Monthly average concentrations

Similarly, Fig. 8.23 shows the monthly average concentrations of HCOOH, CH3COOH, HC1, and HNO-, measured at eight sites in southern California in 1986 (Nolte et al., 1997). Formic and acetic acids are seen to be the major acids, consistently exceeding HN03. 

Boudries et al. (1994) monthly average concentrations at Porspoder on the west coast, Brittany. Remote air masses were of oceanic origin. Those under rural-suburban were identified as being of continental origin. 

Figure 10.14 Monthly averaged concentrations of oxygen (g O2 m-2 d 1) and nutrient (NH4+, N02 , and NO3 ) (ixmolm-2 h-1) fluxes at Station DR7 in Mobile Bay (USA) from January 1993 to December 1994. Positive and negative values represent fluxes out and into the sediments, respectively. (Modified from Cowan et al., 1996.)...

The maximum turbidity permitted in drinking water is 1 TU. In industrial waters, turbidity is measured in milligrams per liter of suspended solids. For example, in the case of mining sedimentation ponds, the law permits a monthly average concentration of 35 mg L-1, with a maximum of 70 mg L"1. High concentrations of suspended solids are known to inhibit aquatic life. Also, colloidal matter is known to carry various inorganic and organic pollutants. 

FIGURE 1.11 Monthly average concentration of carbon dioxide in dry air observed at Mauna Loa Observatory, Hawaii from March 1958 to April 1995. Note The measurements were made with a continuously recording non-dispersive infrared gas analyzer. The smooth curve fit is a fit of the data to a four harmonic annual cycle which increases linearly with time plus a spline fit of the interannual component of the variation. From Whorf (1996). 

Releases to sewers—monthly average concentration 90Sr Class Df 5x1 O 6 iCi/mL NRC 2001g 10CFR20, Appendix B... 

Monthly Averaged Concentration Model (MAC) is designed to evaluate the environmental fate and human exposure of chemicals released into the terrestrial environment consisting of air and soil phases under monthly averaged site-specific conditions. 

The monthly average concentrations for release to sanitary sewers are applicable to the provisions in 20.1003. The concentration values were derived by taking the most restrictive occupational stochastic oral ingestion ALI and dividing by 7.3e6... 

One weakness of some multimedia models that must be considered by the user is inconsistency of time scales. For example, if we employ monthly averaged air concentrations to get rainout values on fifteen-minute interval inputs to a watershed model, large errors can obviously occur. The air-land-water-simulation (ALWAS) developed by Tucker and co-workers (12) overcomes this limitation by allowing for sequential air quality outputs to provide deposition data to drive a soil model. This in turn is coupled to a surface water model. 

A survey of the radon concentrations in a representative sample of more than 2000 dwellings in the UK has been completed and provisional results are now available. On average, concentrations are 29% lower in bedrooms than in living areas. The mean radon concentration weighted for room occupancy is 22 Bq m 3. Assuming an equilibrium factor of 0.35 and a mean occupancy of 75%, the mean annual exposure in UK homes is assessed as 0.08 Working Level Months (WLM) and the mean annual effective dose equivalent as 0.43 mSv. 

The measurements with the PRM was performed over the two years following the period mentioned above. The PRM was exposed for two months for each measurement. This approach gave an average concentration in two months. The results obtained in outdoor and indoor air were compared with the corresponding data from the PFC and the ERM. 

An international expert panel has issued an air quality criteria document for photochemical oxidants and related hydrocarbons that builds on the U.S. Department of Health, Education, and Welfare (dhew) air quality criteria document for photochemical oxidants. It discusses oxidant concentration patterns in the context of the same tabular material presented earlier. New information is added for the city of Delft the monthly means of daily maximums of hourly ozone concentrations are shown in Table 4-3, and the monthly average ozone concentrations are shown in Table 4-4. As in other cities, the worst month seems to be August, with a mean daily maximum (of hourly concentrations) of 0.071 ppm (140 Mg/m ). Table 4-5 compares the number of days in May through July 1971 when the ozone concentration at one or more sites reached or exceeded the hourly average of 200 Mg/m or of 100 Mg/m (from NATO data °). A comparison is made between Delft and five other monitoring sites in the Netherlands. Amsterdam had a peak value of 0.18 ppm in March 1971. 

TABLE 4-4 Monthly Averages of Ozone Concentrations in Delft, 1970 ... 

In a study of 13 workers exposed for 12 months to an average concentration of DDVP of 0.7 mg/m the eiythroqn e cholinesterase activity was reduced by approximately 35%, whereas the serum cholinesterase activity was reduced by 60%. The results of other tests and of thorough medical examination conducted at regular intervals were entirely normal." ... 

Rats exposed to the vapor of a mixture of hexa- and pentachloronaphtbalene at average concentrations of 1.16 mg/m for 16 hours daily up to 4.5 months showed definite liver injury, whereas 8.8mg/m produced some mortality and severe liver injury. ... 

FIGURE 14-20 Monthly average 03 concentrations at Mon-calieri, Italy Montsouris, France and Zagreb, Croatia in the 1868-1900 period and Arkona (Baltic Sea) in 1983 (adapted from Sandroni et al., 1992). 

To indicate numerically the correlation of trends for average monthly radon concentrations in air, nighttime atmospheric stability, and soil moisture content, coefficients for alternative simple empirical equations were obtained by least-square analysis ... 

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