Atmospheric deposition of semivolatile aromatic hydrocarbons accounts for an important input of organic matter to the surface ocean. Nevertheless, the biogeochemical cycling and sinks of semivolatile aromatic hydrocarbons in the ocean remain largely uncharacterized. Here we present measurements of 64 polycyclic aromatic hydrocarbons in plankton and seawater from the Atlantic, Pacific, Indian and Southern Oceans, as well an assessment of their microbial degradation genes. Concentrations of the more hydrophobic compounds decreased when the plankton biomass was higher, consistent with the relevance of the biological pump. The mass balance for the global oceans showed that the settling fluxes of aromatic hydrocarbons in the water column were two orders of magnitude lower than the atmospheric deposition fluxes. This imbalance was high for low molecular weight hydrocarbons, such as phenanthrene and methylphenanthrenes, highly abundant in the dissolved phase. Parent polycyclic aromatic hydrocarbons were depleted to a higher degree than alkylated polycyclic aromatic hydrocarbons, and the degradation genes for polycyclic aromatic hydrocarbons were found to be ubiquitous in oceanic metagenomes. These observations point to a key role of biodegradation in depleting the bioavailable dissolved hydrocarbons and to the microbial degradation of atmospheric inputs of organic matter as a relevant process for the marine carbon cycle.

半挥发性芳香烃在大气中的沉积是海洋表层有机物的重要输入。但是，海洋中的生物地球化学循环和半挥发性芳香烃的汇聚仍未得到充分表征。在这里，我们介绍了来自大西洋，太平洋，印度洋和南洋的浮游生物和海水中64种多环芳烃的测量值，以及它们的微生物降解基因的评估。当浮游生物的生物量较高时，疏水性更高的化合物的浓度降低，这与生物泵的相关性一致。全球海洋的质量平衡表明，水柱中芳烃的沉降通量比大气沉降通量低两个数量级。对于在溶解相中高度丰富的低分子量碳氢化合物（例如菲和甲基菲），这种不平衡性很高。母体多环芳烃的耗竭程度高于烷基化多环芳烃，并且发现多环芳烃的降解基因在海洋基因组中普遍存在。这些观察结果表明，生物降解在消耗可生物利用的溶解碳氢化合物方面起着关键作用，并指出大气中有机物输入的微生物降解是海洋碳循环的一个相关过程。并且发现多环芳烃的降解基因在海洋基因组中普遍存在。这些观察结果表明，生物降解在消耗可生物利用的溶解碳氢化合物方面起着关键作用，并指出大气中有机物输入的微生物降解是海洋碳循环的一个相关过程。并且发现多环芳烃的降解基因在海洋基因组中普遍存在。这些观察结果表明，生物降解在消耗可生物利用的溶解碳氢化合物方面起着关键作用，并指出大气中有机物输入的微生物降解是海洋碳循环的一个相关过程。