泰山2021年夏季云水可溶性离子及痕量金属元素的浓度特征

Characteristics of Water-Soluble Inorganic Ions and Trace Metal Elements in Cloud Water of Mt.Tai in Summer 2021

2021年7月16日—8月4日期间在泰山山顶(海拔1 530 m)采集了21个云水样品,使用离子色谱仪(IC)和电感耦合等离子体质谱仪(ICP-MS)测定了云水中9种水溶性离子和20种痕量元素的浓度。结果表明,泰山山顶云水的pH值在5.50~6.95之间,平均值为6.63,电导率在29.2~281.0μS·cm^(-1),平均值为73.0μS·cm^(-1);水溶性离子的平均浓度为1 109μmol·L^(-1),其中NH_(4)^(+)浓度最高(457μmol·L^(-1)),其次是NO_(3)^(-)(179μmol·L^(-1))、Cl^(-)(170μmol·L^(-1))和SO_(4)^(2-)(138μmol·L^(-1))。云水中痕量元素的平均质量浓度为407μg·L^(-1),质量浓度较高的痕量元素有Mg、Zn、Fe、Al、V,质量浓度分别为116、76、43、36和34μg·L^(-1)。与泰山云水的以往观测结果相比,云水的pH值显著增加,酸性云的比例显著降低,表明酸云的情况显著改善;电导率明显下降,SO_(4)^(2-)浓度占比有所下降,表明二次污染显著降低,但是,NH_(4)^(+)浓度贡献突出,可能大气中NH3排放问题仍然突出。

21 cloud water samples were collected at the summit of Mt.Tai(1 530 m) from 16/07/2021 to 04/08/2021. 9 water-soluble inorganic ions and 20 trace metal elements in the samples were determined by ion chromatography(IC) and inductively coupled plasma-mass spectrometry(ICP-MS). The results showed that the pH value of the cloud water ranges from 5.50 to 6.95, with an average value of 6.63, and the electrical conductivity is distributed between 29.2 and 281 μS·cm^(-1), with an average value of 73 μS·cm^(-1). The average concentration of water-soluble inorganic ions is 1109 μmol·L^(-1), of which NH_(4)^(+) has the highest concentration(457 μmol·L^(-1)), followed by NO_(3)^(-)(179 μmol·L^(-1)), Cl-(170 μmol·L^(-1)) and SO_(4)^(2-)(138 μmol·L^(-1)). The average mass concentration of trace elements in the cloud is 407 μg·L^(-1), and Mg, Zn, Fe, Al, and V have the higher mass concentrations, with the mass concentrations of 116, 76, 43, 36, and 34 μg·L^(-1), respectively. Compared with the previous observations of cloud water in Mt.Tai, the pH value of cloud water increases significantly and the proportion of acid clouds decreases significantly, indicating that the situation of acid clouds has been markedly improved. In addition, the conductivity of cloud water obviously decreases and the contribution of SO_(4)^(2-) decreases, suggesting that the secondary pollution is significantly reduced. However, the contribution of NH_(4)^(+) concentration is outstanding, which indicates that the problem of NH3emission may still be prominent in the atmosphere.