Characterization of semi-volatile organic compounds emitted during heating of nitrogen-containing plastics at low temperature

Because of recent volume increases, appropriate management of plastic recycling, which generates various organic compounds, is required to ensure the chemical safety of the processes. The processing temperature and resin type are the important factors determining both the efficiency of the processes and the emission of chemicals. Therefore, we studied the thermal degradation of various plastics at various temperatures from 70 to 300 °C under oxygen-present conditions to identify the semi-volatile organic compounds (SVOCs) emitted and to understand their thermal behaviors. The plastics examined were nitrogen-containing resins, such as polyamide 6, polyurethane, melamine formaldehyde, urea formaldehyde and acrylonitrile-butadiene-styrene. Major commodity plastics were also investigated for comparison. In total, more than 500 SVOCs were detected as emissions from plastics. While various nitrogen-containing SVOCs were detected from nitrogen-containing resins, the major commodity plastics released only these, which possibly were included as additives. These results indicate that the nitrogen atoms in the SVOCs emitted originated from the resins and additives, and not from ambient air at low temperature. As a result of the detection of raw materials, degradation chemicals and by-products of the polymers in the emissions, we found that the variation in chemical species is dependent on the resins. Additives were also emitted from all the resins, meaning that these chemicals were also released to the environment at the temperature examined. In most cases, the numbers and concentrations of SVOCs increased with increasing heating temperature. The variation of thermal behaviors of SVOCs was related to the origins and chemical species of SVOCs.     

Studies on the fusion reaction in two species of Perophora (Ascidiacea)

Histological and electron microscopical studies were made on the fusion reaction between homogeneic stolons of the colonial ascidians Perophora japonica Oka and P. sagamiensis Tokioka. When two stolons make a tip-to-side contact, the epidermal cells of the lateral portion of one stolon become thick and form a protrusion. In the fusion reaction of P. japonica, epidermal cells of each stolon at the contact area extend cell processes immediately after contact. After an occurrence of degenerated epidermal cells, blood interchange between the two stolons is initiated by a partial elimination of the epidermal cells. Even after the establishment of blood interchange, the cuticlelike structure is often observed to remain at the contact area. In the fusion reaction of P. japonica, many amoebocytes are attached to the epidermal cells until the complete elimination of epidermal cells. In the fusion reaction of P. sagamiensis, many lymphocytes as well as amoebocytes are attached to the epidermal cells at the contact area.Contribution No. 461 of the Shimoda Marine Research Center     

Antimony in municipal waste.

Antimony content in municipal waste was studied. Sampled municipal waste was dried, crushed and analyzed. Antimony determinations were performed by Kjeldahl decomposition--batch hydride generation spectrometry and neutron activation analysis. Overall content of antimony in waste was 40-50 g/t raw waste. It was estimated than 20% of the annual production of antimony was discarded as municipal waste in Japan. Leaching of antimony from antimony-added materials may occur, because "small tips" involved considerable amounts of antimony.     

The contribution of azo dyes to the mutagenic activity of the Cristais River

To verify whether dyes emitted within the discharge of a dye processing plant were contributing to the mutagenicity repeatedly found in the Cristais River, Sao Paulo, Brazil, we chemically characterized the following mutagenic samples: the treated industrial effluent, raw and treated water, and the sludge produced by a Drinking Water Treatment Plant (DWTP) located approximately 6 km from the industrial discharge. Considering that 20% of the dyes used for coloring activities might be lost to wastewaters and knowing that several dyes have mutagenic activity, we decided to analyze the samples for the presence of dyes. Thin layer chromatographic analysis indicated the presence of three prevalent dyes in all samples, except for the drinking water. This combination of dyes corresponded to a commercial product used by the industry, and it tested positive in the Salmonella assay. The structures of the dye components were determined using proton magnetic resonance and mass spectrometric (MS) methods, and the dyes were tested for mutagenicity. The blue component was identified as the C.I. Disperse Blue 373, the violet as C.I. Disperse Violet 93, and the orange as C.I. Disperse Orange 37. The dyes showed mutagenic responses of 6300, 4600, and 280 revertants/microg for YG1041 with S9 respectively. A bioassay-directed fractionation/chemical analysis showed that the C.I. Disperse Blue 373 contributed 55% of the mutagenic activity of the DWTP sludge. We showed that these dyes contributed to the mutagenic activity found in the Cristais River environmental samples analyzed and are indirectly affecting the quality of the related drinking water. Therefore, we believe that this type of discharge should be more thoroughly characterized chemically and toxicologically. Additionally, human and ecological risks associated with the release of dye processing plant effluents should be more fully investigated, especially where the resultant water is taken for human consumption.     

Occurrence, distribution, and ecological risk assessment of DDTs and heavy metals in surface sediments from Lake Awassa—Ethiopian Rift Valley Lake

Dichlorodiphenyltrichloroethanes (DDTs) and heavy metals are ubiquitous contaminants with high bioaccumulation and persistence in the environment, which can have adverse effects on humans and animals. Although applications of DDTs have been banned in many countries, developing countries like Ethiopia are still using these for agricultural and medicinal purposes. In addition, heavy metals are naturally present in the aquatic environment and distributed globally. In this study, the occurrence, distribution, and ecological risk of DDTs and heavy metals in surface sediments from one of the Ethiopian rift valley lakes were studied. Twenty-five surface sediment samples from Lake Awassa, Ethiopia were collected and analyzed for DDTs and heavy metals. Results showed that concentrations of total DDTs ranged from 3.64 to 40.2 ng/g dry weight. High levels of DDTs were observed in the vicinity of inflow river side and coastal areas with agricultural activities. The heavy metals content were followed the order Zn?>?Ni?>?Pb?>?Cu?>?Cr?>?Co?>?As?>?Cd?>?Hg. Correlation analysis and principal components analysis demonstrated that heavy metals were originated from both natural and anthropogenic inputs. The levels of DDE and DDD in surface sediments exceeded the sediment quality guideline values, indicating that adverse effects may occur to the lake. A method based on toxic-response factor for heavy metals revealed that the calculated potential ecological risk indices showed low ecological risk for the water body.     

A quantitative risk assessment of waterborne infectious disease in the inundation area of a tropical monsoon region

Flooding and inundation are annual events that occur during the rainy season in Cambodia, and inundation has a strong relationship with human health. This study simulated the coliform bacteria distribution using a hydraulic model and estimated the impact of inundation on public health using a dose–response model. The model parameters were calibrated using field survey data from Cambodia and obtained good agreement with the coliform group count distribution. The results suggest that the impact of inundation on human health is most noticeable in residential areas. The annual average risk of infection during medium-sized flood events is 0.21. The risk due to groundwater use ranges from 0.12 to 0.17 in inundation areas and reaches as high as 0.23 outside the inundation areas. The risk attributed to groundwater use is therefore higher than that for surface water use (0.02–0.06), except in densely populated areas at the city center. There is a high risk for infection with waterborne disease in residential areas, and the annual average risk during small flood events is 0.94. An assessment of possible countermeasures to reduce the risk shows that the control of inundation may bring more risk to public health in Cambodia. Shallower inundation water (<0.3 m) leads to a higher risk of infection, but if the depth is greater than 2 m, the risk is low in residential areas. The simulated results explain the spatial distributions of infection risk,, which are vitally important for determining the highest priority places with relatively high risk and will be helpful for decision makers when considering the implementation of countermeasures.     

Accumulation of Hg and other heavy metals in the Javan mongoose (Herpestes javanicus) captured on Amamioshima Island, Japan

Concentrations of 22 elements (Mg, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Tl, total Hg (T-Hg), Pb) and organic Hg (O-Hg) were examined in the liver, kidney and brain of the Javan mongoose (Herpestes javanicus) and in liver of the Amami rabbit (Pentalagus furnessi) from Amamioshima Island in Japan. Relatively high levels of T-Hg levels (from 1.75 to 55.5 microg g-1 wet wt.) were found in the Javan mongoose. As for a comparison of hepatic T-Hg concentrations between the two areas, there was no significant difference between the Javan mongoose in Amamioshima and those in the Okinawa islands. In addition, T-Hg levels in the livers of the Amami rabbit were the same as in the livers of other herbivorous mammals. Taken together, it suggested that T-Hg accumulation in the livers of the Javan mongoose was not affected by the environment but by a specific physiological mechanism. The comparison of Hg and other heavy metal accumulations between terrestrial mammals (13 species, 61 individuals) including the Javan mongoose and marine mammals (18 species, 508 individuals) were also discussed.     

An intercalibration study on organobromine compounds: Results on polybrominated diphenylethers and related dioxin-like compounds

An intercalibration study on organobromine compounds has been conducted to evaluate the accuracy and reliability in the analysis of brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs) and their related compounds like polybrominated and monobromo-polychlorinated dibenzodioxins and -furans (PBDDs/DFs, MoBPCDDs/DFs). This paper reports the results for these compounds in 'Mixed Standard Solutions' and 'Air-Dried Sediment'. The relative standard deviations (RSDs) for PBDEs, PBDDs/DFs and MoBPCDDs/DFs in mixed standard solutions ranged from 9% to 24%, 4% to 20% and 8% to 27%, respectively. The results of this study are better than those reported in earlier international interlaboratory studies due to general improvement in analytical methods and an increasing number of available authentic standards, particularly for PBDEs. In the analysis for higher brominated compounds such as octabromodibenzodioxin, the participants were advised to optimize the calibration curves befitting the range of concentrations found in samples because variation of relative response factors was noted. The results for 'Air-Dried Sediment' were also reasonable with RSDs from 10% to 38% for PBDEs, 8% to 38% for PBDDs/DFs and 17% to 36% for MoBPCDDs/DFs. In the sediment sample, possible errors in the sample pretreatment and/or interference by other compounds/impurities were indicated. The concentrations of pentabromodiphenylether, BDE100, varied more than the other PBDE isomers due to its poor separation in some chromatographic conditions. In addition, interference by PBDEs was observed in the analysis for PBDFs. Potential degradation/secondary formulation of PBDEs and PBDFs during the Soxhlet extraction were suggested when copper powder was added into the sediment samples. Inspite of these observations, the results in this study are better than those reported in other interlaboratory studies due to the advice given to participants for improving the results. Compared with the results for PCDDs/DFs (5-23% RSDs) and Co-PCBs (6-24% RSDs), the RSDs for most of the organobromine compounds were high, indicating an immature QA/QC approach for the analysis of PBDEs and related compounds in comparison to common chlorinated dioxins.     

Asymptotic growth trajectories of larval sardine (Sardinops melanostictus ) in the coastal waters off western Japan

Growth trajectories of individual larvae of Japanese sardine, Sardinops melanostictus, caught in the coastal waters off western Japan were back-calculated from the first feeding stage up to date of capture (approximate size of 20 to 35 mm total length; TL) based on individually determined allometric relationships between otolith daily ring radii and fish total lengths. The larvae in January-, February-, and March-hatched cohorts in the coastal waters grew faster and more uniformly than those in the oceanic waters offshore of the Kuroshio current. Growth trajectories of the three hatch-month cohorts were similar and could be expressed by the Gompertz model. The inflection points of the growth curves were reached at 9 to 11 d after hatching, when larvae were 10.8 to 11.8 mm TL. Maximum growth rates at these points were 0.80 to 0.85 mm d⁻¹. Growth rates gradually declined after the inflection points, and larval TLs converged into the infinite length of 29 to 32 mm, the sizes at which metamorphosis from larvae to juveniles is initiated. This asymptotic growth pattern in the larval stage resulted in the narrow ranges in TLs in spite of the wide range of ages of the larvae caught by boat seiners in the coastal waters. Slow growth and therefore long duration of the metamorphosing stage could be influential in determining the cumulative total mortality in the early life stages of the Japanese sardine. Received: 14 July 1996 / Accepted: 20 August 1996