Fig 3. Discrimination of PAHs in reference and oiled samples by principal component analysis.
S. Ayu source oil is illustrated with solid circles. Source oil types were marine diesel oil (MDO), intermediate fuel oil light (IFOL), and intermediate fuel oil heavy (IFOH). Solid squares indicate oil from sediment in 2004–2005 and open diamonds indicate oil from 2008 sediment. Black triangles indicate non-oiled reference samples and open triangles represent 2008 data; weathering was not estimated (NE) in these. Anchor tar from an unknown origin is also included for comparison. One sample with hydrocarbons from the oiled area was not verified as S. Ayu oil (annotated). Percent total chrysenes in oiled samples is indicated by color; small values indicate the least weathered samples, large values indicate the most weathering. The first component (PCA 1) explained 28% of the variance and the second (PCA 2) explained 21% of the variance.