Editing Oil spill (section)

==Estimating the volume of a spill==
By observing the thickness of the film of oil and its appearance on the surface of the water, it is possible to estimate the quantity of oil spilled. If the surface area of the spill is also known, the total volume of the oil can be calculated.<ref>''Metcalf & Eddy. Wastewater Engineering, Treatment and Reuse. 4th ed. New York: McGraw-Hill, 2003. 98.''</ref>

{| class="wikitable" style="width:50%;"
|-
!
! colspan="3" | Film thickness
! colspan="2" | Quantity spread
|-
! Appearance
! inches
! mm
! nm
! gal/sq&nbsp;mi
! L/ha
|-
| Barely visible
| style="text-align:center;"| 0.0000015
| style="text-align:center;"| 0.0000380
| style="text-align:center;"| 38
| style="text-align:center;"| 25
| style="text-align:center;"| 0.370
|-
| Silvery sheen
| style="text-align:center;"| 0.0000030
| style="text-align:center;"| 0.0000760
| style="text-align:center;"| 76
| style="text-align:center;"| 50
| style="text-align:center;"| 0.730
|-
| First trace of color
| style="text-align:center;"| 0.0000060
| style="text-align:center;"| 0.0001500
| style="text-align:center;"| 150
| style="text-align:center;"| 100
| style="text-align:center;"| 1.500
|-
| Bright bands of color
| style="text-align:center;"| 0.0000120
| style="text-align:center;"| 0.0003000
| style="text-align:center;"| 300
| style="text-align:center;"| 200
| style="text-align:center;"| 2.900
|-
| Colors begin to dull
| style="text-align:center;"| 0.0000400
| style="text-align:center;"| 0.0010000
| style="text-align:center;"| 1000
| style="text-align:center;"| 666
| style="text-align:center;"| 9.700
|-
| Colors are much darker
| style="text-align:center;"| 0.0000800
| style="text-align:center;"| 0.0020000
| style="text-align:center;"| 2000
| style="text-align:center;"| 1332
| style="text-align:center;"| 19.500
|}

Oil spill model systems are used by industry and government to assist in planning and emergency decision making. Of critical importance for the skill of the oil spill model prediction is the adequate description of the wind and current fields. There is a worldwide oil spill modelling (WOSM) program.<ref>Anderson, E.L., E. Howlett, K. Jayko, V. Kolluru, M. Reed, and M. Spaulding. 1993. The worldwide oil spill model (WOSM): an overview. Pp. 627–646 in Proceedings of the 16th Arctic and Marine Oil Spill Program, Technical Seminar. Ottawa, Ontario: Environment Canada.</ref> Tracking the scope of an oil spill may also involve verifying that hydrocarbons collected during an ongoing spill are derived from the active spill or some other source. This can involve sophisticated analytical chemistry focused on finger printing an oil source based on the complex mixture of substances present. Largely, these will be various hydrocarbons, among the most useful being [[polyaromatic hydrocarbons]]. In addition, both oxygen and nitrogen heterocyclic hydrocarbons, such as parent and alkyl homologues of [[carbazole]], [[quinoline]], and [[pyridine]], are present in many crude oils. As a result, these compounds have great potential to supplement the existing suite of hydrocarbons targets to fine-tune source tracking of petroleum spills. Such analysis can also be used to follow weathering and degradation of crude spills.<ref>{{cite journal | last1 = Wang | first1 = Z. | last2 = Fingas | first2 = M. | last3 = Page | first3 = D.S. | year = 1999 | title = Oil spill identification | journal = Journal of Chromatography A | volume = 843 | issue = 1–2| pages = 369–411 | doi = 10.1016/S0021-9673(99)00120-X}}</ref>