Can corn straw and its pyrolytic biochar be used to mitigate the toxicity of CuO NPs to wheat seedlings?

Abstract

In order to understand whether corn straw (CS) and straw-derived biochar (CB) can be used as soil amendments to alleviate soil contaminated with metal oxide nanoparticles, CS and CB prepared by pyrolysis at 300 °C (with a weight ratio of 2% and 5%) were added to two types of soil contaminated with copper oxide nanoparticles (CuO NPs) to study the effects of CS and CB application on soil properties, wheat seedling growth, and metal transport. Our results showed that both 2% and 5% additions of CS and CB enhanced the nitrogen, phosphorus, and potassium fertility of both soils. In red earth (acidic), the addition of 2% and 5% of CB significantly increased soil pH (9.24% ~ 18.4%), wheat growth (12.2% ~ 14.9%), chlorophyll content (significantly increased by 32.3% for 2% CB treatment), and decreased antioxidant enzyme activity and membrane lipid peroxidation. In fluvo-aquic soil (alkaline), CS and CB did not increase soil pH, only 5% of CB significantly promoted wheat growth (by 11.0%), and decreased antioxidant enzyme activity, whereas 2% of CB reduced chlorophyll content (by 22.2%). Furthermore, 2% and 5% of CS and CB affected the transport of Cu in wheat, decreasing the translocation factor in red earth but increasing it in fluvo-aquic soil. Principal component analysis showed that 5% of CB had the best alleviating effect on CuO NPs toxicity in red earth, compared to CS. Taken together, CB obtained by pyrolysis at 300 °C appears to be an effective soil amendment specifically for red earth.Highlights• Corn straw (CS) and straw-derived biochar (CB) were used to mitigate CuO NP toxicity• 5% of CB showed the best mitigation effect on CuO NP toxicity in red earth• CS and CB had no significant mitigation on CuO NP toxicity in fluvo-aquic soilGraphical