تاثیر کاربری اراضی و ژئومورفولوژی بر غلظت فلزات سنگین در بخشی از حوضه آبخیز سد زاینده رود

مطالعات کمی در مورد بررسی تاثیر کاربری اراضی و ژئومورفولوژی بر روی غلظت فلزات سنگین که فاقد فعالیت‌های صنعتی می‌باشد، انجام شده است. این مطالعه به بررسی کاربری اراضی و ژئومورفولوژی بر برخی از ویژگی‌های خاک، غلظت فلزات سنگین و پذیرفتاری مغناطیسی در بخشی از حوضه آبخیز سد زاینده رود واقع در استان اصفهان انجام شده است. در این پژوهش 100 نمونه خاک به‌صورت تصادفی-طبقه بندی شده از عمق 0 تا 20 سانتی‌متر برداشت و غلظت فلزات سنگین، پذیرفتاری مغناطیسی و و برخی ویژگی های فیزیکی و شیمیایی خاک اندازه‌گیری شد. نتایج نشان داد که بین کربنات کلسیم، هدایت الکتریکی، پذیرفتاری مغناطیسی با فلزات سنگین در کاربری‌ها و لندفرم‌های ژئومورفولوژی همبستگی وجود داشت؛ اما بین کربن آلی و فلزات سنگین همبستگی چندانی دیده نمی‌شد که می‌توان به فقر مواد آلی در خاک های منطقه ناشی از فرسایش خاک، تغییر کاربری اراضی، کاربرد محدود مواد آلی در خاک، و شرایط اقلیمی منطقه نسبت داد. نتایج نشان داد که غلظت فلزات سنگین و پذیررفتاری مغناطیسی بیشتر تحت تاثیرسطوح ژئومورفولوژی قرار گرفته و کمترتحت تاثیر کاربری اراضیقرار گرفته است.

impacts of land use and geomorphology on some heavy metal concentrations in a part of zayandehroud dam watershed

introduction with the rapid development of industry and urbanization, soil pollution with heavy metals as a result of ecosystem destruction has attracted global attention. pollutants are considered environmental threats and among pollutants, heavy metals are known for their non-degradability and physiological effects on living organisms even at low concentrations. the close correlation of magnetic properties and heavy metals shows that magnetic measurement is an efficient and cheap tool to detect heavy metal contamination in soils affected by heavy industries and traffic pollution. magnetic minerals in soil may be inherited from parent rocks (lithogenic origin), pedogenesis (pedogenic origin), or may result from human activities (secondary ferromagnetic materials). the concentration of metals can be influenced by geomorphology and various soil properties such as organic carbon, electrical conductivity. land use directly or indirectly affects the geochemical behaviors of heavy metals through regulating soil properties. the main objectives of this study were to investigate the effect of land use change on magnetic receptivity and the concentration of some heavy metals including zinc, copper, iron, nickel, chromium, cobalt and manganese in the 20 cm soil surface layers, and to explore spatial distribution of magnetic receptivity and heavy metals under different types of land use and geomorphological units in the studied area.materials and methods the present research was conducted in isfahan province in the center of iran with an area of 227 km2. this area has an average temperature of 9.8 oc and an average annual rainfall of 324 mm and an altitude of 2380 meters a.s.l. based on kopen's classification, the climate was classified as semi-arid with cold winters. geologically, it belongs to the sanandaj-sirjan zone, the dominant rocks of the area include limestone, shale limestone, slate and quaternary sediments. the most important land uses in the region included pasture, rainfed and irrigated agriculture, and in terms of geomorphology, the region comprised river plains and pediments. soil sampling was done by stratified random method. a total of 100 samples were collected from the surface layer (0-20 cm depth) in the summer of 2021. magnetic susceptibility was measured at high and low frequencies using bartington ms2 dual frequency sensor. the concentration of heavy metals including iron, zinc, manganese, nickel, copper, chromium and cobalt were measured by atomic absorption spectroscopy. ph, organic carbon, calcium carbonate, electrical conductivity were measured in all samples. spearman's correlation coefficient was used to check the correlation between different parameters. analysis of variance was applied to evaluate the effects of geomorphology and land use on heavy metals and magnetic susceptibility. spatial analysis was performed for heavy metals and magnetic susceptibility, and the maps were prepared in arcgis v.10.7 software.