Baumgardner Ralph E, Isil Selma S, Bowser Jon J, Fitzgerald Kelley M
a U.S. Environmental Protection Agency, National Exposure Research Laboratory , Research Triangle Park , North Carolina , USA.
b QST Environmental Inc , Gainesville , Florida , USA.
J Air Waste Manag Assoc. 1999 Nov;49(11):1266-1279. doi: 10.1080/10473289.1999.10463966.
The Clean Air Status and Trends Network (CASTNet) was implemented by the U.S. Environmental Protection Agency (EPA) in 1991 in response to Title IX of the Clean Air Amendments of 1990, which mandated the deployment of a national ambient air monitoring network to track progress of the implementation of emission reduction programs in terms of deposition, air quality, and changes to affected ecosystems. CASTNet evolved from the National Dry Deposition Network (NDDN). CASTNet currently consists of 45 sites in the eastern United States and 28 sites in the West. Each site measures sulfur dioxide (SO), nitric acid (HNO), particle sulfate (SO), particle nitrate (NO ), and ozone. Nineteen sites collect precipitation samples. NDDN/CASTNet uses a uniform set of site-selection criteria which provides the data user with consistent measures to compare each site. These criteria also ensure that, to the extent possible, CASTNet sites are located away from local emission sources. This paper presents an analysis of SO and SO concentration data collected from 1987 through 1996 at rural NDDN/CASTNet sites. Annual and seasonal variability is examined. Gradients of SO and SO are discussed. The variability of the atmospheric mix of SO and SO is explored spatially and seasonally. Data from CASTNet are also compared to SO and SO data from concurrent monitoring studies in rural areas.
清洁空气状况与趋势监测网络（CASTNet）由美国环境保护局（EPA）于1991年设立，以响应1990年《清洁空气修正案》第九条的要求。该条款规定要部署一个全国环境空气监测网络，以追踪减排计划在沉降、空气质量以及受影响生态系统变化方面的实施进展。CASTNet由国家干沉降网络（NDDN）发展而来。目前，CASTNet在美国东部有45个站点，西部有28个站点。每个站点都测量二氧化硫（SO）、硝酸（HNO）、颗粒态硫酸盐（SO）、颗粒态硝酸盐（NO）和臭氧。19个站点采集降水样本。NDDN/CASTNet采用一套统一的选址标准，为数据使用者提供可用于比较各站点的一致测量数据。这些标准还确保CASTNet站点尽可能远离本地排放源。本文对1987年至1996年期间在农村NDDN/CASTNet站点收集的SO和SO浓度数据进行了分析。研究了年度和季节变化情况。讨论了SO和SO的梯度。从空间和季节角度探讨了SO和SO大气混合物的变异性。还将CASTNet的数据与农村地区同期监测研究中的SO和SO数据进行了比较。
