Acute and Chronic Toxicity of Selected Cadmium Salts on Earthworm Eisenia andrei under Tropical Conditions

Abstract

Attached

A grochem icals and other hazardous chem icals are w ell know n threats to healthy soil ecosystem s. Fertilizers containing cadm ium as an im purity are being added extensively to agricultural soils in Sri Lanka. These im purities m ay have hazardous impacts on soil ecosystem s. T herefore toxicity o f Cadm ium Chloride (C dC k) and C adm ium Sulphate (CdSO-O on survival, grow th and reproduction o f the earthw orm Eisenia andrei w ere investigated under tropical conditions. T he standard earthw orm toxicity tests w ere perform ed according to the guidelines developed b y ISO (International O rganization for Standardization) and OECD (O rganization fo r Econom ic Co-Operation and D evelopm ent). Field collected natural soils w ere used as the test substrates. T he endpoints m easured w ere survival, growth and reproduction together w ith behavioral effects. Coiling, secretion Of m ucus and hypersensitivity w ere noted as com m on behavioral effects, w hich w as observed in the highest concentrations in both cadm ium salts. In term s o f survival, both cadm ium salts w ere not toxic to earthworm Eisenia andrei as LC50 w ere >1000 m g ad /K g dry soil. H ow ever, the chronic toxicity o f cadm ium chloride and cadm ium sulphate w as extrem ely high. B iom ass reduction and reproduction w ere severely affected even at low er concentrations. The EC50 value for cadm ium chloride and cadm ium sulphate was 5.5 (2.6-8.4) m g a.i /kg dry soil and 6.3 (1.4- 11.3) m g a.i /kg dry soil respectively. Low est observed effect concentration (LOEC) for both salts w as 1 m g a.i /K g dry soil and N o observed effect concentration (N O EC) was <1 m g a.i /K g dry soil. O ur study concludes that use o f high C d containing fertilizers m ay risk beneficial soil organism s and application should be done w ith caution