Evaluation of Some Management Strategies in Eutrophic Mogan Lake, Turkey: Phosphorus Mobility in the Sediment-Water Interface

Abstract

Mogan Lake, a popular recreation area, is under the pressure of intense urban-industrial pollution, therefore some management strategies included occasional macrophyte harvesting, diverting running water into the lake to accelerate the improvement of its water, and dredging have been in progressing since 1995. This study was conducted on sediment and overlying water samples collected in April, July and October 2015 and January 2016 from Mogan Lake. The outstanding data for this study is presented as: i) detection of the sediment chemical composition and estimation of sediment phosphorus mobility, ii) comparison of the current status of the lake's eutrophication regarding phosphorus mobility with data from earlier studies regarding the common station. The research data has revealed i) sediment TP concentrations ranged from 620.00 µgP gDW -1 , to 1047.50 µgP gDW -1 while TN concentrations were between 3250.00 µg gDW -1 and 6325.00 µg gDW -1 . Sediment TOC concentrations ranged between 58850.00 µg gDW -1 and 79675.00 µg gDW -1 . Sediment iron content and loss on ignition values were determined as 1.608-3.415 mg gDW -1 and 9.05-20.94 %, respectively. The rank order of phosphorus fractions were evaluated as Ca≈P>Org≈P>CO 3 ≈P>Fe+Al≈P. ii) the phosphorus release values from the sediment (0.1754 -1.1249 mg P m -2 d -1 ) were higher than the earlier studies findings. Phosphorus release in the lake has increased over the past ten years but still remains at a generally low level together with some management activities in Mogan Lake, therefore, instead of the internal P source future research should focus on external sources. In shallow eutrophic systems such as Mogan Lake, sediments having phosphorus accumulation depends on deep interactions with principally antropogenic external sources. In conclusion the primary goal is to determine the adsorption capacity of the sediment in order to estimate the critical internal phosphorus load and the second goal should be to apply a sustainable monitoring program.

Mogan Gölü (Ankara)’nde Sediment Taramasının Yüzey Sedimenti Besin Elementlerine Etkisinin Belirlenmesi

“…Belirlenen maksimum değerin bile Topçu ve Pulatsü (2017)'nin aynı göl sedimenti için belirttikleri maksimum seviyeden (79675 µg/g KA) daha düşük olması, bu parametre bakımından sediment tarama girişiminin belirli düzeyde de olsa indirgenme yönünde etki ettiği şeklinde yorumlanabilir. Mogan Gölü sedimentinde TF konsantrasyonu baz alındığında, Topçu ve Pulatsü (2008, 2017 tarafından bildirilen konsantrasyon değişim aralığı sırasıyla; 286,0 µg/g KA-892,250 µg/g KA ve 620,0 µg/g KA-1047,50 µg/g KA iken bu çalışmada; 700-3200 µg/g KA arasında değişim göstermiştir. Bu durum, sediment tarama girişiminin bu parametre açısından da çok etkin olmadığı şeklinde yorumlananabilir.…”

Use of the Epiphytic Diatoms to Estimate the Ecological Status of Lake Mogan

“…Lake has been heavily influenced by human actions ranging from agricultural and domestic to semi-industrial pollution sources. The lake under the pression of anthropogenic pollution due to the external phosphorus load resulting from detergents in waste water effluents and fertilizers in agricultural run-off from nearby areas (Fakıoğlu and Pulatsü, 2005;Topçu and Pulatsü, 2017).…”