Quantitative and qualitative characterizations of dissolved organic matter (DOM) were carried out at the watershed level in central Japan by measuring dissolved organic carbon (DOC) concentration and the three-dimensional excitation-emission matrix (3-D EEM). DOC concentration was low (mean 37 ± 19 mM C) in the upstream waters, whereas, in general, it increased toward the downstream areas (mean 92 ± 47 mM C). Significant variations in DOC concentration were detected among rivers and channels. DOC concentration in the epilimnion of Lake Biwa increased during the summer period and decreased during the winter period. The lake hypolimnion has lower DOC concentration (mean 87 ± 7 mM C) compared with the epilimnion (107 ± 15 mM C). Fulvic acid (FA)-like substances in the DOM were directly characterized by 3-D EEM. The fluorescence peak for upstream DOM was found in regions with longer wavelengths (excitation/emission 386 ± 6/476 ± 5 nm) compared with downstream and lake DOM (351 ± 12/ 446 ± 15 nm and 341 ± 6/434 ± 6 nm, respectively). The DOC concentration is correlated with fluorescence peak intensity of FA-like substances in DOM in river waters. Such a relationship was not found in lake DOM. A blueshift of the fluorescence peak from upstream to lake DOM was observed. A decrease in fluorescence intensities was also detected during the summer period. These results may suggest that the degradation of FA-like substances in DOM occurs from natural solar irradiation. Protein-like fluorescence was significantly detected in the lake epilimnion during the summer period. A linear relationship between DOC concentration and protein-like fluorescence indicated that an autochthonous input of DOM gave rise to the increase in DOC concentration in the lake epilimnion during the summer. These results may suggest that the 3-D EEM can be used as a tool for the investigation of DOM dynamics at the watershed level with concurrent measurement of DOC concentration and the fluorescence properties of fulvic acidlike and protein-like substances.

No abstract

MATHEMATICAL MODELA computerized method was developed for simulating transient state heat and moisture transfer and stress distribution in axisymmetric food undergoing drying process. For this development, a simultaneous heat and moisture transfer model was coupled with the virtual work principle applicable to a body undergoing volumetric changes. The developed method was verified by comparing experimental results with those predicted. Experimental results were obtained by drying cylindrically formed samples of hydrated starch granules. They included central temperature, average concentration histories and photographically observed internal crack formations.Heat and moisture transfer Governing equations for heat and moisture transfer were obtained by modifying Luikov's model (Hayakawa and Puruta, 1989). An equation for transient state moisture transfer in food is:(1) where the first term on the right-hand-side (RI-IS) represents the change of moisture flux, the second term the rate of moisture generation (nr = 2) or loss (n, = 1) due to chemical reactions and the third term the internal rate of moisture vaporization or condensation. The total moisture flux, J,, consists of the following three terms: i. flux due to a moisture concentration gradient (diffusional flux), ii. flux due to a temperature gradient (Soret flux), and iii. flux due to a pressure gradient (filtrational flux), Eq. (2).

The dynamics of fluorescent dissolved organic matter (FDOM) in the large monomictic freshwater Lake Biwa (surface area 675 km 2 , maximum depth 104 m) was studied from December 2010 to December 2011. The proteinlike FDOM (FDOM T ) and dissolved organic carbon (DOC) showed epilimnetic accumulation (FDOM T from 4.42 6 0.22 quinine sulfate units [QSU] to 6.30 6 0.04 QSU; DOC from 80.8 6 2.7 mmol L 21 to 102.7 6 3.5 mmol L 21 ) between nutrient-replete winter mixing to nutrient-depleted stratified periods. This accumulation is attributed to the reduced heterotrophic activity following severe P-limitation. The positive correlation between accumulated DOC and FDOM T in the epilimnion and their uniform reduction in the hypolimnion (, 9%) suggest FDOM T as a proxy for semi-labile DOM. The humic-like FDOM (FDOM M ) generally increased with depth, a pattern similar to nutrients and total carbon dioxide (TCO 2 ), but adverse to dissolved oxygen. The significant positive correlations of FDOM M with apparent oxygen utilization (r 5 0.86, p , 0.001), TCO 2 (r 5 0.91, p , 0.001), nitrate (r 5 0.83, p , 0.001), and phosphate (r 5 0.76, p , 0.001) in the deeper layers suggest that FDOM M is formed during hypolimnetic mineralization. We estimated that , 8% of the organic carbon degraded in the hypolimnion is transferred into humic substances. The minor contribution of DOC (6.4%) to hypolimnetic mineralization suggests that production of humic substances is mainly fueled by the mineralization of sinking biogenic particles. The production and consumption of FDOM in freshwater lakes may influence the quality and bioavailability of carbon exported from these systems.

Abstract. Ocean acidification, a complex phenomenon that lowers seawater pH, is the net outcome of several contributions. They include the dissolution of increasing atmospheric CO2 that adds up with dissolved inorganic carbon (dissolved CO2, H2CO3, HCO3−, and CO32−) generated upon mineralization of primary producers (PP) and dissolved organic matter (DOM). The aquatic processes leading to inorganic carbon are substantially affected by increased DOM and nutrients via terrestrial runoff, acidic rainfall, increased PP and algal blooms, nitrification, denitrification, sulfate reduction, global warming (GW), and by atmospheric CO2 itself through enhanced photosynthesis. They are consecutively associated with enhanced ocean acidification, hypoxia in acidified deeper seawater, pathogens, algal toxins, oxidative stress by reactive oxygen species, and thermal stress caused by longer stratification periods as an effect of GW. We discuss the mechanistic insights into the aforementioned processes and pH changes, with particular focus on processes taking place with different time scales (including the diurnal one) in surface and subsurface seawater. This review also discusses these collective influences to assess their potential detrimental effects to marine organisms, and of ecosystem processes and services. Our review of the effects operating in synergy with ocean acidification will provide a broad insight into the potential impact of acidification itself on biological processes. The foreseen danger to marine organisms by acidification is in fact expected to be amplified by several concurrent and interacting phenomena.

No abstract

A COMPUTERIZED MODEL for the prediction of thermal responses and lethality of packaged particles-liquid food was developed by assuming a statistical particle volume distribution for spherical, cylindrical, oblate spheroidal-shaped particles. For the model development, an overall heat balance equation was solved in combination with an equation for transient heat conduction. To solve the latter, Duhamel's theorem and empirical formulae containing f-and j-values were used. The reliability of the model was verified experimentally by processing canned potatoes-in-brine in an agitated cooker.

Abstract. Ocean acidification, a complex phenomenon that lowers seawater pH, is the net outcome of several contributions. They include the dissolution of increasing atmospheric CO2 that adds up with dissolved inorganic carbon (dissolved CO2, H2CO3, HCO3−, and CO32−) generated upon mineralization of primary producers (PP) and dissolved organic matter (DOM). The aquatic processes leading to inorganic carbon are substantially affected by increased DOM and nutrients via terrestrial runoff, acidic rainfall, increased PP and algal blooms, nitrification, denitrification, sulfate reduction, global warming (GW), and by atmospheric CO2 itself through enhanced photosynthesis. They are consecutively associated with enhanced ocean acidification, hypoxia in acidified deeper seawater, pathogens, algal toxins, oxidative stress by reactive oxygen species, and thermal stress caused by longer stratification periods as an effect of GW. We discuss the mechanistic insights into the aforementioned processes and pH changes, with particular focus on processes taking place with different timescales (including the diurnal one) in surface and subsurface seawater. This review also discusses these collective influences to assess their potential detrimental effects to marine organisms, and of ecosystem processes and services. Our review of the effects operating in synergy with ocean acidification will provide a broad insight into the potential impact of acidification itself on biological processes. The foreseen danger to marine organisms by acidification is in fact expected to be amplified by several concurrent and interacting phenomena.