Particulate organic carbon and nitrogen in the adjacent seas of the Pacific Ocean

Particulate organic carbon (POC) and nitrogen in sea water were measured in samples collected in the adjacent seas of the Pacific Ocean during the cruises of T. S. Oshoro-Maru (1969, 1970) and the R. V. Hakuho-Maru (KH-70-4, KH-72-1). High values were obtained in the northern North Pacific and the Bering Sea, the concentration of particulate carbon in the upper 50-m layer ranged from 35 to 550 g Cl^-1. In the deep waters of these area, values above 50 g Cl^-1 were frequently observed. The lowest values in the surface layer and deeper layers were obtained in the Japan Sea (23 gCl^-1) and in the South China Sea (7 g Cl^-1) respectively. A consistent minimum was located in the intermediate waters (100–400 m) throughout the entire region studied. Variation with depth was generally irregular with marked peak values in different layers. The POC distribution consited of these peak values and a relatively uniform background concentration. These background values slightly decreased with increasing depth and were different locally. Correlation analysis between carbon concentration and apparent oxygen utilization (AOU) of ambient water for the samples in the Japan Sea and the Sulu Sea showed that there was no systematic decrease of particulate carbon with increasing AOU. In these areas, the carbon concentration scattered in the higher AOU domain ranged from 10–100 g Cl^-1. These observations support the conception that downward transport of particulate matter from the overlying surface layer in the adjacent seas of the Pacific Ocean may be fairly rapid.     

Obligate commensalism of <Emphasis Type="Italic">Curvemysella paula</Emphasis> (Bivalvia: Galeommatidae) with hermit crabs

Curvemysella paula is a markedly crescent-shaped bivalve that lives inside snail shells occupied by hermit crabs. Here, we describe the unique symbiotic life, growth pattern, and reproductive biology of this bivalve, based on specimens collected from the shallow, muddy bottom of the Seto Inland Sea, Japan. C. paula was found attached to columellae in the siphonal canal, mainly of nassariid snail shells occupied by two types of hermit crabs: Diogenes edwardsii (Diogenidae) and Spiropagurus spiriger (Paguridae). The crescent-shaped shell of C. paula is an adaptation to symbiotic life in the narrow interspace between the snail shell and the hermit-crab abdomen. C. paula is a protandric hermaphrodite. In our samples, each host snail shell harbored one (or rarely a few) large female and several males. All the female bivalves settled on the host shells with their anterior end facing outward and benefited from currents created by the hermit crab when feeding. In the muddy bottom, snail shells are a limited resource for both the hermit crabs and symbiotic bivalves. The bivalves benefit from the mobility of the hermit crabs, which prevent the shells from becoming buried in the mud. C. paula represents the only example of obligate commensalism with hermit crabs found in Bivalvia.     

Particulate organic carbon and nitrogen in the eastern pacific ocean

Particulate organic carbon and nitrogen in sea water were measured in samples collected along a line 155°W; 50° N-15°S, during the cruise of R.V. “Hakuho-Maru” (KH-69-4). High concentrations of particulate matter were generally found at or near the sea surface; the concentrations decreased rapidly with depth. A consistent minimum was located in the depth range 150 to 250 m through the entire section sampled. The subsurface maximum layers roughly coincided with the chlorophyll maximum, but several irrregularities were noted. One of the most remarkable features of the vast stratum below 200 m depth was the presence of distinctively regional variation in concentration of particulate material through the entire section. In the section, we could define at least 6 large water parcels, vertically oriented, all with significantly different concentrations of both carbon and nitrogen. Variation in the deep water ranged from less than 5 μgC/l to more than 50 μgC/l. Correlation analysis between carbon concentration and apparent oxygen utilization (AOU) of ambient water for all samples showed that the carbon from particle-poor water parcels consistently decreased with increasing AOU, levelling to a practically constant low of around 5 to 10 μgC/l, whereas the carbon from particle-rich parcels was anomalously high (10 to 50 μgC/l) in the range of high AOU, and showed no consistent trend of convergence. The intergrated amount of particulate carbon in the total water column at each station was in the range 20 to 150 gC/m². More than 90% of this total amount was in the water column below 200 m depth, and the correlation of total amount of particulate material between the surface layer (0 to 200 m) and the water column below 200 m depth was highly significant. These observations are considered to indicate that the downward transport of these materials may be much quicker than so far estimated, at least in some localized areas.     

Update of daily intake of PCDDs, PCDFs, and dioxin-like PCBs from food in Japan

Total diet study (TDS) samples of 14 food groups from 16 locations in Japan, collected in 1999 and 2000, were analyzed for polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (dioxin-like PCBs) to estimate the update of daily intake of these contaminants from food. The mean daily intake of toxic equivalency (TEQ) for an adult weighing 50 kg, calculated at non-detected isomer concentrations equal to zero (ND=0), was estimated to be 2.25 pg TEQ/kg b.w./day. When non-detected isomer concentrations are assumed to be equal to half of the limits of detection (ND=1/2 LOD), the mean daily intake was estimated to be 3.22 pg TEQ/kg b.w./day. These values were below the tolerable daily intake (TDI) of 4 pg TEQ/kg b.w. for PCDD/Fs and dioxin-like PCBs set in Japan. In both the estimates, the mean daily intakes were highest from fish and shellfish (76.9% at ND=0 and 53.9% at ND=1/2 LOD of the total TEQs), followed by those from meat and eggs (15.5% at ND=0 and 11.7% at ND=1/2 LOD of the total TEQs). Congener specific data revealed that these total TEQ levels were dominated by 1,2,3,7,8-PeCDD, 2,3,4,7,8-PeCDF and 3,3^′,4,4^′,5-PeCB in each case (71.7% at ND=0 and 63.1% at ND=1/2 LOD of the total TEQs). The dioxin-like PCBs (non-ortho and mono-ortho PCBs) accounted for about 50% of these total TEQs. These data will be very useful in the risk assessment of PCDD/Fs and dioxin-like PCBs from food in Japan.     

Development of an environmentally acceptable volatile organic compounds recovery and reuse system based on vacuum spray flash with dibasic acid esters as absorbents

We used dibasic acid esters as the absorbent for a volatile organic compounds (VOC) recovery and reuse system geared mainly toward VOCs from painting and presswork. The system consists of three elements: absorption using dibasic acid esters, separation by vacuum spray flash method, and recovery by condensation. The concentration of both ethyl acetate (EtAc) and isopropyl alcohol (IPA) decreased around 90% at room temperature. Vacuum spray flash was found as a useful process for cost-effective and energy-effective VOC removal system. The difference in the dissolubility parameters (Hansen constant) between dibasic acid esters and VOCs and the boiling point of VOCs was the main contributor to the separation behavior.     

Properties of Poly(Vinyl Alcohol)/Chitosan Nanocomposite Films Reinforced with Oil Palm Empty Fruit Bunch Amorphous Lignocellulose Nanofibers

The objective of this study was to investigate the properties of poly(vinyl alcohol)/chitosan nanocomposite films reinforced with different concentration of amorphous LCNFs. The properties analyzed were morphological, physical, chemical, thermal, biological, and mechanical characteristics. Oil palm empty fruit bunch LCNFs obtained from multi-mechanical stages were more dominated by amorphous region than crystalline part. Varied film thickness, swelling degree, and transparency of PVA/chitosan nanocomposite films reinforced with amorphous part were produced. Aggregated LCNFs, which reinforced PVA/chitosan polymer blends, resulted in irregular, rough, and uneven external surfaces as well as protrusions. Based on XRD analysis, there were two or three imperative peaks that indicated the presence of crystalline states. The increase in LCNFs concentration above 0.5% to PVA/chitosan polymer blends led to the decrease in crystallinity index of the films. A noticeable alteration of FTIR spectra, which included wavenumber and intensity, was obviously observed along with the inclusion of amorphous LCNFs. That indicated that a good miscibility between amorphous LCNFs and PVA/chitosan polymer blend generated chemical interaction of those polymers during physical blending. Reinforcement of PVA/chitosan polymer blends with amorphous LCNFs influenced the changes of T_g (glass transition temperature), T_m (melting point temperature), and T_max (maximum degradation temperature). Three thermal phases of PVA/chitosan/LCNFs nanocomposite films were also observed, including absorbed moisture evaporation, PVA and chitosan polymer backbone structural degradation and LCNFs pyrolysis, and by-products degradation of these polymers. The addition of LCNFs 0.5% had the highest tensile strength and the addition of LCNFs above 0.5% decreased the strength. The incorporation of OPEFB LCNFs did not show anti-microbial and anti-fungal properties of the films. The addition of amorphous LCNFs 0.5% into PVA/chitosan polymer blends resulted in regular and smooth external surfaces, enhanced tensile strength, increased crystallinity index, and enhanced thermal stability of the films.     

Contribution of mangrove detritus to juvenile prawn nutrition: a dual stable isotope study in a Malaysian mangrove forest

Dual stable C and N ratio analyses of primary producers and prawns have clarified the important role of mangrove detritus as the primary food source of juvenile prawns inhabiting the upper estuaries of the Matang mangrove swamp in Malaysia. The contribution of mangrove carbon to prawn tissues, as high as 84%, decreased in the offshore direction, as the contribution by phytoplankton became progressively more important. Prawns located 2 km outside the mangrove swamp still exhibited a dependency of 15–25% on mangrove carbon, but farther offshore (7–10 km) in shallow waters, the prawn's food was basically phytoplankton, with some contribution from benthic microalgae. Comparative stable C and N isotope ratios of tissue and gut contents indicate that prawns basically assimilated what they consumed. Received: 29 February 2000 / Accepted: 26 August 2000     

Process analysis of ozone formation under different weather conditions over the Kanto region of Japan using the MM5/CMAQ modelling system

We have assessed the contributions of individual physical and chemical atmospheric processes on ozone formation under different weather conditions during a typical summer month (August 2005) using the MM5/CMAQ modelling system. We found that the ozone episodes in the Kanto region are dominated by three major patterns, of which Patterns I and II are regular summertime pressure patterns with a 26% and 16% frequency of occurrence, respectively. A process analysis at two typical sites in the Kanto region – one located in the central region of Tokyo and the other located in the rural areas of Kanto – indicates that ozone formation is mainly controlled by advection, vertical diffusion, dry deposition, and chemical processes. The ground-level ozone concentrations are enhanced mainly by the vertical mixing of ozone-rich air from aloft, whereas the dry deposition and chemical processes mainly deplete ozone. By investigating the effects of each process under different weather conditions, we found that the significant decrease in ozone removal due to the chemical and advection processes under conditions of high stagnation is the most important cause of the enhanced levels of ozone in the central region of Tokyo. The results of this study can contribute to a better understanding of ozone formation in the Kanto region, and they may be valuable for local policy makers for further development planning.     

Photodecomposition of humic acid and natural organic matter in swamp water using a TiO2-coated ceramic foam filter: Potential for the formation of disinfection byproducts

This paper reports on the photodecomposition of aqueous humic acid (HA) by a TiO₂-coated ceramic foam filter (TCF) reactor and on the potential for the formation of disinfection byproducts (DBPs) upon chlorination of the photocatalytically treated solutions. This photocatalytic reactor can also be applied to the removal of natural organic matter (NOM) in swamp waters. The proposed photocatalytic reaction system was operated as per standardized methodologies. First, the ability of the TCF to decompose HA (a representative compound of NOM) was evaluated from the changes in the total organic carbon (TOC) and UV₂₅₄ with the reaction time. Remarkably, TOC removal and UV₂₅₄ values ranging from 44% to 61% and from 60% to 83%, respectively, were achieved. The potential for the formation of DBPs (total trihalomethane and total haloacetic acid) by chlorination of the phototreated solution was strongly dependent on the TOC removal and UV₂₅₄ values in the solution. The degree of photodecomposition of NOMs in the swamp water samples and the DBP formation potential showed similar trends as in the case of the standard solutions containing HA. The method used in this study could be effectively used to evaluate the efficiency of TCF for reducing HA and NOM, while suppressing the formation of DBP products.