title: Sediment dynamics and heavy metal pollution history of the Cruhlig Lake (Danube Delta, Romania).
abstract: 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 (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. The total (210)Pb content was measured via (210)Po by alpha spectrometry, while supported (210)Pb was measured by (226)Ra (trough short life (222)Rn 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/cm(2)y, Minimum values (0.05 ± 0.003 g/cm(2)y) 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/cm(2)y). Recent sedimentation rates divide the lake into three areas: the secluded eastern near shore part (0.63 ± 0.07 g/cm(2)y), the centre of the lake (0.92 ± 0.05 g/cm(2)y) and the dynamic western area, where most sediment transport takes place (1.13 ± 0.01 g/cm(2)y). 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.
authors.affiliation: Babeş-Bolyai University, Faculty of Environmental Science and Engineering, 30 Fântânele Street, 400294, Cluj-Napoca, Romania; Interdisciplinary Research Institute on Bio-Nano-Science, Babes-Bolyai University, Treboniu Laurean 42, 400271 Cluj-Napoca, Romania. Electronic address: robert.begy@ubbcluj.ro.
authors.forename: Róbert-Csaba
authors.initials: RC
authors.lastname: Begy
authors.affiliation: University of Bucharest, Faculty of Geography, M. Kogălniceanu Blvd 36-46, Sector 5, 050107, Bucharest, Romania.
authors.forename: Luminita
authors.initials: L
authors.lastname: Preoteasa
authors.affiliation: Babeş-Bolyai University, Faculty of Environmental Science and Engineering, 30 Fântânele Street, 400294, Cluj-Napoca, Romania; Interdisciplinary Research Institute on Bio-Nano-Science, Babes-Bolyai University, Treboniu Laurean 42, 400271 Cluj-Napoca, Romania.
authors.forename: Alida
authors.initials: A
authors.lastname: Timar-Gabor
authors.affiliation: Babeş-Bolyai University, Faculty of Environmental Science and Engineering, 30 Fântânele Street, 400294, Cluj-Napoca, Romania.
authors.forename: Radu
authors.initials: R
authors.lastname: Mihăiescu
authors.affiliation: INCDO-INOE 2000, Research Institute for Analytical Instrumentation, ICIA, Cluj-Napoca, Romania.
authors.forename: Claudiu
authors.initials: C
authors.lastname: Tănăselia
authors.affiliation: Babeş-Bolyai University, Faculty of Environmental Science and Engineering, 30 Fântânele Street, 400294, Cluj-Napoca, Romania.
authors.forename: Szabolcs
authors.initials: S
authors.lastname: Kelemen
authors.affiliation: Babeş-Bolyai University, Faculty of Environmental Science and Engineering, 30 Fântânele Street, 400294, Cluj-Napoca, Romania.
authors.forename: Hedvig
authors.initials: H
authors.lastname: Simon
mesh_terms: D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry*; D060106:Lakes / Q000737:chemistry*; D007856:Lead Radioisotopes / Q000032:analysis*; D019216:Metals, Heavy / Q000032:analysis*; D011883:Radium / Q000032:analysis*; D012383:Romania; D013051:Spectrometry, Gamma; D014875:Water Pollutants, Radioactive / Q000032:analysis*
chemical_list: D007856:Lead Radioisotopes; D019216:Metals, Heavy; D014875:Water Pollutants, Radioactive; D011883:Radium
keywords: (210)Pb dating; Danube Delta; Heavy metal; Iron Gates; Sedimentation dynamics