以土壤特性評估蔬菜鎘含量

Abstract

本研究依據前人研究提出之蔬菜鎘含量預測模式，整合雲林縣農地土壤特性參數等相關資料，推估雲林縣農地種植不同蔬菜的鎘含量，並配合國人蔬菜消耗量檢視國人食用這些蔬菜的安全性；亦對蔬菜鎘含量預測模式的係數進行敏感度分析，探討影響預測模式中蔬菜鎘含量的主要因子。研究結果發現，平均鎘濃度推估最高的5種蔬菜為福壽/翠花萵苣、菠菜、尖葉萵苣、圓葉萵苣及莧菜。由於蔬菜的重金屬鎘限量標準規範依不同種類而異，歸納出比較容易超標的蔬菜種類是半結球類、瓜菜及果菜類及大蒜。因為國人對葉菜類需求較其他類別蔬菜高，葉菜類之中的小葉菜類蔬菜鎘濃度整體來說比較高，所以葉菜類攝食成為鎘進入人體的主要途徑。最後經由敏感度分析得知，蔬菜鎘含量預測模式中γ絕對值大的蔬菜，在土壤CEC低時會致使蔬菜鎘含量顯著增加；δ絕對值大的蔬菜，種在土壤pH值低的地方，其鎘含量會比種在高土壤鎘濃度情況下為高。根據以上結果，建議有關單位可以參考本研究結果選擇蔬菜適栽地點，並且留意小葉菜類蔬菜的鎘含量，以減少產出含鎘超標蔬菜。

Based on the predictive model for Cd content levels in vegetables proposed by Taiwan Agricultural Research Institute in a former research, this study integrated soil characteristics parameters needed for the model to predict Cd content of 31 vegetables cultured in Yunlin County. The vegetable consumption is one of the major pathways of Cd uptake in Taiwan residents. If we can understand the Cd content in vegetables, then we can manage health risk better. The aim of this study is to estimate Cd content level in various vegetables to be planted in Yunlin County, which is the most important production area in Taiwan. This study further conducted sensitivity analysis of coefficients in the predictive model for Cd content levels in vegetable to find out the main factors affecting Cd content in vegetables. The model predicted that there could be 5 vegetables with the highest Cd content level, including iceberg lettuce, spinach, two kinds of leaf lettuce and amaranth. This study also found some classes of vegetables that could be easier to exceed their regulatary standards for Cd content, including head vegetables, melon vegetables and fruit vegetables and garlic. In addition, this study predicted that leafy vegetables could have higher Cd content and may become a main pathway of Cd uptake because Taiwan residents currently eat more leafy vegetables than other vegetables. Finally, the model sensitivity analysis showed that vegetables with higher γ would gain more Cd content when planted in the soil with lower CEC; vegetables with higher δ would gain more Cd content when planted in the soil with lower pH than in the soil with high level of Cd content. This study suggested agricultural authorities can use the results of this study to guide farmers to choose planting suitable vegetables in right locations, to pay attention to cadmium content in leafly vegetables, and to reduce the production of vegetables with high Cd content.