Crude oil is transformed into about 10 primary refined fuel types (e.g., gasoline, aviation fuel, diesel) and dozens of additional subcategories and specialized fuels (e.g., different grades of gasoline, diesel, and aviation fuel) within these major types. Natural gas is also transformed into about 10 primary fuel types (liquified natural gas, hydrogen) and many more specialized fuels (e.g., methanol, dimethyl ether).
More than 350,000 chemicals have been manufactured.1 Many of those are derived from petrochemicals—including ethylene, propylene, acetylene, benzene, and toluene, as well as natural gas constituents like methane, propane, and ethane. Petrochemicals are used to manufacture more than 6000 everyday products, from smartphones to tennis racquets.2. About 20,000 chemicals have been identified as “chemicals of concern” by the American Chemical Society due to their potential harmful health effects.3
The extraction, processing, and transportation of all these fuels and chemicals leads to accidents and disasters that release them into the air, land, rivers, lakes, and the ocean. The Office of Response and Restoration in the National Oceanic and Atmospheric Administration maintains a database of about 4600 reported incidents since 1957. That number is a significant underestimate because before the 1980s many incidents were not reported.
Accidents come in many forms: small chemical leaks from a barge moored in the Mississippi River; jet fuel leaked from a pipeline rupture by a crew digging a hole for a telephone pole; diesel fuel from a fishing vessel that ran aground; and a train derailment that released chlorine gas. Included in the database are major events such as the oil spills from the Exxon Valdez (1989) and Deepwater Horizon (2010) disasters. The latter was the largest marine oil spill in United States history.
Oil and chemical spills are highly concentrated in rivers and coastal regions for several reasons:4
Oil refineries, chemical plants, and industrial facilities are located near rivers and coasts to access water for cooling, processing, and transportation.
Rivers are key routes for transporting oil, chemicals, and other hazardous materials by barge or ship.
Coastal regions are hubs for offshore oil drilling and many underwater pipelines carrying oil and gas pass through rivers and coastal areas.
Coastal and riverine regions are often highly developed, resulting in a concentration of industrial, agricultural, and commercial activities that increase the risk of fuel and chemical spills from land-based sources.
Coastal cities with large ports have large volumes of traffic from tankers, cargo ships, and vessels transporting chemicals, making these areas vulnerable to spills from ship accidents, collisions, or improper waste disposal.
Most incident reports from NOAA have a written description with details of the event. A count of the frequency of words or terms in 3925 reports reveals an essential feature: crude oil and its derivative fuels (diesel, gasoline, fuel oil) dominate the spill database.
1 Wang, Zhanyun, Glen W. Walker, Derek C. G. Muir, and Kakuko Nagatani-Yoshida. “Toward a Global Understanding of Chemical Pollution: A First Comprehensive Analysis of National and Regional Chemical Inventories.” Environmental Science & Technology 54, no. 5 (March 3, 2020): 2575–84. https://doi.org/10.1021/acs.est.9b06379
2 U.S. Department of Energy, “Products made from oil and natural gas,” accessed September 11, 2024, https://tinyurl.com/yxt2emdj
3 Muir, Derek C. G., Gordon J. Getzinger, Matt McBride, and P. Lee Ferguson. “How Many Chemicals in Commerce Have Been Analyzed in Environmental Media? A 50 Year Bibliometric Analysis.” Environmental Science & Technology 57, no. 25 (June 27, 2023): 9119–29. https://doi.org/10.1021/acs.est.2c09353
4 This list was edited and adapted directly from the response to this query posed to ChatGPT (version 1.2024.233) on September 11, 2024: “Why are oil and chemical spills concentrated in river and coastal regions?Link