Common Contaminants in Urban Watersheds - Urban Watersheds: Geology, Contamination, and Sustainable Development - page 256

Scripps Institution of Oceanography

NOAA Earth System Research Laboratory

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1960 1970 1980 1990 2000 2010

Year

FIGURE 7.23
Carbon dioxide concentrations from 1960 to 2008 measured at Mauna Loa, Hawaii. (From National Oceanic and
Atmospheric Administration (NOAA), Atmospheric CO 2 at Mauna Loa observatory, http://www.esrl.noaa.gov/
gmd/ccgg/trends (accessed June 28, 2010), 2010.)

Greenhouse gases originate from a variety of sources, such as (USEPA 2009g)

• Fossil fuel combustion
• Coal
• Gasoline and diesel fuel in automobiles and trucks
• Aviation fuels
• Home heating fuels such as home heating oil and kerosene
• Industrial processes-refineries and cement making. Cement making is an often
overlooked source; it accounts for 5%-7% of anthropogenic CO 2 (Worrell and
Galitsky 2004).
• Waste disposal facilities
• Electrical generation
• Mining
• Residential and commercial sources
• Agriculture

Figure 7.24 shows a breakdown of yearly greenhouse gas emissions by country of origin.
Increasing carbon dioxide levels in the atmosphere have been linked to the burning
of fossil fuels (USEPA 2009g), and the evidence is clear. Global fossil fuel emissions have
increased to 8000 million Metric Tons of carbon in 2004 compared to 2500 million Metric
Tons in 1950. Figure 7.25 shows the percent contribution of each type of greenhouse gas on
a global scale (USEPA 2010b).

7.8.9 Carbon Monoxide

Carbon monoxide (CO) is a colorless, odorless, nonirritating gas that is very toxic to
humans and animal life (USDHH 2009). Carbon monoxide is formed naturally and