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

这项研究将根据对长寿的北极双壳类岛屿的年生长带的稳定氧同位素分析，得出北大西洋北部过去1000年的海洋温度记录。大约500-1000年B.P.的条带将通过放射性碳分析来定年，而100-500年B.P.的条带将通过天冬氨酸消旋作用来定年，这将比放射性碳提供更好的精度。过去100年的年度180度记录已经从北极的活体采集中构建出来（魏德曼和琼斯，准备中）。这项研究将使用从楠塔基特浅滩地区表层沉积物中挖掘出来的亚化石贝壳进行。这个外大陆架区域足够浅，可以提供上层海水的温度记录，但距离海岸足够远，可以远离大陆淡水输入的影响。该地点的另一个特点是，它拥有从前楠塔基特光船获得的特别长的温度仪器记录，目前是美国国家海洋和大气管理局的长期天气监测点。将选择大约25个壳的时间序列进行分析，这些壳跨越了相关的年龄范围，每个壳都包含了50年的生长记录。本研究的第二个主要目标是评估个体之间的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，长期（100年）的高分辨率海洋环境记录很少，而且在高纬度海洋地区基本上没有。合适的海洋温度记录的缺乏限制了我们对大气和海洋气候变化之间联系的理解。这些信息对于理解近期气候变化的性质和原因至关重要。这些变化包括长期的（世纪尺度）变化，如中世纪暖期、小冰河期和20世纪的变暖趋势，这些变化已从陆地记录中记录下来，以及短期的（年代际尺度）波动，如北大西洋涛动。本研究首次将从软体动物壳中提取此类记录的方法结合在一起，也可用于从其他海洋区域获得古气候记录。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。这项提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的合作研究项目。

9709895 Goodfriend 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. The se 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.