Figure 6.5 Log-log plot of the ratio of nitrogen to phosphorus turnover rates, R, at maximum exergy versus the logarithm of the nitrogen/phosphorus ratio, log N/P. The plot is consistent with Vollenweider (1975).
resource is non-limiting. A modeling study (Jorgensen, 2002) indicated that free-energy storage increases when an abundant resource recycles faster. Figure 6.5 shows such results for a lake eutrophication model. The ratio, R, of nitrogen (N) to phosphorus (P) cycling which gives the highest exergy is plotted in a logarithmic scale versus log (N/P). The plot in Figure 6.5 is also consistent with empirical results (Vollenweider, 1975). Of course, one cannot "inductively test" anything with a model, but the indications and correspondence with data do tend to support in a general way the exergy storage hypothesis. The cycling ratio giving the highest ascendency is also correlated similarly to the N/P ratio (Ulanowicz, personal communication). In the light of the close relationship between exergy and ascendency this result is not surprising (see above, Jorgensen, 1995; Ulanowicz et al., 2006).
Was this article helpful?
Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.