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.
 Someone could come into contact with cyanide by breathing air, drinking water, eating food or touching soil that contains the chemical.  Cyanide enters water, soil or air as a result of both natural processes and industrial activities.In air, cyanide is present mainly as the gas hydrogen cyanide.Someone could come into contact with cyanide by breathing air, drinking water, eating food or touching soil that contains the chemical.  Cyanide enters water, soil or air as a result of both natural processes and industrial activities.