Page 111 - Çevre Şehir İklim İngilizce - Sayı 3

Mustafa Yücel Evrim Kalkan Tezcan, et al.,

Evaluation of the Latest Situation for 2022

Two more expeditions were carried out in March and May in 2022. In these
expeditions, it was found as a result of the measurements that an ongoing
trend of the oxygen reduction still continued (Figure 1). When we compare
May-2022 with May/June 2021 periods when the mucilage event is ongoing; it
is seen that interlayer transition waters (20-100m) and deep waters of Marmara
Sea, which still combats with the problem of oxygen deficiency for years, do
not contain much more oxygen. Oxygen deficiency continues throughout the
Marmara basin, and it is understood that the oxygen issue left behind by the
mucilage event continues to affect the Marmara Sea. It was observed that the
oxygen-rich undercurrent originating from Strait of Çanakkale is weaker due to
winter conditions, and found that there may be even less oxygen inflow into
Eastern Marmara deep waters in particular, compared to 2021 (Figure 2). This
will be closely monitored with the further expeditions to be performed in 2022.
Marmara Sea sustains its loads with nitrogen and phosphorus nutrients in
2022 as it was in 2021. Only in the Eastern Marmara, a nitrogen loss has started
to occur in deep waters. This is probably due to microbial denitrification
processes as a result of anoxia (Figure 3). It is understood from te fluorescence
measurements in the entire basin that primary formation, increasing in the
spring, becomes thicker in 25m and above (Figure 4). It was observed that
surface formation was getting thicker in the area around Çınarcık Basin at the
center, and there was a substantial formation in the inner Gulf of İzmit (Figure
4). It is thought that the formation in the Inner Gulf of Izmit is due to excessive
nutrient salt load. The formation around Çınarcık Basin is caused by a cycle
combined with the effect of the jet flowing out of the Strait of İstanbul. It was
determined that the relatively less saline water originating from Büyükçekmece
and Küçükçekmece extended to the west. The absence of production along
this flux line suggests that this one is a new flux (Figure 5). During this period,
Marmara basin was divided into two along a line extending from eastern
end of Kapıdağ Peninsula to Tekirdağ in the north. This is due to the large
cycle formed between the Strait of Istanbul and the Kapıdağ Peninsula. This
cycle circulates the surface waters in these borders within itself. This situation,
on the other hand, occasionally causes the waters in the Gulf of İzmit to be
trapped into the gulf.

96 Journal of Environment, Urbanization and Climate