تأثير نوع سنگ آذرين بر ميزان غلظت عناصر سنگين خاك هاي حاصل از آن در منطقه قروه استان كردستان

Evaluation type of igneous rock on trace elements concentration soils developed on them in Ghorveh region of Kurdistan province

به دليل تجمع عناصر سنگين در خاك و خطرات ناشي از آن، تشخيص نوع، منشأ و پراكندگي اين عناصر از اهميت ويژه اي برخوردار شده است. با توجه به اينكه مواد مادري يكي از عوامل اصلي در ارتباط با تركيب و ويژگي خاك است، در اين مطالعه به مقايسه ويژگي هاي متفاوت خاك هاي توسعه يافته بر روي مواد مادري متفاوت آذرين پرداخته شده است. در مجموع از 65 نقطه خاك سطحي از عمق 10-0 سانتي متري از منطقه اي به وسعت 260 كيلومتر مربع نمونه برداري صورت گرفت. از سنگ هاي غالب در منطقه تعداد 8 تا 10 نمونه سنگ و از سنگ هاي مادري كه وسعت كم تري دارند تعداد 6 تا 8 نمونه سنگ برداشته شد. پس از آماده سازي نمونه هاي خاك و سنگ، غلظت فلزات مس، روي، نيكل و كروم در نمونه هاي خاك روش (اسيد نيتريك 5 نرمال) و سنگ روش (اسيد فلوريدريك، نيتريك و كلريدريك غليظ) پس از عصاره گيري، با استفاده ازدستگاه جذب اتمي اندازه گيري شد. مقايسه ميانگين به روش دانكن در سطح احتمال 5 درصد نشان داد كه سنگ مادري (گابرو - بازالت) بجز با سنگ هاي مادري گرانيت پورفيري و گرانيت با ديگر واحد هاي سنگي در ميزان مس كل خاك اختلاف معني داري ندارد. براساس حد مجاز مشتخص شده براي كشور ايران در منطقه مورد مطالعه از لحاظ عنصر مس آلودگي وجود ندارد ؛ ولي بر اساس استاندارد كشور هلند 23/1 درصد از نمونه ها آلودگي نشان مي دهند؛ خاك هاي توسعه يافته بر روي سنگ مادري گرانيت پورفيري در ميزان غلظت روي كل با ديگر خاك هاي توسعه يافتته بر روي سنگ هاي مادري اختلاف معني داري دارند. بر اساس حد مشخص شده در كشور هلند و ايران در غلظت روي كل در خاك به ترتيب 4/7 و 1/5 درصد از نمونه ها آلودگي نشان مي دهند، ولي بر اساس استاندارد كشور استراليا آلودگي به اين عنصر وجود ندارد. خاك هاي توسعه يافته بر روي سنگ مادري (گابرو - بازالت) به استثناني خاك هاي توسعه يافته بر روي سنگ مادري (گابرو - بازالت) به استثناي خاك هاي توسعه يافته بر روس سنگ هاي مادري ديوريت گابرويي و گرانيت با ديگر خاك هاي توسعه يافته بر روي سنگ هاي مادري در ميزان غلظت نيكل كل خاك اختلاف معني داري ندارد. بر اساس حد مشتخص شده در كشور هلند، استراليا و ايران به ترتيب 96/8، 20/6 و 93/6 درصد از نمونه ها در خاك هاي منطقه آلودگي به عنصر نيكل دارند. همچنين خاك توسعه يافته بر روي سنگ مادري اسپيليت - بازالت با ديگر خاك هاي توسعه يافته بر روي سنگ هاي مادري در ميزان كروم كل خاك اختلاف معني داري دارد. 12/5 درصد از نمونه ها علظتي بيش از حداكثر غلظت مجاز كشور هلند و 57/8 درصد از نمونه ها غلظتي بيش از حداكثر غلظت مجاز كشور ايران را دارند. از لحاظ غني شدگي عناصر سنگين بعد از عنصر مس، عناصر كروم و نيكل بيش تر ين غني شدگي را درخاك هاي توسعه يافته بر روي مواد مادري منطقه مورد مطالعه دارند ؛همچنين همبستگي مثبت و معني داري بين غلظت مس موجود در مواد مادري و خاك هاي توسعه يافته بر روي آنها مشاهده شد كه نشان دهنده درجا بودن خاك ها و منشا توارثي اين عنصر در خاك است.

Introduction Soils and rocks natural main sources of heavy metals in the environment. Basic rocks called of igneous rocks, the crystallization of magma cooling. Geographic distribution of heavy elements, either naturally or through human activities will have issues and problems. These problems include lack of or are toxicity these elements. In recent years, many studies have done on the concentration of heavy metals in different parent materials and soils developed on them in the world. This research's has shown that the amount of heavy metals in the soil, depended to type of parent material, climate, topography and human activities. Heavy elements in most rocks in the Earth's crust and in soils that have been formed under different climatic conditions can be found. Parent rocks have decisive role in amount of trace elements in the soil. Often a direct correlation between the rocks and soils that are formed of parent materials existing from the point of view of heavy metals. Materials and Methods The study area with an area of 261 square kilometers located in the Kurdistan Province in the southern ghorveh city. This area between longitude 47 degrees and 36 minutes to 47 degrees and 49 minutes east and latitude 35 degrees to 35 degrees and 8 minutes North is located. The study area was 65 points for sampling. The dominant rocks in the region of 10 to 12 samples and the rest of the lithological units that are less extensive number of 8 to 10 rock samples were taken. A total of 7 types of geological unit was selected. Similarly sampling location of all lithological units in section back slope. Using a non-metallic shovel in the middle of 0 to 10 cm from ground level, a total of 65 soil samples were taken. The total amount of heavy metals zinc, copper, nickel and chromium in soil (extractable with nitric acid 5 N) and the total amount of these elements in parent rocks (extractable by mixing 5.0 ml of concentrated nitric acid, 5 ml concentrated Floridric acid and 2 ml of concentrated hydrochloric acid) was determined by atomic absorption spectrometry. Results and Discussion The average concentration of copper in studied soils is 30.3 mg kg-1. Duncan test at 5 level percent showed volcanic basic parent rock (gabbro-basalt) except parent rocks granite porphyry and granite with other unit rocks no significant difference. The average concentration of zinc in studied soils is 79.1 mg kg-1. Duncan test at 5 percent level showed significant difference between porphyritic granite parent rocks with other parent rocks. The average concentration of nickel in studied soils is 81.2 mg kg-1. Result duncan test at 5 percent level showed volcanic basic parent rock (gabbro-basalt) except granite and diorite-gabbro parent rocks with other unit rocks no significant difference. The average concentration of Chromium in studied soils is 76.5 mg kg-1. Duncan test at 5 percent level showed significant difference between spilit-basalt parent rocks with other parent rocks in the study area. The average concentration of total Copper in studied parent materials is 23.5 mg kg-1. Duncan test at 5 percent level showed significant difference existencing between Gabbro diorite and Gabbro-basalt parent rocks with other parent rocks. The average concentration of total Zinc in studied parent materials is 58.2 mg kg-1. Result duncan test at 5 percent level showed volcanic basic parent rock (gabbro-basalt) and Gabbro diorite parent rock except porphyritic granite parent rocks in content of zinc concentration with other unit rocks hasn't significant difference. The average concentration of total Nickel in studied parent materials is 42.4 mg kg-1. Result of Duncan test at 5 percent level showed Gabbro diorite parent rocks except monzodiorite and gabbro-basalt parent rocks in content of total nickel concentration with other unit rocks have significant difference. The average concentration of total Chromium in studied parent materials is 130.1 mg kg-1. Result of Duncan test at 5 percent level showed monzodiorite parent rock except porphyritic granite parent rock in content of total Chromium concentration with other unit rocks hasn't significant difference. Relatively low correlation between copper with zinc (p < 0.05 and r = 0.25) and a relatively high correlation with cobalt (p < 0.01 and r = 0.36), chromium (p > 0.01 and r = 0.34) and nickel (p > 0.01 and r = 0.36) was observed in the study of region soils. Relatively low correlation between zinc with copper (p < 0.05 and r = 0.25) and cobalt (p < 0.05 and r = 0.27) measured in the study of region. High correlation was shown between nickel with chromium (p < 0.01 and r = 0.54) in the study area. Significant and relatively high correlation between copper with zinc (p < 0.05 and r = 0.42), Chromium (p < 0.01 and r = 0.39) and nickel (p < 0.01 and r = 0.46) observed in study of region rocks. Zinc, nickel and copper Contains ionic radius are near to each other and such as iron and manganese can be replaced each other. Zinc significant and relatively high correlation with elements of nickel (p<0.01 and r= 0.5) and chromium (p < 0.01 and r= 0.41) observed in study of region rocks. Significant and high correlation between elements of nickel and chromium (p < 0.01 and r= 0.78) observed that indication of came origin is this elements. Concentration of copper in parent materials and soil developed on them contain significant correlation at one percent level. Between concentration elements of zinc, nickel and Chromium in soil and parent material not existence significant correlation. So parent material may be considered one of the most important factors in controlling the concentration of copper. Given that in the study area sampling be accomplished more than back slope and soil surface, lack of correlation between elements in the soil and parent material may be due to the sediment transfer from another place. Another reason for the discrepancies heavy metals in parent rocks and soils developed on them may be in lack of uniformity parent rock in the region.