Occurrence and distribution of hydroxylated isoprenoid glycerol dialkyl glycerol tetraethers(OH-GDGTs) in the Han River system, South Korea

We investigated the occurrence and distribution of terrestrial-derived hydroxylated isoprenoid glycerol dialkyl glycerol tetraethers(OH-GDGTs) in the Han River system and their potential impact on the application of the ring index of OH-GDGTs(RI-OH) as a sea surface temperature(SST) proxy in the eastern Yellow Sea. Thereby, we analyzed various samples collected along the Han River and from its surrounding areas(South Korea, n = 34). The OHGDGTs were found in all samples investigated. OH-GDGT-0 was the dominant OH-GDGT component in the estuary and marine samples while OH-GDGT-2 was generally dominant in the soils, the lake sediments and the river suspended particulate matter(SPM). Our results thus suggests a possible warm bias of the RI-OH-derived summer SSTs in the coastal zone to which a large amount of terrestrial organic matter is being supplied. Further studies are necessary to better assess the applicability of the RI-OH proxy in the eastern Yellow Sea.

青海湖钻孔沉积物中的羟基甘油二烷基甘油四醚类化合物及其环境意义

来源于古菌细胞膜脂的类异戊二烯甘油二烷基甘油四醚类化合物（isoGDGTs）是古环境重建的有力工具。最近的研究发现，自然环境中还存在着一类isoGDGTs烷基长链上含有羟基的OH—GDGTs，其相对含量与温度负相关，具有示踪古温度的潜力。然而，目前湖相环境中关于OH—GDGTs的研究还很少。我们通过高效液相色谱-大气压化学电离-质谱分析，在青海湖8ka以来沉积物中检测到了OH—GDGTs的存在，其含量（相对含量％OH—GDGTs及浓度）与奇古菌特征标志物crenarchaeol相对含量和奇古菌amoA基因丰度一致，表明青海湖中的OH—GDGTs可能主要来源于奇古菌。进一步与湖泊水位指标对比显示，青海湖中％OH—GDGTs的变化可能主要反映了湖水深度变化导致的古菌群落的变化。因此，认为湖泊沉积物中的OH—GDGTs可指示古水文条件变化。