The phytostabilization potential of native plants: a survey of endemic plants and microbes across the historic Harshaw Mining District, Southern Arizona
Abstract
Mining and exploration of mineralized zones is essential for economic growth; however, the legacy of mining operations can remain for decades to centuries if not treated, posing risks to human and animal health due to fugitive dispersal of metal(loid) laden dust and water. Phytostabilization (establishment of vegetative cover on unconsolidated to semi-consolidated piles of tailings/wasterock overburden) is a method of reclamation which can mitigate potential harmful exposures and result in beneficial ecosystem services. The use of endemic plants is key to the success of phytostabilization, because endemics are adapted to the conditions prevailing in local mine sites, such as low organic matter and nutrient content, high metal concentrations, and acidic pH. To this end, we evaluated the phytostabilization potential of endemic plant populations growing at two unmined mineralized sites and on metallic wastes at two historic mine operations within the Harshaw Mining District in southern Arizona. Although vegetation was sparse across all investigated sites, we identified four perennial grasses and three shrub species growing on heavy metal laden tailings piles and quantified total metals in bulk and rhizosphere soil, along with above and below ground plant material. We also used high-throughput DNA sequencing to characterize the soil microbial community (i.e. bacteria & fungi) associated with each plant species and mine or soil type to determine the effect of the plant microbiome on metals accumulation in plants. On mined sites, we observed that grasses accumulated more Co & Cu in leaf tissues than shrubs, but other metals of concern (e.g. Pb, Zn, and Ag) did not accumulate in any examined above-ground tissues. One grass species, Bouteloua curtipendula, consistently had both high soil concentrations factors (i.e. metals concentrated in root-associated soils) and low metals accumulation factors (i.e. metals translocated to above-ground tissues). Microbial populations varied significantly according to both mine type and plant species. Together these results indicate that plants endemic to mined areas are viable options for future phytostabilization efforts, and that B. curtipendula represents a strong candidate for phytostabilization due to its broad geographic range and low metals translocation factor.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGH33C1204L
- Keywords:
-
- 1065 Major and trace element geochemistry;
- GEOCHEMISTRY;
- 0210 Coal geology;
- GEOHEALTH;
- 0215 Economic geology;
- GEOHEALTH;
- 1834 Human impacts;
- HYDROLOGY