Environmental Indicators
Environmental Indicators
6.5- Nutrients in Coastal and Marine Waters

The nutrient indicators show current nutrient concentrations in geographical changes and temporal trends. Discharges of nitrogen and phosphorus from land based sources like urban, industry or agricultural sources cause eutrophication.

Laboratory, Measurement and Monitoring Department of the Ministry of Environment and Urbanization implemented “Integrated Marine Pollution Monitoring Programme” with the coordination of TUBITAK-Marmara Research Center. In the programme, quality and pollution are assessed through various indicators in all of seas of Turkey: Mediterranean Sea, Aegean Sea, Black Sea and Marmara Sea

Marine pollution and quality are assessed in Coastal Water Bodies (CWB).  Coastal Water Bodies or in other words Water Management Unit defines a surface water section, which has been separated according to their typologies that are being determined according to physical, hydromorphological, ecological properties and pressures. They are considered as the smallest management units dealt by WFD.

For nutrient distribution in surface waters total phosphorus (TP), dissolved inorganic nitrogen (DIN), nitrate+nitrite nitrogen (Nox) and silicate (Si) parameters are evaluated in this section.

TP values obtained in the Mediterranean coastal waters in 2017 summer have reflected the river and urban influences and also the “oligotrophic” (TP <0.5 μM) properties of the salty and clear waters not affected such pressures (Graph 47). In some occasions, TP values of stations under the river influence were even lower than 0.5 μM which is accepted as the threshold for eutrophication and where relatively higher values would indicate a tendency towards eutrophic status. In addition, the values of total dissolved inorganic nitrogen (DIN) reached the highest levels (>3.0 μM) at the low salty surface waters of coastal regions (AKD02 and AKD05) affected by terrestrial inputs; while they are in the range from 0.1 to 0.5 μM at the surface waters of the open marine waters; which is quite low and close to the oligotrophic eastern Mediterranean surface water values. The DIN values of bottom waters whose large percentage was composed of nitrate ions resulted from organic matter degradation.

GRAPH 47- MEDITERRANEAN SEA SURFACE WATER NUTRIENT PARAMETERS 2014-2017 COMPARISON

Source: ÇŞB-ÇEDİDGM and TÜBİTAK-MAM (2018). Integrated Pollution Monitoring Project (2017-2019). ÇTÜE 5178702, Report No. ÇTÜE.17.2111 (Mediterranean Final Report, 2017), February 2018, Gebze-Kocaeli.

In Aegean Sea when the nutrient concentrations are assessed seasonally, it is observed that there was no significant difference between the summer and the winter values; however, the measurements of 2017 revealed lower values at all the CWBs (Graph 48). Nox values were observed to be generally low in both seasons; however the concentrations were found to be higher by 2 to 4 times especially at EGE06 (Büyük Menderes River Mouth) and EGE10 (Inner Gulf of İzmir); which could be attributed to the fact that the both CWBs are under river/fresh water input influence. In addition, the Inner Gulf of İzmir is thought to be under the influence of urban discharges. The high concentrations were also detected at EGE15 (exit of the Çanakkale Strait) and EGE16 (Meriç River mouth) in the winter of 2015. In the sampling period, the Meriç river mouth (EGE16) was under the influence of a large river input, while the Dardanelles is thought to be under the influence of the nutrient-rich surface waters coming from the Marmara Sea. Including the 2017 summer samplings, all the samplings revealed that the CWB EGE10 had significantly larger nutrient concentrations than all the other CWBs.

 

GRAPH 48- AEGEAN SEA SURFACE WATER NUTRIENT PARAMETERS 2014-2017 COMPARISON

Source:ÇŞB-ÇEDİDGM and TÜBİTAK-MAM (2018). Integrated Pollution Monitoring Project (2017-2019). ÇTÜE 5178702, Report No. ÇTÜE.17.2113 (Aegean Sea Final Report, 2017), February 2018, Gebze-Kocaeli.

In Black Sea although it is observed that winter periods reveal generally higher levels; the most prominent fact is that the CWBs (2, 7, 10) under the influence of rivers reveal high values of nitrogen and silicate (Graph 49). Besides, KAR08, which is under the influence of Samsun city, reveals a significantly high phosphorus level.

GRAPH 49- BLACK SEA SURFACE WATER NUTRIENT PARAMETERS 2014-2017 COMPARISON

Source: ÇŞB-ÇEDİDGM and TÜBİTAK-MAM (2018). Integrated Pollution Monitoring Project (2017-2019). ÇTÜE 5178702, Report No. ÇTÜE.17.2115 (Black Sea Final Report, 2017), February 2018, Gebze-Kocaeli.

In Marmara Sea it is possible to assert that the nutrient levels revealed higher scores in winter periods than in spring and summer periods (with the influence of vertical mixing); however, there are also some differences between the years (Graph 50). All of the nutrients are at the lowest level in the spring period; which indicate that the primary producers (phytoplankton) consume them. Phosphorus compounds measured at MAR04 (Gulf of Bandırma) indicated the highest level in all seasons, which reveals the permanent existence of industrial and domestic pressures. **Besides, relatively high nitrogen compounds and silicate were detected at the CWBs (1-2-20-21) under the influence of Susurluk River.

 

 

GRAPH 50- MARMARA SEA SURFACE WATER NUTRIENT PARAMETERS 2014-2017 COMPARISON

 

Source: ÇŞB-ÇEDİDGM and TÜBİTAK-MAM (2018). Integrated Pollution Monitoring Project (2017-2019). ÇTÜE 5178702, Report No. ÇTÜE.17.2116 (Marmara Sea Final Report, 2017), February 2018, Gebze-Kocaeli.