COLLABORATIVE RESEARCH: An 18 O Paleotemperature Curve for the North Atlantic for the Last 1000 Years, From Annual Growth Bands of the Bivalve Arctica islandica

9713547魏德曼这项研究将产生北大西洋北部过去1000年的海洋温度记录，这项研究基于对长寿的北极岛双壳类年生长带的稳定氧同位素分析。来自约500-1000年B.P.的谱带将通过放射性碳分析确定年龄，而那些来自100-500年B.P.的谱带将通过天冬氨酸外消旋来确定年龄，这将提供比放射性碳显著更好的精度。过去100年的年度18O记录已经从现场收集的北极(魏德曼和琼斯在准备中)被创造出来。这项研究将使用从南塔基特浅滩地区表层沉积物中挖出的亚化石贝壳进行。这个外部大陆架区域足够浅，可以提供上层海洋水域的温度记录，但离海岸足够远，不受大陆淡水输入的影响。该地点的另一个特点是，它是从前南塔基特光船上获得的特别长的温度仪器记录的所在地，目前是美国国家海洋和大气局的长期天气监测点。将选择一个约25个贝壳的时间序列进行分析，这些贝壳跨越相关的年龄范围，每个贝壳包含50年的增长记录。这项研究的第二个主要目标是评估个体之间带宽变化的交叉匹配，以构建类似于树木年轮序列的年度时间序列。这有可能产生近几个世纪以来北大西洋环境变化的连续年度记录。与陆地环境相比，对海洋环境的长时间(100年)高分辨率记录是罕见的，在高纬度海洋地区基本上没有。由于缺乏合适的海洋温度记录，限制了我们对大气和海洋气候变化之间联系的理解。这些信息对于理解最近气候变化的性质和原因至关重要。其中包括从陆地记录中记录的中世纪暖期、小冰期和20世纪变暖趋势的长期(世纪尺度)变化，以及北大西洋涛动等较短期(十年尺度)的波动。这项研究首次将从软体动物贝壳中提取此类记录的方法结合在一起，也可以用于获取其他海洋区域的古气候记录。将组装的1000年贝壳生长带时间序列将作为海洋地球化学记录的档案，并将提供给其他工作人员进行其他类型的分析。这项拟议的研究是华盛顿卡内基研究所的G.GoodFriend和伍兹霍尔海洋研究所的C.Weidman之间的合作研究项目。

9713547 Weidman This study will produce an ocean temperature record for the northern North Atlantic covering the last 1000 years, based on stable oxygen isotope analysis of annual growth bands of the long-lived bivalve Arctica islandica. Bands from the period ca. 500-1000 yr B.P. will be dated by radiocarbon analysis, whereas those from 100-500 yr B.P. will be dated by aspartic acid racemization which will provide significantly better precision than radiocarbon for this period. An annual 18O record for the last 100 yr has already been constructed from live-collected Arctica (Weidman and Jones, in prep.). The study will be carried out using subfossil shells dredged from surface sediments in the Nantucket Shoals region. This outer continental shelf area is shallow enough to provide a temperature record of upper ocean waters but far enough off shore to be away from the influence of continental freshwater inputs. The site is further distinguished by being the location of a particularly long instrumental record of temperatures obtained from the former Nantucket Lightship and is currently a NOAA long-term weather monitoring site. A time series of ca. 25 shells, spanning the relevant age range and each containing a record of 50 years growth, will be selected for analysis. The second primary goal of this study is to evaluate cross-matching of band width variations among individuals to construct an annual time series, analogous to tree ring series. This has the potential to produce a continuous annual record of environmental changes in the North Atlantic over recent centuries. Long (100 yr), high-resolution records of marine environments are rare, in contrast to terrestrial environments, and are largely absent for higher-latitude ocean regions. This paucity of suitable ocean temperature records restricts our understanding of linkages between atmospheric and oceanic climate variations. Such information is critical to understanding the nature and causes of recent climate changes. These include the long-term (century scale) variations of the Medieval Warm Period, the Little Ice Age, and the warming trend of the 20th century, which have been documented from terrestrial records, as well as shorter-term (decadal scale) fluctuations such as the North Atlantic Oscillation. The methods that are brought together in this study for the first time to extract such records from mollusk shells can also be used to obtain paleoclimatic records from other ocean regions. The 1000-year time series of shell growth bands that will be assembled will serve as an archive of the marine geochemical record and will be made available to other workers for other types of analyses. The proposed study constitutes a collaborative research project between G. Goodfriend at the Carnegie Institution of Washington and C. Weidman at the Woods Hole Oceanographic Institution.