a layer of a substance that has been left somewhere, especially by a river, flood, etc., or is found at the bottom of a liquid （尤指河流、洪水、液体等的）沉积物，淤积物
a layer of a substance that has been left somewhere, especially by a river, flood, etc., or is found at the bottom of a liquid （尤指河流、洪水、液体等的）沉积物，淤积物