Lead deposits, which accumulated in soil and snow during the 1960’s and 70’s, were primarily the result of leaded gasoline emissions originating in the United States. In the twenty years that the Clean Air Act has mandated unleaded gas use in the United States, the lead accumulation worldwide has decreased significantly.
A study published recently in the journal Nature shows that air-borne leaded gas emissions from the United States were the leading contributor to the high concentration of lead in the snow in Greenland. The new study is a result of the continued research led by Dr. Charles Boutron, an expert on the impact of heavy metals on the environment at the National Center for Scientific Research in France. A study by Dr. Boutron published in 1991 showed that lead levels in arctic (北极的) snow were declining.
In his new study, Dr. Boutron found the ratios of the different forms of lead in the leaded gasoline used in the United States were different
A. the Clean Air Act has not produced the desired results
B. lead deposits in arctic snow are on the increase
C. lead will stay in soil and snow longer than expected
D. the US is the major source of lead pollution in arctic snow
Passage Four
Three women who secretly buried an 80-year-old woman were put into prison at Birmingham yester day. Two of then), including the dead woman’s daughter, kept on collecting her pension (退休金) after her death until their secret was made known to others two years later. The court (法庭) heard that one of the women put on "an Oscar (奥斯卡金奖)--winning performance" by pretending to be the old woman asleep in bed when a social worker called five months after Mrs. Townsend’s death.
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