With the formation of the world, the radioactivity affected humanity throughout history. The rock beds beneath the soil layer forming natural radioactivity are sources of terrestrial radioactivity. Environmental gamma radiation consists of terrestrial and cosmic sources. The gamma dose rate method is used to determine the radiation emitted by the terrestrial radiation. In this study, the gamma dose rates were determined by conducting measurements at twenty points at intervals of 12 km from Kulakçayırı Lake and its vicinity. Outdoor gamma doses in the air at a height of 1 meter above the ground level were measured using a portable gamma scintillation detector. The measurements were made once per hour. The average outdoor gamma dose values measured at 20 locations measured per hour in the air at an altitude of 1 m was 37.5 nGy / h.

This study was carried out in order to calculate the concentrations of radioactivity in the natural Kulakcayırı Lake of Istanbul (Turkey). Three core samples were taken from Kulakcayırı Lake by drilling and taken from heights of 5-5.5 m, 10-10.5 m and 15-15.5 m at the same point and then moved to the laboratory. According to the laboratory results, the K-40 concentrations of the samples were 325 ± 18 Bq/kg, 353 ± 19 Bq/kg and 367 ± 19 Bq/kg, while their Th-232 concentrations were 38 ± 6 Bq/kg, 43 ± 6 Bq/kg and 42 ± 6 Bq/kg, respectively. Their concentrations of Ra-226 were calculated as 29 ± 5 Bq/kg, 26 ± 5 Bq/kg and 26 ± 5 Bq/kg, while the Cs-137 concentrations of the three samples were calculated as ≤MDA (Minimum Detectable Activity) and existed at very low concentrations. The average activities of K-40, Th-232, Ra-226 and Cs-137 were found to be 348 ± 186 Bq/kg, 41 ± 6.3 Bq/kg, 27 ± 5.1 and ≤MDA, respectively. The results were compared with those of similar studies. These findings and assessments are expected to be an example for future studies and to be of reference quality.

This study investigated the trace element potential of stratigraphic units in Kulakçayırı Lake and its vicinity, in Arnavutköy. In this context, trace element analysis was carried out using three drilling samples taken from Kulakçayırı Lake. In addition, grain size distribution analyses were performed to determine the lithological properties of the drilling samples in the stratigraphic sequence. At the base of the lake bed, there is a distribution of sediment consisting of clay from 3 to 6.5 m thick, and at deeper levels, clayey sand, or sandy clay.In the analyses, nineteen separate elements and CaO, TiO2 and Fe2O3 concentrations were determined using X-ray spectrometry methods. Wavelength Dispersive X-Ray Fluorescence Spectrometry (WDXRF) was used for these measurements.As a result of the elemental analysis, heavy metals including cobalt (Co), nickel (Ni), copper (Cu), lead (Pb), chromium (Cr), and radioactive elements including uranium (U) and thorium (Th), were detected in the sediments. In addition, rare metals (lanthanum, cerium and neodymium) of the lanthanide group were also found. In particular, the elevation of the Pb concentration in the BH-1 drilling location is remarkable. This height is due to the sediment structure around the natural lake.

In this study, the date of the Holocene sediments of Kulakçayırı Lake was determined and the sedimentation rates were calculated. The determined sedimentation rates provide important clues about the climatic and ecological characteristics of the study area. Especially in aquatic environments, it is important to date sediment processes in order to monitor the time-dependent changes in the pollution processes of sediments. In this context, radiocarbon (14C) analysis was performed in order to date the sediments. Liquid scintillation spectrometry was used to find the radioactivity of the 14C isotope. Three drilling samples were taken from the study area (Kulakçayırı Lake / Istanbul) for 14C analysis. According to the results of 14C analysis of the samples taken; Sediment deposition in SK-1 sample took place in 5599 years, in SK-2 in 7596 years and in SK-3 in 8060 years. Sedimentation rates are; SK-1> SK-2> SK-3. From the data obtained, it was observed that the sedimentation rate has different rates at different points of the lake. There is no stream bringing material to the lake. Therefore, it can be said that a slow storage dominates the lake in general.