Identification of Pollution Source of Cadmium in Soil. Application of Material Flow Analysis and A Case Study in Taiwan (11 pp) |
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Authors: | I-Cheng Chang Teng-Yuan Hsiao Yue-Hwa Yu Hwong-Wen Ma |
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Institution: | (1) I-Cheng CHANG, Ph.D. Assistant Professor Department of Health and Environmental Engineering Lan Yang Institute of Technology No. 79 Fushing Rd. Toucheng Jen, Ilan 261 TAIWAN, , ,;(2) Teng-Yuan Hsiao, Ph.D. Assistant Professor Chairman of Department of Tourism Industry Jin-Wen Institute of Technology No. 99, An-Chung Rd. Hsin-Tien, Taipei County, TAIWAN 231, , ,;(3) Yue-Hwa Yu National Taiwan University Graduate Institute of Environmental Engineering 71 Chou-San Rd. Taipei 106 Taiwan, , ,;(4) Hwong-Wen Ma National Taiwan University Graduate Institute of Environmental Engineering 71 Chou-San Rd. Taipei 106 Taiwan, , , |
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Abstract: | Background Since the 1970s, at least 200 hectares (ha) of farmland has been polluted by the heavy metal cadmium (Cd).Consequently, the
Cd pollution has led to contaminate the rice production and caused acute social panic. According to the recent investigation
results performed by the Taiwan Environmental Protection Administration (TEPA), it is indicated that most of the Cd pollution
incidents in Taiwan resulted from the wastewater discharge of stearate Cd factories. To prevent the Cd pollution incidents
from spreading, the TEPA has either forced these factories to close down or assisted them in improving their production processes
since the 1980s. Unfortunately, accidental incidents of Cd pollution still emerge in an endless stream, despite the strict
governmental controls placed on these questionable factories. Whether this pollution has resulted from undetected or hidden
pollution sources stemming from two decades ago or comes from some new source, will be an outstanding issue. Therefore, this
study attempts to identify the pollution sources of Cd in soil in Taiwan as well as to find the solution to the above-mentioned,
outstanding issue by way of a methodology termed Material Flow Analysis (MFA).
Method logy. The MFA has proved to be a useful tool on providing quantitative information of the flow of substances through an economic
to an environmental system. Based upon the supply-and-demand theory of MFA, researchers have successfully conducted an overview
of the use of materials in many industries, the construction industry being one of these. Therefore, this study tries to establish
a set of analytical processes by way of MFA for identifying the pollution source of Cd in soil in Taiwan. In addition, the
spirit of Life Cycle Analysis (LCA) technique was also employed to identify the materials, and products should be ignored
as a crucial pollution source in this study.
Results and Discussion According to the MFA methodology applied in this study and on the basis of related studies performed by Taiwanese governmental
authorities, we arrive at the following analysis results: (1) the total amount of Cd from the economic perspective of material
and product flow was approximately 441.2 tons; (2) the wastewater directly discharged into irrigation water can be concluded
to be the major pollution route of Cd in farmland soil in Taiwan; (3) material plastic stabilizer (cadmium oxide, CdO), Zn-Pd
compounds and Cu compounds should be the crucial pollution sources to contaminate environment through the route of wastewater
in Cd flow analysis; (4) the crucial pollution sources to contaminate environment through the route of wastewater in Cd flow
analysis were five factories, Coin, Jili, Taiwan Dye, Guangzheng and Mingguan, and they were all categorized as stearate Cd
industries; (5) the typical source of the Cd pollution in soil in Changhua County through the pollution route of wastewater
should be the metal surfacing process industries.
Conclusions This study proved that MFA can be a good tool for identifying Cd flow as well as for recognizing the crux of the problem
concerning incidents of Cd pollution. This study led to the conclusion that the causal relationship between farmland pollution
caused by Cd and stearate Cd factories in Taiwan seemed quite close by way of MFA methodology. In addition, this study also
found that the wastewater discharged from a single metal surfacing process factory will not cause remarkable farmland pollution.
However, the wastewater simultaneously discharged from a group of pollution factories can result in a significant pollution
incident.
Recommendations and Outlook This case study is only a small contribution to the understanding of the toxic material flow related to Cd in the environment.
This study recommends that Taiwanese governmental authorities should not deal with problems on an ad hoc basis, but should
instead deal with Cd pollution problems overall employing control measures. Finally, the more accurate information or data
we can collect, the more reliable results we can identify. Therefore, the quality and quantity of related data used in this
MFA model should be closely scrutinized in order to ensure the most correct and comprehensive investigation on the toxic material
flow. |
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Keywords: | cadmium (Cd) metal surfacing process heavy metal Material Flow Analysis (MFA) farmland Cd pollution Cd pollution in soil stearate Cd factory |
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