Table 2

Table 2. Summary of semivariance analyses for all kriged continuous surfaces. PAH stands for polycyclic aromatic hydrocarbons. K_e stands for UV extinction coefficients.


Layer	Model	Lag distance	Lag interval	Range	Semivariance R²	Number of neighbors	Search radius

October 1998 K_e	Linear	8000	1075	1209	0.5	16	4000

May 1999 K_e	Linear	8000	708	4251	0.79	16	4000

August 1999 K_e	Linear	8000	1100	1094	0.46	16	4000

Silt-clay	Exponential	8000	800	1677	0.91	16	4000

Total PAH			800	9687	0.83	16	4000