سنجش ميزان آلايندگي حاصل از فرسايش سازندها و معدنكاري در منطقه شيخ لر شمال غرب استان زنجان(انگوران)

Measurement of the contamination rate from the erosion of formations and also from the mining operations in the region of Sheikh Lar located in the Northwest of Zanjan Province

Talk a few years that in the study field of the environment there has been a consideration of a fundamental factor which is called under de title of stone contaminant coefficient (the rate of elements in rocks and formations). Using this factor itʹs possible to measure the amount of the contaminant potentially existent in the region which wouldnʹt be considered in the pollution measurement or in the evaluation of the sources of the pollution. Angouran mining area is located in the mountainous northwest of Iran and in the deal region of structural zones of Alborz-Azerbaijan, Zagros and Sanandaj-Sirjan. The oldest rocks of this area are attributed to the Late Precambrian and the youngest are in Pliocene age. To measure pollution levels, some samples of formations of the region were take and were analyzed. This evaluation showed that some formations, such as Qom Formation and upper red Formation and lower red Formation have not the potential for produce the pollution in the region but some others have shown a high ability in create the pollution. On of the contaminator formations is the lead and zinc deposit of Angouran in age of Precambrian that is located in 25 kilometers from the city of Dandy which there is different comments about the true age of this collection. However this formation in its stone bed has the high values of the elements which balance threat the environmental equivalence of the region. This amount in the case of the elements such as lead and zinc (up 20000PPM) cadmium (4000PPM) and arsenic (10000PPM) is in a very worrying rate and also about the elements like manganese, copper and tin, are higher than environmental standards. To ensure more, there was obtained and tested also other examples from the agricultural and crops land as well as water resources in the border of formations and outcrops and other desired areas. Measurements showed a significant correlation between the amount of certain elements in the adjacent soil of formations and the desired outcrops there. This significant correlation is seen more clearly as much as that the agricultural soils of marginal areas of the deposit have amounts a considerable amount of these elements in them. Using this method the coefficient of the pollution of the each formation was determined and introduced. In general, the pollution coefficient of the formations of the region is low and proportional and the only exception is the Angouran lead and zinc deposit which in comparison whit the similar deposits, due to its size and its non-normative utilization, has a high stone pollution coefficients.