土壤中鎘含量與水稻植物體不同部位鎘濃度變化之研究

Cadmium Content in the Soil and Its Uptake and Distribution in the Different Parts of Rice Plants

謝慶芳(C. F. Hsieh)

《臺中區農業改良場研究彙報》 29期 (1990/12) Pp. 11-27

https://doi.org/10.6956/BTDAIS.199012.0011

摘要

本試驗是在彰化縣花壇鄉白沙村一塊遭受鎘污染之農田舉行。由於該地區之鍍鎘工廠已經全部被命令停工，不再有鍍鎘廢水流入灌水溝，雖然仍有其他鍍鋅、鎳、銘、銅等廢水偶而出現在溝中，但已經很少有機會流入農田為害，因為農民都已改用地下水灌溉。試驗結果發現，鎘污染田中鎘的水平分布以進水口的5.8 ppm最高，隨著離開進水口距離之增加而濃度也逐漸降低至約1 ppm左右；鎘的垂直分布則以表土0～15 cm層最高，但有些採樣點15～30 cm層之鎘濃度也與表土相似，表示田區某些部位的鎘也有向下移動現象。水稻植物體之含鎘量以根頭部最高，約11～38 ppm；其次為莖部3～17 ppm；葉片居第三，1～7.5 ppm；糙米居第四，0.5～2 ppm；穀殼最低，約0.2～1.2 ppm；糙米之含鎘量雖有隨著土壤含鎘量減少而逐漸降低之現象，但其降勢很慢，土壤含鎘量4～5 ppm處之糙米含鎘量約1～2 ppm，而土壤之含鎘量1～2 pprn處之糙米含鎘量約0.5～1 pprn，仍然超過0.5 ppm之我國現行糙米鎘污染標準；但土壤之含鎘量4～5 ppm對水稻之生長和產量仍然沒有明顯的影響。

關鍵字

鎘污染 ； 土壤 ； 植物體 ； 糙米

並列摘要

This experiment was conducted in a cadmium-polluted paddy soil at Huatan in Changhua Hsien. As all of the cadmium-gilting factories in this area has been forced to close, there is no more cadmium-polluted water flowing into the experiment plot now. However some other polluted water with zinc, nickel, chromium, and copper etc. occasionally appeared in the irrigation ditch, but it had very rare chance for these polluted water to get into the paddy field again, because all of the farmers in this area are now adopting deep-well water to irrigate their paddy fields.It was found in the experiment that the soil at the inlet area of irrigation water was the most seriously polluted, showing 5.8ppm cadmium in the top soil, but it gradually decreased to about 1 ppm with the increase of distance from inlet to the position of 30 meters. As to the vertical distribution of cadmium, the highest cadmium was usually found in the top soil (0~15 cm layer), and it significantly decreased with the increase of depth, however in some spots of the plot, the cadmium in 15~30 cm layer was similar to those in the 0~15 cm layer, suggesting that in some areas of the plot, the cadmium had moved down to the subsoil.The analysis for cadmium content in rice plants showed that root and stubble with 11~38 ppm was the highest; 3~17 ppm in the stem next to it; 1~7.5 ppm in the leaves was the third; 0.5~2 ppm in brown rice was the fourth; and 0.2~1.2 ppm in rice hull was the lowest. Although cadmium in brown rice generally decreased with the decrease of cadmium content in the soil, this decreasing tendency was not sharp enough; in the spot with 4~5 ppm cadmium in the soil, the cadmium content in brown rice was 1~2 ppm; and in the spot with 1~2 ppm cadmium in the soil, the cadmium content in brown rice was 0.5~1 ppm that were still higher than the 0.5 ppm cadmium critical level stipulated by the Environmental Protection Bureau, however it was apparent that 4~5 ppm cadmium in the soil was still unharmful to the growth and yield of rice plants.

並列關鍵字

Cadmium pollution ； soil ； plant parts ； brown rice