Nutrient distribution in the Bosphorus and surrounding areas

Abstract

As part of a five years monitoring project "Water Quality Monitoring of the Strait of Istanbul", February-December 1999 nutrient dynamics of the Black Sea-the Sea of Marmara transect are studied to evaluate the effect of discharges given by deep disposals. Through a one-year study, upper layer nutrient concentrations were generally under the effect of northwestern-shelf Black Sea originated waters. This effect was strictly observed in July, when the upper layer flow was the thickest. On the other hand, partly in November but especially in December the northwestern-shelf Black Sea originated water flow was a minimum resulting in similar concentrations in both layers. Nutrient fluctuations also affected the chlorophyll a and POC concentrations as parameters of productivity. The nutrient concentrations decreased with the effect of spring bloom and highest chlorophyll a values were detected in November at Strait stations that did not match to the Sea of Marmara values. This fact represents the time-scale difference between the Black Sea and the Sea of Marmara. On the contrary, high nutrient concentrations in the lower layer (especially inorganic phosphate), and therefore low N:P ratios reflect the effect of deep discharge. Vertical mixing caused by meteorological conditions of the shallow station (M3) under the effect of surface discharges resulted in homogenous distribution of nutrients. Nutrient concentrations of the stations affected by deep discharge showed that the two-layer stratification of the system did not permit the discharge mix to the upper layer.

Mucilage Problem in the Semi-Enclosed Seas: Recent Outbreak in the Sea of Marmara

“…Decarbonization plants and advanced biological treatment facilities do exist; however, they are in the minority (Maryam and Büyükgüngör, 2017). Many studies have shown that this "deep discharge" practice has caused an excess of the nutrient load that exceeds the capacity of the Marmara's marine ecosystem (Okuş et al, 2002;Taş et al, 2016;Çardak et al, 2015). Number and type of wastewater treatment plants in the region are given in the Table 2.…”

Benthic marine litter in the Marmara Sea, Turkey

“…Additionally, Orhon et al (2021) argue that the Black Sea Current in the Bosphorus Strait discharges highly polluted water bodies from the Black Sea into the Marmara Sea. Thus, the nutrient load of the Marmara Sea exceeds the capacity of the Marmara's marine ecosystem (Okuş et al,2002;Taş et al, 2016;Çardak et al, 2015) and results in environmental disasters such as mucilage (Savun-Hekimoğlu and Gazioğlu, 2021).…”