Data for: Pollution monitoring in two urban areas of Cuba by using Tillandsia recurvata (L.) L. and top soil samples: spatial distribution and sources

Samples of T. recurvata were collected in 5 and 4 sites of Santa Clara and Cienfuegos, respectively. Four sampling campaigns were carried out between 2015 and 2016: in Santa Clara, samples were collected in November 2015 and March, June and September 2016; while in Cienfuegos sampling campaigns took place in June and December 2015, and June and September 2016. The monitoring sites at both cities were located in roads or highways with high level of vehicular traffic (sites 1 and 3 in Cienfuegos and 2, 3 and 4 in Santa Clara) and in parks surrounded by busy roads (sites 2 and 4 in Cienfuegos and 1 and 5 in Santa Clara). At each sampling site, composite samples, made up of 3 to 6 plants from the same tree or nearby trees, were taken at a height of 2 m or higher in order to minimize resuspension of soils and particles from roads. Top soils samples (0-5 cm of roadside or parks soils) were collected in the same sampling places at the same time. Additionally, three composite samples of T. recurvata were collected in the Botanic Garden of Cienfuegos (site 5 in Figure 1) in September 2016 and considered as the control site (no soil samples were taken at this site). All samples were stored and labeled in self-sealed polyethylene bags and immediately taken to the laboratory for preparation.
Unwashed samples of T. recurvata and top soils were oven-dried at 45˚C to constant weight, grounded and passed through a 250 µm sieve. The fraction <250 µm was stored in polyethylene bags until further analysis.
Concentrations of 46 major and trace elements were determined using inductively coupled plasma mass spectrometry (ICP-MS, Agilent 7500a). About 0.25 g (dry weight) of epiphytic plant and top soils samples were digested in a closed microwave digestion system (CEM Co., Mars X press) using 9 mL of concentrated nitric acid and 12 ml aqua regia, respectively. A multi-element solution (Li, Sc, Y, In, Bi) was added to each sample and used as internal standards for further analysis by ICP-MS. Mercury concentrations were determined by atomic absorption spectrometry using a Mercury Analyzer (MA-2000 Series, Nippon) on 50 mg of sample. Soil samples from the 4th sampling campaign were not measured by ICP-MS due to technical issues.
For the quality control of the analytical procedure, a pine needle sample from the 15th ICP Forests ring test and the interlaboratory reference material M2-Pleurozium Schreberi were used for T. recurvata. For top soils, the certified reference materials Soil 0217-CM-73007 and 0217-CM-7003 (Silty Clay Loam) were used. In both cases, these QC samples, one blank (only reagents) and one duplicated sample were measured every ten samples. Elemental recovery from reference materials were in the range 76-101% with a relative standard deviation (RSD) <7% for epiphytic plants and 74-115% with RSD<9% for top soils. Here, the heavier lanthanoids (Dy to Lu) showed lower recoveries in the range 47-63% (RSD<6%). The RSD from duplicated samples were <10%.

在2015年至2016年间，于圣克拉拉和辛费古埃斯的5个和4个地点采集了T. recurvata样本。开展了四次采样活动：在圣克拉拉，样本采集于2015年11月以及2016年3月、6月和9月；而在辛费古埃斯，采样活动分别在2015年6月和12月以及2016年6月和9月进行。两座城市的监测地点均位于车流量大的道路或高速公路旁（辛费古埃斯为1号和3号地点，圣克拉拉为2号、3号和4号地点）以及繁忙道路环绕的公园内（辛费古埃斯为2号和4号地点，圣克拉拉为1号和5号地点）。在每个采样地点，选取由3至6株同树或邻近树木组成的复合样本，在2米或更高的高度处采集，以最大限度地减少土壤和道路颗粒的再悬浮。同时，在同一采样地点和时间收集了0-5厘米厚的表层土壤样本。此外，在2016年9月于辛费古埃斯的植物园（图1中的5号地点）采集了三个T. recurvata复合样本，并将其视为对照地点（该地点未采集土壤样本）。所有样本均存放在自封的聚乙烯袋中，并立即送往实验室进行预处理。
未经清洗的T. recurvata样本和表层土壤在45°C的烤箱中烘干至恒重，研磨并通过250微米的筛子。小于250微米的部分存储在聚乙烯袋中，以待进一步分析。
使用电感耦合等离子体质谱法（ICP-MS，Agilent 7500a）测定了46种主要和微量元素的浓度。约0.25克（干重）的附生植物和表层土壤样本分别在使用9毫升浓硝酸和12毫升王水的封闭式微波消解系统中消解。每个样本中添加了一种多元素溶液（Li、Sc、Y、In、Bi），用作ICP-MS进一步分析的内部标准。汞浓度通过原子吸收光谱法使用汞分析仪（MA-2000系列，Nippon）在50毫克样本上测定。由于技术问题，第四次采样活动的土壤样本未使用ICP-MS进行测量。
为了分析程序的质量控制，使用了来自第15次ICP森林环测试的松针样本和实验室间参考物质M2-Pleurozium Schreberi来对T. recurvata进行测试。对于表层土壤，使用了认证参考物质土壤0217-CM-73007和0217-CM-7003（粉砂粘土壤）。在这两种情况下，每十个样本测量一次这些质量控制样本，包括一个空白样本（仅试剂）和一个重复样本。参考材料中的元素回收率在76-101%之间，对于附生植物，相对标准偏差（RSD）小于7%；对于表层土壤，元素回收率在74-115%之间，RSD小于9%。在此，较重的镧系元素（Dy至Lu）的回收率在47-63%之间（RSD小于6%）。重复样本的RSD小于10%。