Heavy metals (arsenic, cadmium, and mercury) measurement in soil selected parks in Tehran city

The increase in heavy metals(HMs)levels in soil has been mainly attributed to anthropogenic (such as atmospheric deposition, and industrial emissions) and natural (geochemical dissolution of HMs bearing minerals, and geosphere) sources. The goal of this descriptive-analytical research is to investigate of the HMs (arsenic (As), cadmium (Cd), and mercury(Hg)) measurement in topsoil selected parks in Tehran city. In this analytical study, random sampling is used. 22 samples are taken from inside and surrounding topsoil (44 samples) of selected parks in different areas in city of Tehran, from September to October. The samples, about 1 kg of topsoil (0-15 cm depth) are collected in clean self-sealing polyethylene bag according to procedure detailed in national standard methods. We measure the HMs including As, Cd, and Hg by using atomic absorption spectrophotometry. We measure the physicochemical parameters such as pH, electrical conductivity, lime percentage, chemical organic matter, total organic carbon, and soil texture according to procedures detailed in soil and water research institute. We employ the geographical information system (GIS) software package ArcGIS 9.2 for mapping and analyzing the data for the investigation of soil quality in parks. The relationship between the variables is defined by using chi-square test, Pearson correlation and ANOVA methods. The pH, electrical conductivity, lime percentage, chemical organic matter, and total organic carbon range of 22 inside topsoil samples are 7.69-8.09 (7.84-0.18), 0.49-1.26 (0.81-0.24) PRK/FP, 15.27-20 (18.26-1.53) percentage, 6.61-1.54 (4.36-1.79) percentage, and 0.89-3.83 (2.53-1.04) mg/kg, respectively. The pH, electrical conductivity, lime percentage, chemical organic matter, and total organic carbon range of 22 surrounding topsoil samples are 7.67-8.07 (7.82-0.18), 0.51-1.28 (0.83-0.24) PRK/FP 15.29-20.2 (18.28-1.53) percentage, 6.63-1.56 (4.38-1.79) percentage, and 0.91-3.85 (2.55-1.04) mg/kg, respectively. The Cd, Ni, As, Hg, and Pb range of 22 inside topsoil samples are 5.9-6.9 (6.27-0.41), 112.9-104.61 (106.96-3.09) mg/kg, 6.6-48.89 (39.43-16.15) mg/kg, 15.4-71.8 (30.16-21.59) mg/kg, and 51.24-62.1 (56.17-4.71) mg/kg,respectively. The Cd, Ni, As, Hg, and Pb range of 22 surrounding topsoil samples are 5.92-6.92 (6.29±0.41), 112.92-104.63 (106.98±3.09) mg/kg, 6.62-48.91 (39.45±16.15) mg/kg, 15.42-71.82 (30.18±21.59) mg/kg, and 51.26-62.12 (56.19±4.71) mg/kg, respectively.

Keywords:

Atomic absorption spectrophotometry , Heavy metal , Park , Soil , Tehran city