Mycological evidence of coprophagy from the feces of an Alaskan Late Glacial mammoth

Dung from a mammoth was preserved under frozen conditions in Alaska. The mammoth lived during the early part of the Late Glacial interstadial (ca 12,300 BP). Microfossils, macroremains and ancient DNA from the dung were studied and the chemical composition was determined to reconstruct both the paleoenvironment and paleobiology of this mammoth. Pollen spectra are dominated by Poaceae, Artemisia and other light-demanding taxa, indicating an open, treeless landscape (‘mammoth steppe’). Fruits and seeds support this conclusion. The dung consists mainly of cyperaceous stems and leaves, with a minor component of vegetative remains of Poaceae. Analyses of fragments of the plastid rbcL gene and trnL intron and nrITS1 region, amplified from DNA extracted from the dung, supplemented the microscopic identifications. Many fruit bodies with ascospores of the coprophilous fungus Podospora conica were found inside the dung ball, indicating that the mammoth had eaten dung. The absence of bile acids points to mammoth dung. This is the second time that evidence for coprophagy of mammoths has been derived from the presence of fruit bodies of coprophilous fungi in frozen dung. Coprophagy might well have been a common habit of mammoths. Therefore, we strongly recommend that particular attention should be given to fungal remains in future fossil dung studies.     

Aerosol-Cloud-Precipitation Interactions in a Closed-cell and Non-homogenous MBL Stratocumulus Cloud

A closed-cell marine stratocumulus case during the Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA) aircraft field campaign is selected to examine the heterogeneities of cloud and drizzle microphysical properties and the aerosol-cloud-precipitation interactions. The spatial and vertical variabilities of cloud and drizzle microphysics are found in two different sets of flight legs: Leg-1 and Leg-2, which are parallel and perpendicular to the cloud propagation, respectively. The cloud along Leg-2 was close to adiabatic, where cloud-droplet effective radius and liquid water content linearly increase from cloud base to cloud top with less drizzle. The cloud along Leg-1 was sub-adiabatic with lower cloud-droplet number concentration and larger cloud-droplet effective, but higher drizzle droplet number concentration, larger drizzle droplet median diameter and drizzle liquid water content. The heavier drizzle frequency and intensity on Leg-1 were enhanced by the collision-coalescence processes within cloud due to strong turbulence. The sub-cloud precipitation rate on Leg-1 was significantly higher than that along Leg-2. As a result, the sub-cloud accumulation mode aerosols and CCN on Leg-1 were depleted, but the coarse model aerosols increased. This further leads to a counter-intuitive phenomenon that the CCN is less than cloud-droplet number concentration for Leg-1. The average CCN loss rates are ?3.89 \begin{document}$\mathrm{c}{\mathrm{m}}^{-3}\;{\mathrm{h}}^{-1}$\end{document} and ?0.77 \begin{document}$\mathrm{c}{\mathrm{m}}^{-3}\;{\mathrm{h}}^{-1}$\end{document} on Leg-1 and Leg-2, respectively. The cloud and drizzle heterogeneities inside the same stratocumulus can significantly alter the sub-cloud aerosols and CCN budget. Hence it should be treated with caution in the aircraft assessment of aerosol-cloud-precipitation interactions.     

A seismic refraction study of cretaceous oceanic lithosphere in the Northwest Pacific Basin

A seismic refraction study on old (110 Myr) lithosphere in the northwest Pacific Basin has placed constraints on crustal and uppermantle seismic structure of old oceanic lithosphere, and lithospheric aging processes. No significant lateral variation in structure other than azimuthally anisotropic mantle velocities was found, allowing the application of powerful amplitude modeling techniques. The anisotropy observed is in an opposite sense to that expected, suggesting the tectonic setting of the area may be more complex than originally thought. Upper crustal velocities are generally larger than for younger crust, supporting current theories of decreased porosity with crustal aging. However, there is no evidence for significant thickening of the oceanic crust with age, nor is there any evidence of a lower crustal layer of high or low velocity relative to the velocity of the rest of Layer 3. The compressional and shear wave velocities rule out a large component of serpentinization of mantle materials. The only evidence for a basal crustal layer of olivine gabbro cumulates is a 1.5 km thick Moho transition zone. In the slow direction of anisotropy, upper mantle velocities increase from 8.0 km s^-1 to 8.35 km s^-1 in the upper 15 km below the Moho. This increase is inconsistent with an homogeneous upper mantle and suggests that compositinal or phase changes occur near the Moho.     

Near-infrared laboratory spectra of solid H2O/CO2 and CH3OH/CO2 ice mixtures

We present near-IR spectra of solid CO₂ in H₂O and CH₃OH, and find they are significantly different from that of pure solid CO₂. Peaks not present in either pure H₂O or pure CO₂ spectra become evident when the two are mixed. First, the putative theoretically forbidden CO₂ (2ν₃) overtone near 2.134 μm (4685 cm⁻¹), that is absent from our spectrum of pure solid CO₂, is prominent in the spectra of H₂O/CO₂=5 and 25 mixtures. Second, a 2.74-μm (3650 cm⁻¹) dangling OH feature of H₂O (and a potentially related peak at 1.89 μm) appear in the spectra of CO₂-H₂O ice mixtures, but are probably not diagnostic of the presence of CO₂. Other CO₂ peaks display shifts in position and increased width because of intermolecular interactions with H₂O. Warming causes some peak positions and profiles in the spectrum of a H₂O/CO₂=5 mixture to take on the appearance of pure CO₂. Absolute strengths for absorptions of CO₂ in solid H₂O are estimated. Similar results are observed for CO₂ in solid CH₃OH. Since the CO₂ (2ν₃) overtone near 2.134 μm (4685 cm⁻¹) is not present in pure CO₂ but prominent in mixtures, it may be a good observational (spectral) indicator of whether solid CO₂ is a pure material or intimately mixed with other molecules. These observations may be applicable to Mars polar caps as well as outer Solar System bodies.     

Tracer dispersal by mid-ocean mesoscale eddies. Part I. Ensemble statistics

The rate at which, and the processes by which, a passive tracer is stirred and mixed in a turbulent mesoscale eddy field are examined for environmental parameters characteristic of a homogeneous mid-ocean region. The simulated, time-dependent eddy field is obtained by direct integration of the forced/damped barotropic vorticity equation; the dispersal of a spatially localized, instantaneous release of tracer (a “tracer spot”) within the evolving velocity field is subsequently computed from the advective-diffusive equation. An ensemble of 10 independent releases is used to determin the average spreading properties of the tracer spot.On an f-plane, the ensemble-averaged dispersal is approximately isotropic, and is associated with an effective diffusion rate substantially greater than that supported in the absence of turbulent advection. Quantitatively, the effective ensemble-averaged diffusivity is shown to be 0(UL), where U and L are characteristic velocity and length scales of the turbulent flow. This estimate is consistent with the traditional mixing length hypothesis. With the addition of β, the simulated flow field has substantial zonal anisotropy. Ensemble-averaged dispersal of tracer spots is similarly anisotropic, and the overall rate of tracer dispersal is substantially reduced over its f-plane value.Both with and without β, the initial rate at which maximum tracer concentration and total tracer variance decay are given by the approximate law exp[? αγt] where γ is the RMS rate of strain, and α is approximately constant at a value of 0.5. The heightened rate of variance loss over that associated with pure (subgridscale) diffusion is shown to be accommodated by the rapid transfer of tracer variance from the largest to the shortest scale tracer features, that is, by the rapid sharpening of tracer gradients by turbulent advection. A detailed examination of the dispersal of individual tracer realizations, and the associated question of tracer streakiness, is given in part II of this work (Keffer and Haidvogel, in preparation).     

TOPOGRAPHIC SHADING AND GEOGRAPHICAL PATTERNS OF DIRECT SOLAR RADIATION IN MOUNTAINOUS REGIONS*

Topographic shading curtails the period and complicates the geographic patterns of insolation in mountainous areas. Maps derived from oblique aerial photographs of shadow lines cast by the irregular, mountainous east horizon in Provo, Utah are used as a case study to illustrate an alternative to existing techniques of solar radiation data collection. For study areas of several hundred square kilometers, this method may be superior in resolution and at the same time more error free and economically feasible than other methods. Measurement of solar inputs received at sample stations scattered through the mapped area show that the phenomenon of topographically delayed sunrise has a distinct effect on daily totals of radiation in the manner suggested by the maps.     

Archipelagos and the law of the sea: Island straits states or island-studded sea space?

At first sight, the regime suggested for archipelagos at UNCLOS seems to recognize to a large extent the concept of the archipelago as a single unit of islands and water. The author examines closely whether in fact the archipelagic states' view of their maritime jurisdiction has been upheld, or whether the negotiations have led to a position based on traditional concepts of law of the sea. The archipelago doctrine and interests underlying it, opposition to it, and the considerations by the international legal community are discussed. Finally, developments on archipelagos in the Seabed Committee and UNCLOS III are traced in order to understand the language of the proposed archipelagic regime.     

Minor constituents in the atmosphere of Jupiter

New spectra of Jupiter in the region 0.93–1.63 are presented. Laboratory comparisons of spectra of NH₃ and CH₄ permit estimates of the absorbing pathlength for various bands of these two gases. Abundances in a single transmission through the Jupiter atmosphere, above the mean reflecting level, vary from 10 to 100 m-atm for CH₄ and from 0.2–5 m-atm for NH₃, depending on the bands considered. Upper limits for other gases are derived from new laboratory spectra and comparison with the Jupiter spectra presented herein. These are as follows: C₂H₂<2 m-atm, H₂S<0.25 m-atm, HCN<0.05 m-atm, CH₃NH₂<0.02 m-atm. A table summarizing the chemical composition of Jupiter's atmosphere is presented.