Concentration, Distribution and Comparison of Total and Bioavailable Metals in Top Soils and Plants Accumulation in Zanjan Zinc Industrial Town-Iran

AbstractHeavy metal contamination of metal-mined soils is a widespread problem in parts of Zanjan province. The province located in North West of Iran is highly polluted by heavy metals due to the presence, improper utilization of its mineral resources notably Lead and Zinc, and also the development of a number of related industries. Soils are basically polluted by Pb, Zn and Cd and their concentrations in top soils are very high exceeding European and USEPA standards. The main objective of this study is to evaluate heavy metals concentration and bioavailable fractions of heavy metals and accumulation of such toxic metals in native plants growing naturally on the polluted sites. The information obtained from this study is of great value to obtain bioavailability of the toxic metals and their potential harmful effects for plants, animals and humans

Study on the physical and chemical characteristics of electric arc furnace dust from a steel plant and its reuse as an adsorbent

زمینه و اهداف: گرد و غبار حاصل از کوره های قوس الکتریکی توسط EPA جزء پسماندهای خطرناک طبقه بندی شده است. این مطالعه باهدف سنجش مقدار فلزهای سنگین در گرد و غبار و بررسی حذف آلاینده های آلی با استفاده از این پسماند خطرناک انجام گرفت. مواد و روشها: با هماهنگی مدیریت کارخانه از محل دپوی گرد و غبار کوره قوس الکتریکی کارخانه فولاد اسفراین، نمونه ها برداشت گردید. در آزمایشگاه پس از هضم نمونه ها توسط تیزاب سلطانی، غلظت فلزهای سنگین با استفاده از دستگاه جذب اتمی اندازه گیری شد و برای تعیین مقدار شستشوی فلزهای سنگین از گرد و غبار، از آب مقطر با pH های مختلف1 ، ۳، ۵، ۷ و ۱۱ استفاده شد، ضمن اینکه برای بررسی توانایی گرد و غبار در جذب آلاینده های آلی از دستگاه اسپكتروفتومتری فرابنفش استفاده شد. تمامی مرحله های مطالعه حاضر طبق موازین اخلاقی اجرا گردید. یافته ها: روند تغییر میانگین غلظت فلزهای سنگین در غبار برحسب mg/kg به صورت آهن<منیزیم<روی<منگنز<نیکل<سرب<مس<کادمیوم< کبالت به دست آمد. مطالعه آبشویی این پسماند نشان داد، یون فلزی کبالت در pH های بشترین میزان آبشویی را نسبت به عنصرهای مورد مطالعه دیگر دارد. متیلن بلو، اریوکروم بلاک T، رودامین و دگزامتازون در بین آلاینده های آلی مورد مطالعه ، بشترین مقدار جذب توسط گرد و غبار را داشتند. نتیجه گیری: مطالعه حاضر نشان داد، بازیابی کنسانتره های آهن نسبت به فلزهای دیگر حاصل از این گرد و غبار، مناسب و مقرون به صرفه است و استفاده از گرد و غبار کوره قوس الکتریکی می تواند به عنوان جاذب مناسب، جایگزین جاذب های گران قیمت گردد.Background and Aims: EPA classifies dust from electric arc furnaces as hazardous waste. The purpose of this study was to measure the amount of heavy metals in dust and to investigate the removal of organic pollutants using this hazardous waste.  Materials and Methods: Dust samples were collected from the Esfarayen Steel Plant by coordinating the factory management. Following digestion of samples by Aqua regia solution in the laboratory, the concentration of heavy metals was measured using flame atomic absorption spectroscopy. To determine the rate of heavy metals recovery from the dust, distilled water was used with different pH of 11, 7, 5, 3, and 1. In addition, UV-spectrophotometry was used to investigate the ability of dust to adsorb organic pollutants. All stages of this research were conducted ethically. Results: The average concentration of heavy metals in dust, in mg/kg, was obtained as iron> magnesium> zinc> manganese> nickel> lead> copper> cadmium> cobalt. The leaching study of this waste showed that cobalt metal ion has the highest leaching levels at different pH levels. Methylene Blue, Eriochrome Black T, Rhodamine, and Dexamethasone had the highest amount of adsorption by dust among the organic pollutants studied. Conclusion: The present study showed that the recovery of iron concentrates in comparison with other metals is convenient and cost effective. Furthermore, the electric arc furnace dust can be used as a suitable inexpensive adsorben

A Survey of Heavy Metal Concentrations in the Surface Sediments along the Iranian Coast of the Caspian Sea

Metals discharged into coastal areas of marine environments are likely to be scavenged by particles and removed to the sediments. The sediments, therefore, become large repositories of toxic heavy metals. This research examined the concentrations of heavy metals (Al, Cd, Cu, Pb, Ni, Zn) in the nearshore sediments in the alongshore direction of the Iranian coast of the Caspian Sea. Fourteen samples were collected and granulometric compositions were determined. The consideration of three grain size fractions (0.355 mm, 0.212 mm and 0.075 mm), plus fourteen bulk samples required analyzing 56 samples for the presence of heavy metals. Laboratory analysis of the samples was accomplished using the Cold Acetic Protocol, followed by Inductively Coupled Plasma Optical Emission Spectroscopy. Preparation of the samples involved the utilization of the Cold Acetic Acid Extraction Protocol established by the Great Lakes Institute for Environmental Research (GLIER), Canada. The results provided evidence of large differences in total metal concentrations in the sediment samples from the fourteen sites. Box and Whisker plots demonstrated that metal concentrations were not homogeneously distributed, and that there were large spatial variations in the median concentrations of heavy metals at each sample site. The statistical technique of discriminant analysis revealed that the six heavy metals had distinct and statistically significant concentrations at various locations along the coast. Concentrations reflected metal loadings from anthropogenic sources located at and in the vicinity of the sampling sites