Over time, there has been a steady increase in the area affected by hydrogen sulphide in the East and West Gotland Basins, and the outer Gulf of Finland.
Thar am, tá méadú comhsheasmhach tagtha ar an limistéir ina bhfuil tionchar ag an suilfíd hidrigine in Imchuacha Gotland Thoir agus Thiar, agus i Murascaill na Fionlainne.