Table 2. Description of Phytoreclamation Processes by Contaminant Class

Technical Note DOER-C3

May 1999

Some dredged material management plans may allow one or more of these processes to occur

concurrently or may require the processes to occur sequentially.

Table 2

Description of Phytoreclamation Processes by Contaminant Class

Contaminant Class

Major Plant Pathways

Phytoreclamation Process

Heavy metals

Uptake, Transformation

Extraction, Immobilization, Stabilization

Petroleum hydrocarbons

Degradation, Uptake ?

Degradation, Immobilization, Stabilization

Polychlorinated biphenyls

Degradation ?

Degradation, Immobilization, Stabilization

Pesticides

Uptake, Metabolism

Extraction, Degradation, Stabilization

Organotins

Uptake ?, ?

Degradation, Immobilization, Stabilization

Dioxins

Degradation ?

Degradation, Immobilization, Stabilization

Explosives

Uptake, Metabolism, Degradation

Extraction, Degradation, Stabilization

A FRAMEWORK FOR DETERMINING PHYTORECLAMATION SUITABILITY: Prior to

initiating an evaluation of the phytoreclamation framework, it is assumed that the physical and

chemical characterizations of the dredged material have been conducted and a determination has

been made that the material is not suitable for open-water placement. It is also assumed that the

dredged material is contaminated and will require some form of treatment prior to a beneficial use.

Available treatment alternatives include bioreclamation (Technical Note DOER-C4), chemorecla-

mation (soil washing, stabilization, etc.), or phytoreclamation. Once the phytoreclamation alterna-

tive is considered, an evaluation can be conducted using currently available testing protocols. A

framework for accomplishing the evaluation is shown in Figure 4. The first step is to determine a

strategy and set goals to measure success. Will plants be used to reduce contaminant concentrations

or reduce contaminant mobility? Will the dredged material be left in place or removed for reuse

elsewhere? What is the ultimate use of the dredged material? The answers to these types of

questions will dictate what the phytoreclamation goals must be in relation to Federal, State, and

local authority criteria or standards.

The next step is to determine the physicochemical characteristics of the dredged material, based on

the condition it will be in during the phytoremediation process. These characteristics will deter-

mine, in part, the selection of plant species and soil amendments necessary to ensure plant survival

and growth. The effects of plant selection and amendments can then be evaluated to select the most

suitable combination. These plant/amendment combinations are then evaluated to determine if the

set goals of contaminant reduction/stabilization are met. Reclaimed dredged material must then

pass biological and chemical evaluation for adverse effects. Failure to meet these goals or avoiding

adverse effects criteria may require modification and additional testing of the phytoreclamation

process or evaluation through the chemoreclamation or bioreclamation framework. Materials

meeting the stated goals and passing the adverse effects criteria are then suitable for beneficial uses.

TESTS FOR ASSESSMENT OF PLANT GROWTH AND EFFECTS OF AMENDMENTS:

For purposes of cleanup or stabilization, the physical and chemical characteristics of the dredged

material must be determined prior to designing a phytoreclamation project. The recommended tests

include contaminant analysis, pH, texture, salinity, total organic carbon, lime requirement, cation

exchange capacity, carbon:nitrogen ratio, phosphorus, nitrogen, and potassium, described in WES