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The response of diatom assemblages in a Jamaican coastal lagoon to hurricane and drought activity over the past millennium
The Holocene ( IF 2.4 ) Pub Date : 2021-05-29 , DOI: 10.1177/09596836211019095
Charlotte A Heller 1 , Neal Michelutti 1 , Michael J Burn 2 , Suzanne E Palmer 3 , John P Smol 1
Affiliation  

Reconstructing pre-industrial hurricane activity and aridity from natural archives places modern trends within the context of long-term natural variability. The first reconstruction of Atlantic hurricane activity in Jamaica was based on a sediment record previously obtained from a coastal lagoon. Specifically, an Extended Hurricane Activity (EHA) index was developed from high-resolution geochemical data that linked fluctuations in lake-level changes to rainfall variability associated with hurricane activity. Here, we analyse the same sediment core from which the EHA index was developed to assess the response of biological indicators, namely fossil diatom assemblages and sediment chlorophyll a (chl-a) concentrations, to hydrometeorological events (tropical cyclone-induced precipitation and droughts) over the past ~1500 years. The diatom assemblages responded sensitively to changes in salinity associated with lake-level changes driven by the balance of precipitation and evaporation. Aquatic production (inferred from sediment chl-a, which includes its main diagenetic products) and salinity (inferred from ITRAXTM µXRF chlorine counts) vary inversely following ca. 1300 CE, likely due to enhanced nutrient delivery from freshwater runoff during periods of elevated precipitation. Although the temporal resolution of our biological data is less-well resolved than that of the geochemical record, it generally tracks long-term trends in rainfall variability inferred by the EHA index over the past millennium. This further demonstrates the potential of using biological proxies from coastal lagoons to track past hurricane activity and aridity.



中文翻译:

过去千年牙买加沿海泻湖中硅藻群对飓风和干旱活动的响应

从自然档案中重建工业化前的飓风活动和干旱,将现代趋势置于长期自然变化的背景下。牙买加大西洋飓风活动的首次重建基于先前从沿海泻湖获得的沉积物记录。具体而言,扩展飓风活动 (EHA) 指数是根据高分辨率地球化学数据开发的,该数据将湖泊水位变化的波动与与飓风活动相关的降雨变化联系起来。在这里,我们分析了开发 EHA 指数的同一沉积物核心,以评估生物指标的响应,即化石硅藻组合和沉积物叶绿素a(chl- a) 浓度,到过去约 1500 年的水文气象事件(热带气旋引起的降水和干旱)。硅藻群对与由降水和蒸发平衡驱动的湖泊水位变化相关的盐度变化反应灵敏。水产产量(从沉积物 chl- a推断,包括其主要成岩产物)和盐度(从 ITRAX TM推断µXRF 氯计数)在大约之后成反比变化。公元 1300 年,可能是由于降水量增加期间淡水径流的养分输送增强。尽管我们的生物数据的时间分辨率不如地球化学记录的分辨率好,但它通常跟踪过去千年 EHA 指数推断的降雨变化的长期趋势。这进一步证明了使用来自沿海泻湖的生物代理来追踪过去的飓风活动和干旱的潜力。

更新日期:2021-05-30
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