Tropospheric sources and sinks of gas-phase acids in the Colorado Front Range

Abstract

Abstract. We measured organic and inorganic gas-phase acids in the Front Range of Colorado to better understand their tropospheric sources and sinks using a high-resolution time-of-flight chemical ionization mass spectrometer.

Overview of HOMEChem: House Observations of Microbial and Environmental Chemistry

“…In contrast to indoors, outdoor formic and acetic acid exhibit strong diel patterns during the study, consistent with previous outdoor measurements that indicate photochemical sources of these acids. 77,78,84 The high ([1) indoor/ outdoor concentration ratios for formic and acetic acid are consistent with the interior of the HOMEChem building being a non-photochemical source of these two acids to the atmosphere. Assuming these acids are in steady state with indoor surfaces, we estimate an upper bound emission rate from indoors to outdoors to be 2 Â 10 À4 mol h À1 for formic acid and 1 Â 10 À4 mol h À1 for acetic acid.…”

“…While hydrocarbons like limonene, propane, and isoprene varied following their expected cooking, cleaning and human emissions, the time series of organic acids displayed evidence of more complex sources and sinks. Organic acids are prominent in the outdoor atmosphere, 30,77,78 but also have indoor sources, including human metabolism, building materials, and oxidation chemistry. [79][80][81] Exchange of indoor and outdoor air means that outdoor sources may contribute to indoor air organic acid concentrations.…”

Isocyanic acid (HNCO) and its fate in the atmosphere: a review

“…This instrument also uses so ionisation through proton transfer but from hydronium ions (H 3 O + ) and can detect HNCO mixing ratios from low ppbv up to 1000s of ppbv. [23][24][25][51][52][53] Online CIMS techniques with acetate and iodide reagent ions and PTR-MS instruments have facilitated atmospheric measurements of HNCO providing observations from eld campaigns from 10 locations across three continents (Pasadena, California; 19 Erie, Colorado; 26,54 La Jolla, California; 55 Fort Collins, Colorado; 26 Toronto, Ontario; 30,56 Calgary, Alberta; 50 the marine boundary layer in the Canadian Arctic Archipelago; 57 Mohali, India; 51 Kathmandu Valley, Nepal; 52 and Manchester, UK 58 ) ( Table 1). The number of ambient measurements continues to grow, yet long term datasets are still missing (Fig.…”

“…[40][41][42][43][44][45] Measurements made in La Jolla, Mohali, and Bode all have similar diurnal proles with early morning minimum (4-6 am) and late morning (10-12 am) maximum mixing ratios. 51,52,55 The summertime data set from the Boulder Atmospheric Observatory tower in Erie, CO 54 shows a diurnal cycle similar to that of Pasadena, with an early morning minimum and early aernoon maximum. 54 The Toronto data similarly has minimum mixing ratios in the early morning but shows two distinct maxima throughout the day; one in midmorning (8 am, local max) and one in the early evening (7 pm, absolute max).…”

“…51,52,55 The summertime data set from the Boulder Atmospheric Observatory tower in Erie, CO 54 shows a diurnal cycle similar to that of Pasadena, with an early morning minimum and early aernoon maximum. 54 The Toronto data similarly has minimum mixing ratios in the early morning but shows two distinct maxima throughout the day; one in midmorning (8 am, local max) and one in the early evening (7 pm, absolute max). 30 These measurements were made along the roadside and suggest vehicle emission as a primary source of HNCO.…”