發(fā)布時(shí)間：2019-02-19 18:20

【摘要】：湖泊和海洋沉積物中正構(gòu)烷烴氫同位素作為有潛力的古水文和古氣候指標(biāo)已經(jīng)得到廣泛應(yīng)用,但是在干旱區(qū)由于蒸發(fā)強(qiáng)烈而嚴(yán)重影響正構(gòu)烷烴氫同位素比值,因此其能否記錄降水同位素變化受到質(zhì)疑.本研究在青藏高原干旱區(qū)采集了21個(gè)湖泊表層沉積物(其中20個(gè)湖泊年平均降水量400 mm),發(fā)現(xiàn)其正構(gòu)烷烴氫同位素(δD_(wax))與年均降水平均氫同位素(δD_(ann))呈現(xiàn)較強(qiáng)相關(guān)(r~2=0.84,P0.001),其與夏季降水平均氫同位素(δD_(sum))相關(guān)性更好(r~2=0.91,P0.001),說(shuō)明降水是控制湖泊沉積物中正構(gòu)烷烴氫同位素(δD_(wax))變化的主要因素,在干旱地區(qū)正構(gòu)烷烴氫同位素(δD_(wax))仍然可以反映降水氫同位素(δD_p)信息.本研究中湖泊表層沉積物正構(gòu)烷烴和降水之間的氫同位素表觀分餾平均值(ε_(tái)(wax-p))為-113‰,較濕潤(rùn)地區(qū)偏正,可能是由于干旱區(qū)蒸發(fā)強(qiáng)烈引起.因此沉積正構(gòu)烷烴氫同位素(δD_(wax))可以作為夏季降水平均氫同位素(δDp)的替代指標(biāo),記錄夏季風(fēng)強(qiáng)度和古水文變化.
[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，

本文編號(hào)：2426742