Calibration of the U 37 K′ index of long-chain alkenones with the in-situ water temperature in Lake Qinghai in the Tibetan Plateau

Abstract

Long-chain alkenones (LCAs) can potentially be used as indicators to understand past variations in lacustrine environments. Previous research has suggested that the relationship between the temperature and the unsaturation index of LCAs should be calibrated individually, because of the possible variations in the alkenone-producing algal species in the lacustrine environment. In this work, we have calibrated U 3 K 7 ′ of water filter samples against the in-situ water temperature in Lake Qinghai, Tibetan Plateau. There are significant relationships between U 3 K 7 ′ and the water temperature, a non-linear relationship was derived. Because the U 3 ′ index of long-chain alkenones with the in-situ water temperature in

Large Holocene summer temperature oscillations and impact on the peopling of the northeastern Tibetan Plateau

“…We use computed from alkenones to reconstruct past temperature changes based on a transfer function combining data from lake water filters at Lake Qinghai and 11 lake surface sediments in the TP (Figure S2 and Table S1). Lake water filter samples were collected in June, July, and August 2010 [ Wang and Liu , ]. The Lake Qinghai water filters are limited by the range of water temperatures and show relatively large uncertainties ( R 2 = 0.55 ) [ Wang and Liu , ].…”

“…Wang and Liu [] found alkenones were most abundant during the summer months in Lake Qinghai; hence, we adopted summer lake water temperature for the calibration. Though and are both found to correlate to in situ temperature in the lake water [ Chu et al , ; Wang and Liu , ], we believe is a more reliable temperature indicator for lake water for several reasons. First, index demonstrates better correlation with summer temperatures for the transect of lake surface sediments spanning greater range of environmental gradient.…”

“…Lake water filter samples were collected in June, July, and August 2010 [Wang and Liu, 2012]. The Lake Qinghai water filters are limited by the range of water temperatures and show relatively large uncertainties (R 2 = 0.55) [Wang and Liu, 2012]. However, when combined with alkenone data from surface sediments of 11 regional lakes, we find a greatly improved correlation between U K 37 and lake water temperatures (T = 17.571 * U K 37 + 20.849; R 2 = 0.8059, Figure S2B).…”

“…In order to reconstruct temperature changes, we take advantage of the presence of alkenones in Lake Qinghai sediments [ Liu et al , ; Wang and Liu , ]. To establish the relationship between summer temperatures and alkenone unsaturation, we combine the published calibration from Lake Qinghai water filter samples [ Wang and Liu , ] with a new set of 11 lake surface sediment data we collected in 2011 (Figure S2 in the supporting information). The relationship between and lake water temperature ( = 0.05613 T –1.1781, r 2 = 0.8059, n = 26, p < 0.005, residual mean = 1.51) allows us to transfer our downcore data to summer temperature variations, as the alkenone producers are active in summer in lake Qinghai [ Wang and Liu , ].…”

Solar imprints on Asian inland moisture fluctuations over the last millennium

“…linear regression in both cultural and sedimentary based reconstruction of Chinese lakes(Chu et al, 2005;Sun et al, 2007;Wang and Liu, 2013), with high U…”