İSTANBUL KIYISAL ALANLARINDA MİKROPLASTİK KAYNAĞI OLARAK SİGARA İZMARİTLERİ ve POTANSİYEL TOKSİK ETKİLERİNİN DEĞERLENDİRİLMESİ

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: İstanbul Üniversitesi-Cerrahpaşa, Lisansüstü Eğitim Enstitüsü, Çevre Mühendisliği Anabilim Dalı Başkanlığı, Türkiye

Tezin Onay Tarihi: 2026

Tezin Dili: Türkçe

Öğrenci: TUĞBA KAYA

Danışman: Nüket Sivri

Özet:

Plastic pollution has become one of the most significant environmental problems threatening aquatic ecosystems on a global scale. Among these pollutants, cigarette butts are among the most frequently discarded anthropogenic wastes released into the environment. Approximately 5.6 trillion cigarettes are consumed worldwide each year, and a substantial proportion of the resulting cigarette butts are directly disposed of into receiving environments. This study aimed to evaluate the role of cigarette butts as a source of microplastics and their toxic effects on aquatic organisms in the coastal areas of Istanbul using both quantitative and qualitative approaches. Florya Güneş Beach and Büyükçekmece Beach, two coastal areas subjected to intense anthropogenic pressure, were selected as the study sites. A total of 5.427 cigarette butt samples were collected from 24 sampling stations during monthly field surveys conducted over a 12-month period between July 2024 and June 2025. The pollution load was quantified using the Cigarette Butt Pollution Index (CBPI), and pollution levels among stations were comparatively evaluated. The calculated CBPI values ranged from 2.52 to 14.78, with the highest pollution level recorded at Büyükçekmece Coastal Station 6 (CBPI: 14.78; Severe). Overall, 45.8% (11 stations) of the 24 stations investigated were classified within the “High” and “Severe” pollution categories.

Structural deformations occurring in cigarette butts as a result of environmental processes, such as UV radiation and mechanical abrasion, were investigated at the molecular level using SEM–EDS and FTIR analyses. Micron-scale surface deterioration of fibers and characteristic spectral band changes were quantitatively identified. The most advanced and aggressive stage of chemical aging was observed in sand-buried samples, particularly at Büyükçekmece Coastal Station 2, where ester bond cleavage and structural degradation of the polymer backbone reached maximum levels due to the combined effects of mechanical abrasion by sand particles and microclimatic conditions associated with heat retention. These findings clearly demonstrated the direct contribution of cigarette butts to microplastic fiber release.

The ecotoxicological component of the study involved bioassays conducted with Daphnia magna (water flea) to evaluate the effects of cigarette butt leachates at different concentrations. The results quantitatively demonstrated that cigarette butt-derived chemicals caused significant physiological alterations and mortality in exposed organisms. Overall, this thesis demonstrates that cigarette butts represent a critical environmental risk factor for Istanbul’s coastal ecosystems, not only due to visual pollution but also because of their contribution to microplastic generation, potential microplastic fiber loading, and the release of toxic substances.