Table 1 Concentrations, δ13C values, and typical indices based on n-alkanes in the subsamples with different sediment depth of core R23. The relative contribution of long chain n-alkanes from C3 and C4 plants are calculated by carbon isotopes of the C31 n-alkane
Depth (cm) | δ13C23 (‰) | δ13C24 (‰) | δ13C25 (‰) | δ13C26 (‰) | δ13C27 (‰) | δ13C28 (‰) | δ13C29 (‰) | δ13C31 (‰) | n-alkanesa (ng/g) | C4 (%) | C3 (%) | ACLb | CPIc |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
16 | −29.6 | −28.8 | −29.9 | −33.2 | −28.5 | −32.2 | −27.4 | −28.3 | 445 | 55 | 45 | 30.1 | 1.6 |
88 | −29.5 | −31.8 | −27.3 | −30.0 | −26.3 | −33.1 | −25.1 | −25.5 | 328 | 75 | 25 | 30.3 | 2.0 |
166 | −25.4 | −26.4 | −26.7 | −32.5 | −28.3 | −38.0 | −27.1 | −27.8 | 295 | 59 | 41 | 30.1 | 2.1 |
243 | −27.1 | −26.8 | −26.8 | −30.4 | −26.7 | −33.3 | −29.8 | −28.3 | 362 | 55 | 45 | 30.3 | 2.5 |
323 | −29.8 | −31.2 | −30.6 | −35.0 | −28.3 | −32.1 | −29.4 | −27.9 | 324 | 58 | 42 | 29.3 | 1.3 |
398 | −31.5 | −35.9 | −30.0 | −36.7 | −28.6 | −34.6 | −25.0 | −24.8 | 787 | 80 | 20 | 29.6 | 1.3 |
482 | −26.8 | −28.4 | −29.3 | −30.3 | −26.8 | −30.1 | −27.4 | −26.6 | 411 | 67 | 33 | 30.7 | 1.9 |
550 | −27.1 | −30.7 | −29.3 | −35.1 | −27.8 | −31.2 | −27.8 | −25.4 | 420 | 76 | 24 | 30.1 | 1.6 |
626 | −30.4 | −32.2 | −31.7 | −34.6 | −29.6 | −30.9 | −26.4 | −25.8 | 344 | 73 | 27 | 29.6 | 1.6 |
698 | −28.6 | −30.6 | −29.0 | −32.7 | −27.8 | −31.8 | −27.0 | −25.8 | 490 | 73 | 27 | 29.3 | 1.1 |
762 | −28.8 | −29.3 | −30.0 | −35.3 | −26.7 | −32.1 | −30.4 | −29.4 | 455 | 47 | 53 | 29.8 | 1.6 |
818 | −28.8 | −28.7 | −32.3 | −37.4 | −30.1 | −35.8 | −27.7 | −27.2 | 503 | 63 | 37 | 30.1 | 1.7 |