Copper complexation in eutrophic and humic Lake Tjeukemeer, The Netherlands

Abstract

SUMMARY. 1. Copper(II) complexation in the eutrophic. humus‐rich Lake Tjeukemeer was measured fortnightly for several years by copper titration (Ion Selective Electrode) and by copper solubilization. Additionally, the copper speciation during titration was followed by ultrafiltration. 2. The Tjeukemeer showed high ligand concentrations able to complex up to 8.5X10 ‐5 M Cu. 3. Scatchard plots and affinity spectra of the titration data allowed the discrimination of at least three different binding sites. In Scatchard plots log K values ranged from 5 to 9, in affinity spectra from 4.5 to 8. 4. The highest log K values coincided with relatively low humus concentrations and blooms of algae, mainly Cyanobacteria. 5. The ultrafiltration experiments indicated that relatively small size fractions (<10 nm) have the highest copper binding affinity.