What Are Heavy Metals?
Heavy metals are a class of elements that include lead, copper, arsenic, and cadmium, and can be toxic to humans and plants if ingested in high enough quantities. Soils have often been the landing spot for heavy metals, chemicals, and wastes as byproducts of industrial and agricultural pollutants. Many of these metals are present in soils naturally, usually in small amounts, although the natural level may vary.
If you are concerned about heavy metals on your land, you should have the soil analyzed by a laboratory for heavy metal content before using it for a vegetable garden, farm site, or children’s play area. Heavy metals are more of a concern in urban areas, especially when near sites historically used for industry. Certain contaminants, when present in high amounts, can cause detrimental effects on humans, animals, and plants. With proper care and treatment, contaminated soils can be remediated and used safely.
The UNH Cooperative Extension Soil Testing Program offers a series of analyses for certain heavy metals. Our “Environmental Package” includes analysis for total cadmium, chromium, copper, nickel, lead, and zinc. We also offer individual analyses for total arsenic, mercury, molybdenum, and selenium. These analyses are done using EPA methods.
Interactions between heavy metals and soil constituents (clay, organic matter, pH, etc.) are fairly complex; therefore we suggest that you also request the standard fertility analysis and organic matter if you are concerned about contamination. This will allow us to interpret the results and suggest some approaches to minimize the risk of plant uptake.