Global change pattern of sedimentary nitrogen isotope during the Anthropocene epoch

Nitrogen (N) cycling has been reshaped during the Anthropocene epoch, yet the global change pattern of sedimentary N stable isotope (δ15N) remains unclear. Previous research has mainly focused on changes of sedimentary δ15N in remote areas or during the Holocene epoch, yet the differentiation of sedimentary δ15N between remote areas and disturbed regions and the onset of the differentiation time are neglected in the Anthropocene epoch. Here we synthesized published records of well-dated δ15N abundance in sedimentary sequences from 173 sites globally, including natural and disturbed areas, and proposed a conceptual diagram to descript the global change patterns of sedimentary δ15N in past 300 years. Sedimentary δ15N in disturbed sites enriched, with two breakpoints in 1910s and 1950s. The other one, δ15N trend in natural sites mostly depleted, with a breakpoint in 1920s. The timeline aligns with unprecedented anthropic perturbations to the global N cycle, such as the invention and application of the Haber-Bosch process. The divergence of δ15N change pattern between disturbed and natural areas can be attributed to either direct human activities or indirect consequences. Taken together, we propose that the 1910s − 1930s can be considered the precursor of the Anthropocene due to the application of artificial N fixation and its consequent biogeochemical effect. We emphasize that the Haber-Bosch process could be the important event before the impact of human activities on Earth history is reflected in global stratigraphy. The timeline between 1910-1930 caused unprecedented anthropogenic perturbations to the global nitrogen cycle, which attributed to the invention and application of the Haber-Bosch process, according to a global meta-analysis of sedimentary nitrogen stable isotope from 173 sites.