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Improved speciation of dissolved organic nitrogen in natural waters: amide hydrolysis with fluorescence derivatization

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Journal of environmental sciences 2008年第10期20卷 1273-1280页

作者： Ryan L.Fimmen Tamara D.Trouts Daniel D.Richter Jr. Dharni Vasudevan school of earth sciences The Ohio State University 125 S.Oval MallColumbus OH 43210 USA.Nicholas School of the Environment and Earth Sciences Duke University Durham NC 27708 USA school of earth sciences The Ohio State University 125 S.Oval MallColumbus OH 43210 USA nicholas school of the environment and earth sciences Duke UniversityDurham NC 27708 USA. nicholas school of the environment and earth sciences Duke UniversityDurham NC 27708 USA.Department of Chemistry Bowdoin CollegeBrunswick ME 04011 USA

The objective of this study was to improve primary-amine nitrogen (1°-N) quantification in dissolved organic matter (DOM) originating from natural waters where inorganic forms of N, which may cause analytical interference, are commonly encountered. Efforts were targeted at elucidating organic-N structural criteria influencing the response of organic amines to known colorimetric and fluorescent reagents and exploring the use of divalent metal-assisted amide hydrolysis in combination with fluorescence analyse...

关键词： dissolved organic matter/nitrogen (DOM/DON) o-phthaldialdehyde fluorescamine ninhydrin amino acids amide hydrolysis peptides

Sorption of tylosin and sulfamethazine on solid humic acid

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Journal of environmental sciences 2016年第5期28卷 208-215页

作者： Xuetao Guo Bei Tu Jianhua Ge Chen Yang Xiaomei Song Zhi Dang school of earth and environment Anhui University of Science and Technology College of environment and Energy South China University of Technology

Tylosin（TYL） and sulfamethazine（SMT） are ionizable and polar antimicrobial compounds,which have seeped into the environment in substantial amounts via fertilizing land with manure or sewage. Sorption of TYL and SMT onto humic acid（HA） may affect their environmental fate. In this study, the sorption of TYL and SMT on HA at different conditions（pH, ionic strength） was investigated. All sorption isotherms fitted well to the Henry and Freundlich models and they were highly nonlinear with values of n between 0.5 and 0.8, which suggested that the HA had high heterogeneity. The sorption of TYL and SMT on HA decreased with increasing p H（2.0–7.5）, implying that the primary sorption mechanism could be due to cation exchange interactions between TYL~＋/SMT~＋ species and the functional groups of *** ionic strength resulted in a considerable reduction in the K_d values of TYL and SMT,hinting that interactions between H bonds and π–π EDA might be an important factor in the sorption of TYL and SMT on HA. Results of Fourier transform infrared（FT-IR） and ~13C-nuclear magnetic resonance（NMR） analysis further demonstrated that carboxyl groups and O-alkyl structures in the HA could interact with TYL and SMT via ionic interactions and H bonds,respectively. Overall, this work gives new insights into the mechanisms of sorption of TYL and SMT on HA and hence aids us in assessing the environmental risk of TYL and SMT under diverse conditions.

关键词： Sorption Antibiotics Humic acid Cation exchange

Metamorphic fluxes of water and carbon in rivers of the eastern Qinghai-Tibetan Plateau

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science China earth sciences 2022年第4期65卷 652-661页

作者： Jun ZHONG Siliang LI Zheng LI Xuetao ZHU Yuanbi YI Tingting MA Sheng XU Congqiang LIU Institute of Surface-earth System science School of Earth System ScienceTianjin UniversityTianjin 300072China school of environment Tsinghua UniversityBeijing 100084China

Geothermal activities are common in active orogenic zones and play an important role in surface-earth geochemical *** we analyzed the water chemical compositions,stable and radioactive carbon isotopes of dissolved inorganic carbon(δ^(13)CDICandΔ^(14)CDIC)of hot springs and large rivers in the eastern Qinghai-Tibetan Plateau(QTP).The hot springs had major ions’concentrations varying in a wide range,and most hot springs’alkalinities resulted from high-temperature silicate *** observed hot springs’waters were affected by the mixing of metamorphic fluids and surface waters,which altered the water chemistry andΔ^(14)CDICof the hot *** the observedΔ^(14)CDICin hot springs was much higher than the theoreticalΔ^(14)CDICin metamorphic fluids(i.e.,-1000‰),we used an isotopic mass balance approach(i.e.,Δ^(14)CDIC)to quantify the contribution of surface waters to the hot *** the ions of metamorphic fluids were calibrated byΔ^(14)CDIC,the metamorphic water fluxes were calculated by the chemical mass balance approach of Ge/Si ratios,using the Monte-Carlo *** found that the proportion of metamorphic water fluxes to the river discharge ranged from 0.17%for the Yellow River to 0.52%for the Jinsha River,and it would be much higher in some *** horizontal metamorphic contributions of alkalinity to the large rivers ranged from 0.87%to 3.96%in eastern QTP,and the vertical metamorphic carbon outgassing would be much *** metamorphic fluids fluxes estimated in this study were much lower than previous estimations extrapolated from small Himalayan rivers,and thus we thought that the previous estimations of metamorphic carbon fluxes in QTP were likely *** propose that systematic studies are needed to be conducted to constrain the metamorphic carbon flux in *** study shed light on the release of metamorphic carbon in the orogenic zone,placing limits on the results of orogenic forcing on chemical weatherabili

关键词： Geothermal activities Δ^(14)CDIC Ge/Si ratio Qinghai-Tibetan Plateau Metamorphic carbon

Analysis of Landsat 8 detection of the interannual variability of grassland curing in Greater Melbourne,Australia

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International Journal of Digital earth 2020年第11期13卷 1321-1338页

作者： Sike Li school of earth Atmosphere and EnvironmentFaculty of ScienceMonash UniversityMelbourneAustralia

As one of the main components of Grassland Fire Danger Index,grassland curing degree provides crucial information for determining grassland fire *** estimates of grassland curing are critical for determining grassland fire *** research focuses on the use of Landsat 8 to estimate grassland *** demonstrate that Landsat 8 observations can be used to estimate curing percentages as assessed by visual and ground sampling *** interannual variability for the Greater Melbourne region using Landsat 8 imagery from 2013 to 2019 is *** differences in curing times and degree are observed for sample sites surrounding Greater Melbourne due to climatic differences across the *** is regarded as an essential variable affecting curing degree and this relationship is evident for all five sample *** 8 curing results are compared to both visual observations and destructive sampling,the most accurate method,for accuracy *** 95%confidence level,Landsat 8 estimations are no different from destructive ground sampling ***,this study validates the use of Landsat 8 data as an effective and accurate way for grassland curing monitoring.

关键词： Grassland curing remote sensing grassland fires Melbourne interannual variability

Inter-satellite variability of grassland curing maps produced by different satellite sensors-Victoria,Australia

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International Journal of Digital earth 2021年第7期14卷 899-920页

作者： Sike Li school of earth Atmosphere and EnvironmentFaculty of ScienceMonash UniversityClaytonAustralia

Grassland fires are a serious problem in Victoria,Australia due to large quantity of dry *** curing degree(GCD)measures the dryness of the grass and is an important factor for assessing grassland fire *** curing maps(GCMs)display the spatial distribution of GCDs,but the quality of GCMs varies depending on the spatial resolution of the observing satellite remote sensing *** higher the spatial resolution,the finer the GCD details and more spatial variations the GCM can *** this study,GCD calculation algorithm named MapVictoria based on MODIS data is tested for Landsat 8 Sentinel 2;GCMs generated from these three satellites are contrasted by their GCD differences,defined here as inter-satellite variability(ISV).ISV is used to identify areas where higher resolution satellite GCMs should be *** show that spatial resolution difference(ΔSR),seasonality and geographical locations affect the magnitude of the *** on these findings,this paper provides recommendations to decision makers on where and when to use which satellite for grassland observations.

关键词： Grassland curing remote sensing grassland fires Australia variability

Mechanism and kinetics of hydrothermal replacement of magnetite by hematite

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Geoscience Frontiers 2019年第1期10卷 29-41页

作者： Jing Zhao Joel Brugger Allan Pring Chemical and Physical science College of Science and Engineering Flinders University school of earth Atmosphere and the Environment Monash University

The replacement of magnetite by hematite was studied through a series of experiments under mild hydrothermal conditions(140 -220℃, vapour saturated pressures) to quantify the kinetics of the transformation and the relative effects of redox and non-redox processes on the transformation. The results indicate that oxygen is not an essential factor in the replacement reaction of magnetite by hematite, but the addition of excess oxidant does trigger the oxidation reaction, and increases the kinetics of the transformation. However, even under high O_2(aq) environments, some of the replacement still occurred via Fe^(2+) leaching from magnetite. The kinetics of the replacement reaction depends upon temperature and solution parameters such as pH and the concentrations of ligands, all of which are factors that control the solubility of magnetite and affect the transport of Fe^(2+) (and the oxidant) to and from the reaction front. Reaction rates are fast at ~200℃, and in nature transport properties of Fe and,in the case of the redox-controlled replacement, the oxidant will be the rate-limiting control on the reaction progress. Using an Avrami treatment of the kinetic data and the Arrhenius equation, the activation energy for the transformation under non-redox conditions was calculated to be 26 ± 6 kJ mol^(-1).This value is in agreement with the reported activation energy for the dissolution of magnetite, which is the rate-limiting process for the transformation under non-redox conditions.

关键词： Mineral replacement reaction Hematite Magnetite Kinetics Non-redox Redox

Electron Magnetohydrodynamics Magnetic Reconnection Experiment on Keda Linear Magnetized Plasma Device

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Chinese Physics Letters 2019年第1期36卷 40-43页

作者： Feibin Fan Jinlin Xie Qiaofeng Zhang Longlong Sang Weixing Ding CAS Key Laboratory of Geoscience environment School of Earth and Space Sciences University of Science and Technology of China CAS Key Laboratory of Geoscience environment School of Physics University of Science and Technology of China

We conduct an electron magnetohydrodynamics magnetic reconnection experiment with guide-field in our Keda linear magnetized plasma device, in which two pulsed currents with the same direction are conducted in parallel with the axial direction of the main chamber of the device using two long aluminum sticks. After approximately 5μs, an X-type magnetic field line topology is formed at the center of the chamber. With the formation of the X-type topology of magnetic field lines, we can also find the rapid increase of the current and ratio of the common flux to the private flux in this area. Additionally, a reduction in the plasma density and the plasma density concentration along one pair of separatrices can also be found.

关键词： Electron magnetohydrodynamics Magnetic Reconnection Experiment Keda Linear Magnetized Plasma Device

Flow dynamics and sediment transport in vegetated rivers:A review

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Journal of Hydrodynamics 2021年第3期33卷 400-420页

作者： Wen-xin Huai Shuolin Li Gabriel G.Katul Meng-yang Liu Zhong-hua Yang State Key Laboratory of Water Resources and Hydropower Engineering science Wuhan UniversityWuhan430072China Department of Civil and environmental Engineering Duke UniversityDurhamNCUSA nicholas school of the environment and earth science Duke UniversityDurhamNCUSA

The significance of riparian vegetation on river flow and material transport is not in *** laws,sediment erosion and deposition,and element cycling must all be adjusted from their canonical rough-wall boundary layer to accommodate the presence of aquatic *** turn,the growth and colonization of riparian vegetation are affected by fluvial processes and river morphology on longer time *** interactions and feedbacks at multiple time scales are now drawing significant attention within the research community given their relevance to river *** this reason,a review summarizing methods,general laws,qualitative cognition,and quantitative models regarding the interplay between aquatic plants,flow dynamics,and sediment transport in vegetated rivers is in ***,pitfalls,knowledge gaps,and daunting challenges to the current state of knowledge are also *** a multidisciplinary research topic,a future research agenda and opportunities pertinent to river management and enhancement of ecosystem services are also highlighted.

关键词： Canopy flow river morphology riparian vegetation sediment transport

Water-Extractable Carbon Pools and Microbial Biomass Carbon in Sodic Water-Irrigated Soils Amended with Gypsum and Organic Manures

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Pedosphere 2013年第1期23卷 88-97页

作者： O.P.CHOUDHARY J.K.GILL BIJAY-SINGH Department of Soil science Punjab Agricultural University school of earth and environment University of Western Australia

Microbial biomass carbon (MBC), a small fraction of soil organic matter, has a rapid turnover rate and is a reservoir of labile nutrients. The water-extractable carbon pools provide a fairly good estimate of labile C present in soil and can be easily quantified. Changes in soil MBC and water-extractable organic carbon pools were studied in a 14-year long-term experiment in plots of rice-wheat rotation irrigated with canal water (CW), sodic water (SW, 10-12.5 mmol c L-1 residual sodium carbonate), and SW amended with gypsum with or without application of organic amendments including farmyard manure (FYM), green manure (GM), and wheat straw (WS). Irrigation with SW increased soil exchangeable sodium percentage by more than 13 times compared to irrigation with CW. Sodic water irrigation significantly decreased hot water-extractable organic carbon (HWOC) from 330 to 286 mg kg-1 soil and cold water-extractable organic carbon (CWOC) from 53 to 22 mg kg-1 soil in the top 0-7.5 cm soil layer. In the lower soil layer (7.5-15 cm), reduction in HWOC was not significant. Application of gypsum alone resulted in a decrease in HWOC in the SW plots, whereas an increase was recorded in the SW plots with application of both gypsum and organic amendments in both the soil layers. Nevertheless, application of gypsum and organic amendments increased the mean CWOC as compared with application of gypsum alone. CWOC was significantly correlated with MBC but did not truly reflect the changes in MBC in the treatments with gypsum and organic amendments applied. For the treatments without organic amendments, HWOC was negatively correlated with MBC (r = 0.57*) in the 0-7.5 cm soil layer, whereas for the treatments with organic amendments, both were positively correlated. Irrigation with SW significantly reduced the rice yield by 3 t ha-1 and the yield of rice and wheat by 5 t ha-1 as compared to irrigation with canal water. Application of amendments significantly increased rice and wheat yields.

关键词： cold water exchangeable sodium percentage hot water organic carbon yield