Environment Parameters Affecting Heavy Metal Concentration in Sand Collected from Children Playground in Seoul Metropolitan Area

Abstract

The concentrations of heavy metals such as cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), zinc (Zn), nickel (Ni), and arsenic (As) in sand samples collected from selected children's playground and their correlation with environmental parameters, such as concentration of particulate matter in the atmosphere (<TEX>$PM_{10}$</TEX>), apartment age (> 5 years), clay and organic matter contents in sand samples, were analyzed. The average heavy metal concentration in samples was 0.040 mg <TEX>$kg^{-1}$</TEX> for Cd, 0.200 mg <TEX>$kg^{-1}$</TEX> for Cr, 1.75 mg <TEX>$kg^{-1}$</TEX> for Cu, 15.1 mg <TEX>$kg^{-1}$</TEX> for Ni, 3.42 mg <TEX>$kg^{-1}$</TEX> for Pb, 66.7 mg <TEX>$kg^{-1}$</TEX> for Zn and 0.750 mg <TEX>$kg^{-1}$</TEX> for As, all of which were below the environmental regulatory level established by Korea Ministry of Environment. However, in the consideration of direct and oral exposure by children to playground sand, the risk of the concentration range in the samples might be greatly enhanced. Heavy metal concentration in samples collected from high <TEX>$PM_{10}$</TEX> (> <TEX>$70{\mu}gm^{-3}$</TEX>) area was slightly greater than in samples from low <TEX>$PM_{10}$</TEX> (< <TEX>$70{\mu}gm^{-3}$</TEX>), indicating the contribution of particulate matter in air phase to heavy metal concentration in playground sand samples. The concentrations of both Cd and Pb were the highest in apartments older than 21 years (0.050 mg <TEX>$kg^{-1}$</TEX> and 5.28 mg <TEX>$kg^{-1}$</TEX> for Cd and Pb respectively) and showed positive correlation with apartment age (p<0.01 and p<0.001 for Cd and Pb, respectively). Clay content in playground sands ranged 3.8~11.2% and was positively correlated with heavy metal concentration. Organic matter content was negligible (mostly < 0.1%) and showed poor correlation with heavy metal concentration. In conclusion, concentration of heavy metals in playground sand was found to be predominantly influenced by the apartment age and clay content in sand samples and supplemented by dust deposition of particulate matter (<TEX>$PM_{10}$</TEX>) from atmosphere.