Selenite and selenate effects on mercury (Hg(2+)) uptake and distribution in tilapia, Oreochromis niloticus L., assessed by chronic bioassay.

Aquatic organisms are considered excellent biomarkers of mercury (Hg) occurrence in the environment. Selenium (Se) acts in antagonism to this metal, stimulating its elimination, and reducing its toxicity. In this paper, tilapia (Oreochromis niloticus) were chronically acclimated in sub-lethal Hg(2+), Hg(2+) + Se(4+) and Hg(2+) + Se(6+) concentrations. Distribution and bioaccumulation of both elements were evaluated in fish tissues. The kidney was the main target of the Hg and Se uptake, and the presence of Hg induced the Se hepatic elimination. The Hg bioaccumulation in the gill, spleen and heart were higher in the presence of Se(6+) than in the presence of Se(4+).

Correlaçäo entre contagens de células somáticas determinadas no "Somacount 300" utilizando-se os detergentes RBS 35 e Extram MA 01 alcalino / Correlation between milk somatic cell counting of samples prepared with two detergents, and analyzed by the Somacount

The objective of this work was to compare the values of milk somatic cell counts (SCC) using the Somacount 300, and two detergents for sample preparation. the equipment was calibrated using the detergent RBS 35. Forty independent milk samples were analyzed. Each sample was randomly divided into two subsamples, and each subsample was analyzed after preparation with either RBS 35 or Extram MA 01 Alkaline detergents. the correlation coefficient between the two methods was high (0.998). This finding suggests the possibility of substitution of RBS 35 for an economical alternative

Environmental control in the uranium mine Lagoa Real, Brazil.

Uranium production in Brazil will be restarted in the year 2000, through exploration of the Jazida da Cachoeira, located in the uraniferous region of Lagoa Real, Bahia State, northeast Brazil. Because of the mining operations, an open cast mine of approximately 27 x 10(4) m2 will be produced and the material removed will constitute approximately 14 x 10(6) tons, occupying an estimated area of 50 x 10(4) m2. Currently, there is a new concept about project developing, where the impact assessment is addressed during the initial phases. Beside this, legislation requires an environmental impact assessment before starting mining activities. In this context purpose, it is the purpose of this work to evaluate the chemical composition of the future waste; thus, samples were collected from the rocks that surround the mineral deposits. Instrumental neutron activation analysis was used for the elemental quantification, the mean elemental concentrations were calculated, and the ratios were normalized using North American Shale Composite (NASC). In the raw material eight main mineral structures exist whose elementary composition were compared using the statistical techniques of analysis of variance, ranking ANOVA, and multivariate ANOVA.