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91.
92.
This paper describes a linear program-based computer model which has been developed to identify the most effective spending patterns for environmental cleanup based on public preferences and spending limitations. The inputs to the model include the costs of removing each residual studied from its various sources. The objective function is the total “value of removal”. The factor added for each residual consists of a value for the residual multiplied by the quantity or fraction removed.Results of the analysis relate to and support current and projected policy decisions by the U.S. Environmental Protection Agency (EPA) for air and water programs. In addition, the results of the analysis suggest that EPA undertake a redirection of the Nation's resources among residual control programs.  相似文献   
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It is doubtful that large-scale industrial utilization of the fast breeding reactor will ever be possible. It is, however, probable that the thorium reactor, for which three plans already exist, will be realized. There is enough thorium to supply thorium reactors up to the next glacial period.  相似文献   
95.
Color variation is used in taxonomic classification of reef fishes, but it may not reliably indicate evolutionary divergence. In the central Pacific, there are three color morphs of the flame angelfish, Centropyge loriculus: a red morph that occurs primarily in the Hawaiian archipelago, the endemic Marquesan color morph with reduced black markings, and an orange morph that occurs throughout the rest of Oceania. The red and orange morphs co-occur at Johnston Atoll (1,300 km south of Hawai’i), but intermediate forms have not been reported. To determine whether the three color morphs represent distinct evolutionary lineages, we compared 641 base pairs of mitochondrial cytochrome b. Forty-one closely related haplotypes were observed in 116 individuals. Analysis of molecular variance (AMOVA) indicated no significant genetic structure among color morphs (ΦST = 0.011, P = 0.147). Likewise, there was no significant pairwise structure between sampling locations, separated by up to 5,700 km, after a Bonferroni correction (ΦST = 0.000–0.080, P = 0.0130–0.999). Genetic studies in conjunction with larval distribution data indicate that Centropyge species are highly dispersive. While there is a strong geographic component to the distribution of color morphs in C. loriculus, we find no evidence for corresponding genetic partitioning. We do not rule out an adaptive role for color differentiation, but our data do not support emerging species.  相似文献   
96.
Radon mass exhalation rate of soil samples was measured using an exhalation chamber of 10 dm(3) volume and a Lucas cell. The results show that mass of sample, grain size and water content influence the radon mass exhalation rate. For soil of (226)Ra activity concentration about 2500 Bq kg(-1) and samples within the range from 0.20 kg to 0.50 kg, the radon mass exhalation rate values are higher than those for samples of other masses. The observed radon exhalation rate is an inverse function of the average grain size. At the water content about 6% by weight, the radon mass exhalation rate reaches maximum, then it decreases with both increasing and decreasing of the water content in the sample.  相似文献   
97.
The geochemical partitioning of copper (Cu), lead (Pb), and zinc (Zn) was examined in benthic sediment profiles (0- to 20-cm depth interval) composed of relatively coarse (65-90% sand-sized particles), noncohesive, suboxic material (Eh +120 to +260 mV). Total Cu, Pb, and Zn concentrations ranged from 8.3 to 194, 16.3 to 74.8, and 30.1 to 220 mg/kg, respectively, and were related to vertical trends in sediment texture. The observed distribution coefficients describing solid-solution partitioning were in the range of 100 to 1000 L/kg. The geochemical partitioning of solid-phase Cu, Pb, and Zn between six operationally defined fractions was examined with a sequential extraction scheme. The association of Cu, Pb, and Zn with amorphous oxides, crystalline oxides, and organic matter was linearly dependent on the abundance of each respective phase. For retention by amorphous oxide minerals, the observed stoichiometry ranged from 5.2 to 23.7 mg/g for Cu, 12.8 to 21.5 mg/g for Pb, and 23.1 to 85.7 mg/g for Zn. Corresponding values for association with crystalline oxides were an order of magnitude less than those for amorphous oxides, indicating a lesser affinity of trace metals for crystalline oxides. The stoichiometric relationships describing association with organic matter ranged from 17.6 to 54.0 mg/g for Cu, 6.1 to 9.6 mg/g for Pb, and 6.4 to 16.4 mg/g for Zn. The results from this study provide an insight into processes controlling trace metal partitioning in coarse-textured, suboxic, estuarine sediments.  相似文献   
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Summary Philanthropy has been vital to the environmental movement in the United States. Individual gifts and foundation grants have sustained the organizations, people, and programs of the independent sector which, although small in comparison to either government or industry, has contributed much through shaping environmental issues and setting directions for public policy. The importance of these efforts belies their size and the small amount of money which has supported them. Recent trends, however, indicate that the amount of support received by environmental groups may have peaked, a development which could have disturbing consequences for the field.Prior to this, E. Ames was Programme Officer for the Ford Foundations's Office of Resources and Environment. Former Director of the Wilderness Society and the Open Space Institute. Associated with Harvard University and the Carnegie Institution, Washington.  相似文献   
100.
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