Studies on the Accumulation and Elimination of Mercury in the Crucian Carp (Carassius carassius)

Abstract

This paper deals with the accumulation and elimination of mercury in tissues of Crucian carp (Carassius carassius). Four different concentrations of mercury are applied in this study, they are 500 ppb, 50 ppb, 20 ppb and 2 ppb. The former two are applied for short-term study, and the latter two are applied for long-term study. Our results indicate that the gill and viscera especially the kidney, can accumulate more mercury than flesh. And the lower Hg concentration is in the ambient water, the higher concentration factor is in the fish body. After 12 days in short-term study, the accumulation amount of mercury in each tissue in decreasing order is as follows: kidney, intestine, liver, gill and flesh. After 20 days in long-term study, the results are same as that of short-term study. But after 50 days in long-term study, the order has changed to the following sequence: kidney, liver, intestine, gill and flesh. These facts suggest that the mercury accumulated in the intestine may have migrated to the liver. The mercury accumulated in gill, intestine and flesh decreased greatly after transferring the fish to clean water for 10 days. Our results also show that the less original mercury concentration is in the ambient water, the higher percentage it is eliminated from the fish body. On the contrary, the mercury amount in the kidney of fish, which were exposed to 20 ppb of mercury, increases greatly after transferring to clean water for 10 days. The mercury accumulated in the viscera, gill and flesh may have been eliminated or transported into other tissues.本篇論文討論水中溶解汞對於鯽魚(Carassius carassius)體內之蓄積與排出之情形，汞之濃度分別為500ppb、50ppb、20ppb及2ppb，前二者做為短期實驗，後二者做為長期實驗，，其結果顯示內臟較肌肉容易蓄積，尤以腎之蓄積量最大。另外也得知水中汞之濃度愈大，在魚體內汞之蓄積量也愈大，但相反地，水中汞之濃度愈大，魚體內汞之濃縮因素(concentration factor)反而愈小。短期實驗組經過12天後，蓄積量之大小依次為腎、腸、肝、鰓、肉。長期實驗組在第20天時，其體內蓄積量之順序也和短期實驗組相同，但是到了40～50天則變成腎、肝、腸、鰓、肉，蓄積在腸之汞有向肝移動之可能，長期實驗組在換成清水飼育10天後測得之結果顯示蓄積在鰓、腸及肉之汞量均減少了，而且原來水中濃度愈低，其減少的量也愈多，2ppb之腎及20ppb之肝，汞蓄積量也有減少，但20ppb之腎，其汞蓄積量反而有明顯增加，蓄積在內臟及肌肉之汞於清水中可能有排出或轉移之情形。