Heavy metals such as lead and arsenic can be found in both urban and rural environments. Old landfills and old orchards can retain high levels of metal contamination in the soil even when they are no longer used as such. Factory sites where chemicals are improperly disposed of and mining waste piles are also potentially hazardous areas to live in.
The U.S. Department of Agriculture identifies mining, manufacturing and use of synthetic products as the source of heavy metal contamination in soil. Synthetic products such as chemical pesticides and waste materials from factories seep into land and water and eventually contaminate soil, causing a public health risk. Arsenic from older pesticides remains in the soil of fruit tree orchards long after they have been sprayed.
Mental problems, liver and kidney damage and nerve disorders result from over-exposure to lead, cadmium and arsenic. Chronic, long-term exposure is more dangerous than short-term exposure. Other heavy metals found in contaminated soils include copper, mercury, selenium and zinc. In normal, healthy soil these metals are found in lower levels that are not a health risk.
Toxic levels of heavy metal are absorbed by the smallest microorganisms at the bottom of the food web. Contaminants are then absorbed into crops or into the sensitive organs of wildlife that feed on the soil. Heavy metals can be passed into earthworms and then eaten by birds and small reptiles. Lead in bird’s blood can result in reduced weight gain, reduced organ development and inability to maintain metabolic functions.
“Preventing heavy metal pollution is critical because cleaning contaminated soils is extremely expensive and difficult,” reports the USDA National Resources Conservation Service. The most effective method is management of the contaminated soil to immobilize the metal and break the cycle of plant uptake. Plants such as prairie grass transmute petroleum-based chemicals. Hybrid poplar trees remove TNT, nitrates and pesticides.
Home Garden Solutions
Compost has been found to transmute some heavy metal soil contamination, according to the Environmental Protection Agency. Compost has billions of beneficial bacteria and fungi that digest the toxic metals and change them into harmless substances. It also binds heavy metals to its particles, preventing them from leaching out into groundwater supplies. Home composting is an important part of cleaning up the environment and returning the earth to natural productivity.