Geostatistical Analysis of Soil Heavy Metal Content in Taiwan
| Autor: | Guey-Shin Shyu, 徐貴新 |
|---|---|
| Rok vydání: | 1999 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 87 Geographic distribution of heavy metal content in soil reflects an important meaning for agriculture, water quality, and health. Therefore, the EPA of Taiwan has made a systematic study and investigation on soil contents of As, Cd, Cr, Cu, Pb, Hg, Ni and Zn in various regions of Taiwan. If the investigation results can be analyzed by appropriate scientific methodology, we then can come to an understanding of the pollution characteristics and spatial distribution and to appreciate more the value of this study. In the study, methods including factor analysis, ordinary kriging (OK), indicator kriging (IK) and multiple-variable indicator kriging (MVIK) were employed to analyze various sets of data in order to identify the pollution patterns and to delineate the range of contaminated sites. Results are shown using the tool of GIS. In the first section of this study, factor analysis method was used to study the major pattern of pollution in Taiwan. Three major factors from eight variable originally were found. Meanwhile, the cause of pollution was discussed. According to the survey results, the agricultural areas in Chang-Hua and Tai-Chung are most severely pollution. A possible reason could be that there were many plating factories in that area, and wastewater was discharge to rivers without appropriate treatment. Factor analysis method was employed to analyze the soil heavy metals content data of Chang-Hua county. Four common factors were extracted followed by ordinary kriging to estimate the spatial distribution of factor scores. Indicator kriging and multiple-variable indicator kriging were used to predict the probability distribution of heavy metal content excess the maximum allowable level (MAL). In the last section of this study, maps illustrating the geographic distribution of heavy metal in topsoil (0-15cm) horizons of Taiwan were developed using geostatistics and geographic information systems (GIS). We used variography, linear regression, and sensitivity analysis to characterize the spatial variability of heavy metal based on data from EPA. We used geostatistical interpolation, i.e., ordinar kriging, to estimate and map the total soil heavy metal content throughout Taiwan. The results showed that soils southwest of Taiwan tended to contain higher levels of As than average. Soils around Miao-li, Chang-Hua Tai-Chung, Kao-Hsiung Ping-Tung areas tended to contain higher levels of Hg than average. The resultant map depicted soils western of Taiwan having different characteristic. High estimate standard deviations occurred in the central mountain where data were sparse. The map will be useful in future research to determine the geographic distribution of heavy metal soils content, regional pattern of plant, genesis and topsoil geology, and in considering the consequences of land disposal of heavy-metal-laden wastes. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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