Abstract
Anthropogenic pollution of the oceans is a global problem. There are many causes of ocean pollution. Scientists and environmental experts agree that in the last decades anthropogenic pollution of the oceans is widespread, worsening, and in most countries poorly controlled. Anthropogenic pollution arises from multiple environmental sources and crosses national boundaries. Pollutants are a complex mixture of toxic metals, plastic waste, manufactured chemicals, oil-petroleum, urban and industrial wastes, pesticides, fertilizers, pharmaceutical chemicals, agricultural runoff, and sewage. More than 80% of pollutants arises from land-based sources. Pollutants reach the oceans through rivers, runoff, atmospheric deposition and direct discharges. Plastic pollution is becoming a major threat to aquatic environments. Plastic pollution is found globally from deserts to farms, from mountaintops to the deep ocean, in tropical landfills and in Arctic snow. Reports of plastic debris in the marine environment started many years ago. Plastic pollution continues to accumulate on the ocean surface over the past 50 years. Estimates of global emissions of plastic waste to rivers, lakes, and the ocean range from 9 to 23 million metric tons per year, with a similar amount emitted. The Earth’s oceans are estimated to store 90% percent of the excess heat energy trapped in the Earth’s climate system by excess greenhouse gases (CO2, CH4) produced through anthropogenic activities. Averaged over the full depth of the ocean, the 1993–2022 heat-gain rates are approximately 0.64 to 0.83 Watts per square meter averaged over the surface of the Earth. Inevitably, increasing ocean heat content is contributing to sea level rise, ocean heat waves and coral bleaching, and melting of ocean-terminating glaciers and ice sheets around Greenland and Antarctica. In the 200-plus years since the industrial revolution (1820) began, the concentration of carbon dioxide (CO2) in the atmosphere has increased due to human actions. During this time, the pH of surface ocean waters has fallen by 0.1 pH units. This might not sound like much, but the pH scale is logarithmic, so this change represents approximately a 30% increase in acidity. The ocean absorbs about 26-30% of the carbon dioxide (CO2) and increased ocean acidification with detrimental impacts on marine and oceanic ecosystems. There are many global reports of the United Nations on world assessment programmes, including wastewater (discharges of municipal waste, treatment, etc). Ocean pollution cause eutrophication and hypoxia in coastal areas (pollution and lack of oxygen), from domestic and industrial waste and their impact on marine ecosystems is increasing in the last decades. Agriculture is another sector of the economy that contributes to water and ocean pollution. High amounts of “agrochemicals,” “organic matter,” “drug residues,” “sediments,” and “saline drainage” from agricultural lands are released into water bodies and subsequently contribute to sea and ocean pollution. This review describes the most important environmental pollution aspects for oceans and marine ecosystems.