## 4 Conclusions  
The use of marginal lands for generating biofuel is being increasingly explored in recent years. Mine soils are marginal, due to their sandy texture, lack of nutrients and elevated heavy metal content. Studies on growing cool-season grasses such as switchgrass has been reported in reclaimed surface mining sites. However, there are only a handful of studies on the use of short-rotation oil seed crops that can perform the dual role of providing a vegetative cover and generate income in the form of biofuel. Camelina and field pennycress are cold-tolerant and have the potential to be used as winter cover to reduce soil erosion and metal leaching on the shores of Torch Lake. In our Phase I column study, we found that 10% compost amendment to stamp sand was optimum in promoting plant growth without substantially increasing Cu leaching from stamp sand. There was very little uptake of Cu by camelina and field pennycress. Cu concentration in camelina and field pennycress was highest in leaves, but lowest in seeds and pods. Cu concentration in the leachates was low. The turbidity measurements in the leachates could not be used as a proxy for estimating stamp sand erosion. Hence, we performed a Phase II panel study, where the measurement of turbidity and total suspended solids in the surface runoff was used to measure stamp sand erosion. In the greenhouse panel study, camelina grown on contaminated stamp sands amended with compost significantly reduced stamp sand erosion in the surface runoff, as compared to the control panel with no plants. Cu concentration also decreased significantly in surface runoff from the camelina panel, as compared to control. There was a negligible amount of Cu in the camelina seeds.  
Figure 5: Fatty acid composition (wt. % of extracted oil) of camelina seeds. Data are expressed as mean (\(n=2\)) \(\pm\) standard deviation.  
Camelina seeds contained 20 and 22.7% oil and protein, respectively. The fatty acid composition of amelina seeds did not differ from the previous studies performed on uncontaminated agricultural soils. Our study shows that amelina grown on contaminated stamp sand amended with compost not only significantly reduced stamp sand erosion but also can also be used commercially for generating biodiesel. Further field-scale studies are necessary to elucidate this phytomanagement strategy. If successful, this model would be applicable to other marginal lands for their restoration/ stabilization and production of biofuel, providing economic and environmental benefits.  
Conceptualization, D.S. and R.D.; methodology, V.S. and D.S.; investigation and analysis: V.S.; writing--original draft preparation, V.S.; writing--review and editing, R.D. and D.S.; supervision and project administration: D.S. All authors have read and agreed to the published version of the manuscript.  
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.  
The authors thank [PERSON] and [PERSON] for their help in the collection of stamp sands. The authors also thank [PERSON] for her help in the greenhouse panel study at MTU. Thanks are also due toward USDA-NRCS for providing the seeds of amelina and field pennycress for the greenhouse column and panel studies.  
The authors declare no conflict of interest.