Vulnerability of the soil to human induced erosion processes varies in time and space depending on the climate, geology, type and term of land use. Scientific-based current state of knowledge on anthropic impact on forested areas in Romania is limited. For highlighting the environment erosion process and for reconstructing these processed for the recent past, aquatic sediments are the perfect environment. 210Pb dating method is a valuable tool for studying the sedimentation rates of lakes over the last 150 years. Variable sedimentation rates in lake catchments are indicative for changes in land use. 210Pb dating method has been previously applied for the quantification of the effects of land use in other international studies, but such an approach has not been attempted so far in our country. Based on our previous experience with 210Pb dating method as well as natural radioactivity in general, in the current proposal we will investigate lacustrine sediments from Retezat and Parang Mountains, Carpathian Mountains, as well as from Transylvanian lowlands. Sedimentation rates will be quantified by 210Pb method and radionuclides such as 210Pb, 137Cs and 7Be will be used as tracers to highlight the effects of land use changes. Additionally, we propose a multi-proxy interdisciplinary approach which includes detailed geochemical and geophysical analyses of clastic sediment input (XRF, magnetic susceptibility, LOI, trace metals) and detailed analysis of paleoecological proxies (pollen, micro and macro charcoal). This combined radiometric dating/multi-proxy approach surmounts limitations of the traditional approach of separate identification of the sediment components based on the sedimentation rate modification when only chronological proxies are used, leading to the development of a laboratory procedure and a mathematical model for identification, separation and quantification of the anthropic footprints from natural climate change forcing in sedimentation processes.
Objectives
The first objective is the investigation on a high resolution time scale of the recent changes in sedimentation rate on high mountain lakes.
Selected lakes have been studied in order to construct an age depth model by using 14C chronology. This type of investigation covers the last 15ky but does not provide information about the last 150 years, when the major changes occurred in forestry. Changes occurred in these last 150 years will be studied in this project.
The second objective is to build an erosion model based on the data obtained by analyzing and mapping the erosion processes on the catchment of a lake located on lowland site from Transylvania for highlighting the impact of land use changes and obtaining evidence of the transportation of solid material from slopes into the sediments of the lake.
The third objective is the construction of a time scale for the erosion events using the data obtained on the catchment of the lowland lake. The erosion map does not provide the necessary information about the changes occurred in the catchment during the time when the land use changes happened. Thus in order to obtain a time scale for these events it is called for a proper investigation on the sedimentation rate in the catchment. Only an age depth model, along with the associated sedimentation rates and the erosion map represent a complex database for reconstruction the past erosion events.