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首页> 外文期刊>Aquatic Sciences >Variation in nitrate uptake and denitrification rates across a salinity gradient in Mediterranean semiarid streams
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Variation in nitrate uptake and denitrification rates across a salinity gradient in Mediterranean semiarid streams

机译：地中海半干旱河流域盐度梯度范围内硝酸盐吸收和反硝化速率的变化

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摘要

Streams are significant locations for nitrate (NO_3~-) processing within landscapes. This is especially important in dry climates given the limited water availability for biological processes elsewhere. In arid and semiarid regions, many streams are naturally saline. Elevated salinity can constrain the structure and function of aquatic organisms, which is expected to increase worldwide being associated to global warming. We investigated whole-reach NO_3~- uptake and denitrification in nine semiarid streams of variable water salinity (i.e. from freshwater to hyposaline) to test if NO_3~- processing would decrease with increasing salinity. We used pulse additions and Tracer Addition for Spiraling Curve Characterization (TASCC) to measure whole-reach uptake of added NO_3~-, and the acetylene block technique to measure sediment denitrification. TASCC results showed that only five of nine streams were able to retain added NO_3~-. Of these five retentive streams, four were saline; however, salinity did not control significantly the variation in whole-reach NO_3~- uptake observed across streams. Other measured environmental variables such as streambed NH_4~+ and organic carbon availability were better at explaining this variation. Denitrification was detected in all streams except one and its variation across streams was also independent of salinity. Although denitrification rates tended to be high, their contribution to whole-reach NO_3~- uptake was insignificant (≤2.16 ％). Alternative pathways, heterotrophic assimilation and/or dissimilatory NO_3~- reduction to NH_4~+, were probably responsible for most whole-reach NO_3~-uptake. Together, our results highlight that the function of streams in controlling external NO_3~- inputs is highly variable and salinity does not apparently constrain this role.
机译：溪流是景观中硝酸盐（NO_3〜-）处理的重要位置。鉴于其他地方生物过程的可用水有限，这在干旱气候中尤其重要。在干旱和半干旱地区，许多溪流都是天然盐。盐度升高会限制水生生物的结构和功能，预计与全球变暖有关，这将在全世界范围内增加。我们研究了九种不同水盐度（即从淡水到次盐水）的半干旱河流中全程NO_3〜-的吸收和反硝化作用，以测试NO_3〜-的处理量是否会随着盐度的增加而减少。我们使用脉冲加法和示踪剂加法进行螺旋曲线表征（TASCC）来测量所添加的NO_3〜-的全范围吸收，并使用乙炔嵌段技术来测量沉积物的反硝化作用。 TASCC结果表明，九种流中只有五种能够保留添加的NO_3〜-。在这五个保持流中，有四个是盐水。然而，盐度并不能显着控制整个溪流中全程NO_3〜-吸收的变化。其他测得的环境变量，例如流化床NH_4〜+和有机碳的利用率，可以更好地解释这种变化。除一条溪流外，其他所有溪流均检测到反硝化作用，并且其在溪流中的变化也与盐度无关。尽管反硝化率趋于高，但它们对全范围NO_3〜-吸收的贡献微不足道（≤2.16％）。替代途径，异养同化和/或异化NO_3〜-还原为NH_4〜+可能是大多数全范围NO_3〜吸收的原因。总之，我们的结果表明，流在控制外部NO_3〜-输入中的功能是高度可变的，盐度显然没有限制此作用。

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  • 来源
    《Aquatic Sciences》 |2014年第2期|295-311|共17页
  • 作者

    Maria Isabel Arce; Daniel von Schiller; Rosa Gomez;

  • 作者单位

    Department of Ecology and Hydrology, Faculty of Biology, Regional Campus of International Excellence 'Campus Mare Nostrum', University of Murcia, Campus of Espinardo, 30100 Murcia, Spain,Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Mueggelseedamm 301, 12587 Berlin, Germany;

    Catalan Institute for Water Research (ICRA), Emili Granit, 101, Edifici H2O, 17003 Girona, Spain;

    Department of Ecology and Hydrology, Faculty of Biology, Regional Campus of International Excellence 'Campus Mare Nostrum', University of Murcia, Campus of Espinardo, 30100 Murcia, Spain;

  • 收录信息 美国《科学引文索引》(SCI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Uptake; Retention; Denitrification; Salinity; TASCC; Mediterranean streams;

    机译：吸收;保留;反硝化;盐度;TASCC;地中海溪流;

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