Lead in Stormwater FAQs
Lead is a soft, dull-grey metal that is extracted from ore deep within the earth’s crust.[viii] It has a shiny metallic luster after being freshly cut, and is highly malleable and corrosion resistant.[x] It also has a high propensity for adsorbing x-rays and gamma rays.[xi] Lead has the highest atomic mass of all other stable, non-radioactive elements. Lead is found in both particulate (Pb) and dissolved forms (Pb2+) in industrial stormwater runoff.
Lead is used for its unique characteristics although it is now less widely used in domestic products because of its toxicity to humans.[xii] Domestic uses of lead in gasoline and paint have stopped in the U.S. and other countries. Common uses of lead today are lead acid batteries as used in automobiles, bullets and shotgun shot, fishing sinkers, industrial grade and non-domestic paint, boat keels, radiation shielding, and soldering.[xiii]
Lead enters the environment through the manufacture and use of consumer products, and by contamination of soils and water. Groundwater can become contaminated by mine dewatering operations.[xvii] Other examples of contamination sources include lead-based paints on buildings pre-dating the 1970’s.[xviii] and industries that manufacture, recycle, demolish, or refurbish products contain lead. Lead in these forms can make its way into waterways and human freshwater drinking sources through stormwater runoff.
Raw and formed lead (image courtesy of Wikipedia)
Lead should be removed from stormwater runoff because low levels of it in drinking water and in the environment can have severe health consequences for humans and wildlife. Ingested even at low levels, lead may cause a range of human health effects including learning disabilities, kidney problems and high blood pressure.[i] Children under seven-years-old are most at risk because their brains are still developing.[ii]
Unlike other trace elements, lead is neither essential nor beneficial for living organisms.[iii] Lead compounded with organic elements are generally more toxic than inorganic lead compounds. Adverse effects of lead in water on aquatic species occur at concentrations of 1.0 – 5.1 ug/l and include reduced survival, impaired reproduction and reduced growth.[iv]
Lead poisoning in birds occurs at higher levels (measured in milligrams per kilogram of body weight) usually from ingestion of lead shots.[v] A bird with lead poisoning will have physical and behavioral changes, including loss of balance, gasping, tremors, and impaired ability to fly.[vi]
Lead can be present in stormwater in both particulate and dissolved states. Enhanced, passive media filtration can be used to remove particulate lead. If further reduction is necessary to remove dissolved lead, advanced polishing technologies can be used. Both types of BMPs combined in a treatment train will remove total lead from stormwater prior to discharge to help facilities meet benchmarks or NALs. The Aquip passive media filter and the Purus metals polisher combined offer an advanced level of lead removal from stormwater. Learn more about our stormwater media filtration and polishing technologies.
Lead in rooftop runoff is typically found in a dissolved state. Dissolved lead can be removed from rooftop stormwater runoff by running it through an advanced, passive media filter connected to a downspout. Our Zinc-B-Gone downspout units provide this advanced level of rooftop stormwater runoff treatment. Find out more about our downspout filtration units here.