Summertime high resolution variability of atmospheric formaldehyde and non-methane volatile organic compounds in a rural background area

• Published in: The Science of the total environment Vol. 647; pp. 862 - 877
• Main Authors: de Blas, Maite, Ibáñez, Pablo, García, Jose Antonio, Gómez, Maria Carmen, Navazo, Marino, Alonso, Lucio, Durana, Nieves, Iza, Jon, Gangoiti, Gotzon, de Cámara, Estíbaliz Sáez
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 10.01.2019
• Subjects: Biogenic Volatile Organic Compounds (BVOCs); Formaldehyde; Hantzsch fluorimetry; Non methane hydrocarbons (NMHC); Rural background; Tropospheric ozone; Tropospheric ozone; Hantzsch fluorimetry; Non methane hydrocarbons (NMHC); Rural background; Formaldehyde; Biogenic Volatile Organic Compounds (BVOCs)
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2018.07.411

On rural background areas atmospheric formaldehyde (HCHO) is important for its abundance and chemical reactivity, directly linked to the tropospheric ozone formation processes. HCHO is also toxic and carcinogenic to humans. Atmospheric HCHO was continuously measured in summer 2016 during 81 days (N = 6722, average: 1.42 ppbv) in a rural background area in Northern Spain, Valderejo Natural Park (VNP) using a Hantzsch fluorimetric system. To better characterize the photochemical processes the database was completed with hourly measurements of 63 Non-Methane Hydrocarbons (NMHC) performed by gas chromatography and other common atmospheric pollutants and meteorological parameters. HCHO mixing ratios were highly correlated with ozone and isoprene. Cloudy and rainy days, with low temperature and radiation, led to low HCHO mixing ratios, with maxima (<2 ppbv) registered around 14 UTC. On days with increased radiation and temperature HCHO maxima occurred slightly later (<6 ppbv, ≈16:00 UTC). During clear summer days with high temperature and radiation, two HCHO peaks were registered daily, one synchronized with the radiation maximum (≈3–4 ppbv, ≈13:00 UTC) and an absolute maximum (<10 ppbv, ≈18:00 UTC), associated with the addition of HCHO coming into VNP due to inbound transport of old polluted air masses. In the ozone episode studied, the processes of accumulation and recharge of ozone and of HCHO ran in parallel, leading to similar daily patterns of variation. Finally, HCHO mixing ratios measured in VNP were compared with other measurements at rural, forested, and remote sites all over the world, obtaining similar values. [Display omitted] •Summertime HCHO mixing ratios were continuously measured in a rural forested area.•A high-time resolution database was obtained: 15 min-averaged HCHO and hourly NMHCs.•HCHO mixing ratios correlated with ozone and isoprene.•Meteorological conditions determined HCHO peaks and daily profile.•An extra amount of HCHO was observed in clear hot days.