Toxicity assessment of the utilization of AOD slag as a mineral fertilizer for pakchoi (Brassica chinensis L.) planting

The application of argon oxygen decarburization (AOD) slag as a mineral fertilizer can be employed as an effective and environment-friendly approach. In this study, batch leaching tests and pot experiments were performed to assess the toxicity exhibited by AOD slag fertilization for pakchoi (Brassica chinensis L.) planting. pH, Eh and element leaching concentration were measured to examine the effect exerted by AOD slag addition on physicochemical properties exhibited by soil. The effect of AOD slag fertilization on pakchoi growth was determined by measuring its physiological and biochemical parameters. Moreover, the heavy metal accumulation, biological accumulation coefficient (BAC), estimated daily intake (EDI) and target hazard quotient (THQ) were identified to assess the health risks. As indicated from the result, adding AOD slag could increase pH and the leaching concentrations of Ca, Si, Cr and Ti, while decreasing the leaching concentrations of Fe, Ni, Cd, Hg and Pb in soil. With the increase in the addition rate, the concentrations of Mg, Al and Mn were elevated and then started to decrease at the rates of 2%, 8% and 2%, respectively. Low rates (<= 1%) of AOD slag fertilization positively impacted pakchoi growth, whereas high rates exerted an opposed effect. The calculated EDI and THQ values were all less than 1. The consumption of the pakchoi grown on the AOD slag fertilized soil was at low risk. For plant growth perspective, the utilization amount of AOD slag as a mineral fertilizer for pakchoi planting should not exceed 1%.