Distribution of moderately volatile trace elements in fine-grained chondrule rims in the unequilibrated CO3 chondrite, ALH A77307

The concentrations of Ni, Cu, Zn, Ga, Ge, and Se in five, fine-grained chondrule rims in the highly unequilibrated CO3 chondrite ALH A77307 (3.0) have been determined for the first time by synchrotron X-ray fluorescence (SXRF) microprobe at Brookhaven National Laboratory. These elements are especially useful for tracing the role of condensation and evaporation processes which occurred at moderate temperatures in the solar nebula. Understanding the distribution of moderately volatile elements between matrix and chondrules is extremely important for evaluating the different models for the volatile depletions in chondritic meteorites. The data show that the trace element chemistry of rims on different chondrules is remarkably similar, consistent with data obtained for the major and minor elements by electron microprobe. These results support the idea that rims are not genetically related to individual chondrules, but all sampled the same reservoir of homogeneously mixed dust. Of the trace elements analyzed, Zn and Ga show depletions relative to CI chondrite values, but in comparison with bulk CO chondrites all the elements are enriched by approximately 1.5 to 3.5 x CO. The abundance patterns for moderately volatile elements in ALH A77307 chondrule rims closely mimic those observed in the bulk chondrite, indicating that matrix is the major reservoir for these elements. The close matching of the patterns for the volatile depleted bulk chondrite and enriched matrix is especially striking for Na, which is anomalously depleted in ALH A77307 in comparison with average CO chondrite abundances. The depletion in Na is probably attributable to the effects of leaching in Antarctica. With the exception of Na, the volatile elements show a relatively smooth decrease in abundance as a function of condensation temperature, indicating that their behavior is largely controlled by their volatility.     

Integrated chemostratigraphy and biostratigraphy of the Windermere Supergroup, northwestern Canada: implications for Neoproterozoic correlations and the early evolution of animals

The thick, richly fossiliferous succession of the upper Windermere Supergroup, Mackenzie Mountains, northwestern Canada, provides a test of integrated biostratigraphic and chemostratigraphic frameworks in terminal Proterozoic correlation. The C- and Sr-isotopic abundances of lower Keele Formation carbonates approximate those for other pre-Varanger samples, confirming that the simple disc-like fossils of the underlying Twitya Formation predate all known diverse Ediacaran faunas. "Tepee" and Sheepbed carbonates record strong post-glacial isotopic excursions; in contrast, delta13C values for Gametrail through Risky carbonates vary only within the narrow range of about +l% to +2%. A second negative excursion occurs in Ingta Formation carbonates that immediately underlie the paleontologically determined Precambrian-Cambrian boundary. The upper Windermere profile as a whole compares closely with curves determined for other terminal Proterozoic successions. The lowermost diverse Ediacaran assemblages in the Sheepbed Formation correlate chemostratigraphically with the oldest fauna in Namibia, but the two assemblages differ in taxonomic composition. Blueflower assemblages correlate both chemostratigraphically and taxonomically with faunas from Australia, China, Siberia, and elsewhere. Increasing data support the hypothesis that paleontological and geochemical data together provide a reliable means of correlating terminal Proterozoic sedimentary rocks throughout the world.     

Patterns of literacy in the People's Republic of China

The recent publication of data from the 1982 census permits an assessment of the patterns, progress and problems of illiteracy in China. Educational progress, since the communists came to power in 1949, has been particularly impressive, especially in relation to the low levels of income within the People's Republic. Nevertheless, nearly a third of the country's population are still unable to read and write and major variations in literacy exist between the developed and less developed regions, between men and women, between the urban and rural areas, between the various age groups and among the many ethnic groups that constitute the People's Republic of China. Among the most favoured people and places, literacy rates exceed 90% but among the most disadvantaged groups, retired women in rural areas for example, levels of literacy fall below 3%. Proposed educational reforms, targeted to provide nine years of compulsory education, offer the potential for boosting literacy levels and breaking the bondage of ignorance. However, such proposals are being undermined by the recent economic reforms in rural China. By stressing the value of labour, including child labour, the agricultural responsibility system has generated a surprising decline in school attendance which may jeopardise future improvements in literacy, particularly so among the poorer people in the poorer areas of China.     

发展中国家的地质调查机构:援助战略(一)

一、引论 对发展中国家进行技术和财政援助的施援国作出了很大的努力,以帮助受援国建立起适应经济发展的基础设施。在许多地区,这种开发援助形成了明显易见和可交付使用的设施,如公路、铁路、港口、发电站、医院、学校和房舍。不太显见的是由科学和技术知识构成的基础层,而它是健全的国家发展计划的基本     

Habitat associations of floating debris and marine birds in the North East Pacific Ocean at coarse and meso spatial scales

While many surface foraging seabirds ingest plastic, the spatial overlap of these far-ranging predators with debris aggregations at-sea is poorly understood. We surveyed concurrent distributions of marine birds and debris along a 4400 km cruise track within a debris accumulation area in the North East Pacific Ocean using line and strip transect methods. Analysis of debris and bird distributions revealed associations with oceanographic and weather variables at two spatial scales: daily surveys and hourly transects. Hourly bird abundance (densities; 0-9 birds km⁻²) was higher in lower wind and shallower water. Hourly debris abundance (densities; 0-15,222 pieces km⁻²) was higher in lower wind, higher sea-level atmospheric pressure and deeper water. These results suggest that debris and seabird abundance and community structure are influenced by similar environmental processes, but in opposing ways, with only three far-ranging seabird species (Black-footed Albatross, Cook’s Petrel and Red-tailed Tropicbird) overlapping with high debris concentrations over meso-scales.     

Atmospheric lead fallout over the last century recorded in Gulf of Lions sediments (Mediterranean Sea)

Six marine sediment cores from the Gulf of Lions continental slope (700-1700 m water depth) were analyzed for stable lead isotopes and (210)Pb geochronology in order to reconstruct lead atmospheric fallout pattern during the last century. The detrital lead contribution is 25 microg g(-1) and the mean sediment anthropogenic inventory is 110+/-7 microg cm(-2), a little bit higher than atmospheric deposition estimate. Anthropogenic lead accumulation in sediments peaked in early 1970s (1973+/-2) in agreement with lead emissions features. For the period 1986-1997, the sediment signal also reflect the decrease of atmospheric lead described by independent atmospheric fallout investigations. The anthropogenic Pb deposition in the late 1990s was similar to the 1950s deposition, attesting thus of the output of European environmental policies.