Capping with layers of inert or adsorptive materials is used to control the release of polycyclic aromatic hydrocarbons (PAH) in sediment but little is known about microbial degradation processes in these materials. A rich native microbial community inhabits the sediment bed, and capping media can influence enrichment and biodegradation activity of benthic microorganisms. The aim of this study was to evaluate the effects of capping media (sand, organoclay, and powdered activated carbon [PAC]) on microbial communities under oxic conditions typical of the cap–water interface, where naphthalene degradation (model PAH) is likely to be maximized. Bench scale experiments compared naphthalene concentrations, nahAc biomarker abundance, microbial community composition, and cellular attachment in systems amended with adsorptive and non-adsorptive capping materials. Results indicate that activated carbon promoted and enhanced bioactivity; PAC treatments showed high biodegradation rates, nahAc biomarker levels, and attached biological growth consistent with enrichment of the PAH-degrading genus Pseudomonae. In contrast, sand did not enhance biological activity compared to media-free systems. Naphthalene strongly influenced microbial community composition at the species level in all treatments except organoclay, which promoted biological signatures commonly associated with impeding degradation activity. Data overall suggest that adsorptive capping materials can both promote (PAC) and inhibit (organoclay) bioactivity in the surficial layer of caps, indicating that media selection is critical to the design of bioactive capping systems.

用惰性或吸附性材料层覆盖来控制沉积物中多环芳烃（PAH）的释放，但对于这些材料中的微生物降解过程知之甚少。沉积层中有丰富的原生微生物群落，加盖培养基会影响底栖微生物的富集和生物降解活性。这项研究的目的是评估在帽盖水界面典型的有氧条件下，萘降解（PAH型）可能会造成氧化的条件下，加帽介质（砂，有机粘土和粉状活性炭[PAC]）对微生物群落的影响。被最大化。基准规模实验比较了萘浓度，nahAc生物标志物的丰度，微生物群落组成和细胞附着在使用吸附性和非吸附性封端材料进行了修改的系统中。结果表明，活性炭促进并增强了生物活性。PAC处理显示出高生物降解率，nahAc生物标志物水平以及附着的生物生长，与PAH降解假单胞菌属的富集一致。相反，与无介质系统相比，沙子没有增强生物活性。萘在除有机粘土外的所有处理中都在物种层面上强烈影响微生物群落组成，有机粘土可促进通常与阻碍降解活性相关的生物特征。总体数据表明，吸附性封盖材料可以在封盖的表层同时促进（PAC）和抑制（有机粘土）生物活性，表明介质的选择对于生物活性封盖系统的设计至关重要。