Elemental abundance patterns in the Galactic disk constrain theories of the formation and evolution of the Milky Way .
H ii region abundances are the result of billions of years of chemical evolution .
We made radio recombination line and continuum measurements of 21 H ii regions located between Galactic azimuth Az = 90 { } ^ { \circ } -130 { } ^ { \circ } , a previously unexplored region .
We derive the plasma electron temperatures using the line-to-continuum ratios and use them as proxies for the nebular [ O/H ] abundances , because in thermal equilibrium the abundance of the coolants ( O , N , and other heavy elements ) in the ionized gas sets the electron temperature , with high abundances producing low temperatures .
Combining these data with our previous work produces a sample of 90 H ii regions with high quality electron temperature determinations .
We derive kinematic distances in a self-consistent way for the entire sample .
The radial gradient in [ O/H ] is -0.082 \pm 0.014 dex kpc ^ { -1 } for Az = 90 { } ^ { \circ } -130 { } ^ { \circ } , about a factor of two higher than the average value between Az = 0 { } ^ { \circ } -60 { } ^ { \circ } .
Monte Carlo simulations show that the azimuthal structure we reported for Az = 0 { } ^ { \circ } -60 { } ^ { \circ } is not significant because kinematic distance uncertainties can be as high as 50 % in this region .
Nonetheless , the flatter radial gradients between Az = 0 { } ^ { \circ } -60 { } ^ { \circ } compared with Az = 90 { } ^ { \circ } -130 { } ^ { \circ } , are significant within the uncertainty .
We suggest that this may be due to radial mixing from the Galactic Bar whose major axis is aligned toward Az \sim 30 { } ^ { \circ } .