921 resultados para Radiochemical laboratories
Resumo:
Uranium series nuclide concentrations have been measured on sediments from five box cores from an equatorial Pacific transect. 230Thexcess activities show discontinuities at the Holocene-glacial boundary as dated by 14C. The glacial sedimentation rates determined by 230Th and 14C are 2.5-3.0 cm/kyr. The Holocene rates from 230Th are much lower than those dated by 14C (1.9-2.3 cm/kyr) because of carbonate dissolution. 230Th sedimentation fluxes exceed water column supply by factors of 1.2-1.8 in the Holocene and 1.8-3.0 in the glacial sections. A number of models have been applied to calculate carbonate dissolution rates. The results show that carbonate dissolution rates in the Holocene (in g/cm**2 kyr) equal 1.5 * 10**-3 exp (1.4D) where D is water depth in kilometers. A point-by- point estimation of sediment fluxes through time show that clay accumulation rates in the area have been near constant at 0.1-0.2 g/cm**2 kyr over the past 20 kyr whereas carbonate accumulation rates have decreased dramatically from 0.6-1.0 g/cm**2 kyr in the glacial sections of the cores to 0.2-0.6 g/cm**2 kyr in the Holocene. The errors caused by the uncertainties in the age of the termination of the last glacial period have been investigated and results show that a range of 11-14 kyr leads to an error upper limit of about 30% in the estimation of CaCO3 dissolution rates. The response time of CaCO3 and 230Thex concentrations in the mixed layer of sediments due to an impulse of change in CaCO3 dissolution rate has also been discussed, showing that the observed changes in carbonate dissolution may be explained in terms of a single or a continuous change, depending upon the thickness of the mixed layer.
(Table 4 bis, page 194), Radiochemical data on four successive Mn-rich layers of a West Timor nodule
Resumo:
This paper examines how a country which has been successful in creating agglomeration of a manufacturing industry has faced various types of product-related environmental regulations. Then the paper shows how the government and testing laboratory have taken measures to adapt to PRERs overseas in response to the needs by firms affected by regulations. In reaction to the introductions of PRERs overseas, Malaysia also has introduced equivalent policies domestically, proving that PRERs have spread to Malaysia.
Resumo:
This paper examines how a country which has been successful in creating agglomeration of a manufacturing industry has faced various types of product-related environmental regulations. Then the paper shows how the government and testing laboratory have taken measures to adapt to PRERs overseas in response to the needs by firms affected by regulations. In reaction to the introductions of PRERs overseas, Malaysia also has introduced equivalent policies domestically, proving that PRERs have spread to Malaysia.
Resumo:
This paper examines how a country which has been successful in creating agglomeration of a manufacturing industry has faced various types of product-related environmental regulations. Then the paper shows how the government and testing laboratory have taken measures to adapt to PRERs overseas in response to the needs by firms affected by regulations. In reaction to the introductions of PRERs overseas, Malaysia also has introduced equivalent policies domestically, proving that PRERs have spread to Malaysia.