Bioaccumulation and toxicokinetics of arsenite (As III) in the aquatic bioindicator Pomacea canaliculata using radiotracer analysis

Abstract

This study examines the kinetics of absorption, distribution and accumulation of arsenite (As III) in the freshwater gastropod Pomacea canaliculata using a short-lived tracer (76As III). The toxicokinetic model indicate that the gills play a crucial role in the As III uptake, with uptake rates significantly exceeding those of release back into the aquatic environment. The movement of As III from the gills to the hemolymph has low exchange rate. The hemolymph acts as a convective transport medium, facilitating the distribution of As III to various organs of accumulation and elimination within the snail. The majority of As III detected in the hemolymph is directedtoward the kidney, stomach, coiled gut and digestive gland. Following feeding, the maximum As inventory (90 %) was reached at 24 h, after which an elimination phase with approximately 4 % between 24 and 96 h. According to our toxicokinetic model, feces is the primary route of elimination. By 96 h, As III is localized in the digestive gland (70 %) and visceral mass (6 %). Furthermore, tissue accumulation shows a linear correlation with increasing As III concentrations in the surrounding water. By integrating 76As radiotracer assays withphysiological information, we gain valuable insights in the toxicokinetic of both As III and As V. We hypothesize that biotransformation may occur between these two inorganics As forms at the tissue level.