The dispersion of 222Rn from emitted waste gases at Wairakei geothermal power station, New Zealand, is modelled. It is concluded that resulting concentrations in the nearby township of Taupo will never exceed the maximum permissible in any meteorological situation. The greatest possible accumulation is calculated to be less than one eighth of the normal background radon concentration. A more realistic set of assumptions predicts long-term mean concentrations about 4% of background levels. A new geothermal power station, Ohaaki, a factor of three times more distant, is calculated to produce ten times lower concentrations than Wairakei. Measurements using a few passive solid-state radon detectors show that the natural variation of radon concentrations greatly exceeds any calculated contribution from either geothermal station; hence, much of the radon is probably due to more local minor sources. Local sources have increased due to draw-off of ground water by the Wairakei station. Thus, there could be some indirect contribution to radon concentrations by its operation. The measured six-month integrated mean radon concentration at Taupo is a significant fraction of the maximum permissible concentration. It seems likely that natural sources alone may lead to levels in air which are above the maximum when temperature inversion exists. It is concluded that these two geothermal power plants are unlikely to produce concentrations of radon hazardous to the population or to plant workers. 相似文献
DESIGN ON THE LAND: the development of Landscape Architecture Norman T. Newton Belknap Harvard
COMMUNITY CENTERS AND STUDENT UNIONS Eugene D. Sternberg and Barbara E. Sternberg Van Hostrand Reinhold Company, New York.
DECISION AND CONTROL by Stafford Beer, John Wiley and Sons, Inc., New York, 1966 (3rd printing, 1970)
INDUSTRIAL DYNAMICS by Jay W. Forrester, M.I.T. Press, Cambridge, Mass., 1961. S.1O.5O.
PRINCIPLES OF SYSTEMS by Jay W. Forrester. Wright‐Allen Press, Inc., Cambridge, Mass., 1968.
PUBLIC INQUIRIES AS AN INSTRUMENT OF GOVERNMENT R.E. Wraith and G.B. Lamb George Allen & Unwin Ltd. for the Royal Institute of Public Administration, London 1971, £4.50.
SYSTEMS APPROACH AND THE CITY M.D. Mesarovic and A. Reisman (eds.) North‐Holland Publishing Co., Amsterdam and London, 1972.
SIMULATION IN THE CLASSROOM John L. Taylor and Rex Walford Penguin Books, London, 1972. 45p.
DEVELOPMENT BUILDING: THE TEAM APPROACH C.W. Griffin John Wiley & Sons, Inc. for the American Institute of Architects, New York, 1972.相似文献
Emissions of ammonia were measured from livestock excreta and fertilisers applied to grass swards, from grazed paddocks, from decomposing grass herbage and from an animal house containing dairy cows. Emissions from urine, dung, slurry and fertilisers were determined using a system of wind tunnels with each tunnel covering an area of 1 m(2). Emissions from grazed swards were determined using a micrometeorological mass balance method. From the results of these measurements, together with other published information, an inventory for ammonia emissions has been calculated for grassland and livestock production systems over the UK as a whole. It is estimated that emissions from grassland and cattle and sheep production amount to about 230 kt NH(3)-N annually, while emissions from pig and poultry production amount to about 40 kt and 80 kt NH(3)-N, respectively. 相似文献
In 1986, eggs were collected and productivity estimated at four great blue heron (Ardea herodias) colonies on the coast of British Columbia. Polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were present in all eggs in a qualitatively similar pattern among colonies. PCDD levels were significantly elevated at a colony near a kraft pulp mill at Crofton on Vancouver Island, although there was no correlation between the number of young raised in a nest and levels of either PCDDs, PCDFs, PCBs, organochlorine pesticides or mercury. In 1987, heron productivity was normal at three colonies, while the colony at Crofton failed to raise any young. A normal complement of eggs were apparently laid in about 57 nests, but during incubation they were destroyed and the broken eggshells were found in and beneath the nests. Analysis of eggs salvaged from nests showed that 2378-TCDD levels were about three times higher in 1987 than in 1986. At a colony in Vancouver, 2378-TCDF levels were significantly higher in 1987 than 1986 eggs. Levels of organochlorine pesticides and total mercury in eggs were generally low; highest residue levels were found in two mainland colonies, particularly at one adjacent to an agricultural area. Total PCB levels were low and did not differ significantly among locations. Analysis of PCB congener ratios indicated different sources of PCBs. Regurgitated prey samples collected in 1986 from four locations had generally low levels of PCDD, PCDF, mercury, lead and cadmium contamination. 相似文献
