Potential risks of the natural nanoparticles from the acid mine drainage and a novel approach for their toxicity assessment

Acid mine drainage (AMD) is a serious environmental problem due to its acidic pH and high contents of heavy metal ions. Thus, assessment of AMD toxicity has been widely investigated at individual, physiological and molecular levels using various test organisms. However, most studies focused on the toxicity of whole AMD while very few studies identified the toxicity of natural nanoparticles (NPs) originated from AMD. In AMD systems, natural NPs such as amorphous hydroxides, ferrihydrites, schwertmannite and goethite seemed to be formed, which could induce letahl and sublethal toxicity toward aquatic organisms. In this review, we summerized the toxicity of whole AMD and manufactured NPs, and suggested a novel approach for toxicity assessment of natural NPs from AMD.