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Modeling of fragmentation and mobilization of plastic litter in river basin

流域塑料垃圾破碎与动员模拟

基本信息

批准号：
21H01441
负责人：
片岡智哉
金额：
$ 11.4万
依托单位：
Ehime University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2021
资助国家：
日本
起止时间：
2021-04-01 至 2024-03-31
项目状态：
已结题

项目摘要

本研究は，流域圏における5mm未満のプラスチック微細片（S-MicP）の生成過程と流域圏から河川への流出過程を考慮した流域圏から河川へのS-MicP流出量推定モデルを開発することを目的としている．当該年度ではS-MicP生成過程のモデル化のため，流域圏に散乱する代表的なプラスチックゴミであるペットボトルキャップに着目し，新品のペットボトルキャップ4種を用いた紫外線（UV）促進劣化試験を行い，72時間毎（松山市の紫外線強度で1年分に相当）にウルトラミクロ天秤で質量，共焦点レーザー顕微鏡で表面形状，赤外顕微鏡でIRスペクトルを取得して，質量・表面形状・化学組成の経時変化を得た．これらの結果に基づき，質量・表面形状に関する劣化度モデルを構築し，実際に河川河岸に漂着するペットボトルキャップの野外暴露時間を推定した．さらに，キャップの賞味期限から推定した野外暴露時間と比較したところ，有意な相関があり，モデルの妥当性を確認した．また，屋内外でのペットボトルキャップの暴露試験を行い，デシケータ内（コントロール），屋外及び屋内（水中・日向・日陰・冷蔵庫）の計6箇所に静置し，化学的特性と力学的特性を評価した．その結果，屋外及び屋内（水中）で32週間後に顕著な接触角の増大が見られ，水分による試料表面の劣化が確認された．また，力学的特性では，屋内（冷蔵庫）以外の試料において寒暖差によるキャップの脆化が示唆された．さらに，ソックスレーと溶媒偏析による低分子量化合物の抽出を行い，GC-MS及び1H-NMR測定を行うことで，効果的な添加剤抽出方法について検討した．ソックスレー抽出の1H-NMRスペクトルから芳香族や酸素原子を含む化学構造の存在が示唆され，GC-MS分析の結果，滑剤や可塑剤に由来する化合物と考えられた．溶媒偏析抽出によるGC-MS分析の結果，酸化防止剤や光安定剤が確認された．

The purpose of this study is to develop the estimation of S-MicP outflow from river basins by considering the process of formation and outflow of S-MicP from river basins. When the S-MicP generation process is transformed in this year, the representative of the scattered watershed is selected from the four categories, and the ultraviolet (UV) accelerated degradation test is carried out for 72 hours.(Matsuyama City UV intensity is equivalent to one minute per year) Quality, confocal micro-mirror surface shape, infrared micro-mirror IR selection, quality, surface shape, chemical composition and time change are obtained. The results are based on the quality and shape of the surface, and the degree of deterioration of the surface is estimated. In addition, the evaluation period of field exposure time is compared with that of intentional correlation, and the appropriateness of field exposure is confirmed. The exposure tests inside and outside the house were carried out in six places, including the indoor (indoor), outdoor and indoor (water, sun, shade and cold storage). The chemical and mechanical properties were evaluated. As a result, an increase in the contact angle of the sample outside and inside the house (in water) was observed after 32 weeks, and the deterioration of the sample surface due to moisture was confirmed. The mechanical properties of the specimen outside the room (cold storage) show that the embrittlement of the specimen is caused by the temperature difference between the cold storage and the cold storage. In addition, solvent segregation and extraction of low molecular weight compounds were determined by GC-MS and 1H-NMR. 1H-NMR spectra of aromatic compounds and their chemical structures were analyzed by GC-MS, and the results showed that the chemical structures of aromatic compounds and their plastic compounds were analyzed by GC-MS. GC-MS analysis results of solvent segregation, acidification prevention and photostability were confirmed.