Gulf of Riga, Latvia's coastal zone of the Baltic Proper

Concentration of polychlorobiphenyls (PCBs) in biota; Metal concentrations in biota

Benthos samplers; atomic absorption spectrometers; gas chromatograph mass spectrometers

The monitoring of heavy metals and supporting parameters in mussels (Macoma Balthica), perches (Perca fluviatilis), herrings (Clupea harengus), and viviparous blennies (Zoarces vivipararus) of the Gulf of Riga and the Baltic Sea has been carried out from 1996 to 2002 and 2006. PCB pilot studies in mussels (Macoma Balthica), perches (Perca fluviatilis), and herrings (Clupea harengus) were conducted in 2002. Cadmium, copper, lead, zinc levels were measured in soft tissues of mussels and fish livers. Mercury and PCB were measured in soft tissues of mussels and fish muscles. Water content was determined in all tissues for data transferring to dry weight except PCB data. The measurements were performed within marine monitoring program. Mussel sampling was done using Van Veen grab on deck of research vessel 'Antonija' once a year since 2000. Sampling stations were located against three large river mouths in the Gulf of Riga. In 2000 and 2001 samples were taken from 10 m depth but since 2002 sampling sites have been moved to 20 m isobaths. Mussels were separated in three groups by size: 10-15 mm, 16-18 mm, and >19 mm. Fishing nets were used for perches and viviparous blennies collection from certain sampling areas as to represent all coastal habits. Herrings were collected by trawl in the central part of the Gulf of Riga in 2002. Two years old females were collected for analysis. In one sample were incorporated tissues of five fishes. Digestion for metal analysis 1996-1999 wet digestion with nitric acid and hydrogen peroxide. Since 2000 wet digestion with nitric acid in microwave oven closed system. For Hg wet digestion with sulphuric acid, potassium permanganate and potassium persulphate since 2000. For PCP extraction with mixture of n-hexane, acetone and diethyl ether or extraction with cyclohexane since 2002. Digested samples were analysed by atomic absorption spectrophotometer. Cu and Zn by flame, Cd and Pb - graphite furnace, Hg - cold vapour technique. PCB were analysed by GC/MS.

Latvian Institute of Aquatic Ecology
Voleru str.4
Riga

LV-1007
Latvia