Lysimeter for collecting chemical samples from the vadose zone

摘要

A lysimeter has an elongated, relatively narrow sample pipe with flanges at upper and lower ends. A lysimeter assembly is connected to the lower end of the sample pipe by connecting an upper end of a central tube in the assembly to a lower end of the sample pipe. A circular lysimeter pan extends around the central tube. Vertical slits in the central tube provide a screen to permit water flow into the central tube from the pan but to prevent granular materials from the filter pack. Vertical webs in the pan rigidify the pan, and radial supporting webs and a ring beneath the pan support the pan. A relatively large diameter collection chamber has a spheroidal lower end and an upper end which receives the ring for centering the lysimeter pan at the upper end of the collection chamber. An outward and upward sloping flange at an upper end of the collection chamber with an elastic seal supports the lower conical wall of the lysimeter pan. A wick in the pan extends through slits in the central tube to wick water from the pan into the central tube and to flow water down along the inner wall of the central tube. The bottom of the central tube is open and is sloped, and an upward opening inner groove is formed around the lower end of the central tube. A drain tube is connected to a lower portion of the groove. A sampler is raised and lowered and positioned by a rod or chain extending through the sample pipe and central tube, so that a funnel at the upper end of a flask is aligned with the drain tube. Drain openings are provided in the canister bottom.