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Contamination of agricultural soils

Last update of indicator 20.12.2021

Indicator definition

The indicator describes the condition and development of soil contamination with hazardous substances.

Units

%

Metadata

Related policy documents and targets

Principles of the State Land Policy (2001)
The Slovak Government declares that the land of the Slovak Republic is the common wealth of the citizens of the state and the heritage of future generations. It is an essential and non-renewable resource, and it forms an integral part of Earth's ecosystems. It remains a basic environmental, ecological, economic and social potential of Slovakia, and must therefore be carefully protected from damage and unjustified reduction of its area and volume.
 

Rural Development Programme of SR 2014 - 2020 (2014)
Objective: Sustainable management of natural resources and adaptation to climate changes
Priority 4: Restoring, preserving and enhancing the ecosystems that are related to agriculture and forestry
13. Ensuring the protection of land from degradation
14: Preservation of agriculture in less favourable areas and efficient use of SR land resources
 

 

Key question

Have the limit values of hazardous substances in agricultural soils been observed?

Key messages

  • The development of soil contamination after 2005 has been very gradual. Comparing the individual monitoring cycles of the PMS-S (Partial monitoring System - Soil), there was no deterioration in the hygienic status of agricultural soils. Most of the hazardous substances in agricultural soils did not exceed the established limits, except for sites that had been contaminated in the past (in the vicinity of industrial plants, in the area of influence of geochemical anomalies).
  • In 2020, the main risk elements (Cd, Pb, Cu, Zn, Ni, As) were monitored, which recorded above-limit values in the previous monitoring cycle. Selected sites were analysed where contamination with at least one contaminant was determined after evaluation of the 4th sampling cycle (sampling year 2007). In the evaluated soil groups (chernozems and chernozems-brown soils on  loess of arable soils (AS), permanent grassland (PS) of rendzina, chernozems on carbonate fluvial sediments AS, chernozems on carbonate fluvial sediments AS, rendzinas AS, rendzinas, pararendzinas and carbonate lithosol PS, andosols on volcanics PS at the monitored contaminated sites, a positive trend in total Cd and a negative trend in total Pb and Zn was observed based on the observations made so far.
  • The latest hygienic survey of agricultural soils in the vicinity of the aluminium smelter in Žiar nad Hronom shows a slight reduction in the area of soil contaminated with fluorine, but the process of reducing the concentration of the monitored and evaluated element in the soil is only gradual. The average value of water-soluble fluorine in the soils opposite the aluminium smelter is still quite high (in 2020 a value of 20.30 mg.kg-1 was measured) and even today exceeds 4 times the value of the applicable hygiene limit for water-soluble fluorine in soils (5 mg.kg-1).
Change since 2005 Change since 2015 Last year-on-year change
emo_neutral emo_neutral emo_none
The soil contamination after 2005 was without major changes. Soils contaminated in the past are contaminated also at present. Since 2015, the content of most hazardous substances in agricultural soils has not
exceeded the specified limits.

The assessment of contamination of soils with hazardous substances throughout the monitoring network shall be carried out at 5 year intervals.

 

Summary assessment

Contamination of soils with hazardous substances

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Note: The map reflects the area and point contamination according to the limits resulting from the now expired Decision of the Ministry of Agriculture of the Slovak Republic on the maximum permissible values of harmful substances in the soil (number 531/1994-540).

Source: Atlas krajiny SR, Compiled by: SEA 

Detailed assessment

The evaluation of soil contamination is based on the assessment of hazardous substances content in the soil, especially of risk elements (Cd, Cr, Pb, Ni, Zn, Cu, As, Hg), F, PAH (polycyclic aromatic hydrocarbons), PCBs (polychlorinated biphenyls), which have a high biotoxicity degree for warm-blooded animals and humans.
Hazardous substances are present in the soil in different concentrations and in different forms. Their increased level may be caused due to various anthropogenic activities, such as: industry, energy, transport and agriculture, but often it is also typical for mountainous areas, so called natural geochemical anomalies.
 
In the 1st PMS-S monitoring cycle it was found that 69.5% of agricultural lands of the SR belonged to the category of non-contaminated ones, occurring primarily in areas with the most productive agricultural soils. 28.7% of land was marked as risk-bearing, exceeding A, A1 limit at least in one of risk elements. These soils were present mostly in mountainous areas with the provable high percentage of natural geochemical anomalies, and in areas with visible impact of global and regional emission transfer. Only 1.4% of soils belonged to the category of contaminated ones, exceeding B limit, and 0.4% to the category of extremely contaminated soils, exceeding C limit.


 
The most common contaminants of soil were Pb and Cd, less Ni and As. Extremely high values in categories B and C were reached by Hg, Cu, Cd, Pb, As locally, F, Cr. From organic pollutants that persist in the soil for longer, mainly polycyclic aromatic hydrocarbons (PAHs) are subject to monitoring. Other organic pollutants are more of "point" pollution character. Within the monitoring of SR soils, the highest levels of PAH were detected in particular in fluvial soils,  in the floodplains of larger rivers, in Mollic, locally also in the Luvisols and Cambisols and around industrial centres. Average content of polycyclic aromatic hydrocarbons (PAHs) in agricultural soils of SR was around 200 mg.kg-1.
Values ​​above 1,000 mg.kg-1 were only of local character (Žiar nad Hronom, Strážske, floodplain of the Danube and Morava). (Report on the State of SR Environment, 2002)

 

The results of the 2nd PMS-S monitoring cycle, with the sampling in 1997 showed that, compared to the 1st monitoring cycle, the hygiene condition of agricultural soils slightly improved, whereby the number of soils that exceeded the A1 reference limit for contaminated soils declined. The provable vertical migration of hazardous elements in the soil profile was recorded. (Monitoring of SR soils, 2002)

 

The results of the 3rd cycle, with the sampling in 2002 showed that the content of the majority of hazardous substances in selected agricultural soils did not exceed the limit specified at that time. For cadmium and lead, excessive limit values were ​​only in soils situated in higher altitudes (podzols, andosols), which might relate to remote transfer of emissions. In the 3rd monitoring cycle, out of 274 agricultural areas of 15 802 ha acreage in total, there were detected no above-limit agricultural areas by monitored pollutants (PAHs, PCBs, chlorinated hydrocarbons). (Report on the State of SR Environment, 2006).

 

The areal survey of soil contamination (ASSC) as a subsystem of PMS-S, closely linked to agrochemical soil testing system (AST), monitors contaminants in agricultural soils in the selected cadastral areas. The soils from these cadastral areas were selected on the basis of increased content of contaminants on an agricultural land, whose values were determined by the analysis in the 1st ASSC cycle, where at least one of the monitored parameters exceeded the limit value. The overview of above-limit hazardous substances in the agricultural soils of SR is presented in the following maps.

 
Overview of limit-exceeding values of lead in the SR agricultural soils for the period 2001-2005 (Pb limit = 30.00 mg/kg)

Source: CCTIA


Overview of limit-exceeding values of cadmium in the SR agricultural soils for the period 2001-2005 (Cd limit = 0,30 mg/kg)


Source: CCTIA



Overview of limit-exceeding values of mercury in the SR agricultural soils for the period 2001-2005 (Hg limit = 0,30 mg/kg)


Source: CCTIA



Overview of limit-exceeding values of arsenic in the SR agricultural soils for the period 2001-2005 (As limit = 5,00 mg/kg)


Source: CCTIA



Overview of limit-exceeding values of chromium in the SR agricultural soils for the period 2001-2005 (Cr limit = 10,00 mg/kg)

Source: CCTIA



Overview of limit-exceeding values of nickel in the SR agricultural soils for the period 2001-2005 (Ni limit = 10,00 mg/kg)


Source: CCTIA


Overview of limit-exceeding values of copper in the SR agricultural soils for the period 2001-2005 (Cu limit = 20,00 mg/kg)

Source: CCTIA


Overview of limit-exceeding values of zinc in the SR agricultural soils for the period 2001-2005 (Zn limit = 40,00 mg/kg)

Source: CCTIA
 

In case of monitored risk elements of 4th PMS-P monitoring cycle, with the sampling in 2007, there were indeed exceedances of statutory limits in some cases, more significantly increased content was recorded only for cadmium and lead mainly in lower river flows, which indicates their transport often from remote areas. The increased content of cadmium was detected in some rendzina, whereby organic matter and neutral soil reaction - in which the said element is less movable- contribute to its accumulation (Report on the State of SR Environment, 2012).
 

When comparing the 5th monitoring cycle (sampling year 2013) with the previous 4th monitoring cycle, there was a positive trend for total As and Cd and a negative trend for total Co, Cu, Ni and Zn at the monitored contaminated sites. Report on the State of SR Environment, 2018).

Samples of the 6th monitoring cycle were collected in 2018 and are being progressively processed and evaluated.

Contact

Ing. Beata Kročková, SAŽP, beata.krockova@sazp.sk

Related definitions:

Hazardous substances in the soil are elements and compounds the presence of which, from natural or anthropogenic sources in soils in certain concentration, directly or indirectly causes or may cause undesirable changes in physical properties, chemical properties and biological properties of the agricultural land.

Limit values of hazardous substances in soil are values defining the boundaries of maximum permissible contents of hazardous substances in agricultural soil.


Methodology:

Information on the state and development of contamination of agricultural land is provided by the Partial Monitoring System Soil (PMS-S), carried out by the National agricultural and food centre - the Research Institute for Soil Science and Conservation (NAFC-SSCRI ) at regular 5-year intervals, which takes place following the Agrochemical testing of soil (ATS), which is connected with the Areal survey of soil contamination (ASSC), and implemented by the Central Control and Testing Institute of Agriculture (CCTIA).

The 1st  monitoring cycle of PMS-S was realized in the years 1992-1996, with soil sampling in 1993 from 312 monitoring sites, 2nd cycle between the years 1997-2001, with soil sampling in 1997 from 318 monitoring sites, 3rd  cycle in the period 2002 - 2006, with soil sampling in 2002 from 318 monitoring sites. Risk elements for the first 3 monitoring cycles were evaluated according to the currently invalid Decision of the SR Ministry of Agriculture on maximum permissible values of harmful substances in the soil (no. 521/1994-540) of 1994 (see a table below).
 
Thresholds for certain hazardous substances in soils
Metals A A1 B C
As 29 5.0 30 50
Ba 500 x 1 000 2 000
Be 3 x 20 30
Cd 0.8 0.3 5 20
Co 20 x 50 300
Cr 130 10.0 250 800
Cu 36 20 100 500
Hg 0.3 x 2 10
Ni 35 10.0 100 500
Pb 85 30.0 150 600
Zn 140 40.0 500 3 000
Inorganic compounds        
F   (total) 5002) x 1 000 2 000
S   (sulphidic) 2 x 20 200
Aromatic compounds        
benzene x x 0.5 5
Ethyl benzene x x 5 50
toluene x x 3 30
Polycyclic aromatic hydrocarbons /PAH/        
naphthalene X x 5 50
phenantrene X x 10 100
anthracene X x 10 100
chlorinated hydrocarbons        
aliphatic chlorinated hydrocarbons (single) x x 5 50
chlorobenzenes (individual) x x 1 10
PCB (Total x x 1 10
Pesticides        
Organochlorinated (single) x x 0.5 5
non-chlorinated (total) x x 2 20
Others        
Mineral oils x x 500 1000
A –reference value means that the soil is not contaminated if the concentration of the element / compound is below this value. If the concentration achieves or exceeds this value, it means that the substance content is higher than phonic (background) values ​​for the given area, or above the values of sensitivity limit of the analytical analysis.
A1 – reference value related to the A value, valid for the determination of hazardous (harmful) substances in the 2M HNO3 extract.
B – indication value means that soil contamination was analytically demonstrated. Further study and site pollution control is required if the occurrence, area and concentration can have a negative impact on human health or other components of the environment.
C - the indication value for remediation means that if the concentration of substance element reaches this value, it is necessary to immediately carry out a definitive analytic mapping of damage extent in the relevant site, and decide on the corrective measure method. If the values ​​of concentration are in the range B and C, it is necessary to proceed in a similar manner.
 
4. So far the last completed monitoring cycle, which took place between 2007 - 2011 with sampling in 2007, was evaluated according to the currently invalid Annex no. 2 of the Act. 220/2004 Coll. on the Protection and use of agricultural land and on modification of the Act no. 245/2003 Coll. on the Integrated prevention and control of environmental pollution and on amending of certain laws, as amended (see a following table), which sets limit values of risk elements in agricultural soil.
 
 
Limit values of risk elements in agricultural soil set depending on the soil type and soil reaction value, and critical values of risk elements in a relation - agricultural land and plant
 
Risk element Limit values of risk elements in agricultural land
(in mg.kg-1 of dry matter, decomposition by Aqua regia, Hg total content)
Critical values of risk elements in a relation - agricultural land and plant
(in mg.kg-1 of dry matter, in  1 mol/l  leachate of ammonium nitrate, F in aqueous extract)
Sandy, loamy-sandy soil sandy- loamy, loamy soil clayey-loamy, clayey soil, clay
Arsenic (As) 10 25 30 0.4
Cadmium (Cd) 0.4 0.7 (0.4)* 1 (0.7)* 0.1
Cobalt (Co) 15 15 20 -
Chromium (Cr) 50 70 90 -
Copper (Cu) 30 60 70 1
Mercury (Hg) 0.15 0.5 0.75 -
Nickel (Ni) 40 50 (40)* 60 (50)* 1.5
Lead (Pb) 25 (70)* 70 115 (70)** 0.1
Selenium (Se) 0.25 0.4 0.6 -
Zinc (Zn) 100 150 (100)* 200 (150)* 2
Fluorine (F) 400 550 600 5
 
Note: The following data apply to the soil samples collected at the arable lands from the upper layer of 0.2 m thickness, air-dried to constant weight, * where the pH (KCl) is below 6, ** if the pH (KCl) is less than 5
 
In 2013, soil samples of 5th monitoring cycle were taken, which will be gradually processed and evaluated in accordance with Annex no. 7 to the Regulation no. 508/2004 Coll., by which the Section 27 of Act no. 220/2004 Coll. is  implemented, on the Protection and use of agricultural land, and on the modification of Act no. 245/2003 Coll. on Integrated prevention and control of environment pollution and on amendment of certain laws, which sets limit values of risk elements in agricultural soil and methods of their determination according to selected indicators.
 
NAFC-SSCRI maintains a central database from data obtained and provides the data thereof to the SR Ministry of Agriculture and Rural Development.


Data sources:

NAFC-SSCRI, CCTIA


Related indicators:


Linked references: