest ecosystem with highly elevated atmospheric Pb deposition and ecological risks to insects
文章编号: N18080806
期刊: Science of The Total Environment
作者: Jun Zhou, Buyun Du, Zhangwei Wang, Wantong Zhang, Lei Xu, Xingjun Fan, Xiaoli Liu, Jing Zhou
更新时间: 2018-08-08
摘要: There is growing interest in how heavy metals in remote ecosystems are elevated and affect environmental health. However, no studies have investigated atmospheric lead (Pb) deposition influences on the Pb bioaccumulation in insects in forests. Here we measure Pb concentrations and pools in forest vegetation, litterfall, organic soil, mineral soil, as well as litterfall deposition fluxes in a region severely affected by atmospheric deposition. We also analyzed Pb in insects which feed in the polluted forest vegetation and litter. Assessment of high Pb loads causing potential ecological risk to insects was also studied. Total Pb pool in the vegetation was 0.12 g m⁻² and annual litterfall deposition flux of Pb was 13.42 mg m⁻², which was much higher than those in the background areas. Pools of Pb from litter to mineral topsoil averaged 4.3 g m⁻², which accounted for 97.3% of total pools (biomass + soil) in the forest ecosystem. Pools of Pb in surface soils were correlated significantly with the pools of total organic matter and elevation. Atmospheric deposition was inferred the major source of Pb in the forest ecosystem, which can be supported by the highest Pb concentrations in the moss and overstory foliage. The maximum Pb concentration was showed in the dung beetle (12.1 mg kg⁻¹) residing in the soils compared that in the longicorn and of cicada, which would potentially pose negatively influence to predators along food chains.
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25867. 题目: Assessment of fungi proliferation and diversity in cultural heritage: Reactions to UV-C treatment
文章编号: N18080805
期刊: Science of The Total Environment
作者: Stéphane Pfendler, Battle Karimi, Laurence Alaoui-Sosse, Faisl Bousta, Badr Alaoui-Sossé, Mohamed M. Abdel-Daim, Lotfi Aleya
更新时间: 2018-08-08
摘要: Fungi are present in natural and non-touristic caves due to the presence of organic matter provided mainly by insects or animals such as bats. In show caves, however, tourist infrastructure and the visitors themselves are an important source of organic matter. In addition, photosynthetic biofilms provide a high amount of carbon and nitrogen sources for fungi. This study was conducted to identify the fungal communities present in caves along with the potential use of UV-C treatment against their proliferation. Thus, fungal communities proliferating in biofilms in six French and Swiss show caves were analyzed using high throughput sequencing. The results show 385 species recorded, some of them previously described in cases of fungal outbreak. This preliminary study also aimed to test the use of UV-C light as an environmentally friendly method to treat fungal proliferation. Six fungal strains, from three different sources (Lascaux cave, La Glacière cave, a church in Vicherey, France), were cultivated in an agar dish. Spores, mycelia and the entire colony were irradiated using several UV-C intensities. Results showed that four of the six fungi spores and mycelium died following a low-intensity UV-C treatment (2 kJ m⁻², 160 s), though Ochroconis lascauxensis and Penicillium bilaiae spores showed higher resistance. Finally, it was demonstrated that the fungal colony could resist the UV-C light due to a shadow effect. The structure of the fungal colony was affected from the periphery to its inner part. However, after four 30 kJ m⁻² treatments (39 min irradiation) all strains there definitively eradicated. Further studies will be necessary to examine the potential of UV-C light under cave conditions as a preventive and curative treatment.
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25868. 题目: Reactive Photo-Fenton ceramic membranes: Synthesis, characterization and antifouling performance
文章编号: N18080804
期刊: Water Research
作者: Shaobin Sun, Hong Yao, Wanyi Fu, Likun Hua, Guangshan Zhang, Wen Zhang
更新时间: 2018-08-08
摘要: To develop reactive and antifouling membrane filtration systems, a photo-Fenton ceramic membrane was prepared by coating goethite (α-FeOOH) catalysts on a zirconia/titania alumina membrane via a cross-linking method. Scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to characterize α-FeOOH catalysts and the surface coating quality. The cross linker yielded stable covalent binding between catalyst and membrane under room temperature and produced a homogeneous and smooth coating of catalyst on ceramic membranes. Photo-Fenton reactions were initiated with addition of H₂O₂ under UV irradiation to improve the foulant degradation on membrane surface while filtration. Membrane fouling was simulated by bovine serum albumin (BSA) and humic acid (HA). Our results show that the photo-Fenton reactions on the coated membranes slowed down the fouling kinetics and even reversed the fouling, leading to a stable transmembrane pressure (TMP) over time of filtration, as opposed to a monotonous increase of TMP due to surface fouling. The batch experiments verified that the photo-Fenton reactions achieved the degradation rates of 76% and 86% for HA and BSA respectively within 60 min, with the mineralization rates of over 80% as indicated by the total organic carbon measurement. This study embarks on a novel antifouling membrane filtration process via incorporation of photo-Fenton reactions. The findings are also important for diverse applications of surface fouling mitigation and rationale design of fouling resistant surfaces or materials through photo-Fenton or other catalytic reactions.
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25869. 题目: Electrochemical filtration process for simultaneous removal of refractory organic and particulate contaminants from wastewater effluents
文章编号: N18080803
期刊: Water Research
作者: Naresh Mameda, Hyeona Park, Kwang-Ho Choo
更新时间: 2018-08-08
摘要: Versatile electrochemical reactions are effective for removing a wide range of water contaminants. This study focuses on the development and testing of bifunctional electrocatalytic filter anodes as reactive and separating media for the simultaneous removal of refractory dissolved organic and particulate contaminants from real wastewater effluents. The results show that the TiO₂ particle interlayers formed between the Ti fiber support and the top composite metal oxide catalyst layers assist in reducing filter pores to an effective size range that enables removal of most particulates within the wastewater. The double-sheet design, which is a sandwich-structured module with an internal void space for permeate, prevents filter fouling, and transmembrane pressure can be maintained at a very low level of <5 kPa during batch and continuous flow reactor operations. Substantive and simultaneous removal of dissolved organics (e.g., chromophores, fluorophores, 1,4-dioxane, chemical oxygen demand, and total organic carbon) and particulate matter (i.e., turbidity) are achieved, although removal rates and efficacies differ depending on the electric current density applied. Decolorization and particulate rejection occur swiftly and immediately, but 1,4-dioxane degradation is relatively slow and quite time-dependent. Possible 1,4-dioxane degradation pathways during electrocatalysis are also proposed. Electrochemical filtration technology shows considerable promise for use in the next generation of advanced wastewater treatment solutions.
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25870. 题目: Influence of polysaccharides on the dynamic self-assembly of medium-chain fatty acid vesicles and hydrolysis of decanoic acid anhydrides
文章编号: N18080802
期刊: Colloids and Surfaces A: Physicochemical and Engineering Aspects
作者: Ming-Qiang Jia, Qi-Zheng Liu, Li-Juan Zhu, Yan Zhang, Zhong-Xiu Chen
更新时间: 2018-08-08
摘要: Hydrolysis of fatty acid anhydrides involves fatty acid vesicle formation and autocatalytic hydrolysis. Previous studies focused on the effect of biopolymers on vesicle formation or on autocatalytic reactions, however, the influence of polysaccharides on a system where the self-assembly of fatty acid vesicles and the hydrolysis of fatty acid anhydrides coexist remains unknown. In this paper, three polysaccharides, sodium chondroitin sulfate (CSA), sodium alginate (SA) and 2-hydroxyethyl cellulose (2-HEC) were selected to investigate the effect of crowded media on the decanoic acid vesicle formation and the autocatalytic hydrolysis of decanoic anhydride. The results showed that the rate of hydrolysis of decanoic anhydride increased in CSA or SA but decreased in 2-HEC. Further investigation revealed that the size of vesicles in CSA decreased in the early stage of vesicle formation but increased in 2-HEC. In the CSA-vesicle system, elastic behavior dominates, while 2-HEC- and SA-vesicles show more viscous behavior. In addition, the significantly increased membrane fluidity in CSA or in SA supports self-assembly of decanoic acid vesicles and autocatalytic hydrolysis, which is the opposite in the case of 2-HEC. This research provides new insights into the self-assembly of fatty acid vesicles and vesicle-catalyzed reactions with polysaccharides in crowded conditions.
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25871. 题目: Remineralization rate of terrestrial DOC as inferred from CO2 supersaturated coastal waters
文章编号: N18080801
期刊: Biogeosciences
作者: Filippa Fransner, Agneta Fransson, Christoph Humborg, Erik Gustafsson, Letizia Tedesco, Robinson Hordoir, and Jonas Nycander
更新时间: 2018-08-08
摘要: Coastal seas receive large amounts of terrestrially derived organic carbon (OC). The fate of this carbon, and its impact on the marine environment, is however poorly understood. Here we combine underway CO₂ partial pressure (pCO₂) measurements with coupled 3D hydrodynamical-biogeochemical modelling to investigate whether remineralization of terrestrial dissolved organic carbon (tDOC) can explain CO₂ supersaturated surface waters in the Gulf of Bothnia, a subarctic estuary. We find that a substantial remineralization of tDOC, and that a strong tDOC induced light attenuation dampening the primary production, is required to reproduce the observed CO₂ supersaturated waters in the nearshore areas. A removal rate of tDOC of the order of one year, estimated in a previous modelling study in the same area, gives a good agreement between modelled and observed pCO₂. The remineralization rate is on the same order as bacterial degradation rates calculated from published incubation experiments, suggesting that this remineralization could be caused by bacterial degradation. Furthermore, the observed high pCO₂ values during the ice covered season argues against photochemical degradation as the main removal mechanism. All of the remineralized tDOC is outgassed to the atmosphere in the model, turning the northernmost part of the Gulf of Bothnia to a source of atmospheric CO₂.

25872. 题目: Compost Humic Acid-Like Isolates from Composting Process as Bio-based Surfactant: Properties and Feasibility to Solubilize Hydrocarbon from Crude Oil Contaminated Soil
文章编号: N18080712
期刊: Journal of Environmental Management
作者: Gina Lova Sari, Yulinah Trihadiningrum, Dwiyanti Agustina Wulandari, Ellina Sitepu Pandebesie, I.D.A.A. Warmadewanthi
更新时间: 2018-08-07
摘要: Biodecomposition of organic solid waste during composting process produces compost humic acid-like (cHAL), which is classified as biobased surfactant. The present study aimed to characterize the properties of cHAL substance which was formed during the composting process of crude oil contaminated soil, in terms of surface tension decline (∆ST) and emulsification activity (EA), and evaluate the ability to solubilize hydrocarbons. Crude oil contaminated soil from a public oilfield in Wonocolo Sub-district, Bojonegoro, Indonesia, was composted under aerobic condition with varied biodegradable waste (yard waste and rumen residue) in separate reactors. The cHAL compounds were isolated from composting products from yard waste (Y₁₀₀), rumen residue (R₁₀₀), control of contaminated soil (S₁₀₀), and mixed of contaminated soil and biodegradable waste (S₅₀YR₅₀). The results showed that ∆ST of cHAL isolates were ranged from 6.65 to 21.50 mN/m. The EA of cHAL isolates were in the range of 7.35–38.01%. The cHAL isolates were capable to solubilize 99 to 10,710 µg/g of hydrocarbons. The cHAL isolates from R₁₀₀ and S₅₀YR₅₀ are potential as surface tension reducer and emulsifier for hydrocarbon with values of those isolates were close to 0.50% Tween 80 characteristics, and the abilities to solubilize hydrocarbon were comparable to 1.00% Tween 80. A composition of 50% crude oil contaminated soil and 50% of biodegradable waste (yard waste and rumen residue) is recommended for composting crude oil contaminated soil.

25873. 题目: Prediction models for evaluating the uptake of heavy metals by cucumbers ( Cucumis sativus L.) grown in agricultural soils amended with sewage sludge
文章编号: N18080711
期刊: Environmental Monitoring and Assessment
作者: Ebrahem M. Eid, Sulaiman A. Alrumman, Emad A. Farahat, Ahmed F. El-Bebany
更新时间: 2018-08-07
摘要: Heavy metal (HM) concentrations in edible plants can develop many serious health risks to humans. The precise prediction of plant uptake of HMs is highly important. Thus, the present investigation was carried out to develop regression models for predicting the concentrations of HMs in cucumbers (Cucumis sativus L.) from their concentration in the soil and using the organic matter (OM) content and soil pH as co-factors. The results showed that cucumber roots had the highest significant concentrations of all HMs at P < 0.001, except Cd, Cu, and Zn were in fruits. The lowest concentrations of Cd, Co, Cr, Mn, Ni, and Pb were recorded in stems. HM concentrations in cucumbers were strongly correlated with soil HM, pH, and OM content. Soil pH and OM content had negative and positive correlations with all HMs in cucumber tissues, respectively. Regression analysis indicated that soil HM, pH, and OM contents were good predictors for HM concentrations in cucumbers. The regression models for root Co, Cr, Fe, and Zn were described by high model efficiency values that explain 48–58% variability. The best regression models for cucumber stem were for Cu, Mn, Ni, and Zn that are characterized by high R² and model efficiency values. For cucumber fruits, R² values were ranged from 54 to 82%, with best models for Cr, Pb, Cd, Cu, Ni, and Co in the fruit. We expect that these models will be beneficial for risk assessment studies on sewage sludge utilization in agriculture.

25874. 题目: Molecular biomarkers in the subsurface of the Salar Grande (Atacama, Chile) evaporitic deposits
文章编号: N18080710
期刊: Biogeochemistry
作者: Laura Sánchez-García, Christoph Aeppli, Victor Parro, David Fernández-Remolar, Miriam García-Villadangos, Guillermo Chong-Diaz, Yolanda Blanco, Daniel Carrizo
更新时间: 2018-08-07
摘要: The Late Miocene–Pliocene aged hyperarid evaporitic system of Salar Grande is a unique, halite-rich sedimentary basin in the Cordillera de la Costa of the Central Andes (Chile) whose bio-sedimentary record is poorly understood. The persistence of hyperacidity over millions of years, the hypersalinity, and the intense UV radiation make it a terrestrial analogue to assess the potential presence of organic matter in the halite deposits found on Mars. We investigated the occurrence and distribution of biomolecules along a 100-m depth drill down to the ~ 9 Ma old detrital deposits topped by La Soledad Formation (ESF). We have identified two well-defined mineralogical and geochemical units by X-ray diffractometry (XRD) and ion chromatography: a nearly pure halite down to 40 m, and a detrital one down to 100 m depth. One-dimensional GC–MS and two-dimensional GC × GC-TOF–MS gas chromatography–mass spectrometry techniques allowed us to detect a variety of lipidic compounds (n-alkanes, n-alkanols, isoprenoids, steroids, and hopanoids), and a relative abundance of functionalized hydrocarbons (n-fatty acids or n-aldehydes), mostly in the upper halite. We also detected biopolymers and microbial markers by fluorescence sandwich-microarray immunoassays. A dominant prokaryotic origin was associated with halophile bacteria and archaea, with minor contributions of lichens, macrophytes, or higher plants. The lipidic record was also imprinted by oxic (high pristane over phytane ratios) and saline (squalane, and mono-methyl n-alkanes) signatures. The vertical abundance and distribution of biomarkers in the Salar Grande was explained by a generalized effect of xeropreservation, combined with salt encapsulation in the upper halite deposits, or with protective organics-mineral interactions in the deeper detrital unit. The results contribute to the interpretation of terrestrial bio-sedimentary records of halite deposits and their association to environmental conditions. The high potential for preservation of biosignatures at Salar Grande suggests that similar evaporitic deposits in Mars should be priority targets for searching for signs of life.

25875. 题目: Influence of soil and water conservation measures on soil fertility in the Beijing mountain area
文章编号: N18080709
期刊: Environmental Monitoring and Assessment
作者: Hongli Mu, Suhua Fu, Baoyuan Liu, Bofu Yu, Aijuan Wang
更新时间: 2018-08-07
摘要: Soil and water conservation (SWC) measures can be adopted to conserve soil and water and improve soil fertility. The degree to which SWC measures improve soil fertility is affected by the type of SWC measure, soil type, climate, etc. The purpose of this study was to study the effect of the main SWC measures implemented in the Beijing mountain area on soil fertility. Six runoff plots, including a fish pit (fallow) (FPF), fish pit (Platycladus orientalis L. Franco) (FPP), narrow terrace (fallow) (NTF), narrow terrace (Juglans regia L.) (NTJ), tree pan (Juglans regia L.) (TPJ), and fallow land (FL), were established to analyze the differences in soil fertility in the Beijing mountain area. Soil samples were collected in 2005 and 2015 from the six runoff plots. Soil particle size; soil total nitrogen (TN), total phosphorous (TP), total potassium (TK), alkali-hydrolysable nitrogen (Ah-N), available P (Av-P), and available K (Av-K); and soil organic matter (SOM) were measured. The soil integrated fertility index (IFI) was calculated. The results showed that the soil nutrient content and IFI significantly decreased from 2005 to 2015 in the FL plot and significantly increased in the five runoff plots with SWC measures. Compared to the other runoff plots with SWC measures, the FPP plot more significantly improved the soil nutrient content and IFI. The TN, Ah-N, Av-K, SOM, and IFI in the FPP plots increased by 98%, 113%, 61%, 69 and 47%, respectively, from 2005 to 2015. The IFI for the FPP, NTJ, and TPJ exceeded the average IFI of the farmland soil in the study region. The results indicated that the combination of engineering practices and vegetative measures effectively improved soil fertility. These results may be helpful for selecting SWC measures, land-use planning and monitoring and assessing soil fertility.

25876. 题目: Effects of cover on soil particle and associated soil nutrient redistribution on slopes under rainfall simulation
文章编号: N18080708
期刊: Journal of Soils and Sediments
作者: Jiamei Sun, Chi-hua Huang, Guannan Han, Yafeng Wang
更新时间: 2018-08-07
摘要: Purpose: Sediment detachment, transportation, and deposition occurred alternately along slope during erosion process. Nutrients were mobilized with sediment movement. In this research, nutrients and fractal characteristics were analyzed on both bare and covered slopes. Then, combined with photogrammetry technique, soil elevation and associated soil nutrient redistribution on slope positions during rainfall event were explored. Materials and methods: Combined with simulated rainfall method, bare and covered slopes experienced erosion process. Fractal theory was used to analyze sediment particle size distribution. Photogrammetry technique was applied to locate sediment redistribution. Soil and runoff were sampled and analyzed to obtain nutrient variations. Results and discussion: Covered slope yielded less runoff and sediment in comparison to bare slope. Compared to bare slope, covered slope had lower total nitrogen (TN) (p = 4.8 × 10⁻²⁴) and total phosphorus (TP) (p = 2.9 × 10⁻²³) concentration but higher total organic carbon (TOC) concentration (p = 9.6 × 10⁻¹⁰). There was no significant difference between inorganic carbon (IC) concentrations on bare slope and covered slope (p = 0.051). Fractal dimensions ranged from 2.16 to 2.37 on bare slope, and they were greater than those from covered slope (ranged from 1.63 to 2.26). Linear and exponential relationships were established between fractal dimension and TOC, IC, TN, and TP concentrations. TOC concentration and IC concentration were in negative correlations with fractal dimension, while TN concentration and TP concentration were in positive correlations with fractal dimension. Mean elevation change analyzed from photogrammetry was − 4.9 and − 1.2 mm on bare slope and covered slope, respectively. Upslope sections were main elevation and nutrient loss areas. 9.8 mm soil lost on bare slope and 2.8 mm on covered slope. TOC, IC, and TP concentrations decreased on upper position, while TN increased. Three sections in middle area had dramatic erosion variations and decreased TOC. Elevation increased on covered slope in F3 section. On downslopes, IC content increased whereas TOC concentration increased. TN and TP content decreased in most sections on the bare slope, while the situation was changed on the filter covered slope, and TN and TP accumulated on the middle slope. Conclusions: Cover reduced runoff and sediment yield rates, and it also reduced elevation decrease degree. There was significant sediment deposition in the middle slope. Cover had functions in reducing TOC loss degree and preventing TN and TP loss out from the slope, but there was no significant difference between IC concentrations on bare slope and covered slope.

25877. 题目: Suction stress characteristics in granite red soils and their relationship with the collapsing gully in south China
文章编号: N18080707
期刊: CATENA
作者: Yusong Deng, Xiaoqian Duan, Shuwen Ding, Chongfa Cai, Jiazhou Chen
更新时间: 2018-08-07
摘要: The main goal of this research is to study the relationship between the soil suction stress and soil properties within four different soil profiles of collapsing gullies in the hilly granitic region of southern China. Large differences were found in the four soil layers between granite red soils, which are manifested in terms of soil bulk density, porosity, particle composition, clay minerals, micromorphology, organic matter, cation exchange capacity, permeability, oxide and hydraulics properties. The suction stress of the upper soils increases rapidly and almost linearly monotonously with the increase of matric suction, whereas C layers increases rapidly first, followed by a slow increase. The suction stress of the lower soils is significantly smaller than the upper soils under the same matric suction. These findings illustrate that the collapsing gully starts from the lower part of the granite red soil, and finally caused the gravity collapse in the upper soils, which is the main aspect that is different from the other types of soil erosion. Furthermore, suction stress has a very significant correlation with soil properties, with a positive correlation to the fine particle content, iron and aluminum oxide, and a negative correlation to coarse particles. In addition, suction stress can also be explained as being directly proportional to weathering degree. Our research provides a theoretical basis for the mass failures of the granite-derived red soil in southern China.

25878. 题目: Dissolved inorganic nitrogen fluxes from common Florida Bay (U.S.A.) sponges
文章编号: N18080706
期刊: Limnology and Oceanography
作者: Daniel R. Hoer, Jake P. Tommerdahl, Niels L. Lindquist, Christopher S. Martens
更新时间: 2018-08-07
摘要: Sponge biomass represents the largest heterotrophic component of benthic biota in the Florida Bay ecosystem. These organisms can significantly alter the water quality of their surrounding environment through biogeochemical transformations of nutrient elements resulting from their dynamic pumping, water filtration, and respiration processes. Ammonium (NH₄⁺) and nitrate plus nitrite (NO₃⁻ + NO₂⁻; NO _x⁻) fluxes were obtained for 11 ecologically important species at three sites within Florida Bay, Florida (U.S.A.) utilizing chamber incubations on undisturbed individual sponges. Significant dissolved inorganic nitrogen (DIN) effluxes ranging between 9.0 ± 2.2 μmol N h⁻¹ L_sponge⁻¹ and 141 ± 26 μmol N h⁻¹ L_sponge⁻¹ were observed for eight of the 11 tested sponges; specifically, from six of eight tested high‐microbial abundance (HMA) sponges, and from two of three tested low‐microbial abundance (LMA) sponges. The abundant HMA species Chondrilla nucula showed the highest, volume‐normalized rate of DIN release. These fluxes represent a continuation of the previously observed dichotomy in the chemical speciation of DIN in exhalent waters of LMA and HMA sponges, with NH₄⁺ and NO _x⁻ dominating their respective exhalent jets. Surprisingly, we found that dissolved organic matter (DOM) appeared to make a negligible contribution to the total released N, but we hypothesize that the lack of DOM utilization or production was due to methodological limitations. Our flux data combined with sponge biomass estimates indicate that sponges, particularly HMA species, are a large, and potentially dominant, source of inorganic nitrogen to Florida Bay waters.

25879. 题目: Combined effects of nitrogen fertilizer and straw application on aggregate distribution and aggregate‐associated organic carbon stability in an alkaline sandy loam soil
文章编号: N18080705
期刊: European Journal of Soil Science
作者: Z. Wang, Z. Wang, L. J. Ma, W. A. Khattak, W. Hu, Y. L. Meng, Z. G. Zhou
更新时间: 2018-08-07
摘要: Research on aggregate‐associated organic carbon (AOC) stability has increased, but its response to nitrogen (N) and straw (S) application after nitrogen reduction in alkaline sandy loam soil remains unclear. A two‐year field study and a short‐term incubation experiment were performed to investigate the combined effect of the N+S application on aggregate distribution and stability, and AOC content and mineralization in eastern China. The study involved three N amounts (75, 150 and 300 kg N ha^‐1) with or without straw amendments under continuous cotton–barley rotation. The N+S application promoted the formation of larger macroaggregates (8–2 mm), with larger mean weight diameter and geometric mean diameter than with N application alone. Aggregate stability increased significantly with increasing rate of N application. The amount of N had less effect on AOC content in the 0–20‐cm layer and cumulative mineralization of AOC in both layers compared to the N+S application. The addition of straw in promoting AOC, however, was more evident in the 20–40‐cm layer. Compared with N fertilizer alone, applying N+S increased the cumulative mineralization of AOC by 27.7 % in the 0–20‐cm layer and by 80.9 % in the 20–40‐cm layer for different rates of N and aggregate sizes. In addition, at 0–20‐cm depth, there was less C mineralization in macroaggregates than in microaggregates, indicating that macroaggregates showed better protection of AOC in that layer. Our study suggests that N application alone had a large effect on aggregate stability, whereas combined N+S application had a large effect on AOC content and its mineralization in the soil studied.

25880. 题目: Pollutant transport analysis and source apportionment of the entire non-point source pollution process in separate sewer systems
文章编号: N18080704
期刊: Chemosphere
作者: Yukun Ma, Shaonan Hao, Hongtao Zhao, Jinxiu Fang, Jiang Zhao, Xuyong Li
更新时间: 2018-08-07
摘要: Understanding pollutant transport process and source apportionment is critical to urban stormwater pollution mitigation. Previous studies have investigated transport and sources of road deposited sediments (RDS) and sewer sediments individually, and most of these studies focused on stormwater pollution in combined sewer systems. However, studies about pollutant transport and source apportionment of the entire urban non-point source pollution process in separate sewer systems are lacking. This study analyzed particle size distribution and chemical pollutants in five media during the entire pollutant process including RDS, roof runoff, road runoff, sewer sediments, and sewer runoff. The outcomes found that mass percentage of fine particles became greater during pollutant transport in stormwater runoff. According to transport characteristics, particles were grouped into three types: particles <20 μm, 20–105 μm, and >105 μm. Particles <20 μm had the highest mobility capacity and particles >105 μm had the lowest mobility capacity, while mobility capacity of particles 20–105 μm was uncertain. Pollutant concentrations in road runoff were significantly influenced by rainfall intensity and pollutant concentrations in sewer runoff could become lower during rainy seasons ignoring rainfall intensity. RDS was the main contributor of heavy metals while organic matter and nutrients were primarily contributed by sewer sediments. Roof runoff, road runoff and sewer sediments contributed 5.35%, 69.24% and 25.41% particles to urban receiving water, respectively. Based on the outcomes, several suggestions were given for stormwater management.
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