Cerrato José M, Blake Johanna M, Hirani Chris, Clark Alexander L, Ali Abdul-Mehdi S, Artyushkova Kateryna, Peterson Eric, Bixby Rebecca J
Department of Civil Engineering, MSC01 1070, University of New Mexico, Albuquerque, New Mexico 87131, USA.
Department of Chemistry, MSC03 2060, University of New Mexico, Albuquerque, New Mexico 87131, USA.
Environ Sci Process Impacts. 2016 Aug 10;18(8):1078-89. doi: 10.1039/c6em00123h.
The reactivity of metals associated with ash from wood collected from the Valles Caldera National Preserve, Jemez Mountains, New Mexico, was assessed through a series of laboratory experiments. Microscopy, spectroscopy, diffraction, and aqueous chemistry measurements were integrated to determine the chemical composition of wood ash and its effect on water chemistry. Climate change has caused dramatic impacts and stresses that have resulted in large-scale increases in wildfire activity in semi-arid areas of the world. Metals and other constituents associated with wildfire ash can be transported by storm event runoff and negatively affect the water quality in streams and rivers. Differences among ash from six tree species based on total concentrations of metals such as Ca, Al, Mg, Fe, and Mn were identified using non-metric multidimensional analysis. Metal-bearing carbonate and oxide phases were quantified by X-ray diffraction analyses and X-ray spectroscopy analyses. These metal-bearing carbonate phases were readily dissolved in the first 30 minutes of reaction with 18 MΩ water and 10 mM HCO3(-) in laboratory batch experiments which resulted in the release of metals and carbonates in the ash, causing water alkalinity to increase. However, metal concentrations decreased over the course of the experiment, suggesting that metals re-adsorb to ash. Our results suggest that the dissolution of metal-bearing carbonate and oxide phases in ash and metal re-adsorption to ash are relevant processes affecting water chemistry after wildfire events. These results have important implications to better understand the impact of wildfire events on water quality.
通过一系列实验室实验，对从新墨西哥州杰梅斯山脉瓦莱斯卡尔德拉国家保护区采集的木材灰烬中所含金属的反应活性进行了评估。综合运用显微镜、光谱学、衍射和水相化学测量方法，以确定木灰的化学成分及其对水化学的影响。气候变化已造成巨大影响和压力，导致世界半干旱地区野火活动大规模增加。与野火灰烬相关的金属和其他成分可通过暴雨径流传输，并对溪流和河流的水质产生负面影响。利用非度量多维分析，确定了六种树种灰烬中钙、铝、镁、铁和锰等金属总浓度的差异。通过X射线衍射分析和X射线光谱分析对含金属的碳酸盐和氧化物相进行了定量。在实验室批次实验中，这些含金属的碳酸盐相在与18 MΩ水和10 mM HCO3(-)反应的前30分钟内很容易溶解，导致灰烬中的金属和碳酸盐释放出来，使水的碱度增加。然而，在实验过程中金属浓度下降，这表明金属重新吸附到了灰烬上。我们的研究结果表明，灰烬中含金属的碳酸盐和氧化物相的溶解以及金属重新吸附到灰烬上是影响野火事件后水化学的相关过程。这些结果对于更好地理解野火事件对水质的影响具有重要意义。
