• Monday, Sep 24, 2018
  • Last Update : 09:38 pm

Chemical catastrophe?

  • Published at 03:34 pm September 6th, 2018
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The Impact of acid rain on Norway spruce trees in Poland

We need to fully consider the environmental risks that Rampal may have on the Sundarbans

With Rampal set to go ahead despite public opposition, the impacts of the project require serious consideration by those monitoring and evaluating the environmental effects of the project. Hopefully, the right controls are in place to ensure that if the project does go ahead, the impact on the Sundarbans forest, located 14 km south of the project site, remains minimal. It is essential that this majestic national landmark maintains its richness and diversity within its ecosystem, and does not face the same challenges other forests, like the Boreal (Taiga) forests have in the Northern hemisphere. 

While trying to minimize bias, one cannot consider the serious possibility of generating acid rain from the power plant emissions. Acid rain is causing massive problems for the Taiga forests, which expands all the way from Asia to North America, extending from Siberia to Alaska. Acid rain is damaging these forests, and perhaps we could learn lessons from there and implement a stellar environmental monitoring strategy as "Climate Champions" and also consider remedial options in the process.

Exhaust gases and acid rain

Certain aspects of the project still remain unclear. For example, scrutinizing the chemical characteristics and composition of the source of the coal may present important long term effects on vegetation and habitat of the rich and diverse ecosystem of the Sundarbans. Depending on type (or rank) of coal used in the operation of the power plant and its rank, sulphur may be present in high or low concentrations. Sulphur is naturally occurring in the environment and is trapped over time in coals, and typically coals that are lower in rank possess higher concentrations of sulphur containing compounds. 

Sulphur compounds present in the coal when combusted will form sulphur oxides transported with the exhaust gases. Sulphur dioxide is a serious pollutant, a foul smelling gas similar to that of rotten eggs. It reacts with atmospheric oxygen to form sulphur trioxide and combines with water to form sulphuric acid. 

The serious risk of sulphur containing emissions

The formation of this acid and subsequent deposition back on the ground during heavy rainfall presents potentially detrimental effects in a rich mangrove environment including on plant life, subsequently impacting the terrestrial food chain in the mangrove ecosystem beginning with the herbivorous animals in the area. In addition, heavy winds and tides can spread acidic solutions over hundreds of miles. The potential for dispersion is high, particularly in a cyclone prone area like the Sundarbans, where winds over approximately 200km/h during cyclone Sidr in 2007 caused severe damage to about a quarter of the entire mangrove forest. 

It is estimated that sulphur containing emissions are responsible for killing one million people annually. The sourcing of the coal must be considered and ensuring low-sulphur coal as a priority should be considered for those looking to mitigate the effects of this power plant on the ecosystem. Otherwise, options are available to reduce the concentration of sulphur in the exhaust gases, such as seawater scrubbing treatment prior to release, which while expensive, is able to remove sulphur from the air and discharges directly into the ocean. Sulphur discharge in the ocean has shown to pose negligible impacts while its potential to cause damage is significantly greater in a vapour form.

Generation and fall of acid rain lowers pH of the aquatic bodies, negatively impacting fish populations. Aquatic life is seriously impacted when the pH falls below 5.0, and most of the fish are expected to die at a pH of less than 4.5. Additionally, sulphur dioxide is a lung irritant, and high concentrations of it will cause respiratory problems in animals. Combustion of coals will release other exhaust gases, many of which contribute to global warming including hydrocarbons, carbon monoxide and nitogen oxides. 

A dieback zone in a cyclone area could make things even worse

Nitrogen oxides may also react photochemically with hydrocarbons and oxygen to produce nitric acid, which is toxic to all growing organisms and will increase the likelihood of acid rain as well. With a higher acidic concentration in aquatic solutions within the ecosystem, magnesium, aluminum and other heavy metals are able to chemically mobilize out of the soil and flow into water bodies. In worst case scenarios, dead zones known as forest dieback may appear where acids strip vital nutrients from the soil and trees rapidly lose health and die over time due to the lowering of soil quality over time. 

Formation of a dieback zone in a cyclone prone area may present less buffering during cyclones and create harsher living conditions for people in the area. 

The Sundarbans is a national symbol for Bangladeshis, and a UNESCO World Heritage Site, an area rich and diverse in many unique biological species found nowhere else in the world. We cannot claim be victims of climate change and subsequently make decisions to construct a coal power plant within the vicinity of one of our many fertile ecosystems and not seriously consider long-term impacts of these decisions. While I understand the urgent need for a rapidly industrializing country and that having a tall stack (approximately 275m) may reduce immediate short term impacts associated with the power plant's emissions, my fundamental understanding of the hydrological cycle is that gravity and rain will definitely bring the exhaust driven particulates back to terrestrial land, in lieu with the cliched saying that "what goes up, must come down". 

It is absolutely essential that we preserve this beautiful local landmark so that future generations, our children and grandchildren, can witness and are able to enjoy the same natural beauty of the Sundarbans as we have, including the lush flora and fauna, and the wide range of rare animal species which may struggle in the long-term to withstand the effects of the power plant emissions.

The author is a Geological Engineering graduate from the University of British Columbia in Vancouver, Canada. He has been working in the field of engineering consulting for over seven years.