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111.
K. C. Joseph 《Journal of Earth System Science》1985,94(3):279-282
A procedure for estimating minute quantities (parts per billion) of gold is described, based on dissolution of the sample
in aqua regia, adsorption on activated charcoal, arcing of the charcoal ash, and measurement of the intensity of the emitted
spectra. 相似文献
112.
113.
L. Joseph Bachman 《Ground water》1984,22(4):460-467
Field and laboratory analyses of pH, alkalinity, and specific conductance from water samples collected from the Columbia aquifer on the Delmarva Peninsula in eastern Maryland were compared to determine if laboratory analyses could be used for making regional water-quality interpretations. On the basis of 170 field pH and specific conductance measurements, 165 laboratory pH and specific conductance measurements, and 86 field and 135 laboratory alkalinity measurements, a significant difference at the 0.1-percent level was found between laboratory and field analyses of pH and specific conductance. No significant difference was found between laboratory and field analyses of alkalinity. In most samples, laboratory pH was greater than field pH, laboratory specific conductance was less than field specific conductance, and laboratory alkalinity was equally likely to be less than, the same as, or greater than field alkalinity. Kruskal-Wallis tests of field and laboratory data grouped by north-south and east-west coordinates and by land use indicate that the difference between field and laboratory values is usually not enough to affect the outcome of the statistical tests. Thus, laboratory measurements of these constituents may be adequate for making certain regional water-quality interpretations, although they may result in errors if used for geochemical interpretations. 相似文献
114.
115.
The behavior of apatite during crustal anatexis: Equilibrium and kinetic considerations 总被引:5,自引:0,他引:5
The solubility and dissolution kinetics of apatite in felsic melts at 850°–1500°C have been examined experimentally by allowing apatite crystals to partially dissolve into apatite-undersaturated melts containing 0–10 wt% water. Analysis of P and Ca gradients in the crystal/melt interfacial region enables determination of both the diffusivities and the saturation levels of these components in the melt. Phosphorus diffusion was identified as the rate-limiting factor in apatite dissolution. Results of four experiments at 8 kbar run in the virtual absence of water yield an activation energy (E) for P diffusion of 143.6 ± 2.8 kcal-mol?1 and frequency factor (D0) of 2.23+2.88?1.26 × 109cm2-sec?1. The addition of water causes dramatic and systematic reduction of both E and D0 such that at 6 wt% H2O the values are ~25 kcal-mol?1 and 10?5 cm2-sec?1, respectively. At 1300°C, the diffusivity of P increases by a factor of 50 over the first 2% of water added to the melt, but rises by a factor of only two between 2 and 6%, perhaps reflecting the effect of a concentration-dependent mechanism of H2O solution. Calcium diffusion gradients do not conform well to simple diffusion theory because the release of calcium at the dissolving crystal surface is linked to the transport rate of phosphorus in the melt, which is typically two orders of magnitude slower than Ca. Calcium chemical diffusion rates calculated from the observed gradients are about 50 times slower than calcium tracer diffusion.Apatite solubilities obtained from these experiments, together with previous results, can be described as a function of absolute temperature (T) and melt composition by the expression: In Dapatite/meltP = [(8400 + ((SiO2 ? 0.5)2.64 × 104))/T] ? [3.1 + (12.4(SiO2 ? 0.5))] where SiO2 is the weight fraction of silica in the melt. This model appears to be valid between 45% and 75% SiO2, 0 and 10% water, and for the range of pressures expected in the crust.The diffusivity information extracted from the experiments can be directly applied to several problems of geochemical interest, including I) dissolution times for apatite during crustal anatexis, and 2) pileup of P, and consequent local saturation in apatite, at the surfaces of growing major-mineral phases. 相似文献
116.
Comparative growth of juvenile white sturgeon and striped bass: Effects of temperature and hypoxia 总被引:1,自引:0,他引:1
The influences of temperature and environmental hypoxia on the growth rates of two California anadromous fishes, white sturgeon (Acipenser transmontanus) and striped bass (Morone saxatilis) were examined. Fish (0.5–0.6 g initial weight) were fedad libitum rations ofArtemia in flow-through aquaria regulated for temperature (15, 20, and 25°C) and oxygen tension (130 and 90 torr Po 2). Growth of sturgeon was significantly greater at 20 °C compared with 15 °C, but there was no difference between 20 and 25 °C. Striped bass growth increased with each 5° increment of temeprature elevation to 3.2% body weight per d at 25 °C, the fastest growth rate measured. The temperature of maximum growth reflected the temperature of the native estuarine rearing area. Environmental hypoxia (90 torr Po 2) reduced growth of sturgeon within each temperature level, whereas striped bass growth was reduced by hypoxia only at the upper two temperatures. Sturgeon were much more active in the growth chambers than striped bass. Sturgeon activity increased with each 5 °C temperature increase under normoxia and hypoxia, except at 25 °C (hypoxia) where activity was insignificantly different from that at 20 °C (hypoxia). 相似文献
117.
Joseph P. Martino 《Climatic change》1987,11(1-2):211-235
Technological forecasting means the prediction of characteristics or use of technology. The methods used by technological forecasters are in principle no different from those used by forecasters in other application areas. However, the unique problems of the field require that the methods be adapted to those problems. This paper discusses recent developments involving refinements in the methods which have been in use for the past several decades. It also describes some important recent work on estimating upper limits to the progress of technologies, and on quantitative measures of multi-attribute technologies. Finally, it discusses several issues common to all forecasting application areas, as they are dealt with in technological forecasting. These issues include validation, disasters of forecasting, determinism in forecasting, and some examples of forecasts with practical applications. 相似文献
118.
Oysters from paired sites of high and low spatfall at three mid-Chesapeake Bay locations were analyzed for tissue copper and tissue zinc as well as copper in aufwuchs scraped from the upper (right valve) shell surface. Paired sites had no significant differences in oyster tissue copper, aufwuchs copper or oyster tissue copper-zinc ratio. In the laboratory, natural aufwuchs material on oyster shell rapidly concentrated copper up to 10× from copper-enriched estuarine water, with a partition coefficient (Ka) of 0.640 I kg?1. Aufwuchs-sorbed copper resisted depuration, suggesting a strong metal-binding substance in aufwuchs material. Eyed veliger oyster larvae (setting stage) exposed to oyster shell fragments having copper-enriched aufwuchs showed normal setting preference for bottoms and edges of shell surfaces but a slight decrease in total set with increasing aufwuchs copper concentration. Settled oyster spat died or failed metamorphosis with LD50=534 μg Cu g?1 aufwuchs. Since mid-Bay aufwuchs copper concentrations averaged 35.5 μg?1, ranging up to 103 μg g?1, oyster spatfall probably is not affected solely by present natural aufwuchs copper concentrations, but the potential for problems exists. 相似文献
119.
Potential for Solute Retardation on Monitoring Well Sand Packs and Its Effect on Purging Requirements for Ground Water Sampling 总被引:1,自引:0,他引:1
Monitoring well sand packs are theoretically capable of retarding metal ions and organic contaminants. If this retardation does indeed occur it may have a significant effect on the purging requirements of newly installed monitoring wells. Calculations based on mass balance and retardation concepts demonstrate that if common guidelines for well purging are followed, contaminants may not be detected or may be detected in lower concentrations than are actually present in the ground water. This problem is greatest in relatively shallow wells installed in low to moderate permeability materials. In most cases, the effect of solute retardation in the sand pack can be avoided simply by additional purging prior to the first sampling of the monitoring well. Common purging guidelines can then be applied to subsequent samplings. The methodology outlined in this paper can be used to calculate the purging requirements of existing monitoring wells or it may be applied to alternative monitoring well designs to test which will require the smallest volume of purged water. 相似文献
120.
Although several researchers have pointed out some advantages and disadvantages of various soil sampling designs in the presence of spatial autocorrelation, a more detailed study is presented herein which examines the geometrical relationship of three sampling designs, namely the square, the equilateral triangle, and the regular hexagon. Both advantages and disadvantages exist in the use of these designs with respect to estimation of the semivariogram and their effect on the mean square error or variance of error. This research could be used to design optimal sampling strategies; it is based on the theory of regionalized variables, in which the intrinsic hypothesis is satisfied. Among alternative designs, an equilateral triangle design gives the most reliable estimate of the semivariogram. It also gives the minimum maximum mean square error of point estimation of the concentration over the other two designs for the same number of measurements when the nugget effect is small relative to the variance. If the nugget effect is large (.90
2
or more), and the linear sampling density is >0.85r where r is the range, the hexagonal design is best. This study computes and compares the maximum mean square error for each of these designs. 相似文献