| 江淮地区湿沉降对颗粒物清除能力的影响 |
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| 引用本文： | 耿天召,童欢欢,赵旭辉,朱余.江淮地区湿沉降对颗粒物清除能力的影响[J].环境科学研究,2019,32(2):273-283. |
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| 作者姓名： | 耿天召 童欢欢 赵旭辉 朱余 |
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| 作者单位： | 安徽省环境监测中心站,安徽 合肥,230031;合肥工业大学资源与环境工程学院,安徽 合肥,230009 |
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| 基金项目： | 安徽省公益性研究联动计划项目（No.1704f0804056）；安徽省省级环境保护科研项目（No.2016-04） |
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| 摘 要： | 为了解单次降水总量、降水时长、降水前颗粒物质量浓度对颗粒物清除能力的影响，对江淮地区2017年气象资料与颗粒物质量浓度资料展开分析.分析江淮地区2017年ρ（PM2.5）、ρ（PM10）及降水特征，综合对比各季节不同单次降水总量对颗粒物的清除能力，对比不同季节、不同降水时段对颗粒物清除能力的变化特征，以及不同季节降水前颗粒物质量浓度与清除率对应阈值关系.研究表明:江淮地区北部颗粒物质量浓度高于南部，南部单次降水总量和降水总时长较北部高.单次降水总量越大对颗粒物的清除率越高.当单次降水总量大于1.5 mm时，清除率提升最明显，并且秋、冬两季清除率高于春、夏两季；当单次降水总量低于1.5 mm时，春、夏两季清除率高于秋、冬两季.总体上，降水对PM10的清除率高于对PM2.5.降水时长对颗粒物的清除率具有明显的季节性变化特征.春、秋两季存在降水时长阈值，分别为10和20 h.春季低于该阈值（10 h）清除率为正清除率，高于该阈值清除率为负清除率；秋季低于该阈值（20 h）清除率为负清除率，高于该阈值为正清除率.夏、冬两季总体表现为正清除率.分析降水前颗粒物质量浓度对清除率的影响得知，降水对PM2.5清除率由负转正的阈值较PM10低，并且冬、春两季清除率阈值较夏、秋两季高，春季、夏季、秋季、冬季的ρ（PM2.5）清除率阈值分别为35、15、25、30 μg/m3，ρ（PM10）清除率阈值分别为60、50、60、60 μg/m3.单次降水过程中颗粒物所处高度由2 200 m降至1 000 m，并且此次降水对非球形粒子清除效果明显，粒径在2.5 μm以下粒子质量浓度显著下降，其中，粒径在0.7~1.2和1.5~2.5 μm粒子数浓度下降明显；另外，降水对颗粒物中NO3-和NH4+去除明显，并且降水后光学EC、光学OC及金属元素质量浓度和占比显著增长.研究显示，当冬季单次降水总量大于1.5 mm，降水前ρ（PM2.5）大于30 μg/m3、ρ（PM10）大于60 μg/m3时颗粒物的清除率最佳.
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| 关 键 词： | 降水 颗粒物 清除率 |
| 收稿时间： | 2018/3/22 0:00:00 |
| 修稿时间： | 2018/10/14 0:00:00 |
Effect of Wet Deposition on the Removal Efficiency of Particulate Matter in the Yangtze-Huaihe Region |
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| GENG Tianzhao,TONG Huanhuan,ZHAO Xuhui and ZHU Yu.Effect of Wet Deposition on the Removal Efficiency of Particulate Matter in the Yangtze-Huaihe Region[J].Research of Environmental Sciences,2019,32(2):273-283. |
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| Authors: | GENG Tianzhao TONG Huanhuan ZHAO Xuhui and ZHU Yu |
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| Affiliation: | 1.Anhui Environmental Monitoring Center, Hefei 230031, China2.School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China |
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| Abstract: | The aim of this study is to evaluate the meteorological factors and particulate matter concentrations in the Yangtze-Huaihe Region in 2017 through investigating the effects of the amount of single precipitation, precipitation duration and pre-precipitation particulate matter concentrations on the removal capacity of particulate matter. This research investigated ρ(PM2.5), ρ(PM10) and precipitation characteristic of the Yangtze-Huaihe Region of 2017. Through comprehensive investigation comparison and analysis of particulate matter removal ability from different amount and period of precipitation in different seasons were performed. The concentration threshold of PM2.5 and PM10 and removal ability were also analysied. The results of this study suggested that the pollution in the northern part of the region was more severe compared to the southern part of the region. The total amount of precipitation and precipitation duration in the southern part were higher compared to the northern part of the region. A positive and significant correlation was observed between the clearance rate and growth of precipitation, and the effect of precipitation clearance increased with increase in the level of cumulative precipitation. When the amount of single precipitation was below 1.5 mm, the removal efficiency was higher in spring and summer and lower for autumn and winter. However, when the amount of single precipitation was higher than 1.5 mm, the removal efficiency in autumn and winter were higher and lowered for spring and summer. It was evident that precipitation duration had different seasonal variations on particulate matter removal efficiency. Duration thresholds in spring and autumn were noted to be 10 and 20 h respectively. When the precipitation duration was lower than the threshold level in spring, the clearance rate was positive while it had negative clearance rate when precipitation duration exceeded the threshold level. When the precipitation duration was lower than the threshold level in autumn, the clearance rate was observed to be negative, while a positive clearance rate was noted when precipitation duration exceeded the threshold level. In general, clearance rate was observed to be positive in summer and winter. It shows that PM2.5 clearance rate from negative to positive was lower than that of PM10, and the threshold values of winter and spring were higher compared to the values in summer and autumn. The threshold values of PM2.5 in spring, summer, autumn and winter were 35, 15, 25, 30 μg/m3 and 60, 50, 60, 60 μg/m3 respectively. During a single precipitation process, the altitude of the particulate matter decreased from 2200 to 1000 m, and the removal efficiency of the non-spherical particles was more evident. The mass concentration of the particles with the diameter below 2.5 μm was evidently reduced, the number concentration of particles with the diameter of 0.7-1.2 and 1.5-2.5 μm was significantly reduced. In addition, the precipitation removal of NO3- and NH4+ in particulate matter was apparent, and there was a significant increase in optical EC, optical OC, and metal elements after precipitation. The results of this study suggests that in winter if the total amount of single precipitation is greater than 1.5 mm, ρ(PM2.5) is more than 30 μg/m3 or ρ(PM10) is more than 60 μg/m3, it will have the best removal ability. |
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| Keywords: | precipitation particulate matter clearance rate |
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