Emission spectrographic estimation of gold

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.     

Field and Laboratory Analyses of Water from the Columbia Aquifer in Eastern Maryland

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.     

Comparative growth of juvenile white sturgeon and striped bass: Effects of temperature and hypoxia

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 P_{o 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 P_{o 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).     

Recent developments in technological forecasting

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.     

Oxygen isotopic composition of Central Sierra Nevada precipitation, I. Identification of ice-phase water capture regions in winter storms

Measurements of the stable isotopic ratios of oxygen and simultaneously observed ice crystal structure in freshly fallen snow, have been used to estimate the weighted mean altitudes of ice-phase precipitation formation in winter clouds over the Central Sierra Nevada.Observations of dominant, diffusionally grown ice-crystal habits were used to estimate relatively narrow ranges of temperatures of initial formation of the precipitation particles using the Nakaya (1954) ice-crystal classification techniques. The mean oxygen isotope ratio ¹⁸O/¹⁶O for each snow sample, together with local upper air soundings, were used to estimate ranges of temperature-altitude within the clouds where the precipitating particles had captured their ice-phase water. For this initial study, snow samples were collected each five (5) to ten (10) minutes during three snowfall periods on 27 January, 26 February and 28 February, 1983.For the 27 January case, the ice formation mechanism was predominantly vapor deposition and hence the narrow range of temperatures determined by the ice-crystal habits was directly relatable to the mean δ¹⁸O value.The 26 and 28 February cases were more complicated because the solid-phase precipitation was formed by vapor deposition and by freezing of drops and droplets (which occurs without isotopic fractionation). In these cases, the oxygen isotopic composition of the snow reaching the ground was representative of solid phase precipitation which had formed at warmer temperatures than those corresponding to the primary ice-crystal habits alone. There was no apparent relationship between δ¹⁸O values and surface temperature at the sampling site.If relationships between ¹⁸O/¹⁶O and temperature-altitude are established for this geograpic region for winter snowfall conditions, this crystal habit—isotopic composition technique can provide knowledge about the regions of the clouds in which the ice-phase precipitation is forming over the Central Sierra Nevada.     

Penetration of sunlight into a canopy: Explicit models based on vertical and horizontal leaf projections

The projections of leaf areas onto a horizontal plane and onto a vertical plane are examined for their utility in characterizing canopies for sunlight penetration (direct beam only) models. These projections exactly specify the penetration if the projections on the principal plane of the normals to the top surfaces of the leaves are in the same quadrant as the Sun. Inferring the total leaf area from these projections (and therefore the penetration as a function of the total leaf area) is possible only with a large uncertainty (up to ±32%) because the projections are a specific measure of the total leaf area only if the leaf angle distribution is known. It is expected that this uncertainty could be reduced to more acceptable levels by making an approximate assessment of whether the zenith angle distribution is that of an extremophile canopy. An extremophile canopy would have the maximum leaf area possible for given set of projections. Simple leaf projection measurements would then become a practical substitute for detailed measurements of the leaf angle distribution. This is not true if for a fraction of the canopy, the leaf normal projections fall in the non-solar quadrant. In this case, accurate and detailed information about the leaf orientation is required for assessing the penetration; the horizontal and vertical projections are inadequate for this purpose.     

Oyster (Crassostrea virginica,Gmelin) spat settlement and copper in aufwuchs

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.     

Potential for Solute Retardation on Monitoring Well Sand Packs and Its Effect on Purging Requirements for Ground Water Sampling

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.