Evaluation of industrial hemp cultivar and biochar rate to remediate heavy-metal-contaminated soil from the Tar Creek superfund site

Authors: THURSTON, D - University Of Arkansas; BRYE, K - University Of Arkansas; MILLER, D - University Of Arkansas; Moore, Philip; JOHNSON, D - University Of Arkansas; RICHARDSON, M - University Of Arkansas

Submitted to: Soil Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/6/2024
Publication Date: 11/8/2024
Citation: Thurston, D.V., Brye, K.R., Miller, D.M., Moore Jr, P.A., Johnson, D.M., Richardson, M. 2024. Evaluation of industrial hemp cultivar and biochar rate to remediate heavy-metal-contaminated soil from the Tar Creek superfund site. Soil Systems. 8(4). Article 114. https://doi.org/10.3390/soilsystems8040114.
DOI: https://doi.org/10.3390/soilsystems8040114

Interpretive Summary: Soil polluted with cadmium (Cd), lead (Pb), and zinc (Zn) at the Tar Creek superfund site in northeast Oklahoma remains a threat to both humans and the local environment. Phytoremediation is a method of removing heavy metals in soil where plants take up the metals. Adding biochar to soil has also been shown to reduce metal availability. The objective of this greenhouse study was to evaluate the effects of industrial hemp cultivar (‘Carmagnola’ and ‘Jinma’), biochar rate (0, 2, 5, and 10% by volume), soil contamination level (low, medium, and high), and their interactions on above- (AG) and belowground dry matter (DM) and AG tissue concentrations and uptakes of Cd, Pb, and Zn after 90 days of growth in naturally contaminated soils from the Tar Creek superfund site. Aboveground dry matter production was highest in the low and smallest in the high-contaminated soil and was unaffected by cultivar or biochar. Averaged across biochar rates, aboveground tissue-Pb and -Zn concentrations from the high-’Carmagnola’ and -’Jinma’ combinations were at least 2.4 times greater than from the other four soil-cultivar combinations. Averaged across cultivars, above ground tissue-Pb uptake in the high-5 and high-10% biochar combinations were at least 2.7 times greater than in the high-0 and high-5% BC combinations, which did not differ. Results indicate that both ‘Carmagnola’ and ‘Jinma’ may suitable choices for phytoremediation of mixed Cd-, Pb-, and Zn-contaminated soil when grown in combination with 5 or 10% (v/v) biochar.

Technical Abstract: Soil contamination by cadmium (Cd), lead (Pb), and zinc (Zn) at the Tar Creek superfund site in northeast Oklahoma remains a threat to the environment and local ecosystem. Phytoremediation with industrial hemp (Cannabis sativa L.) and the use of biochar (BC) have been independently shown to be effective methods to remediate heavy-metal-contaminated soils. The objective of this greenhouse study was to evaluate the effects of industrial hemp cultivar (‘Carmagnola’ and ‘Jinma’), biochar rate (0, 2, 5, and 10% by volume), soil contamination level (low, medium, and high), and their interactions on above- (AG) and belowground dry matter (DM) and AG tissue concentrations and uptakes of Cd, Pb, and Zn after 90 days of growth in naturally contaminated soils from the Tar Creek superfund site. Aboveground DM was largest (P < 0.01) in the low- (0.06 g cm-2) and smallest in the high-contaminated soil (0.03 g cm-2) and was unaffected (P > 0.05) by cultivar or BC rate. Averaged across BC rates, AG tissue-Pb and -Zn concentrations from the high-’Carmagnola’ and -’Jinma’ combinations were at least 2.4 times greater than from the other four soil-cultivar combinations. Averaged across cultivars, AG tissue-Pb uptake in the high-5 and high-10% BC combinations were at least 2.7 times greater than in the high-0 and high-5% BC combinations, which did not differ. Results indicate that both ‘Carmagnola’ and ‘Jinma’ may suitable choices for phytoremediation of mixed Cd-, Pb-, and Zn-contaminated soil when grown in combination with 5 or 10% (v/v) BC.