Non-urban sites

The carbon analyzer has been used to analyze filters from 42 urban sites and 22 non-urban sites in the United States. These filters were obtained from the National Air Surveillance Network (NASN) filter bank for 1975. Carbon concentrations and mass fractions for Detroit, Michigan, are shown in Figures 5 and 6. Both the organic and elemental carbon concentrations are highly variable, and no seasonal trends are apparent. For this site elemental carbon constituted 38% of total aerosol carbon. Typical values for other sites ranged between 35 and 55%. 

Andres-Hernandez, M. D., J. Notholt, J. Hjorth, and O. Schrems, A DOAS Study on the Origin of Nitrous Acid at Urban and Non-Urban Sites, Atmos. Environ., 30, 175-180(1996). 

In Table VIII the annual averages of nickel at selected NASN urban sites are presented. Here the extreme case is in East Chicago where the low of 35 of 154 are approximately within a factor of two of the five-year average of 76. All of the five-year averages lie between 60 and 100 ng/m . At selected non-urban sites where minimum detectable concentrations can be expected (Table IX), we find a seasonal variation to be meaningless in some instances because the minimum detectable values... 

Table IX Seasonal Variation in Nickel Concentrations at Some NASN Non-Urban Sites ...

That fallout of trace elements from atmospheric pollution is widespread and far from confined to urban and industrial areas, is also borne out by data published by the UK Atomic Energy Authority, who determined, by neutron activation analysis, about 30 trace elements in airborne dust, rainwater and dry deposition, sampled at regular intervals in north-west England [188]. The highest concentrations measured in air were for chlorine, sodium, calcium, aluminium, iron, lead and zinc, and there were also measurable levels of antimony, arsenic and mercury, usually in the winter months, when there was a general increase in trace-element concentration. Further data were published on the atmospheric content and total deposition of a wide range of trace elements at seven non-urban sites (one in Shetland) in the UK in the years 1972 and 1973 [189]. Data have also been published for the North Sea and the Firth of Clyde [190]. 

Noll KE, Draftz R, Fang KYP. The composition of atmospheric coarse particles at an urban and non-urban site. Atmos Environ 1987 21 2717-2721. 

Fogwater collected at non-urban coastal sites was usually acidic (pH range 3 to 7). Impact of emission centers on distant coastal locations was documented. The low alkalinity of marine atmospheres make them particularly... 

Both categories of customers desire limited capital outlay, rapid site assembly and early initiation of a revenue stream, outsourcing of the front end and back end fuel cycle and waste management services, reduced operational staffing requirements, near-urban siting based on unprecedented levels of safety and robustness with respect to equipment malfunction and/or human error, and a non-nuclear safety grade balance of plant. 

Very early on, Aitken (1923) showed that most particles in the atmosphere are smaller than 0.1 pm diameter and that their concentrations vary from some hundreds per cm over the ocean to millions per cm in urban areas. Junge (1955,1963,1972) measured the atmospheric aerosol number size distribution and concentration in urban and non-urban areas as functions of altitude and site. He established the standard form for plotting size distribution data log of AN/ADp versus logD, where N = number and Dp = particle diameter. He observed that this plot was a straight line that could be described by the equation AN/ADp = AD, where A and k were constants. He also noted that in the range from 0.1 to 10.0 pm particle diameter, k was approximately equal to 4.0. This distribution mode was widely known as the Junge distribution or the power law distribution. 

Air quality assessment is undertaken with different levels of detail in the Member States. There are also indications that assessment is incomplete in some zones. The analysis of non-critical areas has shown that for some cities only information about urban background stations is available and that the data in AirBase are different from other datasets. Whereas compliance is achieved in urban background areas, exceedances might occur at hotspot sites, which may remain undetected if no further assessments are undertaken. Therefore guidance documents and further support, e.g. via dedicated workshops, might be helpful. 

Amendments in 1987 authorized measures to address non-point source pollution (storm water runoff from farm lands, forests, construction sites and urban areas), now estimated by the states to represent the largest remaining water pollution problem in the USA (USEPA, 2000). Because of this, although toxics remain a significant component in the mix of non-point runoff, other major pollutants such as nutrients have risen to the fore of public concern for action. Presently the major thrust in implementation of the CWA is to manage on a watershed basis and integrate all parts of the CWA to operate in an integrated fashion, instead of in isolation. 

We were anxious to evaluate the use of supercritical carbon dioxide (scCOj) to remediate an urban soil. A two-stage approach was prompted by our efiforts to make the process continuous. SCCO2 extraction of particulate media is inherently a batch process. Pressure within the extractor is maintained with a capillary restrictor (in our case a 50 pm diameter silica tube) that is prone to fouling. The non-polar organic Section of an aqueous (surfactant) extract can be removed continuously (either on site or off site) with scCOj in a counter current liquid-liquid like process. The heavy metal contaminants remain with the water fraction for subsequent treatment. The organics fraction is the subject of this short review on SCCO2 processing. 

To control the sea surface pollution, essentially by urban sewage, a simple indicator obtained by counting the colonies of luminescent and non-luminescent bacteria developing on filters, a solid culture medium, was applied [312]. Results from a reference area and polluted sites, and their variations during the year are reported. This method allows to assess the pollution degree and the area of the polluted sites to give recommendations on cleaning. 

The final goal of the presented procedure is to estimate PAH deep seepage at urban and industrial sites. The evaluation should be plausible and therefore rely on a process-based model for the transport of reactive solutes through unsaturated porous media. After we succesfully managed to reconstruct possible soil profiles by means of a conditional stochastic simulation based on Markov theory, we now have to run the process-based reactive transport model (PBRTM) for all combinations obtained by the stochastic simulation. As PBRTM we used the model CARRY (Totsche et al., 1996 Knabner et al., 1996), in its current Version 5.5, which allows to model reactive transport of hydrophobic organic contaminants, for example PAH, in layered soils under unsaturated flow conditions. CARRY considers linear and non-linear, equilibrium and non-equi-... 

Table 6.8 tabulates air lead data for non-U.S. urban areas and rural around the globe. Locations, year(s) of measurement, and reported air lead concentration summaries are given. The earliest of the years monitored for each national locale in Table 6.8 show quite high air lead, compared to U.S. data shown in the earlier tables for about the same time period. Sites in Italy, Saudi Arabia, and Greece had particularly elevated air lead, ranging from 3.2 to 5.5 p.g/m. In most cases where multiple years of measurement were noted, declines in air lead are seen post-1979. Table 6.8 also shows that size of urban area or... 

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