Top predators are used as indicators of contaminant trends across space and time. However, signals are integrated over complex food webs, and variation in diet may confound such signals. Trophic position, assessed by bulk δ¹⁵N, is widely used to infer the variation in diet relevant to contamination, yet a single variable cannot completely describe complex food webs. Thus, we examined relationships across three aquatic systems varying from a single species to a small food web using bulk values from four isotopes and 21 amino acid-specific values. Because variation in baseline ('source') δ¹⁵N can confound estimates of trophic position , we calculated trophic position from the difference between δ¹⁵N_trophic (δ¹⁵N for amino acids that change with trophic position) and δ¹⁵N_source (δ¹⁵N for amino acids that do not change with trophic position). Across all three systems, variation in δ¹⁵N_source explained over half of the variation in bulk δ¹⁵N, and stable isotope values that reflected the base of the food web (δ¹³C, δ¹⁸O, δ³⁴S) predicted contaminants as well or better than δ¹⁵N—which was supported by a meta-analysis of other studies. In ospreys feeding in lakes, variation in δ¹⁵N_source across space created a spurious relationship between ΣDDT and apparent trophic position, and masked a relationship between ΣPCB and trophic position. In a seabird guild, changes in diet over time obscured temporal variation in contaminants over five decades. In Arctic fish and invertebrates, more accurate trophic magnification factors were calculated using δ¹⁵N_{trophic-source}. Thus, (1) using δ¹⁵N_{trophic-source}, instead of bulk δ¹⁵N, avoided incorrect conclusions and improved accuracy of trophic magnification factors necessary to assess risk to top predators; and (2) diet assessed with multiple spatial isotopes, rather than δ¹⁵N alone, was essential to understand patterns in contaminants across space, time and biological communities. Trophic position was most important for lipophilic ‘legacy’ contaminants (ΣDDT, ΣPCB) and habitat was most important for other contaminants (ΣPBDE, ΣPFAS, mercury). We argue that the use of amino acid-specific analysis of δ¹⁵N alongside ‘non-trophic’ isotopes should be a core feature of any study that examines the influence of trophic position on chemical pollution, as required for a chemical to be added to international conventions such as the Stockholm Convention.

顶级捕食者被用作跨时空污染物趋势的指标。但是，信号是通过复杂的食物网整合的，饮食中的变化可能会混淆此类信号。营养位置，通过本体δ评估¹⁵ N，被广泛用于推断有关污染饮食变化，但单个变量不能完全描述复杂食物链。因此，我们使用四种同位素的总值和21种氨基酸特异性值，研究了从单一物种到小型食物网的三个水生系统之间的关系。因为在基线（“源”）δ变化¹⁵ N能混淆营养位置的估计值，我们计算营养位置从δ之间的差¹⁵ Ñ_营养（δ ¹⁵N代表氨基酸与营养位置变化）和δ ¹⁵ Ñ_源（δ ¹⁵ N代表不与营养位置改变氨基酸）。在所有三种系统中，δ的变化¹⁵ Ñ_源解释在散装的变化的一半δ ¹⁵ N，并且反射的食物网的基部（δ稳定同位素值¹³ C，δ ¹⁸ O，δ ³⁴ S）预测的污染物一样好或好于δ ¹⁵ N-二其通过一个支撑元其他研究的分析用。在鱼鹰在湖泊摄食，变化δ ¹⁵ Ñ_源跨空间在ΣDDT和明显营养位置之间造成了虚假关系，并掩盖了ΣPCB与营养位置之间的关系。在一个海鸟行会中，随着时间的推移饮食结构的变化掩盖了五十年来污染物的时间变化。在北极鱼类和无脊椎动物，更准确的营养放大因子，使用计算出的δ ¹⁵ Ñ_营养源。因此，使用δ（1）¹⁵ ñ_营养源，代替散装δ ¹⁵ N，可以避免不正确的结论和改进的必要评估风险顶部捕食者营养放大因子准确性; 和（2）饮食评估与多个空间的同位素，而不是δ ¹⁵仅N元素对于了解跨空间，时间和生物群落的污染物的模式至关重要。营养位置对亲脂性“遗留”污染物（ΣDDT，ΣPCB）最重要，栖息地对其他污染物（ΣPBDE，ΣPFAS，汞）最重要。我们认为，使用的δ氨基酸特异性分析的¹⁵ Ñ旁边“非营养”同位素应该是检上化学污染营养位置的影响，因为所需的化学物质被加入到任何研究的核心功能国际公约，例如《斯德哥尔摩公约》。