Study of Heavy Metals Accumulation in Animal Bones of the 5th Millennium BC in Kurdistan Province

In today's world, the release of many heavy metals into the environment and their entry into the food chain has contaminated and the natural base of the mines and natural deposits of these metals has played a more important role in environmental pollution. It seems that in the prehistoric period (5th millennium BC) in the Kurdistan region, this type of contamination base has caused severe contamination in some products of prehistoric inhabitants. Geological surveys in the Kurdistan region have shown that high density of metal ions contaminate surface and groundwater and directly affect aquifers. This has caused of pollution and collapsed of environmental of the inhabitants of the fifth millennium. The archaeological excavations of Chehl Amiran Mound belonged to the 5th millennium BC in Kurdistan had done in 3 seasons, one of the achievements of excavations in Chehl Amiran Mound was the discovery of many animal bones in this habitat site, that were studied. The time of the establishment of this habitat based on Thermoluminescence tests goes back around 5,500 BC, which lasted until 1500 BC and then the site collapsed.In the chel amiran Habitat site, a large number of bone samples from various animals were found, from these samples, 21 bones belonging to different animals from the 5th millennium BC were tested. Also, a number of bone samples from contemporary cattle and sheep from the region were collected and they were evaluated for the comparison. It should be noted that these livestock had been fed freely from the vegetation grown in the same region. Samples were transferred to the laboratory independently after collection. The measurement of lead and cadmium values ​​of samples versus the standard was carried out by the Varian spectra AA220 atomic absorption (Australian fabrication). Recovery rate for each element was calculated by using the chemical Sample Reference LUTS-1 (NRCC) and was used to measure the elements separately. By using the standard solutions for each element the device was calibrated. The wavelengths were 217.0 nm and 228.8 nm, respectively, for readings the lead and cadmium. The findings of this study indicate that livestock in the chel amiran region were exposed to severe contamination with lead. The results of the samples of contemporary animals which living in the study area also confirmed that the contamination remains in the region. Therefore, the study of water, soil and plant resources of the excavated area is necessary to identify the origin of this contamination. In fact, it can be admitted that the main reason for this collapse is the presence of gypsum and copper deposits and possibly the presence of heavy and toxic metals in the ecosystem of the region. The poor soil of the region, and Proportional high elevation of the sea and the relative coldness of the climate, compare to other areas around, as well as the weakness of the pastures, are among the reasons for the unsteadiness of habitats during the prehistory time of the region. The area due to metal deposits does not have agricultural capability and the majority of livelihoods of residents based on livestock. It seems that one of the reasons for the collapse of the chel amiran habitat was the penetration of heavy metals and metals into the soil of the area, which has caused the soil to be poor, and damaged and had got the possibility of extensive agriculture. Therefore, after 1500 BC, the chelamiran habitat has collapsed forever and never even until present time been able to live in it. Therefore, with the assumption that despite the environmental stability and the gradual warming of the air and human access to domestication, Why, after the peak of the population of the Talvar Valley in the 5th millennium BC, suddenly the number of settlements was reduced and until the historical and Islamic periods never returning to the previous level, is a basic issue for a better understanding of the situation in this area. Thus, the destruction of the environment of the region by humans due to its double pressure could have caused such an occurrence .The present study was conducted to evaluate the levels of lead, arsenic and cadmium found in animal bones found in Talwar Dam in Bijar Township and compare it with contemporary samples obtained from domestic animals slaughtered in the same area, which seems that, environmental pollution has caused of population collapse in the Talvar Valley of Kurdistan Province.