By Tanya Silverman
The thought of rain, depending on the individual, may seem pleasant or unpleasant. The thought of acid rain, however, likely triggers an immediate reaction of unpleasantness to most.
Beyond just a thought, though, the actual unpleasantness that comes with acid rainfall is not only in its immediate effects, but from ensuing ones that unfold.
Several naturally occurring events, like erupting volcanoes or rotting vegetation, can cause the release of chemicals into the atmosphere that form acid rain. Nevertheless, human activity is mainly responsible for the phenomenon, especially from the burning of fossil fuels in factories, power plants, and automobiles.
Formerly, acid rain was considered a local environmental issue. However, in the 1950s, it became realized that industrial air pollution would often float far away. For example, the emissions from fossil fuel burned in the UK and Northern Europe would drift to Scandinavia.
When the acid rain falls from the upper atmosphere to the Earth’s surface, chemical changes can result. Acid rain entering lakes and streams can alter the pH level, causing fish populations to decline. Acidic water is notably dangerous to game fish like bass and trout.
On the land, acid rainfall can disturb the chemical compositions of soils. Certain kinds do contain buffering capabilities that neutralize the acidic compounds, such as those in Nebraska or Indiana. However, the soils in the Adirondack Mountains of New York State suffered from acidification because they are not naturally well buffered.
The state of forests’ health is additionally vulnerable to acid rain. While the precipitation does not commonly kill trees directly, leaf and branch damage can occur. Trees may have problems photosynthesizing if the waxy layer of leaves gets worn from the acid rain.
Additionally, soils that soak up acids may end up with increased levels of aluminum, which can harm trees. In the Adirondacks, forests that grew in higher elevations were detrimentally affected because they were surrounded by acidic clouds and fog coupled with less healthy soils.
Photo by Tanya Silverman.
Certain environmental conditions have improved more recently, though. Researchers who examined lakes around the New England and Adirondacks region discovered that there were higher rates of recovery from acid rain between 2002 to 2010 (as opposed to the levels during the 1980s and 1990s). The improvement is due in part from more stringent emissions regulations the US government enacted during the 1990s in accordance with the Clean Air Act.
Despite the human action and natural reaction, a long-term effect still dawns upon many Canadian lakes due to acid rain: jellification. Lots of little Holopedium glacialis, jelly-clad invertebrates, have taken to habituating lake water with reduced calcium levels. Decades ago, calcium-rich plankton known as Daphnia thrived in these lakes, but their populations have largely disintegrated due to the acidification and jellification linked to air pollution and logging.
A research team investigated the jellification process and concluded that the gelatinous Holopedium population doubled from the mid 1980s to mid 2000s in many Ontario lakes.
Study co-author Dr. Andrew Tanentzap tells BTR about the ongoing jellification process.
“Acid rain is very effective when it lands on soil in displacing the calcium,” he explains. This is because of the “depleted calcium levels from soil [so] there’s less calcium naturally exported into the water.”
The entailing acidic aquatic environment means the Daphnia plankton cannot access the amount of calcium they require to survive. When they lack said nutrients, it makes it harder for them to reproduce and consume food, not to mention becoming more susceptible to predators.
So, enter the jelly–or Holopedium. These jelly plankton are competitors to the Daphnia, and, since they don’t utilize as much calcium, thrive in the Ontario lakes that contain depleted levels of the chemical. Tanentzap elaborates that the jelly coating acts as a big “bubble” to protect from predators.
Tanentzap and the team of researchers studied the environmental results from implemented pollution control. They determined such action was successful at reducing the acid deposits that existed in the landscapes.
Throughout the lakes, Tanentzap explains, “the chemistry recovered, the pH is recovered, and we can reverse these impacts.” However, judging by the present jellification, “the biological impacts have still yet not fully recovered” in many of the ecosystems.
“The buildup of calcium in soils is something that’s played out for [about] 20,000 years,” remarks Tanentzap, “so you can’t really go about replenishing calcium in soils so easily.”
Issues might not just stop there. Excess jelly in lakes might cause clogging to drinking water filtration devices. The Ontario lakes’ food chain also might face problems. If fish cannot eat calcium-rich Daphnia, their nutrient intake is reduced, and that health issue may transfer to human consumption.
Perhaps the phrase “acid rain” is not as commonly heard in the current state of affairs, however, we continue to see the consequences of air pollution play their course.