Sample mean, total site area

The estimates of the sample mean (Br) and variance (Sr ) for each zone K can be Iculated based on the Nr measurements. The overall sample mean (E) for the total site area for each species of concern can then be calculated using... 

In total, 550 analyses were conducted from samples taken at this site. These data indicate that only 5.8 percent of the 10.9 acres contaminated represented the road surfaces originally sprayed. The remaining surface contamination probably resulted from dispersion by wind, vehicular traffic, runoff, etc. The total TCDD sprayed was probably about 340 grams, with 74 percent still on the areas sprayed. Mean, volume weighted, TCDD concentrations in the sprayed and dispersed areas were 469 and 31 ppb, respectively. Concentrations in individual composite samples collected from sprayed areas ranged up to 1,800 ppb. About 90 percent of the TCDD was contained in 13 percent of the soil volume. 

Since 1995, concentrations of PAHs have been reported for various sites along the South Korean coasts. Concentrations of total PAHs measured in freshwater sediment (n — 71) varied greatly with sampling station, ranging from 1.00 to 7685 ng g-1 dw, with regional means of 128-1282 ng g-1 dw at the sites. Relatively small concentrations have been found in Lake Shihwa sediment with a mean of 11 ng g 1 dw of total PAHs. Many studies reported the sedimentary PAHs in coastal bay areas, and their total PAHs (mean = 266 ng g-1, dw, n — 226) were similar to those measured in soil samples (mean = 255 ng g-1, dw, n — 216). The maximum concentration (3095 ng g-1 dw) of total PAHs in marine sediments was found in Ulsan Bay near a shipbuilding area. 

Wong and coworkers118 analyzed fish and other environmental samples (clam, macrophytes, sediments and waters) from areas upstream and downstream from alkyllead manufacturing sites beside the St. Lawrence and St. Clair Rivers, Ontario, and found a clear indication of elevated alkyllead levels in samples near the industries. Most species of fish contained alkyllead compounds with tetraethyllead and triethyllead as the predominant forms. Most fish from the contaminated areas contained 70% or more of the total lead as alkyllead. Average alkyllead levels varied from year to year but declined steadily after 1981. For example, the mean value of alkyllead in carp from the St. Lawrence River decreased from 4207 H g kg-1 in 1981 to 2000 H g kg-1 in 1982 and to 49 Xg kg 1 in... 

Several types of sampling tasks could involve various types of extraction at the sampling site. This would be the case in integrating sampling, where the mean concentration over a period or over an area is sought, or when a speciation sampling is attempted, i.e., where the aim is to determine not only total concentrations but also equilibria (dissolved-bound, different dissociation conditions, different redox conditions, etc.). 

The LT system was mobilized to the site after preparation of a detailed site specific Work Plan and Health and Safety Plan. An Air Permit was received from the Stanislaus County Air Resources Board. The soil was excavated from a 50 ft. by 50 ft. area. During treatment the treated soil was composited daily and analyzed using a Hanby Environmental Test Kit for petrolevim hydrocarbons. This simple test kit, which provides rapid soil analysis, was used as a means of process control. The processed soil operating temperature and retention time was optimized at 422°F and 22 minutes, respectively. The treated soil samples were collected and analyzed for TPH and BTEX s by an independent third party. The average of the 18 samples collected and analyzed using approved analytical techniques are provided on Table I. The treated soil exceeded the treatment criteria of 100 ppm total petrolevim hydrocarbons and 700 ppb toluene. 

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