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Table 1. Data on Pb concentration in soil solutions of different soil types<br />

Soil characteristics<br />

Concentration of Pb<br />

Soil<br />

in solid phase, in solution,<br />

рН humus, % clay, %<br />

мg/kg<br />

mg/m3<br />

Podzols il-Fe 4.15 1.7 2.5 11.5 11.6<br />

Podzoluvisols 5.05 5.57 8.2 14 1.5<br />

Luvisols 5.95 4.8 8.5 28.5 3.25<br />

Grayzems 5.45 3.1 12.9 10 0.9<br />

Chernozems 7.7 4.7 17.8 29 0.6<br />

Fluvisols 7.6 4.1 19.8 30 0.8<br />

Depending on data available, there are some methods to account the water<br />

percolation flux. So, water balance equation can be calculated using the data on<br />

precipitation, both soil and interception evaporation as well as plant transpiration.<br />

If these data are in deficiency, simplified method of calculating based on<br />

approximation of total evapotranspiration as a linear function of mean air<br />

temperature can be applied accordingly to (Michalzik et al., 2001):<br />

Qle = P – (1+T/10 o )*0.25 (2)<br />

where: P - precipitation, [m/yr]; T - mean air temperature, [ o C].<br />

Both parameters are available through the regional or international climate<br />

database (for example, http://www.iwmi.org). Also, runoff data can be applied for<br />

this kind of calculating, especially for the areas with negative water balance when<br />

water leaching is during short period (mostly in the spring). Analysis of different<br />

calculations carried out using climate data (Medvedeva et al., 1983) have shown<br />

that if average data on precipitation and evapotranspiration have been used the<br />

value of water leaching equal to 190-200 mm/yr. On the other hand, Qle accounted<br />

using Eq.2 are in two times higher (about 400 mm) that are too high since total<br />

runoff values for the same area had been estimated in 115-125 mm (Zaslavskaja et<br />

al., 1983). So, metal leaching in forest ecosystems for area under investigation have<br />

been estimated in average from 1.0 up to 10 mg/m2.yr and higher depending on<br />

soil parameters. The main uncertainties have water percolation data.<br />

Removal by wood biomass growth. The following equation can be used to<br />

estimate metal outputs with biomass uptake:<br />

M up<br />

= f ru<br />

* Y * M hpp (3)<br />

where: fru – root uptake factor, to scale the net uptake in the root zone to the depth<br />

considered, [-]; Y – annual biomass growth, [kg/ha.yr]; Mhpp – metal content in the<br />

harvested parts (wood in the forest ecosystems), [mg/kg].<br />

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