Southeast Environmental Research Center and Department of Chemistry and Biochemistry , Florida International University , Miami , Florida 33179 , United States.
Research Group for Marine Geochemistry , Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg , D-26129 Oldenburg , Germany.
Environ Sci Technol. 2018 Aug 7;52(15):8104-8114. doi: 10.1021/acs.est.8b00190. Epub 2018 Jul 11.
Rivers export roughly 250 Pg of dissolved organic carbon (DOC) to coastal oceans. DOC exported from rivers can be a reflection of watershed dynamics, and changes in land use can lead to shifts in the molecular composition and reactivity of riverine DOC. About 10% of DOC exported from rivers is dissolved black carbon (DBC), a collection of polycondensed aromatic compounds derived from the incomplete combustion of biomass and fossil fuels. While DOC and DBC export are generally coupled, the effects of watershed land use on DBC quality are not well understood. In this study, DBC samples were collected throughout the Altamaha River watershed in Georgia, USA. DBC was characterized using the benzenepoly(carboxylic acid) method and Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). DBC had a more polycondensed character in areas of the watershed with less anthropogenic disturbance. Furthermore, FTICR-MS revealed that DBC became enriched with a lower molecular weight, heteroatomic signature in response to higher anthropogenic activity. As global land cover continues to change, this study demonstrates on a localized scale that watershed land use can influence the export and composition of DBC, which may have further implications for global carbon and nutrient cycling.
河流向沿海海洋输出约 250 太克的溶解有机碳（DOC）。河流输出的 DOC 可以反映流域动态，土地利用的变化会导致河流 DOC 的分子组成和反应性发生变化。约 10%的河流 DOC 是溶解黑碳（DBC），它是由生物质和化石燃料不完全燃烧产生的多环芳烃化合物的混合物。尽管 DOC 和 DBC 的输出通常是耦合的，但流域土地利用对 DBC 质量的影响还不是很清楚。在这项研究中，DBC 样本是在美国佐治亚州的 Altamaha 河流域采集的。使用苯多羧酸法和傅里叶变换离子回旋共振质谱（FTICR-MS）对 DBC 进行了表征。在受人为干扰较小的流域地区，DBC 的多环芳烃特征更明显。此外，FTICR-MS 表明，随着人为活动的增加，DBC 变得更加丰富，具有更低分子量和杂原子特征。随着全球土地覆盖的不断变化，本研究从局部尺度表明，流域土地利用会影响 DBC 的输出和组成，这可能对全球碳和养分循环产生进一步影响。
