Gustavo Ratto

Preliminary wind analysis regarding different speed ranges in the city of La Plata, Argentina

La Plata city (approximately 800 000 inhabitants) has intense traffic and industrial activity; nevertheless, the city has no governmental air monitoring network for air pollutants and winds have been scarcely studied. Wind observations provided here (covering 1998- 2007) belong to a weather station that was contrasted against the unique governmental site in the city area (the Airport). The present preliminary study analyses wind direction frequencies according to wind speeds and emphasizes wind patters within the first hour after calm occurrences. Results show that independently of the wind speed, wind direction frequency roses are in general similar to each other. Low wind speeds may occur most of the time (on average 58.2 %) and together with calm occurrences (on average 17.1% ) constitute an important factor for the accumulation of air pollutants. The proposed “outgoing of calm” wind direction frequency roses were found to be appropriate to gain knowledge in the structure of winds that transport pollutants towards exposed population after calm occurrences. Long term systematic meteorological fieldworks should be

Development of a nondispersive UV-visible analyzer for simultaneous measurements of SO2 and NO2 in stacks emissions

12 Non-dispersive analyzers have been used for measurement of gases for many years and were recently introduced as on-line meters for continuous stack emission measurements in industrial plants. SO2 and NO2 are among the most important gases in the emissions of the petrochemical industry. The development of a UV-visible meter for these gases is presented. It consists of three optical channels sensing different spectral regions: 300 nm for SO2, 380 nm for NO2 and 320 nm used as a common reference. Each channel has an interference filter of 10 nm bandwidth centered at each channels wavelength. Each filter is followed by a photodiode and its electronics which are housed in a single compartment with no moving parts. An incandescent lamp with high output in the UV region was selected and mounted on the opposite side of the stack by appropriate flanges. The equipment was designed to measure in the range between 0 and 500 ppmv with a resolution of about 2 ppmv. Performance parameters like signal stability, dark current, detection limit and calibration curves are shown.