Development of calcium-modified biochar for enhanced phytoremediation of human-induced salt pollutants (HISPs)

Soil salinization is a major environmental hazard that limits land availability. Human-induced salt pollutants (HISPs) are regularly presented in large quantities on the contaminated site (such as brine leakages and salt-water spills), causing a devastating shock with high salt stress to the ecosystem. For instance, Saskatchewan resulted in a 48% drop in wheat production and a 0.3% decline in provincial GDP. As the calcium-modified biochar can potentially ameliorate the negative effects of HISPs on plants and improve the plant, phytoremediation with calcium-modified biochar can have increased detoxification of hazardous pollutants from sites. Therefore, the objective of our study was to develop a biochar-assisted phytoremediation employing diverse approaches to calcium modification for the sustainable removal of HISPs. The co-pyrolyzed calcium biochar achieved a remarkable removal rate of 18.06%, reducing salinity from 9.44 to 7.81 dS/m. During a 90-day long-term phytoremediation, the overall reduction rate of calcium-modified biochar stimulated the germination and growth of Thinopyrum ponticum. The result of post-treatment further indicated that co-pyrolyzed biochar with Ca transferred salt into the plant compared to Ca-coated biochar, which only immobilized HISPs on its surface. These results offer two different treatment approaches for diverse situations involving HISPs contamination, addressing current in-situ spills and providing a calcium-related biochar technology for further research in desalination.