Table 2. Concentrations of Cr and Ni in 2010 Tar Balls and Oil.

sample type	location	Cr (ppma)	Ni (ppm)
tar ball 1	Pensacola, FL	0.49	2.36
tar ball 2	Pensacola, FL	0.36	1.24
tar ball 3	Pensacola, FL	NDb	2.02
tar ball 4	Mobile, AL	0.40	0.24
tar ball 5	Grand Isle, LA	2.32	4.94
tar ball 6	Grand Isle, LA	4.75	8.46
oil slick 1	29°17′56″ N, 89°57′35″ W	ND	2.29
oil slick 2	29°17′56″ N, 89°57′35″ W	ND	3.70
crude oil	Deepwater Horizon riser	<0.05	2.18

^appm = parts per million (measured as mg/kg).

^bND = not detectable.