重金属对蚯蚓的毒性毒理研究

通过室内模拟实验以及对株洲市重金属污染区农田土壤中采样，进行了重金属对蚯蚓的毒性毒理研究．毒性实验表明，各重金属元素４８ｈ的ＬＤ５０分别为：Ｃｄ１０００ｍｇ／ｋｇ，Ｐｂ８１２ｍｇ／ｋｇ，Ｃｕ６３３ｍｇ／ｋｇ，Ｈｇ３０４ｍｇ／ｋｇ，Ｚｎ５２８ｍｇ／ｋｇ，Ｃｒ４２８ｍｇ／ｋｇ．对蚯蚓毒理研究证明，重金属对蚯蚓酯酶同工酶有抑活作用，而重金属对蚯蚓过氧化物酶同工酶有激活作用．在光镜下观察，可见重金属污染可引起蚯蚓的体表溃疡及产生肿瘤，可使胃肠道粘膜层出血、背血管肿胀，同时可引起胃肠道粘膜上皮细胞产生萎缩或溃疡灶．蚯蚓特有的黄色细胞团污染程度不同而显示出消长规律．在电镜下可见到在重污染区的蚯蚓胃肠道粘膜上皮细胞中的ｒＥＲ肿胀、高尔基体膨大，线粒体嵴消失，甚至空泡化或解体．另可见细胞核膜间隙肿胀、断裂、核质外溢，胞质自溶．蚯蚓以上病变的大小是随土壤重金属污染区的污染级别而定；各病理变化指标均能定性地反映土壤重金属污染状况．

STUDIES ON TOXICITY AND TOXICOLOGY OF HEAVYMETALS TO EARTHWORMS IN POLLUTED SOILS

The results from the tests of heavy metal toxicity to the earthworms collected from the Polluted soils indicated that the various heavy metals LD50 (mg/kg)after treated for 48h were cd 1000 mg/kg,Pb 707mg/kg,Cu 633 mg/kg,Hg 304 mg/kg,Zn 566 mg/kg,and Cr 450 mg/kg respectively.The toxicological analyses indicated that the activity of esterase isozymes of the earthworms was inhibited by the heavy metals,but their catalase isozymes were activated. Under light microscope,it could be observed that the heavy metal pollution might cause ulcer or tumour on the body surface of earthworms,blood letting and epithelial cells shrinking or atrophying on their intestinal mucosa and dorsal blood vessels swelling.Under electron microscope,it could be seen that the rER,Golgi cisternae and mitochondrion swelling in the mucosa cells of the earthworms from the seriously polluted soils,and even the vesiculation appeared or lysis took place and cristae disappered.It could also be seen that in the body of earthworm the perinuclear cisterna swelled)nuclear envelope broke,nucleoplasm flowed out and complasm autolysed. These pathologies changed with different degrees of heavy metal pollution.Each of pethological indiCators could qualitatively responds to heavymetal pollution in soils.