diff --git a/chem/module_optical_averaging.F b/chem/module_optical_averaging.F
index ed08817056..893ec09c2c 100644
--- a/chem/module_optical_averaging.F
+++ b/chem/module_optical_averaging.F
@@ -3529,7 +3529,10 @@ end subroutine optical_prep_mam
 ! SAM 7/18/09 - Modal parameters for OC1 (hydrophobic) OC2 (hydrophylic), BC1,BC2,
 ! and sulfate - just use dginia (meters) and sginia from module_data_sorgam.
 ! Not using accumulation mode from d'Almedia 1991 Table 7.1 and 7.2 global model
-!
+! 10/16/18 - A. Ukhov, bug fix: dust particles having radii in the range 0.1-0.46 microns
+! were not accounted in the calculation of the mass redistribution between the GOCART and 
+! MOZAIC grids.
+
 ! This subroutine computes volume-averaged refractive index and wet radius needed
 ! by the mie calculations. Aerosol number is also passed into the mie calculations
 ! in terms of other units.
@@ -3553,7 +3556,7 @@ subroutine optical_prep_gocart(nbin_o, chem, alt,relhum,          &
 ! real*8, DIMENSION (4), PARAMETER :: rb(4)=(/5.d-1,1.5d0,5.d0,1.d1/)
 ! real*8, DIMENSION (4), PARAMETER :: den_seas(4)=(/2.2d3,2.2d3,2.2d3,2.2d3/)
 ! real*8, DIMENSION (4), PARAMETER :: reff_seas(4)=(/0.30D-6,1.00D-6,3.25D-6,7.50D-6/)
-   USE module_data_gocart_dust, only:  ndust, reff_dust, den_dust
+   USE module_data_gocart_dust, only:  ndust, reff_dust, den_dust,ra_dust,rb_dust
 !  real*8, DIMENSION (5), PARAMETER :: den_dust(5)=(/2500.,2650.,2650.,2650.,2650./)
 !  real*8, DIMENSION (5), PARAMETER :: reff_dust(5)=(/0.73D-6,1.4D-6,2.4D-6,4.5D-6,8.0D-6/)
 
@@ -3716,15 +3719,14 @@ subroutine optical_prep_gocart(nbin_o, chem, alt,relhum,          &
 !      WRITE(*,*)'         ','       ',(dlo_sectm(n),n=1,nbin_o)
 !      WRITE(*,*)'         ','       ',(dhi_sectm(n),n=1,nbin_o)
         dustfrc_goc8bin=0.
-        dlogoc=0.46*2.E-6 ! Begin lower dust bin, makes upper limit diam 20 micron diameter 
        do m =1, ndust  ! loop over dust size bins
-       dhigoc = 2.*2.*reff_dust(m)-dlogoc ! hi diameter limit (m)
+        dlogoc = ra_dust(m)*2.E-6  ! low diameter limit (m)
+        dhigoc = rb_dust(m)*2.E-6  ! hi diameter limit (m)
         do n = 1, nbin_o
         dustfrc_goc8bin(m,n)=max(DBLE(0.),min(DBLE(dhi_sectm(n)),dhigoc)- &
                              max(dlogoc,DBLE(dlo_sectm(n))) )/(dhigoc-dlogoc)
        end do
 !      WRITE(*,*)m,dlogoc,dhigoc,(dustfrc_goc8bin(m,n),n=1,nbin_o)
-       dlogoc=dhigoc
        end do
         kcall=kcall+1
 !       ISTOP=1
diff --git a/phys/module_data_gocart_dust.F b/phys/module_data_gocart_dust.F
index 4912304e73..24ebf6ed4e 100644
--- a/phys/module_data_gocart_dust.F
+++ b/phys/module_data_gocart_dust.F
@@ -29,6 +29,11 @@ Module module_data_gocart_dust
 ! real*8, DIMENSION (ndust), PARAMETER :: lo_dust=(/0.1D-6,1.0D-6,1.8D-6,3.0D-6,6.0D-6/)
 ! real*8, DIMENSION (ndust), PARAMETER :: up_dust=(/1.0D-6,1.8D-6,3.0D-6,6.0D-6,10.0D-6/)
 
+  !GOCART bins radii ranges
+  real*8, DIMENSION (5), PARAMETER :: ra_dust(5)=(/1.d-1,1.0d0,1.8d0,3.0d0,6.0d0/)
+  real*8, DIMENSION (5), PARAMETER :: rb_dust(5)=(/1.0d0,1.8d0,3.0d0,6.0d0,10.0d0/)
+
+
 END Module module_data_gocart_dust