• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Geochemistry of streams, soils, and permafrost and the geochemical effects of climate change in a continuous permafrost region, Arctic Alaska, United States.
【24h】

Geochemistry of streams, soils, and permafrost and the geochemical effects of climate change in a continuous permafrost region, Arctic Alaska, United States.

机译：美国北极阿拉斯加连续多年冻土地区的河流，土壤和多年冻土的地球化学以及气候变化的地球化学影响。

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

Climate warming can impact arctic ecosystems by altering watershed geochemistry through permafrost degradation and increased mineral weathering. This dissertation evaluated the importance of these changes in arctic Alaska by examining permafrost and soil geochemistry, mineral weathering, and changes in stream geochemistry.; Elemental and 87Sr/86Sr geochemistry of streams and soils, permafrost, and soil parent materials from glacial deposit surfaces of varying ages were evaluated. Carbonate content increases with soil depth across all surfaces, and exchangeable P, K, and Ca concentrations are significantly (p0.05) greater in permafrost than in active-layer mineral soil. These results suggest that increasing thaw depth will increase carbonate alkalinity, Ca, K, and P supply to soils and streams across the region. Elemental depletion factors for a subset of these soils forming a chronosequence indicate that carbonate weathering is the dominant weathering process, and long-term weathering rates are 0.5-11 meq m-2 yr-2.; Based on increasing Ca/Na and Ca/Ba and decreasing 87Sr/ 86Sr with depth in soils and permafrost, elemental ratios and 87Sr/86Sr in an arctic stream were used as tracers of the maximum depth of soil water flow and therefore changes in integrated thaw depth across the watershed. From 1994 to 2004, mean 87Sr/ 86Sr values in low-discharge late summer stream water decreased from 0.7122 to 0.7119 (R2=0.62, p=0.012), and Ca/Na and Ca/Ba showed significant increasing trends that were consistent with increasing depth of soil water flowpaths. These trends provide new evidence for increasing thaw depth, despite the lack of measured increases using traditional thaw probe techniques.; The effects of an in-stream thermokarst feature on stream chemistry were also investigated. Solute concentrations, alkalinity, and conductivity were elevated downstream from the thermokarst. Estimates suggest geochemical changes may be detectable downstream in rivers up to 100 times the size of the original affected stream. These data further support the use of stream geochemistry as an indicator of spatially heterogeneous permafrost degradation.; This research suggests that permafrost degradation on the Alaskan North Slope is exposing previously frozen carbonate minerals to weathering, thereby influencing stream geochemistry. These geochemical changes are an important consideration when examining the overall impact of climate change on arctic ecosystems.
机译：气候变暖可通过永久冻土退化和增加的矿物风化作用改变流域的地球化学，从而影响北极生态系统。本文通过研究多年冻土和土壤地球化学，矿物风化以及河流地球化学变化来评估北极阿拉斯加这些变化的重要性。评价了来自不同年龄的冰川沉积物表面的溪流和土壤，多年冻土和土壤母质的元素和87Sr / 86Sr地球化学。碳酸盐含量随土壤深度在所有表面上的增加而增加，永久冻土中可交换的P，K和Ca浓度显着高于活性层矿质土壤（p <0.05）。这些结果表明，增加融化深度将增加碳酸盐碱度，Ca，K和P向整个地区土壤和溪流的供应。这些土壤中形成时间序列的元素的元素耗竭因子表明，碳酸盐风化是主要的风化过程，长期风化率为0.5-11 meq m-2 yr-2。基于增加的Ca / Na和Ca / Ba和减少的87Sr / 86Sr随着土壤和多年冻土层深度的增加，将北极流中的元素比和87Sr / 86Sr用作土壤水流最大深度的示踪剂，因此综合解冻量的变化分水岭的深度。从1994年到2004年，夏末低流量溪流水中的平均87Sr / 86Sr值从0.7122下降到0.7119（R2 = 0.62，p = 0.012），并且Ca / Na和Ca / Ba呈显着增加趋势，与增加趋势一致。土壤水流径的深度。这些趋势为增加解冻深度提供了新的证据，尽管缺乏使用传统解冻探针技术测得的增加量。还研究了河床内热岩溶特征对河床化学的影响。热溶岩下游的溶质浓度，碱度和电导率升高。估计表明，在河流下游的地球化学变化可能是原始受影响河流的100倍之多。这些数据进一步支持了利用溪流地球化学作为空间非均质多年冻土退化的指标。这项研究表明，阿拉斯加北坡的多年冻土退化使先前冻结的碳酸盐矿物暴露于风化作用，从而影响了河流的地球化学。在研究气候变化对北极生态系统的总体影响时，这些地球化学变化是重要的考虑因素。

著录项

  • 作者

    Keller, Kate A.;

  • 作者单位

    University of Michigan.;

  • 授予单位 University of Michigan.;
  • 学科 Geology.; Environmental Sciences.; Geochemistry.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 180 p.
  • 总页数 180
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地质学;环境科学基础理论;地质学;
  • 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