G.3.2.1 Test variations.

G.3.2.1 Test variations.

Laboratory Procedure with Sod. This procedure considers the potential

effects of vegetation on bioaccumulation by earthworms (Kay, Scolten, and

Bowmer 1988). This variation is conducted with Bermuda grass planted in the

cylinders (Skogerboe et al. 1996). The procedure differs from the above as

follows; On Day 0, 1 gm of Bermuda grass seeds are spread over the cylinder

surface. Seeds are covered with 1mm of peat moss and lightly watered with

reverse osmosis (RO) water. Each cylinder receives 125 mL of a dilute

(600 mg/liter of water) solution of soluble plant food (13-13-13), during the first

2 weeks to enhance seed sprouting. Excess water is collected in plastic trays and

poured off. On Day 30, earthworms are added. On Day 60, Bermuda grass is

harvested, earthworms are counted and weighed, and both grass and earthworms

are prepared for chemical analysis. The following alterations are made in the

temperature and lighting test conditions to promote grass growth: temperature

22 EC (night) to 29 EC (day), acceptable lighting is 400 lux illumination for a

period of 14 hr light/10 hr dark.

In Situ Field Procedure. An in situ field bioaccumulation procedure may be

used. This procedure is very similar to the laboratory procedure described

above, with a 7.5-l polyethylene bucket with screen-covered holes in the base

and lid to allow air and water but not earthworm exchange. Test containers are

implanted 25 cm deep (soil level) in the dredged material in place in the CDF

and filled with the material removed from the hole (Simmers et al. 1986).

G.3.2.2 Chemical analysis.

Chemical analysis of earthworm tissue for the animal bioaccumulation COC

should follow the tissue analysis guidance in Chapter 9 of the ITM

(USEPA/USACE 1998).

G.3.3 Data Presentation and Analysis

Data Presentation.

Data should be presented in tabular format, listing tissue concentration of

each COC by organism and by sediment type (e.g., dredged material and

reference). Although bioaccumulation tests cannot be used to quantify toxicity,

any mortality that occurs during bioaccumulation testing should be documented.

Data Analysis.

At the end of the 28-day test period, concentrations of COC in the tissues of

earthworms in the dredged material should be statistically compared to

concentrations of COC in worms in the reference material. The results of this

evaluation are interpreted according to the Tier III guidance in Chapter 8.

Concentrations of COC in the tissues of earthworms archived at the initiation of

the exposure may provide perspective helpful in reaching a Tier III decision.

Appendix G Animal Bioaccumulation Test Procedures