SURVEY OF CADMIUM LEVELS IN VEGETABLES AND SOILS OF GREATER SYDNEY, AUSTRALIA

Cadmium is similar to 10% of root and leafy vegetables sold through th e Sydney Market exceeds the maximum permitted concentration (MPC) set by the Australian New Zealand (ANZ) Food Authority (0.005 mg kg(-1) fr esh weight). The leafy vegetables are mostly produced in the Greater S ydney Region; therefore, we investigated Cd contamination on the soils and vegetables of the Region. The crops and topsoils (0-15 cm) from 2 9 farms and uncropped (background) top soils were sampled and analyzed . Fruit generally had the lowest Cd levels and leafy vegetables the hi ghest, with 0 and 27% exceeding the MPC. Cadmium in cropped soils was 0.11 to 6.37% mg kg(-1) (mean 1.33 mg kg(-1)) and in background soils averaged 0.36 mg kg(-1). Soils derived from shale had the highest back ground Cd levels. Additions of P, Zn, and Cd in fertilizer and poultry manure explained significant proportions of the increases in soil con centrations of P (r(2) = 0.62, P < 0.001) and Zn (r(2) = 0.29, P < 0.0 5), but not of Cd. Cadmium increases were more closely related to incr eases in Zn (r(2) = 0.26) and exchangeable cations (r(2) = 0.34), whic h result from a history of heavy, annual applications of poultry manur e. Typical rates of Cd addition were about 10 times and sustainable ra te. Finally, the ANZ environmental investigation guideline for soil Cd (3 mg kg(-1)), was a poor indicator of crop contamination, because si milar to 0.3 mg Cd kg(-1) soil resulted in lettuce (Lactuca sativa L.) and broccoli (Brassica oleracea) exceeding the MPC.