Non-equilibrium thermodynamics of ecosystems: Entropic analysis of stability and diversity

The aim of the paper is first to develop a non-equilibrium thermodynamic model of a multi-species ecosystem. The key to this is the expression of entropy-production (change of entropy) which is equivalent to a well-known expression of Liapunov function used in many problems of ecological and chemical reaction systems. On the basis of the expression of entropy-production we have made an entropic (thermodynamic) analysis of ecological stability (both global and local) including the study of interrelation between ecological diversity and stability. As illustrative examples we have discussed some basic problems of classical and generalized Lotka–Volterra systems.     

Application of capillary electrophoresis combined with a modified BCR sequential extraction for estimating of distribution of selected trace metals in PM2.5 fractions of urban airborne particulate matter

The capillary electrophoresis (CE) method combined with a sequential extraction was applied to determine the distribution of Fe, Zn, Cu, Mn and Cd in urban ambient air PM2.5 samples. PM2.5 was collected on Teflon filters with dichotomous sampler, and the modified extraction procedure following the BCR leaching procedure was used to chemically fractionate metals into "easily exchangeable" with water, "acid extractable" with 0.11 mol/l acetic acid, "reducible" with 0.1 mol/l hydroxylamine hydrochloride acidified to pH 2.0 with nitric acid, and "oxidisable" with oxidation by 8.8 mol/l hydrogen peroxide (H2O2) followed by extraction with 1.0 mol/l ammonium acetate. Based on the obtained results it was concluded that the application of the studied methodology provides chemical fractionation data that reflect the general sources and potential health hazards of the studied metals.