Mining metals has been a crucial activity since the
beginning of the Industrial Revolution; it has supplied countries with bullets,
supplies, and utensils for two world wars and has renovated our transportation systems.
All of the processes, such as crushing, grinding, washing, smelting, etc.,
result in significant volumes of waste being deposited in the soil, water, and
air surrounding the mining site. It is estimated that per year the median
values of worldwide metal deposits for Cd, Cu, Pb, and Zn are 22, 954, 796, and
1372 10^6 kg (Sheoran 2011). Mining sites can be found
in many locations, including Albania, Bulgaria, Finland, Spain, Canada, and the
United States of America. Most metals, like Copper, remain near the mining site
but can be found up to 33 km away. Others, such as Arsenic may travel longer
distances due to its “atmospheric residence time” (Yoon et al. 2012). The
vegetation and animal life that surround mining areas has been drastically
effected by the toxic metal pollution; loss of biodiversity is expected near
these areas.
However,
there has been significant research that shows copper tolerance evolving in
plant populations exposed to aerially borne waste from mines. Copper metal is
normally toxic to plants in low concentration and thus, has resulted in changes
to their genetic structure. A metal refining industry in SW Lancashire emits
dust particles of copper into the surrounding environment resulting in soil copper
levels of up to 4,000 ppm (Nature 1972). While in some places the vegetation
has been completely destroyed, the grassland that does exist includes Agrostis stolonifera and Agrostis tenuis. The observed structures
of A. stolonifera in the areas surrounding
the mine are extremely different depending on the ground age. Older grassland
in highly contaminated areas has a continuous cover despite the high metal
levels. In lawns replaced within the past 10 years there is serious
contamination yet no plant life (Nature 1972). It appears that the new plants that were
introduced into the new lawns could not handle the high levels of metal toxins.
In contrast, the older grassland had selected towards copper-tolerant individuals
and had disposed of weak genotypes, or non-tolerant/slightly tolerant
genotypes. This is a clear example of recent evolution and natural selection of
plant species due to the pollutant of aerially borne metals.
References:
Kabir, Ehsanul, Sharmila Ray, Ki-Hyun Kim, Hye-On
Yoon, Eui-Chan Jeon, Yoon Shin Kim, Yong-Sung Cho, Seong-Taek Yun, and Richard
J. C. Brown. "Current Status of Trace Metal Pollution in Soils Affected by
Industrial Activities."National Center for Biotechnology Information.
U.S. National Library of Medicine, 03 May 2012. Web. 19 Feb. 2013.
<http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3356731/>.
Sheoran, V., P. Poonia, and S. K. Trivedi.
"Metal Pollution in Soil and Plants Near Copper Mining Site." International
Journal of Geology, Earth and Environmental Sciences 1.1 (2011):
27-34. Web. 18 Feb. 2013.
<http://www.cibtech.org/J%20GEOLOGY%20EARTH%20ENVIRONMENT/PUBLICATIONS/2011/Vol%201%20No.%201/016-4-JGEE-SHEORAN.pdf>.
Wu, Lin. "Aerial Pollution and the Rapid
Evolution of Copper Tolerance." Nature 238 (1972):
167-69. Nature. Web. 17 Feb. 2013.
<http://www.nature.com/nature/journal/v238/n5360/pdf/238167a0.pdf>.
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Have researchers identified which mutations confer high copper tolerance? Do you think similar mutations could confer tolerance to other toxic metals such as arsenic or mercury?
ReplyDeleteYet another example of how we humans are changing our environment and mother nature finds some way to adapt!
ReplyDeleteThe plants are changing genetically in certain ways, one way is the shape/size of their root structure is drastically different from plants that are not exposed to such high levels of copper. While I researched mainly on copper mines, I am not sure how arsenic or mercury have affected plants in surrounding areas; I would hope some plants would have been able to evolve as well and adapt to the toxic levels.
ReplyDeleteI wonder if these highly tolerant plant species have been able to overtake some of the weaker varieties even in areas with lower metal contamination? It seems sort of like the effect an invasive species with high tolerance can have but instead of an outside species it is just a highly adaptive native species.
ReplyDeleteAre A. stolonifera sensitive to any particular copper isotopes or forms (maybe in compound form) more so than another? If so, mining refineries can perhaps minimize the negative effects on the environment through modification of outputs.
ReplyDeleteDo you happen to know if there were any other species that reacted in a similar way, possibly including animals? It would be interesting to see if there were parallels in evolution among species, or if certain species were more sensitive/adaptive to the changing conditions.
ReplyDeleteVery interesting stuff. That Nature article was published over 40 years ago, though. I wonder what new research has been conducted on this topic since then.
ReplyDeleteStella mentioned arsenic's potential effect on plants-- I recently learned that rice is actually really good at taking up arsenic from the soil. It would be nice if rice crops could be grown near projects that produce a lot of arsenic in order to keep arsenic levels in the soil low... but then that would mean that all of that arsenic would end up in our rice crispies for breakfast, and that wouldn't be ideal!
This article is very interesting. Due to its age, however, I also wonder what new research has been done and if there has been any innovations to prevent vegetative depletion near mining sites.
ReplyDeleteI don't know if this would work or not, but what came to mind while reading this post was the possibility of maybe selectively breeding (artificially selecting) this copper tolerant population with other non-tolerant variations of the species in order to allow its growth near mining sites. This may also be applicable to other species of vegetation. For example, if you were to plant an initial population and have a couple of individuals survive due to random beneficial mutations in their genome, you may be able to "artificially" create populations of vegetation that are unaffected by mining metals. Of course, the ideal solution would be to limit to pollution but this wouldn't be a terrible alternative.
The idea of metals polluting the environment and altering evolution was pretty interesting. I wonder if there are examples of plants evolving to have a higher resistance to metals like copper before mining became widespread. Natural events could bring well-buried metals to the surface, where they can contaminate the environment. A study could compare the effects of man-made pollution with natural contamination, which could tell us something about how humans have helped direct evolution.
ReplyDelete