| Abstract | Metal contamination of soil represents a severe threat to human health via natural resources and food production practices due to the accumulation of heavy metals and metalloids via emissions displaced from rapidly expanding industrial sources. The addition of organic matter in the form of biochar to metal-contaminated soils could significantly impact the mobility and chemistry of three commonly found metals Cadmium (Cd), Zinc (Zn), and Lead (Pb), while creating suitable conditions for non-edible agricultural plants to be utilized for bioremediation practices. This study utilized two types of biochar 1) derived from wood chips (BC1), and 2) derived from horse manure (BC2), at two rates (1% and 4% w/w), as an amendment to metal-contaminated soil (MCS) to provide an in-depth physicochemical investigation of the MCS and tested biochars, comparing the metal chemistry in the MCS after the addition of biochar. Before the influence of the applied biochar treatments, all three metals exceeded the global average values for metal in soil; Cd 25-fold, Zn 56-fold, and Pb 127-fold. It was also confirmed that the addition of tested biochar types decreased the levels of high metal concentrations within the contaminated soil matrix by approximately 3% for Cd, 34% for Zn, and 93% for Pb. SEM analysis confirmed that micro to nano pore structure, surface area, and viable space for gas exchange in the amended soil was positively altered from the addition of the biochar types. Lab analysis confirmed that both biochar types enriched the soil with organic matter, N, C, P, K, S, and dropped the heavy-metal concentration within the test-crop by 1-3%. Thus, sowing of the test crop with biochar derived from wood chips and horse manure within metal-contaminated soil, leads to the amelioration of the soil, from metals such as Cd, Zn, and Pb. The amelioration of metal-contaminated soil with a particular biochar type could significantly affect the transfer of metals from a contaminated matrix to food production and water systems, thus allowing the chemical amelioration, and bioremediation of natural or artificial ecosystems globally that have been contaminated by heavy metals. |
