# Variations in Atmospheric $$CO_2$$ Mixing Ratios across a Boston, MA Urban to Rural Gradient

 Title: Variations in Atmospheric $$CO_2$$ Mixing Ratios across a Boston, MA Urban to Rural Gradient Author: Briber, Brittain M.; Hutyra, Lucy R.; Dunn, Allison L.; Raciti, Steve M.; Munger, J. William Note: Order does not necessarily reflect citation order of authors. Citation: Briber, Brittain M., Lucy R. Hutyra, Allison L. Dunn, Steve M. Raciti, and J. William Munger. 2013. Variations in atmospheric $$CO_2$$ mixing ratios across a Boston, MA urban to rural gradient. Land 2(3): 304-327. Full Text & Related Files: Briber_land-02-00304.pdf (1.565Mb; PDF) Abstract: Urban areas are directly or indirectly responsible for the majority of anthropogenic $$CO_2$$ emissions. In this study, we characterize observed atmospheric $$CO_2$$ mixing ratios and estimated $$CO_2$$ fluxes at three sites across an urban-to-rural gradient in Boston, MA, USA. $$CO_2$$ is a well-mixed greenhouse gas, but we found significant differences across this gradient in how, where, and when it was exchanged. Total anthropogenic emissions were estimated from an emissions inventory and ranged from $$1.5 to 37.3 mg·C·ha^{-1}·yr^{-1}$$ between rural Harvard Forest and urban Boston. Despite this large increase in anthropogenic emissions, the mean annual difference in atmospheric $$CO_2$$ between sites was approximately 5% $$(20.6 \pm 0.4 ppm)$$. The influence of vegetation was also visible across the gradient. Green-up occurred near day of year 126, 136, and 141 in Boston, Worcester and Harvard Forest, respectively, highlighting differences in growing season length. In Boston, gross primary production—estimated by scaling productivity by canopy cover—was ~75% lower than at Harvard Forest, yet still constituted a significant local flux of $$3.8 mg·C·ha^{-1}·yr^{-1}$$. In order to reduce greenhouse gas emissions, we must improve our understanding of the space-time variations and underlying drivers of urban carbon fluxes. Published Version: doi:10.3390/land2030304 Terms of Use: This article is made available under the terms and conditions applicable to Other Posted Material, as set forth at http://nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of-use#LAA Citable link to this page: http://nrs.harvard.edu/urn-3:HUL.InstRepos:10886744 Downloads of this work: