Acute toxicological effects of excessive Cu and Zn-containing in pig manure on earthworm
高铜、高锌猪粪对蚯蚓的急性毒性效应研究

Cu and Zn are popularly used as additives in animal feed in China,which could result in their excessive accumulation in manure to a toxic level,and thus,possibly threaten the environment when the manure is applied to farmland.In this paper,the acute and sub-acute lethal effects of pig manure with excessive Cu and Zn on earthworm were studied,and the results indicated that the concentration of Cu and Zn in pig manure had a significantly positive correlation with the mortality of earthworm,while a significantly negative correlation with earthworm growth rate.The individuals of earthworm had different tolerance to excessive Cu and Zn,with the threshold values causing death being 250 mgkg~(-1) and 400 mgkg~(-1)for Cu and Zn,respectively.The LD_(50) was 646.68 mgkg~(-1) for Cu,and 947.38 mgkg~(-1) for Zn.A strong synergistic effect was observed under the combined pollution of 250 mgkg~(-1) for Cu and 500 mgkg~(-1) for Zn,whereas antagonistic effect happened when 750 mgkg~(-1) for Cu was supplied,suggesting that the joint toxic effects of Cu and Zn on earthworm were closely correlated to their concentrations in pig manure.