Vermitoxicity of aged biochar and exploring potential damage factors

Area of Science:

• Environmental Science
• Soil Science
• Ecotoxicology

Background:

• Biochar is a soil amendment with changing properties upon aging.
• Aged biochar can be hazardous to plants and soil microbiota.
• The vermitoxicity of aged biochar and its risk factors remain unexplored.

Purpose of the Study:

• To systematically examine the vermitoxicity of aged biochar on earthworms (Eisenia fetida).
• To identify potential risk factors contributing to aged biochar's toxicity.
• To evaluate the ecological risks of aged biochar as a soil amendment.

Main Methods:

• Soil culture experiments with aged corncob biochar and Eisenia fetida.
• Acute toxicity bioassays using modified aged biochar and leaching solutions.
• Assessment of earthworm mortality, growth, behavior, and physiological-biochemical parameters.

Main Results:

• Aged biochar exhibited higher toxicity than fresh biochar, with reduced LC50 to 6.89%.
• Aged biochar caused earthworm death, significant growth inhibition (up to 36.6%), and avoidance behavior.
• Cellular damage included disrupted lysosomal membrane stability, altered antioxidant enzyme activities, and increased MDA content.

Conclusions:

• Aged biochar poses significant risks to earthworms, impacting survival, growth, and physiology.
• Volatile organic compounds (VOCs), improper pH, and extracts from aged biochar are potential harm factors.
• This research provides crucial insights into the long-term ecological toxicity of biochar, informing application standards.