Heavy metals
Use of plant protection substances
Surface water pollution with nutrients
Heavy metals
Raw materials for energy production resources and transport
fuels contain small amounts of heavy metals, which are released to
the air during combustion. The metals fall on the soil with dry
and wet deposition. In general, the heavy metal levels in Latvia
are at background levels.
Heavy metal concentrations in grain and potatoes are
significantly lower than the required maximum allowed levels given
in legislation.
Mean and maximum
concentrations of heavy metals in crops at monitoring sites,
1993-1999
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Use of plant protection substances
The impact of plant protection substances on the environment
and the associated risk of food products is difficult to assess,
since their toxicity as well as persistence and mobility in the
environment are extremely variable.
The concentrations of plant protection substances now utilized
are significantly higher than the concentration used in the
1980's. The amounts of chemical plant protection substance
presently applied are about 77% lower than the amounts applied in
1990. The land area treated with these substances also has
decreased.
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Surface water pollution with nutrients
The discharge of nutrients with runoff from agricultural land
is natural, and occurs most intensively between October and April.
Agricultural runoff promotes pollution of aquatic ecosystems with
nutrients. The discharge of nitrogen and phosphorus depends on
climatic and hydrological conditions, and differs between years.
Non-sustainable management, application of fertilizers, and
installation of land drainage systems increase nutrient runoff.
This type of pollution source is called diffuse. Nitrogen runoff
from agricultural land is about 4-17 kg/ha yearly, and phosphorus
runoff amounts to 0.05-0.5 kg/ha yearly. The Vienziemīte Station
represents the background level in Latvia, the Mellupīte Station
is in an area of non-intensive agriculture, and the Bērze Station
is surrounded by intensively used agricultural land.
The biggest source of agricultural pollution is poorly planned
manure management which creates concentrated pollution loads. The
concentrations of leached substances depend on the management of
storage and application, which often are practised without
consideration of environmental protection requirements. According
to the project for the Cabinet of Ministers Regulations On
Protection of Water and Soil From Nitrate Pollution Originating
From Agricultural Practise, and Increased Levels of Protection
from Nitrate Pollution for Particularly Sensitive Territories, the
allowed levels of applied organic fertilizer on agricultural land,
including manure left by grazing animals, do not exceed 170 kg
nitrogen per ha, which is equivalent to 1.7 animal units/ha.
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