The significance of Messinian occurrences of Globorotalia margaritae and Globorotalia puncticulata in Sicily

Globorotalia puncticulata and Globorotalia margaritae are critical species that define internationally recognized planktonic foraminiferal biozones in the Pliocene. These biozones are defined from stratotype sections on Sicily and their fauna are commonly considered to have been introduced to the Mediterranean after an influx of Atlantic water that terminated the late Miocene desiccation of the basin. Herein new discoveries of these species in rocks that predate the late Miocene desiccation are described. These data are supported by magneto- and lithostratigraphy that have been integrated at a single continuous section. Not only do these discoveries question the existing foraminiferal biozone stratigraphy, they also suggest new models for the dispersal of planktonic species. It is proposed that Globorotalia puncticulata and perhaps even Globorotalia margaritae evolved in the Mediterranean during earliest Messinian times (during or before chron C3Bn1n) and dispersed into the Atlantic. This suggests that a marine connection remained between the two sea areas until at least chron C3An.1n. Using the existing geomagnetic polarity time scale, these occurrences are some 2 Myr earlier than previously recorded in the Mediterranean. The distribution of G. margaritae and G. puncticulata in Mediterranean sections is likely to reflect palaeoenvironment or the preservation of deposits rather than the absolute age of the sediments.     

Evaporative weathering of petroleum residues: The age of pelagic tar

The rate of evaporative weathering of a component of crude oil residue is assumed to be proportional to its equilibrium vapor pressure and to the amount remaining in the sample. This model is tested using literature data on normal paraffin profiles of crude oil weathered artificially and gas chromatographic data on crude oil residues weathered on rocky shores. Semiquantitative agreement over the time range from 1 to 400 days is demonstrated. Application of the model to gas chromatograms of pelagic tar lumps collected at Station S near Bermuda in 1972 implies that most of these lumps were formed by fragmentation of much larger and older masses, some within less than one day of the time they were collected. The weathering of pelagic tar thus involves a great deal more physical fragmentation than was previously supposed.     

The possible connection between ionization in the atmosphere by cosmic rays and low level clouds

Recent analysis of monthly mean cloud data from the International Satellite Cloud Climatology Project uncovered a strong correlation between low cloud and the cosmic ray flux for extensive regions of the Earth. Additional data have been recently released covering the period up to September 2001 with which we have made a new study of the geographical variation of the correlation between low cloud and predicted ionization level from cosmic rays at an altitude of 2 km. When analysed globally, we find that the correlations do not correspond to the latitude variation of cosmic ray flux and they are not field significant. Nonetheless they appear to be marginally field significant over broad latitude and longitude bands with a peak positive correlation at 50 degrees North and South and a tendency to negative correlation at lower latitudes. The correlation is strongest over the North and South Atlantic. Several of these features are consistent with the predictions of the electroscavenging process.We use a simple model to calculate the climatic impact should the correlation be confirmed. We show that, under the most favorable conditions, a reduction in low cloud cover since the late 19th century, combined with the direct forcing by solar irradiance can explain a significant part of the global warming over the past century, but not all. However, this computation assumes that there is no feedback or changes in cloud at other levels.     

Changing human-environment interactions in medium mountains: the Apuseni Mts (Romania) as a case study

The study of human-environment relationships in mountain areas is important for both theoretical and practical reasons, as many mountain areas suffer similar problems, such as depopulation, unemployment and natural hazards. Medium mountains constitute a special case within mountains, because they are more populated but less attractive as tourist destinations than high mountains. In this context, the Apuseni Mts (Romania) are considered as a case study. In this paper, we apply GIS-based, quantitative methods to characterize the strength and dynamics of human-environment interactions, taking into consideration some environmental factors (elevation, relative height, slope, river distance, lithology, land cover, natural attractions) as well as historical population and recent tourism data. We found that population density has strong (r ²>0.8) relationships with all relief factors (elevation, relative height, slope, river distance), and that best-fit functions are nonlinear. We outlined the varying demographic scenarios by elevation zones and interpreted the historically switching sign of population change versus elevation relationship. We demonstrated that lithology also has an impact on the spatial distribution of population, although it is not independent from the relief effect. The land cover of the mainly cultural landscape is very strongly correlated with relief parameters (especially slope), which suggests good adaptation. We pointed out the dominance of karst objects in the natural tourism potential of the Apuseni Mts and also explored further components of real tourism (spas, heritage, towns). Finally, we concluded that the environmental settings investigated do in fact constrain the spatial framework of society, but socio-economic changes in history can be explained from the side of society, which conforms to the theory of cultural possibilism.     

Coulometric total carbon dioxide analysis for marine studies: maximizing the performance of an automated gas extraction system and coulometric detector

A global survey of the distribution of dissolved CO₂ taking advantage of sampling opportunities provided by the World Ocean Circulation Experiment: World Hydrographic Program (WOCE-WHP) is being carried out through 1995. Goals include the measurement of oceanic inorganic carbon transport and the development of a data base from which future fossil-fuel CO₂ build-up can be monitored. The analytical method selected for total carbon dioxide (C_T) is gas extraction of acidified seawater with coulometric titration of the acid formed by the resultant carbon dioxide and monoethanolamine. To combine high accuracy and precision (± 1.5 μmol/kg for C_T ≥ 2000 μmol/kg) with a high rate of analysis, we have modified an automated single-parameter system. Following prototype development between 1987 and 1990, an instrument emerged with the acronym Somma standing for single-operator multiparameter metabolic analyzer. Improved functional and operating procedures have integrated electronic calibration, CO₂ gas calibration, and sample analysis with automated pressure, temperature, and conductivity (salinity) sensing into a single convenient transportable package.     

Geochemical and hydrodynamic constraints on the distribution of trace metal concentrations in the lagoon of Nouméa, New Caledonia

Seawater samples were collected in the lagoon of Nouméa (southwest New Caledonia) along two transects from eutrophic coastal bays to the oligotrophic barrier reef. Land-based emissions to the lagoon were measured with dissolved and particulate concentrations of chromium (Cr) and nickel (Ni), used as tracers of both terrigenous and industrial (Ni ore treatment) activities, as well as dissolved and particulate concentrations of zinc (Zn), used as a tracer of urban effluents. The spatial variability of metal concentrations was related to geochemical and hydrodynamic conditions, i.e., respectively: (1) natural and anthropogenic emission sources, and chemical processes occurring in the water column; and (2) water residence times. The parameter used to describe the residence time of water masses was the local e-flushing time, i.e. the time required for a tracer mass contained within a given station to be reduced by a factor 1/e. High metal concentrations were found in coastal areas (up to 9000 ng dissolved Ni L⁻¹), and steeply decreased with distance from the coast (down to 101 ng dissolved Ni L⁻¹ near the barrier reef) to reach levels similar to those found in remote Pacific waters, suggesting a rapid renewal of waters close to the barrier. Distributions of metals in the lagoon are controlled upstream by land-based emission sources and later chemical processes. Then hydrodynamics constrain metal distributions, as shown by the observed relationship between local e-flushing times and the spatial variability of metal concentrations. In addition, a change in the direction of prevailing winds yielded a decrease of dissolved metal concentrations at the same site by a factor of 2.5 (Cr and Ni) and 2.9 (Zn). It is suggested that the residence time is a key parameter in the control of elemental concentrations in the lagoon waters, as much as land-based emission sources.     

Observation of MKN 501 at gamma-ray energies

During a balloon flight in September 1979 of the MISO low-energy -ray telescope, the BL Lac-object MkN 501 was studied in the hard X-ray range above 30 keV and in the low energy -ray range up to 19 MeV. No statistically significant X- and -ray fluxes were detected. The implications of the upper limits obtained are discussed in the light of the relativistic jet theories recently proposed.     

Evaluating the effects of catch-and-release angling on Cape stumpnose Rhabdosargus holubi in a South African estuary

Fisheries managers are increasingly promoting catch-and-release (C&R) to manage recreationally angled fish stocks. Despite this, there is a scarcity of information on the effects of C&R on estuarine-dependent species. Cape stumpnose Rhabdosargus holubi dominates the recreational fisheries catch and provides an important source of food for subsistence fishers in some temperate South African estuaries. The health and survival of R. holubi exposed to a C&R event was investigated by examining their physiological stress response (blood glucose and lactate), reflex impairment (reflex action mortality predictors [RAMP]) and short-term (12-hour) survival. Fish were captured and exposed to one of three air-exposure treatments: 0 s, 30 s or 90 s. Stress and health were measured either immediately (immediate) or one hour after (delayed) the C&R event. There was no significant difference in blood glucose between air-exposure treatments, but there was a significant difference between the mean immediate and delayed glucose levels within each treatment (F_(2,143) = 81.8, p < 0.01). In contrast, blood lactate level was significantly higher in the 90-s treatment (p < 0.05). Immediate blood lactate levels were significantly lower than the delayed samples for each treatment (F = 4.29, p = 0.02; n = 169). Although all fish exhibited at least one reflex impairment, the RAMP score was significantly higher in the 90-s air-exposure treatment (H_(2,86) = 9.73, p = 0.007). Also, RAMP scores were significantly lower in the delayed samples (p < 0.01). Although short-term mortality was relatively low (2.3%) for this species, it was highest in the 90-s treatment (7%). These results suggest that physiological stress is higher when R. holubi are exposed to longer periods of air exposure and that the physiological stress of fish subject to a C&R event is best measured after a delay.     

TRIFFID observations of the cores of the three globular clusters M15, M92 and NGC 6712

We present the results of TRIFFID simultaneous V - and B -band observations of the cores of the globular clusters M15, M92 and NGC 6712. A variability search of their dense centres was made feasible through performing post-exposure image sharpening on the images, increasing the image resolution by a factor of ∼2. The isis implementation of the image subtraction technique developed by Alard & Lupton was then used to detect flux variations in our image sets. We have obtained periods for all observable variables (in our field of view) in NGC 6712 and we have found two new RR Lyrae variables (an RRab and an RRc). We have confirmed three variables in our field of view of the M92. For M15, we detect 48 variables in our field of view, 23 of which are new discoveries. We obtain periods and amplitudes for all variables and classify new ones based on the light-curve shape, the most significant period and the mean magnitude in the V band. Among the detected RR Lyrae we find 19 RRc, 12 RRab and two RRd types. In the subsequent analysis we find a marked increase in RRc over RRab variables in the core. In a refined procedure to search for fainter objects we find no dwarf novae in our field of view of M15. Simulations performed on the data set to quantify our sensitivity to such objects indicate that an upper limit of 10 dwarf novae (at 92 per cent probability) exist in our field of view. The implications this result has on globular clusters are discussed.