Source-receptor relationship

If the receptor region is, for example, the Adirondack Mountains region of New York State, a possible specific question of the overall source-receptor problem would be which states contribute to acid deposition in the area. One could make the question even more specific, by asking what fraction of the sulfate deposition in the Adirondacks is emitted as SO2 in the state of Ohio. The development of source-receptor relationships is a key policy question associated with acid deposition. 

Development of reliable source-receptor relationships remains a challenging task. The magnitude of the task may be appreciated by envisioning North America, an area of about 2500 x 2500 km gridded in cells of 250 x 250 km. This results in some 100 cells, each of 

Derivation of source-receptor relationships include statistical, Lagrangian, and Eulerian approaches (see Chapters 25 and 26). Despite significant progress during the last two decades, limitations of these models leave uncertainties of a factor of 2 in the most substantial property of source to receptor relationships—the mean transport distance (Schwartz 1989). 

The source-receptor relationships we just discussed, if available, tell us the fraction of acid deposition at a receptor that results from emissions of a particular source over a given averaging time. While this information is valuable, we would like to know something more in order to design emission control strategies. What we need to calculate is how much deposition of, say, sulfate at a receptor site will be reduced if S02 emissions by a certain source are reduced by a certain amount. Let us use as an example the estimate presented in the previous section. Assume that the utility S02 emissions in the Lower Ohio Valley are reduced by 50% (cut in half). This area as of about two decades ago (according to the RADM results) appeared to contribute on average 1.8kg(S)ha 1 yr 1 to the sulfur deposition on the Adirondacks. What would be the contribution after the emission reductions  

Let us take a step back and synthesize what we know about the behavior of the system and its response to an S02 emission change. A reasonable assumption for our discussion is that this local change of emissions will not affect the meteorological component of the acid deposition process (windspeed and direction, mixing, cloud occurrence and pollutant processing, rainfall, etc.). This leaves us free to concentrate on the changes of the chemical component of acid deposition. Simplifying the problem this way, we can now focus on the two components of the acid deposition—the clean-air and the cloud-related pathways. The clean-air processes include emissions of S02, atmospheric transport, conversion to sulfate by reaction with the OH radical, and dry deposition of S02 and sulfate. If we follow 

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European countries, source-receptor relationships were evaluated for the composite region the European Union—EU15). The contribution of external anthropogenic sources to EU amounted to 12%. 

In its simplest form of interest for policy and regulatory purposes, linearity is often treated in terms of source-receptor relationships. That is, if the emissions of the precursor S02 are lowered by 50%, will the deposition of sulfate also decrease by 50% at all receptor sites ... 

G. M. Hidy, Atmospheric Sulfur and Nitrogen Oxides Eastern North American Source Receptor Relationships, Academic Press, Odando, Fla., 1994. 

Stohl A (1996) Trajectory statistics - a new method to establish source-receptor relationships of air pollutants and its application to the transport of particulate sulfate in Europe. Atmos Environ 30 579-587... 

Characterization of variability in deposition is important for bounding uncertainties in exposure levels. Also this aspect of deposition is crucial to describing the "predictability of source-receptor relationships (SRRs)(4). 

The reliable estimation of source impact on receptor conditions is difficult from theory because of undetermined uncertainties. Inference from comparison between emissions and measurements offers an alternative to calculations. Measurements in the East have yielded ambiguous source-receptor relationships. However, evidence suggests that recent changes in sulfate deposition in the West are linked with relatively large changes in SO emissions from non-... 

In this study we have employed the simultaneous collection of atmospheric particles and gases followed by multielement analysis as an approach for the determination of source-receptor relationships. A number of particulate tracer elements have previously been linked to sources (e.g., V to identify oil-fired power plant emissions, Na for marine aerosols, and Pb for motor vehicle contribution). Receptor methods commonly used to assess the interregional impact of such emissions include chemical mass balances (CMBs) and factor analysis (FA), the latter often including wind trajectories. With CMBs, source-strengths are determined (1) from the relative concentrations of marker elements measured at emission sources. When enough sample analyses are available, correlation calculations from FA and knowledge of source-emission compositions may identify groups of species from a common source type and identify potential marker elements. The source composition patterns are not necessary as the elemental concentrations in each sample are normalized to the mean value of the element. Recently a hybrid receptor model was proposed by Lewis and Stevens (2) in which the dispersion, deposition, and conversion characteristics of sulfur species in power-plant emissions... 

Fig. 7.4 (a) Average surface ozone concentration (in ppb) over 8 days at 16 00. Mexican summer time for the baseline 2010 emission scenario, (b) Source-receptor relationship for the 50 grid cells with highest N02-concentrations within the conurbation of Munich during a 4 day period... 

Third, additional dispersion modeling was performed to identify source-receptor relationships and define culpable sources (those sources that have the largest contributions to the total impact) for the receptor points identified. These results are illustrated in Fig. 14. For example, at the point of highest concentration... 

Once formed, sulfates readily combine with atmospheric ammonia to form ammonium sulfate ((NH4)2S04) or ammonium bisulfate (NH4HSO4). Formation of these species can be a significant sink of atmospheric ammonia. As mentioned above, the interaction between sulfates, nitrates, and ammonia is a cause of nonlinearity in aerosol source-receptor relationships. 

The trajectory model was used to determine the deposition pattern away from a source of sulphur dioxide with unit emission. This pattern defines the source-receptor relationship for sulphur, see equation 1 ... 

Husar, R.B., Patterson, D.E. and Wilson, W.E. (1985b) Monte Carlo simulation of regional air pollution semiempirical regional scale source-receptor relationship. In internal EPA review. 

Hidy, G. M. (1984) Source-receptor relationships for acid deposition Pure and simple J. Air Pollut. Control Assoc. 34, 518-531. 

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