High-frequency, long-duration water sampling in acid mine drainage studies: A short review of current methods and recent advances in automated water samplers

•Review of difficulties and limitations of traditional hand-collected water sampling.•Review of currently available automated water samplers.•Discussion of newly developed automated water samplers.•Application of high-frequency, long-duration water sampling to acid mine drainage studies.

Hand-collected grab samples are the most common water sampling method but using grab sampling to monitor temporally variable aquatic processes such as diel metal cycling or episodic events is rarely feasible or cost-effective. Currently available automated water samplers are a proven, widely used technology and typically collect as many as 24 samples during a deployment. However, these automated water samplers are not well suited for long-term sampling in remote areas or in freezing conditions. There is a critical need for low-cost, long-duration, high-frequency water sampling technology to improve our understanding of the geochemical response to temporally variable processes. This review article will examine recent developments in automated water sampler technology and utilize selected field data from acid mine drainage studies to illustrate the utility of high-frequency, long-duration water sampling.