# The factors should be considered to determine one specific pollutant originated from regional transportation?

Ideally, one pollutant (e.g. organic carbon, heavy metals, sulfate) should be the mixed result of local emissions and regional transportation.

To quantify the contribution of local emissions is of great significance especially for the species with serious health issues.

Without the support of complex 3-D model results which may also introduce uncertainty due to the input emission files, I want to discuss some factors to assess the regional impact based on the ground observations.

For example, one aerosol component $X$ was measured in several sites within the study region. Here are some criteria I propose to determine whether local emission or regional sources matters.

(1) The spatial variability of the concentration levels. If the mass loading of the species in different sites is small, there might be the obvious impact of regional transportation from the outer regions.

(2) The seasonal pattern with meteorology analysis. The wind direction pattern or the air mass trajectories pattern should be varied in different seasons. A priori knowledge on the emission hotspot for a larger area is also essential. If the elevated concentrations most occur when the study region is in the downstream of the high emission region, the higher level should be ascribed to the regional transportation.

Any comments, opinions or related technology would be greatly appreciated.

• Does local source refer to sources inside the study area and regional the ones outside it? – Communisty Nov 22 '17 at 12:57
• As item (3) I would add the ratio between different pollutants: e.g. break and tire abrasion can be identified by specific rations between some heavy metals in your PM. Thus, one can make source apportionment studies based in this information. Item (4): Based on (3), one can look on the degradation of primary species or the formation of secondary species and combine them with the information of (3). Thus, it is possible to calculate the age of the air pollution from a specific source. – daniel.neumann Nov 22 '17 at 13:30
• Although, (3) and (4) cannot be applied to all types of emission sources, one can possibly make assumptions on the $NO_X$ emissions of cars on the base of tire or break abrasion emissions and, hence, allocate a part of the measured $NO_X$ to road transport emissions. – daniel.neumann Nov 22 '17 at 13:32
• @Communisty, that's correct in my question. – Han Zhengzu Nov 23 '17 at 0:45
• @daniel.neumann. Thanks for your valuable comments. You pointed out the source indicator species as well as the secondary formation issues which are both valuable – Han Zhengzu Nov 23 '17 at 12:31