On November 12th, Kathy High and Intern Sierra Sukay went to the Sanctuary to meet with Oliver Kellhammer and assist him in collecting soil samples from the L-lot. Oliver, in conjunction with the Sanctuary, started bioremediations efforts in the L-lot this summer. In the back portion of the L-lot where the soil suffers from high lead concentration, was separated into three sections. One section has been covered with mulch and a fungi called mycelium, which has been used to reduce the amount of lead and other pollutants in the soil in sites around the world. Buckwheat was planted in the second section. Buckwheat is a very efficient tool for bioremediation because it grows quickly while “sucking” up the lead in the soil and storing it in the plants tissue. The third section is a control; it contains a collection of weeds “native” to Troy.
This Wednesday they collected soil from spots that soil had been collected from before the bioremediation efforts began in order to track the progress of the soil quality. The soil will be tested again in late April or early May and with the data from the soil tests, the Sanctuary will be able to see how the spring growing season affects the soil quality. Using the results that come back from the spring soil tests, the Sanctuary will decide how to best remove the lead from the soil. They also took samples of mycelium tissue and the buckwheat plants. The buckwheat in the L-lot has already died due to the frost and the Sanctuary will soon remove all the dead biomass. Once the buckwheat plants “suck” up the lead, the lead remains in the plant, so if the plants did “suck” up lead in the soil the Sanctuary will have to dispose of them properly. The Sanctuary will decide what to do with the buckwheat once the test results have come back on the concentration of lead in a sample buckwheat plant that was taken at the same time as the soil samples.
Oliver holding a sample of mycelium.
Oliver digging a soil sample in the section containing buckwheat.
Oliver digging a soil sample in the section containing mycelium.
Click here to read an Intern’s earlier blog post on the Sanctuary website explaining bioremediation and testing the garden near the carriage house. Below is an excerpt that explains bioremediation and phytoextraction.
What is bioremediation and phytoextraction?
It is hazardous to grow plants for human consumption in soil that contains too much lead. If there is lead in soil that you plan to plant a garden, you will first need to take steps to remove the lead from the soil. Currently, the Sanctuary is doing this through a form of bioremediation called phytoextraction.
Phytoextraction involves using plants to remove contaminants, such as lead, from the soil. Phytoextraction is better for the environment than traditional methods, which are usually just digging up the contaminated soil and transporting it to a hazardous waste facility which is costly and damaging to the environment. Some plants, such as the sunflower and Indian mustard, absorb and store lead from the soil if the plants are cultivated using specific agronomic practices. After the plants have grown and absorbed the lead, they are harvested and disposed of as hazardous waste. If you would like to learn more phytoextraction click here!
The diagram above illustrates the phytoextraction process and was taken from http://www.epa.gov/region1/leadsafe/pdf/appendixC.pdf.