Spatial distribution of heavy metal content in soils around an industrial area in Southern Turkey
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ORIGINAL PAPER
Spatial distribution of heavy metal content in soils around an industrial area in Southern Turkey Necat Ağca
Received: 3 August 2013 / Accepted: 11 December 2013 # Saudi Society for Geosciences 2014
Abstract The purpose of this study is to investigate heavy metal contents and to determine their spatial distribution in soils around industrial areas. A total of 102 soil samples were collected by a variable-distance grid sampling technique at depths 0–5 and 5–20 cm from 51 locations. Samples were analyzed for pH, electrical conductivity (EC), organic matter (OM), particle size distribution (sand, silt, and clay), and available heavy metal (Cd, Cr, Co, Cu, Fe, Mn, Ni, Pb, and Zn) concentrations. Descriptive statistics, correlation, and principal component analysis (PCA) were applied to the transformed data. Maps of the spatial distribution of heavy metal concentrations in the research area were generated using kriging interpolation of data for surface and subsurface soils. Mean pH, EC, and OM varied between 7.93–7.98, 293.7–275.7 μS cm−1 and 5.83–3.61 %, respectively. Average values of the heavy metals at both depth ranges showed the following order: Zn>Fe>Mn>Ni=Pb> Cu>Co>Cr>Cd. PCA analysis showed that Cd, Cu, Pb, and Zn may have a similar source. Contents of these metals were the highest around the industrial area and roads. Fe was high in the industrial and forest areas, whereas Mn and Ni contents were high in agricultural and forest lands. The spatial distribution of Co appears controlled by both natural and anthropogenic factors, and that of Cr by only natural factors. Keywords Heavy metals . Geostatistics . Kriging . Principal component analysis (PCA)
Introduction Soil contamination by heavy metals is one of the major permanent environmental problems in ecosystems (Kabata-Pendias N. Ağca (*) Department of Soil Science and Plant Nutrition, Faculty of Agriculture, Mustafa Kemal University, Antakya, Hatay, Turkey e-mail: [email protected]
and Mukherjee 2007). Soil metals usually originate from soil parent materials through pedogenic processes. However, heavy metal accumulation in soils has been a subject of globally growing concern, since heavy metals do not decay with time and may become toxic to microbial and plant biota when exceeding threshold values. Heavy metals are generally present in soils in cationic forms and may therefore show low availability even at high total concentrations, since they interact with the soil matrix. However, they can become mobile as a result of changing environmental conditions or by saturation exceeding the buffering capacity of a soil (Facchinelli et al. 2001). Metals can enter the environment as a result of both natural and anthropogenic activities, so they are found ubiquitously in both polluted and unpolluted soils. Natural sources that include processes of pedogenesis lead to mineral breakdown and translocation of the products, as well as accessions from dust storms, volcanic eruptions, and forest fires (Kawy and Belal 2012). In the urban environment, soils
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