Compositional differences of fluorescence dissolved organic matter in Arctic Ocean drift sea ice and surface waters north of Svalbard in spring.

We assessed the qualitative composition of fluorescent dissolved organic matter (FDOM) in Arctic Ocean surface water and in sea ice north of the Svalbard Archipelago (in the Sophia Basin, the Yermak Plateau and the north Spitsbergen shelf) in May and June 2015, during the “TRANSSIZ” expedition (Transitions in the Arctic Seasonal Sea Ice Zone). Samples collected in open lead waters (OW), under-ice waters (UIW) and from the sea ice (ICE) were analyzed by fluorescence spectroscopy and subsequently by multivariate statistical methods using Parallel Factor Analysis (PARAFAC). Statistical analyses of all measured DOM fluorescence excitation and emission matrices (EEMs) enabled four components to be identified and validated. The spectral characteristics of the first component C1 (λEx/λEm 282(270)/335) corresponded to those of tryptophan. The spectral properties of the other three components corresponded to those of humic-like substances: components two (C2 − λEx/λEm 315(252)/395) and three (C3 − λEx/λEm 357(258)/446) corresponded to humic-like substances of marine origin, whereas component four (C4 − λEx/λEm 261(399)/492) resembled terrestrial humic-like substances. Changes in FDOM composition were recorded in OW, in contrast to UIW and sea ice. In the OW the sum of fluorescence intensities of humic-like components (C2, C3 and C4) was two times higher than the fluorescence intensity of protein-like component (C1). Component C2 exhibited the highest fluorescence intensity. In the UIW and particularly in the sea ice the fluorescence intensity of the protein-like component, IC1, was the highest. The IC1 in the sea ice increased toward the sea ice bottom, reaching maximum values at the sea ice-water interface. The calculated spectral indices (SUVA(254) and HIX) and ratios of fluorescence intensities of protein-like to humic-like components, Ip/Ih, suggested that FDOM in water and sea ice was predominantly autochthonous, characterized by low molecular weight organic compounds and low aromatic ring saturation. Enrichment factors Dc, calculated from salinity-normalized values of the optical DOM properties and dissolved organic carbon concentrations, indicated the significant fractionation of FDOM in the sea ice relative to the parent open waters. The humic-like terrestrial component C4 was enriched the least, whereas the protein-like component C1 was enriched the most. A statistically significant (p < 0.0001) and relatively strong (R = 63) correlation between IC1 and the total chlorophyll a concentration Tchla was found in the sea ice, which suggests that sympagic algal communities were producers of the protein-like FDOM fraction

Inherent optical properties and remote sensing reflectance of Pomeranian lakes (Poland)**This paper was carried out within the framework of the SatBałtyk project funded by the European Union through European Regional Development Fund (contract No. POIG.01.01.02-22-011/09 entitled ‘The Satellite Monitoring of the Baltic Sea Environment’). The partial support for this study was also provided by the MNiSW (Ministry of Science Higher Education) as a research project N N306 066434 in the years 2008–2011 also as a part of Pomeranian University IO PAS’s statutory research.The results published in this paper were presented at the international conference Ocean Optics XXI, Glasgow, Scotland, 8–12 October 2012.

AbstractThis paper describes the results of comprehensive empirical studies of the inherent optical properties (IOPs), the remote sensing reflectance Rrs(λ) and the contents of the principal optically active components (OAC) i.e. coloured dissolved organic matter (CDOM), suspended particulate matter (SPM) and chlorophyll a, in the waters of 15 lakes in Polish Pomerania in 2007–2010. It presents numerous spectra of the total absorption a(λ) and scattering b(λ)≈bp(λ) of light in the visible band (400–700nm) for surface waters, and separately, spectra of absorption by CDOM aCDOM(λ) and spectra of the mass-specific coefficients of absorption a*(SPM)p(λ) and scattering b*(SPM)p(λ) by SPM. The properties of these lake waters are highly diverse, but all of them can be classified as Case 2 waters (according to the optical classification by Morel & Prieur 1977) and they all have a relatively high OAC content. The lakes were conventionally divided into three types: Type I lakes have the lowest OAC concentrations (chlorophyll concentration Ca=(8.76±7.4) mg m−3 and CDOM absorption coefficients aCDOM(440)=(0.57±0.22) m−1 (i.e. mean and standard deviation), and optical properties (including spectra of Rrs(λ)) resembling those of Baltic waters. Type II waters have exceptionally high contents of CDOM (aCDOM(440)=(15.37±1.54) m−1), and hence appear brown in daylight and have very low reflectances Rrs(λ) (of the order of 0.001sr−1). Type III waters are highly eutrophic and contain large amounts of suspended matter, including phytoplankton (CSPM=(47.0±39.4) g m−3, Ca=(86.6±61.5) mg m−3; aCDOM(440)=(2.77±0.86) m−1). Hence the reflectances Rrs(λ) of these type of waters are on average one order of magnitude higher than those of the other natural waters, reaching maximum values of 0.03sr−1 in λ bands 560–580nm and 690–720nm (see Ficek et al. 2011). The article provides a number of empirical formulas approximating the relationships between the properties of these lake waters

Physicochemical characterization and dissolution studies of solid dispersions of clotrimazole with chitosan

The aim of the present study was to increase the solubility of clotrimazole. Among the methods to increase the solubility selected solid dispersions of the drug with the polymer. Chitosan was used as the polymer. Clotrimazole was incorporated into the chitosan type 652 with molar masse chitosan Mη = 429 kDa. Solid dispersions were prepared by using different ratios of clotrimazole and chitosan (1:9, 3:7, 5:5, 7:3, 9:1). Formulations were tested dissolution rate of the drug. The highest dissolution of clotrimazole, amounting to 47.95%, was observed after 60 minutes from solid dispersion prepared by grinding method and 42.84% from physical mixtures with drug-polymer weight ratio 1:9 in the presence chitosan. The solubility of the drug improved more than 37-fold. XRPD analysis indicates the presence of the clotrimazole in crystalline form in the solid dispersion obtained by kneading method

Empirical Relationships between Remote-Sensing Reflectance and Selected Inherent Optical Properties in Nordic Sea Surface Waters for the MODIS and OLCI Ocean Colour Sensors

The Nordic Seas and the Fram Strait regions are a melting pot of a number of water masses characterized by distinct optical water properties. The warm Atlantic Waters transported from the south and the Arctic Waters from the north, combined with the melt waters contributing to the Polar Waters, mediate the dynamic changes of the year-to-year large-scale circulation patterns in the area, which often form complex frontal zones. In the last decade, moreover, a significant shift in phytoplankton phenology in the area has been observed, with a certain northward expansion of temperate phytoplankton communities into the Arctic Ocean which could lead to a deterioration in the performance of remote sensing algorithms. In this research, we exploited the capability of the satellite sensors to monitor those inter-annual changes at basin scales. We propose locally adjusted algorithms for retrieving chlorophyll a concentrations Chla, absorption by particles ap at 443 and 670 nm, and total absorption atot at 443 and 670 nm developed on the basis of intensive field work conducted in 2013&ndash;2015. Measured in situ hyper spectral remote sensing reflectance has been used to reconstruct the MODIS and OLCI spectral channels for which the proposed algorithms have been adapted. We obtained MNB &le; 0.5% for ap(670) and &le;3% for atot(670) and Chla. RMS was &le;30% for most of the retrieved optical water properties except ap(443) and Chla. The mean monthly mosaics of ap(443) computed on the basis of the proposed algorithm were used for reconstructing the spatial and temporal changes of the phytoplankton biomass in 2013&ndash;2015. The results corresponded very well with in situ measurements