Reduced sulfur species in a marine euxinic environment of Rogoznica Lake – Dragon Eye, Croatia

Mateša, Sarah; Dominović, Iva; Marguš, Marija; Ciglenečki-Jušić, Irena (2025) Reduced sulfur species in a marine euxinic environment of Rogoznica Lake – Dragon Eye, Croatia. Acta Adriatica, 66 (1). ISSN 0001-5113

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Abstract

Rogoznica Lake (RL) – Dragon Eye is a unique, eutrophic marine lake on the eastern Adriatic coast. The lake exhibits seasonal variations between stratified and anoxic holomictic conditions. Under stratified conditions, RL shows typical euxinic features characterized by an euxinic hypolimnion (< 8 meters deep in recent years) with a relatively high total concentration of reduced sulfur species (RSStot). These species are mainly present in the form of sulfides, non-volatile RSS (RSSnv) attributed to elemental sulfur (S0), and polysulfides (Sx2-). The concentration of RSStot, particularly the RSSnv and Sx2-, varies seasonally depending on the physicochemical conditions in the water column, i.e. the position and stability of the chemocline and the entire water column, expressed by the Schmidt Stability Index (SSI), as well as the light intensity reaching this layer. In the summer months, when stratification is the strongest, the concentrations of the RSSnv in and below the chemocline are generally higher. In addition, the highest concentrations of Sx2- (up to 90 µM of polysulfidic S0) are detected during this period. This increase is related to a more intense microbial activity of phototrophic purple sulfur bacteria (PSB), which then reach maximum abundance due to the increased temperature and maximum light intensity. Typically, the highest concentrations of Sx2- are found below the chemocline. Long-term data indicate that the concentration of RSSnv at the chemocline and 1 m below it depends on the hydrostatic stability of the water column and shows periodic changes. This contrasts with the previously recorded trend of increasing RSStot in the anoxic monimolimnion.

Item Type:	Article
Uncontrolled Keywords:	reduced sulfur species; elemental sulfur; polysulfides; long-term data; Rogoznica lake
Subjects:	NATURAL SCIENCES > Interdisciplinary Natural Sciences > Marine Science
Divisions:	Division for Marine and Enviromental Research
Projects:	Project title Project leader Project code Project type Rogozničko morsko jezero kao model odziva ekosustava na promjene u okolišu-MARRES Irena Ciglenečki-Jušić IP-2018-01-1717 HRZZ Izotopni otisak stratificiranog morskog jezera (Zmajevo oko) Irena Ciglenečki-Jušić IP-2024-05-2377 HRZZ
Depositing User:	Lorena Palameta
Date Deposited:	15 May 2025 12:35
URI:	http://fulir.irb.hr/id/eprint/9824
DOI:	10.32582/aa.66.1.1

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