By: Dana Sackett
When most people think of pollution caused by coal-burning power plants, a tall smokestack spewing a large cloud of soot and fumes is the first image that comes to mind. This image represents the air pollution caused by coal combustion and is perhaps the most obvious. In actuality, there are many less obvious forms of pollution that are created by coal-burning. These other forms of pollution occur through every stage of the process: coal-mining, coal transport, chemicals used to clean coal, coal combustion, and in the storage of the resultant toxic ash from coal combustion. The latter has been in the news of late, demonstrating the devastating effects that result from these sources of pollution, especially when they go unchecked.
In 2008, a coal-ash storage pond wall broke at the Tennessee Valley Authority creating the largest coal-ash spill in US history, with over 4.1 million cubic meters of ash spilling into the Emory River and its tributaries. This spill caused elevated mercury, arsenic, selenium and radioactivity in sediments at and downstream of the spill site. These chemicals along with other trace metals (e.g., lead, chromium) are commonly responsible for the problems seen in aquatic ecosystems following coal-ash spills.
Because, we have already discussed the affects of selenium in aquatic ecosystems in an article previously published by The Fisheries Blog (Trout, a canary in the phosphate mine), here we will focus on how some of the other contaminants may affect fish in the areas impacted by these spills.
Arsenic is notoriously poisonous to nearly all life. In fish, it can cause toxic effects in the liver and immune system as well as affect reproduction and development ultimately influencing population levels. Mercury in coal-ash can be methylated in aquatic systems forming methylmercury, a neurotoxic form that can enter food webs (see Mercury in fish, what should I eat?). This methylation process can be exacerbated by other contaminants in coal-ash causing a hotspot of highly contaminated fish that may last for decades. Coal also contains uranium, thorium and radium, radioactive elements that concentrate in coal-ash after coal is burned. This radioactivity can be highly carcinogenic and cause genetic mutations.
The coal-ash spill in Tennessee was not the first. In many states coal-ash releases into the environment have caused fish kills, reproductive failures and population declines. People, on the other hand, face being exposed to the airborne carcinogenic coal-ash released during a spill and the loss of aquatic resources for drinking, food and recreation. In fact, just this past month in North Carolina a pipe running under a coal-ash pond collapsed releasing toxic ash up to 70 miles downstream in the Dan River.
As with most contaminant-related spills, politics lie at the center of stopping future disasters. However, following the 2008 spill in Tennessee it seemed the US Environmental Protection Agency and others were on the brink of proposing legislation to prevent future spills but those efforts were postponed explaining more time was needed. While North Carolina is working on legislation that will prevent future spills of this nature, many are suggesting that these steps should have been taken years ago.
Some have also suggested that the reason for the delay in legislation to protect aquatic resources from coal-ash ponds in North Carolina may be that regulators have become “cozy” with Duke Energy, the ones responsible for the spill. However, with another spill occurring just days ago contaminating more of the Dan River, the pressure is on for North Carolina and others to prevent these spills from contaminating more waterways and poisoning our aquatic resources.
References and other resources:
Gillespie A. 2010. Coal-ash regulations delayed. Frontiers in Ecology and the Environment.
Hatcher CO, Ogawa RE, Poe TP, French III JRP. 1992. Trace elements in lake sediment, macrozoobenthos, and fish near a coal ash disposal basin. Journal of Freshwater Ecology 7:257-269.
Otter RR, Bailey FC, Fortner AM, Adams SM. 2012. Trophic status and metal bioaccumulation differences in multiple fish species exposed to coal ash associated metals. Ecotoxicology and Environmental Safety 85:30-36.
Papastefanou C. 2010. Escaping radioactivity from coal-fired power plants (CPPs) due to coal burning and the associated hazards: a review. Journal of Environmental Radioactivity 101:191-200.
Ruhl L, Vengosh A, Dwyer GS, Hsu-Kim H, Deonarine A, Bergin M, Kravchenko J. 2009. Survey of the potential environmental and health impacts in the immediate aftermath of the coal ash spill in Kingston, Tennessee. Environ Sci Technol 43:6326-6333.