H.3 Laboratory Plant Bioaccumulation Procedures

Table H.2

-1

DTPA-Predicted Plant Metal Concentrations (ug g ) and Total

Plant Bioaccumulation (ug)

Wet

Oven Dry

Total

Metal

Concentration

bioaccumulation

Concentration

bioaccumulation

0.576

0.977

0.324

0.608

Arsenic

2.23

49.54

1.95

31.67

Cadmium

12.33

15.93

9.33

22.10

Chromium

21.02

178.48

26.04

162.5

Copper

2.07

6.86

1.63

9.81

Lead

0.01

-0.38

0.048

-1.59

Mercury

6.04

-20.62

5.32

5.45

Nickel

35.09

1321

44.1

2202

Zinc

H.3 Laboratory Plant Bioaccumulation Procedures

H.3.1 Plant bioaccumulation/toxicity assessment

The plant bioaccumulation procedure consists of the exposure of index

plants to dredged material and a reference soil or sediment. The dredged

material and reference material are prepared to simulate wetland conditions or

are processed by drying and oxidation to simulate terrestrial conditions before

being planted with seedlings of the appropriate specie. Spartina alterniflora

(SA) and is used for saline wetland conditions. Cyperus esculentus (CE) is used

for fresh wetland, fresh terrestrial, and saline terrestrial conditions. The

procedure calls for sediment exposure through maturity of the plant in an

environmentally controlled greenhouse. Aboveground plant tissues are harvested

and analyzed for COC concentrations.

H.3.2 Apparatus and materials

Apparatus. The apparatus for performing the plant bioaccumulation

procedure is shown in Figure H.1. It is basically a double bucket with an inner

bucket that allows water flow through holes in the bottom. The purpose is to

facilitate adequate watering by adding water to the outer bucket and allowing

movement of water by hydraulic pressure into the inner bucket through the holes

in the bottom. A soil tensiometer placed in the sediment indicates when enough

water has been added to bring the sediment to approximately field capacity

moisture content.

Materials. Tubers of yellow nutsedge (Cyperus esculentus) can be

obtained through commercial suppliers (for example, Valley Seed Services,

Fresno, CA, or Wildlife Nurseries, Oshkosh, WI). Tubers are germinated prior

to use in the plant bioaccumulation procedure. The tubers are first rinsed in

distilled water and then placed between paper towels and kept moist and at 23 οC

in a lighted germination chamber. Generally, the germination rate is low and the

Appendix H Plant Bioaccumulation Procedures