Site characterization on Johnston Island, Johnston Atoll, Pacific Ocea
n, has yielded preliminary data that seabird guano can be an interfere
nce in three common petroleum hydrocarbon quantification methods. Vola
tiles from seabird guano were measured on a hydrocarbon-specific handh
eld vapor meter (catalytic detector) in concentrations as high as 256
ppm by volume total hydrocarbon. Analysis of guano solids produced mea
surable concentrations of total petroleum hydrocarbon (TPH) as diesel
using both an immunoassay test and the EPA 8015 Modified Method. The t
esting was conducted on one surface sample of guano collected from a s
eabird roosting and nesting area. Source species were not identified.
Positive hydrocarbon test results for guano raise concerns regarding t
he effectiveness of standard methods of petroleum-contaminated site ch
aracterization for Johnston Island, other Pacific islands, and coastal
areas with historic or contemporary seabird populations.