Accuracy of Lysimeters for Dissolved Copper, Antimony, Lead, and Zinc Sampling under Small Arms Backstop

Abstract

Three assays were conducted to evaluate the reliability of lysimeters in detecting concentrations of Cu, Pb, Sb, and Zn in interstitial water of the vadose zone. Two box lysimeters (BLs) made from polyvinyl chloride (PVC) and polyvinylidene fluoride (PVDF) and three tension lysimeters (TLs) of different types were used. Assays were conducted with two concentrations of dissolved metals, undiluted and diluted in a 1:10 ratio, and at three different pHs. The assays were made to evaluate the sorption induced by the lysimeter material itself, by standard quartz sand added to the BLs, and by two types of glass beads placed around the porous cup of the TLs. Generally, BLs were more suitable for interstitial water sampling than TLs. Among the TLs, the one made of nylon was more reliable than the two others. Box lysimeters are a good choice to obtain accurate and comparable results for Cu, Pb, Sb, and Zn analysis. However, they have to be backfilled with natural soil found at the exact location of the lysimeter and not with standard quartz sand. Nylon TLs can also be used for water sampling for Sb, Pb, and Zn analysis but not for Cu. Glass beads may interact with dissolved metals and their use around the suction cup in TLs can be avoided by using the fine fraction of natural sediments (<125 μm) found at the location of the porous cup. Water samples from TLs do not need to be filtered for dissolved metal analysis because they are already filtered by the porous cup.

Soil solution data from Bohemian headwater catchments record atmospheric metal deposition and legacy pollution

“…Another external factor that may affect soil solutions would be direct absorption onto the nylon lysimeter samplers. But it has been determined that this factor has no effect on metal concentrations at pH < 5, i.e., LYS and NAZ, and would have only slightly decreased measured concentrations of elements such as Cr and Pb at pH ≥ 6 ( Wenzel et al 1997;Martel et al 2014)-i.e., only at the PLB site (Table 1).…”

“…They provide useful information to assess ecosystem input and output budgets. Tension lysimeters, on the other hand, allow comparing ion-exchange and/or uptake in relation to bedrock chemical weathering and elemental leaching (Goss et al 2010;Martel et al 2014;Makowski et al 2020). With awareness of this sampling-target difference, and consideration of the hydrochemical effects of Fig.…”