A new insight into isotopic fractionation associated with decarboxylation in organisms: implications for amino acid isotope approaches in biogeoscience

Progress in Earth and Planetary Science

Table 2 Nitrogen and carbon isotopic discriminations on amino acids in the four combination samples

Consumer - diet combination	Δ (δconsumer − δdiet) value (‰)
	Phe		Val		Leu		Ile		Gly		Ala		Glu
	Mean	SD	Mean	SD	Mean	SD	Mean	SD	Mean	SD	Mean	SD	Mean	SD
Δδ¹⁵N (‰)
Sea sulg - Sponge*	0.5	0.3	4.8	0.6	3.0	0.6	5.6	0.4	1.6	0.6	5.5	0.6	7.9	0.3
Ladybug beetle - Aphid**	0.3	0.3	6.5	0.5	5.3	0.5	3.6	0.6	6.6	0.5	4.5	0.5	7.7	0.3
Green lacewing #1 - Fall armyworm ***	0.4	0.3	5.5	0.3	3.6	0.5	3.3	0.4	0.8	0.7	5.4	0.4	8.0	0.4
Green lacewing #2 - Green lacewing #1***	0.5	0.3	5.5	0.3	4.2	0.4	3.8	0.5	0.8	0.3	5.5	0.4	8.1	0.5
Δδ¹³C (‰)
Sea sulg - Sponge*	-0.3	0.8	0.0	0.7	0.4	0.7	0.4	0.9	11.9	0.6	3.9	0.4	3.5	0.5
Ladybug beetle - Aphid**	-0.5	0.8	-1.0	0.8	-1.0	0.9	-0.4	0.6	3.0	1.1	4.9	0.8	2.2	0.2
Green lacewing #1 - Fall armyworm ***	-0.6	1.1	-0.9	0.5	0.3	0.2	-0.2	0.6	17.3	0.5	2.8	0.3	1.0	0.2
Green lacewing #2 - Green lacewing #1 ***	0.2	1.1	0.3	0.9	-0.5	0.5	0.5	0.9	17.5	0.7	2.6	0.4	0.2	0.9

* SD represents 1σ propagation error for comparing 1σ of Sea slug (3 injections for 1 individual) and Sponge (3 injections for 1 aggregation)
** SD represents 1σ propagation error for comparing 1σ of Ladybug beetle (3 injections for 5 individuals) and Aphid (3 injections for 1 colony)
*** SD represents 1σ propagation error for comparing 1σ of consumer and diet (1 injections for 4 trophic groups)