Water Quality Assessment Based on Diatom Indices – Small Hilly Streams Case Study - page 01

Study Area

Rivers Bigar, Jagnjilo, Tisnica and Crna Reka are located in the hilly-mountain part of Eastern Serbia, near the towns of Žagubica, Bor and Majdanpek. This area is situated in the Carpathian-Balkan region of Eastern Serbia, towards the border of the Wallachian-Pontic basin. The investigated watercourses belong to the Danube River Basin and catchments of the rivers Mlava and Pek.

The Jagnjilo River originates as Valja Saka below Čoće at an altitude of 860 m (Gavrilović and Dukić, 2002), which along with the Bigar River forms the Jagnjilo River, that further flows to the north. At the confluence with the River Lipa at Jasikovo village it forms the Veliki Pek River (Gavrilović and Dukić, 2002). The Tisnica River originates at Kučajske Mountain, flows to the north near the eastern slope of Beljanica Mountain. The Mlava River rises from Žagubičko spring after which it immediately receives the Tisnica River as the right tributary (Gavrilović and Dukić, 2002).

The Crna Reka River, which extends almost to the Žagubica-Bor road to the north, is the right tributary of the Tisnica River. The investigated rivers lie on limestone. The Jagnjilo River is the biggest permanent stream, while the Crna Reka River often dries out.

According to the CORINE Land Cover Database for Serbia (Nestorov and Protić, 2006), these streams are situated in an area which is significantly covered in broad-leaved forests and transitional woodland/shrub, while agricultural land is scattered as small agricultural lots.

Material and Methods

Phytobenthos samples were collected during April 2013 from the six localities on rivers in the study area: Bigar (lower stretch), Jagnjilo at two sampling sites (Jagnjilo upper stretch and Jagnjilo lower stretch), Tisnica at two sampling sites (Tisnica lower stretch and Tisnica upstream of the Crna Reka confluence) and Crna Reka (lower stretch) (Figure 1).


Figure 1: Sampling sites at the rivers in the study area


Sampling of benthic diatoms was perfomed according to following standards: EN 13946 standard: Water quality – Guidance standard for the routine sampling and pre-treatment of benthic diatoms from rivers and CEN/TC 230 N 0540: Water quality – Standard for monitoring, sampling and laboratory analysis of phytobenthos in shallow watercourses.

The length of the investigated stretch was 10-20 m at each river. At all sampling sites material was collected from the natural hard surfaces, such as boulders, cobbles and stones. The selected substrate was completely submerged and selected from a zone unshaded by riparian vegetation. Five or more stones were moved to the tray and a surface area of approximately 100 cm2 was scrubbed from each stone. Sampled material was transffered into a sampling bottle and preserved using formaldehyde (HCHO) at a final concentration of 1% to 4%, depending on the quantity of organic matter in the sample.

In the laboratory, according to standard procedure, samples were treated with concentrated sulphuric acid, potassium-permanganate and oxalic acid (Krammer and Lange-Bertalot, 1986). The obtained material was used for permanent diatom microscope slide preparation. Diatom slides were observed using a Carl Zeiss microscope Axio Imager M1, at a magnification of 1000 x and AxioCam MRc5 camera, with Axio Vision 4.8 software.

Qualitative and quantitative analysis of samples was further performed, after the EN 14407: the guidance standard for the identification, enumeration and interpretation of benthic diatom samples from running waters. The method is based on relative abundance (%), therefore 300-500 values on each permanent slide were identified and counted in random transects. For the calculation of diatom indices, OMNIDIA software (Lecointe et al., 1993) was used.

Data analysis for this work is based on IPS – "Pollution Sensitivity Index" (Coste in CEMAGREF, 1982), CEE – "Commission for Economical Community metric" (Descy and Coste, 1991), EPI-D – "Eutrophication and/or Pollution Index – Diatom based" (Dell'Uomo, 2004) and TDI – "Trophic Diatom Index" (Kelly and Whitton, 1995).

Water quality for rivers Bigar, Jagnjilo, Tisnica and Crna Reka after IPS was estimated according to the boundary values given for watercourses of Serbia (Official Gazette of the Republic of Serbia 74/2011). Assessment of water quality classes based on the CEE and EPI-D was performed following Slovakian methodology (available at http://www.vuvh.sk/rsv2/index.php?option=com_content&view=article&id=59&Itemid=68&lang=en) and for TDI based on limit values for Poland, provided in Rakowska and Szczepocka (Rakowska and Szczepocka, 2011).