Zinc is naturally present in water. The average zinc concentration in seawater is 0.6-5 ppb. Rivers generally contain between 5 and 10 ppb zinc. Algae contain 20-700 ppm, sea fish and shells contain 3-25 ppm, oysters contain 100-900 ppm and lobsters contain 7-50 ppm.
Cyanides (more exactly as cyanogenic glycozides) exist in cassavaroots, and fruit seeds as apricots, prunes, peaches, almonds etc. Cyanide is historically found in the seeds â¦of some fruits. Applesseeds contain cyanide, but a person would have to eat a lot ofapple seeds for the cyanide to have any negative effects. Cyanide is natural found in certain foods. This includes cassava,almonds, pits of some types of fruit, and Lima beans.
Species of Indigofera were cultivated in Peru, India, East Asia and Egypt in antiquity. The earliest direct evidence for the use of indigo dates to around 4000 BCE and comes from Huaca Prieta, in contemporary Peru. Pliny mentions India as the source of the dye, imported in small quantities via the Silk Road.