中文摘要：

类异戊二烯甘油二烷基甘油四醚类化合物（isoGDGTs）是古菌微生物的特征脂类标志物,由这组化合物构造出的TEX86温标在海水古温度重建中得到了广泛应用。本文调查了珠江口及近岸海域（水深小于30m）4个季节水体悬浮颗粒物（SPM）的isoGDGTs分布情况。结果显示：虎门上游河流水体中的isoGDGTs主要来自原地生产的甲烷古菌输入,进入河口水体后,主要来自原地奇古菌和广古菌的输入。陆源古菌的输入在5月份和8月份,对河流水体产生一定的影响,但对河口水体的影响相对较小。珠江口水体isoGDGTs中的GDGT-2与GDGT-3比值（GDGT-[2]/[3]）和GDGT-Cren′的丰度百分比（Cren′%）分别小于4和4%,与南海深水沉积物明显不同,表明珠江口与南海深水沉积物中isoGDGTs的古菌来源存在差异,这也可能是引起珠江口水体TEX86温度（基于全球标定公式）偏离水体实际温度的原因。珠江口表层水体isoGDGTs中的GDGT-2和GDGT-3的丰度百分比与南海表层水体存在差异,这可能与GroupⅠ奇古菌和GroupⅡ广古菌相对比例空间变化有关。珠江口表层水体isoGDGTs的TEX86温度在2月份明显高于原地表层水体温,而其他月份都低于原地表层水体温度,可能与GroupⅠ奇古菌和GroupⅡ广古菌相对比例的季节变化有关。几个月份中11月份isoGDGTs绝对含量最高,8月份较低,表明11月份和8月份分别是原地古菌生产量较大和较小时期。统计分析的结果显示,水体铵根离子含量、水体温度,以及溶解氧水平可能是控制珠江口水体isoGDGTs分布的主要环境因素。

英文摘要：

Isoprenoid glycerol dialkyl glycerol tetraethers（isoGDGTs）are biomarkers of archaea.TEX86 is a sea surface temperature（SST）proxy based on the distribution of cyclic moieties of isoGDGTs and has been widely applied to reconstruct paleo-SST in numerous cases.In this study,the distributions of isoGDGTs from surface water suspened particulate matter（SPM）during the four seasons in Pearl River Estuary（PRE,water depth below 30m）and it′s coastal waters are reported.The results showed that the major sources of isoGDGTs are in situ Methanogen in freshwater,while in estuarine brackish water,the sources of isoGDGTs are in situ Thaumarchaeota and Euryarchaeota.The input of terrigenous isoGDGTs exerted an influence on freshwater in May and August,which was inconspicuous in the estuary.The ratio of GDGT-2to GDGT-3（GDGT-[2]/[3]）and fractional abundance of GDGT-Cren′（Cren′%）were less than 4and 4%,respectively,which are clearly different from those in surface sediments of deep basin of South China Sea（SCS）.This indicates that archaeal sources of isoGDGTs in the PRE are different from those in surface sediments of SCS,which may result in the deviation of TEX86-based temperatures from actual water temperatures in PRE.The variation in fractional abundance of GDGT-2and GDGT-3in surface water SPM of PRE and SCS may relate to the spatial changes in relative proportion in GroupⅠThaumarchaeota and GroupⅡEuryarchaeota.The TEX86-based temperatures of isoGDGTs were higher than actual surface water temperatures in February,whereas they were lower than actual surface water temperatures in other months in the PRE.This may be attributed to the seasonal variation of relative proportion in GroupⅠThaumarchaeota and GroupⅡEuryarchaeota.The isoGDGTs from surface water SPM of the PRE were most and least abundant in November and August,respectively,suggesting high and lowin situaquatic Archaeal production in the two months,respectively.Statistical analysis showed that water temperature,NH＋4and dissolved oxyge