The foraminifera in the core samples were most abundant after 1950, when farmers began using some fertilizer, which is rich in nutrients.
核心样本中的有孔虫在1950年之后最多，当时农民开始使用一些营养丰富的肥料。
2
The fossils buried in Pleistocene and earlier ocean sediments were of foraminifera—small, single-celled marine organisms that secrete shells of calcium carbonate, or calcite.