MERCURY DISTRIBUTION BY MICRO PIXE ANALYSIS IN STENOPSYCHE MARMORATA EXPOSED TO MERCURIC CHLORIDE

Abstract

Aquatic insects, such as caddisflies, are used as reference organisms for water pollution. The precise distribution of contaminated metals in the insect, however, remains unknown. In this study, we used micro PIXE analysis to examine mercury distribution in Stenopsyche marmorata, a typical caddisfly, exposed to mercuric chloride. The mercury level in the caddisflies after exposure to mercuric chloride at 1 mg/L for 5 days was 93.3 ± 25.0 μ g/g wet weight. Micro PIXE analysis also revealed a site-specific distribution of mercury in the insects. Mercury was high in the digestive tract, where it was localized in the basement membrane and the peritrophic membrane. Mercury was also detected in the tissue surrounding the digestive tract. Further examination of the tissue identified mercury in the fat body but not in the silk gland.