Metal concentrations and tissues distribution in larvae ofChironomus with reference to x-ray microprobe analysis

Atomic absorption, scanning electron microscopy and x-ray microprobe analysis were used to examine metal accumulation and localization in larval chironomids collected from two sites that differed in their extent of contamination. Lead, Fe, Cd, Cu, Ni, Zn, and occasionally, Al were detected in the midgut and anal papillae of chironomids, with the greatest frequency of detection occurring in the midgut of larvae collected from the more heavily contaminated site. Metal storage differed between the populations studied. Eighty-one percent of the spectra that had metals in detectable concentrations were of larvae from the contaminated site, while only nineteen percent were from the less contaminated site. Sixty percent of the spectra were from the midgut and fifteen percent were from the anal papillae of the contaminated population. Nine percent of the remaining spectra were from the midgut and nine percent were from the anal papillae of chironomids from the less contaminated site. For some elements, differences in metal storage between populations were suggestive of differences in metal tolerance.