Surplus of Nutrients in the Dniester Delta: Where Does it Come From?

Науковий керівник
Назва журналу
Назва тому
We showed that riverine run-offs of N and P to the Dniester estuary and the Black Sea depended on the intensity and dynamics of water mass discharge and on average made 36.6±25.7 Gg N y-1 and 1.3±0.3 Gg Р y-1 in 2010-2013. On average TON made 48.2±13.8% of TN and TOP made 38.2±9.1% of TP emphasizing a large importance of organic constituents, which could be considered as an important source of eutrophication acting with a time delay. We suggested that most of the nutrients (ca. 90%) came to the river upstream from the sampling sites. We found that agricultural sites regularly obtained more deposited inorganic N and P, as well as TN and TP, than natural areas obviously due to local N pollution sources related to management activity. We demonstrated that average contribution of TON to TN was more or less constant (67-71%) between sites but TOP to TP varied in a factor of 2.0 (range: 19.5-40.5%). Imbalance of nutrient N:P ratio to N side (1.75-fold) in riverine water and to P side (1.28-fold) in atmospheric deposition according to the Redfield [9] was brought into focus. One can conclude that significance of organic N contribution to TN in fluvial run-off and atmospheric deposition is crucial and further investigations, as well as long-term monitoring, are urgently needed. This study illustrates that identification and quantification of the main point sources throughout the river flow and quantitative estimation of diffuse sources within the basin, as well as transparent monitoring including water bodies and terrestrial areas especially in “shadow” (not transboundary) areas, is sharply required. The big task is to pay attention and explain to stakeholders (e.g. farmers, businessmen, fishermen etc) how the implementation of good management practices improving the efficacy of nutrients use at a farm/ enterprise scale can be a real win strategy on the one hand saving considerable own funds (economic benefit) and on the other hand positively contributing to the Dniester ecosystem (environmental benefit) leading to the well-meaning consequences for future generations (invaluable benefit). Also, a high priority direction for the removal of excess nutrients from the river ecosystem is the sustainable management of natural, as well as constructed, wetlands, i.e. scheduled vegetation cutting for various purposes (e.g. pellets, sovereign goods, utilization as a green fertilizer). The study was performed in the framework of National research project “To determine the sources and the role of Nitrogen load in the eutrophication of aquatic ecosystems of the Lower Dniester and the Black Sea”. The authors would like to express their gratitude to the staff of Odessa National I. I. Mechnikov University for the assistance in routine sampling.
Ключові слова
Riverine, Nutrients, Nitrogen
Бібліографічний опис
Интегрированное управление трансграничным бассейном Днестра: платформа для сотрудничества и современные вызовы. (Тирасполь, 26-27 октября 2017 г.)