Heavy Metal Remediation

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By adding phosphorous to the area, it will bind to the lead and forms pyromorphite crystals. This is a form of lead which is non-toxic and not bioavailable to plants. Some good sources of phosphorous are fish bones, bone meal (calcium phosphate), bat guano and chicken manure. In order to form the pyromorphite, we must lower the soil pH first to make the lead more mobile. Adding organic sulfur, pine needles, peat moss, sawdust, leaf mold and/or coffee grounds to soil will increase acidity. Adding a soluble form of phosphorous, and the two should combine into the more inert and less bioavailable pyromorphite.

Regular testing of the soil is needed to see if pyromorphite is indeed being formed. It could take several weeks for this reaction to occur. If it does not, then adjustments with different sources of phosphorous and the pH will be introduced until we find the right match.

By incorporating hyperaccumulating plants into the surrounding area, natural extraction of heavy metals from the soil can be achieved.

Planting multiple rotations of lead-accumulating plants and making sure to take the proper precautions with their testing and disposal, will eliminate metals from leaching into the surrounding environment. Plants that hyperaccumulate heavy metals can be disposed of properly and safely.

The more rotations of phytoextractors we use, the more lead we will withdraw, as long as we keep the soil at an optimal acidity for uptake. Some common plants that have been experimented with are: Alpine Pennycress (Thlaspi caerulescens), Sunflower (Helianthus annuus), Brown Mustard (Brassica juncea), Geranium (Pelagrium spp), Corn (Zea mays), Vetivergrass (Vetiveria zizanioides), and Spinach.