Precision Ground Water Sampling in Coastal Aquifers Using a Direct‐Push, Shielded‐Screen Well‐Point System

Abstract

Abstract Conventional ground water sampling methods are often expensive and lack the sampling resolution required to categorize geochemical processes in surficial aquifers. Here, we describe the application of a commercially available gas vapor sampling probe to ground water sampling in shallow coastal aquifers. The system involves a small‐diameter, shielded‐screen well‐point sampler that can provide high resolution (∼10 cm) to depths of 10 m or greater depending on the aquifer matrix. Examples of the system’s utility are presented for two geologically contrasting environments (Waquoit Bay, Massachusetts, USA; Ubatuba, Brazil). In Waquoit Bay, the sampler allowed us to resolve a sharp saline transition zone (∼2 m) and the associated changes in nutrients and trace metals that were associated with biogeochemical reactions at this interface. The system also proved useful in Ubatuba, Brazil, where small‐scale gradients in sediment composition and permeability controlled the ground water salinity profile.