Satellite observations of Mexico City pollution outflow from the Tropospheric Emissions Spectrometer (TES)

Concurrent tropospheric O₃ and CO vertical profiles from the Tropospheric Emission Spectrometer (TES) during the MILAGRO/INTEX-B aircraft campaigns over the Mexico City Metropolitan Area (MCMA) and its surrounding regions were used to examine Mexico City pollution outflow on a regional scale. The pollution outflow from the MCMA occurred predominantly at 600–800 hPa as evident in O₃, CO, and NO_x enhancements in the in situ aircraft observations. TES O₃ and CO are sensitive to the MCMA pollution outflow due to their relatively high sensitivities at 600–800 hPa. We examined O₃, CO, and their correlation at 600–800 hPa from TES retrievals, aircraft measurements, and GEOS-Chem model results. TES captures much of the spatial and day-to-day variability of O₃ seen in the in situ data. TES CO, however, shows much less spatial and day-to-day variability compared with the in situ observations. The ΔO₃/ΔCO slope is significantly higher in the TES data (0.43) than the in situ data (0.28) due partly to the lack of variability in TES CO. Extraordinarily high ΔO₃/ΔCO slope (0.81) from TES observations at 618 hPa over the Eastern U.S. was previously reported by Zhang et al. [Zhang, L., Jacob, D.J., Bowman, K.W., et al., 2006. Ozone–CO correlations determined by the TES satellite instrument in continental outflow regions. Geophys. Res. Lett. 33, L18804. 10.1029/2006GL026399.]. Thus the application of TES CO–O₃ correlation to map continental pollution outflow needs further examination.     

Characterizing the long-range transport of black carbon aerosols during Transport and Chemical Evolution over the Pacific (TRACE-P) experiment

A major aircraft experiment Transport and Chemical Evolution over the Pacific (TRACE-P) mission over the NW Pacific in March-April 2001 was conducted to better understand how outflow from the Asian continent affects the composition of the global atmosphere. In this paper, a global climate model, GEOS-Chem is used to investigate possible black carbon aerosol contributions from TRACE-P region. Our result depicts that absorbing black carbon ("soot") significantly outflow during lifting to the free troposphere through warm conveyor belt and convection associated with this lifting. The GEOS-Chem simulation results show significant transport of black carbon aerosols from Asian regions to the Western Pacific region during the spring season. As estimated by GEOS-Chem simulations, approximately 25% of the black carbon concentrations over the western pacific originate from SE Asia in the spring.     

Monitoring of the physical parameters and evaluation of the chemical composition of river and groundwater in Calabar (Southeastern Nigeria)

A 12-month study was carried to assess the seasonal and tidal effects on the physical parameters of river and groundwater, which constitute the major potable water sources in Calabar (Nigeria). The study also included an evaluation of the chemical composition of the different water bodies and their relationship. The results show that there was a significant seasonal effect on dissolved oxygen (DO) and nitrate in groundwater on one hand, and on temperature, redox potential (Eh), and DO in river water on the other. Also, a significant tidal influence exists on DO in both river-and groundwater. Comparison between groundwater and river water show statistically significant difference in EC, TDS, Eh, DO, Na, Cl and NO(3). The significant differences in EC, TDS, Na and Cl are due to tidal flushing. The difference in Eh is due to geology of the area while, NO(3) is as a result of anthropogenic pollution. The concentrations of ions in the river and groundwater for the different seasons and tidal cycles show an inverse relationship, while the river water is generally more concentrated than the groundwater. Using a binary mixing model, estimates show that the degree of mixing of river water and groundwater is low, with values of between 1.93% and 2.76% respectively, in the western and eastern parts of the study area. The study concludes that tidal flushing, anthropogenic effects and oxygen supply during recharge contribute to the shaping of water chemistry in the area.