The partial molal volume of silicic acid in 0.725 M NaCl at 1°C determined by the neutralization of Na2SiO3

The partial molal volume of silicic acid ($\text{V}\text{?}\text{(Si(OH)}{}_4\text{)}$) in 0.725 M NaCl at 1°C was calculated from the measured volume change (Δ$\text{V}\text{?}{}_{\mathrm{n}}$) due to the neutralization of anhydrous sodium metasilicate with HCl and the $\text{V}\text{?}\text{(HCl)}$ and $\text{V}\text{?}\text{(NaCl)}$ obtained from the literature. $\text{V}\text{?}\text{(Si(OH)}{}_4\text{) = 59.0 cm}{}^3\text{mol}\text{? 1}$, determined under experimental conditions of pH = 2.2, compares favorably with $\text{V}\text{?}\text{(Si(OH)}{}_4\text{) = 58.9 cm}{}^3\text{mol}{}^{\mathrm{?1}}$ calculated from the measured volume change due to the hydrolysis of the meta-silicate salt at pH = 11 and from the partial molal volume due to electrostriction ($\text{V}\text{?}{}_{\mathrm{elect}}$) of water by charged Si species present in the solution at the high pH. This agreement lends support to a semiempirical model for calculating $\text{V}\text{?}{}_{\mathrm{elect}}$ in developed by Millero (1969). $\text{V}\text{?}\text{(NaOH) = ? 5.45 cm}{}^3\text{mol}{}^{\mathrm{?1}}$ in 0.725 M NaCl needed for this calculation was also determined in this work. The rate of polymerization of Si(OH)₄ at 1°C was monitored to insure that the monomer Si(OH)₄ was the main Si species present during the determination of $\text{V}\text{?}\text{(Si(OH)}{}_4\text{)}$ by neutralization of the alkali silicate. $\text{V}\text{?}\text{(Si(OH)}{}_4\text{)}$ determined in this study compares favorably with the value calculated from high pressure solubility measurements.     

A portable suction dredge for quantitative sampling in difficult substrates

A lightweight, portable suction dredge has been used for five bottom types which usually present problems to benthic investigators. Water depth ranged from 0.25 m to 5 m. By use of a 0.25 m² quadrat or using the suction end as a probe with the depth of penetration limited by a collar, quantitative samples were taken in coarse sand, fine flocculent mud, dense turtle grass (Thalassia testudinum), sparse turtle grass over coralline rubble (Porites sp.) and carbonate rock with an overlay of shell rubble. The samples consisted of the material retained by a collecting bag attached to the suction dredge. None of the commonly used benthic sampling devices could obtain samples at all stations.     

Improved mappint of the Lake Agassiz Herman strandline by integrating geological and soil maps

Several discontinuous, segmented strandlines that mark the former shores of Lake Agassiz can be found in eastern North Dakota. These strandlines are difficult to map and correlate because of their segmented nature. Better mapping would benefit researchers working on a number of problems involving Lake Agassiz including dating the strandlines, reconstructing the lake's history, and calculation of asthenosphere viscosity beneath the Lake Agassiz basin. Elongated soil delineations representing beach-indicative soils with a north-northwest trend and extending from currently mapped areas of the Herman strandline were identified on Grand Forks County soil maps. This information was combined with the geologic map of Grand Forks County in an attempt to better define the location of the Herman strandline in the southern part of the county. This approach worked well, and it is recommended that similar studies be attempted on other Lake Agassiz strandlines in North Dakota and the surrounding area.     

Remarks on the viscosity concept in the early universe

Some aspects of viscous cosmological models, mainly of Bianchi type-I, are studied, in particular with the purpose of trying to obtain a natural explanation of why the entropy per baryon in the universe, ~ 10⁹, is so large. Using the FRW metric it is first shown, in agreement with previous workers, that the expressions for the bulk viscosity as derived from kinetic theory in the plasma era is incapable of explaining the large value of. However it is possible to imagine the viscosity to be an impulse viscosity operative in one or several phase transitions in the early universe. This is the main idea elaborated on in the present paper. It is shown that in thek = 0 FRW space, an impulse bulk viscosity _infl ~ 10⁶⁰ g cm^–1 s^–1) acting at the phase transition at the end of the inflationary epoch corresponds to the correct entropy. If the space is anisotropic, it is natural to exploit the analogy with classical fluid dynamics to introduce the turbulent viscosity concept. This is finally discussed, in relation to an anisotropy introduced in the universe via the Kasner metric.     

The behavior of fly-ash derived arsenic in seawater

With the rising cost of oil the electric power generating companies are turning to coal as a fuel source. Large amounts of fly ash are produced as a by product of coal combustion. This fly ash must then be disposed of, with the oceans being considered an alternative to land fill disposal. This research investigated the sorptive behavior of the surface-associated arsenic and utilized the results to project arsenic's impact on the water column during the ocean disposal of fly ash.Several acid digests were investigated to determine an effective method of arsenic recovery from fly ash. Of these, the HCl digest was the most effective technique, yielding 100% arsenic recoveries from fly-ash particles. The arsenic content of the fly ashes studied varied from 69 ± 11 μg g⁻¹ to 323 ± 24 μg g⁻¹, reflecting differences in the arsenic content of the source coal. In both seawater and freshwater there is an increase in arsenic desorption with increasing pH. The greatest release of arsenic occurred at pH 12 with generally over 80% of the surface arsenic released.Fly ash in contact with seawater and freshwater can exhibit either acidic or alkaline tendencies depending upon the soluble elemental composition on the surface of the flyash particle. The acidic ashes were shown to leach a greater percentage of arsenic (16.9%) than the more alkaline ashes (8.2%). During these leaching studies in seawater, arsenic was found to leach in both the pentavalent and trivalent oxidation state. The pentavalent state was predominant, comprising 77% of the arsenic initially desorbed.The dissolution in seawater of arsenic was utilized to assess the possible impact of the ocean disposal of fly ash. Based upon these data it appears that the natural levels of arsenic in the water column would not be significantly increased. Further research is needed on the fate of fly-ash particles in marine sediments.     

Rainfall and land management effects on erosion and soil properties in traditional Brazilian tobacco plantations

No-tillage and inter-crops have been progressively introduced into traditional Brazilian tobacco plantations. However, there is a lack of information about their impact on soil erosion rates and soil properties. We studied 10 experimental plots in Paraná (Brazil) that rotated from no-tillage tobacco to two different inter-crop types (black beans and oats) and conventionally tilled tobacco to quantify erosion rates from September 2014 to February 2016. The results show that soil loss (18 Mg ha^?1) and runoff coefficient (8.3%) were higher under conventional tillage tobacco than under no-tillage tobacco (3.4 Mg ha^?1 and 0.6%). Bulk density was higher at the end of the cropping cycle than at the beginning. We concluded that conventional crops increased soil erosion, and the use of inter-crops and no-tillage is highly recommended for soil and water conservation. The findings should be valid for other regions that have similar cropping systems and environmental conditions.