Artifacts Caused by Collection of Soil Solution with Passive Capillary Samplers

Abstract

Soil solution was collected with passive capillary samplers of sampling is unknown and may change with varying (PCAPS) and zero-tension samplers (ZTS) from A horizons of forested soils. The volume and chemistry of collected solutions were moisture conditions or suction applied. In addition, sucmeasured weekly during discrete seasonal collection periods. Acidtion must be applied manually to the sampler several washed PCAPS increased alkalinity (3-fold), pH (1-3 units), and hours or days prior to solution collection. This is probconcentrations of Ca (2-fold), Na (8-fold), and Si (4-fold), relative to lematic because the magnitude of tension exerted on ZTS solutions. Aluminum concentrations were dramatically reduced soil water gradually decreases over time. Lastly, because in PCAPS compared with ZTS samples. Differences in solution chemof the small cross-sectional area of the cup, multiple istry were attributed to leaching and weathering of fiberglass wicking samplers are required to represent adequately soil varimaterial utilized in the PCAPS. In addition, PCAPS collected greater ability (Barbee and Brown, 1986). volumes (normalized by sampler area) of solution relative to ZTS in Brown et al. (1986) first introduced passive capillary weak-structured sandy loam soil due to a preponderance of matrix flow. The results indicate that the PCAPS used in this study are not samplers (PCAPS) to provide an alternative means of suitable for aqueous geochemical studies of dilute soil solutions. sampling soil water in the field. As a result of their high conductivity and the tension exerted, PCAPS collect matrix and macropore flow under both saturated and

Colloid-Facilitated Transport of Radionuclides through the Vadose Zone

“…2). This corroborates the findings of Goyne et al (2000) and Brahy and Delvaux (2001) of cations sorbed to the wick surface. The measured and modeled water retention characteristics of the fiberglass wick are shown in Fig.…”

“…We L Ϫ1 colloid suspension for two to four pore volumes. Effluent pH was determined with a pH meter, and colloid concentratreated the wick with a procedure described by Goyne et al (2000). The wicks were first cut into 77-cm-long pieces, weighed, tions were determined spectrophotometrically at 300-nm wavelength, except the ferrihydrite, which was measured at and rinsed extensively with deionized water and combusted in a kiln at 400ЊC for 4 h. The wicks were weighed after combustion 214 nm.…”

“…An access trench is excavated along the study site with horizontal tunnels to install the PCAPS. The use of PCAPS in vadose zone sampling has been studied in detail with respect to solute and flux sampling (Holder et al, 1991;Poletika et al, 1992;Boll et al, 1992;BrandiDohrn et al, 1996;Goyne et al, 2000;Louie et al, 2000;Gee et al, 2002Gee et al, , 2003 and also with respect to mobileimmobile pore water (Landon et al, 1999). We assumed a priori that passive capillary samplers (PCAPS), as opposed to suction and zero-tension samplers, have the best chance of yielding a representative sample for reasons described below.…”

Overview of Selected Soil Pore Water Extraction Methods for the Determination of Potentially Toxic Elements in Contaminated Soils: Operational and Technical Aspects

“…Depending on the cup material (materials used include aluminium oxide, glass sinter, ceramic, teflon, acrylic copolymer with internal nylon support, stainless steel, plastic 'organic' polymers -PVC, PP, PVDF) additional reactions may take place leading to absorption, precipitation or even release of chemical substances, resulting in pronounced effects on the final composition of the water sampled (Litaor, 1988). Several studies have investigated these effects and questioned the validity of results given by these kinds of samplers (e.g., Hansen and Harris, 1975;Levin and Jackson, 1977;Nagpal, 1982;Guggenberg and Zech, 1992;Goyne et al, 2000). Siemens and Kaupenjohann (2003) found that between 0.8 and 63 mg L -1 of dissolved organic carbon (DOC) was released from sealing and glues of pore water samplers.…”

Colloid-Facilitated Transport of Radionuclides Through The Vadose Zone

“…To further remove carbonates and combustion residue, the fiberglass wicks were soaked in a 10 mM HNO 3 solution bath, as described by Goyne et al (2000). Once the pH stabilized at the initial concentration of nitric acid (typically pH of approximately 2), double-deionized water was substituted for the nitric acid bath solution.…”