Evaluating the Influence of Salinity on Lipid D/H Fractionation in Saline Lakes

地质历史中的盐度变化很难重建，但对于理解气候，海洋环流，进化生物学和地质记录中的碳储存非常重要。为了开发一种新的水盐度指标，我们将建立在最近的实验结果的基础上，这些实验结果表明，藻类脂质中的氢同位素分馏随着盐度的增加而减少。Schouten等人（2006年）最近的一份报告指出，盐度改变了培养的颗石藻类藻类脂质中的氢同位素分馏，以及这一发现为古盐度和古水文重建带来的前景，研究人员建议测试盐度对各种藻类中脂质D/H分馏的影响的普遍性，微生物和古菌脂质在各种各样的天然盐水系统与盐度之间的0.4 - 277 ppt。 他们在圣诞岛和切萨皮克湾的初步结果支持了Schouten等人（2006年）的假设，即藻类和微生物脂质中的D/H分馏随盐度增加而降低。在圣诞岛，他们发现在盐度范围17 - 149 ppt的几种藻类和细菌生物标志物和总脂质提取物中，盐度和脂质D/H分馏之间存在很强的负相关性。在切萨皮克湾，他们观察到一个很强的盐度和D/H分馏的甲藻脂dinosterol在盐度之间的反比关系8 - 31 ppt。拟议的研究将使用水，颗粒和表面沉积物样品从39个全球分散在加拿大，美国，玻利维亚，以色列，南非，哈萨克斯坦，和加拉帕戈斯群岛的含盐盆地。这一系列高度多样化的湖泊被选择来跨越尽可能广泛的盐度、湖沼学、水化学和气候。他们将测量来自藻类的几种不同脂质生物标志物的D值（例如，地甾醇，高度支化的类异戊二烯烯烃，岩藻黄素，葡萄球菌），细菌（例如，dipoptene，hopanoids，细菌叶绿素a-e）和古菌（甘油-二烷基-甘油-四醚）在悬浮颗粒和表层沉积物中的每个湖泊，并比较这些值的湖水的D值。更广泛的影响：该项目将支持一名女研究生，并促进对本科生和高中生的环境研究教育。在11名实验室成员中，5名是女性，4名是本科生，1名是高中生。2007年6月，两名大学生沿着PI进行了实地考察，为该项目收集了盐湖样本。他们的网站描述他们的研究收到超过700点击每天。在过去的8年里，PI在6次全国高中科学竞赛中担任科学评委。这些活动将继续使学生和公众接触最前沿的环境研究。

Salinity variations in the geologic past are difficult to reconstruct, yet important for understanding climate, ocean circulation, evolutionary biology, and carbon storage in the geologic record. In an effort to develop a new indicator of water salinity we will build on recent experimental results indicating that hydrogen isotope fractionation in algal lipids decreases as salinity increases.Intellectual Merit: Motivated by a recent report by Schouten et al. (2006) that salinity altered hydrogen isotope fractionation in lipids from cultured coccolithophorid algae, and the prospect this finding raises for paleosalinity and paleohydrologic reconstructions, investigators propose to test the generality of a salinity influence on lipid D/H fractionation in a variety of algal, microbial and archaeal lipids in a wide diversity of natural saline systems with salinities between 0.4 - 277 ppt. Their initial results from Christmas Island and the Chesapeake Bay support the hypothesis of Schouten et al. (2006) that D/H fractionation in algal and microbial lipids decreases with increasing salinity. At Christmas Island they find a strong inverse correlation between salinity and lipid D/H fractionation in several algal and bacterial biomarkers and total lipid extracts over the salinity range 17 - 149 ppt . In the Chesapeake Bay they observe a strong inverse relationship between salinity and D/H fractionation in the dinoflagellate lipid dinosterol at salinities between 8 - 31 ppt.The proposed study will use water, particulate and surface sediment samples from 39 globally dispersed saline basins in Canada, the USA, Bolivia, Israel, South Africa, Kazhakstan, and the Galapagos Islands. This highly diverse set of lakes was chosen to span the widest possible range of salinities, limnologies, water chemistries, and climates. They will measure the δD values of several different lipid biomarkers from algae (e.g., dinosterol, highly branched isoprenoid alkenes, fucoxanthin, botryococcenes), bacteria (e.g., diploptene, hopanoids, bacteriochlorophyll a-e) and archaea (glycerol-dialkyl-glycerol-tetraethers) in suspended particles and surface sediments in each lake, and compare those values to the δD values of lake water. They possess all samples for this study.Broader Impacts: This project will support a female graduate student and facilitate the education of undergraduate and high school students in environmental research. Of 11 lab members, 5 are women, 4 are undergraduates and 1 is in high school. Two undergraduates, along with the PI, conducted the fieldwork to collect the saline lake samples for this project in June 2007. Their website describing their research receives over 700 hits per day. And the PI has been a science judge in 6 national high school science competitions during the last 8 years. These activities will continue to expose students and the public to cutting-edge environmental research.