SEDIMENT TOXICITY STUDY OF CCA-C-TREATED MARINE PILES

A study was undertaken to demonstrate the effects of a 10-day exposure to sediments mixed with leachate from marine piles made from southern pine that were treated with chromated copper arsenate Type-C (CCA-C) treated to a retention of 40 kg/m(3) (2.5 pcf) and untreated southern pine piles. The leachates were tested on the benthic amphipod, Ampelis ca abdita. The biological endpoint used to establish effects was organ ism survival. Leachate obtained during a 28-day period was dosed onto both low organic carbon and high organic carbon sediments. The Ampelis ca abdita were exposed to each type of sediment and were dosed with co ncentrations of leachates ranging from 10 to 100 percent. The componen ts of CCA-C, copper, chromium and arsenic, were measured during the pr eparation of the leachate, in sediment mixtures, and in the overlying and interstitial water in the exposed vessels. The 10-day exposure was maintained under static conditions with continuous lighting to ensure maximum exposure to sediment. Results showed that leaching of copper, chromium, and arsenic from properly treated and fixed CCA-C-treated w ood does not occur at concentrations that would adversely affect the s urvival of these organisms exposed to the sediment, Leachate from the treated piles also had no significant effect on water quality. The stu dy is significant, in part, because its design imitated the natural ma rine environment more closely than other studies published on this top ic.