Page 22 - Studia Universitatis Hereditati, vol 13(2) (2025)

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studia universitatis hereditati, letnik 13 (2025), številka 2 / volume 13 (2025), number 2

Figure 7: Coring in Jaz Bay With an Eijkelkamp Percussion Drilling Set – Hammer Cobra TT, Cores JAZ 1 and 2
(elaborated by Nives Doneus, 2024)

(UWITEC, Austria) placed on the coring plat- organic matter was removed from 0.1–0.2 g of
form with a tripod. Cores were cut in the labora- the sample with hydrogen peroxide (H2O2) (Al-
tory of the Croatian Geological Survey into 1.4 len and Thornley 2004). Since most of the sam-
m-long segments and split longitudinally. One ples in this karst environment are predominant-
half of each core was archived, while the other ly composed of carbonate material, they were not
half’s surface was smoothed and photographed. pretreated with hydrochloric acid (HCl). Fos-
Two cores were also taken from the Jaz Bay sil shells were manually removed from the sam-
tidal inlet, (JAZ 1 and 2, fig. 1 and fig. 7) with ples. Sodium hexametaphosphate ((NaPO3)6)
an Eijkelkamp percussion drilling set – hammer was added to allow dispersion and prevent par-
Cobra TT. The water depth during coring varied ticle aggregation. We used the GRADISTAT 8
from 0 to 20 cm depending on the tidal oscilla- software (Blott and Pye 2001) for statistical data
tions. The core JAZ 2 was dated using the opti- processing. For the sediment classification, the
cally stimulated luminescence profiling and dat- Folk and Ward (1957) method was applied.
ing (OSL-PD) method.
The cores were subsampled for particle size Organic Carbon and Nitrogen
analysis (PSA); total carbon (TC), total organ- To measure organic carbon (TOC), total ni-
ic carbon (TOC), total inorganic carbon (TIC) trogen (TN), total inorganic/carbonate carbon
and total nitrogen (TN) concentration measure- (TIC), and insoluble residuum (IR), a Thermo
ments. The results for cores OSOR 2 and JAZ 2 Fisher Scientific (Waltham, MA, USA) Flash
are discussed in this paper. 2000 NC Analyzer was used. Two grams of bulk
sediment were freeze-dried and ground. The sam-
Grain-size Distribution ples were packed into tin capsules for the anal-
A Shimadzu (Kyoto, Japan) SALD-2300 laser ysis of total carbon (TC) and TN. To measure
diffraction particle size analyser was used to an- TOC, the carbonate component was removed
alyse the particle size distribution in sediment by HCl. The TIC was calculated as the differ-
core samples. The instrument measures particle ence between TC and TOC. The C/N ratio was
diameters between 0.017 and 2500 μm. First, the calculated by dividing the TOC and TN. Insol-