ASSESSMENT OF FIREFIGHTING EFFICIENCY OF VEGETATION FIRES IN CURITIBA-PARANÁ

Vegetation fires, when not controlled, cause economic disruption, temporary loss of vegetation, and damage to soil, fauna and health. To improve the process of fire prevention and firefighting, it is necessary to evaluate the performance of the involved agents. The objective of this study was to evaluate the firefighting efficiency of vegetation fires in the municipality of Curitiba, Paraná, from 2011 to 2015, using records from the Fire Department of the Military Police of Paraná. Once the consistency of the fire records was verified, they were classified and information was gathered regarding the extent of burnt area, time of first attack, combat time, main fire-extinguishing methods used, and amount of water used. The results indicate that 88% of the records registered a burnt area inferior or equal to four hectares. In addition, the mean burnt area was of 2,399.21 m², the mean attack time was of 14.1 minutes, and the mean combat time was of 29.9 minutes, all lower than the ones presented by studies from different locations. As for the fire-extinguishing methods, it was verified that smothering equipment and water were used in 66.4 and 60.6% of the records, respectively. The mean amount of water used was of 1,186.56 liters per fire, indicating a minimum volume necessary for water storage containers for firefighting in the study area. Based on the results, we concluded that the firefighting of vegetation fires in Curitiba is efficient.

Climate change effects on soil carbon dynamics: CO2 flux from water-repellent and fire-affected soils

Climate change is increasing the frequency and intensity of droughts and this is expected to enhance the development of soil water repellency: a very common property of both dry and fire-affected soils. In some regions climate change is also increasing the occurrence and severity of wildfires. Large pulses of CO2 flux from soil to the atmosphere caused by heavy rainfall events (i.e. the Birch effect) can contribute substantially to annual C emissions from soils. However, the effect of the first rainfall after a drought on water-repellent soils and the first post-fire rainfall event on soil CO2 flux remain poorly understood. To address these knowledge gaps this research focuses on: i) investigating the effects of soil water repellency on the CO2 pulse after wetting; ii) improving understanding of the effects of vegetation fires on post-fire soil CO2 flux; and iii) studying the role of ash produced naturally during vegetation fires in post-fire soil CO2 flux. The results from this research clearly indicate that water repellency is a key controller of the CO2 pulse following the wetting of dry and fire-affected soils. Both the amount of water and the increase in soil water content after wetting are used as indicators of the magnitude of the Birch effect, but this research suggests that their application in water-repellent soils should be re-evaluated. The findings presented here challenge the conceptual notion that the Birch effect is comprised of one large pulse of CO2 and highlights the need to incorporate high-frequency observations during the period following wetting to capture the entire CO2 response to wetting. The results from this thesis suggest that ash is a key player in post-fire C fluxes and should be considered in post-fire C investigations in order to make realistic predictions of the impacts of vegetation fires on C dynamics.

Spatial and temporal variations of air pollution over 41 cities of India during the COVID-19 lockdown period

In this study, we characterize the impacts of COVID-19 on air pollution using NO2 and Aerosol Optical Depth (AOD) from TROPOMI and MODIS satellite datasets for 41 cities in India. Specifically, our results suggested a 13% NO2 reduction during the lockdown (March 25–May 3rd, 2020) compared to the pre-lockdown (January 1st–March 24th, 2020) period. Also, a 19% reduction in NO2 was observed during the 2020-lockdown as compared to the same period during 2019. The top cities where NO2 reduction occurred were New Delhi (61.74%), Delhi (60.37%), Bangalore (48.25%), Ahmedabad (46.20%), Nagpur (46.13%), Gandhinagar (45.64) and Mumbai (43.08%) with less reduction in coastal cities. The temporal analysis revealed a progressive decrease in NO2 for all seven cities during the 2020 lockdown period. Results also suggested spatial differences, i.e., as the distance from the city center increased, the NO2 levels decreased exponentially. In contrast, to the decreased NO2 observed for most of the cities, we observed an increase in NO2 for cities in Northeast India during the 2020 lockdown period and attribute it to vegetation fires. The NO2 temporal patterns matched the AOD signal; however, the correlations were poor. Overall, our results highlight COVID-19 impacts on NO2, and the results can inform pollution mitigation efforts across different cities of India.

Spatial and Temporal Distribution of Biomass Open Burning Emissions in the Greater Mekong Subregion

Moderate Resolution Imaging Spectroradiometer (MODIS) burnt area products are widely used to assess the damaged area after wildfires and agricultural burning have occurred. This study improved the accuracy of the assessment of the burnt areas by using the MCD45A1 and MCD64A1 burnt area products with the finer spatial resolution product from the Landsat-8 Operational Land Imager/Thermal Infrared Sensor (OLI/TIRS) surface reflectance data. Thus, more accurate wildfires and agricultural burning areas in the Greater Mekong Subregion (GMS) for the year 2015 as well as the estimation of the fire emissions were reported. In addition, the results from this study were compared with the data derived from the fourth version of the Global Fire Emissions Database (GFED) that included small fires (GFED4.1s). Upon analysis of the data of the burnt areas, it was found that the burnt areas obtained from the MCD64A1 and MCD45A1 had lower values than the reference fires for all vegetation fires. These results suggested multiplying the MCD64A1 and MCD45A1 for the GMS by the correction factors of 2.11−21.08 depending on the MODIS burnt area product and vegetation fires. After adjusting the burnt areas by the correction factor, the total biomass burnt area in the GMS during the year 2015 was about 33.3 million hectares (Mha), which caused the burning of 109 ± 22 million tons (Mt) of biomass. This burning emitted 178 ± 42 Mt of CO2, 469 ± 351 kilotons (kt) of CH4, 18 ± 3 kt of N2O, 9.4 ± 4.9 Mt of CO, 345 ± 206 kt of NOX, 46 ± 25 kt of SO2, 147 ± 117 kt of NH3, 820 ± 489 kt of PM2.5, 60 ± 32 kt of BC, and 350 ± 205 kt of OC. Furthermore, the emission results of fine particulate matter (PM2.5) in all countries were slightly lower than GFED4.1s in the range between 0.3 and 0.6 times.