Importance of orographic precipitation to the water resources of Monteverde,Costa Rica

Monteverde, Costa Rica harbors montane forests that exemplify the delicate balances among climate, hydrology, habitat, and development. Most of the annual precipitation to this region arrives during the wet season, but the importance of orographic precipitation during the dry and transitional seasons should not be underestimated. Development associated with ecotourism has put significant stress on water resources, and recent work has shown evidence that changes in regional land-cover and global climate may lead to reduced precipitation and cloud cover and a subsequent decline in endemic species.     

The Application of a Statistical Trend Analysis Model to Ground Water Monitoring Data from Solid Waste Landfills

A statistical trend methodology is used to compare ground water quality between eight landfill sites in western Michigan as a case study. Monitoring data were collected over a 15-year period on 36 parameters at an upgradient and downgradient well selected at each of the eight sites. This yielded a total of 576 monitoring data sets available for analysis. New trend and contamination indices are introduced that are used to compare ground water contamination between these eight sites. These indices are used to assess each landfill's relative potential for environmental harm.
Many questions remain unanswered, but what is demonstrated here is that this type of methodology has the potential to be used to assess trends of ground water chemistry concentrations at landfill sues in a region. A specific purpose of such an assessment could be to provide a quantified basis for the prioritization of funds allocated for cleanup of contaminated landfill sites. Having a technical capability to reduce large amounts of ground water monitoring data to appropriate summaries, which then can be used to assess environmental contamination between several sites, could also have important economic and health implications in other settings. Hopefully this paper will encourage further development of such technologies for these purposes.     

Activation of Persulfate by Surfactants under Acidic and Basic Conditions

Activated persulfate is a commonly used oxidant source used for in situ chemical oxidation (ISCO) for remediation of subsurface contamination. Surfactants are sometimes used in ISCO to desorb contaminants and dissolve nonaqueous phase liquids (NAPLs). The potential activation of persulfate by such surfactants was investigated, and the reactive oxygen species generated by persulfate in the presence of anionic, nonionic, and cationic surfactants were determined. Twenty surfactants were screened; most activated persulfate to generate reductants + nucleophiles at acidic and basic pH. The most reactive anionic, nonionic, and cationic surfactants (Lankropol 4500, polyethylene glycol 400, and Ethoduomeen T/25) were investigated in more detail. All three surfactants activated persulfate; however, the cationic surfactant showed the most potential for persulfate activation with high fluxes of hydroxyl radical and reductants + nucleophiles. The results of this research demonstrate that surfactants added to ISCO systems often activate persulfate to generate reductants at both acidic and basic pH, and hydroxyl radical at basic pH. These findings provide a new paradigm for persulfate activation in surfactant in situ chemical oxidation (SISCO) systems; pH regimes >11 may not be necessary for persulfate activation resulting in cost savings and potentially more effective activation of persulfate.     

Systematic Errors Induced by the Elliptical Power-law model in Galaxy-Galaxy Strong Lens Modeling

The elliptical power-law model of the mass in a galaxy is widely used in strong gravitational lensing analyses.However,the distribution of mass in real galaxies...     

Disturbance of isotope systematics during experimental shock and thermal metamorphism of a lunar basalt with implications for Martian meteorite chronology

Abstract– To better determine the effects of impact‐related processes on radiometric chronometers in meteorites, we undertook an isotopic study of experimentally shocked and heated samples of lunar basalt 10017. Shock experiments at 55 GPa were completed on one subsample, and a second subsample was heated in an evacuated quartz tube at 1000 °C for 170 h. A third subsample was maintained as a control. Samarium‐neodymium, Rb‐Sr, ²³⁸U‐²⁰⁶Pb, and ²⁰⁶Pb‐²⁰⁷Pb isotopic analyses were completed on mineral fractions (leached and unleached), leached whole rocks, and complementary acid leachates. Disturbance in the shocked and heated samples was evaluated through comparison of their isochron diagrams with those of the control sample. The Sm‐Nd isotope system was the least disturbed, the Rb‐Sr isotope system was more disturbed, and the ²³⁸U‐²⁰⁶Pb and ²⁰⁶Pb‐²⁰⁷Pb isotope systems were the most disturbed by shock and annealing. Samples that experienced extended heating demonstrated greater isotopic disturbances than shocked samples. In some cases, the true crystallization age was preserved, and in others, age information was degraded or destroyed. In no case did the experiments generate isochrons that maintained linearity while being rotated or completely reset. Although our results show that neither experimental shock nor thermal metamorphism alone can account for the discordant ages represented by different isotope systems in some Martian meteorites, we postulate that shock metamorphism may render a meteorite more susceptible than its unshocked counterpart to subsequent disturbance during extended impact‐related heating or aqueous alteration. The combination of these processes may result in the disparate chronometric information preserved in some meteorites.     

Laboratory experiments bearing on the origin and evolution of olivine‐rich chondrules

Abstract– Evaporation rates of K₂O, Na₂O, and FeO from chondrule‐like liquids and the associated potassium isotopic fractionation of the evaporation residues were measured to help understand the processes and conditions that affected the chemical and isotopic compositions of olivine‐rich type IA and type IIA chondrules from Semarkona. Both types of chondrules show evidence of having been significantly or totally molten. However, these chondrules do not have large or systematic potassium isotopic fractionation of the sort found in the laboratory evaporation experiments. The experimental results reported here provide new data regarding the evaporation kinetics of sodium and potassium from a chondrule‐like melt and the potassium isotopic fractionation of evaporation residues run under various conditions ranging from high vacuum to pressures of one bar of H₂+CO₂, or H₂, or helium. The lack of systematic isotopic fractionation of potassium in the type IIA and type IA chondrules compared with what is found in the vacuum and one‐bar evaporation residues is interpreted as indicating that they evolved in a partially closed system where the residence time of the surrounding gas was sufficiently long for it to have become saturated in the evaporating species and for isotopic equilibration between the gas and the melt. A diffusion couple experiment juxtaposing chondrule‐like melts with different potassium concentrations showed that the diffusivity of potassium is sufficiently fast at liquidus temperatures (D_K > 2 × 10^?4cm² s^?1 at 1650 °C) that diffusion‐limited evaporation cannot explain why, despite their having been molten, the type IIA and type IA chondrules show no systematic potassium isotopic fractionation.     

Jupiter's atmospheric temperatures: From Voyager IRIS to Cassini CIRS

Retrievals performed on Cassini Composite Infrared Spectrometer data obtained during the distant Jupiter flyby in 2000/2001 have been used to generate global temperature maps of the planet in the troposphere and stratosphere, but to higher latitudes than were shown previously by Flasar et al. [Flasar, F.M., 39 colleagues, 2004a. Nature 427, 132-135; Flasar, F.M., 44 colleagues, 2004b. Space Sci. Rev. 115, 169-297]. Similar retrievals were performed on Voyager 1 IRIS data to provide the first detailed IRIS map of the stratosphere, and high latitudes in the troposphere. Thermal winds were calculated for each data set and show strong vertical shears in the zonal winds at low latitudes, and meridional temperature gradients indicate the presence of circumpolar jets, as well. The temperatures retrieved from the two spacecraft were also compared with yearly ground-based data obtained over the intervening two decades. Tropospheric temperatures reveal gradual changes at low latitudes, with little obvious seasonal or short-term variation [Orton et al., 1994. Science 265, 625-631]. Stratospheric temperatures show much more complicated behavior over short timescales, consistent with quasi-quadrennial oscillations at low latitudes, as suggested in prior analyses of shorter intervals of ground-based data [Orton et al., 1991. Science 252, 537-542; Friedson, A.J., 1999. Icarus 137, 34-55]. A scaling analysis indicates that meridional motions, mechanically forced by wave or eddy convergence, play an important role in modulating the temperatures and winds in the upper troposphere and stratosphere on seasonal and shorter timescales. At latitudes away from the equator, the mechanical forcing can be derived simply from a temporal record of temperature and its vertical derivative. Ground-based observations with improved vertical resolution and/or long-term monitoring from spacecraft are required for this purpose, though the Voyager and Cassini data given indications that the magnitude of the forcing is very small.