Euxinia

Euxinia or euxinic conditions occur when water is both anoxic and sulfidic. This means that there is no oxygen (O₂) and a raised level of free hydrogen sulfide (H₂S). Euxinic bodies of water are frequently strongly stratified; have an oxic, highly productive, thin surface layer; and have anoxic, sulfidic bottom water. The word "euxinia" is derived from the Greek name for the Black Sea (Εὔξεινος Πόντος (Euxeinos Pontos)) which translates to "hospitable sea".^[1] Euxinic deep water is a key component of the Canfield ocean, a model of oceans during part of the Proterozoic eon (a part specifically known as the Boring Billion) proposed by Donald Canfield, an American geologist, in 1998.^[2] There is still debate within the scientific community on both the duration and frequency of euxinic conditions in the ancient oceans.^[3] Euxinia is relatively rare in modern bodies of water, but does still happen in places like the Black Sea and certain fjords.