Monitoring of plant and soil pollution based on ionic impulsion

Abstract

Total pollution indexes for measuring heavy metal contamination of industrialized areas may be quickly estimated from selected metal partial indexes for soil (M-SPI) or plants (M-PPI). Partial pollution indexes for plants (or soils) are calculated by the formula M-PPI (or M-SPI) = 100 (I − Iunp)/(Itox −Iunp), where I = c i 1/ni is the ionic impulsion of the selected metal M, with oxidation number ni, for its actual plant (or soil) concentration ci,and Iunp and Itox, the ionic impulsions for unpolluted and toxid levels of the M in plants (or soils). The total pollution indexes were proposed by analogous formulae containing the sums of contributions of metals accumulated in roots (Pb, Cd, Co, Cr, Ni, Cu, Zn and also Fe for plants), without participation of macroconstituents (K, Mg, Ca, Na, and also Mn), accumulated in plant tops. Partial pollution indexes may also serve to show (i) deficiency or toxicity levels of plants (or soils) and (ii) associations between pollutants, easily detected by a numerical taxonomy's dendrogram. Using correlation coefficient techniques for the Bilbao (Spain) model zone, the total soil pollution index, SPI, may be calculated from Zn-SPI, Pb-SPI, Cu-SPI or Cu-PPI. The total plant pollution index, PPI, is similarly related to Fe-PPI or Zn-PPI, though some distortion is evident when the sampling point is close to specific industrial factories. The best estimation (without distortion) for monitoring total plant pollution index is based on the sum of contributions of essential elements (Fe, Cu, and Zn). This fact suggests the existence of defense mechanisms of plants for balancing both the uptake of toxic metals and deficiencies of essential constituents. Finally total pollution indexes may be used for the estimation of the number of pollutants with toxic levels in plants or soils.