Environmental hazards of fluoride in volcanic ash from the ongoing Eyjafjallajökull eruption, Iceland

冰岛埃亚菲亚德拉冰盖持续喷发造成的火山灰中氟化物的环境危害

• 批准号: NE/I007636/1
• 负责人: Pierre Delmelle
• 金额: $ 3.66万
• 依托单位: University of York
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FI007636%2F1
• 关键词: Environmental; hazards; fluoride; volcanic; ash

Volcanic eruptions can transfer large quantities of sulphur, chlorine and fluorine degassed from magmas to the atmosphere and to terrestrial and aquatic environments, with the potential to result in significant perturbations at various temporal and spatial scales. Fluorine-rich eruptions create particular concerns because the fluorine, which is emitted as fluoride, is highly reactive in the environment, and in elevated concentrations, is toxic for plants, animals, and humans. A dramatic illustration of volcano-induced fluoride pollution is the 1783 eruption of Laki in Iceland, which resulted in substantial economic damage and demographic change in the country. A particularly efficient way of returning volcanic fluoride emissions to the ground is via ash fallout. It is well established that some eruptions produced ash with very high concentrations of fluoride readily soluble in water. This results from reactions between gas and ash in the eruptive plume. In general, the environmental hazards of volcanic fluoride on ash is assessed by surveying the thickness of the ash deposits and by measuring the concentration of water-soluble fluoride associated with the ash. However, recent evidence indicates that fluoride is also present in ash in the forms of poorly water-soluble compounds. This suggests that fluoride is likely to be released under a range of environmental conditions and therefore, must be considered in order to assess the entry and potential environmental hazards posed by fluoride-rich volcanic eruptions. The factors governing the amount of fluoride on ash and the distribution of this fluoride in pools with variable solubility are poorly constrained and await further investigations. In addition, increased knowledge on the behaviour of volcanic fluoride in the environmental compartments (soil, water) affected by ash deposition is also required. The results of such studies will enhance our capacity to assess and predict the environmental and health hazards posed by fluoride-rich eruptions, thereby contributing to risk assessment and management practices, during and in the aftermath of a volcanic crisis. The ongoing activity of Eyjafjallajökull volcano which started on April 13th is producing a sustained plume of gases and fine-grained ash. At the time of writing (21 April), ash has accumulated in deposits >10 cm in residential and farming areas ~20 km south from the crater. The most recent preliminary analyses indicate that the volcano is now producing ash with water-soluble fluoride concentrations up to 800 mg/kg, placing the Eyjafjallajökull ash amongst the most fluoride-rich ash material ever documented. With the eruption showing no clear signs of easing off, there is an urgent need to assess the potential environmental hazards posed by the Eyjafjallajökull ash, and to collect the essential data needed to gain insights into the issues outlined above. A rapid field response is essential to sample and characterise ash before significant environmental leaching and remobilisation. We propose to travel to Iceland immediately to conduct a careful geochemical survey of ash, soil, vegetation and surface water in the affected areas. A preliminary assessment of fluoride contamination will be obtained in the field. Further laboratory analyses of the samples will provide new insights into the modes of occurrence of fluoride on ash and on its release and dispersion upon exposure to environmental agents. The unique data generated from the project will provide new insights into the potential environmental hazards of volcanic fluoride in ash, and will significantly improve our capability to inform risk managers dealing with volcanic crises, including the ongoing Eyjafjallajökull eruption.

火山爆发可将岩浆脱气后的大量硫、氯和氟转移到大气层以及陆地和水生环境中，有可能在不同的时间和空间尺度上造成重大扰动。富氟火山喷发引起了特别的关注，因为以氟化物形式排放的氟在环境中具有高度反应性，并且浓度升高，对植物，动物和人类有毒。1783年冰岛的拉基火山爆发是火山引起的氟化物污染的一个引人注目的例子，它导致了该国的重大经济损失和人口变化。将火山氟化物排放物返回地面的一种特别有效的方法是通过火山灰沉降物。已经确定的是，有些火山爆发产生的火山灰含有很高浓度的易溶于水的氟化物。这是由喷发羽流中气体和火山灰之间的反应造成的。一般来说，火山灰中的氟化物对环境的危害是通过测量火山灰沉积物的厚度和测量与火山灰有关的水溶性氟化物的浓度来评估的。然而，最近的证据表明，氟化物也以水溶性差的化合物的形式存在于灰中。这表明，氟化物可能会在一系列环境条件下释放，因此，必须加以考虑，以评估富含氟化物的火山爆发造成的进入和潜在环境危害。灰上氟化物的量和这种氟化物在具有可变溶解度的池中的分布的控制因素受到很大的限制，有待进一步调查。此外，还需要更多地了解火山氟化物在受火山灰沉积影响的环境分区（土壤、水）中的行为。这些研究的结果将提高我们评估和预测富氟火山喷发对环境和健康造成的危害的能力，从而有助于火山危机期间和之后的风险评估和管理做法。埃亚菲亚德拉冰盖火山从4月13日开始持续活动，产生了持续的气体和细粒火山灰。在撰写本报告时（4月21日），火山灰已经在火山口以南约20公里的居民区和农业区积累了超过10厘米的沉积物。最新的初步分析表明，该火山现在正在产生水溶性氟化物浓度高达800毫克/公斤的火山灰，使埃亚菲亚德拉火山灰成为有史以来最富氟化物的火山灰材料之一。由于火山爆发没有明显的缓和迹象，迫切需要评估埃亚菲亚德拉火山灰造成的潜在环境危害，并收集必要的数据，以深入了解上述问题。在重大的环境沥滤和再活化之前，快速的现场响应对于取样和取样至关重要。我们建议立即前往冰岛，对受影响地区的火山灰、土壤、植被和地表水进行仔细的地球化学调查。将在实地对氟化物污染进行初步评估。对样品进行进一步的实验室分析将提供新的见解，了解灰中氟化物的出现方式及其在暴露于环境因子时的释放和分散情况。该项目产生的独特数据将为火山灰中火山氟化物的潜在环境危害提供新的见解，并将显著提高我们为风险管理人员提供火山危机信息的能力，包括正在进行的埃亚菲亚德拉火山爆发。