Agricultural Land Suitability Mapping for Rice Cultivation in Severely Heavy Metal-Contaminated Land: Case Study of Mae Tao in Thailand
2021
Srisawat, Lamai | Satapanajaru, Tunlawit | Anurakpongsatorn, Patana | Jarusutthirak, Chalor | Yoo-iam, Maneekarn
An agricultural land suitability map was developed for rice (Oryza sativa L.) cultivation of land severely contaminated with heavy metals at Mae Tao, Thailand, as a representative area from which more than 300 soil samples and 100 rice grain samples were collected. The average concentrations for As, Cd, Pb, and Zn in the soil were 20.99, 2.66, 19.92, and 115.62 mg/kg, respectively The geo accumulation index (Igeo) values for As, Cd, Pb, and Zn indicated that this area was highly contaminated with Cd. Land suitability maps were developed for three scenarios: I—following conventional factors in the Storie index; II—adding factor D (heavy metal contamination) with the same weighting for four heavy metals; and III—with factor D focusing on As contamination. The results revealed that adding factor D in the Storie index decreased the suitable area for rice cultivation. Taking into account heavy metal contamination of the soil in land suitability mapping, it reduced the areas of highly suited, suited, and marginally suited by 15%. However, the concentration of heavy metals in rice grain in highly suited and suited land was lower than the Codex standard for food safety and quality. This was confirmed by the hazard index (HI) for rice grain planted in scenarios including factor D (HI < 1). Our research should lead to agricultural land management to protect human health from the danger of consuming rice contaminated with heavy metals.
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