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101.
With the ending of the Cold War, the US Department of Energy is responsible for the remediation of radioactive waste and disposal of land no longer needed for nuclear material production or related national security missions. The task of characterizing the hazards and risks from radionuclides is necessary for assuring the protection of health of humans and the environment. This is a particularly daunting task for those sites that had underground testing of nuclear weapons, where the radioactive contamination is currently inaccessible. Herein we report on the development of a Science Plan to characterize the physical and biological marine environment around Amchitka Island in the Aleutian chain of Alaska, where three underground nuclear tests were conducted (1965–1971). Information on the ecology, geology, and current radionuclide levels in biota, water, and sediment is necessary for evaluating possible current contamination and to serve as a baseline for developing a plan to ensure human and ecosystem health in perpetuity. Other information required includes identifying the location of the salt water/fresh water interface where migration to the ocean might occur in the future and determining groundwater recharge balances, as well as assessing other physical/geological features of Amchitka near the test sites. The Science Plan is needed to address the confusing and conflicting information available to the public about radionuclide risks from underground nuclear blasts in the late 1960s and early 1970s, as well as the potential for volcanic or seismic activity to disrupt shot cavities or accelerate migration of radionuclides into the sea. Developing a Science Plan involved agreement among regulators and other stakeholders, assignment of the task to the Consortium for Risk Evaluation with Stakeholder Participation, and development of a consensus Science Plan that dealt with contentious scientific issues. Involvement of the regulators (State of Alaska), resource trustees (U S Fish and Wildlife Service), representatives of the Aleut and Pribilof Island communities, and other stakeholders was essential for plan development and approval, although this created tensions because of the different objectives of each group. The complicated process of developing a Science Plan involved iterations and interactions with multiple agencies and organizations, scientists in several disciplines, regulators, and the participation of Aleut people in their home communities, as well as the general public. The importance of including all parties in all phases of the development of the Science Plan was critical to its acceptance by a broad range of regulators, agencies, resource trustees, Aleutian/Pribilof communities, and other stakeholders.  相似文献   
102.
103.
Isotopic exchange occurs between coral skeleton and 45Ca++ and H14CO 3 - in seawater. Exchange of 14C onto skeletons is more rapid than exchange of 45Ca++. Exchange of 14C from skeletons to seawater takes place more slowly than exchange of 45Ca++ to seawater. When living coral is incubated in the dark with radioisotopes for 1 h, the tissues contain considerably more radioactivity than is associated with the skeleton. The tissue radioactivity reflects permeation of tissues and coelenteron by radioactive compounds from the incubation seawater. Addition of alkalis to cardioactive seawater results in a radioactive precipitate, part of which becomes associated with any coral skeleton present, and part of which forms on the wall of the containing vessel. Strong alkali removes biologically-deposited radioisotope from coral skeletons. Deposition, of 14C from H14CO 3 - in skeletons of living coral incubated in the dark is greater than in dead coral. The reverse situation occurs with 45Ca++.  相似文献   
104.
Seasonal changes of respiratory metabolism and biochemical composition were studied in Actinia equina L. (Cnidaria: Anthozoa) collected in 1982 and 1983 from two shore locations in Spain. Changes of metabolic activity follow closely those of biochemical constituents, particularly carbohydrates and lipids, showing maxima in late fall and spring. Weight dependence, established according to the exponential equation y=a xb (x=weight), results in virtually isometric relationships for proteins, total lipids and sugars but not glycogen. Allometry for this last compound represents a reduction in glycogen level in connection with size decrease; this weight effect declines when glycogen levels rise, both in field and laboratory fed anemones, thus suggesting a stronger influence of food availability on storage in small anemones.  相似文献   
105.
ABSTRACT: A method is presented for predicting base flow using easily measured, or estimated, hydrogeologic parameters. A mathematical model based upon the theory of subsurface flow to parallel drains is applied to a small watershed in Oklahoma. An example of model application is presented for a five-year period of record from this small watershed. Three years of data are used to calibrate the model, and two years of data are used for model validation. Hydrographs of observed and predicted base flow are presented for the five-year period of record. We concluded from this limited application of the model, on a small watershed, that the modeling techniques discussed herein were valid and should be tested for longer time periods on a larger watershed to determine their general applicability.  相似文献   
106.
In order to study taxon richness, biodiversity and abundance patterns in the North Atlantic from temperate latitudes through Arctic to high Arctic latitudes, we recorded the faunas (at ELWS level) colonizing 20 cobbles from three sites at each of seven boulder-field localities (south-west England, 50°N; Wales, 51°N; west Scotland, 56°N; Iceland, 64°N; Tromsø, 70°N; Svalbard, 77°N, 79°N). Inverse correlations were found between latitude and all measures of richness (species, orders, and phyla numbers) and biodiversity (S–W, P). However, these correlations were driven mostly by the consistently impoverished Arctic sites; an even cline of decreasing diversity from south to north did not exist. Multidimensional scaling revealed two communities, temperate–subarctic species-rich and high arctic species-poor. Evenness as measured by Pielou’s index was similar across all latitudes. Abundance data exhibited a similar trend to the species richness and diversity data with a significant negative correlation with latitude, but when Arctic data were excluded the correlation vanished.  相似文献   
107.
Compensation point and light-saturation values were determined from oxygen-exchange experiments with branches and isolated zooxanthellae from the staghorn coral Acropora acuminata. Branches and dense suspensions of zooxanthellae showed similar lightresponse curves for oxygen exchange, with light saturation at about 23 Klux (300 W. m-2) and compensation point occurring between 4 and 6 Klux (60–80 W. m-2). Zooxanthellae appear to be mutually shaded in dense suspensions and coral tissues. The effects of metabolic inhibitors, including photosynthetic and respiratory inhibitiors, on oxygen exchange in coral branches and isolated zooxanthellae are presented. Bubbles formed on coral tissues and on several macroalgae under conditions of high illumination contained large amounts of oxygen, suggesting that a high oxygen tension may occur in coral tissues during the day. Photorespiration and dissolved organic carbon production by suspensions of zooxanthellae are discussed in relation to a high oxygen tension which probably occurs in coral tissues during daylight.  相似文献   
108.
This paper presents phenological weighting factors to be applied to AOT40 (accumulated ozone exposure above a threshold of 40 nl l(-1)) ozone exposure-response relationships for crops at different growth stages. The quantification of such factors represents a step-forward in the derivation of Level II critical levels for ozone. The weighting factors presented are derived from published literature on the sensitivity of wheat (Triticum aestivum), bean (Phaseolus vulgaris) and plantain (Plantago major) to ozone at different growth stages. Weighting functions were calculated using either multiple linear regression or the reciprocal residual mean square (RMS(-1)). The resulting weights were transformed into multiplication factors to be applied to the monthly AOT40 during the 3-month assessment period of critical level exceedance. Interspecific differences were too large to allow for the development of a unified weighting function for the three species considered. For wheat grain yield, the derived multiplication factors varied by almost four-fold (0.40, 1.06, 1.54), while those for bean pod yield varied by only about 25% (0.85, 1.01, 1.14). The available data for plantain were restricted to short-term studies conducted under controlled conditions. These data were not suitable for the derivation of weighting factors comparable to those derived for bean and wheat. Based on known differences in wheat development and phenology across Europe, the need for a geographic differentiation of the time period for the calculation of the critical level exceedances is also discussed and examples provided of the adoption of the derived weightings in the mapping of critical level exceedances. Differences between critical level exceedance maps using weighted and unweighted AOT40 calculations are discussed.  相似文献   
109.
CO(2) assimilation rate, stomatal conductance and chlorophyll content of current and previous years' needles of Norway spruce were measured in May 1988, 205 days after the cessation of ozone fumigation during the summer of 1987. Rates of assimilation were consistently higher for both needle year age classes for ozone fumigated trees in comparison to control trees, although only statistically significant for part of the day for current year's needles. A 26% and 48% stimulation, overall, in mean daily rates of assimilation for current and previous years' needles of ozone fumigated trees was observed. This was due to an enhanced apparent quantum yield and light saturated rate of assimilation of ozone fumigated trees. The temperature response regression of assimilation versus temperature was also greater, such that at any given temperature, assimilation was higher for ozone treated trees than control trees. Stomatal conductance was greater for ozone fumigated trees than the controls, but this was only marginally statistically significant. Moreover, there was a consistent increase in chlorophyll content in both year classes in ozone-treated trees. These results are discussed in relation to a possible long term effect of ozone fumigation upon the processes of conifer winter hardening and spring de-hardening.  相似文献   
110.
We report a case in which mosaicism of trisomy 13 was detected in 4/10 cells (40 per cent) in amniotic fluid cell cultures, followed by a low rate of mosaicism (1/160 cells) detected in a fetal blood sample. This finding presents a dilemma both for the genetic counsellor and for the parents in determining whether or not to terminate the pregnancy.  相似文献   
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