Pollution's Impact On The Great Lakes Ecosystem

The Great Lakes, comprising Lakes Huron, Ontario, Michigan, Erie, and Superior, are the largest source of freshwater on Earth. They provide drinking water for 40 million people and support 56 million jobs. However, pollution poses a significant threat to the lakes' ecosystem and drinking water supply. Sources of pollution include industrial waste, agricultural runoff, sewage, and plastic waste. For instance, Lake Erie was heavily polluted by the 1960s due to industrial waste and agricultural runoff. Plastic pollution is also a pressing issue, with 22 million pounds of plastic entering the Great Lakes annually. These pollutants have severe ecological and human health impacts, including reduced water quality, loss of biodiversity, and increased cancer and birth defect risks.

Industrial waste and sewage

The dumping of industrial waste from factories and sewage treatment facilities is a significant source of point source pollution in the Great Lakes. This type of pollution is easier to manage compared to non-point source pollution as it can be traced back to a specific source and location. However, it still poses a significant threat to the lakes' ecosystems.

Lake Erie, in particular, has suffered from heavy industrial pollution along its shores. With a large population and sprawling farmland in its watershed, human activities have severely impacted the lake. Factories have dumped chemical pollutants into the lake and the waterways that flow into it, such as the Cuyahoga River in Cleveland, Ohio, and the Detroit River in Michigan. This has led to the death of fish and made swimming hazardous along the lake's shores.

The pollution of Lake Erie prompted governments on both sides of the border to take action. In 1960, the federal government ordered a comprehensive study of the lake, which confirmed that it was indeed dying. Cities surrounding the shoreline built sewage plants, and industries installed water filters to mitigate the damage and slow down the rate of deterioration.

While these efforts have helped, the Great Lakes continue to face the challenge of industrial waste and sewage pollution. It is crucial to address these issues to protect the lakes' ecosystems and the drinking water sources for millions of people.

Microplastics

Fibres from clothing or debris from larger pieces of plastic can contribute to microplastic pollution in waterways like the Great Lakes. This pollution can also come from "nurdles", small pieces of plastic used to produce larger plastic products. The breakdown of single-use plastics is a major contributor to microplastic pollution.

Some cities have started installing filters on storm drains and sewage systems to catch macro and microplastics before they enter the water systems. However, much of the microplastic pollution in the Great Lakes comes from airborne particles, not water runoff, making these filters a less effective protective measure. Experts say that we must use less plastic if we are to curb the flow of microplastics into the Great Lakes.

Eutrophication

The International Joint Commission (IJC) was formed by scientists, engineers, planners, and technical experts from both Canada and the United States to address the issues caused by eutrophication. Their findings confirmed that eutrophication was caused by "loadings of nutrients, particularly phosphorus from municipal sewage treatment plants and other anthropogenic sources."

In response to the findings, specific effluent standards were established in the early 1970s, and phosphorus removal was introduced in wastewater treatment plants. Additionally, the phosphorus content in laundry detergent was reduced from 30-40% to 5%. These measures successfully reduced phosphorus loading in Lake Erie and Lake Ontario by one-fifth and overall phosphorus reductions in the Upper Great Lakes by about 50%.

While these efforts have helped mitigate the issue, eutrophication remains a concern in the Great Lakes. For instance, in 2011, Lake Erie experienced an algal bloom of record-setting magnitude, impacting the lake's ecosystem and aesthetic value. This bloom was attributed to a combination of long-term trends in agricultural practices and extreme weather events, which resulted in increased phosphorus loading in the lake.

To further combat eutrophication in the Great Lakes, it is essential to continue implementing measures that reduce external loads of phosphorus and nitrogen. This includes properly treating stormwater overflow and increasing phosphorus removal efficiency in wastewater treatment plants. Additionally, addressing non-point source pollution, such as agricultural runoff, is crucial as it is often more challenging to manage than point source pollution.

Mercury and other heavy metals

In 1985, sampling at 250 stations in the St. Marys, St. Clair, and Detroit rivers and Lake St. Clair revealed widespread metal contamination of the sediments. The sediments were frequently polluted by copper, nickel, zinc, and lead, with the highest concentrations found in the Detroit River. These metals are associated with industrial activities in the region.

Mercury levels in some Great Lakes fish species are stable but increasing in others. Mercury is a critical element in the local economy, linked to the chlor-alkali industry and coal burning. It is also a byproduct of the auto-moto industry. The effects of mercury exposure on humans are unknown, but it has been linked to inhibiting the reproduction of coho salmon eggs and impacting the population of bald eagles.

Lead is another heavy metal contaminant in the Great Lakes, with a long history in the region due to its association with the auto-moto industry. While legislation and cleanup efforts have been implemented, the presence of these heavy metals in the sediment and water of the Great Lakes remains a significant environmental concern.

Acid rain

Most acid rain is caused by man-made sources, primarily emissions of sulfur dioxide and nitrogen oxides from fossil fuel combustion. In the United States, roughly two-thirds of sulfur dioxide and a quarter of nitrogen oxides come from electric power generation that relies on burning fossil fuels, such as coal. When these gases are released from power plants, prevailing winds can blow them across state and national borders, where they are deposited onto the landscape and drain into lakes.

In addition to directly impacting species, acid rain also causes toxic substances such as aluminium to be released into the water from the soil, further harming aquatic life. The fragile ecosystems of lakes, rivers, and marshes, where many different species of plants and animals depend on each other to survive, are disrupted. If a species of fish disappears, the animals that feed on it will gradually disappear too, causing a cascade of effects throughout the food web.

The effects of acid rain on the Great Lakes, which comprise the largest freshwater source on Earth, have been a cause for concern. Acid rain has contributed to the degradation of Lake Erie, which has been heavily impacted by human activities due to the large population in its basin and the presence of big cities and sprawling farmland in its watershed. While efforts have been made to mitigate the damage, such as the construction of sewage plants and the installation of water filters in surrounding cities, the long-term effects of acid rain on the Great Lakes ecosystem continue to be a challenge.

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