Groundwater sampling techniques

There are several groundwater sampling techniques in use today. 

This chapter aims to provide a step-by-step guide for practitioners involved in the collection of contaminated samples by reviewing current groundwater sampling techniques and procedures and highlighting the major sources of uncertainty associated with sample collection. On-site water-quality measurements, quality assurance procedures and sample handling techniques designed to maintain the representativeness of the sample from field to laboratory are also discussed. 

Quinn, K., S. Wittmann and R. Lee. Use of Soil Gas Sampling Techniques for Assessment of Groundwater Contamination. In Management of Uncontrolled Hazardous Waste Site Proceedings, Hazardous Materials Control Research Institute, Washington, D.C., 1985. 

Evidence for the association of U with humic acids has been documented elsewhere. Dearlove et al. (1991) showed that U concentrated by ultrafiltration techniques from organic-rich groundwater samples were associated with humic colloids. Humic and fulvic acids have been shown to strongly complex U. Lienert et al. (1994) modeled the distribution of U species in the Glatt River and concluded that U-humate complexes become important at pH <6.8. These results reinforce the conclusions in the estuarine studies that U humate and fulvate complexes may account for the association of U with colloids. 

Kerfoot [6] examined the performance of a grab sampling technique for soil-gas measurement analyses, at a site with groundwater known to be contaminated with chloroform. The study assessed the correlation between soil-gas and groundwater analyses with chloroform as a model volatile organic compound. Chloroform concentration in soil gas increased linearly with depth in the unsaturated zone. 

Gustavson, K.E. and Haikin, J.M. 2000 Comparison of sampling techniques and evaluation of semipermeable membrane devices (SPMDs) for monitoring polynuclear aromatic hydrocarbons (PAHs) in groundwater. Environ Sci. Technol. 34 4445 451. 

For the detection, gas chromatography (GC) [15,18-20, 28] and liquid chromatography (LC) [14—16, 21, 22, 24, 26-29] coupled with mass spectrometry (MS) or tandem mass spectrometry (MS/MS) have been the techniques most frequently used in the determination of pesticides in ground water. Examples of the application of both techniques in the area of study, Catalonia, are the work of Garrido et al. [17], who used GC-MS and GC with electron capture detection (ECD) for the analysis of 44 pesticides in groundwater samples from Catalonia and that of Kampioti et al. [25], who used online SPE-LC-MS/MS to analyse 20 pesticides in river water and... 

The purpose of this chapter is not to promote the replacement of traditional physically based methods of assessing groundwater-lake systems with isotopic methods, but rather to demonstrate the utility of isotopic techniques. Physically based methods can provide more detailed information on the spatial and temporal variability of a groundwater-lake system than isotopic approaches can provide. Regardless of the method chosen, however, an adequate number of piezometers is necessary to ensure that groundwater samples are collected from upgradient areas. 

Groundwater sampling Subsurface characterization and monitoring techniques... 

In addition to colloidal particles, groundwater may contain coarser particles of clay, silt, and sand. These particles may precipitate in the sample container and form a visible layer of sediment at the bottom. The amount of sediment in a water sample often depends on the sampling technique and cannot be accurately reproduced. The... 

Groundwater refuses to submit to a regimented written procedure, and the sampling of it may be more of an art than science. The ability to bring groundwater to the surface and collect a representative sample depends on the experience, intuition, and individual sampling technique of the sampler. 

Hydride generation AAS is a well-established technique for the determination of selenium because of its selectivity and sensitivity. The detection limits are improved by concentrating the hydride prior to the transfer to the spectrometer. Cryogenic condensation in a U-tube at liquid nitrogen temperature is a preferred method of pre-concentration. However, selenium hydride is formed essentially only from Se. The selectivity for Se has been combined with various chemical preparation steps to determine the sum of SeIV and Se and the total selenium content of samples. Se concentrations are measured by the difference between the (Se + Se ) and Se contents. The difference between total selenium and (Se + Se ) contents represents the concentrations of Se° and Se2- species. These methods have been used for determinations of selenium species in natural waters. Soluble organic matter in some groundwater samples interferes with the hydride generation determination of selenium. Isolation of humic substances by their adsorption on resins has overcome this problem. 

Vroblesky, D.A. 2007. Passive diffusion samplers to monitor volatile organic compounds in groundwater. In R. Greenwood, G.A. Mills, and B. Vrana (eds), Passive Sampling Techniques in Environmental Monitoring, pp. 295-309. Amsterdam Elsevier. 

Stuart, A. (1984). Borehole sampling techniques in groundwater pollution studies. British Geological Survey Technical Report, WE/FL/84/15. 

Trick J. K., Stuart M., and Reeder S. describe the tools available to the field sampler for the collection of groundwater samples, methods of on-site water quality analysis, and the appropriate preservation and handling ofsamples. The authors discuss the merits of different purge methodologies and show how on-site measurements such as pH, specific electrical conductance (SEC), oxidation—reduction potential (ORP), dissolved oxygen (DO), temperature, and alkalinity can be used to provide a check on subsequent laboratory analyses. Techniques for the preservation and analysis of samples and quality assurance and quality control are also presented. 

The most common groundwater and gas sampling techniques in crystalline rock feature some form of downhole pumping device that lifts the fluid sample to the borehole collar, where standard flow cells and sophisticated sampling techniques are used to process the samples. A wide variety of devices and techniques are available and good reviews can be found in Bottomley et al. (1984), Ahnen et al. (1986),... 

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