Acidic episodes retard the biological recovery of upland British streams from chronic acidification
Acidic episodes retard the biological recovery of upland British streams from chronic acidification
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DOI：
10.1111/j.1365-2486.2007.01437.x
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发表时间：
2007-11-01
影响因子：
11.6
通讯作者：
Ormerod, S. J.
中科院分区：
文献类型：
--
作者：
Kowalik, Renata A.;Cooper, D. M.;Ormerod, S. J.
我们检验了两个预测，以支持这一假设，即人为酸化事件可能解释从酸化中恢复的英国高地溪流较差的生物反应：(I)无脊椎动物组合在间歇性河流和缓冲良好的河流之间应该不同；(Ii)这些影响应该区分由人为酸化引起的地点，而不是碱阳离子稀释或海盐沉积。慢性和间歇性酸性的溪流很普遍，而且间歇性反映的是酸滴定而不是稀释。与苏格兰相比，威尔士的非海洋硫酸盐(16-18%对5-9%)和硝酸盐(4-6%对1-2%)对阴离子负荷的贡献更大，威尔士溪流也有更大比例的非海洋来源的水系硫酸盐(-66%对35-46%)。在抽样的事件中，海盐很少是间歇性ANC或pH下降的主要原因。相比之下，与由稀释(pH 5.4+/-0.6；116+/-110mgAl L-1)或保持中性(PH6.7+/-1.0；50+/-45mgAl L-1)相比，在事件期间，由强人为酸驱动的溪流的pH值(5.0+/-0.6)较低(2 88/-2 71 mg L-1)，而溶解铝(2 88/-2 71 mgAl L-1)较高。这两个生物学预测都得到了支持：无脊椎动物的组合在不同插曲化学的地点不同，而几个酸敏感物种只有在插曲反映人为酸化的地方才不存在。我们的结论是，强酸性阴离子--主要是非海洋硫酸盐--仍然在英国对酸敏感的地区造成明显的间歇性酸化，并可能充分解释许多地方生物恢复缓慢的原因。
We tested two predictions required to support the hypothesis that anthropogenic acidic episodes might explain the poor biological response of upland British streams otherwise recovering from acidification: (i) that invertebrate assemblages should differ between episodic and well-buffered streams and (ii) these effects should differentiate between sites with episodes caused by anthropogenic acidification as opposed to base-cation dilution or sea-salt deposition. Chronic and episodically acidic streams were widespread, and episodes reflected acid titration more than dilution. Nonmarine sulphate (16-18% vs. 5-9%), and nitrate (4-6% vs. 1-2%) contributed more to anion loading during episodes in Wales than Scotland, and Welsh streams also had a larger proportion of total stream sulphate from nonmarine sources (64-66% vs. 35-46%). Sea-salts were rarely a major cause of episodic ANC or pH reduction during the events sampled. By contrast, streams with episodes driven by strong anthropogenic acids had lower pH (5.0 +/- 0.6) and more dissolved aluminium (288 +/- 271 mu g L-1) during events than where episodes were caused by dilution (pH 5.4 +/- 0.6; 116 +/- 110 mu g Al L-1) or where streams remained circumneutral (pH 6.7 +/- 1.0; 50 +/- 45 mu g Al L-1). Both biological predictions were supported: invertebrate assemblages differed among sites with different episode chemistry while several acid-sensitive species were absent only where episodes reflected anthropogenic acidification. We conclude that strong acid anions - dominantly nonmarine sulphate - still cause significant episodic acidification in acid-sensitive areas of Britain and may be a sufficient explanation for slow biological recovery in many locations.