Suchergebnisse

AbstractBenthic cyanobacterial mats occurring in the St. Lawrence River fluvial lakes Saint-Louis and Saint-Pierre are dominated by Microseira (Lyngbya) wollei which produce several cyanotoxins including LWTX-1 that is characteristic of Microseira wollei. This cyanotoxin is not only present in the filaments forming benthic mats, but was also measured in the water overlying the mats. LWTX-1 was found in all cyanobacterial filament samples (75.29–103.26 ng mg−1) and all overlying water samples (3.01–11.03 ng L−1). Toxin concentrations measured in overlying water and dry biomass were strongly correlated (r = 0.94). Furthermore, LWTX-1 concentration in water was positively correlated with the dissolved organic carbon in water (r = 0.74) and % nitrogen content in cyanobacterial filaments (r = 0.52). A preliminary study was conducted to determine the release and degradation rates of LWTX-1 from a M. wollei mat kept under laboratory conditions over a 3-month period. Toxin measurements revealed an early, massive toxin release followed by a typical decaying function, with a half-life in the order of 17 days. Our results raise concerns about the occurrence and downstream advection of dissolved cyanotoxins from Microseira mats in the aquatic environment.

For many white South Africans, black demands for redistribution conjure up images of a new South Africa with no future; a country in which the state arbitrarily redistributes proceeds, assets and jobs. At the other extreme are many black South Africans who imagine redistribution to be the key to Utopia, to relief from misery and deprivation. Although there is no quick-fix solution, the status of the political and economic debate on redistribution as reflected in this book, reveals a convergence of views on a number of crucial issues in both the public and private sector, including employment, black empowerment, equal opportunity enhancement, structural constraints on change, contending policy positions and relevant African experience. The widely shared proposal of a mixed economy in a new South Africa is a prime example. (DÜI-Hff)