| Abstract [eng] |
Objectives: to perform Biržai region soil geochemical regionalism in accordance with geological-geophormalogical evidence, to establish geochemical field differences, evaluate resistance to polution technogenous chemical elements. Goals: 1. Summarize experience gained in previously accomplished geochemical regionalism in Lithuania. 2. Familiarize with geochemical mapping of Biržai region . 3. To explore geological (quaternary), geomorphologic and anthropocentric pollution conditions in Biržai region, according to this distinguish appropriate areas of soil and establish their geochemical field differences, by employing mathematical-statistical methods to verify extrication validity. 4. Applying factoring analysis Compose informative factors factoring significance maps – both for natural soil and city priming. 5. Determine different soil regions resistance to technogenic pollution by technogenous elements (Pb, Zn, Ag, Sn, Cu, Cr etc.), which represent their accumulation or immunity. Findings: 1. Two criteria were applied to Biržai area soil and priming geochemical regionalism: a) technogenic load rate; b) lithogenetical-geomorphological dependence of dirvodarinių rocks In Accordance to technogenic load rate area is divided into natural and two urbanized zones: Pasvalys and Biržai. By lithogenetical-geomorphological subordination in natural zone, 7 regions were identified: Vaškai, Lauksodis and Žeimelis morainic plains, Nemunėlis Radviliškis morainic limnoglacial plains, Linkuva morainic crest, Pasvalys limnoglacial plains, Saločiai limnoglacial plains, Pumpėnai morainic plains, Likėnai, Satkūnaiand Antašava morenic plains. 2. Main factors determining accumulation of chemical elements are: lithogenic and carbonaceous. The first one relates to clay’s percentage fraction in the soil, the second – carbonates and heavy minerals ratio in aleurite fraction. Technogenous elements such as Cr, Ni, Co, Zn are mainly associated with lithogenic factor,less associated elements are: Cu, Sn (Sorbtion on clay minerals). Following elements are associated with carbonaceous factor: Pb, Cu, Co, Zn (compose stable compounds and precipitate in alkaline environment). 3. With accordance to positive or negative values of factors, conclusion was made about argillaceous and carbonaceous of soil. Four conditional soil zones were distinguished: a) argillaceous and carbonaceous soils b) argillaceous and little carbonaceous soils c) little argillaceous and carbonaceous soils d) little argillaceous and little carbonaceous soils 4. Considering pollution of soil with technogenous it is required to consider not only relevant pollution, the one which is happening, but also into soil potential to accumulate chemical elements – potential pollution. Potential pollution is outlined by domination of varied zone factors values in geochemical region. 5. Majority of geochemical region’s soils are more or less argillaceous and carbonaceous, that means can accumulate more pollution elements. Especialy argillaceous and carbonaceous are soils of Vaškai, Lauksodis and Žeimelis morainic plains. Relevant pollution with technogenous elements (Pb-Mo-Zn-Co-P-Cu) is also evident here; these elements are associated with lithogenic and particularly carbonaceous association elements. Soils of Pumpėnai morainic plains are less argillaceous but more carbonaceous. Tchnogenous elements (Cu-Pb-Mn-Co-Ni) are related to carbonaceous association. Soils of Linkėnai, Satkūnai, Antašava morainic plains are distinguished in the context. They are less argillaceous and relatively little carbonaceous. Although techogenic pollution association (Pb-P-Ag-Ga-Zn-Cu) is evident, it is related to peaty sediments attribute to accumulate. |
