To examine the status and risk of heavy metal pollution, the distribution of As, Cd, Cr, Ni, and Pb in the sediment of Lake Uluabat was characterized. The present study used a four-stage method to assess the ecotoxicological effects of the heavy metal and trace elements fractions in the sediment of Lake Uluabat. Total Cr and Ni concentrations in the sediment were determined to have exceeded the severe effect level (SEL) limit values. The percentages of the variable fractions of Cr and Ni were below 10%. Because of this reason, they were not defined to have a high risk. The relationships among the physicochemical parameters, heavy metals and trace elements in water and sediment were determined statistically. Pb, Cd, and As in the water were found in relation with some of the fractions. Moreover, it was thought that the amounts of the elements of As releasing into the water might be increased due to their relations with the physicochemical parameters.

Lake Uluabat is one of the most important wetlands in Turkey because of its rich biodiversity, lying on a migratory bird route with almost all its shores being covered by submerged plants. The lake has been protected by the Ramsar Convention since 1998. However, the Lake is threatened by natural and anthropogenic stressors as a consequence of its location. Geographic Information System (GIS) analysis is a tool that has been widely used, especially for water quality management in recent years. This study aimed to investigate the water quality and determined most polluted points using GIS analysis of the lake. Temperature, pH, dissolved oxygen, chemical oxygen demand, Kjeldahl nitrogen, total phosphorus, chlorophyll-a, arsenic, boron, iron, and manganese were monitored monthly from June 2008 to May 2009, with the samples taken from 8 points in the lake. Effect of pH, relation of temperature, and Chl-a with other water quality parameters and metals are designated as statistically significant. Data were mapped using ArcGIS 9.1 software and were assessed according to the Turkish Water Pollution Control Regulations (TWPCR). The research also focused on classifying and mapping the water quality in the lake by using the spatial analysis functions of GIS. As a result, it was determined that Lake Uluabat belonged to the 4th class, i.e., highly polluted water, including any water of lower quality. A remarkable portion of the pollution in the water basin was attributed to domestic wastewater discharges, industrial and agricultural activities, and mining.

This article presents the result of investigation on the spatial and temporal changes in water quality of Uluabat Lake. It examines the relationship between water and sediment quality parameters, and assesses the factors affecting eutrophication. Water and sediment quality are examined at 8 stations in the lake between May 2008, and May 2009. Water and sediment quality parameters measured are T, pH, EC, SD, NH4-N, NO3-N, TN, PO4-P, TP. Also DO, alkalinity, hardness, SS, BOD, COD, Chl-a parameters in water and organic matter content in sediment are measured. SS, Chl-a, TP concentrations showed their maximum value in the summer (122.75 mg L-1 , 43.87 mg m-3 and 0.48 mg L-1 respectively), and their minimum value during winter (12 mg L-1 , 6.80 mg m-3 , 0.076 mg L-1 respectively). TN indicated a maximum concentration in summer (23.23 mg L-1) and a minimum during spring (3.89 mg L-1). This study reveals the importance of relationships between temperature DO and nutrients in water. Effect of pH, relation of temperature, conductivity with all nutrients in the sediment, and the differences between the seasons are designated as statistically significant. Water pollution has measured extremely high in station 8 according to Chl-a, BOD and COD parameters, and station 1 indicates the same situation with respect to nitrogen parameters. The results revealed the importance and the need for strict control of point and non-point pollution loads for the preservation of the Uluabat Lake's water quality. Compliance requirements should be set up for activities that could adversely affect water quality.

Pestisit endüstrisi atıksularının toksik etkilere ve biyolojik birikime neden olması ve bu atıksuların yüksek kimyasal oksijen ihtiyacı (KOİ) ve askıda katı madde (AKM) konsantrasyonları çevresel açıdan önemli problemlere yol açmaktadır. Ayrıca, pestisit endüstrisinde üretilen pestisitlerin türüne ve kullanım özelliklerine göre atıksuların karakterizasyonu değişebilmektedir. Bu çalışmada yaygın ve ekonomik olarak kullanılan alum (Al2(SO4)3.18H2O), demir (II) sülfatın (FeSO4.7H2O) ve demir (III) klorür (FeCl3.6H2O) koagülantları ve anyonik polielektrolit (magnaflok) ile koagulasyon flokulasyon prosesi ile fizikokimyasal arıtabilirlik çalışması yapılarak atıksuyun üretimde yeniden kullanımı değerlendirilmiştir. AKM ve KOİ giderilmesinde koagülasyon-flokülasyon prosesinin giderim sağladığı ancak alıcı ortama deşarj için çok yeterli olmadığı görülmüştür. Demir (III) klorür, alum ve demir (II) sülfat için optimum pH değerleri sırasıyla 7,21, 8,12 ve 7,18 ve optimum koagülant dozajları demir (III) klorür ve demir (II) sülfat için 250 mg/L, alum için ise 300 mg/L olarak bulunmuştur. KOİ giderim verimleri demir (III) klorür, alum ve demir (II) sülfat için % 43, % 47 ve % 42, AKM giderim verimleri ise, demir (III) klorür için % 44, alum için % 47 ve demir (II) sülfat için % 39 bulunmuştur. Optimum polielektrolit dozları alum ve demir (II) sülfat için 0,2 mg/L, demir (III) klorür için ise, 0,3 mg/L olarak belirlenmiştir. Sonuç olarak bu koagulasyon-flokulasyon prosesi sonucunda elde edilen suyun geri kazanılarak üretimde kullanılabileceği belirlenmiştir.

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