Which industrial facility is most likely to produce sludge and heavy-metal wastes?
a. aleather tannery
b. amedical center
c. a nuclear power plant
d. a steel-smelting facility

The answer is A. A leather tannery. A tannery produces a sludge as a byproduct that is high in various toxic elements including chromium, a heavy metal that is highly toxic. Other pollutants produced include sodium, calcium, sulfur, magnesium, phosphate, copper, tin, lead, arsenic cadmium and zinc. Tannery effluent is an extremely toxic pollutant that could cause great harm if released into the environment, and for that reason, the tannery industry needs to be highly regulated and managed. 

Wetlands form where water and land meet. a lake with a wetland fringe can fill in with decayed plant and animal material to become a wet meadow. a pond can fill in to become a bog or fen. sediment can fill in a river marsh to become a swamp.flooding of coastal lowlands from rising sea levels has created broad coastal marshes that are protected from wave action by barrier islands or reefs. coastal wetlands also form when rivers deposit sediment as they reach the ocean. plants then take root and hold the soil firm against the forces of tides and waves.