Rural background environments

The most simple and widely used spatial increment approach compares concentration levels measured in different environments, assuming that the actual level at a given site is the sum of emissions released on regional, urban, and local scales (cf. Fig. 2). Hence, by calculation of the spatial increments (e.g. traffic-urban background, urban background-rural background) basic assessments of the shares of emissions from the different source areas can be obtained. This approach constitutes the first step within a source apportionment method first proposed by Lenschow et al. [3]. 

Table II. Estimates of Annual Dry Deposition For Rural/Background Areas in the West (After Hidy Young, Environ., Res. Tech., unpublished report)...

Doherty RE (2000a) A history of the production and use of carbon tetrachloride, tetrachloroethyl-ene, trichloroethylene and 1,1,1-trichloroethane in the United States. Part 2. Trichloroethylene and 1,1,1-trichloroethane J Environ Forensics 1 83-93 Doherty RE (2000b) A history of the production and use of carbon tetrachloride, tetrachloroethylene, trichloroethylene and 1,1,1-trichloroethane in the United States Part 1. Historical background carbon tetrachloride and tetrachloroethylene. J Environ Forensics 1 69-81 Dorsch MM, Scragg RK, McMichael AJ, Baghurst PA, Dyer KF (1984) Congenital malformations and maternal drinking water supply in rural South Australia A case-control study. Am J Epidemiol 119 473-86... 

Yin J, Harrison RM, Chen Q, Rutter A, Schauer JJ (2010) Source apportionment of fine particles at urban background and rural sites in the UK atmosphere. Atmos Environ 44 (6) 841-851... 

Simoneit, B.R.T., and Mazurek, M.A. (1982) Organic matter of the troposphere—II. Natural background of biogenic lipid matter in aerosols over the rural western United States. Atmos. Environ. 16, 2139-2159. 

Roberts JM, Hutte RS, Fehsenfeld FC, et al. 1985. Measurements of anthropogenic hydrocarbon concentration ratios in the rural troposphere Discrimination between background and urban sources. Atmos Environ 19 1945-1950. 

In air, arsenic is present mainly adsorbed onto particulates as a mixture of As " and As , with background levels in Europe currently estimated as 0.2-1.5 ng m in rural areas, 0.5-3 ngm in urban areas, and maximally 50 ng m in industrial areas (DG Environment 2000). As early as the late 1980s, it was reported that very high arsenic levels up to around 30 mg m in former years found in the air of copper smelters had almost disappeared. Controls in the USA in formerly highly loaded industrial zones showed average As levels below the ACGIH threshold limit value (TLV) proposed at that time of 0.5 mg As m (Iffland 1994). 

A proportion of the atmospheric content of trace elements produced in urban areas must be deposited in areas downwind, so that there must also be a general background of contamination at a much lower level in soils in rural areas in industrialised and densely- populated countries. Some fallout can also be expected in nearby seas of even in other countries beyond, and Tyler [167] states that the high concentrations of cadmium and lead in the moss carpets of southern Norway and south-western Sweden, reflect an atmospheric deposition ofithese elements transported from remote sources, probably from continental Europe and the UK. Fallout from atmospheric pollution into the sea is unlikely to produce high local concentrations of any potentially toxic element. Dispersion of trace elements in the environment by this particular route is more efficient than by any other and no pollution problems have been reported as having arisen in this way. 

Putaud, J.P., et al., European aerosol phenomenology-2 Chemical characteristics of particulate matter at kerbside, urban, rural and background sites in Europe. Atmospheric Environment, 2004.38(16) 2579-2595. 

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