title: Recent changes in Red Lake (Romania) sedimentation rate determined from depth profiles of 210Pb and 137Cs radioisotopes.
abstract: This work presents a first estimation of the sedimentation rate for the Red Lake (Romania). The sediment accumulation rates were determined by two well-known methods for recent sediment dating: (210)Pb and (137)Cs methods. Both techniques implied used the gamma emission of the above-mentioned radionuclides. The (210)Pb and (137)Cs concentrations in the sediment were measured using a gamma spectrometer with a HpGe detector, Gamma-X type. Activities ranging from 41+/-7 to 135+/-34Bq/kg were found for (210)Pb and from 3+/-0.5 to 1054+/-150Bq/kg for (137)Cs. The sediment profile indicates acceleration in sedimentation rate in the last 18 years. Thus, the sedimentation process for the Red Lake can be divided in two periods, the last 18 years, and respectively, the period before that. Using the Constant Rate of (210)Pb Supply method values between 0.18+/-0.04 and 1.85+/-0.5g/cm(2) year (0.32+/-0.08 and 2.83+/-0.7cm/year) were obtained. Considering both periods, an average sedimentation rate of 0.87+/-0.17g/cm(2) year (1.17cm/year) was calculated. Considering an average depth of 5.41m for the lake and the sedimentation rate estimated for the last 18 years, it could be estimated that the lake will disappear in 195 years.
authors.affiliation: Faculty of Environmental Science, Babes-Bolyai University, RO-400294 Cluj-Napoca, Romania. brobert23@yahoo.com
authors.forename: R
authors.initials: R
authors.lastname: Begy
authors.forename: C
authors.initials: C
authors.lastname: Cosma
authors.forename: A
authors.initials: A
authors.lastname: Timar
mesh_terms: D002588:Cesium Radioisotopes / Q000032:analysis*; D004784:Environmental Monitoring; D005618:Fresh Water / Q000737:chemistry*; D019015:Geologic Sediments / Q000737:chemistry*; D007700:Kinetics; D007856:Lead Radioisotopes / Q000032:analysis*; D055110:Radiometric Dating / Q000379:methods*; D014875:Water Pollutants, Radioactive
chemical_list: D002588:Cesium Radioisotopes; D007856:Lead Radioisotopes; D014875:Water Pollutants, Radioactive