Input of hydrocarbons into the North Sea by the river Elbe

An analytical procedure for evaluating the conditional stability constants K of aluminum/humic substance complexes, based on ²⁷Al nuclear magnetic resonance spectroscopy, is described. It is well suited for the determination of Al(III) dissociated from dissolved humic substances at slightly acidic pH values. The new procedure offers a good sensitivity and requires neither special preparation of the sample nor the evaluation of complex coupled chemical equilibria. The pK values range from 2.0 to 4.3 depending on the ratio [Al_complex] to dissolved organic carbon and the pH.Dedicated to Professor Dr. Dieter Klockow on the occasion of his 60th birthday