A MODEL OF ENVIRONMENTAL BEHAVIOR OF CONTAMINATED DUST AND ITS APPLICATION TO DETERMINING DUST FLUXES AND RESIDENCE TIMES
A MODEL OF ENVIRONMENTAL BEHAVIOR OF CONTAMINATED DUST AND ITS APPLICATION TO DETERMINING DUST FLUXES AND RESIDENCE TIMES
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DOI：
10.1016/1352-2310(94)90044-2
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发表时间：
1994-02-01
影响因子：
5
通讯作者：
HEWITT, CN
中科院分区：
文献类型：
--
作者：
ALLOTT, RW;KELLY, M;HEWITT, CN
一个模型已被开发来描述的时间行为的巴罗因弗内斯，英格兰西北部的城市环境内的污染物示踪剂的浓度。使用的示踪剂是铯-137，主要来自1986年5月3日切尔诺贝利反应堆事故（1986年4月28日）放射性云的湿沉降。Cs-137活动沉积在这一主要事件补充了一个小的二次大气沉积输入的再悬浮活动。该模型进行了验证，对测量的时间行为Cs-137在城市灰尘中的两个室外水库，其中唯一观察到的输入的灰尘和活动是由大气沉积。对其他储存库（室外和室内）的进一步模拟研究证实，存在着额外的灰尘和活动输入通量;其中最重要的是土壤的机械迁移和建筑材料的降解（室外）以及室外灰尘和土壤的机械迁移和有机材料的掺入（室内）。该模型能够估计这些额外通量的大小，并计算平均尘埃质量停留时间（室外，250 +/- 110 d;室内29 +/- 1 d，表明保守的尘埃污染物预计在城市水库中保留的时间长度，在主要污染事件之后没有二次输入。这些停留时间对应于室外170 +/- 70 d和室内20 +/- 1 d的环境半衰期，对于仅接收污染物的单一主要输入的水库。当污染物发生二次输入时，如再悬浮活动的大气沉积或室内受污染粉尘的机械运输，污染物的平均环境半衰期增加50%，室外灰尘水库和室内水库超过18倍。这种室内灰尘的再污染对消除污染方案有影响，因为应注意降低室外污染水平，以确保通过清洁降低室内污染物水平的努力是有效的。
A model has been developed to describe the temporal behaviour of the concentrations of a pollutant tracer within the urban environment of Barrow-in-Furness, NW England. The tracer used was Cs-137 derived primarily from wet deposition, on 3 May 1986, of the radioactive cloud from the Chernobyl reactor accident (28 April 1986). The Cs-137 activity deposited during this primary event was supplemented by a small secondary atmospheric deposition input of resuspended activity. The model was validated against the measured temporal behaviour of Cs-137 in urban dust for two outdoor reservoirs in which the only observed input of dust and activity was by atmospheric deposition. Further modelling studies on other reservoirs (both outdoors and indoors) confirmed the existence of additional input fluxes of dust and activity; the most significant of these being the mechanical transport of soil and degradation of construction material (outdoors) and the mechanical transport of outdoor dust and soil and incorporation of organic material (indoors). The model enabled estimates of the magnitudes of these additional fluxes to be made and mean dust mass residence times to be calculated (outdoors, 250 +/- 110 d; indoors 29 +/- 1 d, indicating the length of time that conservative dust-bound pollutants would be expected to remain in urban reservoirs with no secondary inputs following the primary contamination event. These residence times correspond to environmental half-lives of 170 +/- 70 d outdoors and 20 +/- 1 d indoors, for reservoirs which only receive a single primary input of a contaminant. Where secondary inputs of pollutants occur, such as the atmospheric deposition of resuspended activity or the mechanical transport of contaminated dust indoors, the mean environmental half-lives of the pollutants increase by 50% for outdoor dust reservoirs and over 18-times for indoor reservoirs. This re-contamination of indoor dusts has implications for decontamination programmes in that attention should be paid to reducing outdoor contamination levels to ensure that attempts to reduce the levels of a pollutant indoors by cleaning are effective.