Oceanic Residence Times of Dissolved Beryllium and Aluminum Deduced from Cosmogenic Tracers 10Be and 26Al

A geochemical analogy between the metal sources in Kuwait Bay and territorial sea water of Kuwait

The sea water serves as a source for desalination and shelter for dependent biota. To understand the sources of metal in Kuwait Bay and the open sea, samples were collected and analyzed for metals like B, Li, Sr, Hg, Pb, Ba, Fe, Zn, Mn, Be, Cd, Co, Cr, Ni, Se, V, Al, Mo, and As. The comparison of Bay and Seawater shows that most of the metals were higher in sea water. Samples were collected in two different transects in the territorial sea water (TSW), the northern, and the southern transects. The heavy metal evaluation index and degree of contamination calculated for Bay and TSW show that they are contaminated, and the degree was higher in TSW. The variation of metal concentration along the transects in TSW reflects three different behaviors; (1) few metals decrease from the shore, (2) few increases from the shore, and (3) others show no significant trend. The statistical analysis of the data shows a representation of five factors for bay water and six for TSW indicating the complexity in sources of metal in TSW. The analysis infers the metal contamination due to petroleum products, and oxidation-reduction cycles are predominant in TSW. But, tidal influence along with dustfall plays a key role in the metal contamination of bay waters. Apart from these, desalination rejects and domestic sewage effluents are common sources contributing metals to both the environment. It is also observed that the suspended sediments play a significant role in the leaching, adsorption, and distribution of metals. The extraneous process has a predominant control over the distribution of the metals in TSW than the Bay.

Cosmogenic nuclide dating of Sahelanthropus tchadensis and Australopithecus bahrelghazali: Mio-Pliocene hominids from Chad

Ages were determined at two hominid localities from the Chad Basin in the Djurab Desert (Northern Chad). In the Koro Toro fossiliferous area, KT 12 locality (16 degrees 00'N, 18 degrees 53'E) was the site of discovery of Australopithecus bahrelghazali (Abel) and in the Toros-Menalla fossiliferous area, TM 266 locality (16 degrees 15'N, 17 degrees 29'E) was the site of discovery of Sahelanthropus tchadensis (Toumaï). At both localities, the evolutive degree of the associated fossil mammal assemblages allowed a biochronological estimation of the hominid remains: early Pliocene (3-3.5 Ma) at KT 12 and late Miocene ( approximately 7 Ma) at TM 266. Atmospheric (10)Be, a cosmogenic nuclide, was used to quasicontinuously date these sedimentary units. The authigenic (10)Be/(9)Be dating of a pelite relic within the sedimentary level containing Abel yields an age of 3.58 +/- 0.27 Ma that points to the contemporaneity of Australopithecus bahrelghazali (Abel) with Australopithecus afarensis (Lucy). The 28 (10)Be/(9)Be ages obtained within the anthracotheriid unit containing Toumaï bracket, by absolute dating, the age of Sahelanthropus tchadensis to lie between 6.8 and 7.2 Ma. This chronological constraint is an important cornerstone both for establishing the earliest stages of hominid evolution and for new calibrations of the molecular clock.