Oil pollution on the Egyptian Red Sea coast

A simple weighing method using carbon tetrachloride as solvent was used to survey the dissolved hydrocarbon and tarball levels in the area of the Egyptian Red Sea coast. The area of investigation covers the coastal area from Ras-Gharib down to the port of Qosier during the period from September 1979 to February 1981. This survey confirms the presence of extensive oil pollution in the area, especially at Ras-Gharib and Ras-Shukhair. Minimum concentrations were obtained at Ghardaqa where no dissolved hydrocarbons were detected (i.e. less than 10 μg l^?1) in 1979–1980 but an increase to 20 μg l^?1 in 1981 was recorded. The high levels of pollution recorded in the southern part of the Gulf of Suez are related to the presence of the offshore oil fields, most of which are located at Ras-Gharib.     

Statistical simulations of the future 50-year statistics of cold-tongue El Niño and warm-pool El Niño

Recent extensive studies have suggested that the occurrence of warm-pool El Niño has increased since the late 1970s and will increase in future climate. Occurrence frequencies of cold-tongue and warm-pool El Niño have been investigated in the observational record (1980–2006) and in the future 50 years (2007–2056) based on 100 synthetic SST datasets with estimates of statistical confidence. In the observational record, 80% of the warm-pool El Niño occurred since 1980 over a period of 27 years; only 20% of the warm-pool El Niño occurred prior to 1980 over a period of 110 years. The 100 synthetic datasets, on average, produce 142 months of cold-tongue El Niño in 2007–2056 as opposed to an average 107 months in the same length of the observational data; this is a 20.7% increase in the occurrence of cold-tongue El Niño compared with the observational period. Warm-pool El Niño occurred for 112 months in 2007–2056 as opposed to an average occurrence of 42 months in the observational record; this is 2.5 times the occurrence frequency in the 1980–2006 period in the synthetic datasets. As a result, occurrence frequencies of cold-tongue and warm-pool El Niño in the period of 2007–2056 become quite comparable to each other in the synthetic datasets. It is expected in the next 50 years that warm-pool El Niño will be nearly as frequent as cold-tongue El Niño.     

Hydrothermal jarosite and hematite in a pyroxene-hosted melt inclusion in martian meteorite Miller Range (MIL) 03346: Implications for magmatic-hydrothermal fluids on Mars

Low-temperature aqueous processes have been implicated in the generation of jarosite and hematite on the martian surface, but little is known regarding the role that high-temperature magmatic fluids may have played in producing similar assemblages on Mars. We have identified jarosite and hematite in a clinopyroxene-hosted melt inclusion in martian meteorite MIL 03346 that shows evidence of having been hydrothermally precipitated. In addition to jarosite and hematite, the melt inclusion contains titanomagnetite, pyrrhotite, potassic-chlorohastingsite, an iron-rich silicate glass and possibly goethite. These phases were identified and characterized using scanning electron microscopy (SEM), con-focal Raman-spectroscopy and electron probe microanalysis (EPMA).Based on observed textural relationships and the compositions of the hosted phases, we report that the jarosite-bearing melt inclusion in MIL 03346 has recorded a fluid-rich history that began in the magmatic stage and continued to low-temperatures. This history begins at entrapment of a volatile-rich silicate melt that likely reached fluid-saturation after only minor crystallization within the melt inclusion. This fluid, rich in chlorine, reacted with surrounding silicate material to produce the potassic-chlorohastingsite. As cooling proceeded, the liquid phase eventually became more oxidized and reacted with the pyrrhotite. Sulfide oxidation resulted in SO₄²⁻ formation and concomitant acid production, setting the stage for jarosite formation once the fluid cooled beyond the upper thermal stability of jarosite (∼200 °C). As the fluid cooled below 200 °C, jarosite continued to precipitate with hematite and/or goethite until equilibrium was established or reactions became kinetically unfavorable.This work suggests an additional jarosite-hematite formation pathway on Mars; one that may be important wherever magmatic-hydrothermal fluids come into contact with primary sulfide grains at the martian surface or subsurface. Moreover, hydrothermal fluids rich in chlorine, sulfur, and iron are important for ore-forming processes on Earth, and their indirect identification on Mars may have important implications for ore-formation on Mars.     

Scattering of obliquely incident water waves by partially reflecting non-transmitting breakwaters

In the present paper, analytic solutions are derived for scattering of water waves obliquely incident to a partially reflecting semi-infinite breakwater or breakwater gap. In order to examine the correctness of the derived solutions, they are compared with the solutions derived by McIver (1999) and Bowen and McIver (2002) for a semi-infinite breakwater and a breakwater gap, respectively, in the case of perfect reflection. The derived analytic solutions are used to investigate the effect of reflection coefficient of the breakwater and wave incident angle upon the tranquility at harbor entrance. The tranquility is deteriorated by the reflected waves as the reflection coefficient increases and as waves are incident more obliquely.     

YORP torque as the function of shape harmonics

The second-order analytical approximation of the mean Yarkovsky–O'Keefe–Radzievskii–Paddack (YORP) torque components is given as an explicit function of the shape spherical harmonics coefficients for a sufficiently regular minor body. The results are based upon a new expression for the insolation function, significantly simpler than in previous works. Linearized plane-parallel model of the temperature distribution derived from the insolation function allows us to take into account a non-zero conductivity. Final expressions for the three average components of the YORP torque related with rotation period, obliquity and precession are given in a form of the Legendre series of the cosine of obliquity. The series have good numerical properties and can be easily truncated according to the degree of the Legendre polynomials or associated functions, with first two terms playing the principal role.     

The petrogenetic association of carbonatite and alkaline magmatism: constraints from the Masfut-Rawda Ridge, Northern Oman Mountains

Summary ?A new occurrence of carbonatites associated with intrusive ijolite and syenite has been discovered within the Hawasina Complex underlying the Semail Ophiolite Complex at the southern part of the Rawda-Masfut ridge, Northern Oman Mountains. The carbonatites occur as dikes and sills with lengths of several hundreds of meters and range in composition from calciocarbonatites to ferruginous calciocarbonatites. The carbonatites intruded the ijolite and the associated radiolarian cherts of the Early Cretaceous Sid’r Formation. The close spatial association of carbonatite, ijolite, syenite and radiolarian cherts along with geological, petrographical and geochemical data indicates that these rocks are of intra-oceanic origin. Petrological and field relationships between the carbonatite and associated alkaline silicate intrusives from the Masfut area are consistent with the carbonatites being generated as derivative magmas through liquid immiscibility. They appear to represent magmas related to the volcanism associated with regional crustal extension that preceded the genesis of the Semail Ophiolite. Received April 19, 2001; revised version accepted February 18, 2002     

Methodological frameworks for the geography of organizations

In this paper, we present three methodological frameworks for the geographic study of organizations. These are situated within three meta-theoretical perspectives in human geography: spatial science, critical realism, and post-structuralism. Each framework offers a different theorization of organizations, and each prompts different research questions that can be used to guide their geographic study. The research questions we offer are general, and are pertinent to all types of organizations. To supplement the methodological contributions of this paper, we suggest how each of these frameworks might inform empirical investigations of Appalshop, a media arts organization located in Whitesburg, Kentucky.     

Glaciodynamically upthrusted bands of englacially transported debris in the Pleistocene of central Poland

Two kinds of buried structures are described from Dzirżenin, north-east of Warsaw, where they occur within a glaciofluvial landform: (1) narrow till ridges, showing vertically oriented structures, excavated from stratified gravel and sands; and (2) a narrow vertical zone of massive gravelly/sandy material, involving vertically oriented lens-like layers composed of massive sand with pebbles, or of diamicton. The gravelly/sandy zone is also closely surrounded by stratified glaciofluvial sediments. In spite of their vertical position and internal deformation, the till ridges and gravelly/sandy zone show non-tectonic contacts with the surrounding, stratified, undisturbed sediments. The glaciofluvial sediments that occur immediately next to the structures under discussion are characterized by the occurrence of comparatively coarse material and interbeddings of diamicton, which wedge out away from these structures. The gravelly/sandy zone separates different kinds of water-laid deposits. The buried structures are interpreted as former debris-laden bands, thrust upwards within the frontal part of the ice sheet and then transformed into still-frozen debris ridges projecting over the already dead ice. Further melting of the decaying ice resulted in abundant glaciofluvial sedimentation, and the debris ridges also supplied material for the deposition of the neighbouring stratified deposits. One of the ridges separated different glaciofluvial environments. The glaciofluvial sediments completely buried the ice-cemented ridges, which were finally transformed by a melting-out process into the till ridges and the gravelly/sandy zone. The former are interpreted as having been transformed from upturned debris-laden bands with a high concentration of debris or from the bands composed of frozen-up sediment slabs. The gravelly/sandy zone is interpreted as having (most probably) been deposited from upturned bands characterized by a lesser concentration of debris.     

Speleothem evidence for late Holocene climate variability and floods in Southern Greece

We present stable isotope data (δ¹⁸O, δ¹³C) from a detrital rich stalagmite from Kapsia Cave, the Peloponnese, Greece. The cave is rich in archeological remains and there are reasons to believe that flooding of the cave has directly affected humans using the cave. Using a combination of U–Th and ¹⁴C dating to constrain a site-specific correction factor for (²³²Th/²³⁸U) detrital molar ratio, a linear age model was constructed. The age model shows that the stalagmite grew during the period from ca. 950 BC to ca. AD 830. The stable oxygen record from Kapsia indicates cyclical changes of close to 500 yr in precipitation amount, with rapid shifts towards wetter conditions followed by slowly developing aridity. Superimposed on this signal, wetter conditions are inferred around 850, 700, 500 and 400–100 BC, and around AD 160–300 and AD 770; and driest conditions are inferred to have occurred around 450 BC, AD 100–150 and AD 650. Detrital horizons in the stalagmite indicate that three major floods took place in the cave at 500 BC, 70 BC and AD 450. The stable carbon isotope record reflects changes in biological activity being a result of both climate and human activities.