Department of Chemistry and Biochemistry, University of Mississippi, University, MS, 38677, USA.
College of Chemical Engineering, Zhejiang University of Technology, No.18 Chaowang Road, Hangzhou, 310032, Zhejiang, China.
Environ Sci Pollut Res Int. 2018 May;25(13):13195-13202. doi: 10.1007/s11356-018-1775-y. Epub 2018 Mar 22.
We modified a popular and inexpensive quadcopter to collect gaseous mercury (Hg) on gold-coated quartz cartridges, and analyzed the traps using cold vapor atomic fluorescence spectrometry. Flight times averaged 16 min, limited by battery life, and yielded > 5 pg of Hg, well above the limit of detection (< 0.2 pg). We measured progressively higher concentrations upon both vertical and lateral approaches to a dish containing elemental Hg, demonstrating that the method can detect Hg emissions from a point source. Using the quadcopter, we measured atmospheric Hg near anthropogenic emission sources in the mid-south USA, including a municipal landfill, coal-fired power plant (CFPP), and a petroleum refinery. Average concentrations (± standard deviation) immediately downwind of the landfill were higher at ground level and 30 m compared to 60 and 120 m (5.3 ± 0.5 ng m, 5.4 ± 0.7 ng m, 4.2 ± 0.7 ng m, and 2.5 ± 0.3 ng m, respectively). Concentrations were also higher at an urban/industrial area (Memphis) (3.3 ± 0.9 ng m) compared with a rural/background area (1.5 ± 0.2 ng m). Due to airspace flight restrictions near the CFPP and refinery, we were unable to access near-field (stack) plumes and did not observe differences between upwind and downwind locations. Overall, this study demonstrates that highly maneuverable multicopters can be used to probe Hg concentrations aloft, which may be particularly useful for evaluating Hg emissions from remote landscapes and transient sources that are inadequately characterized and leading to uncertainties in ecosystem budgets.
我们对一款常见且廉价的四轴飞行器进行了改装，使其能够在镀金石英管上采集气态汞（Hg），并用冷原子荧光光谱法对收集的样品进行分析。单次飞行的平均时长为 16 分钟，受限于电池寿命，每次飞行能采集到的 Hg 量超过 5pg，远高于检测限（<0.2pg）。当飞行器对盛有元素 Hg 的器皿进行垂直和水平逼近时，我们检测到 Hg 浓度逐渐升高，这表明该方法可以检测到来自点源的 Hg 排放。我们使用四轴飞行器在美国中南部的人为排放源附近测量大气 Hg，包括一个城市垃圾填埋场、燃煤电厂（CFPP）和一个炼油厂。垃圾填埋场下风处的 Hg 浓度在地面和 30m 高度处高于 60m 和 120m 高度处（分别为 5.3±0.5ngm、5.4±0.7ngm、4.2±0.7ngm 和 2.5±0.3ngm）。在城市/工业区（孟菲斯）的 Hg 浓度也高于农村/背景区（1.5±0.2ngm）。由于 CFPP 和炼油厂附近的空域飞行限制，我们无法进入近场（烟囱）羽流，也没有观察到上风和下风位置之间的差异。总的来说，这项研究表明，高度机动的多旋翼飞行器可用于探测高空的 Hg 浓度，这对于评估偏远景观和瞬态源的 Hg 排放特别有用，因为这些源的特征描述不足，导致生态系统预算存在不确定性。
