Inorganic and methyl-mercury speciation in sediments of the Swarzędzkie Lake

Abstract

Sediment samples were analysed for mercury and methylmercury content in different parts of the bottom sediment of Swarz ędzkie Lake, which were influenced by different external pollution sources. The results of determination with two methods of mineralization using two separate media (HNO₃/H₂O₂ and HF) were compared. The accuracy of the studied methods was analysed using certified reference material IAEA 405 of river sediment. The recovery of mercury was satisfactory and ranged from 97.5 to 98.8%. Methylmercury compounds in the studied sediments were found in limited concentrations. Their concentrations ranged from 0.26 to 58.1 μg kg⁻¹, i.e. 1.0–7.4% of the total mercury content. The depth profile displayed high values of both total and methylmercury content at a depth of 10–20 cm, related to the heavy pollution of the lake in the 1980s. Canonical analysis displayed the relationship of both total mercury and methylmercury concentrations with organic matter and phosphorus content in bottom sediments.

Keywords:

• Inorganic mercury
• Methylmercury
• Speciation
• Lake sediment
• Organic matter

Acknowledgements

The authors wish to thank Dr Tadeusz Glenc from the TESTCHEM company for access to Automatic Mercury Analyser RA-3000, an indispensable tool for the study. This work was financially supported by the grant KBN 1TO9D 057 30.