  We present a measurement of the angular power spectrum of the cosmic
far-infrared background (CFIRB) anisotropies in one of the extragalactic fields
of the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) at 250, 350
and 500 \mu m bands. Consistent with recent measurements of the CFIRB power
spectrum in Herschel-SPIRE maps, we confirm the existence of a clear one-halo
term of galaxy clustering on arcminute angular scales with large-scale two-halo
term of clustering at 30 arcminutes to angular scales of a few degrees. The
power spectrum at the largest angular scales, especially at 250 \mu m, is
contaminated by the Galactic cirrus. The angular power spectrum is modeled
using a conditional luminosity function approach to describe the spatial
distribution of unresolved galaxies that make up the bulk of the CFIRB.
Integrating over the dusty galaxy population responsible for the background
anisotropies, we find that the cosmic abundance of dust, relative to the
critical density, to be between \Omega_dust=10^{-6} and 8 x 10^{-6} in the
redshift range z ~ 0-3. This dust abundance is consistent with estimates of the
dust content in the Universe using quasar reddening and magnification
measurements in the SDSS.
