Black carbon (BC) is a significant component of the global carbon cycle both in terrestrial and aquatic systems. Dissolved black carbon (DBC) is a significant portion of the total dissolved organic carbon (DOC) pool and represents a major flux of recalcitrant carbon to the coastal and deep oceans. Dissolved black carbon can originate from multiple sources related to its relative biogeochemical reactivity with the dynamics of highly recalcitrant DBC integral to long-term sequestration. Thus, understanding how the more recalcitrant fractions of DBC varies in diverse catchments is critical and currently underexplored. We used hydrogen pyrolysis to isolate the fraction of DBC with aromatic clusters above 7 rings, representing the more stable components. Here we report the dynamics of DBC_HyPy over a hydrological year in a temperate catchment, with a long history of coal mining extraction. Quarterly measurements of DBC were undertaken from two main channel and four tributary sites. Hydrogen pyrolysis derived DBC comprised a significant percentage of the total DOC flux (3.2% to 28.3%) and included significant spatial variability. Unlike other studies examining more reactive DBC fractions, bulk DOC concentrations and DBC_HyPy were poorly correlated when considered over an annual scale. Rather, DBC_HyPy was correlated with indicators of groundwater such as dissolved inorganic carbon and conductivity. Data suggest a consistent source of DBC_HyPy not subject to the same mobilisation drivers as DOC, which shows substantial seasonality. Rather, our data shows a potentially consistent supply of stable DBC originating from the coal mining-influenced groundwater. Petrogenic sources of DBC have been poorly constrained to date, the data presented here suggests in some catchments it may be significant and yield catchment scale DOC-DBC decoupling. The dynamics of DBC have implications for carbon fluxes, pollution transport and water quality/treatment requirements. These preliminary findings suggest potentially complex drivers in spatially heterogeneous catchments, contrasting with previous work finding tight DOC-DBC mobilisation dynamics.

黑碳（BC）是陆地和水生系统中全球碳循环的重要组成部分。溶解黑碳 (DBC) 是总溶解有机碳 (DOC) 库的重要组成部分，代表了流向沿海和深海的顽固碳的主要通量。溶解的黑碳可能源自与其相对生物地球化学反应性相关的多种来源，以及高度顽固的 DBC 动态，是长期封存的一部分。因此，了解 DBC 中更顽固的部分如何在不同流域中变化至关重要，但目前尚未得到充分探索。我们利用氢热解分离出具有 7 环以上芳香族簇的 DBC 部分，代表更稳定的组分。在这里，我们报告了温带流域一个水文年中 DBC _HyPy的动态，该流域具有悠久的煤炭开采历史。每季度对两个主河道和四个支流地点进行 DBC 测量。氢热解衍生的 DBC 占总 DOC 通量的很大一部分（3.2% 至 28.3%），并且具有显着的空间变异性。与其他研究更具反应性的 DBC 分数的研究不同，在年度范围内考虑时，散装 DOC 浓度和 DBC _HyPy相关性很差。相反，DBC _HyPy与地下水指标（例如溶解的无机碳和电导率）相关。数据表明，DBC _HyPy的来源一致，不受与 DOC 相同的动员驱动因素的影响，这显示出很大的季节性。相反，我们的数据显示，受煤矿开采影响的地下水可能存在稳定的 DBC 供应。 迄今为止，DBC 的岩石来源受到的限制很少，此处提供的数据表明，在某些流域中，它可能是显着的，并且流域产量规模 DOC-DBC 脱钩。 DBC 的动态对碳通量、污染物传输和水质/处理要求有影响。这些初步研究结果表明，空间异质流域中存在潜在复杂的驱动因素，与之前发现严格的 DOC-DBC 动员动态的工作形成鲜明对比。