Measuring trace contaminants in water is a challenging task. By definition, trace contaminants appear in very low concentrations. Accurate measurements require collection and filtration of large volumes of water with suspended particles (sediment) in order to collect enough material for analysis. The...
In the Beginning… In the 1960’s oceanographers started suggesting that sinking particles were a main source of food and nutrient delivery to deep-sea organisms. Researchers soon conceived and deployed sediment traps to investigate further (Wiebe et al., 1976). They quickly realized that the sediment...
Understanding particle behavior in the aquatic environment is fundamental to unraveling key processes in biogeochemistry, sediment transport, and ecosystem dynamics. Since 1995, Sequoia’s LISST and Hyper instruments have become important tools for quantifying particle size distributions (PSDs), concentrations...
In the remote, frigid and – often – ice-covered waters of the Arctic Ocean and the Southern Ocean, complex interactions between physical, chemical, and biological processes shape global climate and marine ecosystems. Scientists use a comprehensive range of sensors, platforms, vehicles and methodologies...
Light scattering in the ocean is described by the Volume Scattering Function (VSF). This is an Inherent Optical Property (IOP) characterizing how light is scattered at different angles in water. For oceanographers, in situ measurements of the VSF are essential for decoding the underwater light field...
When designing a transmissometer or a laser diffraction-based sensor for particle size analysis, an important consideration is the beam acceptance angle. A transmissometer measures a—generally small—portion of the forward-scattered light: light that scatters away from the beam but remains within...
In the underwater world, visibility is everything. Whether it’s a diver navigating murky waters, an autonomous vehicle scanning the seafloor, or a naval operation relying on optical sensors, understanding how light behaves underwater is critical. The beam attenuation coefficient (c) provides a...
As cities grow and landscapes transform, the effects of urbanization ripple far beyond skylines and traffic patterns. An often overlooked consequence is the increase in suspended sediment concentration in nearby rivers, lakes, and coastal waters. This can have massive implications for water quality,...
Understanding the composition of suspended particles in the ocean is essential for unraveling biogeochemical cycles, assessing ecosystem health, and improving remote sensing algorithms. Among the suite of optical tools available to oceanographers, in situ hyperspectral backscattering measurements such...
In aquatic optics and phytoplankton ecology, chlorophyll-a has long been the go-to proxy for estimating biomass and productivity. However, as our understanding of aquatic ecosystems deepens, so does our need for more nuanced tools. One such tool is Sequoia’s hyperspectral absorption meter, the...