青藏高原干旱区湖泊正构烷烃氢同位素记录降水同位素
发布时间：2019-02-19 18:20
【摘要】：湖泊和海洋沉积物中正构烷烃氢同位素作为有潜力的古水文和古气候指标已经得到广泛应用,但是在干旱区由于蒸发强烈而严重影响正构烷烃氢同位素比值,因此其能否记录降水同位素变化受到质疑.本研究在青藏高原干旱区采集了21个湖泊表层沉积物(其中20个湖泊年平均降水量400 mm),发现其正构烷烃氢同位素(δD_(wax))与年均降水平均氢同位素(δD_(ann))呈现较强相关(r~2=0.84,P0.001),其与夏季降水平均氢同位素(δD_(sum))相关性更好(r~2=0.91,P0.001),说明降水是控制湖泊沉积物中正构烷烃氢同位素(δD_(wax))变化的主要因素,在干旱地区正构烷烃氢同位素(δD_(wax))仍然可以反映降水氢同位素(δD_p)信息.本研究中湖泊表层沉积物正构烷烃和降水之间的氢同位素表观分馏平均值(ε_(wax-p))为-113‰,较湿润地区偏正,可能是由于干旱区蒸发强烈引起.因此沉积正构烷烃氢同位素(δD_(wax))可以作为夏季降水平均氢同位素(δDp)的替代指标,记录夏季风强度和古水文变化.
[Abstract]:Hydrogen isotopes of n-alkanes in lakes and marine sediments have been widely used as potential paleohydrological and paleoclimatic indicators, but in arid areas, the hydrogen isotopic ratios of n-alkanes are seriously affected by strong evaporation. Therefore, its ability to record precipitation isotopic changes has been questioned. In this study, the surface sediments of 21 lakes were collected in the arid region of Qinghai-Xizang Plateau. The average annual precipitation of 20 lakes was 400 mm),. It is found that there is a strong correlation between 未 D _ (wax) and average annual precipitation hydrogen isotope (未 D _ (ann). It has a better correlation with the average hydrogen isotope (未 D _ (sum) of summer precipitation (r ~ (2 +) ~ (21) ~ (-1) P ~ (0.001), indicating that precipitation is the main factor controlling the variation of 未 D _ (wax) in lake sediments. The hydrogen isotope (未 D _ (wax) of normal alkane in arid area can still reflect the information of precipitation hydrogen isotope (未 D _ p). The average value of hydrogen isotope fractionation (蔚 _ (wax-p) between normal alkanes and precipitation in the surface sediments of lakes is -113 鈥，
本文编号：2426742
[Abstract]:Hydrogen isotopes of n-alkanes in lakes and marine sediments have been widely used as potential paleohydrological and paleoclimatic indicators, but in arid areas, the hydrogen isotopic ratios of n-alkanes are seriously affected by strong evaporation. Therefore, its ability to record precipitation isotopic changes has been questioned. In this study, the surface sediments of 21 lakes were collected in the arid region of Qinghai-Xizang Plateau. The average annual precipitation of 20 lakes was 400 mm),. It is found that there is a strong correlation between 未 D _ (wax) and average annual precipitation hydrogen isotope (未 D _ (ann). It has a better correlation with the average hydrogen isotope (未 D _ (sum) of summer precipitation (r ~ (2 +) ~ (21) ~ (-1) P ~ (0.001), indicating that precipitation is the main factor controlling the variation of 未 D _ (wax) in lake sediments. The hydrogen isotope (未 D _ (wax) of normal alkane in arid area can still reflect the information of precipitation hydrogen isotope (未 D _ p). The average value of hydrogen isotope fractionation (蔚 _ (wax-p) between normal alkanes and precipitation in the surface sediments of lakes is -113 鈥，
本文编号：2426742
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