• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Paleohydrologic reconstruction of three shallow basins, Slave River Delta, NWT, using stable isotope methods.
【24h】

Paleohydrologic reconstruction of three shallow basins, Slave River Delta, NWT, using stable isotope methods.

机译：使用稳定同位素方法对三个浅盆地（奴隶河三角洲）进行了古水文重建。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The long-term natural hydrological variability of the Slave River Delta (SRD), NWT, is not well documented and needs to be further developed to provide temporal context to understand and evaluate impacts of Slave River (SR) floodwater influence and climate variability and change on contemporary hydro-ecological conditions of the SRD. The SRD has broad ecological and cultural significance, as it provides extensive habitat for wildlife and is important for local First Nations community who have an historical connection with the delta and its resources. Concerns have been raised over recently reported drying trends in the SRD over the past few decades and have largely been attributed to regulation of the Peace River (PR), which supplies the SR with ∼65% of its annual flow.; Modern lake water balances (2003 to 2005) of three lakes from different hydrological settings within the SRD were assessed using oxygen (delta 18O) and hydrogen (delta2H) stable isotope analyses. Contemporary lake water balance was used to constrain paleohydrological interpretations of cellulose-inferred delta18O from lake sediment cores. Past hydro-ecological conditions of each lake was also reconstructed using bulk organic carbon and nitrogen elemental and stable isotope analyses. Lead-210 (210Pb) and caesium-137 (137Cs) analyses were conducted to establish sediment core chronologies.; Results from lake water delta18O and delta 2H analyses of SD20, an evaporation-dominated basin, indicate seasonal precipitation, snowmelt runoff and evaporation predominantly control the water balance of this lake. An ∼215-year cellulose-inferred delta18 Olw, delta13C and delta15N record of SD20 provides paleoclimatological evidence that recently reported dry conditions in the SRD are not outside of the range of natural variability for the delta. SD20 paleohydrological records follow a similar pattern as PAD5, a climate-driven basin in the Peace-Athabasca Delta (PAD), and align with paleoclimate records reconstructed from tree-ring sequences from the Athabasca River headwaters. Results provide long-term documentation of how hydrological conditions have varied in an area of the SRD that is largely beyond the reach of river flooding.; Lake water delta18O and delta2H analyses of SD2, a flood-dominated basin, indicate that SR floodwaters control the water balance of SD2. An ∼100 year carbon and nitrogen elemental and isotope record for SD2 documents event-scale flooding on the SR and indicates that regulation of the PR has not decreased flood frequency at this site over the past ∼40 years. The late 1940s and 1950s likely represent the period of lowest river discharge over the past century. The SD2 C/N record is similar to the C/N record of PAD15, an oxbow lake in the PAD, indicating common upstream drivers control flood frequency in both deltas.; Lake water delta18O and delta2H analyses of SD28, an exchange-dominated basin, suggest that SR flooding and evaporation predominantly control the water balance of SD28. Reconstructed cellulose-inferred delta 18Olw suggest an increase in river flooding may have occurred over the past ∼40 years. However, reconstructing past hydro-ecological conditions is more difficult at this site due to its long channel connection to the SR, which suppresses the geochemical signals recorded in the lake sediment.
机译：奴隶河三角洲（NWT）的长期自然水文变异性没有得到充分的记录，需要进一步发展以提供时间背景，以理解和评估奴隶河（SR）洪水影响以及气候变异性和变化关于SRD的当代水生态条件。 SRD具有广泛的生态和文化意义，因为它为野生生物提供了广阔的栖息地，并且对于与三角洲及其资源有着历史渊源的当地原住民社区至关重要。过去几十年来，人们对最近报道的SRD干旱趋势提出了担忧，这在很大程度上归因于和平河（PR）的监管，该河为SR提供了约65％的年流量。使用氧气（δ18O）和氢（δ2 H）稳定同位素分析评估了SRD内不同水文环境的三个湖泊的现代湖泊水平衡（2003年至2005年）。当代的湖泊水平衡被用来限制湖泊沉积物核心中纤维素推断的δ18O的古水文解释。还使用大量有机碳和氮元素以及稳定的同位素分析来重建每个湖泊过去的水生态条件。进行了铅210（210Pb）和铯137（137Cs）分析以建立沉积物芯年代。对以蒸发为主的盆地SD20的湖泊水delta18O和delta 2H分析的结果表明，季节性降水，融雪径流和蒸发主要控制着该湖的水平衡。约有215年的由纤维素推断的SD20的delta18 Olw，delta13C和delta15N记录提供了古气候学证据，即最近报道的SRD中的干燥条件不在该三角洲的自然变异范围之内。 SD20的古水文记录与和平-阿萨巴斯卡三角洲（PAD）的气候驱动盆地PAD5遵循相似的模式，并且与从阿萨巴斯卡河上游源头的年轮序列重建的古气候记录保持一致。结果提供了长期记录，说明SRD地区的水文条件如何变化，而该地区在很大程度上是河流洪水无法达到的。 SD2（一个以洪水为主的盆地）的湖水delta18O和delta2H分析表明，SR洪水控制着SD2的水平衡。 SD2的约100年碳，氮元素和同位素记录记录了SR上的事件规模洪水，并表明PR的监管在过去约40年中并未降低该地点的洪水频率。 1940年代末和1950年代末可能是过去一个世纪以来河流流量最低的时期。 SD2的C / N记录与PAD15中的牛弓湖PAD15的C / N记录相似，这表明常见的上游驱动器控制两个三角洲的洪水频率。对以交换为主的盆地SD28的湖水delta18O和delta2H分析表明，SR驱和蒸发主要控制着SD28的水平衡。重建的纤维素推断三角洲18Olw表明，在过去约40年中，河道洪水泛滥的情况有所增加。但是，由于该区域与SR的长通道连接，因此在该地点重建过去的水生态条件更加困难，这抑制了记录在湖泊沉积物中的地球化学信号。

著录项

  • 作者

    Mongeon, Cherie.;

  • 作者单位

    Wilfrid Laurier University (Canada).;

  • 授予单位 Wilfrid Laurier University (Canada).;
  • 学科 Physical Geography.
  • 学位 M.E.S.
  • 年度 2008
  • 页码 130 p.
  • 总页数 130
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 自然地理学;
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号