Table 1 Harmonized variables for data extraction from 238 phytoremediation studies of sunflower, hemp, castor bean, and bamboo.

DOI

DOI (Digital Object Identifier) or a unique article identifier (UAI) in the absence of a DOI

This field contains the unique identifier of the research article

Species

Hemp (Cannabis sativa L.), Sunflower (Helianthus annuus L.), Castor bean (Ricinus communis L.), Bamboo (Bambusa vulgaris L., Phyllostachys edulis L., and P. praecox)

Used for identification of the industrial crop that was sampled for the data entry

Variety

Taxonomic level below the level of species

Identifying the plant variety that was used in research, if available

Location

Site where the soil was collected in the experiment, or where the experiment was conducted. Name and as provided in the reporting publication; includes geographic coordinates if provided

Contains information on growing conditions

Date

Research date was collected (if available) and includes years and date ranges

Element

Element measured in the experiment, reported as the atomic symbol

Oxidation State

Oxidation state of the identified element

Additional information of the experiment, if available

Treatment

Any specific treatments applied to the soil or plants during the research to modify growing conditions

Spiked Soil

Boolean value identifying if the data was collected from a plant grown in soils enriched with the toxic element

Chemical Form

The form of the chemical used to spike the soil

Soil Concentration

Elemental concentration in the soil

Information used for calculating bioconcentration factor (BCF)

Plant Component

Component of plant biomass that the data was collected from

Plant Concentration

Elemental concentration in plant tissue

Concentration Units

Units in which elemental concentration was measured

BCF

Bioconcentration factor. The elemental concentration ratio between plant tissue and the soil

Ability of plant to uptake the element from the soil

Manually calculated BCF

Boolean value identifying if the BCF calculated manually as opposed to being directly reported in the paper

Attributes of experimental and measurement methods

Dry weight

Boolean value identifying if calculation were done using formal dry weight

Natural soil

Boolean value identifying if the plants were grown in natural soil (clean or contaminated) as compared to artificial potting soil

Growing conditions

Soil pH

pH value of soil

Organic matter

Percent organic matter in the soil

Soil type

Whether the soil was natural, cleaned, polluted, commercial, spiked, or amended (e.g., with mulch)

Irrigation

Boolean value identifying if the plant was irrigated or not

Fertilization

Boolean value identifying if the plant was fertilized or not

Duration

Days between planting and harvesting

Note