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22741. 题目: The impacts of metal ions on phytotoxicity mediate by microbial community during municipal solid waste composting
文章编号: N19050507
期刊: Journal of Environmental Management
作者: Xinyu Zhao, Beidou Xi, Xiaosong He, Dan Li, Wenbing Tan, Hui Zhang, Xiaowei Wang, Chao Yang
更新时间: 2019-05-05
摘要: Metal ions (MIs) are the main sources of phytotoxicity of compost product, which can be absorbed by plants, thereby reducing the germination rate. The aim of this study was to analyze the interactional mechanism among MIs, microbial community, the structure of water soluble organic matter and phytotoxicity during composting. The results indicated that phytotoxicity was positively correlated with MIs (II) (As, Cd, Hg, Cr, Fe, Mn and Pb), and negatively correlated with MIs (I) (Mg, Zn, Ni and Cu). Furthermore, SO₄²⁻, organic matter (OM), pH and four bacterial species significantly influenced the association of MIs to phytotoxicity. Additionally, molecular weight, protein-like substance and oxygen-containing functional groups relating to MIs (II) were significantly influenced by the nine bacterial species. Based on the response of physicochemical parameters on these key bacterial species, three possible mutual mechanisms were proposed using the structural equation model. Accordingly, a regulating method was proposed to reduce the phytotoxicity during composting.
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22742. 题目: Identification of oxidative stress and estrogenic activity induced by polarity fractions of effluent organic matter
文章编号: N19050506
期刊: Journal of Hazardous Materials
作者: Jisu Yoo, Jin Hur, Jinho Jung
更新时间: 2019-05-05
摘要: This study evaluated oxidative stress and estrogenic activity induced by hydrophobic (HP), transphilic (TP), and hydrophilic (HL) fractions of effluent organic matter (EfOM) from municipal and industrial wastewater treatment plants. Fluorescence regional integration (FRI) analysis indicated that EfOM showed higher FRI distribution in regions II (aromatic protein-like) and IV (soluble microbial products, SMPs) than Suwannee River natural organic matter (SRNOM), which was primarily in regions III (fulvic acid-like) and V (humic acid-like). The HP and HL fractions of industrial EfOMs significantly increased catalase (CAT) and glutathione S-transferase (GST) activity and lipid peroxidation compared with those of the control (p < 0.05). Estrogenic activity was the highest in industrial EfOM followed by municipal EfOM, and both were significantly higher than that of SRNOM and the control (p < 0.05). FRI distribution in region II was significantly related to CAT, GST, and estrogenic activity (r = 0.7142, 0.7786, and 0.8107, respectively) for the HL fraction of EfOM. For the HP fraction of EfOM, regions II and IV were significantly related to estrogenic activity (r = 0.7221 and 0.6707, respectively). These findings suggest that aromatic protein-like substances and SMPs in EfOM were responsible for the observed oxidative stress and estrogenic activity.

22743. 题目: Are light-dark coupled laminae in lacustrine shale seasonally controlled? A case study using astronomical tuning from 42.2 to 45.4 Ma in the Dongying Depression, Bohai Bay Basin, eastern China
文章编号: N19050505
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Ke Zhao, Xuebin Du, Yongchao Lu, Shipeng Xiong, Yong Wang
更新时间: 2019-05-05
摘要: As a typical sedimentary structure in fine-grained rocks, laminae are widely distributed in shales and mudstones in sedimentary basins. The Shahejie Formation (42.2–45.4 Ma) formed during the Eocene of the Paleogene in the Dongying Depression of China is recognized as a typical area to study lacustrine shale. According to the composition of different lamina, four types of couplets are identified, including carbonate-clay couplets, carbonate-organic couplets, clay-organic couplets and carbonate-clay-organic triplets. All couplets are composed of light and dark layers. A combination of core images, microscopic observations, mineral compositions, geochemical data, carbon and oxygen isotopes, and strontium isotopes verifies that the laminae are primarily developed in a saline and anoxic, or even euxinic environment, with a high organic matter (OM) flux. Through astronomical cycle analysis of the natural gamma ray (GR) curve from sample site well NY1, the data suggest that the lacustrine shale laminae are formed annually with an average duration of 1.34 yr. The formation of laminae is affected by the season, which is closely related to the seasonal growth and death of algae. During the period of algae growth, a large number of light-colored carbonate laminae are deposited, whereas when the algae dies, organic matter accumulates at the bottom of lakes and forms dark organic-rich laminae. The interbedded and lenticular laminae, which are subdivided by layering characteristics, are primarily affected by diagenesis in postdepositional processes. Study of the laminae is helpful in understanding the formation process of lacustrine shale, and it provides invaluable sources of information for paleoclimate reconstruction.

22744. 题目: Biochar significantly alters rhizobacterial communities and reduces Cd concentration in rice grains grown on Cd-contaminated soils
文章编号: N19050504
期刊: Science of The Total Environment
作者: Runze Wang, Shuai Wei, Peihan Jia, Ting Liu, Dandi Hou, Ruohan Xie, Zhi Lin, Jun Ge, Yabei Qiao, Xiaoyan Chang, Lingli Lu, Shengke Tian
更新时间: 2019-05-05
摘要: Cadmium (Cd) contamination poses a serious problem in paddy soils. Biochar is frequently reported to deactivate Cd in soils and reduce Cd accumulation in rice plants, but few studies have addressed whether and how biochar affected the microbial communities in rice rhizosphere, which was an important factor determining the metal bioavailability and plant growth. In this study, biochar was pyrolyzed from bamboo (Phyllostachys heterocycla) chips at 350 °C. By using ICP-MS analysis and 16S rRNA gene sequencing, the impact of the biochar on Cd uptake by rice and on rhizospheric bacterial communities was investigated in both high-accumulating (HA) and low-accumulating (LA) rice cultivars grown in soils artificially contaminated with different Cd levels. Applied biochar significantly reduced Cd contents in rice plants of both cultivars, with substantially lower grain Cd contents for LA grown in highly contaminated soil. Soil pH was slightly increased by the applied biochar. Cd bioavailability was somehow reduced in soils, but not as significant as the reduction of Cd contents in rice plants. More interestingly, biochar application significantly altered the rhizobacterial community: it stimulated growth-promoting bacteria, such as Kaistobacter, Sphingobium (order Sphingomonadales), and Rhizobiaceae (order Rhizobiales); improved natural barrier formation and the transformation of metal mobilization around the rhizosphere mediated by, e.g., Rhodocyclaceae (class Betaproteobacteria) and Geobacter (class Deltaproteobacteria); and enhanced colonization of the LA rhizosphere possibly by taxa involved in Cd immobilization (Desulfovibrionales and Desulfobacterales). These results indicate that biochar application significantly reduces Cd uptake and accumulation by altering the rhizosphere bacterial community in rice grown on Cd-contaminated soils. The baseline data generated in this study provide insights that pave the way toward safer rice production.
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22745. 题目: Insights into thermodynamic mechanisms driving bisphenol A (BPA) binding to extracellular polymeric substances (EPS) of activated sludge
文章编号: N19050503
期刊: Science of The Total Environment
作者: Zi-run Yan, Yu-ying Zhu, Hui-shan Meng, Si-yuan Wang, Li-hong Gan, Xiu-yan Li, Juan Xu, Wei Zhang
更新时间: 2019-05-05
摘要: Bisphenol A (BPA) in wastewater has high risks of causing biological feminization. During the wastewater treatment process, large amounts of BPA are accumulated in activated sludge. However, the mechanisms of BPA interacted with activated sludge are still unclear. Especially, the roles of extracellular polymeric substances (EPS), which are major components of activated sludge, in the removal of BPA have never been concerned. In this study, the binding interactions between sludge EPS and BPA are explored combining fluorescence spectroscopy and dynamic light scattering. The thermodynamic mechanisms driving the binding behavior of BPA to EPS are illustrated by isothermal titration calorimetry. The results indicate that the binding interaction between BPA and EPS is spontaneous. BPA mainly binds with the proteins of EPS by hydrophobic association. The random-coiled structure of EPS transforms into relatively condensed cores after binding with BPA. A neutral pH, high ionic strength, and high temperature promote the binding process, facilitating to stabilize BPA in sludge EPS. This study provides new insights into the roles of sludge EPS in the migration and removal of BPA in activated sludge system.
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22746. 题目: Biochar and denitrification: Examining the effect of a biochar temperature series on the kinetics of gaseous N turnover. Which properties matter?
文章编号: N19050502
期刊: Soil Biology and Biochemistry
作者: Simon Weldon, Daniel P. Rasse, Alice Budai, Oliver Tomic, Peter Dörsch
更新时间: 2019-05-05
摘要: Biochar has been shown to reduce nitrous oxide (N₂O) emissions from soils, but the effect is highly variable across studies and the mechanisms are under debate. To improve our mechanistic understanding of biochar effects on N₂O emission, we monitored kinetics of NO, N₂O and N₂ accumulation in anoxic slurries of a peat and a mineral soil, spiked with nitrate and amended with feedstock dried at 105 °C and biochar produced at 372, 416, 562 and 796 °C at five different doses. Both soils accumulated consistently less N₂O and NO in the presence of high-temperature chars (BC562 and BC796), which stimulated reduction of denitrification intermediates to N₂, particularly in the acid peat. This effect appeared to be strongly linked to the degree of biochar carbonisation as predicted by the H:C ratio of the char. In addition, biochar surface area and pH were identified as important factors, whereas ash content and CEC played a minor role. At low pyrolysis temperature, the biochar effect was soil dependent, suppressing N₂O accumulation in the mineral soil, but enhancing it in the peat soil. This contrast was likely due to the labile carbon content of low temperature chars, which contributed to immobilise N in the mineral soil, but stimulated denitrification and N₂O emission in the peat soil. We conclude that biochar with a high degree of carbonisation, high pH and high surface area is best suited to supress N₂O emission from denitrification, while low temperature chars risk supporting incomplete denitrification.

22747. 题目: Preferential molecular fractionation of dissolved organic matter by iron minerals with different oxidation states
文章编号: N19050501
期刊: Chemical Geology
作者: Yu Wang, Zheyun Zhang, Lanfang Han, Ke Sun, Jie Jin, Yu Yang, Yan Yang, Zhineng Hao, Jingfu Liu, Baoshan Xing
更新时间: 2019-05-05
摘要: The biogeochemical cycles of iron and dissolved organic matter (DOM) are strongly associated, especially at different oxidation sates. However, the role of iron minerals with different redox states in DOM preservation has not been clearly characterized at the molecular level. In this study, we employed Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) to investigate the molecular fractionation of DOM by adsorption onto four iron minerals with different oxidation states (ferrihydrite, hematite (α-Fe₂O₃), iron sulfide (FeS), and pyrite (FeS₂)). The sorption capacity (normalized to per gram adsorbent) with respect to DOM was in the order of ferrihydrite > iron sulfide > hematite > pyrite. After normalization by specific surface area, the sorption capacity of ferrihydrite plummeted to the second place and was much lower than that of iron sulfide. The sorptive fractionation of DOM was significant for ferrihydrite and iron sulfide but was not obvious for pyrite. Compounds high in unsaturation and nominal oxidation state of carbon or rich in oxygen were preferentially bound to ferrihydrite and iron sulfide, leaving compounds low in unsaturation or poor in oxygenated groups in solution. For DOM containing abundant oxygen functional groups, hematite may result in stronger sorptive fractionation than iron sulfide. These findings provided new insights into the stability of aromatic and aliphatic carbon with various oxygenated groups coupled to redox iron transformation in soils.
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22748. 题目: Mechanistic Insight into the Effect of Metal Ions on Photogeneration of Reactive Species from Dissolved Organic Matter
文章编号: N19050408
期刊: Environmental Science & Technology
作者: Dong Wan, Virender K. Sharma, Lu Liu, Yuegang Zuo, Yong Chen
更新时间: 2019-05-04
摘要: The photogeneration of reactive species (RS) from dissolved organic matter (DOM) exhibits a great impact on the attenuation of pollutants in natural waters. However, the effect of metal ions on the photogeneration of excited triplet-state DOM (³DOM*), singlet oxygen (¹O₂), and hydroxyl radical (^•OH) by effluent organic matter (EfOM), fulvic acid (FA), and humic acid (HA) is poorly understood. Here, we provided the first evidence that the quenching of ³DOM* was positively correlated with the complexation capacity of metal ions with DOM. Generally, the paramagnetic metal ions (Cr³⁺, Mn²⁺, Fe³⁺, and Cu²⁺) exhibited higher conditional stability constants (log K_ML) with DOM and stronger inhibition for RS than the others (Mg²⁺, Ca²⁺, Al³⁺, and Zn²⁺). For DOM of different sources, the metal binding capacity increased in the order of EfOM < HA < FA and the humic substances were more susceptible to metal ions. The inhibition was attributed to both static and dynamic quenching of ³DOM* by metal ions. The dynamic quenching rate constants of metal ions for ³DOM* were estimated as ∼10⁹ M^–1 s^–1, which was positively related to the corresponding log K_ML. These findings highlight crucial links between metal–DOM complexation and ³DOM* quenching and, consequently, the inhibition of RS.

22749. 题目: Release of Heavy Metals from Dolomite Phosphate Rock after Activation with Organic Agent
文章编号: N19050407
期刊: Journal of Environment Quality
作者: Ying Yu, Jibing Xiong, Ruliang Liu, Zhenli He
更新时间: 2019-05-04
摘要: As high-grade phosphate reserves begin to diminish worldwide, low-grade phosphate rock such as that containing dolomite [CaMg(CO3)2] needs to be explored as a potential fertilizer. Activation of dolomite phosphate rock with humic acid substantially increased P availability by chelating Ca2+ and Mg2+. However, the release potential of heavy metals during the activation process should be evaluated. In this study, an orthogonal experiment was designed to investigate the effects of major activating factors on the release of Cd, Cr, Cu, Mn, Ni, Pb, and Zn in activated fertilizers using a batch-equilibrium technique. The release potential of heavy metals from activated fertilizers was further compared with single superphosphate fertilizers made from the same dolomite phosphate rock. The activation process increased water-soluble Cr, Ni, and Zn by 39.8 to 65.7, 26.5 to 35.6, and 6.9 to 14.6 times, respectively, as compared with the original dolomite phosphate rocks, but there was a decrease in water-soluble Cd, Mn, Ni, Pb, and Zn by 1.4 to 5.4, 5.4 to 8.6, 2.3 to 3.7, 0.7 to 2.8, and 2.6 to 5.0 times, respectively, as compared with single superphosphate fertilizers. The release of heavy metals was affected by activating factors including dolomite phosphate rock type, particle size, humic acid dosage, and moisture content. Similar results were obtained with Mehlich-3 extraction, but levels of Mehlich-3-extractable heavy metals were less in activated fertilizers than in the original dolomite phosphate rocks, except Cu. These results indicate that activated fertilizers contain less bioavailable heavy metals than single superphosphate fertilizers and, therefore, are more environmentally friendly for application in agriculture.

22750. 题目: Three-Year Field Observation of Biochar-Mediated Changes in Soil Organic Carbon and Microbial Activity
文章编号: N19050406
期刊: Journal of Environment Quality
作者: Ming Li, Yimin Wang, Ming Liu, Qi Liu, Zubin Xie, Zhongpei Li, Minori Uchimiya, Yaozu Chen
更新时间: 2019-05-04
摘要: Although biochar is considered a promising C sequestration agent, long-term field experiments are lacking to assess the effects of biochar addition on the soil organic C (SOC) and microbial community. Corn (Zea mays L.) straw feedstock and biochar were applied to a sandy loam soil for three consecutive years to investigate the SOC distribution within various fractionations, responses of soil microbial biomass, enzyme activity, and community structure. In comparison with straw amendment, higher levels of biochar (6.0 and 12 t ha⁻¹) significantly increased soil pH, SOC, total N (TN), available P (AP) and available K. Biochar (12 t ha⁻¹) decreased the fulvic acid fraction by 15.9% and increased the free-light C (FLC), intra-aggregate, and organomineral fractionations by 6.05-, 2.52-, and 0.22-fold, respectively. There was no significant influence of straw or biochar application on the soil microbial biomass C (MBC) contents or the activities of soil enzymes. A phospholipid fatty acids assay suggested that 6.0 t ha⁻¹ straw slightly enriched the abundance of Actinobacteria in soil, whereas biochar (6.0 and 12 t ha⁻¹) mainly promoted the growth of Gram-positive bacteria, fungi, and general bacteria groups. Canonical correspondence analysis indicated that soil pH, SOC, TN, AP, FLC, and fulvic acid significantly influence the structure of soil microbial community (r² < −0.50, p < 0.05 for both MBC and the ratio of MBC to SOC; r² > 0.50 for microbial biomass N, basal respiration [BR], and the ratio of BR through incubation to MBC). Established quantitative relationships provided evidence for understanding the effects of biochar amendment on soil environment after a long-term field application.

22751. 题目: New insights into contrasting mechanisms for PAE adsorption on millimeter, micron- and nano-scale biochar
文章编号: N19050405
期刊: Environmental Science and Pollution Research
作者: Shaoqiang Ma, Fanqi Jing, Saran P. Sohi, Jiawei Chen
更新时间: 2019-05-04
摘要: Biochar is being examined as a potential sorbent for organic pollutants in the environment including phthalate esters (PAEs). It has been noted that nano-scale biochar particles displayed stronger migration potential than other particles, which poses the potential risk of pollutant transfer through the environment. In this present study, we examined the influence of sub-millimeter (200–600 μm), micron-scale (10–60 μm), and nano-scale (0.1–0.6 μm) biochar on diethyl phthalate (DEP, as a model) adsorption using particles derived from corn straw and rice husk biochar. Meanwhile, the interaction between adsorption capacity and initial pH was also considered. Our results showed that the adsorption capacity of biochar for DEP increased with decreasing particle size, and was considerably higher for nano-scale biochar than for other particles. This was attributable to its developed pore structure and higher specific surface area (SSA), especially the dominant micropore (292.73 m²/g), suggesting that the adsorption of DEP to nano-scale biochar was dominated by pore-filling rather than π-π EDA and H bonding that was applied to biochar of larger, more typical dimensions. The adsorption capacity of nano-scale biochar for DEP was markedly decreased when initial pH was decreased from 9.0 to 3.0. Because an acid environment could reduce the absolute surface charge on nano-scale biochar, it was easier for the particles to agglomerate. Nano-scale biochar therefore have higher activity in alkaline conditions, which could pose certain risks through their application into the environment.

22752. 题目: Comparative efficiency of peanut shell and peanut shell biochar for removal of arsenic from water
文章编号: N19050404
期刊: Environmental Science and Pollution Research
作者: Muhammad Sohail Sattar, Muhammad Bilal Shakoor, Shafaqat Ali, Muhammad Rizwan, Nabeel Khan Niazi, Asim Jilani
更新时间: 2019-05-04
摘要: Contamination of surface water and groundwater streams with carcinogenic chemicals such as arsenic (As) has been a major environmental issue worldwide, and requires significant attention to develop new and low-cost sorbents to treat As-polluted water. In the current study, arsenite (As(III)) and arsenate (As(V)) removal efficiency of peanut shell biochar (PSB) was compared with peanut shell (PS) in aqueous solutions. Sorption experiments showed that PSB possessed relatively higher As removal efficiency than PS, with 95% As(III) (at pH 7.2) and 99% As(V) (at pH 6.2) with 0.6 g L⁻¹ sorbent dose, 5 mg L⁻¹ initial As concentration, and 2 h equilibrium time. Experimental data followed a pseudo-second-order model for sorption kinetics showing the dominance of chemical interactions (surface complexation) between As and surface functional groups. The Langmuir model for sorption isotherm indicated that As was sorbed via a monolayer sorption process. The X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy analyses revealed that the hydroxyl (–OH) and aromatic surface functional (C=O, C=C–C, and –C–H) groups contributed significantly in the sorption of both As species from aqueous solutions through surface complexation and/or electrostatic reactions. We demonstrate that the pyrolysis of abandoned PS yields a novel, low-cost, and efficient biochar which provides dual benefits of As-rich water treatment and a value-added sustainable strategy for solid waste disposal.

22753. 题目: Maize (Zea mays) growth and nutrient uptake following integrated improvement of vermicompost and humic acid fertilizer on coastal saline soil
文章编号: N19050403
期刊: Applied Soil Ecology
作者: Mengli Liu, Chong Wang, Fuyou Wang, Yongjin Xie
更新时间: 2019-05-04
摘要: Soil salinity, poor soil structure and macronutrient deficiencies are three important limitations responsible for poor crop yields in coastal saline soil. Therefore, the objective was to investigate the integrated effects of humic acid fertilizer and vermicompost on maize growth and nutrient uptake in coastal saline soil. The experiment included three treatments: (1) control without humic acid fertilizer and vermicompost (CK); (2) treatment with humic acid fertilizer (H); (3) treatment with vermicompost (V). Soil salinity, aggregates, nutrient availability and uptake, the soil microbial community from next-generation high-throughput sequencing, maize biomass and yield were determined in this study. The results showed that humic acid fertilizer and vermicompost increased soil macroaggregates by 77.59–125.58% and 35.02–91.02%, respectively, which could efficiently decrease soil salinity. Proteobacteria, Actinobacteria and Acidobacteria were the dominant bacterial phyla, and Ascomycota was the dominant fungal phylum in this coastal saline soil. The humic acid fertilizer and vermicompost could affect the fungal community structure in the six-leaf stage (6S) and the bacterial community structure in the harvest stage (HS), which consequently improved soil nutrient availability and maize nutrient uptake. The humic acid fertilizer and vermicompost could enhance nitrogen (N) nutrient absorption of the maize plant in the vegetative growth period (6S) and the phosphorus (P) and potassium (K) nutrient absorption in the reproductive growth period (tasseling stage (TS) and harvest stage (HS)) of maize, which played an important role in increasing the maize yield in coastal saline soil. Therefore, the application of humic acid fertilizer and vermicompost can be integrated as a practice for improving coastal saline soil.

22754. 题目: Biochar decreases soil N₂O emissions in Moso bamboo plantations through decreasing labile N concentrations, N-cycling enzyme activities and nitrification/denitrification rates
文章编号: N19050402
期刊: Geoderma
作者: Yuze Song, Yongfu Li, Yanjiang Cai, Shenglei Fu, Yu Luo, Hailong Wang, Chenfei Liang, Ziwen Lin, Shuaidong Hu, Yongchun Li, Scott X. Chang
更新时间: 2019-05-04
摘要: Biochar application has been shown to be effective in mitigating soil N₂O emission in agricultural soils. However, the effect of biochar on soil N₂O emission in subtropical plantations and the underlining mechanisms are poorly understood. The objective of this study was to investigate the effect of biochar application rates (0, 5 and 15 t ha⁻¹) on soil properties and N₂O emissions within a Moso bamboo (Phyllostachys edulis) plantation in a 24-month field trial. Biochar application significantly (P < 0.05) decreased soil N₂O emission, with the reduction rate positively related to the biochar application rate. The reduction in N₂O emission by biochar application diminished over time. Biochar did not affect soil temperature (at 5 cm depth), and there were no significant relationships between N₂O emission and either soil moisture content or soil microbial biomass C. However, biochar application significantly (P < 0.05) increased the water soluble organic C but decreased soil NH₄⁺-N, NO₃⁻-N and water soluble organic N (WSON) concentrations, soil urease and protease activities, and soil gross nitrification and denitrification rates. Soil N₂O flux was positively (P < 0.05) correlated with soil NH₄⁺-N, NO₃⁻-N and WSON concentrations, soil urease and protease activities, and soil gross nitrification and denitrification rates, regardless of the treatment. Structural equation modeling suggests that biochar application decreased soil N₂O emissions directly by decreasing soil gross nitrification and denitrification rates, and indirectly by decreasing concentrations of NH₄⁺-N, NO₃⁻-N and WSON, and the activities of urease and protease. We conclude that biochar application decreased soil N₂O emission in the Moso bamboo plantation by decreasing labile N concentrations, N-cycling enzyme activities and nitrification/denitrification rates. Our findings suggest that biochar application can be an effective method to mitigate soil N₂O emission in subtropical plantations.

22755. 题目: Aridity-controlled hydrogen isotope fractionation between soil n-alkanes and precipitation in China
文章编号: N19050401
期刊: Organic Geochemistry
作者: Yangyang Li, Shiling Yang, Pan Luo, Shangfa Xiong
更新时间: 2019-05-04
摘要: Leaf-wax n-alkane hydrogen isotope composition (δD_alk) is widely applied as a proxy for paleohydroclimatic changes, but the factors controlling δD_alk remain to be clarified. In this study, in order to determine the dominant controls, we measured δD_alk in 54 surface soils along a southeast–northwest transect across a steep climatic gradient in China. δD_alk is positively correlated with annual precipitation δD (δD_pann) and better correlated with growing season (April–October) precipitation δD (δD_pgs). However, the variability of δD_pann (38‰) and δD_pgs (35‰) does not explain all of the variance in δD_alk (84‰). The apparent fractionation of hydrogen isotopes between n-alkanes and precipitation (ε_alk/p) is significantly correlated with variables related to aridity: relative humidity, rainfall amount, and aridity index (defined as the ratio of average precipitation to average potential evapotranspiration). This result demonstrates the important control of aridity on δD_alk, which may result from the increasing soil evaporation and plant transpiration, as well as decreasing biosynthetic fractionation, in arid climates. We compiled published δD_alk data from surface lake/soil sediments in China, and found that aridity effects are pronounced in regions with mean annual precipitation (MAP) < 800 mm. Therefore, we suggest that soil δD_alk reflects precipitation δD modified by aridity, with a greater degree of modification in arid environments (e.g., MAP < 800 mm). Future work to quantitatively determine the effects of aridity on δD_alk is needed to improve the reliability of the application of δD_alk in paleoenvironmental studies.

22756. 题目: Molecular characteristics of microbially mediated transformations of Synechococcus ‐derived dissolved organic matter as revealed by incubation experiments
文章编号: N19050312
期刊: Environmental Microbiology
作者: Qiang Zheng, Qi Chen, Ruanhong Cai, Chen He, Weidong Guo, Yu Wang, Quan Shi, Chang Chen, Nianzhi Jiao
更新时间: 2019-05-03
摘要: In this study, we investigated the microbially‐mediated transformation of labile Synechococcus‐derived DOM to RDOM using a 60‐day experimental incubation system. Three phases of TOC degradation activity (I, II, and III) were observed following addition of Synechococcus‐derived DOM. The phases were characterized by organic carbon consumption rates of 8.77, 1.26, and 0.16 μmol L−1 day−1, respectively. Excitation emission matrix analysis revealed the presence of three FDOM components including tyrosine‐like, fulvic acid‐like, and humic‐like molecules. The three components also exhibited differing biological availabilities that could be considered as labile DOM (LDOM), semi‐labile DOM (SLDOM), and RDOM, respectively. DOM molecular composition was also evaluated using FT‐ICR MS. Based on differing biological turnover rates and normalized intensity values, a total of 1,704 formulas were identified as candidate LDOM, SLDOM, and RDOM molecules. Microbial transformation of LDOM to RDOM tended to proceed from high to low molecular weight, as well as from molecules with high to low double bond equivalent (DBE) values. Relatively higher aromaticity was observed in the formulas of RDOM molecules relative to those of LDOM molecules. FDOM components provide valuable proxy information to investigate variation in the bioavailability of DOM. These results suggest that coordinating fluorescence spectroscopy and FT‐ICR MS of DOM, as conducted here, is an effective strategy to identify and characterize LDOM, SLDOM, and RDOM molecules in incubation experiments emulating natural systems. The results described here provide greater insight into the metabolism of phytoplankton photosynthate by heterotrophic bacteria in marine environments.

22757. 题目: Suspended matter and associated contaminants in Danish streams: a national analysis
文章编号: N19050311
期刊: Journal of Soils and Sediments
作者: Hans Thodsen, Jes Jessen Rasmussen, Brian Kronvang, Hans Estrup Andersen, Anders Nielsen, Søren Erik Larsen
更新时间: 2019-05-03
摘要: Purpose: Suspended matter (SM) in streams is usually considered of minor importance in Danish environmental management. However, SM has some ecological effects as it may (1) clog fish spawning grounds and (2) act as an important agent for transport and exposure of biota to chemical substances, such as phosphorus and toxic inorganic (e.g. heavy metals) and organic (e.g. pesticides) substances. Materials and methods: A large national data set of > 100,000 water samples analysed for SM and loss on ignition was investigated for spatial concentration patterns, sediment yields and temporal trends. Moreover, the importance of SM as a transport agent for phosphorus and heavy metals in streams was investigated through a correlation analysis. Results and discussion: The mean suspended matter concentration (SMC) (including organic matter) amounted to 12 mg l⁻¹, with an organic content of 4.9 mg l⁻¹ (41%). A clear difference in SMC temporal trends over the sampling period was found between geographical regions. Sediment yields were calculated for all major catchments revealing low sediment yields (1–15 t km⁻² year⁻¹) compared to neighbouring countries and showed clear geographical patterns. Statistically significant relationships were established between SMCs, suspended sediment concentrations (SSCs) (excluding organic matter) and organic matter concentrations (OMCs) and particulate phosphorus (PP) concentrations, and again spatial patterns appeared. However, it was clearly shown that SMC/SSC/OMC could not be used as a robust, nationwide, indicator for PP concentrations. Analyses of the relationship between SMC and particle-bound heavy metal concentrations generally revealed weak correlations except for Pb and Ni (median R² > 0.3). Conclusions: Relatively low SM concentrations and sediment yields were found. SM is, in some geographical regions, an important transport agent for PP. Clear geographical patterns occurred in the relationships between SMC/SSC/OMC and both river water discharge and PP, as well as for sediment yields and for temporal trends in SMC.

22758. 题目: Influence of biochar amendment and foliar application of iron oxide nanoparticles on growth, photosynthesis, and cadmium accumulation in rice biomass
文章编号: N19050310
期刊: Journal of Soils and Sediments
作者: Muhammad Rizwan, Shamaila Noureen, Shafaqat Ali, Sarwat Anwar, Muhammad Zia ur Rehman, Muhammad Farooq Qayyum, Azhar Hussain
更新时间: 2019-05-03
摘要: Purpose: The majority studies used the biochar or nanoparticles alone in metal-contaminated soils while less is known about the combined use of these amendments in metal-contaminated soils. We aimed to explore the efficiency of iron oxide nanoparticles (Fe NPs) and biochar on cadmium (Cd) uptake in rice in pot trial. Materials and methods: An experiment was performed under ambient environmental conditions in a Cd-contaminated soil with and without biochar addition (1.0% w/w), and different Fe NP concentrations (0, 10, 20, 30 mg/L) were foliar sprayed at different time intervals (at 3rd, 4th, and 5th weeks of nursery transplantation in the pots) during the plant growth. After harvesting, rice growth, photosynthesis, Cd and Fe contents in rice tissues, and soil bioavailable Cd and soil pH were measured. Results and discussion: Iron NPs enhanced the dry weights of rice tissues, chlorophyll concentrations, and gas exchange characteristics and the impact of NPs was further increased when the biochar was applied along with NPs. Iron NPs significantly decreased the intake of Cd in rice shoots by 31 and 42% and in rice roots by 26 and 39% with the foliar spray of Fe NPs (30 mg/L) without and with biochar, respectively. Foliar spray of Fe NPs reduced the total Cd accumulation by shoots, whereas the total Cd accumulation in the roots increased. The co-presence of Fe NPs and Cd enhanced the Fe concentrations in shoots of rice by 52 and 33% and in roots of rice by 32 and 21% when 30 mg/L Fe NPs were supplied with and without biochar, respectively. The effects of Fe NPs were higher with biochar application than without biochar except Fe concentrations in rice seedlings where the opposite trend was observed. Conclusions: The increase in biomass, Fe concentrations in tissues, and decrease in Cd levels in plants clearly demonstrate that Fe NPs + biochar could be a promising technique for the utilization of Cd-contaminated soils in the future.

22759. 题目: Biochar addition increases subsurface soil microbial biomass but has limited effects on soil CO₂ emissions in subtropical moso bamboo plantations
文章编号: N19050309
期刊: Applied Soil Ecology
作者: Xiaogai Ge, Yonghui Cao, Benzhi Zhou, Xiaoming Wang, Zhenya Yang, Mai-He Li
更新时间: 2019-05-03
摘要: Biochar addition affects soil conditions and soil microorganisms, and it may reduce soil CO₂ emissions. However, knowledge on how biochar addition induces the changes in soil microbial communities with soil depth and time and affects soil respiration is limited in forest ecosystems. We investigated the effects of biochar addition on soil respiration rate and its sensitivity to soil temperature and microbial community composition in moso bamboo (Phyllostachys eduis) plantations in subtropical China for two years. We set up four treatments of biochar addition onto the soil surface of the plantations with the level of 0 (control, CK), 5 (low biochar, LB), 10 (medium biochar, MB), or 20 t biochar ha⁻¹ (high biochar, HB) in April 2014. Biochar addition significantly improved soil moisture at 5 cm soil depth but did not affect soil temperature. Microbial biomass increased significantly with biochar addition at 10–20 cm soil depth but showed no response in the 0–10 cm depth soil layer. Compared to CK, biochar addition significantly affected the mean soil respiration rate during the two–year experiment, but the difference between CK and biochar treatments decreased both with time following biochar addition and with increasing biochar dosage. Annual cumulative soil respiration was significantly and positively correlated with the biomass of total PLFAs, gram-negative bacteria, bacteria, and arbuscular mycorrhizal fungi (P < 0.05) at 0–10 cm soil depth but not at 10–20 cm. Overall, only LB significant decreased the total CO₂ emissions. Our results suggest that lower dosage additions of biochar have a positive effect in reducing total CO₂ emissions and promote soil organic carbon sequestration in bamboo forests in subtropical China.

22760. 题目: Seasonal changes in labile organic matter as a function of environmental factors in a relict permafrost region on the Qinghai-Tibetan Plateau
文章编号: N19050308
期刊: CATENA
作者: Guimin Liu, Xiaolan Zhang, Tonghua Wu, Xiaoli Wu, Joseph M. Smoak, Xinxing Li, Genghao Ji, Haiyan Xu, Xiaoliang Ma, Hongqin Li, Guangyang Yue, Yongjian Ding, Lin Zhao, Xiaodong Wu
更新时间: 2019-05-03
摘要: Labile organic matter plays an important role in permafrost carbon cycling, however, little is known about the effects of permafrost on labile organic matter dynamics. Here, we examined seasonal changes in the labile organic matter including light fraction carbon (LFC), water extractable organic carbon (WEOC), microbial biomass carbon (MBC) and nitrogen (MBN) contents in a relict permafrost region on the eastern edge of the Qinghai-Tibetan Plateau (QTP), China. We selected three different areas including permafrost, boundary, and seasonally frozen ground area. The results showed that seasonal changes in labile organic matter were not the result of soil heterogeneity. Among all three areas, depth strongly correlated with labile organic matter content. LFC was significantly associated with the soil organic carbon (SOC) content. The MBC contents, which were the lowest in permafrost area but highest in seasonally frozen ground area, were strongly affected by temperature. Multiple linear regression models showed that temperature was a significant predictor for labile organic matter in the permafrost area, but the effects of temperature were weaker in the boundary and seasonally frozen ground areas. Our results suggested that permafrost degradation could decrease production but increase decomposition rates of labile organic matter in permafrost regions, and this process should be taken into consideration in permafrost carbon cycle models.