Baltic Proper, Gdansk Basin, Bornholm Basin, Arkona Sea, Gotland Basin, Landsort Deep, Faro Deep during the period 1972-1992 (data set limits: 54 53 - 59 23N; 13 23 - 22 11E); Baltic Proper, Gdansk Basin and Gotland Basin during the period 1993-1999 (data set limits: 54 53 - 57 22N; 18 24 - 20 20E); Baltic Proper since 2000 (data set limits: 55 31 - 56 05N; 19 14 - 20 39E)

Alkalinity, acidity and pH of the water column

CTD

The aim of the research is to evaluate active water reaction pH (acid or alkaline) of different regions of the open Baltic Sea. Biological and biochemical processes occuring in water body, development of water plants, migration forms of chemical elements depends on water pH. In accordance with the national and international Baltic Sea monitoring (HELCOM) programme monitoring cruises have been fulfilled with Lithuanian research vessels 'Okeanografas', 'Vetra', 'Vejas'. Since 1972 investigations have been carried out in a wide net of stations in national and international waters (including Baltic Proper, Gdansk Basin, Bornholm Basin, Arkona Sea, Gotland Basin, Landsort Deep and Faro Deep), later the net of stations became more narrow and since 2000 research in the Baltic Sea has been defined more exactly and has been carried out only in the exclusive economic zone of Lithuania. pH investigations are carried out during every season at a constant network of stations in standard sea water horizons. In 1972-1992 research was performed at 35 stations, 1993-1999 - 14 stations and in 2000-2003 - 5 stations. The data are fully quality controlled. Systematic certification of laboratories, participation in an international intercalibrations, internal control, introduced managing system for researches' quality, use of high quality reagents determine quality of data. All data is stored in archive (in table forms on paper) and is saved on hard disk.

Department of Marine Research of the Environmental Protection Agency
Taikos Av. 26
Klaipeda

LT-91149
Lithuania