Estimating the Underwater Diffuse Attenuation Coefficient with a Low-Cost Instrument: The KdUINO DIY Buoy

Abstract

A critical parameter to assess the environmental status of water bodies is the transparency of the water, as it is strongly affected by different water quality related components (such as the presence of phytoplankton, organic matter and sediment concentrations). One parameter to assess the water transparency is the diffuse attenuation coefficient. However, the number of subsurface irradiance measurements obtained with conventional instrumentation is relatively low, due to instrument costs and the logistic requirements to provide regular and autonomous observations. In recent years, the citizen science concept has increased the number of environmental observations, both in time and space. The recent technological advances in embedded systems and sensors also enable volunteers (citizens) to create their own devices (known as Do-It-Yourself or DIY technologies). In this paper, a DIY instrument to measure irradiance at different depths and automatically calculate the diffuse attenuation Kd coefficient is presented. The instrument, named KdUINO, is based on an encapsulated low-cost photonic sensor and Arduino (an open-hardware platform for the data acquisition). The whole instrument has been successfully operated and the data validated comparing the KdUINO measurements with the commercial instruments. Workshops have been organized with high school students to validate its feasibility.

Expanding Aquatic Observations through Recreation

“…With a push toward environmental sensors becoming smaller and cheaper, there is scope to expand the range of environmental indicators that could be measured, for instance, phytoplankton fluorescence (Leeuw et al, 2013;Zeng and Li, 2015), light attenuation (Bardaji et al, 2016), water color (Busch et al, 2016a), pH and oxygen (Larsen et al, 2011). Sensor developments for monitoring nutrient concentrations (Beaton et al, 2011) and toxic pollutants (Lafleur et al, 2010) may one day be feasible from such platforms.…”

Citizen Bio-Optical Observations from Coast- and Ocean and Their Compatibility with Ocean Colour Satellite Measurements

“…for Secchi depth is semi-empirical [10], it is clear that this product makes the simplest direct coupling with citizen observations. Water transparency measurements with the KdUINO are received with a smartphone app, which includes a calibration of the different light collectors towards the strongest signal reached in the measurement [28]. The KdUINO measures the attenuation of diffuse downwelling radiation over a large wavelength range that is not exactly identical to PAR.…”

“…(1) The smartphone app EyeOnWater-Colour to measure water colour [25,26], based on the well described Forel-Ule colour comparator scale [27], (2) The KdUINO, which is an underwater buoy-based light chain to measure the attenuation of light throughout the water column [28], (3) The TrandiCam (TRANsparency unDerwater Index based on Citizen cAMera pictures) to assess underwater visibility as a measure of water transparency through underwater photographs [29], (4) And the SmartFluo as a novel smartphone based fluorometer to measure algal biomass by proxy…”

“…KdUINO is made as a Do-It-Yourself (DIY) kit with open hardware, firmware, and software (hermetic bottle of approx. 25 × 15 cm and light collector chain of variable length, 50 €) [28]. Its main components are a set of four to six encapsulated low-cost photonic sensors and an Arduino board (an open hardware platform) as interface electronics, with a real-time clock for data acquisition.…”

“…Its main components are a set of four to six encapsulated low-cost photonic sensors and an Arduino board (an open hardware platform) as interface electronics, with a real-time clock for data acquisition. The instrument was completed with a mobile application which allows for the collection of KdUINO data remotely [28]. When a connection is available, the data are sent to a server.…”