Sediment dynamics and heavy metal pollution history of the Cruhlig Lake (Danube Delta, Romania)


Begy R.Cs., Preoteasa L., Timar-Gabor A., Mihaaiescu R., Tanaselia C., Kelemen Sz., Simon H.,



         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. The aim of this study is to analyse the recent sedimentation rates using the 210Pb 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. The total 210Pb content was measured via 210Po by alpha spectrometry, while supported 210Pb was measured by 226Ra (trough short life 222Rn daughters) with HPGe detectors. Heavy metals were determined by ICP-MS; from the 64 measured elements, only exceeding values of Al, As, Cd, Co, Cs, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Ni, Pb and Zn are discussed. After applying the CRS model, ages and sedimentation rates were calculated. The average sedimentation rate of the Cruhlig Lake is 0.21 ± 0.02 g/cm2y, Minimum values (0.05 ± 0.003 g/cm2y) are registered along the eastern shoreline of the lake before 1913, while maximum values are recorded due to the flooding in 2006 in the western side (1.34 ± 0.12 g/cm2y). Recent sedimentation rates divide the lake into three areas: the secluded eastern near shore part (0.63 ± 0.07 g/cm2y), the centre of the lake (0.92 ± 0.05 g/cm2y) and the dynamic western area, where most sediment transport takes place (1.13 ± 0.01 g/cm2y). The sedimentation pattern proves this lake to be very sensitive to fluvial discharge fluctuations. The building of the Iron Gate dams (1972 and 1985) 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. Values for Cd, Co, Cr, Hg, Pb and Zn are up to five times higher in 1980 ± 5 y in the eastern part of the lake, while Cd, Co, Cr and Ni are twice as high as the values measured for the marine substrate. Values of As show increasing of up to 150% in 2006 ± 2 y throughout the whole surface of the lake.


Journal of Environmental Radioactivity 153: 167-175. DOI. 10.1016/j.jenvrad.2015.12.020


Anthropic influences on the sedimentation rates of lakes situated in different geographic areas


Simon H., Kelemen Sz.,Begy R.-Cs.,




         The aim of this study is to determine the effects of natural and anthropic events occurring in the last 30 years in the catchment areas of four Romanian lakes (St. Anna Lake, Red Lake, Vârșolț Lake and Matița Lake) originating from four different geomorphologic areas. A total of eleven sediment cores have been processed for age and sedimentation rate determination using the 210Pb dating method. Total 210Pb was measured via alpha spectrometry by 210Po using PIPS detectors, while supported 210Pb was measured by226Ra using HPGe detectors. Ages and sedimentation rates were calculated using the CRS model. The values of the sedimentation rates have grown multiply in the last three decades: 2.66 times in case of the St. Anna Lake (from 0.06 ± 0.01 g/cm2y to 0.16 ± 0.02 g/cm2y), up to 6.72 times in case of Red Lake (0.36 ± 0.04 g/cm2y to 2.42 ± 0.36 g/cm2y), 4.02 times in case of Vârșolț Lake (04 g/cm2y to 1.53 ± 0.18 g/cm2y) and up to 16.18 times in case of Matița Lake (0.27 ± 0.03 g/cm2y to 4.37 ± 0.32).


Journal of Environmental Radioactivity,


Atmospheric flux, transport and mass balance of 210Pb and 137Cs radiotracers in different regions of Romania


Begy R.-Cs., Kovacs T., Veres D., Simon H.,



         This study focuses on the determination of 210Pb and 137Cs fluxes from different areas in Transylvania, Romania and on the determination of transport and mass balance within the lacustrine system of Red Lake. In order to achieve this, samples were taken from six different locations (Bihor County area, Ighiel area, Red Lake area, Mluha Peatbog, Mohos Peatbog and Zanoaga Rosie Peat bog in the Semenic Mountains) throughout Romania, these being compared to the values of the Danube Delta area. The activity concentrations of the soil samples were measured by gamma spectrometry (HPGe detector) for both 210Pbtotal, 210Pbsup (226Ra) and 137Cs, while peat samples were measured by both alpha (210Po) spectrometry (PIPS detectors) as well. The mean value for the 210Pb flux was measured in the Danube Delta region (42±8 Bq m−2 yr−1), while the highest was measured in the Semenic Peatbog (227±54 Bq m−2 yr−1); the average being 132±8 Bq m−2 yr−1. 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. In case of the Red Lake, from the total inventory of 410±23 Bq m−2yr−1 in the sediments, the loss by outflows is 100±12 Bq m−2 yr−1, the catchment to lake transfer factor being 0.84%.


Applied Radiation and Isotopes 111: 31-39.DOI: 10.1016/j.apradiso.2016.02.008



An improved procedure for the determination of 210Po by alpha spectrometry in sediments samples from Danube Delta


Robert Cs. Begy, Oana A. Dumitru, Hedvig Simon, Ionela Steopoaie



      The aim of this work is to find the optimal procedure for 210Po leaching from sediment samples. An improved method is described, the optimization consisting in a substantial reduction of leaching time. The method was tested on IAEA standard reference materials and compared with the classical procedure. The repeatability was estimated by analyzing seven duplicates of IAEA 385 Irish Sea sediment. However, the results are satisfactory only when the method is applied for sediments with high organic content. For silicates, a mixture of three acids was used for a complete digestion


Journal of Radioanalytical and Nuclear Chemistry



 Geochronology of Danube Delta sediments

The PN-II-RU-TE-2012-3-0351 project


 Robert-Csaba BEGY1*, Andra IURIAN, Oana DUMITRU, Hedvig SIMON, Szabocs KELEMEN




         It is highly important to know the geochronology of the lakes and streams of the Danube Delta, in          order to determine the sediment deposition rate. Several lakes are being investigated; physical          parameters and radiometric dating are being applied in order to determine the sedimentation p         atterns and rates of deltaic sediments. The used radionuclides are 210Po (210Pb) for alpha-         spectrometry with preliminary sample mineralisation and spontaneous deposition, and direct 137Cs          measurements using gamma-spectrometry. The sediment contaminations will also be analysed.


Keywords: Danube Delta, sediment, geochronology


Full text(sent to Studia Ambientum)






 Robert-Csaba BEGY, Hedvig SIMON, Szabolcs KELEMEN, Edina REIZER & Luminița PREOTEASA




           The 210Pb radiometric dating method was applied in order to determine the sedimentation rates of a northern Danube Delta lake (Merhei Lake) using α and γ spectrometry for assessing the radionuclides of interest. Another objective is to measure the geochronology of each sediment layer and to determine the dynamics of the characteristic sedimentation processes. The Danube Delta is the second largest river delta in Europe, having an approximate surface of 4152 km2. The Danube branches into three main distributaries into the delta: Chilia, Sulina and Sfântul Gheorghe. Two sediment cores (one from the close proximity of the estuary and another one from a more secluded area) were taken from a northern lake, namely Merhei Lake, formed between the Chilia and Sulina branches. The sedimentation rate was measured by 210Pb using its α emitting progeny, 210Po, for determining the solid discharge of the delta branches and, respectively, the spacial and temporal variations; while 226Ra (determining the supported and unsupported 210Pb content of the sediments) was determined using high resolution γ spectrometry. The sediments have been dated up to 1885, having average mass sedimentation rates of 0.30 ± 0.04 g/cm2y and linear sedimentation rates of 0.68 ± 0.18 cm/y. The sediment is transported throughout the lake, so the more secluded part of the lake has at some depths up to twenty times more sediment intake than the one near the estuary.



 Keywords: sedimentation rate, 210Pb dating method, Danube Delta



 Carpathian Journal of Earth and Environmental Sciences, November 2015, Vol. 10, No 4, p. 189 - 192

Faculty of Environmental Science and Engeneering


FANTANELE str. nr. 30

postal code :           400294
Telefon :        +40264 30 70 30

Fax :               +40264 30 70 32



Project Leader:

Lect. dr. Begy Robert-Csaba


Radionuclides As tracers of the Anthropic influence on the Danube Delta sedimentary processes