Radiometric dating 210pb Needham ma naked
The building of the Iron Gate dams (19) had a negative impact on the sedimentation decreasing it with 58.74%, while after 1989 these values grew 2.25 times.
The lake received a quantity of sediment rich in heavy metals in 1992 ± 3 y, which settled mostly on the eastern part.
The aim of this study is to analyse the recent sedimentation rates using the (210)Pb dating method and identifying the heavy metal pollutants and their variability in time.
Five sediment cores were taken with a gravity corer and - after drying the sliced samples-physical parameters, organic material and inorganic carbon content were determined.
Taking into consideration the cardinal regions, the northern and western regions received the least amount of 137Cs (2.9 ± 0.1 k Bq m− 2), while the southern part received 16.3 ± 0.6 k Bq m− 2.
Sampling points with eastern slope exposure received the highest average (27.8 ± 0.5 k Bq m− 2), while southern, north-western and north-eastern ones received less than 8 k Bq m− 2.
After applying the CRS model, ages and sedimentation rates were calculated.
The sedimentation pattern proves this lake to be very sensitive to fluvial discharge fluctuations.
The results were compared to measured data from the Danube Delta and Moldova Republic, as well as to 137Cs concentrations from the rest of Europe reported by literature.
The 137Cs surface concentrations in soil samples ranged between 0.4 ± 0.1 k Bq m− 2 and 301.1 ± 3.0 k Bq m− 2, having an average of 8.3 ± 0.2 k Bq m− 2, with more elevated values in the mountain areas (18.3 ± 0.6 k Bq m− 2) compared to the hills and plains (2.6 ± 0.1 k Bq m− 2).
This is the first study reporting recent sedimentation rates data (e.g.
the past 120-150 years) for the Cruhlig Lake situated in the Danube Delta.
In case of 137Cs the mean was 298±3 Bq m−2 yr−1, maximum being 1683±15 Bq m−2 yr−1 in case of Ighiel area and minimum being 32±1 Bq m−2 yr−1 in the Danube Delta region.