91色情片

Ferns can soak up poisonous arsenic from contaminated soil for as long as it
takes to clear a site, say researchers at the University of Florida. In W0
0061822, they reveal that the Chinese ladder brake fern, Pteris vittata,
grows very rapidly, obligingly collecting poison in its stems and roots where
it is easy to harvest. The researchers have found that arsenic concentrations
can exceed 5 grams in each kilogram of dried plant. Natural arsenic deposits are
a major health hazard in Bangladesh and West Bengal, where the poison
contaminates groundwater from shallow tube wells.