The aspect of heavy metals that makes them particularly hazardous to ecosystems is their toxicity and persistence in the environment. Heavy metals, such as lead, mercury, and cadmium, can accumulate in living organisms, leading to harmful effects on health and the environment. They can disrupt biological processes, damage organs, and affect reproductive success. Additionally, heavy metals do not degrade over time, resulting in long-term environmental contamination that poses risks to wildlife and humans. This persistence and bioaccumulation factor make heavy metals significant environmental pollutants requiring careful management.