11

Ironically, this leads to putting more things into the ocean, as a great deal of waste is left by the

fishing industry.

Oil spills and pollution from the oil industry is a large, tangible constituent of water

pollution. An estimated 0.25% of the world oil production ends up in the sea. This is

approximately six million tons per year.^{2 3}

There are several ways oil can end up in waterways;

through road runoff (363 million gallons a year), by routine maintenance of ships (137 million

gallons a year), via air pollution (92 million gallons a year), by natural seepage (62 million

gallons a year), through offshore drilling (15 million gallons a year), and via big spills from

tanker incidents (37 million gallons a year).^{2 4}Road runoff, which is more than just runoff from

vehicles, includes oil from engine oil changes. Routine maintenance involves oil from bilge

cleaning and other ship operations. These processes release millions of gallons of oil into

waterways through repetitive discharges. Although each release may only contain a few gallons,

repeated discharges equal putting 137 million gallons of oil a year into the oceans. Air pollution

ends up in rain, which settles again over land and water. There is natural seepage from the ocean

bottom and eroding sedimentary rocks. Offshore drilling pollutes the surrounding ocean with oil

via courtesy spills and routine, operational discharges.^{2 5}

23 _{http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/OCDST/shuttle_oceanography_web/oss_122.html.} 24 _{http://www.ic.ucsc.edu/~pmmckerc/elements/water/pollution-ocean-oil.html.} 25 _{http://www.ic.ucsc.edu/~pmmckerc/elements/water/pollution-ocean-oil.html/.}