Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Total Environ. 2019 Apr 20;662:218-226. doi: 10.1016/j.scitotenv.2019.01.096. Epub 2019 Jan 11.
Rainwater samples from Shenzhen in south China were collected over the period of a year, and the chemical compositions were measured with the main purpose of understanding the acidification of rainwater and the controlling factors. The pH value of precipitation ranged from 3.72 to 6.77, with a volume-weighted mean (VWM) value of 4.29, and the acid rain frequency was 97%. The VWM concentrations of anions and cations followed the order of SO > Cl > NO and Na > Ca > NH > Mg > K, respectively. Air mass back-trajectory and positive matrix factorization analyses indicated that sources of ions in rainwater were mainly from sea salt, soil dust and anthropogenic activities. Compared with other areas in China, the rainwater of Shenzhen has the lowest values of the NP/AP, ∆pH and NF values of Ca and NH, indicating that the lack of the capacity for neutralization could be the main reason for the severe acid rain problem. It is noteworthy that the rain acidification tendency is obvious, and the pH value has reduced by 1.0 units since the 1980s. Based on a comparison of the chemical compositions of the rainwater from different historical periods, the NO concentration was found to have increased consistently, whereas the NH concentration maintained a decreasing trend since 1980. On the other hand, the nss-SO and nss-Ca concentrations increased after 1980 and then decreased after 1994. Meanwhile, the decreasing pH was accompanied by a decreasing NP/AP ratio. These results suggest that the changes in human activities at different stages of urban development can lead to a synergistic change in the chemical characteristics of precipitation. Both an increase in the acidic species emissions (especially NO) due to rapid economic development and a decrease in the alkaline ions concentration due to urbanization have resulted in the rain acidification tendency in Shenzhen.
采集了中国南方深圳市的雨水样本，时间跨度为一年，主要目的是了解雨水酸化情况及其控制因素。降水的 pH 值范围为 3.72 至 6.77，体积加权平均值（VWM）为 4.29，酸雨频率为 97%。阴阳离子的 VWM 浓度顺序为 SO>Cl>NO 和 Na>Ca>NH>Mg>K。气团后向轨迹和正定矩阵因子分析表明，雨水离子的来源主要是海盐、土壤尘和人为活动。与中国其他地区相比，深圳雨水的 NP/AP、ΔpH 和 Ca 和 NH 的 NF 值最低，表明中和能力不足可能是酸雨严重的主要原因。值得注意的是，雨水酸化趋势明显，自 20 世纪 80 年代以来，pH 值已降低 1.0 个单位。通过比较不同历史时期雨水的化学成分，发现 NO 浓度一直呈上升趋势，而 NH 浓度自 1980 年以来一直呈下降趋势。另一方面，nss-SO 和 nss-Ca 浓度在 1980 年后增加，然后在 1994 年后减少。同时，pH 值的下降伴随着 NP/AP 比值的下降。这些结果表明，城市发展不同阶段人类活动的变化会导致降水化学特征的协同变化。由于经济快速发展导致酸性物质排放（尤其是 NO）增加，以及城市化导致碱性离子浓度降低，都导致了深圳的雨水酸化趋势。
