在二十世纪六七十年代,铅沉积就在土壤和雪中不断累积,这主要是美国的含铅汽油排放的后果。
Lead deposits, which accumulated in soil and snow during the 1960s and '70s, were primarily the result of leaded gasoline emissions originating in the United States.
一旦完成了这个,河流带来的淤泥会沉积在此处,回报是丰厚的:产量是被雨水滋养的土壤的四到五倍。
Once this was done and the silt carried down by the rivers was planted, the rewards were rich: four to five times what rain-fed earth would produce.
该小组正在调查碳酸钙矿物中的元素,这些碳酸钙矿物沉积于距今2至170万年的湖内部及周边的淤泥和土壤中。
The team is investigating elements in the mineral calcium carbonate, which were deposited in the mud and soil in and around a lake between two and 1.7 million years ago.
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