Naslov
The role of biologically produced elementary sulfur (S0) on polysulphide formation in the marine euxinic environment (Rogoznica Lake)

Autori
Mateša, Sarah ; Čanković, Milan ; Šegota, Suzana ; Ciglenečki, Irena

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Simpozij studenata doktorskih studija PMF-a : knjiga sažetaka = PhD student symposium 2021 : book of abstracts / Barišić, Dajana - Zagreb : Prirodoslovno-matematički fakultet Sveučilišta u Zagrebu, 2021, 121-122

ISBN
978-953-6076-90-1

Skup
5. Simpozij studenata doktorskih studija PMF-a = 5th Faculty of Science PhD Student Symposium

Mjesto i datum
Zagreb, Hrvatska, 24.04.2021. - 25.04.2021

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Podatak o recenziji nije dostupan

Ključne riječi
Rogoznica Lake ; purple phototrophic sulfur bacteria (PSB) ; polysulfides ; biologicaly produced sulfur

Sažetak
Rogoznica Lake (RL) is a naturally eutrophicated marine lake on the eastern coast of the Adriatic (43°32’ N, 15° 58’ E) with meromictic and euxinic properties. The main characteristic of the lake is the seasonal thermohaline and chemical stratification of water layers into the upper oxic and lower anoxic layers. Due to intense sulfate reduction, the anoxic layer is rich in dissolved HS- (up to 5 mM). At the oxia-anoxia boundary, a pinkish colored chemocline (up to 50 cm) develops seasonally, and it is characterized by a dense population of purple phototrophic sulfur bacteria (PSB) [1]. PSB are known to store sulfur S(0) intracellularly, which by cell lysis would be released in water, and under euxinic conditions solubilized by HS- in nucleophilic polysulfides, SX2-. In this work, for the first time in natural samples, differential pulse voltammetry (DPV) was used for direct determination of SX2- in the euxinic aqueous environment (RL), where concentrations of total reduced sulfur species (RSS) varies between 0.1 and 3 mM (mainly HS-). RSS, as well as SX2- concentrations varied seasonally depending on the chemocline position, light intensity, and HS- concentration. In the summer, when PSB reached maximum abundance, the highest concentrations of SX2- (up to 0.1 mM polysulfide S (0)) were determined at a depth of about 1 m below the chemocline. Due to sinking of lysed PSB cells, maximum concentration of biologcally produced S(0) would be expected at that depth. Vertical mixing usually occurs during autumn or winter when cold, oxygen-rich water from the surface sinks downwards. In such conditions, a dense purple layer of PSB disappears, and SX2- are not detected. The seasonal dependence of the concentration distribution of SX2- on physicochemical factors indicates the importance of biologically produced S (0) for the formation and presence of SX2-. Also, in samples rich in PSB, by acidification procedure used as a standard methodological step [2] in the electroanalytical determination of nonvolatile RSS (RSSNV), an increase in RSSNV concentration of 30-50% was observed. AFM analysis of RL sample with PSB confirmed the presence of intracellular granules of S (0) which are released after cell lysis in induced laboratory conditions by acidification. Released biological S(0) contribute to the RSSNV and the formation of SX2-in the euxinic layer of RL.

Izvorni jezik
Engleski

Znanstvena područja
Kemija, Biologija, Interdisciplinarne prirodne znanosti

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