Assessment of water and sediment characteristics of the Northern Danube Delta Lakes - Matita, Babina and Merhei, Romania

Abstract

At the end of its course of 2857 km running to the Black Sea, the Danube River - the longest river in the European Union shapes a river delta, an exclusive area consisting of a complexity of water and land, numerous lakes, ponds, marshes and unique waterways. The Danube Delta, considered the Europe's largest wetlands, is included in Unesco's World Heritage list, due to its outstanding importance conferred by the many natural habitats with their specific characteristics and bio diversities, preserved in a near pristine state. Even though considerable conservation efforts have been made lately, the Danube Delta is still subject to threats due to both natural and anthropogenic stressors that may alter its ecosystems. This study aims to investigate the water and bed-sediment general characteristics of some lakes from the Matița - Merhei Depression located in the fluvial delta plain, to assess the current quality status of water and sediments. A significant number of water and sediment samples were collected from each lake in October 2016, for determination of water physicalchemical parameters, lithological components and some heavy metals - analysed in random bed-sediment samples. The investigation results show that the water environment-related indicators fluctuated in terms of sampling sites and generally agreed with the Romanian environmental quality criteria. Average lithological composition of the bed-sediments indicates an autochthonous source for the recent accumulation of sediments. Overall, the technophyllic heavy metal concentrations of the bed-sediments were below the limits of the quality criteria. The exceptions were represented by local values, incidentally exceeding the recommended limit.