Abstract：
A comprehensive understanding of carbon cycling pathways in the soil-plant system is needed to develop models that accurately predict global carbon reservoir responses to anthropogenic perturbations. Honey is a carbon-rich natural food produced by wild and managed pollinating insects all over the world; the composition of a single sample is a function of millions of pollinator-plant interactions. We studied the 13C/12C and Δ14C of 121 honey samples sourced from the United States, and found a significant older carbon contribution. The effect is observed from 25 to 45° latitude, not correlated with 13C/12C, and consistent with a previously published study on European honeys. In specific cases, the measured values were up to 20 ‰ (Δ14C) higher than the expected atmospheric 14CO2 value for the given year, which shows a significant older carbon contribution. We hypothesize that the older carbon is from plant liquids derived in part from soil carbon or stored nonstructural carbohydrates from plants, which shifts the calibrated age of the sample by 5 years or more. Our work is the first to describe the widespread occurrence of older carbon in honey and shows that radiocarbon measurements can be a powerful tool to trace carbon allocations in terrestrial food webs and detect the atmosphere-soil-plant carbon cycle contributions.
摘要：
需要全面了解土壤-植物系统中的碳循环途径，以开发能够准确预测全球碳库对人为扰动的响应的模型。蜂蜜是一种富含碳的天然食物，由世界各地的野生和管理授粉昆虫生产;单个样品的组成是数百万传粉者-植物相互作用的函数。我们研究了来自美国的121个蜂蜜样品的13C/12C和Δ14C，并发现了一个重要的旧碳贡献。从25到45°纬度观察到这种影响，与13C/12C不相关，与先前发表的关于欧洲蜂蜜的研究一致。在特定情况下,测量值比给定年份的预期大气14CO2值高20‰(Δ14C)，这表明了一个重要的旧碳贡献。我们假设较老的碳来自植物液体，部分来自土壤碳或植物储存的非结构性碳水化合物，这将样品的校准年龄移动了5年或更长时间。我们的工作是第一个描述蜂蜜中旧碳的广泛存在，并表明放射性碳测量可以成为追踪陆地食物网中碳分配和检测大气-土壤-植物碳循环贡献的强大工具。
