Quantitative comparison of the influxes of nutrients and organic carbon into the Sea of Marmara both from anthropogenic sources and from the Black Sea

Abstract

The Sea of Marmara, an intercontinental basin with two narrow and shallow straits permitting the exchange of the Mediterranean and Black Sea waters, receives 2.8×104 tons TP (total phosphorus), 2.7×105 tons TN (total nitrogen) and 1.9×106 tons TOC (total organic carbon) per year from the Black Sea inflow, from the lower layer by vertical mixing and from anthropogenic inputs of various origins including riverine discharges. The Black Sea input through the Bosphorus constitutes about 35, 64 and 77 %, respectively, of the total annual loads of TP, TN and TOC entering the Marmara surface waters. Pollution loadings from Istanbul make up a major fraction (40-65%) of the total anthropogenic discharges. The biochemical properties of the productive Marmara upper layer appear to be dominated by the inputs both from its lower layer by vertical mixing and from the Black Sea throughout the year. Pollution discharges from Istanbul have secondary importance for the nutrient and organic carbon pools of the Marmara Sea; however, the land-based chemical pollution has drastically modified the ecosystem of coastal margins and semi-enclosed bays (e.g. Golden Horn, Izmit and Gemlik) where water exchanges with the open sea are limited. Biologically labile nutrients increasingly exported from the Black Sea in the spring-early summer, are compensated by importation from the Marmara Sea through the Bosphorus underflow. The less labile dissolved organic nitrogen and carbon input from the Black Sea appears to reach as far as the Aegean basin of the Northeastern Mediterranean in 4-5 months without contributing to the net production in the Marmara Sea.

Composition and abundance of octocorals in the Sea of Marmara, where the Mediterranean meets the Black Sea

“…Sea has received a significant pollution load in the last 30 years from both the Black Sea inflow and increased anthropogenic input (Tuğrul and Polat 1995). The semi-enclosed Marmara Sea is highly turbid, preventing daylight at very shallow depths (Çoban- Yıldız et al 2000) and the temperature below 20 m is lower (approximately 14.5°C) than at depths of the same range in the Mediterranean, so the conditions are similar to those of higher depths in the Mediterranean Sea.…”

Toxic metal (Pb, Cd, As and Hg) and organochlorine residue levels in hake (Merluccius merluccius) from the Marmara Sea, Turkey

“…Istanbul is the most heavily populated and industrialized metropolitan area of Turkey. In addition to industrial and domestic load from the Istanbul metropolitan area, dissolved and particulate pollution loads from the Danube River are transported towards the Istanbul Strait by shore currents (Beşiktepe et al 1994;Tuǧrul and Polat 1995). The Kocaçay, Gönen and Susurluk Rivers' drainage areas also have large agriculture fields in the Southern Shelf.…”

The Effect of Marmara (Izmit) Earthquake on the Chemical Oceanography and Mangan Enrichment in the Lower Layer Water of Izmit Bay, Turkey

“…DO content of the both the upper and the lower layer slightly decreases in May 2000, together with increasing alkalinity (Figures 4b,7b,8 and 9). The reducing DO content in this month might be related with the water influx enriched with nutrients into İzmit Bay from the Black Sea (via the Marmara Sea) that receives increasing amount of freshwater inflow during spring (Oğuz and Sur, 1986;Tuğrul and Polat, 1995). In August 2000, DO concentration of the water column is significantly reduced (Figures 4 and 6), suggesting the enhanced consumption of DO by decomposition of high organic materials that possibly from the subsequent death of blooming phytoplanktons.…”