Increasing levels of hydrogen sulfide in the Black Sea

The Black Sea is facing increasing levels of hydrogen sulfide (H₂S), a highly toxic gas that poses significant environmental risks. Due to unique conditions, the Black Sea contains one of the world’s largest naturally occurring H₂S reserves, primarily in its deeper waters where oxygen levels are too low to support most marine life. This phenomenon is driven by bacterial activity that produces H₂S as organic matter decomposes in anoxic conditions. Over recent decades, warming and deoxygenation have caused the habitable layer of the Black Sea to compress, bringing H₂S closer to the surface and potentially increasing its impacts on marine ecosystems​.

Rising temperatures and sea-level changes also threaten to release more H₂S from deep-sea gas hydrates. This could destabilize marine life and exacerbate ecological risks, as elevated H₂S levels can disrupt food chains and harm coastal communities that rely on fishing​. Furthermore, scientists warn that if H₂S levels were to increase closer to the oxygenated layers, it could have severe repercussions for biodiversity and human health in the region​.

Addressing these risks requires close monitoring and strategic environmental management to mitigate the impacts of H₂S on the Black Sea’s delicate ecosystem.

• https://www.sciencedaily.com/releases/2016/09/160901093155.htm
• https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2022.1018325/full
• https://link.springer.com/chapter/10.1007/978-94-007-6152-0_2