Comparative effects of herbicides on photosynthesis and growth of tropical estuarine microalgae   总被引：1，自引：0，他引：1  

Magnusson M  Heimann K  Negri AP 《Marine pollution bulletin》2008,56(9):1545-1552

Pulse amplitude modulation (PAM) fluorometry is ideally suited to measure the sub-lethal impacts of photosystem II (PSII)-inhibiting herbicides on microalgae, but key relationships between effective quantum yield [Y(II)] and the traditional endpoints growth rate (mu) and biomass increase are unknown. The effects of three PSII-inhibiting herbicides; diuron, hexazinone and atrazine, were examined on two tropical benthic microalgae; Navicula sp. (Heterokontophyta) and Nephroselmis pyriformis (Chlorophyta). The relationships between Y(II), mu and biomass increase were consistent (r(2)0.90) and linear (1:1), validating the utility of PAM fluorometry as a rapid and reliable technique to measure sub-lethal toxicity thresholds of PSII-inhibiting herbicides in these microalgae. The order of toxicity (EC(50) range) was: diuron (16-33nM)>hexazinone (25-110nM)>atrazine (130-620nm) for both algal species. Growth rate and photosynthesis were affected at diuron concentrations that have been detected in coastal areas of the Great Barrier Reef.  相似文献   

Determination of Rare Earth Elements in Geological Reference Materials: A Comparative Study by INAA and ICP-MS   总被引：3，自引：0，他引：3  

Fung Dai Kin  M. Isabel Prudêncio  M. Ângela Gouveia  Erik Magnusson 《Geostandards and Geoanalytical Research》1999,23(1):47-58

Data was obtained for the rare earth elements (REE) by instrumental neutron activation analysis (INAA) and inductively coupled plasma-mass spectrometry (ICP-MS) in twenty geological reference materials. In general, the precision obtained by ICP-MS is better for the light REE, decreasing with increasing atomic number. This is partly a result of the occurrence of the heavy REE at low concentrations. The precision of the data obtained by INAA is good (5% RSD). The data obtained also showed that for the elements determined by both methods, the accuracy is similar for the light REE and better for the middle and heavy REEs by INAA. Higher uncertainty is achieved by ICP-MS mainly for elements at very low concentrations, occurring at about ten times the chondritic values.  相似文献   

Impact of recycling and lateral sediment input on grain size fining trends—Implications for reconstructing tectonic and climate forcings in ancient sedimentary systems     

Rebekah M. Harries  Linda A. Kirstein  Alex C. Whittaker  Mikael Attal  Ian Main 《Basin Research》2019,31(5):866-891

Grain size trends in basin stratigraphy are thought to preserve a rich record of the climatic and tectonic controls on landscape evolution. Stratigraphic models assume that over geological timescales, the downstream profile of sediment deposition is in dynamic equilibrium with the spatial distribution of tectonic subsidence in the basin, sea level and the flux and calibre of sediment supplied from mountain catchments. Here, we demonstrate that this approach in modelling stratigraphic responses to environmental change is missing a key ingredient: the dynamic geomorphology of the sediment routing system. For three large alluvial fans in the Iglesia basin, Argentine Andes we measured the grain size of modern river sediment from fan apex to toe and characterise the spatial distribution of differential subsidence for each fan by constructing a 3D model of basin stratigraphy from seismic data. We find, using a self‐similar grain size fining model, that the profile of grain size fining on all three fans cannot be reproduced given the subsidence profile measured and for any sediment supply scenario. However, by adapting the self‐similar model, we demonstrate that the grain size trends on each fan can be effectively reproduced when sediment is not only sourced from a single catchment at the apex of the system, but also laterally, from tributary catchments and through fan surface recycling. Without constraint on the dynamic geomorphology of these large alluvial systems, signals of tectonic and climate forcing in grain size data are masked and would be indecipherable in the geological record. This has significant implications for our ability to make sensitive, quantitative reconstructions of external boundary conditions from the sedimentary record.  相似文献   

Modelling Fracture Propagation in Anisotropic Rock Mass     

Baotang Shen  Topias Siren  Mikael Rinne 《Rock Mechanics and Rock Engineering》2015,48(3):1067-1081

  相似文献   

A FEniCS-based programming framework for modeling turbulent flow by the Reynolds-averaged Navier-Stokes equations     

Mikael Mortensen  Hans Petter Langtangen  Garth N. Wells 《Advances in water resources》2011,34(9):1082-1101

Finding an appropriate turbulence model for a given flow case usually calls for extensive experimentation with both models and numerical solution methods. This work presents the design and implementation of a flexible, programmable software framework for assisting with numerical experiments in computational turbulence. The framework targets Reynolds-averaged Navier-Stokes models, discretized by finite element methods. The novel implementation makes use of Python and the FEniCS package, the combination of which leads to compact and reusable code, where model- and solver-specific code resemble closely the mathematical formulation of equations and algorithms. The presented ideas and programming techniques are also applicable to other fields that involve systems of nonlinear partial differential equations. We demonstrate the framework in two applications and investigate the impact of various linearizations on the convergence properties of nonlinear solvers for a Reynolds-averaged Navier-Stokes model.  相似文献   

Carbon capture and storage in developing countries: A comparison of Brazil, South Africa and India     

Mikael Román 《Global Environmental Change》2011,21(2):391-401

The ambition to introduce carbon capture and storage (CCS) technology in developing countries raises particular considerations and challenges, where, most fundamentally, pressing socio-economic needs imply that there are other political priorities than GHG mitigation. This suggests that the interest in, and viability of, large-scale deployment of CCS in developing countries has to be analyzed as a strategic issue in the overall context of national development. But what are then the strategic concerns that may influence developing countries’ decisions to pursue large-scale deployment of CCS technology? The present article takes a first step in answering this question by comparing CCS policies and ongoing activities in Brazil, India and South Africa.  相似文献   

Extreme wave events and sampling variability     

Bitner-Gregersen  Elzbieta M.  Gramstad  Odin  Magnusson  Anne Karin  Malila  Mika Petteri 《Ocean Dynamics》2021,71(1):81-95

Ocean Dynamics - Wave field data are affected not only by the accuracy of instruments recording them but also by sampling variability, an uncertainty due to the limited number of observations. For...  相似文献   

Transneptunian Object Ephemeris Service (TNOEPH)     

Granvik  Mikael  Virtanen  Jenni  Muinonen  Karri  Bowell  Edward  Koehn  Bruce  Tancredi  Gonzalo 《Earth, Moon, and Planets》2003,92(1-4):73-78

We present a web service called TNOEPH ( http://asteroid.lowell.edu/)for ephemeris uncertainty prediction and dynamical classification ofshort-arc trans\-neptunian objects (TNOs). User-supplied observations are transformed to a rigorous sky-plane uncertainty map using the technique of statistical orbital ranging. We show examples of thegrowth of ephemeris uncertainty with time, and give the probabilities ofdifferent dynamical classifications for a few short-arc TNOs.  相似文献   

Variations of the Wake Height over the Bolund Escarpment Measured by a Scanning Lidar     

Julia Lange  Jakob Mann  Nikolas Angelou  Jacob Berg  Mikael Sjöholm  Torben Mikkelsen 《Boundary-Layer Meteorology》2016,159(1):147-159

  相似文献   

Development of oil formation theories and their importance for peak oil     

Mikael Höök  Ugo Bardi  Lianyong Feng  Xiongqi Pang 《Marine and Petroleum Geology》2010

This paper reviews the historical development of both biogenic and non-biogenic petroleum formation. It also examines the recent claim that the so-called “abiotic” oil formation theory undermines the concept of “peak oil,” i.e. the notion that world oil production is destined to reach a maximum that will be followed by an irreversible decline. We show that peak oil is first and foremost a matter of production flows. Consequently, the mechanism of oil formation does not strongly affect depletion. We would need to revise the theory beyond peak oil only for the extreme — and unlikely — hypothesis of abiotic petroleum formation.  相似文献