Urbanization along coastlines alters marine ecosystems including contributing molecules of anthropogenic origin to the coastal dissolved organic matter (DOM) pool. A broad assessment of the nature and extent of anthropogenic impacts on coastal ecosystems is urgently needed to inform regulatory guidelines and ecosystem management. Recently, non-targeted tandem mass spectrometry approaches are gaining momentum for the analysis of global organic matter chemotypes including a wide array of natural and anthropogenic compounds. In line with these efforts, we developed a nontargeted liquid chromatography tandem mass spectrometry workflow that utilizes advanced data analysis approaches such as feature-based molecular networking and repository-scale spectrum searches. This workflow allows the scalable comparison and mapping of seawater chemotypes from large-scale spatial surveys as well as molecular family level annotation of unknown compounds. As a case study, we visualized organic matter chemotype shifts in coastal environments in northern San Diego, USA, after significant rain fall in winter 2017/2018 and highlight potential anthropogenic impacts. The observed seawater chemotype shifted significantly after a major rain event. Molecular drivers of this shift could be attributed to multiple anthropogenic compounds, including pesticides (Imazapyr and Isoxaben), cleaning products (Benzyl-tetradecyl-dimethylammonium) and chemical additives (Hexa(methoxymethyl)melamine) and potential degradation products. By expanding the search of identified xenobiotics to other public tandem mass spectrometry datasets, we further contextualized their possible origin and show their importance in other ecosystems. The mass spectrometry and data analysis pipelines applied here offer a scalable framework for future molecular mapping and monitoring of marine ecosystems, which will contribute to a deliberate assessment of how chemical pollution impacts our oceans. HIGHLIGHTS Feature-based Molecular Networking enables large-scale analysis of marine DOM Organic matter chemotype in coastal San Diego shifted significantly after rain Molecular drivers could be attributed to multiple anthropogenic compounds Spatial mapping highlighted different point sources as potential origin Repository-scale meta-analysis can further contextualize origin and importance 2
This study characterized emissions from IQOS, a heated tobacco product promoted as a less harmful alternative to cigarettes. Consumable tobacco plugs were analyzed by headspace GC/MS to assess the influence of heating temperature on the emission profile. Yields of major chemical constituents increased from 4.1 mg per unit at 180°C to 6.2 mg at 200 °C, and 10.5 mg at 220 °C. The Health Canada Intense smoking regime was used to operate IQOS in an environmental chamber, quantifying 33 volatile organic compounds in mainstream and sidestream emissions. Aldehydes, nitrogenated species, and aromatic species were found, along with other harmful and potentially harmful compounds. Compared with combustion cigarettes, IQOS yields were in most cases 1−2 orders of magnitude lower. However, yields were closer to, and sometimes higher than electronic cigarettes. Predicted users' daily average intake of benzene, formaldehyde, acetaldehyde and acrolein were 39 μg, 32 μg, 2.2 mg and 71 μg, respectively. Indoor air concentrations were estimated for commonly encountered scenarios, with acrolein levels of concern (over 0.35 μg m −3) derived from IQOS used in homes and public spaces. Heated tobacco products are a weaker indoor pollution source than conventional cigarettes, but their impacts are neither negligible nor yet fully understood.
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