Investigation of heavy metal pollution in Güllük lagoon

Due to the anthropogenic activities in coastal areas natural ecosystems throughout the world and Turkey are damaged. Güllük Lagoon, located in the Southeast Aegean Sea, plays an important role in terms of ecological and aquatic ecosystem and is under the influence of more than one anthropogenic activities. In this study, sediment samples collected seasonally from April 2018 to January 2019 from 12 stations thoughout Güllük Lagoon were analysed in term of heavy metals concentrations. Chemical fractions of Pb, Cd, Cu, Fe, Mn, Zn and Hg metals in sediment samples and Pb, Cd, Cu, Fe, Mn, Zn and Hg concentrations in plant and fish samples were determined. In order to separate the metals into chemical fractions, the sequential chemical extraction procedure recommended by the Bureau Reference Committee (BCR) was applied and the metal concentrations were measured with AAS. Moreover, for water samples, water temperature, pH, dissolved oxygen, saturated oxygen, electrical conductivity, salinity, BOD5, secchi disk, SSM, nitrite nitrogen, nitrate nitrogen, ammonium nitrogen, orthophosphate phosphorus, total phosphorus and chlorophyll-a analyses were performed. Total heavy metal concentration in the sediment of Güllük Lagoon were as follows: Cu> Mn> Hg> Pb> Fe> Zn> Cd. Heavy metal fraction risk assesment (RAC) were estimated as follows: Cd> Fe> Mn> Zn> Cu> Pb> Hg, pollution level according to Igeo was determined as: Hg> Pb> Cu> Cd> Zn> Mn> Fe. Heavy metal concentrations in fish tissues were determined as: Mugil cephalus> Sparus aurata. The heavy metals detected in the highest concentrations in fish tissues were found as Cu for Mugil cephalus and Mn for Sparus aurata. Heavy metal concentrations in plants were determined as Salicornia europaea> Ludwigia stolonifera. The heavy metal with the highest concentration in both plant samples was again found to be Cu. This shows that there is a relationship between the release of Cu metal in sediment and water, as well as bioaccumulation in plant and fish tissues. The data obtained as a result of the study were mapped with the Geographic Information System (GIS) and evaluated by statistical analyses. As a result, Güllük Lagoon is negatively affected by many major environmental activities. Considering the results of the analysis, it has been determined that there are environmental degradation and pollution in water, sediment, plant and fish samples due to the intense activities in the region especially in the spring and summer seasons. Keywords: Güllük Lagoon, Heavy Metal Fractions, Sequential Chemical Extraction, Water Quality, Anthropogenic Sources, GIS