Geochemical survey – an optimal solution in environmental assessment on local and regional scale

The quality of environment is extremely important for the human society development as well as for the entire biosphere equilibrium. In order to decipher the real status of an extended (regional) area and to rapport the print image of the local areas - subjects of development projects, a geochemical investigation have been performed in the Bucharest-Ilfov Region (Romania). The environmental factors (soil, underground and surface water and plants) evaluation on local or regional scale finds in geochemical survey (sampling, analyzing, mapping and reporting to national/international qualitative standards) an adequate solution. Taking into account the necessity of evaluating and monitoring the intensive populated areas, the exigency of such operation on height qualitative standards and at low costs increases. Admitting the European criteria to evaluate the water, soil and plants quality preservation as reasonable and averaging between national standards of EU community, the first observation regards the lowest possible price of sampling (proportional with sampling density, and increasing in case of difficult field access) and the highest accuracy/detection limits of final qualitative database acquisition. The necessary analytical diversity for a complex environmental investigation exceeds the classical routine of geological-geochemical one (usually limited to metalogenetic objectives) and includes various sophisticated categories (organic). For example the pesticides (a widespread category of biocides) investigation is an example of mostly refined and expensive analytical imperative. A systematic sampling must be performed at densities that ensure the representativeness on small surfaces (at least 4 soil samples/km², 1-2 underground water samples/km², 1 surface water sample/km², 2 samples of the same species of plant/km²) followed by physicalchemical analyses for specific categories (soil: As, Cd, Cr, Cu, Pb, Ni, Zn, Hg, mononuclear aromatic hydrocarbons and poli-aromatic hydrocarbons BTEX, PAH, insecticide organic chloride; vegetation: As, Cd, Cr, Cu, Pb, Ni, Zn, Hg; water: pH, conductivity, soluble oxygen, NH⁴⁺, NO₂, NO₃, PO₄, Cl, SO₄, Ca, Mg, Na, As, Ba, Cd, Cr, Cu, Co, Pb, Mn, Ni, Fe, Se, Zn, Hg, Te, Tl, Sn, U, V, phenols, BTEX, PAH, policlorurate biphenyl, organic-chloride insecticides. The mono-compound maps for each analyzed category were performed. Looking to the toxic and undesirable categories for each factor, lots of polluted areas have been identified as well as the pollutant sources.
   In order to evaluate less expensive solutions and the most relevant/representative mapping, the sampled/analyzed data were gradually reduced. The successive maps were analyzed in order to establish the proper sampling density for each chemical category. The quality of the environmental factors on the studied territory was affected by the lack of protection–prevention measures during the communist economy expansion and the massive post communist abandon of the industrial and agro-industrial units and by various polluting activities. This territory is undergoing an intensive developmental dynamic, the most intense of the entire national territory. Besides, the lack of a preliminary evaluation of the qualitative stage and the geographical extent of the polluting phenomena influences the environmental factors and will affect directly and essentially the quality of human life and socio-economic development. The elaboration of the cartographic image on the environmental pollution/preservation (the main purpose of this paper) supports both the necessary protection/prevention measures and the future socio-urban and cultural development plans for the target area (Bucharest-Ilfov). Meanwhile, it validates the geochemical systematic investigation as the main efficient and accurate methodology in assessment of environmental status of an area.