Abstract: This paper studied the uptake of Pb absorbed on suspended gibbsite via gills of goldfish (Carassius auratus). Under conditions of the concentration of the particulate Pb varied while that of free Pb maintained at a constant level,the levels of both Pb and Al in the gills increased with increasing exposed Pb concentration.The increasing rate (slope 0.171) of Pb level in the blood with the Pb level in the gills was lower than that (slope 0.343) of soluble Pb exposure experiment.Partial Pb adhered on the gills did not transfer into blood.The ratio of Pb/Al in the gills was 1～2 orders of magnitude higher than that in the water,and on the microtome section of filament, the gibbsite particles adhered on gill mucus were observed, indicating the bioavailability of the particulate Pb uptake by the gills of goldfish.The major mechanism was: when the absorbed Pb on suspended particles was flowed into gill filaments,it was desorbed on the surface of gills,and then, passively diffused or transferred by carriers via gill cells into flood,and after the particles stayed on the surface of gill filaments for a short time,in company with sloughed mucus,they were released from the gills along with waterflow.

Key words: Lead, Goldfish, Particulate lead, Bioavailability