Final answer:
In an engineered and sealed landfill, substances like methane gas, groundwater contamination, and heavy metals can be found due to waste decomposition. However, lychee, being organic matter, would decompose and not remain in the landfill as the other substances would.
Step-by-step explanation:
The question pertains to what substance buried in engineered and sealed landfills would not be found there. When considering landfill contents, methane gas, groundwater contamination, and heavy metals can all be present as byproducts of garbage decomposition and landfill operations. Methane is a common gas produced in landfills and can be harnessed for electricity, as in the case of Tucson Electric Power. Groundwater may become contaminated by leachates formed from decomposing waste. Heavy metals can be found in various electronics and batteries in the landfill. However, 'lychee,' which is a type of fruit, is not a substance that would remain contained in a landfill. Unlike the other substances, lychee would decompose, unlike long-lasting contaminants such as plastics or heavy metals.