Bio-optical anomalies in the world’s oceans: An investigation on the diffuse attenuation coefficients for downward irradiance derived from Biogeochemical Argo float measurements

Identification of oceanic regions characterized by particular optical properties is extremely important for ocean color applications. The departure from globally established bio-optical models (i.e., anomaly) introduces uncertainties in the retrieval of biogeochemical quantities from satellite observations. Thanks to an array of 105 Biogeochemical Argo floats acquiring almost daily downward irradiance measurements at selected wavelengths in the UV and blue region of the spectrum, we reexamined the natural variability of the spectral diffuse attenuation coefficients, Kd(λ), among the world’s oceans and compared them to previously established bio-optical models. The analysis of 2847 measurements of Kd(λ) at 380 and 490 nm, within the first optical depth, provided a classification of the examined regions into three groups. The first one included the Black Sea, a water body characterized by a very high content of coloured dissolved organic matter (CDOM). The second group was essentially composed by the subtropical gyres (Atlantic and Pacific Oceans), with optical properties consistent with previous models (i.e., no anomalies). High latitude (North Atlantic and Southern oceans) and temperate (Mediterranean Sea) seas formed the third group, in which optical properties departed from existing bio-optical models. Annual climatologies of the Kd(380)/Kd(490) ratio evidenced a persistent anomaly in the Mediterranean Sea, that we attributed to a higher-than-average CDOM contribution to total light absorption. In the North Atlantic subpolar gyre, anomalies were observed only in wintertime and were also attributed to high CDOM concentrations. In the Southern Ocean, the anomaly was likely related to high phytoplankton pigment packaging rather than to CDOM

Hair resistance to mechanical wear

Hair mechanical properties are primary indicators of hair integrity. Here we describe a methodology based on hair's resistance to mechanical wear to evaluate cosmetic treatments. Using a vibrational vortex cycle, we developed a protocol that relies on the plastic deformation and degradation of hair, due to frictional forces between hardened steel balls and hair fragments. We demonstrate that the balls when in contact with the hair fragments promoted extended hair degradation. The degree of degradation was related to hair's resistance to mechanical wear. Lower degradation rates reflect high resistance to mechanical wear. We found differences according to hair ethnicity and type of treatment. This methodology shows great potential for the screening and evaluation of the effect of cosmetic treatments on hair.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit and BioTecNorte operation (NORTE-01-0145-FEDER000004) funded by the European Regional Development Fund under the scope of Norte 2020 - Programa Operacional Regional do Norte. AT thanks FTC for funding the scholarship with the reference SFRH/BD/114035/2015.info:eu-repo/semantics/publishedVersio

SIGNIFICANCE OF COLLOIDS IN THE BIOGEOCHEMICAL CYCLING OF ORGANIC-CARBON AND TRACE-METALS IN THE VENICE LAGOON (ITALY)

Colloidal organic C and trace metals from the waters df a highly productive coastal environment (the Venice Lagoon, Italy) have been separated by a cross-flow ultrafiltration device. On average, 18% of organic C, 34% of Cd, 46% of Cu, 87% of Fe, 18% of Ni, 58% of Pb, and 54% of Mn which previously would have been considered in the dissolved phase are actually associated with colloidal material, Thus, past studies overestimate the dissolved trace-metal concentration in the nearshore environment. Compared to total concentration, the proportion of the colloidal fraction represents on average 15% of organic C, 18% of Cd, 28% of Cu, 11% of Fe, 11% of Ni, 29% of Pb, and 12% of Mn. This fraction acts differently from the truly dissolved and macroparticulate phases. The behavior of organic C and trace elements during mixing between freshwater and seawater is more complicated than expected when a colloidal fraction is involved. The flocculation of colloids, encountered normally during estuarine mixing, is not very significant on the time scale of mixing in the lagoon. Conversely, the interaction between colloidal and truly dissolved phases seems important. The partitioning of trace metals between different fractions of organic C appears variable, Fe and Mn are preferentially tied to macroparticulate organic matter, and Cu and Cd are preferentially tied to colloidal organic matter in seawater. Truly dissolved organic C appears to be important for Ni. Pb is mainly associated with microparticulate organic matter at most stations except in the highly productive region where Pb prefers colloidal organic C

THE SIGNIFICANT ROLE OF COLLOIDS IN THE TRANSPORT AND TRANSFORMATION OF ORGANIC-CARBON AND ASSOCIATED TRACE-METALS (CD, CU AND NI) IN THE RHONE DELTA (FRANCE)

The distribution of organic C and trace elements (Cd, Cu, and Ni) between truly dissolved and colloidal phases was determined in May 1992, in order to better understand their behavior during estuarine mixing in the Rhone delta (France). Colloidal material (10(4) Daltons-0.4 mu m) was separated with an ultra-clean cross-flow filtration system. A considerable part of the organic C and trace metals studied, used to be considered to occur in the so-called ''dissolved'' pool, is associated with colloidal material. The significant correlation between colloidal organic C and colloidal Cu suggests an important involvement of colloidal organic material in the transport of this element. The correlation between Ni, Cd and organic matter mainly occurs in the truly dissolved fraction, suggesting that the truly dissolved organic C is important for these two elements. Truly dissolved and colloidal organic C and trace-metal fluxes transported from the River Rhone to the northwestern Mediterranean Sea were estimated