Organic Signatures of Surfactants and Organic Molecules in Surface Microlayer and Subsurface Water of Delaware Bay
Organic Signatures of Surfactants and Organic Molecules in Surface Microlayer and Subsurface Water of Delaware Bay
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DOI：
10.1021/acsearthspacechem.2c00220
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发表时间：
2022-11-21
影响因子：
3.4
通讯作者：
Frossard, Amanda A.
中科院分区：
文献类型：
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作者：
Burdette, Tret C.;Bramblett, Rachel L.;Frossard, Amanda A.
表面活性物质存在于海水中，并可积聚在表层微层（SML）中。表面活性剂是两亲性有机化合物，可以降低界面的表面张力。目前的工作是研究SML中表面活性剂分子组成与地下水中表面活性剂分子组成之间的联系，以及不同水类型中表面活性剂分子组成的差异。在本研究中，在特拉华湾的三个地点（海湾口、中湾和受沼泽影响的布罗德基尔河）采集了三个采样日的地下水和SML样本。采用两种固相萃取法（石墨化碳和C18）从SML和地下水中提取有机物，然后采用张力测定法和高分辨率质谱法，在正电离和负电离模式下进行分析。在这里，我们发现与地下水相比，高H/C的分子在SML中优先富集。我们证明了测量的有机提取物有助于降低SML中的表面张力。降雨事件导致陆地径流和混合增加，改变了Broadkill河站点SML和地下水中有机分子的组成，并且提取的有机分子的组成在采样日之间发生变化。这些结果表明，表面活性剂的组成在采样区域之间或从地下到SML之间并不均匀。
Surface-active species are present in marine waters and can accumulate in the surface microlayer (SML). Surfactants are amphiphilic organic compounds that reduce surface tension at an interface. Current work is investigating the link between the molecular composition of surfactants in the SML and those in subsurface waters, as well as the differences in surfactant molecular composition across different water types. In this study, subsurface water and SML samples were collected on three sampling days at three sites in the Delaware Bay: the Mouth of the Bay, Mid-Bay, and the marsh-influenced Broadkill River. Organic matter was extracted from the SML and subsurface water using two solid-phase extractions (graphitized carbon and C18) and then analyzed using tensiometry and high-resolution mass spectrometry, in positive and negative ionization modes. Here, we show that molecules with high H/C are preferentially enriched in the SML compared to the subsurface waters. We demonstrate that the measured organic extracts contribute to lower surface tensions in the SML. A rainfall event led to increased terrestrial runoff and mixing that altered the composition of the organic molecules in the SML and subsurface waters of the Broadkill River site, and the composition of the extracted organic molecules varied across sampling days. These results imply that the surfactant compositions are not uniform across sampling regions or from the subsurface to the SML.