Abstract：
Herein, we investigated the trophic transfer of mercury (Hg) through food chains in different habitats (namely aquatic, riparian, and terrestrial) through bulk stable isotope analysis of nitrogen (δ15Nbulk) and compound-specific isotope analysis of nitrogen in amino acids (δ15NAA) using bird feathers and their potential food sources from a Hg-contaminated site in southwest China. Results showed similar δ15Nphe for water birds (4.7 ± 2.6 ‰) and aquatic food sources (5.2 ± 2.1 ‰) and for land-based food sources (10.1 ± 0.4 ‰) and terrestrial birds (11.6 ± 3.0 ‰), verifying δ15Nphe as a potential discriminant indicator for different food sources. The trophic positions (TPs) of most organisms based on δ15Nbulk (TPbulk) tended to overestimate compared with those based on δ15NAA (TPAA), especially for predators (such as kingfisher: ΔTP = 1.3). Additionally, significant differences were observed in the aquatic, riparian, and terrestrial food webs between trophic magnification slope (TMS)bulk and TMSAA (p < 0.05). The trophic magnification factor (TMF)AA-multiple based on multiple-AAs in three food webs were higher than the TMFAA and TMFbulk, probably because of the greater variation of δ15Nbaseline, complex food sources or the notably different in individual organisms. Altogether, our results improve the understanding of Hg trophic transfer in aquatic, riparian, and terrestrial food webs.
摘要：
在这里，我们调查了汞(Hg)通过食物链在不同生境(即水生，河岸,和陆地）通过使用鸟类羽毛及其来自中国西南部汞污染地点的潜在食物来源，对氮进行大量稳定同位素分析（δ15Nbulk）和氨基酸中的氮进行化合物特异性同位素分析（δ15NAA）。结果表明，水鸟（4.7±2.6‰）和水生食物来源（5.2±2.1‰）以及陆基食物来源（10.1±0.4‰）和陆生鸟类（11.6±3.0‰）的δ15Nphe相似，验证δ15Nphe作为不同食物来源的潜在判别指标。与基于δ15NAA（TPAA）的大多数生物相比，基于δ15Nbulk（TPbulk）的大多数生物的营养位置（TP）倾向于高估，特别是对于捕食者(如翠鸟:ΔTP=1.3)。此外,在水生生物中观察到显著差异，河岸,营养放大斜率（TMS）体积和TMSAA之间的陆地食物网（p<0.05）。三个食物网中基于多个AA的营养放大因子（TMF）AA倍数高于TMFAA和TMFbulk，可能是因为δ15N基线的变化更大，复杂的食物来源或个体生物的显著不同。总之,我们的结果提高了对水生汞营养转移的理解，河岸,和陆地食物网。
