Māris kļaviņŠ, azamat azizov, JĀnis zaļoksnis environment, pollution, development: the case of uzbekistan

Parti cularly high soil pollution is detected in cities, in surrounding 
areas of large industrial plants and along the highways. Each of the 
pollution sources depending on its type of activity, has a particular 
compo sition of chemical elements landing around it, formed by 
the chemical elements related to a fuel or the raw materials to 
be processed. Heavy metals enter the soil also due to agricultural 
activity.  As  the  agricultural  land  is  fertilized,  limed  and  treated 
with pesticides, heavy metals accumulate in the upper layer of soil. 
Subsequently, many agricultural soils have high heavy metal content.
Soil contamination problems are caused by irrigation of 
agricultural land. The problem is particularly acute in the areas 
where  the  sewage  water  is  used  for  watering  of  farmland.  As  a 
result, the soil is contaminated with Zn, Cu, Ni, Cr, Pb, Cd and Hg. 
Heavy metals are brought into the soil also with sewage sludge, 
which in many parts of the world is used to fertilize the agricultural 
and forest land. Therefore, Latvian and European Union law requires 
that before the use of sewage sludge as fertilizer, the soil and sewage 
sludge chemical composition analysis must be carried out. 
Heavy metals enter the 
lithosphere and mainly its 
upper layer – the soil – as 
a result of: 
 
Œ industrial activities; 
 
Œ agricultural activity, 
during fertilization and 
liming of the soil or 
irrigating territories; 
 
Œ waste storage 
(household and 
industrial); 
 
Œ burning of fossil fuels; 
 
Œ exploitation of the 
motor transport.

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200 
ENVIRONMENT, POLLUTION, DEVELOPMENT:  THE CASE OF UZBEKISTAN
As heavy metals reach the soil, they do not degrade, but slowly, 
with downward water flows, migrate deeper. The chemical elements 
in the soil participate in various chemical and biochemical reactions, 
creating new compounds, whose toxicity may increase in the soil. 
As  the  soil  pollution  increases  over  time,  the  risk  of  groundwater 
pollution with heavy metals rises. 
Increased concentration of heavy metals in the soil significantly 
affects  the  plants  and  groundwater  quality.  Toxic  concentration  of 
microelements in soil and their effect on plants is a very complex 
issue, because it is influenced by a great number of factors.