Proton flux and radiation dose from galactic cosmic rays in the lunar regolith and implications for organic synthesis at the poles of the Moon and Mercury

Galactic cosmic rays are a potential energy source to stimulate organic synthesis from simple ices. The recent detection of organic molecules at the polar regions of the Moon by LCROSS (Colaprete, A. et al. [2010]. Science 330, 463–468, http://dx.doi.org/10.1126/science.1186986), and possibly at the poles of Mercury (Paige, D.A. et al. [2013]. Science 339, 300–303, http://dx.doi.org/10.1126/science.1231106), introduces the question of whether the organics were delivered by impact or formed in situ. Laboratory experiments show that high energy particles can cause organic production from simple ices. We use a Monte Carlo particle scattering code (MCNPX) to model and report the flux of GCR protons at the surface of the Moon and report radiation dose rates and absorbed doses at the Moon’s surface and with depth as a result of GCR protons and secondary particles, and apply scaling factors to account for contributions to dose from heavier ions. We compare our results with dose rate measurements by the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) experiment on Lunar Reconnaissance Orbiter (Schwadron, N.A. et al. [2012]. J. Geophys. Res. 117, E00H13, http://dx.doi.org/10.1029/2011JE003978) and find them in good agreement, indicating that MCNPX can be confidently applied to studies of radiation dose at and within the surface of the Moon. We use our dose rate calculations to conclude that organic synthesis is plausible well within the age of the lunar polar cold traps, and that organics detected at the poles of the Moon may have been produced in situ. Our dose rate calculations also indicate that galactic cosmic rays can induce organic synthesis within the estimated age of the dark deposits at the pole of Mercury that may contain organics.     

Groundwater Resources and Their Role in Water Supply to Crimea

The processes of formation and distribution of the resources of fresh groundwater and surface water in the territory of Crimea Peninsula are considered. Water availability in the natural–historic and administrative regions of the republic is characterized. The proportions between different categories of groundwater resources are shown with their role in water supply to Crimea taken into account. The presentday development of groundwater resources is analyzed and the possible increase in water consumption meeting geoecological requirements is substantiated.     

Point-block covariance: A general solution for the two-dimensional stationary random functions

The application of the theory of random functions to problems of ore evaluation may involve computations of the covariance between the mean value of a given block and the functional value at a given point. However, an analytical solution for such a covariance does not exist for nonspherical blocks and for commonly applied models of covariance functions. Further, because this covariance is a function of the spatial arrangements of the block and the point, it has to be evaluated numerically each time for given point—block arrangements. This paper presents a readily available general solution to this problem in the form of a series of graduated curves which, together with some geometric manipulations, may be used to compute the covariance between a pointand a two-dimensional block for all possible point—block arrangements. The availability of the graph thus eliminates the necessity of using the time-absorbing programs on computers for such computations. Finally, many of the approximations that are made in order to avoid cumbersome covariance evaluations are no longer necessary due to the ease of such computations with the help of the graph provided.     

N and O isotope effects during nitrate assimilation by unicellular prokaryotic and eukaryotic plankton cultures

In order to provide biological systematics from which to interpret nitrogen (N) and oxygen (O) isotope ratios of nitrate (¹⁵N/¹⁴N, ¹⁸O/¹⁶O, respectively) in the environment, we previously investigated the isotopic fractionation of nitrate during its assimilation by mono-cultures of eukaryotic algae (Granger et al., 2004). In this study, we extended our analysis to investigate nitrate assimilation by strains of prokaryotic plankton. We measured the N and O isotope effects, ¹⁵ε and ¹⁸ε, during nitrate consumption by cultures of prokaryotic strains and by additional eukaryotic phytoplankton strains (where ε is the ratio of reaction rate constants of the light vs. heavy isotopologues, ^lightk and ^heavyk; ε = ^lightk/^heavyk − 1 × 1000, expressed in per mil). The observed ¹⁵ε ranged from 5‰ to 8‰ among eukaryotes, whereas it did not exceed 5‰ for three cyanobacterial strains, and was as low as 0.4‰ for a heterotrophic α-protoeobacterium. Eukaryotic phytoplankton fractionated the N and O isotopes of nitrate to the same extent (i.e., ¹⁸ε ∼ ¹⁵ε). The ¹⁸ε:¹⁵ε among the cyanobacteria was also ∼1, whereas the heterotrophic α-proteobacterial strain, which showed the lowest ¹⁵ε, between 0.4‰ and 1‰, had a distinct ¹⁸ε:¹⁵ε of ∼2, unlike any plankton strain observed previously. Equivalent N vs. O isotope discrimination is thought to occur during internal nitrate reduction by nitrate reductase, such that the cellular efflux of the fractionated nitrate into the medium drives the typically observed ¹⁸ε:¹⁵ε of ∼1. We hypothesize that the higher in the ¹⁸ε:¹⁵ε of the α-proteobacterium may result from isotope discrimination by nitrate transport, which is evident only at low amplitude of ε. These observations warrant investigating whether heterotrophic bacterial assimilation of nitrate decreases the community isotope effects at the surface ocean.     

Facies Structure and Quantitative Parameters of Pleistocene Sediments of the Bering Sea

Lithofacies zoning is described for the first time for the Neo- and Eopleistocene of the Bering Sea. Four lithofacies sedimentation zones are distinguished: (I) terrigenous; (II) siliceous–terrigenous; (III) siliceous, and (IV) volcanoterrigenous ones. Corresponding maps were treated using Ronov volumetric method to quantify sedimentation parameters for distinguished lithofacies zones (subzones) and types of Pleistocene sediments. It was revealed that terrigenous sediments predominate over other sediments. Accumulation of the terrigenous sediments was more intense (by 1.4 times) in the Neopleistocene than in the Eopleistocene. The sedimentation rate of siliceous sediments of the Bowers Ridge in the Eopleistocene was two times higher than in the Neopleistocene.     

A possible dependence of tectonic strength on the age of the crust in Asia

In Asia, the intensity and style of active tectonics appears to depend on the age of the last orogenic activity. The shields have remained essentially undeformed during the India-Eurasian collision, but Paleozoic and Mesozoic orogenic belts apparently have been reactivated by this collision, with a suggestion of greater reactivation and more diffuse deformation of the younger belts. If the greater observed heat flow in regions of more recent orogenic activity reflects, at least in part, a greater heat flow from the mantle beneath the younger belts, then the temperatures in the mantle beneath the younger belts should be higher than beneath older belts and shields. Because of the strong dependence on temperature of the creep strength of minerals, particularly of olivine, the crust and mantle beneath the hotter, younger belts should be much weaker than those beneath older belts. This difference in temperature, and consequent difference in strength, may be the cause of the greater reactivation of younger belts.     

Influence of wind upon water quality in Liverpool Bay

Comprehensive distribution patterns of physical and chemical characteristics have been obtained from a series of cruises in Liverpool Bay. The marked feature of these distributions was their temporal variability, suggesting that the surface residual circulation is also temporally variable. The influence of wind stress upon the circulation pattern and hence water quality of this sea area is illustrated.