In contrast to aquatic food chains, knowledge of the origins and transfer of mercury (Hg) and methylmercury (MeHg) in terrestrial food chains is relatively limited, especially in songbirds. We collected soil, rice plants, aquatic and terrestrial invertebrates, small wild fish, and resident songbird feathers from an Hg-contaminated rice paddy ecosystem for an analysis of stable Hg isotopes to clarify the sources of Hg and its transfer in songbirds and their prey. Significant mass-dependent fractionation (MDF, δ²⁰²Hg), but no mass-independent fractionation (MIF, ∆¹⁹⁹Hg) occurred in the trophic transfers in terrestrial food chains. Piscivorous, granivorous, and frugivorous songbirds and aquatic invertebrates were all characterized by elevated Δ¹⁹⁹Hg values. The estimated MeHg isotopic compositions obtained using linear fitting and a binary mixing model explained both the terrestrial and aquatic origins of MeHg in the terrestrial food chains. We found that MeHg from aquatic habitats is an important subsidy for terrestrial songbirds, even those that feed mainly on seeds, fruits, or cereals. The results show that MIF of the MeHg isotope is a reliable tool to reveal MeHg sources in songbirds. Because the MeHg isotopic compositions was calculated with a binary mixing model or directly estimated from the high proportions of MeHg, compound-specific isotope analysis of Hg would be more useful for the interpretation of the Hg sources, and is highly recommended for future studies.

与水生食物链相比，关于汞 (Hg) 和甲基汞 (MeHg) 在陆地食物链中的起源和转移的知识相对有限，尤其是在鸣禽中。我们从受汞污染的稻田生态系统中收集了土壤、水稻植物、水生和陆生无脊椎动物、小型野生鱼类和栖息的鸣禽羽毛，用于分析稳定的汞同位素，以阐明汞的来源及其在鸣禽及其猎物中的转移。在陆地食物链的营养转移中没有发生显着的质量依赖性分馏（MDF，δ ²⁰² Hg），但没有发生质量无关的分馏（MIF，Δ199 ^{Hg ）。}食鱼、食谷和食果鸣禽和水生无脊椎动物都具有升高的 Δ ^199特征汞值。使用线性拟合和二元混合模型获得的估计甲基汞同位素组成解释了陆地食物链中甲基汞的陆地和水生来源。我们发现来自水生栖息地的甲基汞是陆生鸣禽的重要补贴，即使是那些主要以种子、水果或谷物为食的鸣禽也是如此。结果表明，甲基汞同位素的 MIF 是揭示鸣禽中甲基汞来源的可靠工具。由于 MeHg 同位素组成是使用二元混合模型计算的或直接从高比例的 MeHg 中估算的，因此 Hg 的特定化合物同位素分析对于解释 Hg 来源更有用，强烈推荐用于未来的研究。