UPTAKE OF ARSENIC AND METALS BY TADPOLES AT AN HISTORICALLY CONTAMINATED TEXAS SITE

On 14 May 1994, tadpoles were collected from Lateral Pond and Municipa l Lake in Bryan, Texas. These waters are immediately downstream from F infeather Lake which was directly contaminated during 53 years of indu strial production of arsenic (As)-based cotton defoliants. The tadpole s contained elevated levels of arsenic, chromium (Cr) and zinc (Zn). A s far as it is known, the mean concentrations of As (6.87 p.p.m. wet w eight) and Cr (6.91 p.p.m. wet weight) in cricket frog (Acris crepitan s) tadpoles were the highest ever reported in tadpoles. The Zn in the tadpoles exceeded the levels found in sediments by six to 11 times. Th e concentrations of As, Cr and Zn in Finfeather Lake in 1994 may have been toxic because tadpoles could not be found there. Ranid tadpoles a nd a newly transformed ranid frog found dead in Lateral Pond and Munic ipal Lake in 1994 may indicate that the elements reached toxic levels in some individual amphibians. The concentrations of As, Cr and Zn fou nd in the tadpoles in this study might be toxic to predators. Mortalit y of turtles showing symptoms linked to chronic exposure to As was rep orted in Finfeather Lake in 1973. Turtles were not reported in Finfeat her Lake again until 1996. Observations at Municipal Lake in 1994-1996 showed abundant tadpoles and turtles but no snakes, which also have n ot been seen at Finfeather Lake. This absence of snakes may indicate t hat their sensitivity or exposure to the existing contaminants is grea ter than that of frogs and turtles.