The most important indicator of the oxygenation state in water bodies is biochemical oxygen demand (BOD), parameter which indicates the demand of aquatic organisms for oxidizable organic matter in a water body. In addition, ammonium is also a parameter that causes oxygen consumption in water bodies. The indicator “Oxygen Consuming Substances in Rivers” is a state indicator that shows the current status and trends of ammonium (NH4) and BOD in rivers.
The results of the monitoring programs carried out by the Ministry of Agriculture and Forestry in different basins are evaluated according to the criteria specified in the “By- Law on Surface Water Quality Management” (Annex-5, Table 2), and the current status is determined with respect to the parameters BOD and NH4.
The water quality, in general, in the basins where the measurements were carried out, is classified as Class I - II - quality as far as the parameter BOD is concerned. On the other hand, it is observed that the water quality is worse in the Büyük Menderes Basin, which is under strong urban, agricultural and industrial pressure[43].
GRAPH 30- BÜYÜK MENDERES BASIN BIOCHEMICAL OXYGEN DEMAND (mg/L O2)
Source: Ministry of Agriculture and Forestry, General Directorate of Water Management;2021
GRAPH 31- ANTALYA BASIN BIOCHEMICAL OXYGEN DEMAND (mg/L O2)
Source: Ministry of Agriculture and Forestry, General Directorate of Water Management,2021
GRAPH 32- KONYA CLOSED BASIN BIOCHEMICAL OXYGEN DEMAND (mg/L O2)
Source: Ministry of Agriculture and Forestry, General Directorate of Water Management,2021
GRAPH 33- EAST MEDITERRANEAN BASIN BIOCHEMICAL OXYGEN DEMAND (mg/L O2)
Source: Ministry of Agriculture and Forestry, General Directorate of Water Management,2021
GRAPH 34- EAST BLACK SEA BASIN BIOCHEMICAL OXYGEN DEMAND (mg/L O2)
Source: Ministry of Agriculture and Forestry, General Directorate of Water Management,2021
GRAPH 35 - ÇORUH BASIN BIOCHEMICAL OXYGEN DEMAND (mg/L O2)
Source: Ministry of Agriculture and Forestry, General Directorate of Water Management,2021
GRAPH 36- KIZILIRMAK BASIN BIOCHEMICAL OXYGEN DEMAND (mg/L)
Regarding the parameter BOD, it can be said that an improvement in water quality can be observed, especially in 2019, when the change in the basins is considered by year. It can be seen that the water quality in the basins located in the Eastern Black Sea region is at a better level away from the industrial pressure. However, in the Büyük Menderes Basin, where intensive urban, industrial and agricultural activities take place, the water quality is III.-IV. at grade levels.
GRAPH 37– BOD CONCENTRATION CHANGE OVER THE YEARS
Source: Ministry of Agriculture and Forestry, General Directorate of Water Management,2021
GRAPH 38-BÜYÜK MENDERES BASIN NO4-N (mg/L)
Source: Ministry of Agriculture and Forestry, General Directorate of Water Management,2021
GRAPH 39–EASTERN BLACK SEA BASIN NO4-N (mg/L)
Source: Ministry of Agriculture and Forestry, General Directorate of Water Management,2021
GRAPH-40 KIZILIRMAK BASIN NH4-N (mg/L)
Source: Ministry of Agriculture and Forestry, General Directorate of Water Management,2021
GRAPH-41 CHANGE OF NH4-N CONCENTRATION IN BASINS BY YEARS (mg/L)
Source: Ministry of Agriculture and Forestry, General Directorate of Water Management,2021
