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Fractal stream chemistry and its implications for contaminant transport in catchments

机译:分形流化学及其对流域污染物迁移的影响

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摘要

The time it takes for rainfall to travel through a catchment and reach the stream is a fundamental hydraulic parameter that controls the retention of soluble contaminants and thus the downstream consequences of pollution episodes. Catchments with short flushing times will deliver brief, intense contaminant pulses to downstream waters, whereas catchments with longer flushing times will deliver less intense but more sustained contaminant fluxes. Here we analyse detailed time series of chloride, a natural tracer, im both rainfall and runoff from headwater catchments at Plynlimon, Wales. We show that, although the chloride concentrations in rainfall have a white noise spectrum, the chloride concentrations in streamflow exhibit fractal 1/f scaling over three orders of magnitude. The fractal fluctuations in tracer concentrations indicate that these catchments do not have characteristic flushing tunes. Instead, their travel times follow an approximate power-law distribution implying that they will retain a long chemical memory of past inputs. Contaminants will initially be flushed rapidly, but then low-level contamination will be delivered to streams for a surprisingly long time.
机译:降雨穿过集水区并到达河流所花费的时间是基本的水力参数,它控制着可溶性污染物的保留,从而控制了污染事件的下游后果。冲洗时间短的集水区将向下游水域输送短暂的,强烈的污染物脉冲,而冲洗时间较长的集水区将释放较弱但持续时间更长的污染物通量。在这里,我们分析了天然示踪剂氯化物的详细时间序列,包括威尔士普林利蒙源头集水区的降雨和径流。我们表明,尽管降雨中的氯离子浓度具有白噪声谱,但流量中的氯离子浓度在三个数量级上表现出分形1 / f缩放。示踪剂浓度的分形波动表明,这些流域没有特征性的冲洗声调。取而代之的是,它们的行程时间遵循近似的幂律分布,这意味着它们将对过去的输入保留较长的化学记忆。污染物最初将被快速冲洗,但是随后低水平的污染物将在令人惊讶的长时间内被输送到河流中。

著录项

  • 来源
    《Nature》 |2000年第6769期|p.524-527|共4页
  • 作者单位
  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 自然科学总论;
  • 关键词

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