Lead (Pb) and water Lead and water: reaction mechanisms, environmental impact and health effects. Seawater contains trace amounts of lead (2-30 ppt). On average rivers contain between 3 and 30 ppb. Phytoplankton contains approximately 5-10 ppm lead (dry mass), freshwater fish approximately 0.5-1000 ppb, and oyster approximately 500 ppb.
https://www.lenntech.com/periodic/water/lead/lead-and-water.htm

