en Environmental Health, Sciences, and Engineering Environmental Health, Sciences, and Engineering پژوهشي Original Article <span style="font-size:14px;"><span style="font-family:Times New Roman;"><span style="line-height:normal"><b><span style="background:white"><span style="color:#1d2228">Background</span></span>: </b>This study investigated the effect of inorganic and organic sources of iron on Pb availability in soil.</span><br> <span style="line-height:normal"><b><span style="background:white"><span style="color:black">Methods</span></span>:</b> The treatments involved applying organic and inorganic Fe sources at the rate of 0, 30, and 60 kg/ha pure Fe from different sources in the Pb-polluted soil treated with municipal sewage sludge biochar (MSSB). Corn was chosen as the tested plant in this experiment. The plants were collected after 90 days, and the Pb concentration in the soil and plants was determined using atomic absorption spectroscopy (AAS). Further, the plant enzyme activity was determined.</span><br> <span style="line-height:normal"><b>Results: </b>Soil application of ethylenediamine Di-2-Hydroxyphenyl Acetate Ferric (Fe-EDDHA) had the greatest efficiency in reducing the soil and plant concentration. Using 30 kg Fe/ha from Fe-EDDHA relative to iron slag and FeSo₄ source significantly decreased the plant Pb concentration by 11.6 and 9.8%, respectively. For ascorbate peroxidase (APX) and peroxidases&nbsp;(POX) enzyme activity, it was decreased by 17.2 and 15.4%, respectively.</span><br> <span style="line-height:normal"><b>Conclusion: </b>Considering the results of this research, using inorganic and organic Fe sources in soil treated with MSSB had a substantial impact in reducing the soil and plant Pb concentration which is an advantage of environmental studies.</span></span></span> Iron source, Biochar, Heavy metal, Corn, Municipal Sewage Sludge, 106 111 http://jhehp.zums.ac.ir/browse.php?a_code=A-10-230-10&slc_lang=en&sid=1 Masoumeh Abedi M@yahoo.com 100319475328460012912 0000000275824798 No Department of Environment, Arak Branch, Islamic Azad University, Arak, Iran. Amir Hossein Baghaie am.baghaie@iau.ac.ir 100319475328460012913 0000000289361202 Yes Department of Soil-Science, Arak Branch, Islamic Azad University, Arak, Iran; Department of Development and Agricultural Economics, Food Security Research Institute, Arak Branch, Islamic Azad University, Arak, Iran. Hamid Toranjzar H@yahoo.com 100319475328460012914 000000027547904X No Department of Environment, Arak Branch, Islamic Azad University, Arak, Iran.