Uranium Bioaccumulation Dynamics in the Mayfly Neocloeon triangulifer and Application to Site-Specific Prediction

Abstract

Little is known about the underlying mechanisms governing the bioaccumulation of uranium (U) in aquatic insects. We experimentally parameterized conditional rate constants for aqueous U uptake, dietary U uptake, and U elimination for the aquatic baetid mayfly Neocloeon triangulifer. Results showed that this species accumulates U from both the surrounding water and diet, with waterborne uptake prevailing. Elevated dietary U concentrations decreased feeding rates, presumably by altering food palatability or impairing the mayfly's digestive processes, or both. Nearly 90% of the accumulated U was eliminated within 24 h after the waterborne exposure ceased, reflecting the desorption of weakly bound U from the insect's integument. To examine whether the experimentally derived rate constants for N. triangulifer could be generalized to baetid mayflies, mayfly U concentrations were predicted using the water chemistry and U measured in periphyton from springs in Grand Canyon (United States) and were compared to U concentrations in spring-dwelling mayflies. Predicted and observed mayfly U concentrations were in good agreement. Under the modeled site-specific conditions, waterborne U uptake accounted for 52−93% of the bioaccumulated U. U accumulation was limited in these wild populations due to a combination of factors including low concentrations of bioavailable dissolved U species, slow U uptake rates from food, and fast U elimination.

Effect of Nanoparticle Size and Natural Organic Matter Composition on the Bioavailability of Polyvinylpyrrolidone-Coated Platinum Nanoparticles to a Model Freshwater Invertebrate

“…That is, 30 to 80% of the Pt accumulated after relatively short NP exposures was rapidly lost during the first 24 h of elimination (first phase; Figure b,c). This initial rapid loss is not unusual for metals and likely represents loss of loosely bound or surface-bound metals. , Longer metal exposures typically decrease the proportion of metals stored in this fast-exchanging compartment . Elimination was not detected for the next 2–3 days (second phase).…”

“…This initial rapid loss is not unusual for metals and likely represents loss of loosely bound or surface-bound metals. 68,69 Longer metal exposures typically decrease the proportion of metals stored in this fast-exchanging compartment. 70 Elimination was not detected for the next 2−3 days (second phase).…”