Final answer:
Coal-fired power plants are the type of electricity generating power plants that regularly release toxic metals such as mercury and lead into the atmosphere.
Step-by-step explanation:
The type of electricity generating power plant that regularly releases toxic metals such as mercury and lead into the atmosphere is a coal-fired power plant. These power plants burn coal to produce electricity, which involves releasing various pollutants, including mercury, lead, and other heavy metals.
This is not only a concern for air quality but also for the ecosystems that may be affected by the fallout from the plant's emissions. Options like nuclear power plants, natural-gas-fired power plants, and petroleum-fired power plants have different profiles of emissions and waste products. For instance, nuclear power plants do not emit these heavy metals into the atmosphere during normal operation, but they do produce radioactive waste which requires careful, long-term management.