Effect of pH and temperature on the sorption of Np and Pa to mixed anaerobic bacteria.

While considering the geological disposal of radioactive wastes, the behaviour of the radionuclide Np and its daughter element Pa was investigated in the presence of a mixture of anaerobic bacteria (MAB). Originally, MAB were used for the treatment of pulp and paper wastewater. The interaction between radionuclides and bacteria was evaluated by determining distribution coefficients (Kd) over 10 days and at 5 degrees C and 35 degrees C. Kd for Np at 35 degrees C after 5 days had a low value around 10(-2) After 10 days, however, Kd was > 100-fold higher. On the other hand, Kd at 5 degrees C was low (10(-2)) throughout, without any significant increase over time. The interaction between Pa and MAB was found to be stronger than that for Np, with Kd for Pa about 100 times higher. The Kd was controlled by some basic factors, the activity of MAB, the complexing capacity of MAB, and the chemical conditions in the solution such as pH and Eh.

Environmental health and monitoring in Estonia.

An assessment of environmental health and monitoring in Estonia after the dissolution of the Soviet Union has shown that the country suffered from neglect during the "cold war" after World War II, and efforts to improve the status quo have been slow since independence was gained in 1991. Conditions in Estonia are affected by the fifty-year long occupation. Industrial, military and agricultural activities have left a legacy of pollution and obsolete installations. The regulatory framework and life style attitudes from the Soviet era interfere with reform efforts. The current transition period holds risks that derive from a run-down infrastructure, a weak economy, and disruptions, inherent in the reorganization itself. Over the past few years a recession has further complicated the situation and the public health status has worsened. International assistance programmes as well as efforts by Estonians have led to some change and progress in environmental management since 1991, and lately ambitious environmental and public health sector programmes have been initiated by the government. Much work, however, still needs to be done. An examination of the recent history of this small country provides examples of environmental neglect and consequences, as well as recommended corrective measures.

Molecular techniques and their potential application in monitoring the microbiological quality of indoor air.

Health effects associated with poor indoor air quality have created a need for accurate, reproducible methods of monitoring the microbiological content of indoor air. Improved methods of detection may allow researchers to clarify the effect of individual species present in the indoor environment on human health. This review discusses the shortcomings of current methods of identification and detection and focuses on the potential for molecular techniques in this emerging field. Probe techniques, restriction endonuclease analysis, karyotyping, and DNA and polymerase chain reaction fingerprinting methods available to detect and identify bacteria and fungi significant in the indoor air environment are discussed. Problems that may be encountered using these techniques are also considered. The authors have included a brief discussion on current air sampling techniques as well as adapting these techniques for use with molecular detection methods.

A practical isolation of methyl mercury in natural waters.

A simple method to isolate both organic and inorganic mercury in natural waters is described. The mercuric compounds were quantitatively extracted with dithizone from six different kinds of water spiked at nanogram levels with radioactive mercuric chloride and methylmercuric chloride. After the separation from the inorganic mercury with sodium nitrite, methyl mercury was transferred to aqueous medium with sodium thiosulfate. The method provides a high recovery of organic as well as inorganic mercury to an aqueous medium, prior to their determination by gold-trap cold vapor atomic absorption spectrophotometry. This method is easy, rapid, and inexpensive. Furthermore, the limited number of analytical steps should reduce loss and contamination.