AUTHOR=Zulfqar Amna , Niazi Nabeel Khan , Saqib Zulfiqar Ahmad , Shahid Muhammad , Hussain Khalid , He Zhenli 

TITLE=Phytoaccumulation of chromium by hemp and ryegrass in rice husk biochars, nano-zero valent zinc and vermicompost amended tannery wastewater soil

JOURNAL=Frontiers in Environmental Science

VOLUME=Volume 13 - 2025

YEAR=2025

URL=https://www.frontiersin.org/journals/environmental-science/articles/10.3389/fenvs.2025.1558255

DOI=10.3389/fenvs.2025.1558255

ISSN=2296-665X

ABSTRACT=Chromium (Cr) contamination of soil threatens environmental and human health, necessitating effective and sustainable remediation solutions. Here we explored the impact of rice husk biochar (RH-BC), nano-RH-BC, vermicompost, nano-zero valent zinc (nZVZn), and manganese-modified RH-BC (MnO/RH-BC) on phytoaccumulation of Cr by industrial hemp (Cannabis sativa L.) and ryegrass (Lolium perenne L.) grown in tannery wastewater-impacted Cr-contaminated soil in a pot trial. Results revealed that maximum shoot Cr concentration was observed in ryegrass with nZVZn mainly in first cutting (45 mg kg-1 DW) followed by vermicompost (42 mg kg-1 DW) > RH-BC (40 mg kg-1 DW) > nano-RH-BC (35 mg kg-1 DW) ∼ MnO/H-BC (34 mg kg-1 DW). In the case of hemp, nZVZn led to maximum shoot Cr concentration (42 mg kg-1 DW) and minimum with RH-BC (4 mg kg-1 DW); notably, hemp survived only for the first harvest. The SPAD value (chlorophyll content) was the highest with MnO/RH-BC for ryegrass and RH-BC for hemp (40 and 51, respectively) and minimum with nZVZn. Results showed that the RH-BC enhanced shoot dry weight of hemp by 664% compared to control, and MnO/RH-BC increased for ryegrass by 400%, 93%, 55%, and 21% at first, second, third, and fourth harvests, respectively. Overall, RH-BC and MnO/RH-BC-amended soils improved plant tolerance against Cr, highlighting their potential for phytoremediation of Cr-contaminated soil. Based on the findings, it is evident that Cr phytoaccumulation is a complex process and varies with plant species and amendment type, which are key factors to consider in future field trials on tannery wastewater-impacted Cr-contaminated soils.