Case Study Experiment - immobilization of heavy metals using soil amendments
The researchers tested the effectiveness of different soil amendements to reduce the heavy metals mobility in soil and the uptake by plants.
|Factory site, Copsca Mica|
The main results from the experimental field were:
- The highest increase in pH values was for soil treated with Na-bentonite (7.16) compared with the control (5.18).
- In both experimental years, concentrations of available cadmium, lead and zinc decreased significantly with the application of amendments, and they followed the order (highest to lowest): control > natural zeolite > manure > Na-bentonite > dolomite.
- Compared with the control all treatments had statistically significant effects on metals accumulation in biomass but the highest decrease of metal content in the plant was after dolomite application.
The Case Study area is located in Sibiu county, around the most important factory for processing of non-ferrous ores – Copsa Mica. Copsa Mica is located in the Valley of Târnava Mare River, in north of Sibiu, 33 km east of Blaj and 12 km southwest of Medias. Copsa Mica region has temperate continental clime with an average annual temperature of 8.6°C. Long-term annual precipitation ranges from 900 to 1300mm. The population in 2010 was 5573, down 13% from the population in 1989. The main soil types in the area are Haplic Regosols and/or Regosols; Albic Luvisols; Haplic Phaeozems; and Fluvisols, whilst the main crops are maize, wheat, oat, potatoes and alfalfa. Also, livestock, dairy cow, sheep and horses are also evident. The main pollution is caused by S.C. Sometra S.A., a metallurgical plant.
Location and general view of the Copsa Mica
Main soil threat
Copşa Mică is a city developed around two industrial areas, both with high pollutant potential. The main pollutants identified in this area were cadmium, copper, lead and zinc. Moreover, this city was presented in Blacksmith Institute and Green Cross Switzerland Report 2012 - "World's Worst Polluted Places" as examples of high cadmium pollution (www.worstpolluted.org).
Other soil threats
Soil erosion is a problem as the polluted area is characterized by a very complex geomorphological pattern, with slopes of various different gradients, ridges and plateaus. Pollutant emissions from non-ferous metallurgical factory are also responsible for the decrease of soil structural stability and soil pH. Due to the lithological susceptibility of land to erosion, the naturally developed sheet and rill or gully erosion processes have intensified.
Obsolete technologies and the lack of adequate filtering for the chimney stacks resulted in: a.) significant accumulation of heavy metals in arable land, the values being excessive to the maximum plough layer; b.) increase of heavy metal content in vegetation and crops; c.) decrease of soil structural stability; d.) increase of soil acidity due to pollution with sulphur oxides; and e.) disturbance of microbiological activity with negative consequences on organic matter quality and nutrient supply. The polluted areas where the pollutant content in soil (0-20cm) exceeds the alert thresholds for sensitive use of land, according to Vrînceanu et al. (2010), are: 7040 ha – for zinc (content in soil exceeding 300 mg/kg); 10320 ha – for cadmium (content in soil exceeding 3 mg/kg); 22565 ha – for lead (content in soil exceeding 50 mg/kg).
In Romania, most work concerning remediation of heavy metals polluted soil has focused on immobilization of these pollutants using different types of inorganic additives, such as zeolitic tuff, bentonite, volcanic tuff, and biosolids. Although the situation is well documented, and there have been some attempts to remediate these soils, until now, no feasible solution for the decontamination of this large region has been found. In Romania, these technologies for remediation of polluted soils are not yet commercially available, possibly due to the inadequate awareness of their advantages and principles of operation. The effectiveness of the amendments could be assessed in several different ways including chemical methods (e.g. selective and sequential chemical extractions, adsorption/desorption isotherms, long-term leaching) and biological (e.g. plant growth and dry-matter yield, plant metabolism, etc.).
Special focus will be given to identification of the most efficient low-cost soil amendments that could be used for remediation of polluted soil from the Copsa Mica area. An understanding of the forms of contaminants present in the soil can be used to make reliable predictions about sustainability of the in situ immobilization. Further, the results of our studies could be used to quantify the underlying economics, as a support for public acceptance and to convince policymakers and stakeholders.
Geology & Soils
Soils from Copşa Mică have been formed in varied conditions of relief with morphologic characteristics, which succeed on vertical, from mountains, hills, and depressions. The main soil types in the area are Haplic Regosols and/or Regosols; Albic Luvisols; Haplic Phaeozems; Eutricambosols and Fluvisols. In the bottom land area of Târnava Mare River are developing Fluvisol, and in the terrace and hill areas prevail Eutricambosol and Phaeozem types. The Fluvisol type develops on the fluvial parental material, being manifesting as sands and gravel in alternation with centimetre levels of clay. The underground water level can be found at 2 m of soil profile and can influence its formation. Within the soil profile, the water drainage is very good. The Phaeozem type has a considerable development, especially in the inferior part of the hill and terrace areas, at north and south of Copşa Mică area. The relief is weakly inclined, 20-30°. The parental material is manifesting as marls, clays and Pannonian siltstone (Damian et al., 2008).
Soil groups according to the FAO classification (left) and land use in the Case Study (right) Source: JRC
According to data from the Land Parcel Identification System (LPIS) provided by Sibiu County Center of the Agency for Payments and Intervention in Agriculture (2012), arable crops, located mainly in the lowlands, cover 60.4% of the total area (2,818.6 ha), and grassland covers 34.9% (1,627.3 ha). Orchards and vineyards represent a very small proportion of the total cultivated area, only 2.3% (106 ha) and 2.4% (110.3 ha) respectively. Deforestation has led to the formation of pastures predominantly characterised by species of Festuca rubra, Poa pratensis, Agrostis tenuis, and having a moderate grazing value. In spontaneous vegetation, species like Xanthium strumarium, Calamagrostis pseudophragmites, Asclepias syriaca, Vernbascum phlomoides, Phragmites australis, etc. were identified. Crops are cultivated both on well-drained floodplains as well as on terraces. The main cultivated species in the area are: wheat (Triticum aestivum ssp. Vulgare), oats (Avena sativa), maize (Zea mays) potatoes (Solanum tuberosum), sugar beet (Beta vulgaris var. Saccharifera), beans (Phaseolus vulgaris), peas (Pisum sativum) and vegetables: carrot (Daucus carota), parsley (Petroselinum hortense), and celery (Apium graveolens), all at a low yield due to pollution.
General view of agricultural land from Copşa Mică (Photo: D.M. Motelica).
The climate in the Case Study is temperate and continental, with four distinct seasons. Available records indicated that the annual average temperature is 9.1 °C. The coldest month is January when average monthly temperature is -3.3 °C. Regarding rainfall is noticed that there is a distribution by type of summer rainfall (about 60% of the annual precipitation occurs during the summer), with the maximum record in June (93 mm). According to information from ATEAM database, the mean annual precipitation ranges between 397 mm and 838 mm (see below). Air circulation is mainly oriented in the NE – SW direction. Characteristic of the Case Study are periods of calm atmosphere (64%), which causes stagnation of air masses and deposition of pollutants in the basin of Târnava Mare River. Also, air masses are channelled along Târnava Mare River and Vista River.
Annual precipitation / average temperature (left) and average monthly precipitation/temperature (right) at Copşa Mică area (1961-2000 period of record)
Hydrologically, the area belongs to the Mures River basin with the main tributary Târnava Mare River. The territory is traversed by the Târnava Mare, from East to West, the largest collector of surface waters. The most important tributary is the Visa River. A number of temporary streams are also met in the area.
Drivers and Pressures
In Romania, chemical pollution of soils is affecting approximately 0.9 Mha of soil, of which 0.2 Mha are affected by excessive pollution. Adverse effects are particularly strong related to pollution by heavy metals (Cu, Zn, Pb and Cd) and sulphur dioxide, identified especially in Baia Mare, Zlatna and Copșa Mică (Elekes, 2014). The major source of pollution in the Case Study has been the non-ferrous metallurgical plant of Copșa Mică, which was built in 1939 and initially produced zinc. After the World War II, the plant diversified products and increased its production capacity. In 2005 the metallurgical plant was specializing in both zinc and lead extraction from concentrated ores and in the recovery of the associated metals, such as cadmium, antimony, copper, gold and silver. Due to the numerous periods during which exceedance of the maximum admissible air pollution limits was reported, the company proceeded to replace facilities with a technologically modern sulphuric acid plant with a limited pollution impact on soil. In fact, since February 1st, 2010, plant production has temporarily stopped.
Contamination of soil in this area evolved mainly in two ways: 1) through the emissions of powders charged with suspended particles of heavy metals from point source pollution; 2) through wastes from the industrial spoil bank of the metallurgical factory. Point source emissions were transported by air masses and deposited on the land, leading to an increase of metal content in the top soil layer with dramatic effects on vegetation. Various researchers report that, from 1999 to 2008, the maximum annual deposits decreased in intensity, and their content in heavy metals (g/m2) also decreased from 315.02 to 5.90 for zinc, from 191.56 to 3.69 for lead, and from 2.79 to 0.008 for cadmium (Lăcătușu and Lăcătușu, 2010). The spoil bank is situated W-NW of the town, on the left bank of the Târnava Mare river, upstream of the junction of the Visa River. The spoil bank has an estimated area of 192,308 m2 and a storage volume of 2,000,000 m3. In 2006, it contained 3,150,000 t of wastes consisting of pyrite ashes, clinker, building materials and furnace slag. The nature of these materials allows an easy percolation of meteoric waters (Comănescu et al., 2010). The heavy metal contamination in the study area led to a significant decrease of biomass production, acidification of soil, decrease of organic matter content in the soil as well as to the physical degradation of soil.
The reduction of the activities of the industrial platform triggered a large scale migration towards the rural areas surrounding Copșa Mică. Small landowners in the neighbouring villages still use the land for subsistence agriculture, even though it is polluted, due to lack of awareness and poverty. The agricultural use of the land presents a risk for population health and also reduces the available options for soil remediation. Finally, due to both low soil fertility (as a result of contamination) and lack of financial resources, there is land abandonment.
Status of soil threat
Soil degradation in the study area is a result of the combination of natural factors (high declivities, friable rocks) with anthropogenic ones (deforestations, overgrazing, heavy metal and black carbon soot pollution). The process is amplified by the contribution of airborne and waterborne pollutants, which also end up in soil (Comănescu et al., 2010). The main soil threat is posed by heavy metal contamination. The mismanagement of the non-ferrous metallurgical activities of the Copşa Mică industrial platform without taking in account the environmental damage, lead to a historical accumulation of heavy metals (Cd, Zn and Pb) in the soil. Heavy metal content in the soil varies significantly depending on soil type, topography and predominant wind direction. According with results obtained in previous research projects (Vrinceanu et al. 2010), in 2005 polluted areas where the pollutant content in soil (0-20 cm) exceeds the alert thresholds for sensitive use of land are: 7,040 ha – for zinc (content in soil exceeding 300 mg/kg); 10,320 ha – for cadmium (content in soil exceeding 3 mg/kg); 22,565 ha – for lead (content in soil exceeding 50 mg/kg). Data from previous research studies indicate that the polluted land area, assessed during 1991-1993, to 21,875 ha, was very close to that reported for 2005, equal to 22,565 ha. The difference of only 690 ha, showed a slight increase in the polluted area in the time since the year 1991 to 2005, which demonstrates a systematic reduction in the pollution intensity over time (Lăcătușu and Lăcătușu, 2010).
Spatial distribution of cadmium and lead in soil around Copşa Mică
Maps on the current state of land use, soil degradation and soil conservation in the case study area have been produced using the WOCAT (World Overview of Conservation Approaches and Technologies) methodology
The steps of this process are as follows:
1) The area to be mapped is divided into distinctive land use systems (LUS).
2) The team gathers the necessary data on soil degradation and conservation for each LUS using a standardised questionnaire, in close consultation with local land users, and supported where possible by remote sensing or field data.
3) For each LUS, the soil degradation type, extent, degree, impact on ecosystem services, direct and indirect causes of degradation, as well as all soil conservation practices, are determined.
4) Once collected, the data is entered in the on-line WOCAT-QM Mapping Database from which various maps can be generated.
Following the principles of all WOCAT questionnaires, the collected data are largely qualitative, based on expert opinion and consultation of land users. This allows a rapid and broad spatial assessment of soil degradation and conservation/SLM, including information on the causes and impacts of degradation and soil conservation on ecosystem services.
More details about the methodology used to produce these maps and their interpretation can be found here.
Land Use (click on maps to expand)
The degree of degradation reflects the intensity of the degradation process, whilst the rate of degradation indicates the trend of degradation over a recent period of time (approximately 10 years).
Soil Conservation Measures
The "effectiveness" of conservation is defined in terms of how much it reduces the degree of degradation, or how well it is preventing degradation. The Effectiveness trend indicates whether over time a technology has increased in effectiveness.
Effects on soil threat on ecosystem functions
The following table lists the effects of soil contamination on the soil functions at the Copşa Mică area.
|Functions of soil||Explanation||Effect|
|Biomass production||Loss of agricultural and food production potential||H|
|Environmental interactions||The high mobility and bioavailability of these pollutants lead to contamination of groundwater and crops, having severe effects on human health.||H|
|Gene reservoir/ Biodiversity pool||Due to eco-toxicological effects of contamination, some species were affected.||M|
|Physical medium||Base for built development is affected (mainly due to landslides).||L|
|Source of raw materials||Raw material collection is not affected.||N|
|Carbon pool||Data on C stocks is not available||U|
|Cultural heritage||A number of heritage buildings have been affected by acid rain||L|
Effects of soil contamination on soil functions (N: None; L: Low; M: Medium; H: High; U: Unknown)
Administrative and socio-economic setting
In Romania, the Ministry of Environment and Climate Change (MMSC) is the main authority in charge of national environmental policy, water management and forestry management, fulfilling the role of state authority in charge of synthesis, coordination and control in these areas, directly or through specialized technical bodies and authorities or public institutions. According to the legislation, the MMSC is designated as the Managing Authority for the Sectoral Operational Programme for Environmental Infrastructure. The National Environmental Protection Agency (NEPA) under the MMSC, specializes in central public administration and is committed to implement policies and legislation on environmental protection through decentralized agencies that ensure all economic and social factors to comply with the Law of Environmental Protection, the National Action Program for Environmental and National Strategy for Sustainable Development. Soil contamination assessments are carried out according to Order 756/3.11.1997, which regulates the normal values, alert thresholds and action levels for different trace elements by land use type.
Population in Copşa Mică(Source: Sibiu County Department of Statistics)
and annual growth rate of Gross Domestic Product (GDP) volume for Romania and the Euro Area (Source: Eurostat).
As of 2011, the activities of the metallurgical factory have stopped and thus the input of contaminants in the soil has significantly decreased; nevertheless, the historical pollution continues to affect soils in the area.
Short term management
In order to control the pollution effects in the Copșa Mică area, some urgent measures are required: 1) measures to reduce the effects of heavy metal contamination, decreasing the input of these contaminants in the food chain; 2) measures for decontamination of the local polluted soils.
Soil and crop management methods can help prevent uptake of pollutants by plants, leaving them in the soil. Following management practices will not remove the heavy metals but will help to immobilize them in soil and reduce their transfer into the food chain: increasing the soil pH, using inorganic additives (limestone, dolomite, etc.), applying well fermented organic fertilizers, applying additives with high affinity for heavy metal cations (for in situ immobilization), selecting plants for use on contaminated soils, growing pollution resistant species especially the species without food value. Also very important are the ecological restoration activities to control erosion and landslides and the afforestation with species resistant to pollution (acacia, willow, hornbeam, etc.). Once metals are introduced in the soil, it is hard to eliminate them from the environment. Traditional treatments (chemical treatments, physical separation, high temperature treatment, etc.) for decontamination of soil polluted with heavy metals do exist but their cost is prohibitive for such a large contaminated area. An alternative method for decontamination is phytoremediation. Research has demonstrated that plants are effective in cleaning up contaminated soils. Phytoremediation is slower than traditional methods but cheaper.
Long term management
The particularities of the Case Study (large polluted area, historical pollution, large number of landowners, agricultural use of land, etc.), require the development of a long term management plan of land use in order to reduce the effects of heavy metal pollution and to increase the quality of life in this area. After the implementation of a remediation strategy, the systematic monitoring of key indicators and processes is very important. It is also important to improve the national legal framework in order to avoid the exploitation of highly polluted land for crop production and grazing and to provide alternative land use solutions for stakeholders.
Relevant end-users and local stakeholder groups include;
- Land users and farmers from polluted area.
- The main polluter – S.C. SOMETRA S.A. a Romanian metallurgical company.
- Local NGO's for Environmental Protection and local authorities.
- Regional Environmental Protection Agency Sibiu (REPA Sibiu).
There will be organization of a demonstrative field in polluted area where the most efficient immobilization treatments will be presented. Meetings will take place with local authrities, REPA Sibiu, farmers and NGO's. This will include the National Rural Development Programme, a training module concerning agricultural practices in polluted areas with measures to mitigate the pollution effects. A sociological study will aslo evaluate the social and economic status of the community from the affected area, and to assess the level of acceptance regarding the remediation measures proposed.
Gender and stakeholder workshops
At the first workshop, there were invited 7 women and 10 men, in order to achieve a good gender balance. Both men and women are land owners, providers of information to the general public, land managers, land workers and representatives of local authorities. Representatives of public institutions, whose role is to provide and monitorize fundings for landowners, were mainly men.
Regarding the choice of how to ensure sustainable management of land in order to reduce soil degradation in the region, participants had different options depending on their gender. Therefore women had considered as the most appropriate approach is "organizing training activities to increase understanding and acceptance related to land use change in order to reduce human exposure to contaminants through the food chain (replacing annual crops with biofuel crops, afforestation etc.) On the other hand, developing alternative sources of income for private individuals (tourism, manufacturing of raw materials, etc.) could be another solution to change the agricultural use of contaminated land. The alternative approach suggested by men, was an initiation of lobbying in order to improve the legal framework for contaminated land use (granting compensatory payments to landowners from contaminated areas, etc.).
Comănescu, l., Nedelea, A., Paisa, M., 2010. Soil pollution with heavy metals in the area of Copșa Mică town – Geographical considerations, Metalurgia International XV 4, 81-85.
Damian, F., Damian, Ghe., Lăcătușu, R., Iepure, Ghe., 2008. Heavy metals concentration of soils around Zlatna and Copsa Mica smelters Romania, Carpath. J. of Earth and Environmental Sciences, 3(2), 65-82.
Elekes, C.C., 2014. Assessment of historical heavy metal pollution of land in the proximity of industrial area of Targoviste, Romania, available at: http://dx.doi.org/1057772/58304.
Lăcătușu, R., Lăcătușu, A.R., 2010. Evolution of heavy metals pollution from Copșa Mică. Scientific Papers, UASVM Bucharest, Series A, LIII, 85-92 (http://agronomyjournal.usamv.ro/pdf/issue2010.pdf).
Suciu I., Cosma C., Todică M., Bolboacă S.D., Jäntschi L., 2008. Analysis of soil heavy metals pollution and pattern in Central Transylvania. International Journal of Molecular Science, 9, 434-453.
Vrinceanu, N.O., Dumitru, M., Motelica, D.M., Gamenț, E., 2010. Heavy metals behaviour in soil-plant system (in Romanian), ISBN 978-973-729-229-2, 204 pp