RESUMEN
Temporal and spatial distribution of both biogenic and anthropogenic components of atmospheric carbon dioxide (CO2) and methane (CH4) is crucial for understanding the environmental impacts of climate change over urban areas. This research focuses on applying stable isotope source-partitioning studies to determine the interactions between biogenic and anthropogenic CO2 and CH4 emissions in an average-sized city environment. Study signifies the weight of instantaneous variability and diurnal averaging as compared with seasonal records of variations of the atmospheric CO2 and CH4 at a variety of typical urban sites in the city of Wroclaw, conducted during a one-year period from June 2017 to August 2018. The findings reveal distinct temporal variations in atmospheric CO2 and CH4 mole fractions and their isotopic composition. The average atmospheric CO2 and CH4 mole fractions during the study period were 416.4 ± 20.5 ppm, and 1.95 ± 0.09 ppm, respectively. The study highlights the high variability of driving forces, including current energy use patterns, natural carbon reservoirs, planetary boundary layer dynamics, and atmospheric transport. Additionally, the relationship between the evolution of the convective boundary layer depth and the CO2 budget was analyzed using the CLASS model with input parameters based on field observations, resulting in insights such as an increase in the range of 25-65 ppm of CO2 during stable nocturnal boundary layers. The observed changes in stable isotopic signatures of air samples allowed for the identification of two main source categories in the city area: fuel combustion and biogenic processes. The δ13C-CO2 values of collected samples suggest that biogenic emissions dominate (up to 60 % of CO2 excess mole fraction) during the growing season, but are reduced by plant photosynthesis during summer afternoons. In contrast, local fossil-fuel CO2 contribution (up to 90 % of excess CO2 mole fraction) from domestic heating, vehicle emissions, and heat and power plants predominantly influence the urban GHG budget during winter. The δ13C-CH4 values indicate anthropogenic sources related to fossil fuel combustion during winter, with values ranging from -44.2 to -51.4 , while slightly more depleted values, between -47.1 and -54.2 , reflect a larger input of biological processes in the methane urban budget during summer. Overall, instantaneous and hourly variability of the above-mentioned readings of gas mole fraction and isotopic composition, have shown higher variability than seasonal amplitudes. Hence, respecting this granularity is the key to alignment and understanding significance of such localized atmospheric pollution studies. Additionally, the changing overprint of the system's framework, such as variability of wind and atmospheric layering patterns, weather events, provides context of sampling and data analysis at different frequencies.
RESUMEN
On-site odor measurements and mathematical modeling are useful for identifying the odor impact at the source and receptors located in areas adjacent to wastewater treatment plants (WWTPs). Impact of open area sources can be significant and may influence air quality both at the WWTP area and downwind in the surrounding areas. In this work, results of the odor measurements carried out in the spring and summer season for sources within three different mechanical-biological WWTPs in Poland are presented. The odor impact assessment was completed using a Polish reference model. The odor emission scenarios considering the contribution of major odor sources within WWTPs and the seasonal variation were determined. Obtained results showed significant differences between spring and summer seasons. The highest and the lowest measured odor concentrations at the WWTP property line were 75 ouE/m3 (July) and 6.4 ouE/m3 (March), respectively.