Pore water sampling in acid sulfate soils: a new peeper method

This study describes the design, deployment, and application of a modified equilibration dialysis device (peeper) optimized for sampling pore waters in acid sulfate soils (ASS). The modified design overcomes the limitations of traditional-style peepers, when sampling firm ASS materials over relatively large depth intervals. The new peeper device uses removable, individual cells of 25 mL volume housed in a 1.5 m long rigid, high-density polyethylene rod. The rigid housing structure allows the device to be inserted directly into relatively firm soils without requiring a supporting frame. The use of removable cells eliminates the need for a large glove-box after peeper retrieval, thus simplifying physical handling. Removable cells are easily maintained in an inert atmosphere during sample processing and the 25-mL sample volume is sufficient for undertaking multiple analyses. A field evaluation of equilibration times indicates that 32 to 38 d of deployment was necessary. Overall, the modified method is simple and effective and well suited to acquisition and processing of redox-sensitive pore water profiles>1 m deep in acid sulfate soil or any other firm wetland soils.