Bioaccumulation and Toxicity in Worms

ERDC TN-DOER-R3

September 2004

cultivated on the 33-percent IHC DM mixture may have been adsorbed to the tiny roots anchor-

ing the plants to the substrate. These roots were so small that they were not harvested separately.

It may also have been adsorbed through volatilization from the substrate surfaces.

Concentrations in plant roots from dry DM mixtures were far higher than from wet DM

mixtures.

PAHs (sum of 16 PAHs) were recovered from roots and shoots (Table 3). PAH concentrations

were higher in roots than in shoots and they increased with increasing PAH concentration in the

DM mixture. This may indicate that most PAHs were taken up by the plants and translocated

from roots to shoots, since a large part of the volatile PAHs had been lost during drying of the

IHC-DM (Material and Methods Section `Substrates' p. 5). The high PAH concentrations in

plant shoots cultivated on the 33-percent IHC DM mixtures may also have been adsorbed to the

tiny roots anchoring the plants to the substrate, as suggested for the PCBs. PAH concentrations

were far higher in plant roots from dry than from wet DM mixtures. No significant relationships

between organics concentrations in plant tissues and those in DM mixtures, both expressed as

milligrams compound per kilograms dry weight, were found. However, upon further inspection

of the data, significant relationships were identified; these are discussed under "Relationships

between concentrations of individual organics in substrates and tests using plants, animals, and

C18-disks," p. 10.

In the plant material, various metals accumulated up to considerable concentrations (Table 3).

Shoot concentrations of Cr, Pb, and Zn exceeded CSCLs for plants in the dry 20-percent IHC

mixtures, while the concentration of Zn came close to the phytotoxic level recently determined

for another grass species, Cynodon dactylon (bermudagrass; Best et al. 2003).

Plant biomass was significantly affected by percent IHC contribution to the DM-mixture, as

found by ANOVA (p<0.05; Table 3). Substrates with an IHC-DM contribution exceeding

33 percent did not support plant growth. The decrease in plant biomass with increasing IHC-DM

percent was tentatively attributed to the various metals in the DM mixtures, but no single metal

could be identified that explained this biomass decrease using multiple regression techniques.

Biomass was significantly higher in plant material harvested from the wet than from the dry DM

mixtures (p<0.001; Table 3). The biomass of plants exposed to DM mixtures, including the ref-

erence, was always lower than that of the control plants (226 23.45 g DW m-2), indicating that

all DM mixtures provided less than optimal substrates for biomass formation.

Bioaccumulation and Toxicity in Worms: In the worms, both Arochlor1248 and PAHs

accumulated. Arochlor1248 and PAH concentrations in worm tissues were significantly affected

by percent IHC contribution to the DM mixtures, as found by ANOVA, with PAHs accumulating

more gradually than PCBs (Table 4). No significant relationships between organics concentra-

tions in worm tissues and those in DM-mixtures, both expressed as mg compound per kg dry

weight, were found.

In the worms, various metals accumulated up to considerable concentrations (Table 4). In the

DM mixtures containing ≥10 percent IHC-DM, only the zinc concentrations exceeded the CSCL

for worms.