Koo Bonyoung, Wilson Gary M, Morris Ralph E, Dunker Alan M, Yarwood Greg
ENVIRON International Corporation, 773 San Marin Drive, Novato, California 94998, USA.
Environ Sci Technol. 2009 Sep 1;43(17):6669-75. doi: 10.1021/es9008129.
Two efficient methods to study relationships between particulate matter (PM) concentrations and emission sources are compared in the three-dimensional comprehensive air quality model with extensions (CAMx). Particulate source apportionment technology (PSAT) is a tagged species method that apportions concentrations of PM components to their respective primary precursors, e.g., sulfate is apportioned to SOx, nitrate to NOx, etc. The decoupled direct method (DDM) calculates first-order sensitivities of PM concentrations to model inputs. Both tools were applied to two month long (February and July) PM modeling episodes and evaluated against changes in PM concentrations due to various emission reductions. The results show that source contributions calculated by PSAT start to deviate from the actual model responses as indirect effects from limiting reactants or nonprimary precursor emissions become important The DDM first-order sensitivity is useful for determining source contributions only if the model response to input changes is reasonably linear. For secondary inorganic PM, the response is linear for emission reductions of 20% in all cases considered and reasonably linear for reductions of 100% inthe case of on-road mobile sources. The model response for secondary organic aerosols and primary PM remains nearly linear to 100% reductions in anthropogenic emissions.
在具有扩展功能的三维综合空气质量模型（CAMx）中，对两种研究颗粒物（PM）浓度与排放源之间关系的有效方法进行了比较。颗粒物源解析技术（PSAT）是一种标记物种方法，可将PM成分的浓度分配到其各自的主要前体，例如，硫酸盐分配到SOx，硝酸盐分配到NOx等。解耦直接法（DDM）计算PM浓度对模型输入的一阶灵敏度。这两种工具都应用于为期两个月（2月和7月）的PM建模时段，并根据各种减排措施导致的PM浓度变化进行评估。结果表明，随着限制反应物或非主要前体排放的间接影响变得重要，PSAT计算的源贡献开始偏离实际模型响应。仅当模型对输入变化的响应合理呈线性时，DDM一阶灵敏度才有助于确定源贡献。对于二次无机PM，在所考虑的所有情况下，减排20%时响应呈线性，对于道路移动源减排100%的情况，响应合理呈线性。对于二次有机气溶胶和一次PM，人为排放减少100%时，模型响应几乎保持线性。
