Environmental risk assessment and concentration trend of atmospheric volatile organic compounds in Hyogo Prefecture, Japan

Purpose  

The purpose of this study was to evaluate the influences of volatile organic compounds (VOCs) emissions on hazardousness and photochemical reactivity and to propose efficient VOCs abatement strategies.     

Urinary concentrations of organophosphorus insecticide metabolites in Japanese workers

A recent development in analytical chemistry has enabled us to monitor systemic organophosphorus insecticide (OP) exposure at individual levels. At present, however, limited data are currently available on urinary OP metabolite levels worldwide. The purpose of this study was to assess urinary dialkylphosphate (DAP) concentrations in Japanese workers. Urine samples were collected in both summer and winter from 339 Japanese adults who worked as food distributors (FDs, n = 164), apple farmers (AFs, n = 147) and pest control operators (PCOs, n = 28). DAPs were measured by gas chromatography-mass spectrometry after derivatization with pentafluorobenzylbromide. Dimethylphosphate (DMP), diethylphosphate (DEP), dimethylthiophosphate (DMTP) and diethylthiophosphate (DETP) were detected in the urine of over 87% of the studied populations in both seasons. The geometric mean values of total DAPs (nmol g⁻¹ creatinine), DMP, DMTP, DEP and DETP (μg g⁻¹ creatinine) in summer and winter were 106.7 and 98.3, 7.0 and 3.8, 3.4 and 4.5, 0.8 and 1.5, and 0.3 and 0.2 for the FDs, 440.8 and 197.7, 33.1 and 10.8, 10.1 and 5.8, 4.2 and 4.7 and 1.6 and 0.8 for the AFs, and 473.4 and 284.6, 28.9 and 22.2, 17.6 and 4.6, 3.5 and 4.4, and 0.5 and 0.6 for the PCOs, respectively, thereby revealing significantly higher concentrations in AFs and PCOs groups than in the FDs in both seasons except for winter DMTP. These DAP concentrations were approximately the same or at lower levels compared with those reported in the previous literature. This is one of the first studies to demonstrate urinary DAP concentrations in Japanese adults.     

Blue carbon in human-dominated estuarine and shallow coastal systems

Estuarine and shallow coastal systems (ESCS) are recognized as not only significant organic carbon reservoirs but also emitters of CO₂ to the atmosphere through air–sea CO₂ gas exchange, thus posing a dilemma on ESCS’s role in climate change mitigation measures. However, some studies have shown that coastal waters take up atmospheric CO₂ (C_atm), although the magnitude and determinants remain unclear. We argue that the phenomenon of net uptake of C_atm by ESCS is not unusual under a given set of terrestrial inputs and geophysical conditions. We assessed the key properties of systems that show the net C_atm uptake and found that they are often characteristic of human-dominated systems: (1) input of high terrestrial nutrients, (2) input of treated wastewater in which labile carbon is highly removed, and (3) presence of hypoxia. We propose that human-dominated ESCS are worthy of investigation as a contributor to climate change mitigation.     

Polychlorinated biphenyl (118) activates osteoclasts and induces bone resorption in goldfish

To analyze the effect of polychlorinated biphenyl (PCB) 118 on fish bone metabolism, we examined osteoclastic and osteoblastic activities, as well as plasma calcium levels, in the scales of PCB (118)-injected goldfish. In addition, effect of PCB (118) on osteoclasts and osteoblasts was investigated in vitro. Immature goldfish, in which the endogenous effects of sex steroids are negligible, were used. PCB (118) was solubilized in dimethyl sulfoxide at a concentration of 10 ppm. At 1 and 2 days after PCB (118) injection (100 ng/g body weight), both osteoclastic and osteoblastic activities, and plasma calcium levels were measured. In an in vitro study, then, both osteoclastic and osteoblastic activities as well as each marker mRNA expression were examined. At 2 days, scale osteoclastic activity in PCB (118)-injected goldfish increased significantly, while osteoblastic activity did not change significantly. Corresponding to osteoclastic activity, plasma calcium levels increased significantly at 2 days after PCB (118) administration. Osteoclastic activation also occurred in the marker enzyme activities and mRNA expressions in vitro. Thus, we conclude that PCB (118) disrupts bone metabolism in goldfish both in vivo and in vitro experiments.     

Accelerated biodegradation of nitrophenols in the rhizosphere of Spirodela polyrrhiza

We investigated the biodegradation of 2-nitrophenol (2-NP), 4-nitrophenol (4-NP), and 2,4-dinitrophenol (2,4-DNP) in the rhizosphere of Spirodela polyrrhiza plants by conducting degradation experiments with three river water samples supplemented with each nitrophenol (NP). We then isolated NP-degrading bacteria both from the S. polyrrhiza roots and from the river water. In the river water samples, removal of the three NP was accelerated in the presence of S. polyrrhiza plants. The three NPs persisted in an autoclaved solution with sterile plants suggests that NP removal was accelerated largely by bacterial NP biodegradation rather than by adsorption and uptake by the plants. We isolated 8 strains of NP-degrading bacteria: 6 strains from the S. polyrrhiza roots and 2 strains from river water without the plants. The 2-NP- and 2,4-DNP-degrading bacteria were isolated only from the S. polyrrhiza roots. The 4-NPdegrading bacteria different from those isolated from the river water samples were also found on S. polyrrhiza roots. The 2-NP- and 4-NP-degrading strains isolated from the roots utilized the corresponding NP (0.5 mmol/L) as the sole carbon and energy source. The 2,4-DNP-degrading strains isolated from the roots showed substantial 2,4-DNP-degrading activity, but the presence of other carbon and energy sources was required for their growth. The isolated NP-degrading bacteria from the roots must have contributed to the accelerated degradation of the three NPs in the rhizosphere of S. polyrrhiza. Our results suggested that rhizoremediation with S. polyrrhiza may be effective for NP-contaminated surface water.     

Continuous treatment of azo acid dyes by photo-dependent denitrifying sludge

Simultaneous removals of dye and nitrate by photo-dependent denitrifying sludge(PDDS)have been demonstrated in a continuousflow bench-scale reactor.The best C/N for the degradation of azo dyes by PDDS was 1.5.The specific removal rate of azo dye AB92 decreased with a decrease in hydraulic retention time and increased with a decrease in solids retention time.The degradation rate of TOC decreased with a decrease in hydraulic retention time.AB92,which has nitro and hydroxyl substitutions in non-para positions,was uniquely degraded.During continuous flow treatment experiments using PDDS,complete degradation of azo dyes AB92 and AO20 at influent concentrations of 40mg/L and 30mg/L,respectively,was achieved with an HRT of 16.     

Influence of coexisting surface-active agents on leachability of dioxins in raw and treated fly ash from an MSW incinerator

The leaching behavior of dioxins from raw and treated fly ash (FA) under the coexistence of several types of surface-active agents (SAAs) was examined by batch leaching tests to obtain significant information not only for evaluating leachability of dioxins as hydrophobic organic pollutants (HOPs) under the severe environment in which SAAs coexist, but also for evaluating the reduction efficiency of dioxin-leachability from the treated FA. Enhancement of dioxin-leachability by sufficient addition of SAAs was observed in the leaching test, whereas addition of a smaller quantity depressed the leachability. The higher the degree of chlorination in PCDDs/PCDFs homologues, the more effectively the SAAs enhanced the leachability. Moreover, there was a large difference in the potential for leachability enhancement due to each surface activity, based on critical micelle concentration (CMC) of the SAAs although Aldrich humic acid enhanced the leachability at a much lower concentration than CMC. A comparison of the leachability in FA treated by several methods showed a difference in the reduction efficiency of leachability, depending on the adsorption of SAAs by each treated FA.     

Sensitivity analysis of radionuclide migration in compacted bentonite: a mechanistic model approach

Mechanistic model calculations for the migration of Cs, Ra, Am and Pb in compacted bentonite have been carried out to evaluate sensitivities with respect to different parameter variations. A surface chemical speciation/electric double layer model is used to calculate: (i) porewater composition and radionuclide speciation in solution and at the bentonite surface, yielding the distribution of mobile and sorbed species and (ii) interaction of diffusing species with negatively charged pore walls to obtain diffusion parameters. The basic scenario considers the interaction of compacted bentonite with a fresh-type groundwater; variations include the presence of bentonite impurities and saline groundwater. It is shown that these scenarios result in significant variations of porewater composition that affect migration via three mechanisms that can partly compensate each other: (1) effects on sorption through radionuclide complexation in solution, and competition of major cations for surface sites; (2) changes in radionuclide solution speciation leading to different diffusing species under different conditions; (3) effects on diffusion through changes in the electric double layer properties of the clay pores as a function of ionic strength.     

Leaching of brominated flame retardants in leachate from landfills in Japan

Leachate samples were taken from seven different landfills and concentrations of brominated flame retardants (BFRs), i.e. polybrominated diphenyl ethers (PBDEs) and tetrabromobisphenol A (TBBPA), were quantified. Leaching characteristics of BFRs, especially factors affecting leachability, were clarified to obtain basic information regarding the release of BFRs into the environment. The results obtained for observed levels of the sum of PBDE-47, -99 and -100 were n.d.--4000 pg/l for the raw leachate and n.d. for the treated one, respectively, and those of TBBPA were n.d.--620,000 pg/l for the raw leachate and n.d.--11,000 pg/l for the treated one, respectively. Three sites that not only had crushed material from bulk wastes such as waste electric and electronic equipment, but also were under operation or within a year since closure, indicated a higher concentration of BFRs than the other sites. In particular extremely high concentration of PBDEs was observed at a site with a large amount of organics. Considering the leaching characteristics of BFRs, there exists the possibility that leachability of PBDEs is influenced by the presence of dissolved humic matter (DHM) in the leachate. The high removal efficiency for BFRs in the leachate treatment process was also confirmed.