CR(VI) phytoremediation by hairy roots of Brassica napus: assessing efficiency, mechanisms involved, and post-removal toxicity

PEROTTI, ROMINA; PAISIO, CINTIA ELIZABETH; AGOSTINI, ELIZABETH; FERNANDEZ, MARÍA INÉS; GONZÁLEZ, PAOLA SOLANGE

ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH

SPRINGER HEIDELBERG

Año: 2020 vol. 27 p. 9465 - 9474

0944-1344

Industrial activities such as leather tanning involve the use of highly toxic inorganic pollutants, like Chromium (Cr). This workevaluated Cr(VI) remediation by hairy roots (HR) of Brassica napus, paying close attention to the mechanisms involved and thetoxicity of post-removal solutions. Results showed that these roots were capable of tolerating concentrations of up to 10 mg L−1Cr(VI), while higher concentrations were toxic for HR development. Removal efficiency was assessed through the use of syntheticsolutions containing different initial Cr(VI) concentrations (2, 5, or 10 mg L−1). Regardless of these initial concentrations, the highestremoval efficiency values were between 80 and 90% after 24 and 48 h of treatment, using a 2.0 g inoculum. The mechanismsinvolved were Cr accumulation (60%) and to a lesser extent, adsorption to the root biomass (30%). A fraction of Cr(VI) wasintracellularly reduced to Cr(III), which suggests reductases may have played a role. Additionally, post-removal toxicity wasevaluated through two bioassays (Lactuca sativa L. and AMPHITOX test) after the removal of 10 mg L−1 Cr(VI). The treatedsolutions showed moderate phytotoxicity for L. sativa L. and no toxicity for R arenarum. The ability of HR to remove 10 mg L−1Cr(VI) from real tannery effluents collected from a regional industry (Córdoba province, Argentina) was also determined. The highremoval efficiency observed (98%) demonstrates this system can be successful in treating complex wastewaters.