Naslov
SULPHUR ISOTOPES IN SOIL AROUND THE THERMOELECTRIC POWER PLANT PLOMIN (CROATIA)

Autori
Malenšek, Neža ; Medunić, Gordana ; Lojen, Sonja ; Zupančič, Nina

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

Izvornik
Book of Abstract: ESIR Isotope Workshop XIV / Ionete, Roxana E. - Băile Govora : National Research and Development Institute for Cryogenics and Isotopic Technologies - ICSI Rm. Vâlcea, 2017, 133-134

ISBN
978-973-0-24503-5

Skup
ESIR Isotope Workshop XIV European Society for Isotope Research – ESIR 2017

Mjesto i datum
Băile Govora, Rumunjska, 25.06.2017. - 29.06.2017

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
sulphur isotopes, SHOS Raša coal, soil, thermoelectric power plant

Sažetak
This study reports for the first time the sulphur isotopes and S forms measured in soil polluted with sulphur derived from the thermoelectric power plant Plomin (TPPP). The TPPP is located on the eastern coast of the Istrian peninsula (North Adriatic, Croatia), and is considered as the prime air polluter in Istria (Božičević Vrhovčak et al., 2005). During the period 1970-2000, the TPPP was powered by the domestic Raša coal. It is characterised by high natural radioactivity, and uniquely high sulphur content up to 14 wt. % (Medunić et al., 2016a), and is known as super high-organic-sulphur (SHOS) coal (Chou, 2012). Since 2000, imported low-S coal has been in use, but the presumable airborne ash particles from a nearby waste could be considered as a source of the environmental pollution. Chemical analysis of soil in the vicinity of the TPPP showed that the soil is severely polluted with sulphur and polycyclic aromatic hydrocarbons, while moderately with Se, and Cd (Medunić et al., 2016b). Sulphate aerosols were considered as a major pollution source, however, little has been known about the fate of sulphur in soil following the switch in fuel to low-S coal. In this study, newly collected soil samples (n=11), 3 samples of ash, and 6 SHOS Raša coal samples were analysed for the sulphur content and its stable isotopic composition (δ 34S). The aim of the study was to estimate the source and fate of S in the investigated topsoil. The soil samples were taken at different distances downwind (SW) from the TPPP, while the control soil was sampledupwind (NE) 10 km away from the TPPP. Analytical work included the following measurements: total S in coal, sulphate in ash, and sulphate and the organic (humic and fulvic) sulphur in soil. The extraction of total sulphur from coal, ash, and humic extracts was made by the combustion with Eschka mixture. Following the wet chemical process, sulphate was recovered in the form of BaSO4 (Brüchert and Pratt, 1996). Sulphur concentrations in bulk samples, together with the isotopic composition of S were determined by EA-IRMS (IsoPrime 100 with PyroCube). The bulk S concentration in the SW soil sample at 100 m distance from the TPPP (close to 4 wt. %) is significantly higher compared to that at the control site(0.04 wt. %), and decreases rapidly to less than 0.6 wt.% in a distance of 0.5 km (Figure 1A). The speciation analysis showed that the majority of S (>95 %) is present in organic form, mostly bound to humic acids (Figure 1B). The δ 34S values of bulk Raša coal samples were between -5 and -10 ‰. In most soil samples within 1 km from the TPPP, bulk δ 34S were slightly positive. The δ34S values of sulphate in soil samples were between +1 and +5.5 ‰. The δ 34S values of humic acids ranged from -3.5 to 3 ‰, while fulvic S showed positive values for all soil samples, namely between 1.5 and 6 ‰. These results are indicative of the atmospheric deposition of 34S- depleted fly ash and sulphate, which had derived from the SHOS Raša coal combustion as the main sources of S in analysed soils close to the TPPP. At distances exceeding 1 km, δ 34S values of soil S gradually increase to values more than 20 ‰, which indicates on a fading influence of airborne contamination from the TPPP.

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Geologija, Kemija

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