Sediment tarama işlemi yapılan kentsel bir sulak alanda potansiyel toksik element kaynaklı ekolojik risk analizi: Mogan Gölü (Türkiye)

Öz

Mogan Gölü, Ankara kent merkezinin güneyinde Gölbaşı ilçesi sınırları içerisinde yer alan, 6.5 km2 alan kaplayan bir alüvyal set gölüdür. Son yıllarda gölde ortaya çıkan ve gözle görülür seviyelere ulaşan ekolojik bozulmalar nedeniyle 2017 – 2022 yılları arasında göl tabanında sediment tarama işlemi gerçekleştirilerek ekolojik bozulmaya uğramış sediment tabakası 50 cm kazınıp gölden çıkarılmıştır. Bu araştırma sediment kazıma işlemi yapılan ve yapılmayan bölgedeki ekolojik risk seviyesini karşılaştırmak amacıyla gerçekleştirilmiştir. Araştırma kapsamında gölün farklı noktalarından 25 adet yüzey sedimenti alınmış, PTE konsantrasyonu, toplam organik karbon ve klorofil bozunma ürünleri analizleri gerçekleştirilmiştir. Ekolojik risk seviyesini ve antropojenik etkileri analiz etmek amacıyla zenginleşme faktörü, jeoakümülasyon indeksi, ekolojik risk faktörü ve potansiyel ekolojik risk faktörü hesaplamaları yapılmıştır. Analiz sonuçları mekânsal ve istatistiksel analizlere tabi tutulmuştur. PTE konsantrasyonu ortalama değerlere göre ppm olarak şu şekilde sıralanmıştır: Fe (21300) > Al (19900) > P (630) > Mn (513) > Ni (95) > Cr (62) > Zn (51) > Cu (27) > As (15) > Pb (14) > Mo (1.82) > Cd (0.12) > Hg (0.050). Antropojenik etki değerlendirmesi analizlerinde ortalama verilere göre Pb, Ni, Cu, Cr, Mo, Cd, Fe orta derecede zenginleşmiştir. Noktasal girdiler P ve Hg için orta derecede zenginleşmeye neden olmuştur. Ekolojik risk analizi Mogan Gölü’nde Cd ve Hg kaynaklı, orta derecede potansiyel ekolojik risk bulunduğunu göstermiştir. Çalışmada; gölde yerleşme, tarım ve endüstriyel faaliyetlerden kaynaklanan kirlilik yükünün arttığı, bunun da ötrofikasyonu hızlandırarak ekosistemi tehdit ettiği belirlenmiştir. Sediment tarama sonrası PTE konsantrasyonu ve ekolojik risk düzeylerinde azalma görülse de değerlerin hâlâ risk oluşturduğu, bu nedenle kentsel, endüstriyel ve tarımsal kaynaklı baskıların sıkı biçimde denetlenmesi gerektiği sonucuna varılmıştır.

Anahtar Kelimeler

• Limnoloji
• Potansiyel ekolojik risk
• Mogan Gölü

Ecological risk analysis of potential toxic elements in an urban wetland with sediment dredging: Lake Mogan (Türkiye)

Öz

Lake Mogan is an alluvial dam lake covering 6.5 km2, located within the Gölbaşı district, south of Ankara's city center. Due to visible ecological degradation in the lake in recent years, sediment dredging was carried out between 2017 and 2022, and the degraded sediment layer was removed by scraping approximately 50 cm. This study was conducted to compare the ecological risk level in the area where sediment dredging was performed and the area where it was not. As part of the study, 25 surface sediment samples were collected from different points of the lake, and metal concentrations, total organic carbon, and chlorophyll decay products were analyzed. To analyze the ecological risk level and anthropogenic impacts, enrichment factors, geoaccumulation indexes, ecological risk factors, and potential ecological risk factors were calculated. The analysis results were subjected to spatial and statistical analyses. PTE concentrations were listed in ppm according to average values as follows: Fe (21300) > Al (19900) > P (630) > Mn (513) > Ni (95) > Cr (62) > Zn (51) > Cu (27) > As (15) > Pb (14) > Mo (1.82) > Cd (0.12) > Hg (0.050). According to the average data in the anthropogenic impact assessment analyses, Pb, Ni, Cu, Cr, Mo, Cd, and Fe were moderately enriched. Point sources caused moderate enrichment of P and Hg. Ecological risk analysis showed that there is a moderate potential ecological risk in Mogan Lake due to Cd and Hg. In the study, it was determined that the pollution load on the lake resulting from settlement, agriculture and industrial activities increased, and this threatened the ecosystem by accelerating eutrophication. Although there was a decrease in PTE concentrations and ecological risk levels after sediment screening, it was concluded that the values still pose a risk, therefore urban, industrial and agricultural pressures should be strictly controlled.

Anahtar Kelimeler

• Limnology
• Potantial Ecological Risk
• Lake Mogan

Kaynakça

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