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首页> 外文学位 >Sources and controls of sulphur export in Precambrian Shield catchments in south-central Ontario.
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Sources and controls of sulphur export in Precambrian Shield catchments in south-central Ontario.

机译：安大略省中南部的前寒武纪盾构流域的硫出口来源和控制。

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摘要

A series of studies was undertaken at Plastic Lake-1 (PC1) to determine the sources and controls on S cycling in small headwater catchments on the Precambrian Shield in south-central Ontario. Two observations were made about the S cycle in this region: (1) all streams exhibit highly coherent temporal patterns in SO4 concentrations and export, and (2) most catchments exported more SO4 in stream water than is received in bulk deposition during the past 2 decades. Synchronous temporal patterns in annual SO 4 concentrations in both upland and wetland-draining streams were related to changes in climate, specifically those factors that determine catchment dryness. The number of days with no stream flow or stream flow below a critical threshold was a good predictor of the average stream SO4 concentration in a particular year. Sulphate chemistry in the PC1 outflow is highly dependent on processes occurring in a conifer Sphagnum swamp located immediately upstream of the chemical sampling station. Hydrologic inputs to the swamp during the summer determine whether S is retained or released from peat on an annual basis. Drying and re-wetting of Sphagnum-derived peat caused a substantial increase in soluble SO4 in laboratory experiments, which was slightly enhanced at higher temperature, but alternating moisture conditions had no immediate effect on Sphagnum. Despite large inter-annual changes in SO4 release, over the long-term (i.e. 20-years) SO4 inputs and exports from the swamp are in approximate balance. In contrast, the upland portion of PC1 ( i.e. PC1–08) consistently exports more SO4 than is input in bulk deposition in every year of record. Even when inputs are increased to account for potential underestimates in dry deposition or weathering, the majority of catchments in this region exhibit net export in many years. Two internal sources are suggested to account for negative budgets: desorption and mineralization. Adsorption/desorption reactions respond directly to changes in SO4 input concentration, and lysimeter data indicate the importance of these processes for buffering short-term changes in SO4 concentration in LFH percolate. Desorption may be the primary direct response of upland soil to decreasing SO4 inputs in deposition and may substantially extend the period of net SO4 export in catchments that have large adsorbed SO4 pools such as PC1. However, the adsorbed pool may be sustained by continuous net release from mineralization, and should also be considered in budget calculations. Mineralization was shown to be responsive to drying and re-wetting events and temperature, although results varied among different materials. Sulphate release from mineral soil did not appear to be influenced by changing moisture, temperature or deposition chemistry in laboratory experiments, although adsorption/desorption reactions may have largely masked small changes in SO4 release via mineralization. The magnitude of organic S storage in mineral soil indicates that this pool could be an important source of export over the long-term. (Abstract shortened by UMI.)
机译：在Plastic Lake-1（PC1）进行了一系列研究，以确定安大略省中南部的前寒武纪盾构中小源头集水区S循环的来源和控制措施。关于该区域的S周期，有两个观察结果：（1）所有流在SO 4 浓度和出口方面表现出高度连贯的时间模式，（2）大多数流域出口更多的SO 4 <在过去的20年中，河水中的水比大体积沉积中的水要多。旱地和湿地排水流中SO 4 年浓度的同步时间模式与气候变化有关，特别是那些决定流域干燥的因素。没有水流或水流低于临界阈值的天数可以很好地预测特定年份的平均水流SO 4 浓度。 PC1流出物中的硫酸盐化学高度依赖于位于化学采样站上游的针叶树沼泽中发生的过程。在夏季，沼泽的水文输入量决定了每年是保留还是从泥炭中释放出硫。在实验室实验中，泥炭来源的泥炭的干燥和再润湿导致可溶性SO 4 大量增加，在较高温度下略有增加，但在交替的水分条件下没有对泥炭藓的即时效果。尽管SO 4 释放的年度变化很大，但长期（即。20年）SO 4 的投入和出口沼泽处于大致平衡状态。相反，在有记录的每一年中，PC1的高地部分（，即 .PC1–08）始终出口的SO 4 比散装沉积中输入的更多。即使增加投入以解决干旱沉积或风化的潜在低估，该地区大多数集水区多年仍显示出净出口。建议使用两个内部来源来解释负预算：解吸和矿化。吸附/解吸反应直接响应SO 4 输入浓度的变化，溶渗仪数据表明这些过程对于缓冲LFH渗滤液中SO 4 浓度的短期变化的重要性。解吸可能是陆地土壤对沉积物中SO 4 输入减少的主要直接反应，并可能大大延长SO 4 净吸收量 sub> 4 池，例如PC1。但是，被吸收的矿藏可能通过矿化过程中连续不断的净释放而得以维持，并且在预算计算中也应予以考虑。尽管结果在不同的材料中有所不同，但矿化显示出对干燥和再润湿事件以及温度有响应。尽管吸附/解吸反应可能很大程度上掩盖了SO 4 via via 的微小变化，但吸附/解吸反应可能掩盖了矿物质土壤中硫酸盐的释放不受水分，温度或沉积化学变化的影响。 / italic>矿化。矿质土壤中有机S的储存量表明，该库可能是长期的重要出口来源。 （摘要由UMI缩短。）

著录项

  • 作者

    Eimers, M. Catherine.;

  • 作者单位

    University of Waterloo (Canada).;

  • 授予单位 University of Waterloo (Canada).;
  • 学科 Biogeochemistry.; Geochemistry.; Biology Ecology.
  • 学位 Ph.D.
  • 年度 2002
  • 页码 p.4825
  • 总页数 271
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 生物地球化学、气体地球化学;
  • 关键词

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