Sampling of groundwaters

Reliable groundwater sampling usually requires a permanent in-flow or through-flow of water. Only exceptionally, samples from places which do not satisfy this requirement are necessary in order to identify processes of conditioned stagnation. 

It is recommended to take samples from a spring when pumping experiments take place, and after rain so that constant water quality can be determined, or pollution by surface water. 

Useful information can be obtained by taking a sample from a well during summer droughts when the consumption and exchange of water are maximum. 

Samples from drills (probes) are taken by a narrow deep sampling device or a pump. The samples from drills in which water has been present for a long time or whose outlet was not well closed ar.e not reliable. 

Drainage water is sampled into a sample container directly from the drainage outlet. 

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With the acceptable concentrations of herbicides in drinking water being taken to very low levels by some regulatory authorities (e.g., the EC), there has been interest in very low levels of atrazine present in some samples of groundwater and in drinking water. This finding illustrates the point that mobility of pesticides becomes increasingly evident as sensitivity of analysis improves. 

Gypsum is a relatively soft rock made of calcium sulfate. Rainwater percolates through g q)sum, dissolves some of the rock, and eventually becomes saturated with Ca ions and SOq ions. A geochemist takes a sample of groundwater from a cave and finds that it contains 8.4 X 10 M SO4 and 5.8 X 10 M Ca. (The ratio is not 1 1 because other sulfate rock contributes some of the SOq ions to the solution.) Use these data to determine the solubility product of calcium sulfate. 

Samples of groundwater were obtained from piezometers installed at various locations throughout the tailings. Groundwater was retrieved using a baler. Pore water was squeezed from samples of solid tailings. All water samples were analysed for cations, anions, Eh and pH. 

Spliid and Kpppen described a method using LLE and LC-APCI-MS for the analysis of water. The method proposed was then used to investigate the contamination of Danish ground-water with pesticides. More than 200 samples of groundwater collected from various areas of the country were analyzed. Metramitron was detected one or more times in concentrations ranging from the detection limit level to 19 /rg/L (32). 

Fig. 9.14 Lines of equal <5D values for Europe, based on over 300 samples of groundwater. A trend of lighter isotopic composition is seen as a function of the distance from the ocean, reflecting the continental effect in the precipitation. (After Sonntag et al., 1979.)...

Harrison I, Leader RU, Higgo JJW, et al. 1994. Determination of organic pollutants in small samples of groundwaters by liquid-liquid extraction and capillary gas chromatography. J Chromatogr A688 181-188. 

Figure 2. Map of arsenic distributions in groundwater from Bangladesh. The map shows a smoothed distribution determined by disjunctive kriging on 3207 samples of groundwater (<150 m depth, Gaus et al, 2001). Insets are frequency histograms of the concentrations of arsenic (pg F ) in groundwater from three selected study areas analysed in more detail...

Samples of [S- CH ] aldicarb, aldicarb sulfoxide and aldicarb sulfone were incubated with samples of groundwater and aquifer sediments to examine the potential for microbial degradation in situ in groundwater. The [S - XH3] aldicarb was provided by Union Carbide Agricultural Products Company the labeled sulfoxide was prepared from this by oxidation with hydrogen peroxide, the sulfone from the aldicarb by oxidation with peroxyacetic acid. These oxidants afforded better yields of cleaner product than the nr chloroperoxybenzoic acid previously used (18). 

Table VI shows examples of laboratory-measured and the substantially higher calculated in situ alkalinities for 10 samples of groundwater from Field 6. The values shown in Figs. 5 and 6 are laboratory, not in situ pH and alkalinities. Higher in situ pH and alkalinity would lead to faster rates of aldicarb residue breakdown. Projections of aldicarb residue degradation by alkaline hydrolysis should be based on in situ pH, alkalinity and temperature. These, like the residue concentrations, vary widely, spatially and temporally.

Recent sampling of groundwater at the Dalecarlia Reservoir has found perchlorate, nitroglycerin, and carbon tetrachloride. These compounds were widely used at the AUES, giving further evidence that buried contaminants can enter the groundwater and break out into the surface water. 

In a reanalysis of published data, Hess et al. (1985) reported a geometric population average of 187 pCi (6.9 Bq) radon-222/L of water in over 6,000 samples of groundwater supplies for public use. In contrast, samples of surface water supplies indicated that the average level of radon was 1 pCi (0.037 Bq) radon-222/L of water. 

Between 1980 and 1988, 3255 samples of surface water in EPA s STORET database were analyzed for 1,1,2-trichloroethane (STORET 1988). Ten percent of the samples contained the chemical at 10 parts per billion (ppb) or higher. A maximum level of 18,000 ppb was reported in 1982. The maximum concentration of 1,1,2-trichloroethane reported for subsequent years ranged from 10 to 125 ppb. Of the 22,615 samples of groundwater in the database, 10% were above 3 ppb. The maximum concentration of 1,1,2-trichloroethane in a groundwater was 350,000 ppb, reported in 1985. For the other years, the maximum concentration reported ranged from 18 to 1800 ppb. Unfortunately, the detection limit is apparently recorded in STORET when no chemical is detected, so it is impossible to say whether the 90 percentile figure represents positive samples or merely higher detection limits. 

Consider how the priority pollutant VOC trichloroethylene or trichlor-oethene, abbreviated TCE, is distributed between a sample of groundwater and the headspace in a sealed HS vial as shown schematically by ... 

Let us return to Eq. (3.27) and briefly consider the second factor, the phase ratio p, in the headspace sampling of groundwater to determine trace concentrations of VOCs in the environment. Kolb and Ettre have studied the influence of p on HS sensitivity. For a fixed temperature and fixed original concentration of VOC in the aqueous phase, C , the influence of changing p from, for example, 4.00 (only 20% of the total volume of the HS vial contains the sample) to p = 0.250 (80% of the total volume of the HS vial contains the sample) depends on the magnitude of For nonpolar... 

A sample of groundwater heavily contaminated with soluble inorganic iron is brought to the surface and the alkalinity is determined without exposing the sample to the atmosphere. Why does a portion of such a sample exposed to the atmosphere for some time exhibit a decreased alkalinity ... 

DPAA in humans has also been investigated. Kinoshita et al. [44] tested different columns and mobile phases for the detection of phenylarsenic compounds in urine from patients, mice and environmental samples of groundwater... 

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