[完成句子]Heavy metals are persistent; they do not break down to other chemicals in the environment. Industrially polluted sites usually undergo intensive clean-up and rehabilitation because heavy metals are a health concern once they enter the food chain. Some trace metals are alleged to cause cancer and are also known to cause poisoning.
广西快3开奖结果 Industrially contaminated sites usually require a thorough clean-up due to __________.
A、the persistence of heavy metals
广西快3开奖结果 B、industrially polluted soils
广西快3开奖结果 C、naturally polluted soils
D、rock and soil chemistry