Sources of Oxygenated Polycyclic Aromatic Hydrocarbons (OPAHs) in soils – a compound-specific stable isotope approach

含氧多环芳烃(OPAs)可在有机物燃烧或母体多环芳烃在环境中的二次转化过程中产生。几种奥帕在土壤中表现出比它们的母体多环芳烃更高的毒性、生物利用度和移动性。要评估多环芳烃和鸦片油污染产生的环境风险，需要了解鸦片油的生产情况。因此，有必要区分OPHs的初级(即燃烧来源)、次级光化学来源和次级微生物来源，并提高我们对土壤中多环芳烃向OPHA转化的理解。我们的目标是提供一种新的稳定的基于同位素比率的工具来区分气溶胶和土壤中的opah来源，以母体化合物-衍生物对菲(ANTH)和9，10-蒽醌(9，10-AQ)为例，后者是最常见的opah。我们将检验五个假设：(I)借助化合物特有的碳和氢同位素比率(d13C和d2h值)可以区分初级和次级9，10-AQ。(Ii)光化学产生的9，10-AQ显示特定的2H值。(3)3种来源(初级、次级光化学、次级微生物)的9，10-AQ的d13C和d2h值的差异允许三端元混合模型的解。(4)生物产生的9，10-AQ的贡献随着土壤微生物活性的增加而增加，光化学产生的9，10-AQ在农村土壤中的贡献高于城市土壤。(V)当土壤微生物中毒时，母体多环芳烃在培养过程中不会产生opahs。为了验证这五个假设，我们将实现三个工作包(WPS)。每个WP包括一个实验部分和一个观测部分。在第一个WP中，我们将Anth，Benz(A)P[B(A)P]的d13C和d2h值表征为完全由燃烧衍生的多环芳烃和9，10-AQ在大气中的总悬浮粒子(TSP)来自一次排放(生物质和化石燃料的燃烧)。在第二个WP中，我们将测定大气中光化学次生形成的9，10-AQ的d13C和d2H值，而第三个WP中的D13C和D2H值来自土壤中微生物的次生转化。收集生物质和化石燃料燃烧试验排放和城乡大气中的TSP。我们将把吸附在淤泥状气溶胶中的Anth暴露在玻璃球中的太阳辐射下。此外，我们还将在农村土壤中进行微生物周转实验，ANTH将被添加到这些土壤中。我们将研究Anth、B(A)P和9，10-AQ在多环芳烃微生物周转随深度递增的现代类型森林有机层中的垂直分布和化合物特定d13C和d2h值。在所有TSP和土壤样品中，我们将测定多环芳烃和有机磷的浓度，以及ANTH、9，10-AQ和部分B(A)P的化合物特定d13C和d2H值。

Oxygenated polycyclic aromatic hydrocarbons (OPAHs) can be produced during combustion of organic materials or secondary transformations of parent-PAHs in the environment. Several OPAHs show a higher toxicity, bioavailability, and mobility in soil than their parent-PAHs. To assess the environmental risk arising from PAH and OPAH contamination requires the understanding of the production of OPAHs. Thus, there is a need to distinguish the primary (i.e., combustion-derived), secondary photochemical, and secondary microbial sources of OPAHs and to improve our understanding of the transformation of PAHs to OPAHs in soils. We aim to provide a novel stable isotope ratio-based tool to distinguish between the OPAH sources in aerosol and soil at the example of the parent compound-derivative pair anthracene (ANTH) and 9,10-anthraquinone (9,10-AQ), the frequently most abundant OPAH. We will test five hypotheses: (i) Primary and secondary 9,10-AQ can be distinguished with the help of their compound-specific C and H isotope ratios (d13C and d2H values). (ii) Photochemically produced 9,10-AQ shows a specific 2H value. (iii) The differences in the d13C and d2H values of 9,10-AQ from the three sources (primary, secondary photochemical, secondary microbial) allow for the solution of a three-end-member mixing model. (iv) The contribution of biologically produced 9,10-AQ increases with microbial activity in soil measured as CO2-evolution from plant-free microcosms and the contribution of photochemically produced 9,10-AQ is higher in rural than in urban soils. (v) When the soil microorganisms are poisoned, no OPAHs are produced from parent-PAHs during incubation. To test the five hypotheses, we will realize three work packages (WPs). Each WP includes an experimental and an observational component. In the first WP, we will characterize the d13C and d2H values of ANTH, benz(a)pyrene [B(A)P] as an entirely combustion-derived reference PAH and 9,10-AQ in the total in the atmosphere suspended particles (TSPs) from primary emissions (combustion of biomass and fossil fuels). In the second WP, we will determine d13C and d2H values of 9,10-AQ from photochemical secondary formation in the atmosphere and in the third WP from microbial secondary transformation in the soil. We will collect TSPs from the emissions of experimental biomass and fossil fuel combustion and from urban and rural atmosphere. We will expose ANTH sorbed to a muck aerosol to solar irradiation in glass spheres. Moreover, we will conduct microbial turnover experiments in microcosms with rural soils to which ANTH will be spiked. We will study the vertical distribution and compound-specific d13C and d2H values of ANTH, B(A)P, and 9,10-AQ in moder-type forest organic layers where the microbial turnover of PAHs progresses with depth. In all TSP and soil samples, we will determine PAH and OPAH concentrations and compound-specific d13C and d2H values of ANTH, 9,10-AQ, and partly also B(A)P.