Field Pennycress (Thlaspi arvense) and Camelina (Camelina sativa) Have Potential for Sustainable Stabilization of Copper Contaminated Soils: A Greenhouse Feasibility Study.

Extensive mining activities during the late 19th and early 20th centuries in the Upper Peninsula, Michigan have resulted in a number of contaminated sites with mine tailings. Several million metric tons of mine tailings were generated during the peak of Cu mining activities in this region. These tailings are called “stamp sands” because they were generated by crushing native Cu containing rocks, by a process known as stamping. The stamp sands were discharged into Lake Superior, other interior lakes and their shorelines, converting these areas into vast, fallow lands. The Cu contaminated stamp sands are being eroded back into the lakes, severely affecting the benthic community. Our objective is to grow cold-tolerant oil seed crops camelina (Camelina sativa) and field pennycress (Thlaspi arvense) on these marginal lands, which will serve the dual purpose of producing feedstock for biofuels and also reduce the erosion of the Cu contaminated soils into the lakes. A greenhouse study is in progress using Cu contaminated stamp sands collected from two different sites; the Gay site and the Hubbell/Tamarack site in Torch Lake. A sandy soil with no contamination is used as a control. The experimental soils are slightly alkaline in nature, have very low organic matter content and are highly deficient in nutrients, especially P. The Gay and Hubbell/Tamarack site stamp sands have about 50 and 19 times higher total Cu concentration compared to the control soil respectively. Sequential extraction of the soils showed that Cu is mainly bound to the moderately oxidizable fraction. Biosolids collected from the local Portage Lake Water and Sewage Authority (PLWSA) is being used as a source of nutrients for the plants. Data obtained from these experiments will help optimize the conditions for a field study to establish oil seed crops on mining impacted stamp sands in the Upper Peninsula.