有機スズ化合物の海域環境における挙動と魚類による生物濃縮に関する研究

山田, 久

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有機スズ化合物の海域環境における挙動と魚類による生物濃縮に関する研究

https://fra.repo.nii.ac.jp/records/2002395

Item type

紀要論文 / Departmental Bulletin Paper(1)

公開日

2024-04-22

タイトル

有機スズ化合物の海域環境における挙動と魚類による生物濃縮に関する研究

言語

タイトル

Studies on Behaviour of Organotin Compounds in Marine Environment and Bioaccumulation by Marine Fish

言語

jpn

キーワード

言語

主題Scheme

Other

主題

organotin; global distribution; marine environment; marine fish; bioaccumulation kinetics; water criteria

資源タイプ

資源タイプ識別子

http://purl.org/coar/resource_type/c_6501

資源タイプ

departmental bulletin paper

アクセス権

open access

アクセス権URI

http://purl.org/coar/access_right/c_abf2

著者

山田, 久

抄録

内容記述タイプ

Abstract

内容記述

Organotin compounds have been widely used in diverse industries as biocides, heat stabilizers for polyvinyl chloride (PVC), and catalysts in a variety of chemical reactions. It was recognized by experiments using mammals that lesions in the liver, kidney, brain, and nervous system were caused by the organotin compounds. Several kinds of acute and/or chronic toxicity such as mortality, supression of growth, imposex of snails, decrease in fertilization of oyster eggs, and supression of gonadal maturity of fish etc. were recognized in many aquatic organisms. Organotin compounds are known to be considerably bioaccumulated in fresh water fish, however, only a few reports have been published for the bioaccumulation of organotin compounds in marine fish. The bioaccumulation chracteristics of organotin compounds by marine fish and the behaviour in the coastal environment are not clarified. Therefore, the purpose of this study was to investigate (a) distribution and behaviour in marine environment, (b) bioaccumulation kinetics and metabolism in marine fish, and (c) biomagnification through the coastal marine food chain in order to elucidate the countermeasure to the organotin pollution in marine environment. 1. Global distribution and behaviour in coastal waters The current status of global marine pollution by tributyltin (TBT) and triphenyltin (TPT) was examined by determining their concentrations in squid liver and their global distributions were compared with polychlorinated biphenyls (PCBs). TBT and TPT concentrations in squid livers were higher in coastal waters than in open oceans. The highest values of TBT and TPT of 279 and 519 ng/g, respectively, were detected off Japan. TBT concentrations were higher in the northern hemisphere than those of the southern hemisphere squids. TPT was not detected in squid livers collected in the southern hemisphere. The variation in TBT and TPT concentrations between the northern and the southern hemisphere was greater than those recognized for PCBs distribution in the world oceans. This global distribution pattern of TBT, TPT and PCBs seemed to reflect their usage (amount, period and manner of utilization). TBT concentration in seawater changed seasonally in accordance with application of TBT containing paint on ship bottom, and it was higher in early summer at coastal area near the yacht harbour in Aburatsubo Bay. TBT was incorporated into the suspended materials through the bioaccumulation by phytoplankton, and was eventually accumulated in the bottom sediments through the deposition of the suspended TBT. 2. Procedure of bioconcentration experiments using marine fish Several kinds of experimental conditions such as fish species, body weight of fish, water temperature, density, and feeding rate etc. were examined in order to establish the experimental procedures using marine fish. Red sea bream and sand borer accumulate a large amount of organic hazardous chemicals, on the contrary, the higher bioconcentration factor (BCF) of heavy metals were recognized in file fish. Uptake rate constant (k1) and the elimination rate constant (k2) declined with a increase of a body weigth of fish. k1 and k2 at 25°C was larger than that at 20°C, however, BCF, which is expressed as k1/k2, was independent on these experimenatal condiotion. The present results indicated that suitable body weight of test fish for bioconcentration experiment is 2-5 g for sand borer and 2-10 g for red sea bream. The present study also indicated that both 20 and 25°C were suitable for the bioconcentration experiment using these fish, and that body weight and/or water temperature in the experiment, in which determines k1 and k2, should be fixed exactly. Suitable density (<4.6 g/l of aquarium capacity and <0.3 g/l of daily used seawater volume) and the suitable feeding rate (<4% of body weight) was determined. These results were used in the experiments carried out in the chapter 3. 3. Bioaccumulation, metabolism and elimination of organotin compounds BCFs of TBTO and TPTCI by marine fish were larger than those in freshwater fish, and BCF of TBTO and TPTCI was 9400 and 3300, respectively. The BCF of TBTO was largest value among the BCFs determined by marine fish, and larger BCFs were generally determined in fish having smaller elimination rate constant. BCFs of TBT compounds as TBTCI, TBTF and TBTBr etc. were smaller than that of TBTO, and did not change by kinds of anionic ion combined with tin atom. Moreover, relationships between BCF and octanol/water partition coefficient (Pow) was not recognized in TBT compounds. It was supposed from these results that TBT compounds were dissolved in seawater in the form of TBT ion, and that the mechanism of bioconcentration was different from those of organic hazardous chemicals such as PCBs. Red sea bream bioaccumulated TBT and TPT compounds in feed by dietary uptake, and the biomagnification factor (BMF) were 0.26 to 0.38 for TBT and 0.57 for TPT. BMF was not significantly altered by the concentration nor the species of chemicals in the feed. The tissue distribution TPT in red sea bream was not altered by the uptake pathways of dietary uptake and direct uptake from water, and no correlation was found between lipid content and the concentration of TBT or TPT in fish. These results also suggest that bioaccumulation of organotin compounds is similar to those of heavy metals rather than the organic hazardous chemicals such as PCBs. The TBT accumulated in red sea bream was metabolized by the drug metabolizing enzyme (cytochrome p450) existing in the microsomal fraction of liver. Butyl base was separated from tin atom after the hydroxylation, and these matabolic pathways were similar to those recognized in mammals. When TBT in muscle of red sea bream was fractionated into two fractions of lipid fraction and the residual fraction after extraction of lipids, relatively large amount of TBT was detected in the residual fraction. The TBT concentration in the residual fraction did not excreted in the elimination experiment. These results suggested that TBT combined to the connective tissue was not easily released from the fish, and that the metabolism and liberation of TBT depended on the behaviour and the chemical form (combination with protein) of TBT in organisms. TBT and TPT were accumulated in polychaetes from sediments, and moreover, TPT was accumulated in organisms of higher trophic level through the food chain. Since deposition of TBT to sediments was recognized from the survey in Aburatsubo Bay, it was pointed out that organotin pollution was prolonged by the transfer of organotin compounds to organisms from sediments. 4. Conclusions The accumulation of organotin compounds were different from that of the organic hazardous chemicals such as PCBs on the several points described in the above section. It was concluded from these results that the bioaccmulation of organotin compounds were similar to methylmercury and several kinds of heavy metals, because organotin compounds exist in seawater and organisms in the form of cation. The TBT and TPT were transfered to the fish by the dietary uptake from the food, and TPT was bioaccumulated in the higher trophic organisms through the food chain. It was also shown that organotin compounds in sediments were transfered to the bottom dwelling organisms through the ingestion of sediments by these organisms. It was pointed out from the present results that improvement of sediment contamination is one of the important research in order to recover the marine pollution by organotin compounds. Allowable organotin concentration in seawater for the production of fish and shellfish suitable for the food is determined from the viewpoint of human health by using allowable daily intake of organotin compounds, feeding rate of fish and shellfish, and the bioaccumulation facter. Allowable concentration was 89 ng/l for TBT, and 56 ng/l for TPT, and these values were higher than the concentration causing the imposex in snail. These results suggest that the seawater area satisfying the water quality criteria of organotin compounds (2 ng/l) is appropriate for the production of fish and shellfish for the food.

言語

bibliographic_information

ja : 瀬戸内海区水産研究所研究報告
en : Bulletin of Fisheries and Environment of Inland Sea

巻 1, p. 97-162, ページ数 66, 発行日 1999-03

出版者

瀬戸内海区水産研究所

言語

出版者

National Research Institute of Fisheries and Environment of Inland Sea

言語

item_10002_source_id_9

収録物識別子タイプ

PISSN

収録物識別子

1344-8579

item_10002_source_id_11

収録物識別子タイプ

NCID

収録物識別子

AA1138042X

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有機スズ化合物の海域環境における挙動と魚類による生物濃縮に関する研究

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