Assessment of Ordinary Kriging and Inverse Distance Weighting Methods for Modeling Chromium and Cadmium Soil Pollution in E-Waste Sites in Douala, Cameroon.
Romaric Emmanuel Ouabo, Abimbola Y Sangodoyin, Mary B Ogundiran
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引用次数: 19
Abstract
Background: Several studies have demonstrated that chromium (Cr) and cadmium (Cd) have adverse impacts on the environment and human health. These elements are present in electronic waste (e-waste) recycling sites. Several interpolation methods have been used to evaluate geographical impacts on humans and the environment.
Objectives: The aim of the present paper is to compare the accuracy of inverse distance weighting (IDW) and ordinary kriging (OK) in topsoil analysis of e-waste recycling sites in Douala, Cameroon.
Methods: Selecting the proper spatial interpolation method is crucial for carrying out surface analysis. Ordinary kriging and IDW are interpolation methods used for spatial analysis and surface mapping. Two sets of samples were used and compared. The performances of interpolation methods were evaluated and compared using cross-validation.
Results: The results showed that the OK method performed better than IDW prediction for the spatial distribution of Cr, but the two interpolation methods had the same result for Cd (in the first set of samples). Results from Kolmogorov-Smirnov and Shapiro-Wilk tests showed that the data were normally distributed in the study area. The p value (0.302 and 0.773) was greater than 0.05 for Cr and for Cd (0.267 and 0.712). In the second set of samples, the OK method results (for Cd and Cr) were greatly diminished and the concentrations dropped, looking more like an average on the maps. However, the IDW interpolation gave a better representation of the concentration of Cd and Cr on the maps of the study area. For the second set of samples, OK and IDW for Cd and Cr had more similar results, especially in terms of root mean square error (RMSE).
Conclusions: Many parameters were better identified from the RMSE statistic obtained from cross-validation after exhaustive testing. Inverse distance weighting appeared more adequate in limited urban areas.
Competing interests: The authors declare no competing financial interests.
期刊介绍：
The Journal of Health and Pollution (JH&P) was initiated with funding from the European Union and World Bank and continues to be a Platinum Open Access Journal. There are no publication or viewing charges. That is, there are no charges to readers or authors. Upon peer-review and acceptance, all articles are made available online. The high-ranking editorial board is comprised of active members who participate in JH&P submissions and editorial policies. The Journal of Health and Pollution welcomes manuscripts based on original research as well as findings from re-interpretation and examination of existing data. JH&P focuses on point source pollution, related health impacts, environmental control and remediation technology. JH&P also has an interest in ambient and indoor pollution. Pollutants of particular interest include heavy metals, pesticides, radionuclides, dioxins, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), air particulates (PM10 and PM2.5), and other severe and persistent toxins. JH&P emphasizes work relating directly to low and middle-income countries, however relevant work relating to high-income countries will be considered on a case-by-case basis.
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