University of Rennes

About: University of Rennes is a education organization based out in Rennes, France. It is known for research contribution in the topics: Population & Catalysis. The organization has 18404 authors who have published 40374 publications receiving 995327 citations.

Elemental properties, hydrology, and biology interact to shape concentration-discharge curves for carbon, nutrients, sediment, and major ions

Abstract: To investigate the prevalence and cause of concentration-discharge (C-Q) relationships for carbon, nutrients, major ions, and particulates, we analyzed 40 years of water quality data from 293 monitoring stations in France. Catchments drained diverse landscapes and ranged from 50 to 110,000 km2, together covering nearly half of France. To test for differences during low and high flows, we calculated independent C-Q slopes above and below the median discharge. We found that 84% of all catchment-element combinations were chemodynamic for at least half of the hydrograph and 60% of combinations showed non-linear C-Q curves. Only two or three of the nine possible C-Q modalities were manifest for each parameter, and these modalities were stable through time, suggesting that intrinsic and extrinsic elemental properties (e.g. solubility, reactivity, and source dynamics) set basic C-Q templates for each parameter, which are secondarily influenced by biological activity during low flows, and the interaction between hydrology and catchment characteristics at high flows. Several patterns challenged current C-Q views, including low-flow chemostasis for TSS in 66% of catchments, low-flow biological mediation of NO3- in 71% of catchments, and positive C-Q for dissolved organic carbon independent of catchment size in 80% of catchments. Efforts to reduce nutrient loading decreased phosphorus concentration and altered C-Q curves, but NO3- continued to increase. While C-Q segmentation requires more data than a single analysis, the prevalence of non-linear C-Q slopes demonstrates the potential information loss associated with linear or monotonic analysis of C-Q relationships, and conversely, the value of long-term monitoring. This article is protected by copyright. All rights reserved.

Occupation and bladder cancer among men in Western Europe.

Abstract: Objectives: We examined which occupations and industries are currently at high risk for bladder cancer in men. Methods: We combined data from 11 case–control studies conducted between 1976–1996 in six European countries. The study comprised 3346 incident cases and 6840 controls, aged 30–79 years. Lifetime occupational and smoking histories were examined using common coding. Results: Odds ratios for eight a priori defined high-risk occupations were low, and with the exception of metal workers and machinists (OR = 1.16, 95% CI = 1.02–1.32), were not statistically significant. Higher risks were observed for specific categories of painters, metal, textile and electrical workers, for miners, transport operators, excavating-machine operators, and also for non-industrial workers such as concierges and janitors. Industries entailing a high risk included salt mining, manufacture of carpets, paints, plastics and industrial chemicals. An increased risk was found for exposure to PAHs (OR for highest exposure tertile = 1.23, 95% CI = 1.07–1.4). The risk attributable to occupation ranged from 4.2 to 7.4%, with an estimated 4.3% for exposure to PAHs. Conclusions: Metal workers, machinists, transport equipment operators and miners are among the major occupations contributing to occupational bladder cancer in men in Western Europe. In this population one in 10 to one in 20 cancers of the bladder can be attributed to occupation.

Komatiites of the Onverwacht Group, S. Africa: REE geochemistry, Sm/Nd age and mantle evolution

Abstract: Komatiites of the Tjakastad Subgroup of the Onverwacht Group (S. Africa) were dated by the Sm/Nd method. A whole-rock isochron yields an age of 3.56±0.24 (2σ) AE, with initial 143Nd/144Nd ratio of 0.50818±23 (2σ), corresponding to ɛNd(T)= + 1.9±4.5. This age is interpreted as the time of initial Onverwacht volcanism. This result agrees with earlier Sm/Nd data of Hamilton et al. (1979) and is consistent with the Rb-Sr result of Jahn and Shih (1974).