Papers by Shigeki Masunaga
Journal of Japan Society on Water Environment, 2006
ACS Symposium Series, 2016
On the basis of the congener-specific analysis of dioxins in a dated sediment core, surface sedim... more On the basis of the congener-specific analysis of dioxins in a dated sediment core, surface sediment, and soil samples, the sources and mass balance of dioxins in Tokyo Bay basin, Japan, were estimated. The dioxins in the sediment core showed that their deposition in the bay increased rapidly during the 1960s, peaked in the early 1970s and then decreased gradually. Principal component analysis of the congener-specific data showed that three major sources existed: combustion, pentachlorophenol (PCP), and chloronitrophen (CNP). PCP and CNP are paddy field herbicides used extensively in Japan in the past. The time trends of source contributions were estimated by multiple regression analysis using the source congener profiles. The results revealed that dioxin emission from PCP and CNP herbicides was high in the 1960s and the early 1970s, respectively. The mass balance of dioxins in the basin during the past 45 years showed that only a few percent of total dioxin load from agrochemicals were transported to the bay and accumulated in sediment, indicating that large part of dioxins was still remaining in terrestrial soil and river sediment of the basin and running off gradually.
Chemosphere, 2022
Two sediment core samples from the brackish Lake Nakaumi in Japan were analyzed to determine the ... more Two sediment core samples from the brackish Lake Nakaumi in Japan were analyzed to determine the historical profiles of organochlorine pesticides (OCPs). It was observed that from the 1940s to 2005, the vertical distribution of OCPs in sediment cores reflected the temporal trend of pesticide usage in Japan. Dichlorodiphenyltrichloroethane (DDT) and its metabolites were predominant, with concentrations of 0.008-8.27 ng g-1 dry weight, and their contribution to ΣOCPs was over 58%. The results also confirmed that the DDTs in the sediment cores originated from past input. Further, even though hexachlorocyclohexanes were the most used OCP in Japan, their residual concentrations were lower than those of DDTs and chlordane related compounds (CHLs). The concentrations of CHLs were 0.163-1.539 ng g-1 dry weight, whereas hexachlorobenzene (HCB), drins, heptachlor, and mirex showed very low concentrations. Interestingly, although HCB was never registered as a pesticide in Japan, it was detected in both core samples. This HCB contamination might be attributed to pentachlorophenol. Additionally, the hierarchical cluster analysis results corresponding to both sediment cores could be classified under four groups based on a similarity of over 50%. The results also showed that the OCP burden in Lake Nakaumi for the past 60 years was 130 kg and 1153 kg at Honjo and at the center of Lake Nakaumi, respectively. Overall, the results of this study indicate that the distribution of OCPs in Lake Nakaumi reflects the trend of pesticide usage in Japan.
Organohalogen Compounds, 2009
We focused on Decabromodiphenyl ether (DecaBDE), which is known as cost-effective brominated flam... more We focused on Decabromodiphenyl ether (DecaBDE), which is known as cost-effective brominated flame retardant used in TV enclosure components, for the evaluation of risk trade-off caused by the avoidance of its use. Risk trade-off framework, which enables to evaluate and compare the different type of risks, such as human health risk and fire risk is constructed. To date, several governments, especially in EU, make clear that their approach against environmental issue is based on the precautionary principle. Thus, there observed a tendency to place more value on human health risk than physical risk (i.e. fire risk in this case). In the current study, we tried to quantify and compare these risks. At first, we conducted a Cost Benefit Analysis (CBA) considering human health impacts of DecaBDE use and both economic and health damage by TV fires. The results suggested that net benefits of DecaBDE use were positive under all the five scenarios considered. Secondly, we tried to re-evaluate the net benefits of DecaBDE use by replacing the rate of TV fires with more stringent one. Although it diminished fire rate by 75%, under the most realistic two scenarios, results showed positive net benefits of DecaBDE use.
Environmental Engineering Research, 2007
Journal of Hydrodynamics, Ser. B, 2007
... Zu-xin XU and Hai-long YIN, Development of two-dimensional hydrodynamic and water quality mod... more ... Zu-xin XU and Hai-long YIN, Development of two-dimensional hydrodynamic and water quality model for Huangpu River [J], Journal of ... EG RONALD and EY ROBERT, Analysis of the error in the standard approximation used for multiplication of triangular and trapezoidal fuzzy ...
Japanese Journal of Ornithology, 2002
In this paper we outiline the history of toxic contaminants in wild birds in Japan. Pollution by ... more In this paper we outiline the history of toxic contaminants in wild birds in Japan. Pollution by dioxin and dioxin-like compounds has become a common issue in recent decades. As such pollution poses a considerable health probem, countermeasures and technology to reduce the impacts are important. Very few papers have so fare focussed on the effects of dioxin and dioxin-like compounds on wild life in Japan. For the purposes of our research, we selected the Great Cormorant (Phalacrocorax carbo). This fish-eating species nests colonially, and can be regarded as an indicator species of the effects of dioxins and dioxin-like compounds. We monitored cormorant health and compared it with published information on other. The cormorant residue levels were found to be higher than among other birds. The residue of PCDD/Fs consitsted mainly of 2,3,7,8-substitution, in which 1,2,3,7,8-PeCDD and 2,3,4,7,8-PeCDF were the greatest contribution to toxic equivalency (TEQ). These compounds are accumulated more in the liver than egg and muscle. Based on the half-lives of dioxin and dioxin-like compound in the body of the cormorants, a decadal change of pollutant levels of their eggs was calculated using that of the environmental. It seems likely that embryo mortality, caused by dioxins, was the main toxic effect during the 1970s, but this declined dramatically over the following decades. We conclude that the estimated embryo mortality caused by PCDD/Fs and co-PCBs pollution (27%) was so small and would not impact population status. However, studies of the other end points such as LOEL of enzyme activity and immunotoxicity are still needed. Our sample size was small and it is desirable to monitor large number of birds with unlethal techniques.
Water Science and Technology, Sep 1, 1996
The transformation pathways of chloroanilines (CAs), chlorobenzenes (CBs) and chlorophenols (CPs)... more The transformation pathways of chloroanilines (CAs), chlorobenzenes (CBs) and chlorophenols (CPs) were examined in anaerobic sediment collected from the Tsurumi river, Japan. The sediment was pre-exposed to various organic chemicals from the surrounding industries and appears to be sulfidogenic. Experiments were carried out for each compound in the sediment slurry, which was spiked at a desired concentration. The transformation of the parent substrate and the appearance of its metabolites were monitored for a year. All the compounds transformed without any lag period. For CBs, the preferential Cl removal was in the order: two Cl atoms on adjacent carbon atoms > one Cl atom on adjacent carbon > no adjacent Cl atom on the carbon. In case of CPs, ortho dechlorination was the preferred pathway, while for CAs, sequential removal of ortho and para positions was observed.
ABSTRACT As a forward step to understand the metal bio-accumulation in fish species, a study of t... more ABSTRACT As a forward step to understand the metal bio-accumulation in fish species, a study of trace metal speciation of sediment was achieved. Trace metals were measured in sediments and two fish species, Heteropneustes fossilis and Trichogaster fasciata by using inductively coupled plasma mass spectrometer (ICP-MS). Abundance of total trace metals in sediments varied in the following decreasing order: Cr > Ni > Pb > Cu > As > Cd. Sequential extraction tests revealed that the studied metals were predominantly associated with the residual fraction, followed by the organically bound phases. The range of metal content in fishes were Cr (1.8–4.8), Ni (1.0–3.1), Cu (2.5–7.2), As (0.22–0.43), Cd (0.011–0.068) and Pb (0.85–2.7 mg/kg fw), respectively. The rank of biota-sediment accumulation factors (BSAFs) for both species were in the descending order of Cu > Pb > As > Ni > Cr > Cd. Metals accumulation in fish exceeded the international permissible standards suggests that these species are not suitable for human consumption.
Organohalogen compounds, 2000
Environmental Science & Technology, Feb 10, 2012
Environmental Pollution, Mar 1, 2010
The time trend of perfluorinated compounds (PFCs) was determined in sediment core samples collect... more The time trend of perfluorinated compounds (PFCs) was determined in sediment core samples collected in Tokyo Bay. The core sample deposited during 1950s-2004 was divided into two-to three-year intervals. Perfluorocalboxylates (PFCAs), perfluoroalkylsulfonates (PFSAs), perfluorooctane sulfonamidoacetic acids (FOSAAs), fluorotelomer calboxylates (FTCAs), fluorotelomer unsaturated carboxylates (FTUCAs), branched isomers of PFCs, and other compounds were measured. Perfluorooctane sulfonate (PFOS) decreased gradually from the early 1990s while N-ethylperfluoro-1-octanesulfonamidoacetic acid (N-EtFOSAA) and N-methylperfluoro-1-octanesulfonamidoacetic acid (N-MeFOSAA) decreased rapidly in the late 1990s. Perfluorooctanoic acid (PFOA) increased during 1990s. The observed trends were regarded as a reflection of the shift from perfluorooctyl sulfonyl fluoride (POSF)-based products to telomer-based products after 2001 due to the phase out of POSF-based products. Several other characteristics of the PFC trend were obtained: "rapid increase after the early 1970s" for long-chain PFCA (C11-C13); "gradual increase from the 1950s" for middle-chain PFCA (C9-C10); and others. This study revealed that the sediment core can serve as a tool to reconstruct the past pollution trend of PFCs with longer than eight-carbon chain and provides interesting evidence concerning their environmental dynamics.
CRC Press eBooks, Aug 9, 2011
Journal of Japan Society on Water Environment, 2004
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Papers by Shigeki Masunaga