water mineralization is about 1.25 g L
À1 and water is high in content of sulphates
(680 mg L
À1 ), Fe (31.2 mg L
À1 ) and heavy metals (Andráš et al. 2004a; Šlesárová
2006). Due to the polymetallic nature of the deposit, it can be assumed that the
oxidation of the sulphidic material continues (pyrite is commonly found in
polymetallic ore) and therefore the deposit can be classified as a potential source
of acid mine drainage. The presence of carbonates in the surrounding rocks
contributes to the neutralisation of the acid with calcium carbonate, thereby
preventing more intense acid mine drainage formation. However, the conditions at
the sludge lagoons should be monitored, as the neutralizing potential of the
carbonates can be exhausted, and the character of the acid mine drainage pH may
change towards markedly acid values (Luptáková and Andráš 2018). Such a change
could trigger calamitous degradation process and cause the substantial contamination of the surrounding landscape (Andráš et al. 2004b).
The area in Spiš-Gemer Ore Mt. (Spišsko-Gemerské Rudohorie) chosen for
stream sediment sampling was industrially stressed during the long period of time,
pollution problems caused by mining operations date back to the thirteenth century
(Špaldoň et al. 2006). Large deposits of precious and industrial metals and their
processing characterized this region for centuries, many of these deposits are now
considered as sources of acid mine drainage. Ore deposits in Jaklovce and in the
surrounding area were mainly mined for iron, mercury (cinnabar), copper and silver;
processing of iron ore was conducted in a nearby town of Richňava as well. A
dramatic change in ore processing came with the introduction of the waterwheel, by
which the industry solved the problem of power. This meant that ironworks now had
to be sited next to streams and rivers where there was an adequate supply of water
(Hayman 2016). The ore had to be freighted to the river. Until the second half of the
fourteenth century, furnaces were built on the site of local ore mines. Relocating
works contributed to the further contamination of the river systems in the area. The
valley is polluted with Hg, Cu, As, S and nitrates. Hornád river suffers from a poor
water quality in a long-term sense, heavy copper contamination was detected near
the confluence of the Hornád and Hnilec rivers, and both rivers show high levels of
As, Hg and Zn (Klinda et al. 1994). Apart from geological and industrial points of
view, another reason of reduced environmental quality of the Hornád river valley is
poor environmental awareness of the local community. Inadequate and uncontrolled
disposal of communal and other waste (such as scrap metals, plastics, building
material, chemicals, etc.), particularly discarding of waste on illegal dumps with a
close distance to the river, continues to pose a significant problem (Jablonská et al.
2009).
The collection of sediment samples was carried out in accordance with the
Methodical Instruction of the Slovak Ministry of Environment (1998). Chemical
analyses were performed on fine-grained fluvial sediment, since a number of
pollutants carried by a river tend to bind to a very fine fraction which is being
delivered to the riverbanks and adjacent river channels where it settles as the water
flow velocity decreases, thus allowing pollution to accumulate. The processes by
which benthic organisms stir sediment within the riverbed (i.e. bioturbation)
destroying physical sedimentary structures and creating biological structures occur
158
L. Nemček and I. Hagarová
À1 and water is high in content of sulphates
(680 mg L
À1 ), Fe (31.2 mg L
À1 ) and heavy metals (Andráš et al. 2004a; Šlesárová
2006). Due to the polymetallic nature of the deposit, it can be assumed that the
oxidation of the sulphidic material continues (pyrite is commonly found in
polymetallic ore) and therefore the deposit can be classified as a potential source
of acid mine drainage. The presence of carbonates in the surrounding rocks
contributes to the neutralisation of the acid with calcium carbonate, thereby
preventing more intense acid mine drainage formation. However, the conditions at
the sludge lagoons should be monitored, as the neutralizing potential of the
carbonates can be exhausted, and the character of the acid mine drainage pH may
change towards markedly acid values (Luptáková and Andráš 2018). Such a change
could trigger calamitous degradation process and cause the substantial contamination of the surrounding landscape (Andráš et al. 2004b).
The area in Spiš-Gemer Ore Mt. (Spišsko-Gemerské Rudohorie) chosen for
stream sediment sampling was industrially stressed during the long period of time,
pollution problems caused by mining operations date back to the thirteenth century
(Špaldoň et al. 2006). Large deposits of precious and industrial metals and their
processing characterized this region for centuries, many of these deposits are now
considered as sources of acid mine drainage. Ore deposits in Jaklovce and in the
surrounding area were mainly mined for iron, mercury (cinnabar), copper and silver;
processing of iron ore was conducted in a nearby town of Richňava as well. A
dramatic change in ore processing came with the introduction of the waterwheel, by
which the industry solved the problem of power. This meant that ironworks now had
to be sited next to streams and rivers where there was an adequate supply of water
(Hayman 2016). The ore had to be freighted to the river. Until the second half of the
fourteenth century, furnaces were built on the site of local ore mines. Relocating
works contributed to the further contamination of the river systems in the area. The
valley is polluted with Hg, Cu, As, S and nitrates. Hornád river suffers from a poor
water quality in a long-term sense, heavy copper contamination was detected near
the confluence of the Hornád and Hnilec rivers, and both rivers show high levels of
As, Hg and Zn (Klinda et al. 1994). Apart from geological and industrial points of
view, another reason of reduced environmental quality of the Hornád river valley is
poor environmental awareness of the local community. Inadequate and uncontrolled
disposal of communal and other waste (such as scrap metals, plastics, building
material, chemicals, etc.), particularly discarding of waste on illegal dumps with a
close distance to the river, continues to pose a significant problem (Jablonská et al.
2009).
The collection of sediment samples was carried out in accordance with the
Methodical Instruction of the Slovak Ministry of Environment (1998). Chemical
analyses were performed on fine-grained fluvial sediment, since a number of
pollutants carried by a river tend to bind to a very fine fraction which is being
delivered to the riverbanks and adjacent river channels where it settles as the water
flow velocity decreases, thus allowing pollution to accumulate. The processes by
which benthic organisms stir sediment within the riverbed (i.e. bioturbation)
destroying physical sedimentary structures and creating biological structures occur
158
L. Nemček and I. Hagarová