Isotopic composition of formation waters from deep drillings in southern Israel

Formation water samples from deep drillings in southern Israel fall into three regional groups, each of which shows distinct chemical and isotopic characteristics. Waters from the Mediterranean coastal plain appear to be of marine lagoonal origin; some of these brines are associated with occurrences of oil. In the mountain region the top part of the sedimentary sequence has been flushed by fresher waters, apparently during Pleistocene time. In Jurassic and deeper-lying formations one encounters concentrated brines of seawater origin, with low Na/Ca ratios, which have undergone a process of ultrafiltration. In the Rift Valley proper, magnesium-rich brines have invaded the deeper formations, and are evidently of continental lake origin.The absence of oil occurrences in association with the CaCl₂ brines of the inland locations is interpreted as being due mainly to loss of oil as a result of the tectonic events associated with the formation of the Jordan Rift Valley.     

Asphalts, heavy oils, ozocerite and gases in the Dead Sea Basin

Solid, liquid and gaseous hydrocarbons occur throughout the Dead Sea Basin (Israel and Jordan) both in surface exposures and in drillings. The unaltered asphalts and heavy oils are characterized by very high sulfur content (ca. 11%) with δ³⁴S = +5% and δ¹³C = −28% to −29%, low content of n-paraffins, pristane to phytane ratio of 0.5 and by containing almost exclusively VO-porphyrins. The distribution of n-paraffins in samples from deep sources shows a smooth enveloped miximizing at C_15–20. Surface and shallow samples show clear evidence of biodegradation. The ozokerite, known only from the east side of the basin, is composed primarily of long chain n-paraffins with a maximum at C₃₉. The gases known from the southern margin of the basin are composed mostly of methane.The source for the bitumens is unknown. Two hypotheses are discussed. The first is that the asphalts and heavy oils represent an alteration products of crude oil which migrated into the basin or which might have been generated in the basin itself. The second hypothesis favors an origin from low temperature alteration of organic matter from a thermally immature source.     

Soil respiration under three different land use types in a tropical mountain region of China

Soil respiration (SR) Wis one of the largest contributors of terrestrial CO_2 to the atmosphere.Environmental as well as physicochemical parameters influence SR and thus, different land use practices impact the emissions of soil CO_2. In this study, we measured SR, bi-monthly, over a one-year period in a terrace tea plantation, a forest tea plantation and a secondary forest, in a subtropical mountain area in Xishuangbanna, China. Along with the measurement of SR rates, soil characteristics for each of the land use systems were investigated. Soil respiration rates in the different land use systems did not differ significantly during the dry season, ranging from2.7±0.2 μmol m~(-2) s~(-1) to 2.8±0.2 μmol m~(-2) s~(-1). During the wet season, however, SR rates were significantly larger in the terrace tea plantation(5.4±0.5 μmol m~(-2)s~(-1)) and secondary forest(4.9±0.4 μmol m~(-2)s~(-1)) than in the forest tea plantation(3.7±0.2 μmol m~(-2) s~(-1)).This resulted in significantly larger annual soil CO_2 emissions from the terrace tea and secondary forest,than from the forest tea plantation. It is likely that these differences in the SR rates are due to the 0.5times lower soil organic carbon concentrations in thetop mineral soil in the forest tea plantation, compared to the terrace tea plantation and secondary forest.Furthermore, we suggest that the lower sensitivity to temperature variation in the forest tea soil is a result of the lower soil organic carbon concentrations. The higher SR rates in the terrace tea plantation were partly due to weeding events, which caused CO_2 emission peaks that contributed almost 10% to the annual CO_2 flux. Our findings suggest that moving away from heavily managed tea plantations towards low-input forest tea can reduce the soil CO_2 emissions from these systems. However, our study is a casestudy and further investigations and upscaling are necessary to show if these findings hold true at a landscape level.     

Semi-structured interviews on disaster and emergency preparedness for people with disabilities in two states in Mexico

Natural Hazards - When a disaster occurs, people with disabilities are at a higher risk to adverse health outcomes due to inadequate access to resources, high levels of exposure to hazards, and an...     

Formation processes of cemented features in karstic cave sites revealed using stable oxygen and carbon isotopic analyses: A case study at middle paleolithic Amud Cave,Israel

Hearths are important archaeological features, serving to infer past practices related to hominin subsistence and social behaviors. The identification of hearths is not always straightforward due to post‐depositional processes. In karstic cave environments in particular it is not always easy to distinguish, in the field or in the laboratory, between geogenic and anthropogenic cemented features because both are composed of calcite. Here we present a novel study in which bulk oxygen and carbon isotopic analyses were used in order to unequivocally identify anthropogenic calcite derived from hearths in the Neanderthal site of Amud Cave (Israel). We demonstrate that the isotopic composition of wood ash is distinctively different from that of geogenic calcite. The linear relationship observed between carbon and oxygen isotopic compositions of the various sediment types in Amud Cave is interpreted as a mixing line between wood ash and geogenic calcite, thus enhancing our understanding of the origins of sedimentological variability at the site and showing that not all of the cemented sediments in Amud Cave should be regarded as hearths. Our study suggests that the relative abundance of validated hearths in the various areas of the cave may be associated with Neanderthal use of space in Amud Cave. © 2008 Wiley Periodicals, Inc.     

Age and geochemistry of Karoo dolerite dykes from northeast Botswana

The Botswana Dyke Swarm is a prominent 800 km long and 100 km wide feature on aeromagnetic maps of southern Africa, but little has been published on its exact age or geochemical composition. New age, trace element and isotope data for this dyke swarm show that is magmatism is indistinguishable from Karoo continental flood basalts. Ar/Ar dating gives an age of 178.9 ± 1.4 Ma. Both high Ti-Zr and low Ti-Zr dolerites occur, but the high Ti-Zr rocks appear to be the dominant type of magmatism. Low Ti-Zr mafic rocks have isotopic and trace element characteristics similar to a combination of a normal mid-ocean ridge basalt source with sedimentary and fluid-enriched components, which are thought to reside in the sub-continental lithospheric mantle. A lithospheric component seen in the high Ti-Zr mafic rocks is similar to that in nephelinites from Zimbabwe.     

Timing of reproduction of a cold desert viperid snake from North America,the Great Basin rattlesnake (Crotalus lutosus)

In this study, we examined the reproductive tracts of preserved specimens of the Great Basin rattlesnake (Crotalus lutosus) to investigate the reproductive strategies used by the only species of rattlesnakes widely occurring in a cold desert. The vitellogenic cycle of female rattlesnakes spanned over two consecutive years: females started vitellogenesis in late spring/early summer, and ovulated in the summer of the next year. This contrasts with the female reproductive cycle of other rattlesnake species from warmer regions of North America, which typically initiate vitellogenesis in summer/fall, and ovulate in late spring of the next year. On the other hand, the reproductive cycle of male C. lutosus conformed well to those described for other rattlesnakes; that is, testes were active (i.e., sperm formation) in summer. The sexual segments of the kidneys of males were hypertrophied in summer, suggesting an unimodal summer mating season. Our findings suggests that the relatively short active season (i.e., 4–5 months) experienced by these snakes in the Great Basin of North America has implications for the timing of female reproductive events, such as an early onset of vitellogenesis, a late time of ovulation, and possibly a restricted period for giving birth.     

Paleolithic burnt bone horizons from the Swabian Jura: Distinguishing between in situ fireplaces and dumping areas

Hohle Fels Cave is one of several Upper Paleolithic sites on the eastern extension of the Swabian Alb in southwestern Germany. Several phases of excavations have been conducted since 1870. The archaeological inventories comprise a broad range of artifacts produced from stone, bone, teeth, ivory, and antler. The site has also yielded Paleolithic rock art, sculpture, and engravings. The Pleistocene inventories unearthed so far belong to the Magdalenian, Gravettian, and Aurignacian; Middle Paleolithic horizons may well be uncovered as excavations continue. The chronology of three main occupation phases has been established with numerous ¹⁴C measurements. The Magdalenian dates to about 13,000 yr B.P., and the richest Gravettian deposit contains a burnt bone‐layer extending over ca. 12 m² that dates to about 29,000 yr B.P. The underlying Aurignacian horizons predate 30,000 yr B.P. The Gravettian burnt bone layer (archaeological layer IIcf) is a key horizon because of its distinct composition and color and its large horizontal extension. Layer IIcf has been examined using a combination of analytical techniques including micromorphological analysis of thin sections with polarizing light microscopy and scanning electron microscopy for fabric and identification of mineral and biogenic constituents. The bone mineral composition was analyzed by Fourier transform infrared spectroscopy (FTIR) and electron probe microanalytical techniques. These investigations in tandem with the field observations indicate intense burning of bones as fuel. The micromorphological and contextual archaeological data suggest that layer IIcf is a secondary dump rather than an in situ accumulation. This deposit and other Paleolithic burnt deposits in the Swabian Jura appear to reflect intense periods of winter occupation in these caves. © 2003 Wiley Periodicals, Inc.     

Petrographic thin sections of archaeologial sediments: A new method for paleobotanical studies

The use of petrographic thin sections to examine archaeological sediments has centered on the study of detrital and chemical components of the material. There has been relatively little effort made to study botanical remains—particularly charcoal—with this technique. This paper illustrates that millimeter-size or even smaller fragments examined in undisturbed, artificially indurated samples, which normally would escape collection with standard flotation and sieving techniques, can furnish significant paleobotanical information about the types of vegetal matter found in a site. Samples from cave sediments in Israel and an open-air site in Canada are presented. © 1994 John Wiley & Sons, Inc.