In an investigation of the toxicity, to detritivores, of leaf material shed from poplar
trees used to remediate TCE and CCl4-contaminated ground water, acute and
chronic tests were performed with a terrestrial isopod (Armadillidium vulgare or
"pillbug") and an aquatic amphipod (Hyallela azteca or "scud").
This work was performed by Clemson University graduate student, Martha Sorbet, as her MS
degree thesis.
Feeding tests indicated that though fresh control or treated leaves are not palatable
to the isopods, weathered leaves from TCE and CCl4 processing poplars were
neither aversive nor acutely toxic. Growth and reproduction studies showed no adverse
affects from the leaf material over 10 week exposure periods.
Hyallela LC50s (96-hr, static) of the major metabolites found in the leaves,
trichloroacetic acid (TCA), dichloroacetic acid and trichloroethanol, were 214, 218 and
365 ppm, respectively. Growth and reproduction studies showed that TCA did not kill
Hyallela at doses up to 54 ppm (well above anticipated levels leached from the leaves) for
8 weeks, over half of the invertebrate's lifetime. Growth and fecundity declined somewhat,
but neither over 50%. The findings indicate that for two representative detritivores, the
fallen leaves from poplars used for TCE and CCl4 remediation pose little toxicological
risk.