Black Sea and pollution
The Black Sea is a large inland body of water bordered by six Eurasian countries: Turkey, Bulgaria, Romania, Ukraine, Russia, and Georgia. It has a distinct ecosystem that has been severely impacted by pollution, overfishing, and the introduction of nonnative species, which have endangered its biodiversity. The lower depths of the Black Sea are nearly lifeless due to a lack of dissolved oxygen, creating one of the world’s largest "dead zones," while the upper regions suffer from eutrophication and declining fish populations. Historically, significant rivers such as the Danube and Dnieper contribute to the sea’s nutrient load, worsening the pollution crisis.
In response to these environmental challenges, international efforts have been initiated, including the Convention for the Protection of the Black Sea Against Pollution and ecosystem recovery projects. Despite some signs of recovery due to reduced economic activity in the region, ongoing concerns remain, particularly in the context of the ongoing conflict in Ukraine, which has led to increased pollution and environmental degradation. Future prospects for the Black Sea may involve utilizing its deposits of ammonia, methane, and hydrogen sulfide for energy production, provided that effective pollution control measures are implemented.
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Black Sea and pollution
IDENTIFICATION: Large inland sea bounded by the Eurasian nations of Turkey, Bulgaria, Romania, Ukraine, Russia, and Georgia
Because of a lack of oxygen, the lower levels of the Black Sea are virtually lifeless, and the abundant life of the sea’s upper levels has been gravely endangered by pollution, overharvesting, and the introduction of destructive nonnative species. Progress has been made in addressing these problems, however, as the result of dedicated international efforts.
It is believed that the Black Sea was formed when the rising waters of the Mediterranean Sea swamped a freshwater lake about 7,500 years ago. The sea has a surface area of approximately 448,000 square kilometers (173,000 square miles) and reaches a maximum depth of approximately 2,200 meters (7,200 feet). Five important rivers—the Kuban, Don, Dnieper, Dniester, and Danube—flow into it, and in turn its brackish flows out into the Mediterranean through the Bosporus strait, the Sea of Marmara, and the Dardanelles strait. Colder, saltier water flows in beneath this current from the Mediterranean to the Black Sea’s depths. Within the Black Sea itself, circulation between the two layers is poor.
Because the Black Sea’s lower levels do not contain enough dissolved oxygen to enable bacteria to decompose the matter carried into the sea by the rivers, the water has grown increasingly eutrophied (saturated with nutrients) and anoxic (oxygen-depleted), creating one of the largest “dead zones” of virtually lifeless water on the planet. Bacteria have evolved under these conditions, to react with naturally occurring sulfate ions in the seawater to produce the world’s largest of deadly hydrogen sulfide gas. Significant deposits of ammonia and methane are also present.
Fish and shellfish such as anchovy, mullet, tuna, mussels, and oysters were once found in abundance in the upper levels of the Black Sea, but in the latter decades of the twentieth century their numbers fell dramatically. This decline was caused in part by overfishing, but from agriculture, industry, and shipping (particularly of crude oil) played a more important role. Cultural (human-caused) eutrophication of the sea’s shallower waters contributed to a precipitous decline in fields of Cystoseira and Phyllophora algae, species essential to the survival of the food chain. In 1982 the alien carnivorous sea jellyMnemiopsis leidyi was found for the first time in the Black Sea, and within a few years its rapidly growing numbers had destroyed a large proportion of the native species’ eggs and larvae. During the 1990s radioactive substances resulting from nuclear power generation and the Chernobyl nuclear accident of 1986 began to enter the Black Sea as well.
By the end of the twentieth century, however, the Black Sea’s began to show a partial recovery owing to the region’s economic slowdown and a resulting decrease in pollution. The sea had been recognized as a major environmental disaster area, and the six nations on its shores had drafted the Convention for the Protection of the Black Sea Against Pollution in 1992. This convention was succeeded by a number of other international efforts focusing on specific environmental problems, including the Black Sea Ecosystem Recovery Project of 2004–7, which dealt primarily with eutrophication and hazardous waste. Nonetheless, as of a 2016 survey, the Black Sea contained 145 different pollutants and the hydrogen sulfide layer had expanded. A 2023 study suggested that despite the slight decline in population in this area, the pollution will continue to spread as the harmful substances originating in the lake enter the nearby rivers. The study also analyzed multiple sources and concluded that with the likely economic growth in the area surrounding the Black Sea, there is potential for advanced pollution control systems including expanded sewage systems and better crop irrigation. In addition, Russia’s war on Ukraine that began in 2022 further increased concerned about the environmental status of the Black Sea. Many of the natural protected areas along the Ukrainian coast were under Russian occupation as of 2024, and protection efforts were no longer being maintained. The war had also increased pollution into the sea and destroyed coastal infrastructure in many areas.
In the future the Black Sea’s deposits of ammonia and methane may be utilized to produce fertilizer and to generate electricity, and its hydrogen sulfide may be tapped as a source of hydrogen gas for fuel. The extraction technologies involved are expected to have the added advantage of returning purified water to the sea.
Bibliography
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Strokal, Maryna, et al. "The Future of the Black Sea: More Pollution in over Half of the Rivers." Ambio, vol. 52, 8 Sept. 2023, pp. 339-356, doi.org/10.1007/s13280-022-01780-6. Accessed 16 July 2024.