Risk terminology--a platform for common understanding and better communication.

The sciences analyzing and describing risks are relatively new and developing, and the associated terminologies are developing as well. This has led to ambiguity in the use of terms, both between different risk sciences and between the different parties involved in risk debates. Only recently, major vocabularies have been compiled by authoritative agencies. Some of these vocabularies are examined and explained based on a division into fundamental and action oriented risk terms. Fundamental terms are associated with description and characterization of the chemical, biological and physical processes leading from risk source(s) to possible consequences/effects. The approach to these terms is based on a cause-effect skeleton. The action oriented terms cover administrative, scientific, sociological, etc. processes associated with the work of identifying, characterizing, regulating and communicating risks in the society, and their internal connection and iterative character have been illustrated. Focus is laid on engineering and toxicological risks, but to some extent, the thoughts presented may be extrapolated to other areas. Differences in applied terminology probably cannot be eliminated, but they can be identified and clarified for better understanding. With the present paper, the authors hope to contribute to reducing the probability of derailing risk discussions from the risk issue itself.

Water ethics--a substitute for over-regulation of a scarce resource.

Water scarcity is increasing due to increasing demand and diminishing resources. The water scarcity issues have to be distinguished according to availability and applicability, because urban water use does not consume water, but pollutes it. Water scarcity may be regulated by "command and control" and more recently by "economical instruments". Water ethics is an important, but frequently ignored element in regulation. Equity in availability and applicability of water is the important ethical issue at all levels, from local community to the global scale. The distribution of rights and duties is problematic and no easy solutions are in sight, but attention and awareness are essential. The ethical community has been expanded from a human dimension to include an ecological dimension, which aggravates the dilemma. There have been too many surprises in water quality development, due to unforeseen negative effects of activities in the modern society. Decision making relative to complex systems is frequently marred by uncertainty and ignorance. In such cases, solutions have to be robust, flexible and adaptable to unforeseen changes.

Population changes in a biofilm reactor for phosphorus removal as evidenced by the use of FISH.

Induction of denitrification was investigated for a lab-scale phosphate removing biofilm reactor where oxygen was replaced with nitrate as the electron acceptor. Acetate was used as the carbon source. The original biofilm (acclimatised with oxygen) was taken from a well-established large-scale reactor. During the first run, a decrease in the denitrifying bio-P activity was observed after 1 month following a change in the anaerobic phase length. This was initially interpreted as a shift in the microbial population caused by the changed operation. In the second run, biomass samples were regularly collected and analysed by fluorescent in situ hybridisation (FISH) and confocal laser scanning microscopy (CLSM). Concurrently, samples were taken from the original reactor with oxygen as electron acceptor in order to investigate natural microbial fluctuations. A similar decrease in the activity as in the first run was seen after one month, although the phase lengths had not been varied. Hence, the decrease after 1 month in the first and second run should be seen as a start-up phenomenon. FISH could detect a noticeable shift in the microbial population mainly within the first 2 weeks of operation. Almost all bacteria belonging to the alpha subclass disappeared and characteristic clusters of the beta and gamma subclasses were lost. Small clusters of gram-positive bacteria with a high DNA G + C content (GPBHGC) were gradually replaced by filamentous GPBHGC. Most of the bacteria in the denitrifying, phosphate removing biofilm belonged to the beta subclass of Proteobacteria. The applied set of gene probes had been selected based on existing literature on biological phosphate removing organisms and included a recently published probe for a Rhodocyclus-like clone. However, none of the specific probes hybridised to the dominant bacterial groups in the reactors investigated. No noticeable changes were detected in the aerobic bench-scale reactor during this period, indicating that the observed changes in the lab-scale reactor were caused by the changed environment.