ESTIMATED BACKGROUND CONCENTRATIONS OF SULFATE IN DILUTE LAKES1

ABSTRACT: Lake water sulfate values were examined for two areas in western Norway and the western United States presently receiving low levels of sulfate in atmospheric deposition. Data from these areas were used to estimate background concentrations of sulfate in lakes found in areas currently receiving acidic deposition. The two areas contain dilute lakes with concentrations of sea-salt corrected Ca+ Mg less than 50 μeq/l or conductivity < 10μS cm^-1and receive precipitation with volume-weighted mean pH > 4.8. Based on observations from these areas, we conclude that background sulfate concentrations were probably no more than 10 to 15 μeq L^-1for areas of Norway and the U.S. containing lakes with low concentrations of base cations. For southern Norway and the northeastern U.S., present lakewater sulfate concentrations represent an increase of 7 to 10 fold above these estimated background values.     

More is not always better: coping with ambiguity in natural resources management

Coping with ambiguities in natural resources management has become unavoidable. Ambiguity is a distinct type of uncertainty that results from the simultaneous presence of multiple valid, and sometimes conflicting, ways of framing a problem. As such, it reflects discrepancies in meanings and interpretations. Under the presence of ambiguity it is not clear what problem is to be solved, who should be involved in the decision processes or what is an appropriate course of action. Despite the extensive literature about methodologies and tools to deal with uncertainty, not much has been said about how to handle ambiguities. In this paper, we discuss the notions of framing and ambiguity, and we identify five broad strategies to handle it: rational problem solving, persuasion, dialogical learning, negotiation and opposition. We compare these approaches in terms of their assumptions, mechanisms and outcomes and illustrate each approach with a number of concrete methods.