星际消光和元素丰度对星际尘埃的组份和尺寸提出了关键的限制。然而，迄今为止绝大部分尘埃模型针对的是银河系中由不同性质的气体和尘埃组成的许多星云的平均消光曲线,这将不可避免地导致星际尘埃特性与星际物理、化学环境之间关系等信息的丢失。我们拟研究100多个样本天体, 在满足星际元素丰度约束的前提下，通过拟合每个样本从近红外到远紫外的消光曲线，得出每个样本天体的尘埃组份和尺寸分布，探索尘埃属性(如尘埃尺寸和组份)、星际元素丰度减损(depletion)与星际物理、化学条件 (如消光AV、消光与选择消光比率RV、氢的数密度<nH>、氢分子占氢总量的比f(H2))之间的关系。另外,通过比较由最佳拟合模型获得的尘埃丰度，结合气相丰度,我们亦将增进对星际元素丰度的了解。

The interstellar extinction and elemental abundances provide crucial constraints on the composition and size of interstellar dust. Practically, most of the extinction modeling efforts have been so far directed to the Galactic average extinction curve which is obtained by averaging over many clouds of different gas and dust properties. Therefore, by modeling the Galactic average extinction, unavoidably, any details concerning the relationship between the dust properties and the physical and chemical conditions of the interstellar environments would have been lost! We will derive the dust composition and size distribution of each sight line for a sample of over 100 individual sight lines by simultaneously both reproducing the observed extinction curve from the near-IR to the far-UV and conforming to the observed abundance constraints. We will also explore the relationships between the derived dust properties (e.g., size, composition), depletions, and the physical and chemical conditions of the interstellar environments (e.g., AV , RV , <nH>、 f(H2)). By comparing the gas-phase abundances with the dust-phase abundances inferred from the best-fit models, we will also gain insight into the reference abundance for which abundance set is the most reliable proxy for the ISM composition.