A portable underway flow‐through sampler for rapid survey of contaminated river plumes in coastal waters

Abstract

AbstractLand‐sourced contaminants conveyed by rivers, particularly during flood flows, are a major source of coastal water degradation. Typically, muddy and contaminated river flood plumes are episodic and transient and therefore difficult to survey and sample. We developed a Portable Underway Flow‐Through Sampler for rapid response and survey of river flood events (PUFTS‐rapid). The sampler is highly portable, compact, quick to setup, and easy to use in small boats, for spatial mapping of surface waters during fast transects (up to 25 knots). Key components of the system include: a 12 V self‐priming pump that pulls in ambient surface water; a vortex unit to remove air bubbles, and a water quality sonde operated with a flow‐cell attachment. Sonde sensors include conductivity (salinity), temperature, turbidity, and fluorescence of dissolved organic matter. GPS position is logged, together with water quality data, by the sonde hand‐held unit. Water samples are obtained periodically from the continuous flow—for laboratory calibration and validation of sonde sensors as well as discrete analyses of contaminants. We illustrate sampler capability with survey of a muddy, contaminated flood plume from the Hutt River dispersing into Wellington Harbor, New Zealand. Although capture of turbid plumes from river floods is probably the most demanding application of PUFTS‐rapid, the sampler is expected to be valuable more broadly for coastal water quality applications, including survey of plumes from port dredging, “sea‐truthing” of remote sensing imagery, and calibration and validation of hydrodynamic models.