On the island of Luzon in the Philippines, a nickel hyperaccumulating plant named Rinorea Niccolifera was discovered by botanists from the University of the Philippines. The R. Niccolifera was found in small populations in areas with high concentrations of metals in the soil. Hyperaccumulator plant species are unique because of their ability to collect metal and metalloids at toxic concentrations without negative consequences to their physiology. While nickel hyperaccumulator species are rare to begin with, what makes the Rinorea Niccolifera special is its ability to accumulate greater than 18,000 µg g-1 of nickel. Other nickel hyperaccumulator species in this genus could only manage to collect 1800-17,500 µg g-1 of nickel. The deposits of nickel in their roots or leaf tissues is said to deter herbivores from eating the plant.
This ability to absorb metal has many thinking about the commercial potential of hyperaccumulator plants in eco-friendly technologies that aim to tackle the problem of polluted soils. This includes phytoremediation, which uses metal absorbing plants for the restoration of polluted soils, and phytomining, which aims to extract metals for commercial purposes. Unfortunately, the Rinorea Niccolifera is classified as endangered as its current known habitat, which is less than 500km2, is victim to severe fragmentation and other human activity and is predicted to decline.
One example of an attempt at photomining took place in Oregon. This article goes into more detail about the disastrous events that took place in Oregon’s Illinois valley which explains how the nickel hyperaccumulating plant called Yellow tuft alyssum attained invasive species status.
To summarize, a pilot study in 1997 investigated whether photomining could truly be a commercially viable method of extracting nickel. A research team headed by Richard Roseberg, and funded by Viridian, planted Yellow tuft alyssum in Oregon’s Illinois valley in a very controlled setting. Roseberg and his team carefully monitored the experimental site for years and concluded that it was unlikely the plant would become invasive as long as his proposed protocol was followed. As the alyssum stores the nickel in its leaves, Roseberg’s protocol stressed that the plant be mowed before it bloomed as this reduces the risk of seed dispersal. The plants were then burned and the nickel was recovered from the ashes. However, when the study produced promising results, Viridian cut off funding for the research, and began to replicate the experiment on a larger scale using their own workers. Long story short, in spite of warnings from Roseberg, Viridian workers did not carefully follow the protocol and sometimes mowed the plant after bloom and did not take care in washing their equipment which ultimately increased the risk of seed dispersal. Ultimately, Yellow tuft alyssum began spreading and in 2009 was declared an invasive species and its removal has been nothing short of costly. Eventually Viridian gave up on the photomining experiment as Oregon’s soil did not have as much nickel as they thought.
Whoops, I guess. Let’s all share a collective facepalm.