Can pollution bias peatland paleoclimate reconstruction?     

Richard J. Payne  Edward A.D. Mitchell  Hung Nguyen-Viet  Daniel Gilbert 《Quaternary Research》2012,78(2):170-173

Peatland testate amoebae are widely used to reconstruct paleohydrological/climatic changes, but many species are also known to respond to pollutants. Peatlands around the world have been exposed to anthropogenic and intermittent natural pollution through the late Holocene. This raises the question: can pollution lead to changes in the testate amoeba paleoecological record that could be erroneously interpreted as a climatic change? To address this issue we applied testate amoeba transfer functions to the results of experiments adding pollutants (N, P, S, Pb, O₃) to peatlands and similar ecosystems. We found a significant effect in only one case, an experiment in which N and P were added, suggesting that pollution-induced biases are limited. However, we caution researchers to be aware of this possibility when interpreting paleoecological records. Studies characterising the paleoecological response to pollution allow pollution impacts to be tracked and distinguished from climate change.  相似文献   

Optimization of novel hyperthermostable β amylase production by Bacillus subtilis DJ5 using solid agroresidual substrates     

A. Poddar  S. C. Jana 《International Journal of Environmental Science and Technology》2014,11(4):1127-1134

Eight different low cost starchy agroresidues namely Barley (B), Wheat bran (WB), Sattu (S), Rice powder (RP), Corn flour (CF), Rice husk (RH), Yellow peas split (YPS) and arrowroot (A) were used for solid culturing of Bacillus subtilis DJ5 for production of novel hyperthermostable β amylase. Various process parameters like initial moisture content, inoculum load, medium pH and incubation temperature affecting enzyme production were optimized to ensure maximum enzyme yield. Only 10 % inoculums load and medium pH of 6.9 was found sufficient to achieve maximum enzyme production in all substrates in a decreasing order, B > WB > S > RP > CF > RH > YPS > A. Optimum β amylase production was highly dependent on initial moisture content of substrate as observed from varying requirement of moisture for different substrates. Only 50 % moisture was sufficient for maximum enzyme production of 84.29 U/gdm in CF. For B, RH, YPS, and A 60 % initial moisture resulted in higher production of 120.34, 35.19, 26.59, and 21.58 U/gdm, respectively, at 37 °C. However, for S and RP higher (70 %) moisture content allowed 113.4 and 85.56 U/gdm enzyme production, respectively. Under optimized conditions, maximum β amylase production was observed after 25 h for A, YPS, RH, RP; 41 h for B, WB, CF, and 45 h for S.  相似文献   

Fe‐Mn systematics of type IIA chondrules in unequilibrated CO,CR, and ordinary chondrites     

Jana BERLIN  Rhian H. JONES  Adrian J. BREARLEY 《Meteoritics & planetary science》2011,46(4):513-533

Abstract– We have examined Fe/Mn systematics of 34 type IIA chondrules in eight highly unequilibrated CO, CR, and ordinary chondrites using new data from this study and prior studies from our laboratory. Olivine grains from type IIA chondrules in CO chondrites and unequilibrated ordinary chondrites (UOC) have significantly different Fe/Mn ratios, with mean molar Fe/Mn = 99 and 44, respectively. Olivine analyses from both these chondrite groups show well‐defined trends in Mn versus Fe (afu) and molar Fe/Mn versus Fe/Mg diagrams. In general, type IIA chondrules in CR chondrites have properties intermediate between those in UOC and CO chondrites. In most UOC and CR type IIA chondrules, the Fe/Mn ratio of olivine decreases during crystallization, whereas in CO chondrites the Fe/Mn ratio does not appear to change. It is difficult to interpret the observed Fe/Mn trends in terms of differing moderately volatile element depletions inherited from precursor materials. Instead, we suggest that significant differences in the abundances of silicates and sulfides ± metals in the precursor material, as well as open‐system behavior during chondrule formation, were responsible for establishing the different Fe/Mn trends. Using Fe‐Mn‐Mg systematics, we are able to identify relict grains in type IIA chondrules, which could be derived from previous generations of chondrules, including chondrules from other chondrite groups, and possibly chondritic reservoirs that have not been sampled previously.  相似文献   

The COVID-19 pandemic and global environmental change: Emerging research needs     

Robert Barouki  Manolis Kogevinas  Karine Audouze  Kristine Belesova  Ake Bergman  Linda Birnbaum  Sandra Boekhold  Sebastien Denys  Celine Desseille  Elina Drakvik  Howard Frumkin  Jeanne Garric  Delphine Destoumieux-Garzon  Andrew Haines  Anke Huss  Genon Jensen  Spyros Karakitsios  Jana Klanova  Iida-Maria Koskela  Francine Laden  Paolo Vineis 《Chemie der Erde / Geochemistry》2010

The outbreak of COVID-19 raised numerous questions on the interactions between the occurrence of new infections, the environment, climate and health. The European Union requested the H2020 HERA project which aims at setting priorities in research on environment, climate and health, to identify relevant research needs regarding Covid-19. The emergence and spread of SARS-CoV-2 appears to be related to urbanization, habitat destruction, live animal trade, intensive livestock farming and global travel. The contribution of climate and air pollution requires additional studies. Importantly, the severity of COVID-19 depends on the interactions between the viral infection, ageing and chronic diseases such as metabolic, respiratory and cardiovascular diseases and obesity which are themselves influenced by environmental stressors. The mechanisms of these interactions deserve additional scrutiny. Both the pandemic and the social response to the disease have elicited an array of behavioural and societal changes that may remain long after the pandemic and that may have long term health effects including on mental health. Recovery plans are currently being discussed or implemented and the environmental and health impacts of those plans are not clearly foreseen. Clearly, COVID-19 will have a long-lasting impact on the environmental health field and will open new research perspectives and policy needs.  相似文献   

Preparation and characterization of antibacterial silver/vermiculites and silver/montmorillonites   总被引：1，自引：0，他引：1  

Marta Valášková  Marianna Hundáková  Jana Seidlerová  Erich Pazdziora  Martin He?mánek  David Rafaja 《Geochimica et cosmochimica acta》2010,74(22):6287-6300

The reason for the preparation and characterization of the novel antibacterial silver/vermiculites (Ag/V) together with the silver/montmorillonites (Ag/M) was that the information on the vermiculite structure change and stability of Ag/V in water as well as its effect on bacteria are sporadic. The vermiculite (V), (Si_3.02Al_0.98)^IV (Mg_2.27Al_0.12Ti_0.07)^VI O₁₀(OH)₂ Ca_0.09Na_0.21K_0.50 from West China and montmorillonite (M), (Si_3.96Al_0.04)^IV (Al_1.20Mg_0.42Ti_0.02)^VI O₁₀ (OH)₂Ca_0.15Na_0.14K_0.08 from Ivan?ice (Czech Republic), fraction <0.4 μm were the starting clay materials for sample preparation. The samples V1 and M1 were prepared via reaction of the V and M with the 0.01 mol L⁻¹ AgNO₃ aqueous solution. The samples V2 and M2 were treated with the aqueous solution of AgNO₃ for two times. The cation exchange and reduced metallic silver on M1 and V1 evoked the specific surface area (SSA) diminution, the mean particle-size diameter extension and appearance of micropores with radius (<0.4 nm). Repeated silver cation exchange in M2 and V2 reduced particle size, increased slightly SSA and micropores with radius of 0.4-0.5 nm. Samples Ag/V and Ag/M showed higher content of pores with radius 0.5-1.0 nm than original V and M. The Ag concentration was found higher in Ag/V than in Ag/M and higher in repeatedly treated samples: 0.9 wt.% Ag in V1, 1.4 wt.% Ag in V2, 0.6 wt.% Ag in M1 and 1.0 wt.% Ag in M2. Vermiculite structure consisting of the hydrated interstratified phases and the mica-like phase changed to the cation-one-zero layer hydrate interstratification structure in V1 and to the random of two-one layer hydrate interstratifications in V2. Infrared and Mössbauer spectroscopy revealed no changes in the structure of the clay minerals that could be related directly to the sorption and crystallization of silver. Transmission electron microscopy showed that the silver nanoparticles size distribution was much narrower for the samples Ag/M than for Ag/V. The mean size of the Ag particles was between 40 and 50 nm. Although the Ag nanoparticles did not adhere sufficiently at the clay minerals surface and migrated moderately into water, all samples under study were approved to be effective inhibitors of the bacterial growth persisting for the whole testing period of 6 days. Silver/vermiculite was antimicrobial more efficient against Klebsiella pneumoniae and Pseudomonas aeruginosa than silver/montmorillonite.  相似文献   

A thermomechanical model of ice flow in West Antarctica   总被引：5，自引：2，他引：3  

A. J. Payne 《Climate Dynamics》1999,15(2):115-125

 This study uses a three-dimensional thermo-mechanical model to investigate the internal flow dynamics of the West Antarctic Ice Sheet (WAIS). The model allows ice thickness, flow and temperature to interact freely. Its domain is prescribed as that of the present-day grounded WAIS. Realistic present-day climatic and topographical boundary conditions are employed. The analysis of a series of experiments pays particular attention to the location and dynamics of concentrations of ice flow (ice streams). Underlying topographic troughs are crucial in determining the strength and location of these concentrations of flow. The flow pattern generated by subglacial troughs is made more distinct by the inclusion of ice flow/temperature coupling. The inclusion of sliding leads to the generation of limit cycles in the ice flow. They are concentrated around the present-day ice streams B and C of the Siple Coast and have a period of 5 to 10 ky. There appears to be competition between several preferred ice flow pathways in this area. The two end members of the flow regime are a strong ice stream C with a weakened ice stream A/B complex, and strong ice streams A and B with a dormant ice stream C. Ice streams appear to require ice discharges above a certain threshold in order to maintain frictional heat generation and fast flow. Individual ice streams can therefore interact through changes in catchment-area size: a reduction in catchment area reduces the volume of ice entering a stream and can cause stagnation as the amount of frictional heating falls. Received: 22 July 1997/Accepted: 27 July 1998  相似文献   

Development of a unified oil droplet size distribution model with application to surface breaking waves and subsea blowout releases considering dispersant effects     

Zhengkai Li  Malcolm Spaulding  Deborah French McCay  Deborah Crowley  James R. Payne 《Marine pollution bulletin》2017,114(1):247-257

An oil droplet size model was developed for a variety of turbulent conditions based on non-dimensional analysis of disruptive and restorative forces, which is applicable to oil droplet formation under both surface breaking-wave and subsurface-blowout conditions, with or without dispersant application. This new model was calibrated and successfully validated with droplet size data obtained from controlled laboratory studies of dispersant-treated and non-treated oil in subsea dispersant tank tests and field surveys, including the Deep Spill experimental release and the Deepwater Horizon blowout oil spill. This model is an advancement over prior models, as it explicitly addresses the effects of the dispersed phase viscosity, resulting from dispersant application and constrains the maximum stable droplet size based on Rayleigh-Taylor instability that is invoked for a release from a large aperture.  相似文献   

A naturally efficient numerical technique for porous convection stability with non‐trivial boundary conditions     

L. E. Payne  B. Straughan 《国际地质力学数值与分析法杂志》2000,24(10):815-836

A highly efficient numerical technique is presented for solving eigenvalue problems which arise in complicated convection — instability studies in porous media. The differential equations are written as a system of ‘natural’ variables which are suggested by the way the boundary conditions arise. The method easily gives high resolution in boundary layers, yields all the eigenvalues and eigenfunctions, deals with complex coefficients, and can handle spatially dependent coefficients in a very efficient manner. The numerical technique is motivated by the practical problem of salinization in porous sands in arid zones as is beautifully modelled by Gilman and Bear. Since the salinization study of Gilman and Bear is a prototype for the field of convective motion in unsaturated porous soils and this field is one which is increasingly occupying geotechnical attention, we believe the numerical method presented here has much potential. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

The rockwall in rockwall,texas: A study of unusual natural magnetic effects in geoarcheological surveys produced by mineral oxidation     

Brooks B. Ellwood  Jana Payne  Gary J. Long 《Geoarchaeology》1989,4(2):103-118

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