POLLUTION LEVEL OF ECOLOGICALLY VULNERABLE AREAS AROUND KAJARAN TOWN AND WAYS OF THEIR IMPROVEMENT

Kajaran town is situated in the south-east of the Republic of Armenia in Syunik Marz. Developed mining and smelting industries can be observed in this area. This economic sphere is one of the main sources of soil pollution with heavy metals causing desertifi cation of soils. Taking into consideration the location of the main sources of pollution six the most risky sites in this area and an unpolluted site as a control were selected for the study of pollution by heavy metals. The content of metals was determined by means of ELAN 9000 ICP-MS System. Study results revealed the increase up to 17 times in contents of following metals: Co, Ni, Cu, Zn, Cr, Sr, Mo, Cd, Pb, As. Based on Geoaccumulation index (Igeo) classifi cation, the soils from all sites may be classifi ed between “practically uncontaminated” and “uncontaminated to moderate”. The pollution level for Cu (Igeo = 0.031-2.468) was higher than for other metals. The sites adjacent to Kajaran ore-dressing and processing enterprise are classifi ed as “moderately to strongly” contaminated by Cu. Experiments have led us to the assumption that pollution of soils with heavy metals in the studied territory is conditioned by human activities, particularly by mining and smelting industry.


Introduction
The prime emphasis among environmental advocates has always been the protection of human health, with the implicit recognition that human well-being is inextricably intertwined with the health and stability of natural ecosystems of which we form an integral part.Some of today's most prevalent ills are increasingly blamed on toxic environmental contaminants -heavy metals that become pollutants as a result of previous industrial, mining or other activities [12].Contamination of soils by heavy metals is a signifi cant problem, which leads to negative infl uence on soil characteristics and limitation of productive and environmental functions [2,6,7,9,10,11,[13][14][15][16].The accumulation of these contaminants in the environment has become a concern due to the health risks to humans and animals [4,8,17].
Mining industry is a developed branch of the Armenian economy.Since the last decades of the 20th century, mining and benefi ciation of a variety of minerals, in particular copper and gold, have been the driving force behind economic development, particularly in RA Marzes (administrative districts) of Syunik and Lori.
The aim of our studies was the evaluation of soil pollution level (particularly by heavy metals) of ecologically vulnerable mining territories around Kajaran town in the RA Marz of Syunik and suggestion of ways for their improvement.The problem under study in this region is very urgent and actual because it concerns the preservation of sensitive natural resources, prevention of inadmissible contamination of food products and the protection of the health of inhabitants in this region.Appropriate management of surroundings of open mines, active tailing dams, sites adjacent to ore-dressing and processing enterprises as well as suggestion of ways for preventing pollution in the surrounding territories are very important.Preventing heavy metal pollution is critical because the cleaning of contaminated soils is extremely expensive and diffi cult.

Materials and methods
The lands of the area belong to the type of mountain cambisol.In Armenia this soil type is distributed 500-1700 meters above sea level, and on arid southern slopes it reaches up to 2400 meters [1,3].The objective of this research was the analysis of soils of six the most risky sites of this region (Figure 1).
It should be noted that the tailing dam of Artsvanik is rather far from Kajaran town nevertheless this site was also chosen as far as it is now the only active tailing dam of the enterprise.
Taking into account the above-mentioned, 18 sections of only horizon A of soil (0-20 cm) were performed in selected sites.The control section on distance 4 km from enterprise in a western ward direction was also done (approximately on distance 1 km westward from Kajaran village).Sections were performed manually.The sampling of soils was carried out in a traditional way, well-known in soil science.All labware and sampling apparatus were pre-soaked in 5% nitric acid solution followed by distilled water for a day prior to sampling for removing trace concentrations of metals.
Samples of soils were taken from a depth of 0-20 cm at 5 m intervals on a grid measuring 20 m x 20 m and with the center point of the grid at the sample location.After homogenization and removal of unwanted content (stones, plant material etc.) samples were air-dried at room temperature, ground, sieved to pass a 1 mm mesh and stored in an all-glass jar for analysis of their properties.
The content of heavy metals was determined by means of ELAN 9000 ICP Mass Spectrometer (Perkin Elmer, Inc). the sites adjacent to Kajaran ore-dressing and processing enterprise (samples no.1-6), 2.
To quantify the degree of pollution of soils with heavy metals the Geoaccumulation index, I geo , was used [5]: where: C n -measured concentration of heavy metals in the soils from risky sites (μg/g); B n -background value of heavy metals in the soil from control section (μg/g); 1.5 -background matrix correction factor.
The coordinates of sampling sites having been recorded with GPS receiver as well as their pollution with heavy metals have been described in registration book for general evaluation of soil pollution level.
The content (μg/g) of some heavy metals in the studied samples of soil is presented in Table 1.Since the contents of metals and non-metals in soils are specifi c and depend on the compound of rocks producing the soil and the conditions of soil formation, for determination of pollution level the obtained results were compared with control sample which was considered as a background.Our study revealed the appreciable increase (1.5 to 17 times) in contents of following heavy metals: Co (samples no. 4, 7-9, 10, 16, 17), Ni (samples no.7-11), Cu (samples no.1-8, 14-18), Zn (samples no.6-9, 14, 16), Cr (samples no. 7, 9-11, 15, 18), Sr (samples no. 4, 6-8, 13, 14, 16), Mo (samples no.3-6, 18), Cd (samples no. 4, 5, 14, 18), Pb (samples no. 1, 7, 14), As (samples no. 5, 7, 9, 10).Compared to the control sample the signifi cant increase (approximately 17 times) in the content of heavy metals was observed only for copper which was due to the high content of this metal in ores (Table 2).In general the soil samples no.1-6, 8, 14, 16-18 were highly polluted by Cu and to some extent -by other metals, while the sample 12 was unpolluted.It should be noted that such kind of pollution of soils with heavy metals in studied territory is directly due to human activities, particularly to mining and smelting industry.The variation of high pollution with Cu and some heavy metals near the open mine and in territories that are adjacent to enterprise is due to the character of industrial activities, moving direction of airstreams as well as physical-chemical peculiarities of soils.According to classifi cation the soil from site 12 is the least polluted with the metals.The low rate of soil pollution in the surroundings of Artsvanik tailing dam is conditioned by correct exploitation of tailing dam.
As was mentioned above, comparatively high rate of soil pollution was also observed near the no operating recultivated tailing dams of Pkhrut, Darazam and Voghji.Although the content of copper considering as main pollutant was small in these recultivated soils other heavy metals (Co, Ni, Zn, Sr, Pb, Cr, As) by their content exceeded control samples 1.5 and more times.Thereby the inhabitants of these territories are not recommended to use these territories for agricultural purposes even as pastures and hayfi elds.

Conclusions
Taking into consideration the above-mentioned it is necessary to implement recultivation activities in the areas around Kajaran town that constitute the main source of pollution by heavy metals.The recultivation works are advisable to implement by the method of hydroseeding which is considered as a subtype of biological recultivation.The main goal of biological recultivation is the recovery of soil formation natural process, the stimulation of soil self-purifi cation properties and biocenosis self-recovery process.Biological recultivation results in the formation of a landscape with satisfactory biodiversity on disturbed and polluted areas.
As the area of our studies is polluted especially with heavy metals it is also desirable to add to seed mixture using in hydroseeding method the seeds of plants which have the ability of removing selectively some heavy metals from the soil (rose (Cu, Fe), chalk plant (Cu), violet, penny cress (Zn), joint weed (Zn, Pb, Cd), mustard (Pb, Cr), hibiscus (Co), buckwheat (Ni)) making the process of recultivation more effective.
In addition to the above-mentioned approaches it is also suggested using ameliorants, particularly the mixture of organic fertilizers (manure, biohumus) and natural ameliorants (zeolite, dacite tuff) for utilization of heavy metals or at least for reducing their toxic impact on living organisms and the environment on the whole.It is scientifi cally proved that it is possible to improve the condition of soils polluted by heavy metals and to decrease the content of mobile forms of these elements by the joint use of natural ameliorants and organic fertilizers.