Kinetic studies of lead(II) uptake by the seagrass Zostera muelleri in water by radiotracing,atomic absorption spectrometry and electrochemical techniques     

Alan M Bond  Julie R Bradbury  Henry A Hudson  John S Garnham  Peter J Hanna  Stanley Strother 《Marine Chemistry》1985,16(1):1-9

Evidence was found that uptake of lead from seawater in both model and natural systems by the leaves of the seagrass Zostera muelleri does occur for live, dead and scraped leaves at all the lead concentrations tested. Positive uptake of lead was measured using the three analytical techniques of radio-tracer, differential pulse anodic stripping voltammetry and atomic absorption spectrometry; similar uptake profiles were obtained for each technique. Profiles always showed an initial rapid uptake phase followed by a gradual transition to a plateau phase at which an approximate equilibrium between lead attached to seagrass and free ionic lead in seawater was reached. The presence of active lead uptake processes was indicated in experiments which attempted to remove lead from leaves by a chelating agent.  相似文献   

User participation and fishery management performance within the pacific fishery management council     

Susan S. Hanna 《Ocean & Coastal Management》1995,28(1-3)

Fish populations have the potential to contribute to the long-term economic and social benefit of humans, but to do so they must be managed in ways which maintain ecological health. There are many ways that management performance can be assessed, but four measures are particularly pertinent to sustainability: equity, stewardship, regulatory resilience, and efficiency. A key factor in management performance is the process by which management tools are developed and implemented. One approach that has been recommended to improve performance is to structure the management process around user participation. The paper analyzes three case studies of user participation in ad hoc processes of Pacific groundfish management: the development of a license limitation program; an inter-gear sablefish allocation; and the development of a sablefish individual quota (IQ) program. The case studies illustrate the role played by participation in contributing to the equity, stewardship, resilience, and efficiency of the management process. The effect of user participation was mixed in the three cases, depending on the history of participation, the structure and process of participation, on resource conditions and on the characteristics of the program under consideration. Participation can contribute positively to fishery management performance when there is a history of collective decision-making, the time line is slow enough to allow a full consideration of the issues, educational possibilities are pursued and the condition of the resource allows equitable compromises.  相似文献   

Quick matching technique to study the relationship between solar radius and luminosity variations     

Sabatino Sofia  Kwing L. Chan 《Solar physics》1982,76(1):145-153

A simple matching technique is developed which allows us to compute the response of the solar envelope to perturbations which occur within the solar convective region, and in timescales of importance to climate. This technique is applied to perturbation of the convective efficiency (-mechanism), and of the non-gas component of the pressure in different regions of the convection zone (-mechanism). The results indicate that while either perturbation affects the solar luminosity, the -mechanism has almost no effect on the solar outer radius, regardless of the affected region, whereas the -mechanism produces radius changes which may be large if the location of perturbation is deep enough.  相似文献   

Solar irradiance modulation by active regions during 1980     

Sabatino Sofia  Ludwig Oster  Kenneth Schatten 《Solar physics》1982,80(1):87-98

The solar irradiance modulation due to active regions during 1980 has been investigated in detail. Specifically, we estimate the uncertainties caused by ground-based data used as input in the modeling effort, and by our currently incomplete knowledge of the proper parameters that describe the angular variation of sunspot and facular contrasts. We conclude that the most significant uncertainties are due to errors in area measurements and, possibly, varying spot and facular brightness. A standard model for later use is derived by a best-fit technique of the currently available ACRIM irradiance data and the predictions of our models with appropriately varied parameters. Finally, we compute the expected irradiance for the entire year of 1980.NRC Senior Research Associate on leave from the Joint Institute for Laboratory Astrophysics and the Astro-Geophysics Department, University of Colorado at Boulder, Colo., U.S.A.  相似文献   

Boundary-layer parameterizations for applied dispersion modeling over urban areas   总被引：3，自引：0，他引：3  

Steven R. Hanna  Joseph C. Chang 《Boundary-Layer Meteorology》1992,58(3):229-259

Many applied dispersion models require the knowledge of boundary-layer parameters such as sensible heat flux,Q _H , friction velocity,u _*, and turbulent energy components, _w and _v . Formulas are suggested for calculating these parameters over a wide variety of types of ground surfaces, based on simple observations of wind speed near the ground and fractional cloud cover, and specification of constants such as roughness length, albedo, and soil moisture availability. Observations ofu _*,Q _H , _w , and _v during field experiments in St. Louis and Indianapolis are used to test the formulas for urban sites. Relative errors of about ±20% in the predictions are seen to occur whenu _*,Q _H , _w , and _v are large. However, when these quantities are small (e.g.,u _* < 0.2 m/s), the errors in the predictions are as large as the mean value of the quantity itself.In addition, it is concluded from studies of available field data and theories that the magnitude of _w is not well-known at elevations above about 100m during the late afternoon and night. Some simple parameterizations for _w . are suggested that are consistent with the observed steady decrease in ground-level concentration in the afternoon and the sudden increase in concentration that can occur a few hours after sunset due to wind shears associated with a low-level jet, for continuous plumes emitted from moderate to tall stacks.  相似文献   

Biological and Geochemical Record of Anthropogenic Impacts in Recent Sediments from Lake Pupuke, Auckland City, New Zealand     

Paul Augustinus  Michael Reid  Sofia Andersson  Yanbin Deng  Mark Horrocks 《Journal of Paleolimnology》2006,35(4):789-805

Frozen sediment cores from Lake Pupuke in Auckland City, New Zealand, contain a high resolution decadal to annual scale record of changing lake paleoenvironments and geochemistry that reflects changing landuse and hydrology in the catchment over the past c. 190 years. A reliable chronology is available from AMS ¹⁴C and ²¹⁰Pb dating of the sediments, with the timing of the older part of the record supported by the first appearance of pollen of introduced Pinus and Plantago lanceolata associated with European settlement of Auckland in the early 1840s. Diatom stratigraphy, sediment elemental and carbon isotope geochemistry reflect changes in sediment sources and lake conditions commensurate with European development of the Lake Pupuke catchment, in particular enhanced algal productivity controlled by the influx of nutrients after c. 1920 AD. Attempts to prevent nuisance algal blooms in 1933, 1934 and 1939 using CuSO₄ addition produced Cu spikes in the sediment that allowed confirmation of the accuracy of the ²¹⁰Pb chronology. Hence, the elemental and isotopic composition of the Lake Pupuke sediments reflect the timing of significant anthropogenic activities, rather than climatic variations, that have occurred within the watershed over the past c. 190 years. The comparison of records of land use change in the catchment with the multi-proxy record of changes in the sediments usually allowed unambiguous identification of the signatures of change and their causes.  相似文献   

Relationships between climatic factors and flower and boll production in Egyptian cotton (Gossypium barbadense)     

Z. M. Sawan  L. I. Hanna  Gh. A. Gad El Karim  W. L McCuistion 《Journal of Arid Environments》2002,52(4):499

Fruiting of cotton plant is determined and influenced by cultivar, climatic conditions, management practices and pests. An understanding of the flowering and boll retention patterns of cotton cultivars can contribute to more efficient and economical crop management. The objective of this investigation was to study the effect of various climatic factors on flower and boll production of Egyptian cotton. This could be used in formulating advanced predictions of the effect of certain climatic conditions on the production of Egyptian cotton. Two uniform field trials, using cotton Gossypium barbadense cv. Giza 75 were carried out in 1992 and 1993 at the Agricultural Research Station, Agricultural Research Center, Ministry of Agriculture, Giza, Egypt, to investigate the relationships between climatic factors, flower and boll production. Climatic factors included maximum and minimum air temperatures along with their difference, evaporation, surface soil temperature (grass temperature or green cover temperature) at 0600 and 1800 h°C⁻¹, sunshine duration, maximum and minimum humidity and wind speed. The effects of climatic factors on flower and boll production were quantified in the absence of water and nutritional deficits and damage effects of insects. Results obtained indicate that evaporation, sunshine duration, humidity, surface soil temperature at 1800 h, and maximum air temperature, were the important climatic factors that significantly affect flower and boll production of Egyptian cotton. Consequently, applying appropriate specific cultural practices that minimize the deleterious effect of these factors will lead to an improvement in cotton yield.  相似文献   

Stone Age settlement and Holocene shore displacement in the Narva‐Luga Klint Bay area,eastern Gulf of Finland     

Alar Rosentau  Merle Muru  Aivar Kriiska  Dmitry A. Subetto  Jüri Vassiljev  Tiit Hang  Dmitry Gerasimov  Kerkko Nordqvist  Anna Ludikova  Lembi Lõugas  Hanna Raig  Kersti Kihno  Raivo Aunap  Nikolay Letyka 《Boreas: An International Journal of Quaternary Research》2013,42(4):912-931

Based on geological and archaeological proxies from NW Russia and NE Estonia and on GIS‐based modelling, shore displacement during the Stone Age in the Narva‐Luga Klint Bay area in the eastern Gulf of Finland was reconstructed. The reconstructed shore displacement curve displays three regressive phases in the Baltic Sea history, interrupted by the rapid Ancylus Lake and Litorina Sea transgressions c. 10.9–10.2 cal. ka BP and c. 8.5–7.3 cal. ka BP, respectively. During the Ancylus transgression the lake level rose 9 m at an average rate of about 13 mm per year, while during the Litorina transgression the sea level rose 8 m at an average rate of about 7 mm per year. The results show that the highest shoreline of Ancylus Lake at an altitude of 8–17 m a.s.l. was formed c. 10.2 cal. ka BP and that of the Litorina Sea at an altitude of 6–14 m a.s.l., c. 7.3 cal. ka BP. The oldest traces of human activity dated to 8.5–7.9 cal. ka BP are associated with the palaeo‐Narva River in the period of low water level in the Baltic basin at the beginning of the Litorina Sea transgression. The coastal settlement associated with the Litorina Sea lagoon, presently represented by 33 Stone Age sites, developed in the area c. 7.1 cal. ka BP and existed there for more than 2000 years. Transformation from the coastal settlement back to the river settlement indicates a change from a fishing‐and‐hunting economy to farming and animal husbandry c. 4.4 cal. ka BP, coinciding with the time of the overgrowing of the lagoon in the Narva‐Luga Klint Bay area.  相似文献   

Comparative assessment of Japan's long-term carbon budget under different effort-sharing principles     

Takeshi Kuramochi  Jusen Asuka  Hanna Fekete  Kentaro Tamura  Niklas Höhne 《Climate Policy》2016,16(8):1029-1047

This article assesses Japan's carbon budgets up to 2100 in the global efforts to achieve the 2?°C target under different effort-sharing approaches based on long-term GHG mitigation scenarios published in 13 studies. The article also presents exemplary emission trajectories for Japan to stay within the calculated budget.

The literature data allow for an in-depth analysis of four effort-sharing categories. For a 450?ppm CO₂e stabilization level, the remaining carbon budgets for 2014–2100 were negative for the effort-sharing category that emphasizes historical responsibility and capability. For the other three, including the reference ‘Cost-effectiveness’ category, which showed the highest budget range among all categories, the calculated remaining budgets (20th and 80th percentile ranges) would run out in 21–29 years if the current emission levels were to continue. A 550?ppm CO₂e stabilization level increases the budgets by 6–17 years-equivalent of the current emissions, depending on the effort-sharing category. Exemplary emissions trajectories staying within the calculated budgets were also analysed for ‘Equality’, ‘Staged’ and ‘Cost-effectiveness’ categories. For a 450?ppm CO₂e stabilization level, Japan's GHG emissions would need to phase out sometime between 2045 and 2080, and the emission reductions in 2030 would be at least 16–29% below 1990 levels even for the most lenient ‘Cost-effectiveness’ category, and 29–36% for the ‘Equality’ category. The start year for accelerated emissions reductions and the emissions convergence level in the long term have major impact on the emissions reduction rates that need to be achieved, particularly in the case of smaller budgets.

Policy relevance

In previous climate mitigation target formulation processes for 2020 and 2030 in Japan, neither equity principles nor long-term management of cumulative GHG emissions was at the centre of discussion. This article quantitatively assesses how much more GHGs Japan can emit by 2100 to achieve the 2?°C target in light of different effort-sharing approaches, and how Japan's GHG emissions can be managed up to 2100. The long-term implications of recent energy policy developments following the Fukushima nuclear disaster for the calculated carbon budgets are also discussed.  相似文献   

Europe adapts to climate change: Comparing National Adaptation Strategies     

G. Robbert Biesbroek  Rob J. Swart  Timothy R. Carter  Caroline Cowan  Thomas Henrichs  Hanna Mela  Michael D. Morecroft  Daniela Rey 《Global Environmental Change》2010,20(3):440-450

For the last two decades, European climate policy has focused almost exclusively on mitigation of climate change. It was only well after the turn of the century, with impacts of climate change increasingly being observed, that adaptation was added to the policy agenda and EU Member States started to develop National Adaptation Strategies (NASs). This paper reviews seven National Adaptation Strategies that were either formally adopted or under development by Member States at the end of 2008. The strategies are analysed under the following six themes. Firstly, the factors motivating and facilitating the development of a national adaptation strategy. Secondly, the scientific and technical support needed for the development and implementation of such a strategy. Thirdly, the role of the strategy in information, communication and awareness-raising of the adaptation issue. Fourthly, new or existing forms of multi-level governance to implement the proposed actions. Fifthly, how the strategy addresses integration and coordination with other policy domains. Finally, how the strategy suggests the implementation and how the strategy is evaluated. The paper notes that the role of National Adaptation Strategies in the wider governance of adaptation differs between countries but clearly benchmarks a new political commitment to adaptation at national policy levels. However, we also find that in most cases approaches for implementing and evaluating the strategies are yet to be defined. The paper concludes that even though the strategies show great resemblance in terms of topics, methods and approaches, there are many institutional challenges, including multi-level governance and policy integration issues, which can act as considerable barriers in future policy implementation.  相似文献