LAUSR

Abstract Lake water salinity, an important indicator of lake hydrological conditions, is critical to deciphering terrestrial paleoclimatic and paleoenvironmental changes. The proportion of C37:4 alkenone to total C37 alkenones (%C37:4) and the relative abundance of archaeol to caldarchaeol (ACE) are promising salinity indices in lacustrine settings. Developing regional calibrations for both indicators is challenging due to limited datasets and a poor understanding of the factors that influence them. Here we present %C37:4 and ACE data collected from 55 lakes in mid-latitude Asia with a wide salinity range, to evaluate how well the two proxies can be correlated with salinity and to infer potential influencing factors. The %C37:4 values only show a weak negative correlation with salinity from all investigated lakes. The occurrence of C37:3 alkenone isomer and abnormal values in the alkenone C37/C38 ratio might signal species shifts or environmental factors that compromise the %C37:4-salinity relationship in our data set. Seasonal bias in alkenone production could further obscure this %C37:4-salinity relationship. A stronger relationship emerges after removing samples influenced by these factors: %C37:4 = − 8.56 ⁎ log 10 (salinity) + 80.6, r 2 = 0.62 , n = 37 ; or %C37:4 = − 13.46 ⁎ log 10 (salinity) + 101.48, with uncertainty in both variables considered. The ACE values show a strong positive correlation with salinity from all investigated lakes: ACE = 2.27 ⁎ 10 − 4 ⁎ salinity + 25.4 , r 2 = 0.75 , n = 68 ; or ACE = 1.86 ⁎ 10 − 4 ⁎ salinity + 38.1 , with uncertainty in both variables considered. However, substantial deviations of the ACE values in low salinity range (