Optical variability of seawater in relation to particle concentration, composition, and size distribution in the nearshore marine environment at Imperial Beach, California

Abstract

[1] We examined optical variability of seawater in relation to particle concentration, composition, and size distribution in the nearshore marine environment at Imperial Beach, California, over a period of 1.5 years. Measurements included the hyperspectral inherent optical properties (IOPs) of seawater (particulate beam attenuation, particulate and CDOM absorption coefficients within the spectral range 300-850 nm), particle size distribution (PSD) within the diameter range 2-60 mm, and the mass concentrations of suspended particulate matter (SPM), particulate organic carbon (POC), and chlorophyll a (Chl). The particulate assemblage spanned a wide range of concentrations and composition, from the dominance of mineral particles (POC/SPM < 0.06) with relatively steep PSDs to the high significance or dominance of organic particles (POC/SPM > 0.25) with considerably greater contribution of larger-sized particles. Large variability in the particulate characteristics produced correspondingly large variability in the IOPs; up to 100-fold variation in particulate absorption and scattering coefficients and several-fold variation in the SPM-specific and POC-specific coefficients. Analysis of these data demonstrates that knowledge of general characteristics about the particulate composition and size distribution leads to improved interpretations of the observed optical variability. We illustrate a multistep empirical approach for estimating proxies of particle concentration (SPM and POC), composition (POC/SPM), and size distribution (median diameter) from the measured IOPs in a complex coastal environment. The initial step provides information about a proxy for particle composition; other particulate characteristics are subsequently derived from relationships specific to different categories of particulate composition. Cieplak (2010), Optical variability of seawater in relation to particle concentration, composition, and size distribution in the nearshore marine environment at

Shellfish Aquaculture from Space: Potential of Sentinel2 to Monitor Tide-Driven Changes in Turbidity, Chlorophyll Concentration and Oyster Physiological Response at the Scale of an Oyster Farm

“…Enhanced characterization of the composition of the particulate assemblage could also be used to improve satellite-derived aquaculture products. For example, as oysters have the ability to preferentially select organic rather than mineral particles before ingestion Dutertre et al, 2009), estimation of the organic fraction of the particulate assemblage (Woźniak et al, 2010) could be used to better constrain shellfish physiological models.…”

Estimating Suspended Sediment Concentration in Streams by Diffuse Light Attenuation

“…Water settings that have received the most K d research include estuaries and continental shelf, which are optically complex due to large variability in concentration and composition of the particulate and dissolved organic matter (Wozniak et al 2010). Less published work is available which relates light attenuation to sediment transport in streams, but it is recognized that streams are typically less optically complex due to low hydraulic retention time that reduces suspended biologic activity (Vannote et al 1980;Davies-Colley and Nagels 2008;Julian et al 2008a).…”

Patterns of suspended particulate matter across the continental margin in the Canadian Beaufort Sea

“…The proportion of organic to inorganic material is important because mineral particles have typically higher refractive index compared to organic particles, and thus generally produce higher scattering (e.g., Babin et al, 2003b;Woźniak et al, 2010). Beam attenuation is also affected by variable absorption.…”

“…bution of particle assemblages (Kitchen et al, 1982;Bunt et al, 1999;Babin et al, 2003b;Reynolds et al, 2010;Woźniak et al, 2010;Hill et al, 2011), and may thus show regional differences. The proportion of organic to inorganic material is important because mineral particles have typically higher refractive index compared to organic particles, and thus generally produce higher scattering (e.g., Babin et al, 2003b;Woźniak et al, 2010).…”

“…Following Woźniak et al (2010), the data representing discrete seawater samples were partitioned into three compositionrelated groups based on the POC/SPM ratio: 1) mineral-dominated when POC/SPM < 0.06, 2) mixed when 0.06 leq POC/SPM leq 0.25, and 3) organic-dominated when POC/SPM > 0.25. Only on station 394 (13 m bottom depth) near the entrance to Kugmallit Bay did the CTD/Rosette sampling from the CCGS Amundsen take place sufficiently close to the coast to reach the mineral-dominated water masses.…”