Relationships Between Concentrations of Individual Organics in Substrates and Tests Using Plants, Animals, and C18 Disks

ERDC TN-DOER-R3

September 2004

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

found by ANOVA (p<0.05; Table 4). The decrease in worm biomass with increasing IHC-DM

contribution was also in this case tentatively attributed to the concentrations of various metals in

the DM-mixtures, but no single metal could be identified that explained this biomass decrease

using multiple regression techniques. The biomass of worms exposed to DM mixtures containing

>20 percent IHC-DM was lower than that of the control worms (1.74 0.11 g DW cylinder-1;

19.8 0.23 individuals), but worm biomass was higher on the other DM mixtures than that of the

control, indicating that the latter DM mixtures provided acceptable substrates for biomass

formation.

Relationships Between Concentrations of Individual Organics in Substrates and

Tests Using Plants, Animals, and C18 Disks

No significant relationships between total organics concentrations in plants and worms, and

those in DM-mixtures, both expressed in mg compound per kg dry weight, were found.

However, statistically significant linear regressions were found between the 10log values of

selected, individual PCB and PAH compounds, expressed as mg compound per kg lipid of plants

and animals, expressed as mg compound per kg disk and per kg soil-DW of C18 disks, and the

log values of the same compound in the DM-mixtures, expressed as mg compound per kg

organic carbon (OC) (Table 5).

These relationships were statistically significant in:

Plant shoots

: at a 95-percent confidence level for FLU, FLA, PYR, and BAA.

: at a 90-percent confidence level also for PHE and BBF.

Plant roots

: at a 90-percent confidence level for ANT and PYR.

Worms

: at a 95-percent confidence level for ACE, FLA, IND, BGHI, and DIB.

: at a 90-percent confidence level also for BBF.

C18-Disks

: at a 95-percent confidence level for all organic compounds except NAP and DIB.

Based on the established significant linear regressions between the individual organic

compounds in the DM mixtures and the test devices, the authors conclude that L. perenne shoots

can be used as a bioaccumulation indicator for 6 of the 16 PAHs (i.e., FLU, PHE, FLA, PYR,

BAA, and BBF); roots only for 2 of the 16 PAHs (i.e., ANT and PYR); and earthworms for 6 of

the 16 PAHs (i.e., ACE, FLA, BBF, IND, BGHI, and DIB). The C18 disks represent a method

suitable to quantify the potential bioavailability (desorbability) of most organics (i.e., 14 of the

16 PAHs) and of Arochlor-1248.

The transfer of the organic compounds from the DM mixtures into the plants and worms was far

more irregular than into the C18 disks (Table 5). This was attributed in part to the lower mobility

of the compounds in the consolidated DM to which the plants and worms were exposed (versus

that in the slurries to which the disks were exposed) and in part to species- and trophic level-

specific selectivity of the plants and worms for individual compounds. The latter suggestion is