旅游和区域大气污染对四川九寨沟气溶胶的贡献

2010年4月~2011年4月,在九寨沟连续监测了总悬浮颗粒物(TSP)和水溶性无机离子的浓度.结果表明:旅游活动显著增加了空气中TSP、SO42-、Ca2+、K+、NH4+和NO3-的含量,而Na+、Mg2+和Cl-则主要来自自然源;旅游强度最高时期(6~10月),降水对空气的清洗作用最强,气溶胶污染程度为全年最低;旅游强度较低时期(1~3、4~5和11~12月),降水量较低且西北沙尘易在春季抵达九寨沟,所以气溶胶污染程度较高;区域燃煤可能是气溶胶[SO42-]:[NO3-]比值较高的原因;生物质燃烧可能是K+在秋末至次年初春较高的原因之一.九寨沟大气环境已明显受当地旅游活动和污染物长距离传输的影响.

Contributions of local tourism and regional air pollution to atmospheric aerosols in Jiuzhaigou,Sichuan, China.

From April 2010 to April 2011, weekly to biweekly samples of total suspended particle (TSP) were collected at two sites in Jiuzhaigou National Nature Reserve (Jiuzhaigou hereafter). The site at the entrance was much more affected by local tourism (e.g., tour bus), compared with the site at the Long Lake meteorological station. Ionic concentrations of the samples were measured. The results show that TSP, SO42-, Ca2+, K+, NH4+ and NO3- concentrations in air were significantly higher at the entrance than at the Long Lake meteorological station, while Na+, Mg2+ and Cl- concentrations were similar between the two sites, respectively. Pronounced seasonal variations in ionic concentrations were observed. Concentrations of TSP and most ions were lower during the peak season of tourism (from June to October), probably due to the higher cleaning effect of precipitation on air. In contrast, concentrations of TSP and most ions were higher during the other months, likely owing to low precipitation amount and the spring dust from northwestern China. Furthermore, the equivalent ratios of [SO42-]:[NO3-] were relatively high. All above suggest that atmospheric environment in Jiuzhaigou was considerably polluted by local tourist activities, regional combustion of coal and biomass, and spring dust transported from northwestern China.