Channel systems and lobe construction in the Mississippi Fan

Morphological features on the Mississippi Fan in the eastern Gulf of Mexico were mapped using GLORIA II, a long-range side-scan sonar system. Prominent is a sinuous channel flanked by well-developed levees and occasional crevasse splays. The channel follows the axis and thickest part of the youngest fan lobe; seismic-reflection profiles offer evidence that its course has remained essentially constant throughout lobe development. Local modification and possible erosion of levees by currents indicates a present state of inactivity. Superficial sliding has affected part of the fan lobe, but does not appear to have been a factor in lobe construction.     

Seasonal Migrant Labor in the Forest Industry of the Southeastern United States: The Impact of H-2B Employment on Guatemalan Livelihoods

Migrant labor is a global phenomenon and remittances of migrant workers from non-industrial nations can play an important role in improving quality of life at family, community, and national levels. We focus on workers from Guatemala who obtain visas from the United States (US) Department of Immigration’s H-2B program that allow them to spend six or seven months a year planting and maintaining pine plantations in the southeastern US. Forestry is economically important in this region and the industry has come to depend on migrant labor. Our specific interest is how the H-2B program affects livelihood strategies of these workers, their families, and their communities. Based on primary data from 49 interviews conducted in eight Guatemalan communities, we explain motivations to engage in seasonal migration and positive changes brought about by the H-2B program in nutrition, housing, healthcare and long-term investments in agricultural lands, microenterprise development, education, and family stability.     

Chronic toxicity of ocean-dumped pharmaceutical wastes to the marine amphipod Amphithoe valida

The toxic effects of ocean-dumped pharmaceutical wastes on a marine amphipod Amphithoe valida increased with increasing duration of exposure and waste concentration. Amphipods chronically exposed to waste concentrations ≥ 1% had lower survival rates and reduced fecundity when compared to control groups. The parent amphipods exposed to 3% waste had 100% mortality by week 3, while those exposed to ≤ 2% waste were able to survive over 2 months. Larvae (F₁) of the treated amphipods survived shorter periods, 6 weeks for the 2% and 13 weeks for the 1% group. The total progeny produced by the treated amphipods (20/treatment) during the experiment dropped from 89 (F₁) to 20 (F₂) for the 1%, and from 26 (F₁) to 1 (F₂) for the 2% group. No offspring were recorded for amphipods exposed to 3% waste. For the corresponding period, the controls yielded 196 and 99 larvae respectively.     

Premier Apport de la Geochimie des Isotopes du Soufre à la Comprehension de la Genese des Mineralisations Pyriteuses de la Province de Huelva (Espagne) par

Sans résuméCe travail a pu être réalisé grâce à une subvention de la D.G.R.S.T.     

East Pacific Rise at latitude 21°N: isotopic composition and origin of the hydrothermal sulphur

The sulphur isotope composition of 16 pyrite and chalcopyrite samples from recent sulphide deposits (“Cyana”—project RITA) and active sulphide mineralisation (“Alvin”—project RISE) associated with hydrothermal sources at 380±30°C on the East Pacific Rise at latitude 21°N have been measured. The³⁴S/³²S ratios are relatively uniform and essentially identical for both sites: δ³⁴S=+1.4to3.0%. (CDT), mean +2.1‰. The sulphides were analysed after the majority of the very numerous micro-inclusions of anhydrite had been removed.Two independent physico-chemical analyses of the data demonstrate that about 90% of the sulphur was leached from the basaltic host rocks by the circulating seawater-hydrothermal fluids.