Metals in sediments of inland waters of Latvia

Multielement analysis (by means of instrumental neutron activation analysis - INAA) of sediments in streams and lakes in Latvia was conducted. Total element concentrations, their variability and their speciation forms in sediments (exchangeable, carbonate bound, iron-manganese oxide bound, organic matter bound and residual) were compared. Increased metal concentrations were found in the lower reaches of the largest rivers and locally around known industrial pollution sources. Metal concentrations in stations from different regions of Latvia were related to natural geochemical processes and contamination levels. Metal speciation analysis showed that the dominant metal species were residual metals and those bound to organic matter. Residual and carbonate-bound forms dominated only in rhitral regions of rivers. The concentrations of exchangeable metals increased below pollution sources. Metal concentrations were compared with their geochemical mean values.