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28841. 题目: Environmental Conditions Affecting Re‐release from Particulate Matter of 4‐Nonylphenol into an Aqueous Medium
文章编号: N18121509
期刊: Environmental Toxicology and Chemistry
作者: Rebecca Lyons, Trevor Togashi, Chad Bowyer
更新时间: 2018-12-15
摘要: 4‐Nonylphenol (4‐NP) is a persistent organic pollutant with endocrine disrupting properties. This non‐polar product of microbial degradation derived from the surfactant nonylphenol polyethoxylate (NPE), 4‐NP is capable of long range transport attached to particulates. Bioactive concentrations of 4‐NP have been found in the surface water, soils, snow and particulate matter of the Eastern Sierra Nevada Mountains (SNM), hundreds of miles from its origins. As a result of particulate deposition, seasonal and glacial snow pack concentrations measured 20‐100 times higher than in surface waters. Batch desorption assays were run on particulate matter dosed with 4‐NP. Desorption was measured in 63‐500 μm particles under two different temperature conditions with varying fractions of organic carbon (OC) in turbulent or undisturbed states. Lower temperatures (4^°C) decreased the mean percentage of 4‐NP released from particulates in disturbed and undisturbed conditions, while the mean percentage of 4‐NP released at 20^°C was reduced by agitation; the effect of agitation at 4^°C was neither practically nor statistically significant. Particulates with higher percent OC (75%) released very little of the bound 4‐NP (0.53%) compared to particulates containing 4‐5% OC, which released up to 13%. Larger particles release the least amount of 4‐NP, while smaller particles released the most. Water and sediment samples taken from below the Palisades Glacier in the SNM showed the greatest 4‐NP concentrations directly below the glacier, implying that glacial particulates will release adsorbed 4‐NP. This article is protected by copyright. All rights reserved

28842. 题目: Changes in the pattern of polycyclic aromatic hydrocarbons in soil treated with biochar from a multiyear field experiment
文章编号: N18121508
期刊: Chemosphere
作者: Alessandro G. Rombolà, Daniele Fabbri, Silvia Baronti, Francesco Primo Vaccari, Lorenzo Genesio, Franco Miglietta
更新时间: 2018-12-15
摘要: The influence of biochar added to an agricultural soil on polycyclic aromatic hydrocarbon (PAH) levels, PAH diagnostic ratios and soil properties was investigated in a five-year field experiment. The experiment was carried out in an Italian vineyard and included two biochar treatments: 16.5 t ha⁻¹ of biochar applied in 2009 (soil B); 16.5 t ha⁻¹ in 2009 and further 16.5 t ha⁻¹ in 2010 (soil BB). A set of 75 samples that included five replicates and a control soil (untreated) was characterized in terms of organic carbon, pH, cation exchange capacity (CEC), bulk density and concentration of PAHs. Biochar addition to soil caused an increase in organic carbon, pH and CEC, and a decrease of bulk density. After almost two years the first application of biochar, PAH concentrations were higher in soil B (56 ng g⁻¹) and BB (153 ng g⁻¹) in comparison to control soil (24 ng g⁻¹). Thereafter, PAH concentrations decreased significantly, but the original PAHs levels were reached only in soil B after five years. The naphthalene/(naphthalene + phenanthrene) ratios were higher in the treated soils in accordance to the dominance of naphthalene in the original biochar. The cross plots naphthalene/(naphthalene + phenanthrene) vs. fluoranthene/(fluoranthene + pyrene) enabled to trace the signature of biochar PAHs up to five years after its first application. Diagnostic ratios can be a useful tool to study the persistence of PAHs introduced in soil by biochar when the pattern of these contaminants in biochar and original soil are different.

28843. 题目: Vertical profiles and distributions of aqueous endocrine-disrupting chemicals in different matrices from the Pearl River Delta and the influence of environmental factors
文章编号: N18121507
期刊: Environmental Pollution
作者: Jian Gong, Yong Ran, Dainan Zhang, Diyun Chen, Haiyan Li, Youda Huang
更新时间: 2018-12-15
摘要: The occurrence and distributions of selected endocrine-disrupting chemicals (EDCs), along with related environmental factors, were investigated in two rivers and six reservoirs in the Pearl River Delta. The vertical profiles of aqueous 4-tert-octylphenol (OP), 4-nonylphenol (NP), and estrone (E1) were constant, with little change in concentration between the surface and the river bottom, while higher aqueous concentrations of bisphenol A (BPA) were found in the bottom layers of the rivers. OP and NP in suspended particulate matter (SPM) were transferred from the surface to the bed layer, ultimately accumulating in the sediment. However, the particulate profiles of BPA and E1 both featured increases from the surface to the bottom layers and attenuation in the river bed. Dissolved oxygen (DO), water temperature, and pH were negatively correlated with the EDC concentrations, and negative relationships between DO and distribution coefficient (K_d) values for OP and NP were found as well. This indicated that these environmental parameters were primarily responsible for the EDC vertical distribution and SPM-water partitioning in the rivers. Positive relationships were observed between chlorophyll a and EDCs in the particulate phase, and the algae/water K_d values for EDCs in reservoirs were comparable to the SPM/water and sediment/water K_d values from the rivers. These results suggest that algae played an important role in regulating the distribution of EDCs in surface waters. Moreover, relationships between UV absorbance and EDCs revealed that π-π interactions were among the dissolved organic carbon (DOC)-EDC binding mechanisms and that DOC fractions with higher degrees of aromaticity and humification possessed higher affinities towards EDCs.
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28844. 题目: Assessment of forest fire impacts on carbonaceous aerosols using complementary molecular marker receptor models at two urban locations in California's San Joaquin Valley
文章编号: N18121506
期刊: Environmental Pollution
作者: Min-Suk Bae, Matthew J. Skiles, Alexandra M. Lai, Michael R. Olson, Benjamin de Foy, James J. Schauer
更新时间: 2018-12-15
摘要: Two hundred sixty-three fine particulate matter (PM_2.5) samples were collected over fourteen months in Fresno and Bakersfield, California. Samples were analyzed for organic carbon (OC), elemental carbon (EC), water soluble organic carbon (WSOC), and 160 organic molecular markers. Chemical Mass Balance (CMB) and Positive Matrix Factorization (PMF) source apportionment models were applied to the results in order to understand monthly and seasonal source contributions to PM_2.5 OC. Similar source categories were found from the results of the CMB and PMF models to PM_2.5 OC across the sites. Six source categories with reasonably stable profiles, including biomass burning, mobile, food cooking, two different secondary organic aerosols (SOAs) (i.e., winter and summer), and forest fires were investigated. Both the CMB and the PMF models showed a strong seasonality in contributions of some sources, as well as dependence on wind transport for both sites. The overall relative source contributions to OC were 24% CMB wood smoke, 19% CMB mobile sources, 5% PMF food cooking, 2% CMB vegetative detritus, 17% PMF SOA summer, 22% PMF SOA winter, and 12% PMF forest fire. Back-trajectories using the Weather Research and Forecasting model combined with the FLEXible PARTicle dispersion model (WRF-FLEXPART) were used to further characterize wind transport. Clustering of the trajectories revealed dominant wind patterns associated with varying concentrations of the different source categories. The Comprehensive Air Quality Model with eXtensions (CAMx) was used to simulate aerosol transport from forest fires and thus confirm the impacts of individual fires, such as the Rough Fire, at the measurement sites.
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28845. 题目: Electrochemical characterization of mangrove sediments: A proposal of new proxies for organic matter oxidation
文章编号: N18121505
期刊: Applied Geochemistry
作者: Gerardo Cebrián-Torrejón, Alexander Pérez, Noemí Montoya, Joan Piquero-Cilla, Maritza S. Saldarriaga, Dimitri Gutiérrez, Christian J. Sanders, Wilson Machado, Antonio Doménech-Carbó
更新时间: 2018-12-15
摘要: The voltammetric response of microparticulate deposits resulting from solvent evaporation of ethanolic extracts of mangrove sediments in contact with aqueous acetate buffer is hereby described. Dated sediment cores sampled from the Peruvian mangrove system (“Manglares de Tumbes” National Sanctuary) presented voltammetric responses dominated by oxidative signals of organic components that exhibit significant variations depending on the depth. Voltammetric data allowed for the definition of electrochemical indexes representative of the electrochemically oxidable organic matter fraction. These electrochemical indexes were f_EAOM (for the total amount of organic matter being electrochemically active), f_EROM (for the fraction of organic matter electrochemically oxidizable in reversible form), f_RDOX (for the proportion between the fractions of electrochemically active organic matter which is in an oxidized state and in a reduced state) and f_ROS (capability for reaction with reactive oxygen species), while the spectroscopic index A₁₆₅₀/A₃₄₀₀ (as a proxy analogous to f_RDOX) was also applied. The mangrove forest presents a higher oxidized fraction of the electrochemically active organic matter, as confirmed by additional data obtained from infrared spectroscopy. These results indicate that the described electrochemical indexes may provide insights on organic matter degradation by oxidative processes in addition to chemical analyses of coastal vegetated systems that are currently used, such as mangrove wetlands.

28846. 题目: Using a combination of PLFA and DNA-based sequencing analyses to detect shifts in the soil microbial community composition after a simulated spring precipitation in a semi-arid grassland in China
文章编号: N18121504
期刊: Science of The Total Environment
作者: Hao Chen, Xiaorong Zhao, Qimei Lin, Guitong Li, Weidong Kong
更新时间: 2018-12-15
摘要: Increased spring precipitation in semi-arid grasslands could improve annual primary productivity. However, little is known about the responses of soil microbes to individual spring precipitation. In this study, we combined phospholipid fatty acid (PLFA) and DNA-based high-throughput sequencing analyses to investigate short-term (days) shifts in the soil microbial community composition after a simulated spring precipitation. Under field conditions, the soils (approx. −0.3 MPa) were exposed to either a watering of 20 cm or natural drought, and soil samples were collected at days 1, 3, 5, 8, and 12 after watering. Soil labile organic carbon (C) and nitrogen (N) as well as microbial biomass C (MBC) were positively correlated with soil water content (SWC). Spring watering significantly increased plant phosphorus (P) uptake, but had no impact on soil available P (AP). Watering increased the PLFA biomarkers indicative for Gram-negative (G⁻) bacteria and fungi. Two phyla of G⁻ bacteria, Proteobacteria and Bacteroidetes, as well as the fungal phylum Ascomycota were more abundant when SWC increased. In addition to SWC and its related environmental factors such as C and N availabilities, AP appeared to be an important factor in shaping the soil microbial community composition. The study highlights the combination use of the methods based on different microbial biomarkers (PLFA vs. DNA), and the results were in line with each other. While the PLFA-based method was more sensitive to short-term shifts in soil microbial community composition in response to a precipitation event, DNA-based method could provide more information on the microbial taxa at a finer taxonomic resolution. Our results provide methodological insights for future research on short-term response of soil microbial community to changing environmental conditions.
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28847. 题目: The role of check dams in retaining organic carbon and nutrients. A study case in the Sierra de Ávila mountain range (Central Spain)
文章编号: N18121503
期刊: Science of The Total Environment
作者: J. Mongil-Manso, V. Díaz-Gutiérrez, J. Navarro-Hevia, M. Espina, L. San Segundo
更新时间: 2018-12-15
摘要: Soil organic carbon plays an important role in the global carbon cycle, accounting for 70% of the Earth's carbon. However, soil erosion can have a major impact on the stocks of soil carbon and other soil nutrients, such as nitrogen and phosphorous. Soil and water conservation techniques, such as the building of check dams, are usually employed to control sediment yields and the losses of other soil components. The aim of this research is thus to quantify the soil organic carbon (SOC), soil nitrogen (SN) and soil phosphorous (SP) retained by the check dams of a hydrologic and forest restoration project in the Sierra de Ávila mountain range (Ávila, Central Spain). Soil samples were taken from the sediment wedges of 30 check dams and from 30 native soils. Soil texture, electric conductivity, pH, C, N and P were measured in all the soil samples. The volume of sediment retained by the check dams was calculated by the Sections Method, which is very accurate in estimating the real volume of the sediment wedges. The total sediment yield in the area was thus estimated at 6.40 Mg·ha⁻¹·yr⁻¹ and the mean SOC, SN and SP densities were respectively 13.76, 0.48 and 0.05 kg·m⁻². These findings thus are very reliable and allow us to conclude that check dams constitute an important instrument for controlling losses of SOC, SN and SP, and preventing these substances from passing into watercourses downstream of the area.
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28848. 题目: Susceptibility of soil organic carbon to priming after long-term CO₂ fumigation is mediated by soil texture
文章编号: N18121502
期刊: Science of The Total Environment
作者: Qiao Xu, Jian Jin, Xiaojuan Wang, Roger Armstrong, Caixian Tang
更新时间: 2018-12-15
摘要: Elevated CO₂ (eCO₂) may enhance soil organic carbon (SOC) sequestration via greater input of photosynthetic carbon (C). However, greater rhizodeposits under eCO₂ may stimulate microbial decomposition of native SOC. This study aimed to examine the status and stability of SOC in three Australian cropping soils after long-term CO₂ enrichment. Samples (0–5 cm) of Chromosol, Vertosol and Calcarosol soils were collected from an 8-year Free-air CO₂ Enrichment (SoilFACE) experiment and were used to examine SOC dynamics by physical fractionation and incubation with ¹³C-glucose. Compared to the ambient CO₂ (aCO₂) (390–400 μmol mol⁻¹), 8 years of elevated CO₂ (eCO₂) (550 μmol mol⁻¹) did not increase SOC concentration of all soils, but changed SOC distribution with 12% more C in coarse soil fractions and 5% less C in fine fractions. Elevated CO₂ also enhanced the susceptibility of SOC to ¹³C-glucose-induced priming, but this effect was only significant in the coarse-textured Calcarosol topsoil. The eCO₂ history increased labile C (coarse C fraction, +13%) and soil pH (+0.25 units), and decreased available N (−30%) in the Calcarosol, which stimulated microbial biomass C by 28%, leading to an enhanced priming effect. Despite with greater total primed C, the Chromosol that had the highest amount of native C, had lower primed C per unit of SOC when compared to the low-C Calcarosol. In conclusion, the effect of long-term eCO₂ enrichment on soil C and N availability in cropping soils depended on soil type with the coarse-textured Calcarosol soil being more susceptible to substrate-induced decomposition of its SOC.
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28849. 题目: Optical and molecular signatures of dissolved organic matter in Xiangxi Bay and mainstream of Three Gorges Reservoir, China: Spatial variations and environmental implications
文章编号: N18121501
期刊: Science of The Total Environment
作者: Kai Wang, Yu Pang, Chen He, Penghui Li, Shangbin Xiao, Yongge Sun, Qiong Pan, Yahe Zhang, Quan Shi, Ding He
更新时间: 2018-12-15
摘要: With the on-going boom in the construction of dam reservoirs all over the world, the sources and composition of dissolved organic matter (DOM) in fluvial networks are expected to be altered. Considering the importance of DOM as a key biogeochemical component in inland waters, this might bring important ecological and environmental influences. However, limited information is available on the molecular composition of DOM in dam reservoirs. In this study, the spatial characteristics of DOM composition were investigated in Xiangxi tributary and mainstream of the Three Gorges Reservoir (TGR), the largest freshwater reservoir in the world. The concentration alteration of conservative cations revealed the water intrusion from mainstream into Xiangxi tributary, which mainly controlled the hydrological gradient. One tyrosine-like (C4), one tryptophan-like (C2), and two humic-like (C1 and C3) fluorescent components were identified in fluorescent DOM (FDOM) by parallel factor analysis (PAFACAC), potentially indicating algal, anthropogenic, and terrestrial inputs, respectively. Decreasing trends of C1, C3 and C4 components and an increasing trend of C2 component were observed from Xiangxi tributary to mainstream, indicating higher terrestrial and algal inputs but lower anthropogenic inputs in Xiangxi tributary compared to mainstream. The Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) characterization further revealed substantial heterogeneity of DOM at the molecular level. Interestingly, S-containing compounds related to synthetic surfactants were consistently detected, and their relative abundances showed an increasing trend from Xiangxi tributary to mainstream, in agreement with the distribution of the anthropogenic derived C2 component. Meanwhile, numerous lignin-like S-containing compounds were identified, likely the result of the incorporation of sulfide ions to lignin-like CHO compounds. This study represents the first molecular level characterization of DOM in the TGR system, which should aid the design and implementation of more detailed future studies.
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28850. 题目: Spatial and temporal heterogeneity in the structure and function of sediment bacterial communities of a tropical mangrove forest
文章编号: N18121413
期刊: Environmental Science and Pollution Research
作者: Pratiksha Behera, Madhusmita Mohapatra, Ji Yoon Kim, Tapan K. Adhya, Ajit K. Pattnaik, Gurdeep Rastogi
更新时间: 2018-12-14
摘要: Bacterial communities of mangrove sediments are well appreciated for their role in nutrient cycling. However, spatiotemporal variability in these communities over large geographical scale remains understudied. We investigated sediment bacterial communities and their metabolic potential in an intertidal mangrove forest of India, Bhitarkanika, using high-throughput sequencing of 16S rRNA genes and community-level physiological profiling. Bulk surface sediments from five different locations representing riverine and bay sites were collected over three seasons. Seasonality largely explained the variation in the structural and metabolic patterns of the sediment bacterial communities. Freshwater Actinobacteria were more abundant in monsoon, whereas γ-Proteobacteria demonstrated higher abundance in summer. Distinct differences in the bacterial community composition were noted between riverine and bay sites. For example, salt-loving marine bacteria affiliated to Oceanospirillales were more prominent in the bay sites than the riverine sites. l-asparagine, N-acetyl-d-glucosamine, and d-mannitol were the preferentially utilized carbon sources by bacterial communities. Bacterial community composition was largely governed by salinity and organic carbon content of the sediments. Modeling analysis revealed that the abundance of δ-Proteobacteria increased with salinity, whereas β-Proteobacteria displayed an opposite trend. Metabolic mapping of taxonomic data predicted biogeochemical functions such as xylan and chitin degradation, ammonia oxidation, nitrite reduction, and sulfate reduction in the bacterial communities suggesting their role in carbon, nitrogen, and sulfur cycling in mangrove sediments. This study has provided valuable clues about spatiotemporal heterogeneity in the structural and metabolic patterns of bacterial communities and their environmental determinants in a tropical mangrove forest.

28851. 题目: Mechanistic Study on the Role of Soluble Microbial Products in Sulfate Radical-Mediated Degradation of Pharmaceuticals
文章编号: N18121412
期刊: Environmental Science & Technology
作者: Lingwei Gao, Daisuke Minakata, Zongsu Wei, Richard Spinney, Dionysios D. Dionysiou, Chong-Jian Tang, Liyuan Chai, Ruiyang Xiao
更新时间: 2018-12-14
摘要: The role of soluble microbial products (SMP), the most important component of effluent organic matter from municipal wastewater treatment plants, in sulfate radical (SO₄^•–)-based advanced oxidation technologies (AOTs) remains substantially unclear. In this study, we first utilized a suite of macro- and microanalytical techniques to characterize the SMP from a membrane bioreactor for its fundamental molecular, spectroscopic, and reactivity properties. The degradation kinetics of three representative pharmaceuticals (i.e., naproxen, gemfibrozil, and sulfadiazine) in the presence of SMP was significantly reduced as compared to in its absence. Possible mechanisms for the interference by SMP in degrading these target compounds (TCs) were investigated. The low percentage of bound TCs to SMP ruled out the cage effect. The measurement of steady-state ¹O₂ concentration indicated that formation of ¹O₂ upon UV irradiation on SMP was not primarily responsible for the degradation of TCs. However, the comparative and quenching results reveal that SMP absorbs UV light acting as an inner filter toward the TCs, and meanwhile scavenges SO₄^•– with a high second-order rate constant of 2.48 × 10⁸ M_C^–1 s^–1.
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28852. 题目: Influence of alkaline silicon-based amendment and incorporated with biochar on the growth and heavy metal translocation and accumulation of vetiver grass ( Vetiveria zizanioides ) grown in multi-metal-contaminated soils
文章编号: N18121411
期刊: Journal of Soils and Sediments
作者: Jing Mu, Zhengyi Hu, Lijuan Huang, Sichen Tang, Peter E. Holm
更新时间: 2018-12-14
摘要: Purpose: This study investigated the effects of alkaline silicon-based amendment (A) and incorporated with biochar (B) on the growth, heavy metal translocation, and accumulation of vetiver grass (Vetiveria zizanioides) grown in multi-metal-contaminated soils. Materials and methods: Soil incubation for 6 months and pot experiments for 6 months were performed to investigate the growth and the translocation factor (TF) and bioaccumulation factor (BCF) values of heavy metals in vetiver grown in As-, Cd-, Cr-, and Pb-contaminated soils amended with A (0.5%) and AB (0.5% A; 1.5% B). Results and discussion: The vetiver could grow in multi-metal-contaminated soils due to the restriction of metals translocation in vetiver. Vetiver could be the plant for phytostabilization of As, Cr, Cd, and Pb because As, Cr, Cd, and Pb accumulated by the vetiver were largely retained in the roots, as the TF values for As, Cr, Cd, and Pb were < 1; the BCF values for As, Cr, Cd, and Pb were obviously greater in roots than shoots. Application of A and AB markedly improved vetiver growth due to A- and AB-induced accumulation of Cd, Pb, and Cr in the roots, and then enhanced phytostabilization of Cd, Pb, and Cr in roots based on the BCF values, and the immobilization of Cd and Pb in soils based on increase of soil pH and Si-induced accumulation of Cd, Pb, and Cr in the roots. Conclusions: Vetiver represents a candidate for revegetation of multi-metal-contaminated soils amended by A or AB. Further investigations are required to determine the feasibility of revegetation in multi-metal-contaminated soils at the field scale.

28853. 题目: Exchanges of nitrogen and phosphorus across the sediment-water interface influenced by the external suspended particulate matter and the residual matter after dredging
文章编号: N18121410
期刊: Environmental Pollution
作者: Cheng Liu, Yiheng Du, Hongbin Yin, Chengxin Fan, Kaining Chen, Jicheng Zhong, Xiaozhi Gu
更新时间: 2018-12-14
摘要: Dredging is frequently implemented for the reduction of internal nitrogen (N) and phosphorus (P) loadings and the control of eutrophication. Residuals during dredging activities and external pollution loadings after dredging both commonly contribute to influence the effectiveness of dredging and have been widely discussed. In the current study, the exchanges of N and P across the sediment-water interface (SWI) to these two factors were compared in a six-month field incubation experiment. The results showed that the continuous deposition of external suspended particulate matter (SPM) led ammonium nitrogen (NH₄⁺N) and soluble reactive phosphorus (SRP) fluxes across the newly formed SWI to increase by factors of 4.16 and 12.71, respectively, while residual material caused the same fluxes to increase by factors of 2.06 and 5.06. Both the deposition of external SPM and the residual matter led to higher increase of the fluxes of P across the SWI than those of the fluxes of N across the SWI after dredging. The SPM easily adsorbed P in the water due to extensive adsorption of water soluble organic matter (consisting primarily of easily-decomposed humic-like substances), iron, and aluminum. However, the decomposition of organic matter in the SPM after the deposition on the dredged sediment accelerated the dissolution of redox-sensitive P and organic P across the SWI after dredging. Both the increase in the fluxes of N and P across the SWI would further increase the concentrations of N and P in the overlying water and thereby aggravate the eutrophication status in lakes. More frequent dredging operations might be necessary to reduce the fluxes of N and P from the sediment due to the continuous influence of the external SPM and the residual matter.
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28854. 题目: Effects of forest fragmentation on organic carbon pool densities in the Mongolian forest-steppe
文章编号: N18121409
期刊: Forest Ecology and Management
作者: Choimaa Dulamsuren, Michael Klinge, Banzragch Bat-Enerel, Tumurbaatar Ariunbaatar, Daramragchaa Tuya
更新时间: 2018-12-14
摘要: The hypothesis was tested that the size and the degree of isolation of Larix sibirica forests in the forest-steppe ecotone of Mongolia affects aboveground and belowground carbon pool densities. The research question was based on the fact that both microclimate and the drought sensitivity of stemwood production were earlier shown to differ with stand size and isolation in this ecotone. Contrary to our hypothesis, we did not find significant differences in the organic carbon stock densities of the tree biomass and the mineral soil. The depth, carbon content and carbon stock density of the organic layer increased with stand size, but was not a major determinant of total ecosystem carbon stock density. Nevertheless, the increasing depth and the increasing humus content of the organic layer with stand size could be significant by improving moisture availability and, thus, promoting forest regeneration. Furthermore, reduced organic layer thickness and humus content and thus water storage capacity could be one out of several causes of the previously observed higher drought vulnerability of stemwood formation in small forest stands of the Mongolian forest-steppe. A mean carbon stock density of 237 Mg C ha⁻¹ for total ecosystem organic carbon stock density matches with earlier estimates for Mongolia’s boreal forest corroborating the view that the ecosystem carbon pool density at the southern edge of the boreal forest is lower compared to forests at higher latitudes with even colder climate and deeper and more widespread permafrost.

28855. 题目: Changes in soil hydraulic conductivity after prescribed fires in Mediterranean pine forests
文章编号: N18121408
期刊: Journal of Environmental Management
作者: P.A. Plaza-Álvarez, M.E. Lucas-Borja, J. Sagra, D.A. Zema, J. González-Romero, D. Moya, J. De las Heras
更新时间: 2018-12-14
摘要: Prescribed fire removes or reduces the plant material that is prone to forest fires by creating fuel discontinuity and minimising fire intensity. This forest management tool potentially impacts Mediterranean ecosystems hydrological response by influencing water infiltration into soil. As direct measurements (e.g. by infiltrometers) of unsaturated infiltration in soil subjected to prescribed fires are scarce, this study has evaluated changes in soil hydraulic conductivity (SHC) using Minidisk infiltrometer after prescribed fires in representative plots of forests in the Iberian Peninsula under Mediterranean semi-arid conditions: (i) pure forest of Black pine Arnold ssp salzmannii; (ii) mixed forest of Maritime and Black pine; (iii) mixed forest of Aleppo and Maritime pine. The results have shown that fire reduced the organic layer thickness and its organic matter content. Consequently, after the prescribed fire the water content of burned plots was always lower than in untreated soils; conversely, the reverse soil behaviour was noticed before applying fire. Compared to the untreated soils, and with very few exceptions, prescribed fire did not cause significant changes in SHC. No general patterns in the comparisons between treatments (burned/unburned soils), in time evolution after fires and in the interactions between these effects were detected. This means that the SHC of burned soils followed the temporal variations of untreated soils. The lack of significance of these differences between treatments could be due to the low-fire severity and the limited effect of temperature in the mineral layer on soil hydraulic properties. This effect was expected and agrees with other studies. Overall prescribed fires did not alter SHC in Mediterranean forest ecosystems under unsaturated conditions since fire was of low-severity.

28856. 题目: A simple pipeline for the assessment of legacy soil datasets: An example and test with soil organic carbon from a highly variable area
文章编号: N18121407
期刊: CATENA
作者: Calogero Schillaci, Marco Acutis, Fosco Vesely, Sergio Saia
更新时间: 2018-12-14
摘要: Legacy databases provide unique information on soil properties and act as a guide for the setup of monitoring processes. However, their use requires an evaluation of their drawbacks, especially when aiming to model the soil traits by depth. We set up a procedure for the integration and error correction of a soil legacy database. This database consisted of 6994 records in its original form and 6674 records after correction. These records were collected from 2886 locations in the south of Italy on a 25,711-km² island (Sicily, Italy). Samples were taken in arable lands (5471 records), orchards, vineyards and seminatural lands (3010 records), and woodland and natural areas (1203 records). The procedure for the integration and error highlighting improved the prediction of soil organic carbon (SOC), and a general linear model with covariate selection by Least Absolute Shrinkage and Selection Operator (LASSO) tested the procedure. We focussed on exploring the amount of legacy information as georeferenced soil properties. SOC and fine earth fractions were analysed for each sample. Bulk density was provided for only 20% of the samples. These results will help to account for the legacy data available and propose an analysis to harmonize an SOC dataset; highlight missing or incorrect data; summarize data; and offer synthesis criteria for benchmarking SOC in different land uses and pedological areas. In addition, the results may stimulate funding bodies to support research in an open data frame, which can be turned into more sustainable use of resources, improved communication between governments and farmers, and the production of standard datasets that meet and facilitate the requirements for regional agro-environmental modelling.

28857. 题目: Co-treatment of potassium ferrate and ultrasonication enhances degradability and dewaterability of waste activated sludge
文章编号: N18121406
期刊: Chemical Engineering Journal
作者: Wei Li, Najiaowa Yu, Anran Fang, Bingfeng Liu, Nanqi Ren, Defeng Xing
更新时间: 2018-12-14
摘要: The enhancement of the degradability and dewaterability of waste activated sludge (WAS) is important scientific and engineering topics because sludge treatment has strict environmental regulations due to increased urbanization. The impact of three co-treatments (alkali combined with ultrasonication, potassium ferrate (K₂FeO₄) combined with ultrasonication, and potassium ferrate combined with alkali) on the degradability and dewaterability of sewage sludge and the nutrient release during the co-treatment was investigated. The soluble chemical oxygen demand (SCOD) and disintegration degree (DD_SCOD) increased sharply after the co-treatment and the increase in the DD_SCOD was almost 40% for the potassium ferrate combined with an ultrasonication treatment after 90 min. The decreased dewaterability observed for the alkaline and potassium ferrate pretreatments was further lowered when combined with ultrasonication based on the increase in the capillary suction time (CST) from 26.4±1.8 s to 1614.1±131 s. The ultrasonication treatment produced a high proportion of colloidal solids (d (0.9) = 6.492) and eluted soluble extracellular polymeric substances (EPS), which are detrimental to the filterability of the WAS. Fe (III) was highly flocculated in the solution and re-coagulated the small particles formed during the ultrasonic crushing process. The evidences regarding the soluble EPS, total organic carbon, total nitrogen, total phosphorus, and volatile suspended solids indicated that the co-treatment of potassium ferrate and ultrasonication was effective for disintegrating WAS, and provided a new way for WAS pretreatment.
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28858. 题目: Production of polyhydroxyalkanoates by activated sludge: correlation with extracellular polymeric substances and characteristics of activated sludge
文章编号: N18121405
期刊: Chemical Engineering Journal
作者: Heng Li, Jinfeng Zhang, Liang Shen, Zheng Chen, Yanan Zhang, Chuanpan Zhang, Qingbiao Li, Yuanpeng Wang
更新时间: 2018-12-14
摘要: To understand PHAs accumulation process well in the stand point of the sludge characteristics, polyhydroxyalkanoates (PHAs) accumulation by activated sludge was investigated in correlation with sludge properties, such as particle size, mixed liquor suspended solids (MLSS) and extracellular polymeric substances (EPS) under different carbon sources (e.g., acetate, propionate and mixed carbons) at 2, 4, 6 and 8 g/L. The efficiency of PHAs synthesis from sludge with sodium acetate as carbon source was superior to that with sodium propionate as carbon source and mixed carbon sources in the sequencing biological reactors, while EPS and sludge characteristics showed similar trends for each carbon source. Various carbon sources did not induce significant differences in the correlations. Polyhydroxybutyrate (PHB) showed good correlation with MLSS (R= 0.782) and sludge floc size (R=-0.58). In the reactors with carbon sources of propionate and mixed carbons, polyhydroxyvalerate (PHV) and PHBV correlated with MLSS (R=0.480 and 0.489, respectively), sludge floc size (R=-0.921 and -0.666, respectively) and concentrations of polysaccharides (R=0.726, 0.557, respectively). According to the correlations, improving the concentration of sludge, promoting the production of extracellular polymeric substances (EPS) and decreasing the sludge floc size were supposed to be effective approaches for further accumulation of the PHAs. This study is the first to systematically establish the correlations among EPS, characteristics of activated sludge and PHAs accumulation, can provide a theoretical foundation for the engineering design and the operational parameters selection of PHAs production by activated sludge.
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28859. 题目: The concentration of dissolved organic matter impacts the metabolic response in Daphnia magna exposed to 17α-ethynylestradiol and perfluorooctane sulfonate
文章编号: N18121404
期刊: Ecotoxicology and Environmental Safety
作者: Vera Kovacevic, André J. Simpson, Myrna J. Simpson
更新时间: 2018-12-14
摘要: The pharmaceutical 17α-ethynylestradiol (EE2) and the industrial chemical perfluorooctane sulfonate (PFOS) are organic contaminants frequently detected in freshwater environments. It is hypothesized that hydrophobic organic contaminants can sorb to dissolved organic matter (DOM) and this may reduce the toxicity of these contaminants by reducing the contaminants’ bioavailability. To investigate this hypothesis, ¹H nuclear magnetic resonance (NMR)-based metabolomics was used to determine how the metabolome of Daphnia magna changes when a range of DOM concentrations are added during EE2 and PFOS exposure experiments. D. magna were exposed for 48 h to sub-lethal concentrations of 1 mg/L EE2 or 30 mg/L PFOS in the presence of 0, 1, 2, 3 and 4 mg dissolved organic carbon (DOC)/L. EE2 exposure resulted in increased amino acids and decreased glucose in D. magna. All DOM concentrations were able to lessen these metabolite disturbances from EE2 exposure, likely due to reductions in the bioavailability of EE2 through interactions with DOM. Exposure to PFOS resulted in decreased amino acids, and the presence of 1 mg DOC/L did not alter this metabolic response. However, PFOS exposure with the higher DOM concentrations resulted in a different pattern of metabolite changes which may be due to combined impacts of PFOS and DOM on the metabolome or due to an increase in PFOS bioavailability and uptake in D. magna. These results suggest that the concentration of DOM influences the sensitive biochemical changes in organisms that occur during acute sub-lethal exposure to organic contaminants.
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28860. 题目: Improving agricultural water use efficiency with biochar – A synthesis of biochar effects on water storage and fluxes across scales
文章编号: N18121403
期刊: Science of The Total Environment
作者: Benjamin M.C. Fischer, Stefano Manzoni, Laura Morillas, Monica Garcia, Mark S. Johnson, Steve W. Lyon
更新时间: 2018-12-14
摘要: There is an urgent need to develop agricultural methods that balance water supply and demand while at the same time improve resilience to climate variability. A promising instrument to address this need is biochar – a charcoal made from pyrolyzed organic material. However, it is often unclear how, if at all, biochar improves soil water availability, plant water consumption rates and crop yields. To address this question, we synthesized literature-derived observational data and evaluated the effects of biochar on evapotranspiration using a minimal soil water balance model. Results from the model were interpreted in the Budyko framework to assess how climatic conditions mediate the impacts of biochar on water fluxes. Our analysis of literature-derived observational data showed that while biochar addition generally increases the soil water holding capacity, it can have variable impacts on soil water retention relative to control conditions. Our modelling demonstrated that biochar increases long-term evapotranspiration rates, and therefore plant water availability, by increasing soil water retention capacity – especially in water-limited regions. Biochar amendments generally increased crop yields (75% of the compiled studies) and, in several cases (35% of the compiled studies), biochar amendments simultaneously increased crop yield and water use efficiencies. Hence, while biochar amendments are promising, the potential for variable impact highlights the need for targeted research on how biochar affects the soil-plant-water cycle.
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