Residential use of natural gas (NG) for heating and cooking purposes may contribute significantly to CH4 emissions to the atmosphere. To analyze whether the NG demand in the city of Tandil, Argentina, contributes to the increase in atmospheric CH4 concentration, we conducted systematic collections of time‐integrated air samples for a year in six city sites with different population and built‐up density. Some meteorological parameters and NG consumption were registered. Atmospheric CH4 concentration ranged from 1.12 to 1.95 mg m−3 (1.72 to 2.84 ppm) with significant seasonal and spatial variations. In all the sites, with the exception of a peri‐urban site bordering rural areas, the maximum CH4 concentrations were measured during the coldest months, with a statistically significant correlation between residential and commercial NG consumption with respect to air temperature (p < 0.001, R = −0.84 to −0.69) and atmospheric CH4 concentration (p < 0.05, R = 0.58 to 0.94). In Argentina, the most popular home heating system is the balanced‐draft heater, which has a thermal efficiency of 39 to 63%. This low efficiency allows us to attribute the highest atmospheric CH4 concentration found during the coldest months mainly to the leaks of the heating systems and the greater residential use of NG. Repairing the gas leaks by increasing thermal efficiency or replacing heating systems with more efficient ones will bring economic, environmental, and health benefits. This study is important for our country where the dependence on the use of NG from heating systems is significant. Core Ideas We studied atmospheric CH4 concentration in an urban area at a southern mid‐latitude. We observed spatial and seasonal variations in atmospheric CH4 concentration. The highest atmospheric CH4 concentrations were measured during the coldest months. Methane concentration and residential natural gas consumption were well correlated. Low‐efficiency heating systems cause an increase in CH4 concentrations.

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We assessed the rates of methane uptake (CH 4 ) by soils of different tree plantations and a control to provide information regarding potential greenhouse gas sequestration by tree plantations of pines, mixed deciduous species and eucalyptus in a natural grassland around 37S, 59W (Argentinean Pampa). A naturalized pasture was used as control. All sites had been agricultural and livestock lands. Each site was sampled three times from December 2012 to May 2013, using five static chambers randomly distributed across an area of *100 m 2 in each site. In the control, methane fluxes were very weak; both negative (uptake) and positive (emission) values were found. Below tree plantations, fluxes were always negative, with statistically significant intersite differences. The highest uptake rates were observed in the mixed deciduous plantation (*10 ng m -2 s -1 ), followed by pines and eucalyptus plantations. Intrasite differences associated with spatial variation were also found. A significant inverse correlation between CH 4 uptake and soil water content was found in the pine and deciduous species plantations (R 2 [ 0.94, p \ 0.1).