Soils measurements

The major drawback to using the Florida study to support the correlation between indoor and soil measurements was that the indoor measurements were obtained from 3-day closed-house charcoal measurements, and soil radon was obtained from 1-month alpha track measurements buried 1 ft beneath the soil surface. Comparisons of charcoal and alpha track data are generally not recommended since they are quite different measurement techniques, and represent radon levels over different time periods. However, the study was subjected to numerous quality control checks including deployment of alpha track detectors in 10% of the houses to obtain a check on indoor air measurements made by charcoal canisters. In spite of the measurement drawbacks, the study indicates that soil radon measurements taken alone are not a dependable predictor of potential indoor radon concentration. 

Neill, C., Piccolo, M. C., Melillo, J. M., Steudler, P. A., Ceni, C. C. (1999). Nitrogen dynamics in Amazon forest and pasture soils measured by 15N pool dilution. Soil Biology Biochemistry, 31, 567-572. 

Direct measurements 1 Mediated direct measurements 1 Indirect soil measurements 1 Destructive soil analytical methods J Soil solution Soil solids... 

Soil pH is perhaps the most critical and common soil measurement where a definite amount of water is added before a measurement is made. Soil pH is a particularly complicated measurement because the proton can and does exist as a hydronium ion in the soil solution, as an exchangeable ion on the cation exchange sites, and bonded to various soil constituents. Because of these complexities, a soil sample is usually brought to a standard moisture content before a pH measurement is made. By bringing different soils to a common moisture content, they can be compared and analytical results from different laboratories will be comparable. Although there is a number of ways to measure soil pH, typically it is carried out using a pH meter and a pH electrode. 

The electrical characteristics, along with the salts, their movement through soil, and the diffuse double layer must be kept in mind when making any soil measurement using electricity or electrodes. 

Diagram an ISE electrode. What characteristics of ISE electrodes make them hard to use for direct soil measurements ... 

Explain and give examples of why voltammetry is not generally useful in direct soil measurement of components present. 

Q Basic soil measurement techniques and extraction procedures... 

Girvin, D.C. and Scott, A.J. Polychlorinated biphenyl sorption by soils measurement of soil-water partition coefficients at equilibrium, Chemosphere, 35 (9) 2007-2025. 1997. 

The estimated median concentration of 3,3 -dichlorobenzidine in sediments in the United States has been reported to be <1 ppm on a dry sediment basis (Staples et al. 1985). Of the 34 sediment or soil measurements recorded in the STORET database, none of the samples contained detectable concentrations of 3,3 -dichlorobenzidine. 

A number of other interesting possibilities for utilizing the excess 14C in the atmosphere as a tracer of natural processes come easily to mind. Not much is known about the rate of turnover of humus in the soil. Measurements of 14C in soil humus over the next several years, while the terrestrial biosphere continues to fix carbon with significant amounts of excess 14C, should help to determine the rate of turnover of carbon in the reservoir of humus. Some work along these lines is already in progress (41). 

Paul, E. A., Collins, H. E, and Leavitt, S. W. (2001). Dynamics of resistant soil carbon of Midwestern agricultural soils measured by naturally occurring 14C abundance. Geoderma 104(3-4), 239-256. 

Graustein, W.C. Turekian, K.K. (1986) 210Pb and 127Cs in air and soils measure the rate and vertical profile of aerosol scavenging. Journal of Geophysical Research, 91, 14355-66. 

This strategy is summarised in Box 1 illustrated by the example in Box 2. It is of course possible to make different types of cadmium in soil measurements. For example, instead of the total cadmium, the amount of cadmium extracted by a specific method, or the amount of cadmium in the sample as received, or dried in a different way could be measured. These are different measurements (measurands) and likely to give different measurement values, but all can be made traceable to SI, including the amount of substance. Hence the importance of adequately defining the measurand, in addition to establishing measurement traceability. 

The client requires to know the total amount of cadmium in soil, measured in mg/kg, on a dry weight basis. 

Girvin, D.C., Sklarew, D.S., Scott, A.J., Zipperer, J.P (1997) Polychlorinated biphenyl desorption from low organic carbon soils measurement of rates in soil-water suspension. Chemosphere 35, 1987-2005. 

Jenkinson, D. S. and Ladd, J. N. (1981). Microbial biomass in soil measurement and turnover, in Soil Biochemistry volume 5, (E. A. Paul and J. N. Ladd, Eds.). New York Marcel Dekker, 415-471. 

Inubushi, K., Brookes, P. C and Jenkinson, D. S. (1991). Soil microbial biomass C, N and ninhydrin-N in aerobic and anaerobic soils measured by the fumigation-extraction method. Soil Biol. Biochem. 23,737-741. 

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