Sources of POP's
Pesticide consumption
POP's in natural
waters
POP's in fish
POP's in marine
organisms
POP's in drinking water
POP's in food products
Sources of POP's
Persistent organic pollutants are not natural products, but
they are produced by humans. Based on their source and application,
POP's can be divided into 3 smaller groups:
- pesticide (aldrin, DDT, dieldrin, endrin,
hexachlorocyclohexane, chlordane, chlordecone, mirex,
toxaphene);
- industrial and technical chemicals (hexachlorobenzene,
polychlorobiphenyls (PCB);
- by-products of high-temperature processes (polychlorinated
dibenzo-p-dioxins and dibenzofurans (PCDD/F).
Pesticide consumption
Agriculture is considered to be one of the most important
sources of POP emissions. About 4.6 million tonnes of pesticides,
or 3.15 kg pesticides per ha or crop field, are applied yearly in
the world. The changes in pesticide use in Latvia during recent
years indicate recent activity in management of crops and orchards,
but the load from pesticide application is low.
The pesticides that are now registered and allowed for use in
Latvia are new-generation plant protection products, which rapidly
decompose and completely inactivate during interaction with
climatic conditions and the soil. They do not belong to the POP
groups of pesticides which have been restricted or prohibited for
use in Latvia for a relatively long period of time.
Pressure indicator
Pesticide consumption in
Latvia,
1995-2000
| Year |
Area of land where applied
(1,000 ha) |
Consumed amount of pesticide (tonnes) |
Amount of active substance (tonnes) |
Consumption (kg/ha) |
| Pesticide |
Active substance |
| 1995 |
188.4 |
602.0 |
355.9 |
3.20 |
1.89 |
| 1996 |
259.3 |
631.6 |
359.9 |
2.44 |
1.39 |
| 1997 |
358.2 |
676.7 |
334.0 |
1.89 |
0.93 |
| 1998 |
450.3 |
776.9 |
369.8 |
1.73 |
0.82 |
| 1999 |
478.2 |
726.2 |
312.8 |
1.52 |
0.65 |
| 2000 |
446.7 |
761.5 |
328.0 |
1.71 |
0.73 |
Source: State Plant Protection
Service
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POP's in natural waters
During the 1990's, the Latvian Hydrometeorological
Agency conducted monitoring of DDT and hexachlorocyclohexane (including
lindane) in the five largest rivers of Latvia. The observed levels
of POP's were low: DDT from 0.006 µg/l (Lielupe) to 0.025 µg/l
(Gauja), and hexachlorocyclohexane (lindane) from 0.002 µg/l
(Lielupe) to 0.009 µg/l (Venta). This monitoring programme was
discontinued in 1999 due to lack of financing.
The presence of POPs in surface waters can be
explained by:
POP's in fish
To monitor the state of the aquatic environment,
scientists from the University of Latvia (in co-operation with the
University of Stockholm) measured the concentrations of POP's in
perch (State indicator). The PCB concentrations in
perch from different locations in the Baltic Sea ranged from
250-1000 ng/kg.
The PCB concentrations of perch sampled from the
lakes Sīksala, Engure, and Burtnieki were much lower (150-400 ng/kg)
than in perch from Lake Ķīšezers (2400 ng/kg). The main source of
POP pollutants is considered to be transboundary transport. The
concentrations of DDT and other POP in water have stabilized or are
significantly lower (by more than 40%), in comparison to the levels
in the 1970's. The concentrations of DDT and its metabolites in
Latvia rivers and lakes during 1985-1996 were 3-9 ng/l.
POP's in marine organisms
POP concentrations in marine organisms (State
indicator) in the Gulf of Rīga were 3-7 times higher than in those
living in the areas of the Kattegat Strait near Denmark, where there
is intensive exchange of water with the North Sea of the Atlantic
Ocean. Polycyclic aromatic hydrocarbons (PAH) are another type of
POP that poses a potential hazard to the Baltic Sea. These
pollutants are often recorded around the mouth of the Daugava River
and in the central part of the Gulf of Riga, where the main sources
of pollution are industry and transport (including intensive
transport by ship).
POP's in drinking water
The presence of pesticides, including POP, has not
been recorded in testing of centralized water supply systems.
Therefore, they are not included in regular monitoring
of drinking water.
POP's in food products
Testing of POP concentrations in various food
products in 2000 (119 samples) did not find the presence of dioxins
(State indicator), but PCB concentrations lower than 0.16 mg/kg,
were characteristic.
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