Environmental Impact of Closing of Oil Shale Mines on River Water Quality in North-Eastern Estonia

Abstract

Chemical and biological characteristics of the Pühajõgi and Kunda catchments were determined in 1995, 2000 During last ten years the concentration of total nitrogen in the samples of the river water from the Pühajõgi catchment has decreased on the average almost 90% since four mines were closed. The concentrations of total nitrogen in the water samples of the Kunda catchment decreased on the average ca 20% during these ten years. The conductivity values of the river water samples of the Pühajõgi catchment between 800 and 1800 µS cm -1 indicated a significant amount of ionic species in the river water. The water was microbiologically unpolluted according to the results of the analysis in 2005.

Relationship Between Water Quality and Oil-Shale Mines in Northern Estonia

“…In the water samples of the Kunda catchment the concentration of nitrate nitrogen formed more than 70% of the total nitrogen concentration (Selberg et al, 2009 The concentrations of ammonia in water sampled from the Kunda catchment had also quite steady ( Table 2). The highest concentration of NH 4 + -N up to 3.1 mmol m − 3 was determined in water sampled from sampling point of Lammasmäe in 1995, but it was below 1 mmol m − 3 in the other sampling points.…”

“…Water was sampled in different points of the main river and streams in 1995, 2000 and 2005, and the sampling was made in July. Summary of results is presented in Tables 8-12 (Selberg et al, 2009, Selberg, 2010.…”

“…The whole catchment is located in the western part of the Estonian oil shale deposit area and large volumes of mine water were discharged into the upper reach of the Pühajõgi River (Vaht & Rätsep, 2009). The Pühajõgi River is not so well studied (Selberg et al, 2009, Vaht & Rätsep, 2009), but it was included into the hydrological field works. Water was sampled in different points of the main river and streams in 1995, 2000 and 2005, and the sampling was made in July.…”

“…The measurements of conductivity and alkalinity were included into the program of the complex hydrobiological field works after 2000, and because of that the values of conductivity and alkalinity of water samples are presented for 2005 only. Methodology of sampling and analysis was described in detail in our publication (Selberg et al, 2009) and it is not repeated here.…”

Impact of Oil Shale Mining on Flow Regimes in Northeast Estonia

“…Selberg et al 2009;Tiwary 2001). Mining has been found to contribute to the dispersal of contaminant metals at local, regional, and global scales.…”