Yan Mingquan, Mo Shansheng, Liu Zhongli, Korshin Gregory
College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871, China.
Environ Sci Technol. 2025 Apr 15;59(14):7156-7164. doi: 10.1021/acs.est.5c01019. Epub 2025 Apr 1.
The application of the Bouguer-Lambert-Beer (BLB) Law is limited to dissolved organic matter (DOM) in the environment due to the wide distribution of overlapping chromophores with different molar absorptivities (ε). Here, we report our findings demonstrating the existence of an inverse relationship between and the spectral slope () in the absorption spectra of chromophoric DOM (CDOM). Specifically, ε values at 275 and 380 nm are directly proportional to the square of the root-mean-square width of the Gaussian peak () located at 4.80 eV (258 nm) and 3.79 eV (327 nm), and is inversely proportional to the values of of the right half of log-transformed spectra of the Gaussian peak with respect to wavelength, corresponding to at 275-295 and 380-443 nm in spectra, respectively. This finding expands the applicability of the BLB Law to uniformly quantify DOC concentrations in inland, coastal, and pelagic waters (30-3000 μmol·L, = 7745, = 0.97). Furthermore, the relationship between and aids in interpreting the absorbance spectra of DOM, providing valuable insights into its composition and properties. This finding represents a significant advancement in expanding the applications of UV-vis spectroscopy in CDOM monitoring from micro to global scales.
由于具有不同摩尔吸光系数（ε）的重叠发色团广泛分布，布格-朗伯-比尔（BLB）定律的应用仅限于环境中的溶解有机物（DOM）。在此，我们报告了我们的研究结果，证明在发色溶解有机物（CDOM）的吸收光谱中，ε与光谱斜率（S）之间存在反比关系。具体而言，275和380 nm处的ε值与位于4.80 eV（258 nm）和3.79 eV（327 nm）的高斯峰的均方根宽度（σ）的平方成正比，并且S与高斯峰相对于波长的对数变换光谱右半部分的σ值成反比，分别对应于光谱中275 - 295和380 - 443 nm处的S。这一发现扩展了BLB定律在统一量化内陆、沿海和远洋水域（30 - 3000 μmol·L，R² = 7745，p = 0.97）中溶解有机碳（DOC）浓度方面的适用性。此外，ε与S之间的关系有助于解释DOM的吸收光谱，为其组成和性质提供有价值的见解。这一发现代表了在将紫外可见光谱在CDOM监测中的应用从微观尺度扩展到全球尺度方面的重大进展。
