Spatial and Temporal Variability of Ground-Level Ozone, Carbon Dioxide, and Water Vapor Across Different Landscapes in Peru

During June and July 2024, we collected data to assess the spatial and temporal variability of greenhouse gasses across different landscapes and throughout the cities of Lima and Cusco. The studied landscapes included a cloud forest, rainforest in the western Amazon, and urban areas in Lima and Cusco. Ambient abundances of greenhouse gasses such as carbon dioxide, ground-level ozone, and water vapor were measured along horizontal transects in the study sites. During each collection, we collected data including air temperature, relative humidity, and photosynthetically active radiation levels. All data from the instruments were collected using a data logger, which recorded and stored the resulting information. We developed the ILLAPA-G backpack unit (Illapa meaning Incan god of thunder and lightning, G representing grounded), which included an ozone monitor, and a carbon dioxide and water vapor analyzer to study the spatial distribution of greenhouse gasses at the ground level. We analyzed the data sets using Python code that calculated the average gas mixing ratios for each research site. Relative frequency distributions were then computed to display the spatial variability of individual greenhouse gasses. We found that ozone mixing ratios were highest along the coast in Lima, with an average of 26 parts per billion (ppb), on a day when there was a large amount of incoming solar radiation present, and were lowest in the Manu Rainforest, with an average of 1 ppb, where the most ozone surface dry deposition occurred. Carbon dioxide levels were highest in the Manu Rainforest, with a mean of 470 parts per million (ppm), where historically there has been a carbon sink due to photosynthesis, and lowest in Lima along the coast of the Pacific Ocean, with a mean of 406 ppm. Water vapor was highest on the Manu Trail, with a mean of 7.78 mmol/mol, where the largest amount of precipitation and evapotranspiration occurred, and lowest in Cusco, with a mean of 0.11 mmol/mol, where the relative humidity was the lowest. This study provides a unique dataset from traditional air quality monitoring methods that reveals significant differences in greenhouse gas concentrations for each landscape, suggesting that there are variations in greenhouse gas sources and sinks throughout Peru that could be causing this range in concentrations.