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13941. 题目: Soil N/P and C/P ratio regulate the responses of soil microbial community composition and enzyme activities in a long-term nitrogen loaded Chinese fir forest
文章编号: N18122610
期刊: Plant and Soil
作者: Fangfang Shen, Jianping Wu, Houbao Fan, Wenfei Liu, Xiaomin Guo, Honglang Duan, Liang Hu, Xueming Lei, Xiaohua Wei
更新时间: 2018-12-26
摘要: Aims: Long-term nitrogen (N) fertilization has been shown to profoundly affect the soil microorganisms and strongly result in several imbalances in element concentrations. The objective of this study was to examine links among the soil microorganisms, enzyme activities, and soil carbon (C), N, and phosphorus (P) stoichiometry in a subtropical Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) plantation after continuous N fertilization for 13 years. Methods: This study was performed in 25-year-old fir plantation along a fertilization gradient (0, 60, 120, and 240 kg N ha−1 yr.−1), designated as N0, N1, N2, and N3, respectively. Soil microbial properties, including the microbial community composition, as revealed by phospholipid fatty acids (PLFAs), and soil enzyme activities (i.e., sucrase, urease and catalase) were measured, and soil elemental stoichiometry was calculated based on soil C, N, and P concentrations. A redundancy analysis (RDA) was conducted to determine the relationship between soil C:N:P stoichiometry and soil microbial properties. Results: Compared with the control (N0), N fertilization decreased the total PLFAs (−12.20%), bacteria (−14.33%), fungi (−12.97%), and actinomycetes (−17.11%) on average. Sucrase, urease and catalase activities were enhanced by low and middle levels of N (N1 and N2), but not with high level of N (N3). Long-term N fertilization decreased soil pH, C to N ratio (C/N), and C to P ratio (C/P), while increased soil C, N and N to P ratio (N/P). The RDA identified the first two axes of soil stoichiometry variation that explained 20.4% of the variation at the soil depth of 0–20 cm, 28.6% at 20–40 cm and 49.9% at 40–60 cm in PLFAs biomarkers and enzymes, respectively. Significant correlations between soil stoichiometry (soil N/P and C/P ratio) and soil microbial properties were found in this study. Conclusions: These observations suggested that long-term N fertilization influenced soil microbial community composition and enzyme activities by changing the soil C/P and N/P ratios. Future studies are needed to consider the coupling relationships between soil microbial community composition, enzyme activities and elemental stoichiometry in different ecosystems under future climatic change.

13942. 题目: Characterization of changes in extracellular polymeric substances and heavy metal speciation of waste activated sludge during typical oxidation solubilization processes
文章编号: N18122609
期刊: Journal of Environmental Sciences
作者: Qiongying Xu, Huidi Wang, Qiandi Wang, Weijun Zhang, Dongsheng Wang
更新时间: 2018-12-26
摘要: Biopolymer solubilization is considered to be the rate-limiting stage of anaerobic digestion of waste activated sludge (WAS). Oxidation processes have been proven to be effective in disrupting sludge flocs and causing solubilization of the solid biopolymers. In this study, WAS was treated by NaNO2 or H2O2 oxidation at pH of 2. The changes in extracellular polymeric substances properties and the speciation of heavy metals were investigated. The results revealed that both NaNO2 and H2O2 treatments were effective in solubilizing organics in WAS, while the conversion of biopolymers in the two treatment processes was different. Free nitrous acid destroyed the gel network structure of EPS, and organic materials were released from the solid phase to the supernatant. Indigenous peroxidase catalyzed H2O2 to produce hydroxyl radicals which caused significant solubilization of biopolymers, and the protein-like substances were further degraded into micro-molecule polypeptides or amino acids at high dosages of H2O2. During the oxidation processes, Zn, Cd and Cu, with excellent mobility, tended to migrate to the supernatant, and thus were easy to remove through the liquid–solid separation process. Ni and As showed moderate migration ability, of which the residual fraction tended to transform into reducible and soluble fractions. With poor mobility, Cr and Pb mainly existed in the forms of residual and oxidizable fractions, which were difficult to dissolve and remove from WAS. Both NaNO2 and H2O2 treatment resulted in the enhancement of sludge solubilization efficiency and heavy metal mobility in WAS, but different heavy metals showed distinct migration and transformation behaviors.
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13943. 题目: Microbial response to CaCO3 application in an acid soil in southern China
文章编号: N18122608
期刊: Journal of Environmental Sciences
作者: Anning Guo, Longjun Ding, Zhong Tang, Zhongqiu Zhao, Guilan Duan
更新时间: 2018-12-26
摘要: Calcium carbonate (CaCO3) application is widely used to ameliorate soil acidification. To counteract soil and bacterial community response to CaCO3 application in an acidic paddy soil in southern China, a field experiment was conducted with four different dosages of CaCO3 addition, 0, 2.25, 4.5 and 7.5 tons/ha, respectively. After one seasonal growth of rice, soil physicochemical properties, soil respiration and bacterial communities were investigated. Results showed that soil pH increased accordingly with increasing dose of CaCO3 addition, and 7.5 tons/ha addition increased soil pH to neutral condition. Moderate dose of CaCO3 application (4.5 tons/ha) significantly increased soil dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) content, enhanced soil respiration, while the excessive CaCO3 application (7.5 tons/ha) decreased these soil properties. High-throughput sequencing results illustrated that moderate dose of CaCO3 application increased the richness and alpha diversity of soil bacterial community. Compared with control, the relative abundance of Anaerolineaceae family belonging to Chloroflexi phylum increased by 38.7%, 35.4% and 24.5% under 2.25, 4.5 and 7.5 tons/ha treatments, respectively. Redundancy analysis (RDA) showed that soil pH was the most important factor shaping soil bacterial community. The results of this study suggest that proper dose of CaCO3 additions to acid paddy soil in southern China could have positive effects on soil properties and bacterial community.
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13944. 题目: Urbanization altered regional soil organic matter quantity and quality: Insight from excitation emission matrix (EEM) and parallel factor analysis (PARAFAC)
文章编号: N18122607
期刊: Chemosphere
作者: Liwei Chai, Muke Huang, Hao Fan, Jie Wang, Dalin Jiang, Mengjun Zhang, Yi Huang
更新时间: 2018-12-26
摘要: Soil organic matter (SOM) play an important role in soil ecology and global carbon dynamic. As one of the most sever and irreversible land use change, urbanization could alter the regional carbon storage and composition pattern. However how urbanization influence on SOM is still unclear. In this study, we collected soil samples from highly urbanized area of Beijing, China and explore the quantity and quality variations of SOM by using fluorescence spectroscopy in combine with parallel factor analysis (PARAFAC). The results shown that the soil physic-chemical properties were shaped by urbanization. Comparing to nature soil, moisture content, total organic carbon and total nitrogen in urban and rural soil significantly decreased. The fluorescence spectrum demonstrated that SOM quality was also altered by urbanization induced environmental changes. Five fluorescent compounds in SOM was identified by PARAFAC model and three of them was assigned to humic-like substances. The fluorescence intensity of humic-like substances in nature land was significantly higher than of rural and urban land, meanwhile microbial related substance accumulated in urban land in comparison with rural and nature land. The multivariate analyses further reveal the relationship between soil physic-chemical properties and SOM composition. These results suggest that urbanization could not only decrease the SOM quantity but also change the SOM composition. The SOM loss caused by urbanization was mainly consist of humic-like substance loss. Besides urbanization also stimulate the accumulation of microbial related substance in SOM which highlight the importance of microorganism is SOM dynamic.

13945. 题目: Effect of Fe2+ addition on chemical oxygen demand and nitrogen removal in horizontal subsurface flow constructed wetlands
文章编号: N18122606
期刊: Chemosphere
作者: Yan Zhang, Xuelan Liu, Chunyan Fu, Xinhua Li, Baixing Yan, Tianhong Shi
更新时间: 2018-12-26
摘要: Horizontal subsurface flow constructed wetlands (CWs) planted with Phragmites australis were set up to analyze the effect of external ferrous iron (Fe2+) addition on chemical oxygen demand (COD) and nitrogen removal. The results showed that external Fe2+ addition has no significant effect on COD removal, while the COD removal efficiencies in CWs with Fe2+ addition were slightly lower than those in CWs without Fe2+ addition, since Fe2+ as an electron donor for denitrification may decrease the consumption of organic carbon. However, external Fe2+ addition significantly enhanced the nitrogen removal capability of the CWs. With an increase in external Fe2+ concentration, the removal efficiencies for total nitrogen (TN), nitrate nitrogen (NO3N), and ammonium nitrogen (NH4N) all increased. The removal efficiencies for TN and NH4N were greatest for an influent Fe2+ concentration of 50 mg L−1, while the greatest removal efficiencies for NO3N were observed at an influent Fe2+ concentration of 150 mg L−1. With increasing hydraulic retention time (HRT), the COD and NO3N removal efficiencies in the CWs with external Fe2+ addition increase sharply and then became stable, while the removal efficiency for TN exhibited a continuous increase. The removal efficiency for NH4N was greatest at an HRT of 5 d–7 d with Fe2+ addition. The change in pH with increasing HRT indicated that external Fe2+ addition did not significantly affect the pH value of the effluent water, but that the wetland systems caused an increase in effluent pH. Fe2+ addition remarkably reduced the oxygen-reduction potential of both the influent and effluent water, which was beneficial to denitrification of microorganisms.
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13946. 题目: From the Titanic and other shipwrecks to biofilm prevention: The interesting role of polyphenol-protein complexes in biofilm inhibition
文章编号: N18122605
期刊: Science of The Total Environment
作者: Eyal Kurzbaum, Luba Iliasafov, Luba Kolik, Jeana Starosvetsky, Dragoljub Bilanovic, Monica Butnariu, Robert Armon
更新时间: 2018-12-26
摘要: Bacteria attach themselves either reversibly or irreversibly onto practically any surface in aqueous and other environments in order to reproduce, while generating extracellular polymeric substances (EPS) as a supportive structure for biofilm formation. Surfaces with a potential to prevent cellular attachment and aggregation (biofilm) would be extremely useful in environmental, biotechnological, medical and industrial applications. The scientific community is currently focusing on the design of micro- and nano-scale textured surfaces with antibacterial and/or antifouling properties (e.g., filtration membranes).Several serum and tissue proteins promote bacterial adhesion (for example, albumin, fibronectin and fibrinogen), whereas polyphenols form complexes with proteins which change their structural, functional and nutritional properties. For example, tannic acid, a compound composed of polygalloyl glucoses or polygalloyl quinic acid esters and several galloyl moieties, inhibits the growth of many bacterial strains.The present review is based on different nautical archaeology research data, and asks a simple but as yet unanswered question: What is the chemistry that prevents leather biodegradation by environmental bacteria and/or formation of biofilms Future research should answer these questions, which are highly important for biofilm prevention.
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13947. 题目: Quantifying biochar content in a field soil with varying organic matter content using a two-temperature loss on ignition method
文章编号: N18122604
期刊: Science of The Total Environment
作者: Seyyed Ali Akbar Nakhli, Sriya Panta, Joseph D. Brown, Jing Tian, Paul T. Imhoff
更新时间: 2018-12-26
摘要: While the use of biochar as a soil amendment for agronomic and environmental management is gaining popularity, quantification of biochar in soil is still challenging. The objective of this work was to develop a fast, simple and inexpensive method to quantify biochar content in field soil with varying organic matter content – the two-temperature loss on ignition (LOI) method. In this approach, biochar mass fraction in a biochar-amended soil is computed by measuring the dry mass of biochar/soil mixture after heating sequentially at two temperatures: low temperature (LT), and high temperature (HT). This method requires the LOI profile for pure soil and pure biochar that are representative of soil and biochar in the field. Although the soil LOI profile may vary due to spatial variation in soil organic matter (SOM) content, the method only requires that the relative soil LOI at LT with respect to LOI at HT is uniform because of similarity in SOM chemical composition. In this method, LT and HT are selected such that the maximum difference in LOI exists at these temperatures between pure soil and biochar. The method was tested by quantifying the biochar content in roadway filter strips with and without a wood biochar pyrolyzed at high temperature (550 °C). The estimates of biochar content from the method matched independent measurements for soils with low (−0.23 ± 0.09 CI%, CI = 95% confidence interval, versus actual 0%) and high (3.9 ± 0.3 CI% versus actual 4.0 ± 1.1 CI%) biochar mass fraction. The method is applicable when SOM content is low to moderate (e.g. <15%) and mostly composed of labile organic compounds, and when biochars are pyrolyzed at moderate to high temperatures (i.e. >400 °C) and composed of relatively low ash content (e.g. <30%).
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13948. 题目: Predicting dissolved organic carbon partition and distribution coefficients of neutral and ionizable organic chemicals
文章编号: N18122603
期刊: Science of The Total Environment
作者: Chiara Maria Vitale, Antonio Di Guardo
更新时间: 2018-12-26
摘要: Estimating KDOC (dissolved organic carbon/water partition coefficient) and DDOC (dissolved organic carbon/water distribution coefficient) of neutral and ionizable organic chemicals is a crucial task for assessing mobility, modelling transport, environmental fate of a variety of chemicals and for evaluating their bioavailability in terrestrial and aquatic environments. A critical literature search of reliability-selected KDOC and DDOC values was performed to setup novel predictive relationships for KDOC and DDOC of neutral and ionizable organic chemicals. This goal was pursued by using: 1) LSER (linear solvation energy relationship) models to predict KDOC for neutral chemicals using Abraham solute parameters calculated for different DOC sources (all DOC sources together, soil porewater, surface water, wastewater and Aldrich humic acid (HA)); 2) linear regressions for predicting DDOC of organic acids from the octanol/water partition coefficient (Log KOW or Log P) and the dissociation constant (pKa), accounting separately for the contribution of the neutral and ionic fraction. The proposed models predicted Log KDOC and DDOC values within a root mean square deviation (RMSD) generally smaller than 0.3 log units.
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13949. 题目: Iron stability on the inner wall of prepared polyethylene drinking pipe: Effects of multi-water quality factors
文章编号: N18122602
期刊: Science of The Total Environment
作者: Jiaying Wang, Hexiang Yan, Kunlun Xin, Tao Tao
更新时间: 2018-12-26
摘要: Iron is currently one of the main contaminants of drinking water. The inner walls of drinking pipes can cause iron to release in water chemistry, which alters the water quality, including its chloride, sulfate, bicarbonate, pH, and humic acid (HA) levels. Hence, the goal of this research was to improve our understanding of the multi-water quality factors affecting iron release in polyethylene pipes. An array of bench-scale experiments were conducted exposing model water with different concentrations of chloride, sulfate, bicarbonate, HA, and different pH levels to prepared polyethylene pipes following the response surface methodology. The single role of HA during iron release is also evaluated by changing its concentration. A comprehensive study revealed that regression models could be used to describe the relationship between the five water quality parameters and iron release. The coefficients of determination were 0.890 and 0.870 for the fitting equations of total and soluble iron concentrations in water, respectively. In the presence of HA, the concentration of iron in water increased more rapidly than that for the other four factors (chloride, sulfate, bicarbonate, and pH). In addition, the Visual MINTEQ results suggest that a lower HA concentration tended to increase the degree of saturation of iron solids. In turn, this limits iron release and considerably increases the iron concentration in water.
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13950. 题目: Economic losses of carbon emissions from circum-Arctic permafrost regions under RCP-SSP scenarios
文章编号: N18122601
期刊: Science of The Total Environment
作者: Yating Chen, Aobo Liu, Zhihua Zhang, Chris Hope, M. James C. Crabbe
更新时间: 2018-12-26
摘要: Under rapid Arctic warming, the vast amount of labile organic carbon stored in Arctic permafrost soils poses a potentially huge threat. Thawing permafrost will release hundreds of billion tons of soil carbon into the atmosphere in the form of CO2 and CH4 that would further intensify global warming and bring more challenges to human society. In this study, we use the PInc-PanTher model to estimate carbon emissions from thawing permafrost in the circum-Arctic during 2010–2100 followed by the PAGE09 integrated assessment model to evaluate the net economic losses caused by these permafrost carbon emissions. Our results show that in terms of net present value (NPV), the release of CO2 and CH4 from circum-Arctic permafrost will generate estimated net economic losses of US$2.5 trillion (5–95% range: 0.3–11.2 US$ trillion) under the RCP4.5-SPP1 scenario and US$12.7 trillion (5–95% range: 1.6–41.8 US$ trillion) under the RCP8.5-SPP3 scenario between 2010 and 2100, which contribute ~4.9% and ~6.4% respectively of net economic losses of global carbon emissions.
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13951. 题目: Substituted Aromatic-Facilitated Dissemination of Mobile Antibiotic Resistance Genes via an Antihydrolysis Mechanism Across an Extracellular Polymeric Substance Permeable Barrier
文章编号: N18122509
期刊: Environmental Science & Technology
作者: Weijun Shou, Fuxing Kang, Shuhan Huang, Chunyao Yan, Jiaxin Zhou, Yijin Wang
更新时间: 2018-12-25
摘要: Mobile antibiotic resistance genes (ARGs) in environmental systems may pose a threat to public health. The coexisting substituted aromatic pollutants may help the ARGs cross the extracellular polymeric substance (EPS) permeable barrier into the interior of cells, facilitating ARG dissemination, but the mechanism is still unknown. Here, we demonstrated that a specific antihydrolysis mechanism of mobile plasmid in the extracellular matrix makes a greater contribution to this facilitated dissemination. Specifically, fluorescence microtitration with a Tb3+-labeled pUC19 plasmid was used to study the formation of substituted aromatic–plasmid complexes associated with ARG dissemination. Manipulations of the endA gene and an EPS confirmed that these forming complexes antagonize the EPS-mediated hydrolysis of the plasmid. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and computational chemistry demonstrated that substituents alter the polarity of aromatic molecules, making the carbon at the 6-position of 1,3-dichlorobenzene as well as the labile protons (−NH2/–OH) of m-phenylenediamine, aniline, and 2-naphthol interact with the deprotonated hydroxy group of the phosphate (P–O···H–C/N/O), mainly via hydrogen bonds. Linear correlations among ARG disseminations, association constants, and bonding energies highlight the quantitative dependency of ARG proliferation on a combination of functionalities templated by d-ribose–phosphate.
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13952. 题目: Real-Time Monitoring of Ligand Exchange Kinetics on Gold Nanoparticle Surfaces Enabled by Hot Spot-Normalized Surface-Enhanced Raman Scattering
文章编号: N18122508
期刊: Environmental Science & Technology
作者: Haoran Wei, Weinan Leng, Junyeob Song, Chang Liu, Marjorie R. Willner, Qishen Huang, Wei Zhou, Peter J. Vikesland
更新时间: 2018-12-25
摘要: Nanoparticle surface coatings dictate their fate, transport, and bioavailability. We used a gold nanoparticle–bacterial cellulose substrate and “hot spot”-normalized surface-enhanced Raman scattering (HSNSERS) to achieve in situ and real-time monitoring of ligand exchange reactions on the gold surface. This approach enables semiquantitative determination of citrate surface coverage. Following exposure of the citrate-coated nanoparticles to a suite of guest ligands (thiolates, amines, carboxylates, inorganic ions, and proteins), the guest ligand signal exhibited first-order growth kinetics, while the desorption mediated decay of the citrate signal followed a first-order model. Guest ligand functional group chemistry dictated the kinetics of citrate desorption, while the guest ligand concentration played only a minor role. Thiolates and BSA were more efficient at ligand exchange than amine-containing chemicals, carboxylate-containing chemicals, and inorganic salts due to their higher binding energies with the AuNP surface. Amine-containing molecules overcoated rather than displaced the citrate layer via electrostatic interaction. Citrate exhibited low resistance to replacement at high surface coverages, but higher resistance at lower coverage, thus suggesting a transformation of the citrate-binding mode during desorption. High resistance to replacement in streamwater suggests that the role of surface-adsorbed citrate in nanomaterial fate and transport must be better understood.
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13953. 题目: Direct Evidence for Temporal Molecular Fractionation of Dissolved Organic Matter at the Iron Oxyhydroxide Interface
文章编号: N18122507
期刊: Environmental Science & Technology
作者: Elizabeth K. Coward, Tsutomu Ohno, Donald L. Sparks
更新时间: 2018-12-25
摘要: While the importance of organic matter adsorption onto reactive iron-bearing mineral surfaces to carbon stabilization in soils and sediments has been well-established, fundamental understanding of how compounds assemble at the mineral interface remains elusive. Organic matter is thought to layer sequentially onto the mineral surface, forming molecular architecture stratified by bond strength and compound polarity. However, prominent complexation models lack experimental backing, despite the role of such architecture in fractionated, compound-dependent persistence of organic matter and modulating future perturbations in mineral stabilization capacity. Here, we use kinetic assays and ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry under high temporal frequency to directly detect the molecular partitioning of organic matter onto an iron oxyhydroxide during adsorption. We observed three sequential intervals of discrete molecular composition throughout the adsorption reaction, in which rapid primary adsorption of aromatic compounds was followed by secondary lignin-like and tertiary aliphatic compounds. These findings, paired with observed differential fractionation along formulas nitrogen and oxygen content and decreasing selective sorption with reaction time, support “zonal” assembly models. This work presents direct detection of sequential molecular assembly of organic matter at the mineral interface, an important yet abstruse regulator of carbon stabilization and composition across temporal and spatial scales.
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13954. 题目: Is vermicompost the possible in situ sorbent? Immobilization of Pb, Cd and Cr in sediment with sludge derived vermicompost, a column study
文章编号: N18122506
期刊: Journal of Hazardous Materials
作者: Yaxin Zhang, Ye Tian, Duofei Hu, Jinshi Fan, Maocai Shen, Guangming Zeng
更新时间: 2018-12-25
摘要: The goal of this study was to investigate the immobilization effect of vermicomposted sewage sludge for Pb, Cd and Cr in the sediment under simulated in situ conditions using column test. Positioning 10 % dw of vermicompost at the bottom layer of the column resulted in an average decrease of Pb, Cd and Cr in the leachate of 93, 97 and 75.5 %, with the accumulated adsorbed amount of 11.80, 4.81 and 5.62 mg g-1, respectively. Fluorescence Excitation‒Emission Matrix (EEM) combined with parallel factor analysis (PARAFAC) was adopted to identify the components in DOM (dissolved organic matter) that were efficient for the immobilization of heavy metals. The 4‒component PARAFAC model established showed that DOM was dominated by a protein‒like material (component C1), and three humic‒like materials (component C2, C3 and C4). The humic substances formed the organo‒metal complexes with Pb, Cr and Cd, hence, the metal ions were sequestered by the sorbent. Also, as calculated by the bivariate coefficients, the C2/C1 ratios can be liable parameters for assessing the retaining capability of vermicompost for heavy metals. Generally, vermicompost can be used as a promising in situ sorbent for the remediation of heavy metal polluted sediments.

13955. 题目: Centennial-scale climate variability during the past 2000 years derived from lacustrine sediment on the western Tibetan Plateau
文章编号: N18122505
期刊: Quaternary International
作者: Xiumei Li, Mingda Wang, Juzhi Hou
更新时间: 2018-12-25
摘要: The Tibetan Plateau (TP) climate change has been suggested to be modulated by the Asian monsoon and the westerly jet at seasonal, decadal, millennial and glacial-interglacial scales, which demonstrated evident regional variation. However, due to the lack of high resolution climate records, how the climate changed and how the regional environment was influenced by the monsoon and the westerlies on the western Tibetan Plateau (WTP) during the late Holocene remains unclear. Here we present multiple palaeo-climatic proxy records in sediment core from Xiada Co in the WTP for the past 2000 years, based on the relative distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs), n-alkanoic acid average chain length (ACL) and percent aquatic inputs (Paq), XRF, total organic carbon (TOC) and inorganic carbon (TIC) concentration. The centennial-scale variation of the climate records captures well-known climatic events over the past 2000 years, for example, the cool-dry ‘Little Ice Age’ (LIA) and the warm-wet ‘Medieval Warm Period’ (MWP). Besides, the multi-proxy indicated a severe dry event during 350-250 cal yr BP and a cool-wet climate during the past 200 years. This study concludes that Xiada Co was mainly influenced by the Indian monsoon during the past 2000 years. In addition, the temperature variability appears to correspond to solar irradiance changes, suggesting a significant solar influence on temperature variability in the WTP. Our results suggest that the abrupt drought near 320 cal yr BP may be the key factor leading to the demise of the Guge Kingdom.

13956. 题目: Characteristics of nitrogen and phosphorus adsorption by Mg-loaded biochar from different feedstocks
文章编号: N18122504
期刊: Bioresource Technology
作者: Yan-Hong Jiang, An-Yu Li, Hua Deng, Cheng-Hui Ye, Yu-Qing Wu, Yu-Dan Linmu, Hao-Lin Hang
更新时间: 2018-12-25
摘要: Herein, biochars from 6 different feedstocks (taro straw, corn straw, cassava straw, Chinese fir straw, banana straw, and Camellia oleifera shell) were produced using magnesium chloride (MgCl2) as a modifier due to their sorption behavior toward NH4+-N and phosphorus in an aqueous solution.The biochar characteristics were evaluated, including pH, pHPZC, biochar magnesium content, and total pore volume (PVtot). The experimental results in terms of the kinetics and equilibrium isotherms showed that the cassava straw and banana straw biochars exhibited the theoretical maximum saturated adsorption capacities of 24.04 mg·g-1 (NH4+-N) and 31.15 mg·g-1 (TP), respectively. Biochar produced from these feedstocks had higher magnesium contents and greater total pore volumes, reflecting the significant contributions from magnesium and steric effects. FTIR, XRD, and SEM/EDS analyses demonstrated that NH4+-N and TP sorption mechanisms predominantly involved surface electrostatic attraction, Mg2+ precipitates and complexation with surface hydroxyl functional groups.
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13957. 题目: Kinetic and microbial response of activated sludge community to acute and chronic exposure to tetracycline
文章编号: N18122503
期刊: Journal of Hazardous Materials
作者: Ilke Pala-Ozkok, Emine Ubay-Cokgor, Daniel Jonas, Derin Orhon
更新时间: 2018-12-25
摘要: Current study aimed to discover both kinetic and microbial response of activated sludge biomass to continuous exposure to tetracycline, one of the most frequently detected antibiotics in wastewaters. Respirometric analysis and model evaluation of the oxygen utilization rate profiles generated at critical phases of the experimental period showed that, continuous exposure to tetracycline caused complete suppression of substrate storage aside from mild inhibition on the growth kinetics and it exerted a significant binding action with available organic carbon, leading to less oxygen consumption. Additionally, increase in endogenous decay rates by 1.5 fold was associated with maintenance energy dictated by the presence and production of antibiotic resistance genes, as demonstrated by resistance gene profile. High-throughput sequencing results showed that continuously exposure to tetracycline caused a significant shift in the community structure at species level so that tetracycline resistant bacteria like Arthrobacter sp and Diaphorobacter sp dominated the bacterial community.

13958. 题目: Saltwater intrusion and soil carbon loss: Testing effects of salinity and phosphorus loading on microbial functions in experimental freshwater wetlands
文章编号: N18122502
期刊: Geoderma
作者: Shelby Servais, John S. Kominoski, Sean P. Charles, Evelyn E. Gaiser, Viviana Mazzei, Tiffany G. Troxler, Benjamin J. Wilson
更新时间: 2018-12-25
摘要: Wetlands can store significant amounts of carbon (C), but climate and land-use change increasingly threaten wetland C storage potential. Carbon stored in soils of freshwater coastal wetlands is vulnerable to rapid saltwater intrusion associated with sea-level rise and reduced freshwater flows. In the Florida Everglades, unprecedented saltwater intrusion is simultaneously exposing wetlands soils to elevated salinity and phosphorus (P), in areas where C-rich peat soils are collapsing. To determine how elevated salinity and P interact to influence microbial contributions to C loss, we continuously added P (~0.5 mg P d−1) and salinity (~6.9 g salt d−1) to freshwater Cladium jamaicense (sawgrass) peat monoliths for two years. We measured changes in porewater chemistry, microbial extracellular enzyme activities, respiration rates, microbial biomass, root litter breakdown rates (k), and soil elemental composition after short (57 d), intermediate- (392 d), and long-term (741 d) exposure. After 741 days, both β-1,4-glucosidase activity (P < 0.01) and β-1,4-cellobiosidase activity (P < 0.01) were reduced with added salinity in soils at 7.5–15 cm depth. Soil microbial biomass C decreased by 3.6× at 7.5–15 cm (P < 0.01) but not 0–7.5 cm depth (P > 0.05) with added salinity and was unaffected by added P. Soil respiration rates decreased after 372 d exposure to salinity (P = 0.05) and did not change with P exposure. Root litter k increased by 1.5× with added P and was unaffected by salinity exposure (P > 0.01). Soil %C decreased by approximately 1.3× after 741 days of salinity exposure compared to freshwater controls (P < 0.01). Elevated salinity and P accelerated wetland soil C loss primarily through leaching of DOC and increased root litter k. Our results indicate that freshwater wetland soils are sensitive to short- and long-term exposure to saltwater intrusion. Despite suppression of some soil microbial processes with added salinity, salt and P exposure appear to drive net C losses from coastal wetland soils.

13959. 题目: Organic carbon dynamics in soils of Mid-Atlantic barrier island landscapes
文章编号: N18122501
期刊: Geoderma
作者: Ann M. Rossi, Martin C. Rabenhorst
更新时间: 2018-12-25
摘要: Geomorphic processes associated with coastal wetlands often result in high carbon accumulation rates and relatively large carbon stocks. Barrier islands are an important component of coastal ecosystems and freshwater and brackish wetlands on these islands provide an important habitat for a number of animal and plant species. However, organic carbon dynamics in these landscapes have received relatively little attention. The objective of this study was to document the accumulation of organic carbon and understand the factors influencing soil carbon dynamics on barrier islands. Ten topographic transects were established on different landforms on Assateague Island National Seashore, MD, USA. Soil organic carbon stocks, aboveground carbon inputs, and decomposition rates were compared among landforms (representing differing degrees of landform stability and soil age) and drainage conditions. Soil organic carbon stocks (0–1.0 m) ranged from 0.49 to 18.8 kg C m−2, and increased in magnitude with soil age. Higher carbon stocks in the older soils were partly attributed to the increased time over which carbon had accumulated. Additionally, a shift from herbaceous dominated to forest dominated plant communities led to greater carbon inputs in older soils. Carbon stocks were also greater in the very poorly and poorly drained soils (relative to drier soils) where high levels of carbon inputs (plant biomass) exceed decomposition rates, which were slowed under anaerobic conditions. While rates of carbon accumulation (average 0.021 kg C m−2 yr−1) are somewhat low compared to other more productive systems, barrier island soils have the potential to store large amounts of organic carbon (relative to other soils) as organic-rich surface horizons are buried during overwash events.

13960. 题目: UV-activated persulfate oxidation of 17β-estradiol: Implications for discharge water remediation
文章编号: N18122402
期刊: Journal of Environmental Chemical Engineering
作者: A. Angkaew, C. Sakulthaew, T. Satapanajaru, C. Chokejaroenrat
更新时间: 2018-12-24
摘要: The female sexual hormone, 17β-estradiol (E2), was chosen as a model emerging contaminant to study its degradation kinetics using UV-activated persulfate (UV/PS). Our objective was to quantify the effectiveness of UV/PS coupled with slow-release technology to degrade E2 in real wastewater using a systematic design flow-through system. This was accomplished by quantifying the effects on E2 degradation rates of the initial PS or E2 concentration, initial pH, constituent ions, turbidity, humic acids, and real wastewater. The results showed that the E2 degradation rates increased with increasing PS concentration. The presence of other constituent ions (NO3–, Cl–, HCO3–) resulted in varying degradation rates due to the formation of active and less reactive radicals. Humic acid had higher significant impact on the rates than did turbidity. In addition, the observed degradation rates (0.140 min-1) in Deionized water were much higher than those observed in real wastewater matrix (0.001 min-1). Biodegradable soywax was the best binding agent that provided sustained delivery of PS thus resulting in better E2 removal than with other waxes. But treating E2 with PS soywax in a wastewater matrix, our flow-through system was able to maintain the E2 concentration below 50% in the contact tank (~150 min) and able to continually remove E2 up to 65% (~240 min) in the effluent reservoir. The overall results supported the use of UV-activated slow-release PS to treat discharge water in animal farming.

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