|M.Sc Student||Hirshel Nurit|
|Subject||Sub-urban Variability in Particulate Matter Levels in|
|Department||Department of Agricultural Engineering||Supervisor||Professor David Broday|
This work studies differences in attributes of airborne particulate pollution in proximate paired neighborhoods in Haifa. Real time sampling of ambient PM concentrations, up to 10 micron (PM10), and of carbonaceous matter (Black Carbon) was performed during an intensive field campaign in the spring and summer of 2004. Ambient particulate matter (PM) can originate from local emissions (i.e., industrial and traffic-related), atmospheric reactions (oxidation, photochemical) that produce secondary pollutants (which condense and coagulate), and from transport and dispersion of particles originated from remote areas (e.g., mineral dust, sea salt).
The objective of this work was to evaluate the urban-scale spatiotemporal variability of PM from real time measurements, and to study possible mechanisms that can explain the origin of such a variability, including local meteorology, emissions (traffic related), and the possible effect of urban trees.
The paired sites are characterized by similar population densities and neighborhood-wise socioeconomic (deprivation) indexes but show distinct canopy coverage. The data clearly indicate sub-urban (neighborhood) scale variations in any of the measured PM attribute, such as concentrations, size distribution, and carbonaceous matter content.
A bi-modal particle size distribution (accumulation and coarse modes) has been observed at all the neighborhoods during both sampling campaigns (spring and summer). There are clear differences between the paired sampling neighborhoods, with Ramat Alon and Vardiya (the less vegetated neighborhoods) displaying higher morning-noon PM concentrations than the more vegetated Ramot Remez and Romema. While PM10 levels at Vardiya are higher than at Romema (statistically significant) both during the morning-noon and the afternoon-evening, a mixed trend is apparent at the pair R. Alon and R. Remez, with higher levels of all size-fractions in R. Alon in the morning and lower levels in the evening. The lowest summer concentrations of BC and OC containing PM were observed at G. Hagana (background site at Mt. Carmel National Park) and attributed to the lack of heavy traffic volume there.
Real-time data from this study suggest that the variation of different PM attributes cannot be associated with comparable variations of micro-meteorology parameters. It appears as if, due to their geographical proximity, the paired neighborhoods are affected by the same air masses. Hence, the local meteorology as well as the neighborhood traffic profile (including public transportation) cannot be the sole reason for the observed concentration differences between the paired proximate neighborhoods. Rather, it seems that the sub-urban scale differences may be caused by local removal processes, in particular interception by vegetation.