The evolution of the eutrophication of the Palić Lake (Serbia)

Eutrophication is a world-wide environmental issue. The Palic Lake is a shallow lake typical for the Pannonian plain. The Lake itself was in a very bad condition during the late sixties of the last century; polluted and hypertrophic. Due to inadequate water quality, it was dried out in 1971 and re-established in 1977 and since then its trophicity has been worsening. The lake has recreational purposes but it is also a collector for treated municipal waste waters coming from the lagoons for active sludge water treatment. The sewage discharges from rapidly developing towns in the watershed and the growing use of fertilizers in agriculture increased the nutrient load to the Lake in the last decades. A steady increase of phosphorus loading is the most important factor of the lake  eutrophication. The result of the accelerated eutrophication is the enormous amount of sediment at the bottom of the Palic Lake. Therefore, in the lake that covers an area of 565 ha and volume of 10 million m3, there was 1.900.160 m3 of sediment. The sediment thickness varied from 0.3 to 1.2 m. In summer 2010, the recreational part of the lake (sector IV) was 1.311.356 m3 of sediment, characterized with concentrations of total phosphorus (TP) of 2885 mg/kg, 4300 mg/kg total nitrogen (TN) and 39000 mg/kg total organic carbon TOC. The sediment of the Palic Lake was not loaded with high concentrations of heavy metals. Everything mentioned supports the fact that the restoration of this aquatic system is necessary and applied measures have to be grounded on the principles of ecoremediation technologies.Key words: Eutrophication, Palic Lake, sediment, total N, total P

Isolation of chromium resistant bacteria from a former bauxite mine area and their capacity for Cr (VI) reduction

The Cr (VI) reducing capacity of bacteria has been investigated in many different soils and waters but little or no information is available from soils originating from bauxite mine areas. From soil, mud and rhizospheres of the floating aquatic plant Potamogeton natans L. and the terrestrial plant Carduus acanthoides L., the Cr content was determined and the microbial populations were sampled. The highest total chromium concentration (204.6 mgkg-1) was found in the rhizosphere of C. acanthoides. To determine the numbers and percentages of chromate-resistant bacteria, the autochthonous microbial populations were subjected to different Cr (VI) concentrations (40, 100, 300 and 1000 mM as K2Cr2O7). At 1000 mM Cr (VI) in the medium, about 25% of bacteria from soil and 45% of bacteria from the rhizospheres were resistant. Of 34 bacterial isolates, within 24 h, only Bacillus stearothermophilus 12 ms, Pseudomonas sp. 12 bk3 and Serratia fonticola 7 be were able to reduce 50 μM Cr (VI). Using prolonged 72 h incubation, they were able to reduce 500 μM Cr (VI) concentrations added to the medium. These chromate-resistant bacteria isolated from rhizosphere of plants growing in bauxite mine soil have great potential for bioremediation of Cr (VI)-polluted wastes.Key words: Chromate-resistant bacteria, chromate reduction, bauxite mine, rhizosphere, plant

Pedological characteristics of open-pit Cu wastes and post-flotation tailings (Bor, Serbia)

To gain a better knowledge of mining areas and potential remediation processes, some characteristics (morphological, physical, chemical and microbiological) of soils formed on open-pit Cu mine waste (OPW) and Cu post-flotation tailings (PFT) dumps were investigated. Soil profiles and surface samples were studied. In general, the investigated soils are characterized by large proportion of coarse soil particles, degraded structure, low humus content, low pH, high As and Cu concentrations, and low soil microbial activity. In all investigated profiles there is no recognizable topsoil layer containing in situ formed humus probably due to soil age, lack of plant cover and organic litter, as well as other unfavorable soil conditions. The specificity of investigated soils is an irregular distribution of some soil characteristics (porosity, humus content, microbiological activity) over depth, which is a result of their technogenic origin. By establishing correlations between the studied surface sample parameters, using principal component analysis (PCA), poorer aggregate properties of PFT than of OPW soils were found, resulting most likely from aggressive mining, i.e., flotation processes. Both OPW and PFT soils compared with control natural soils are characterized by lower clay and humus content, and poorer aggregate properties

Pedological characteristics of open-pit Cu wastes and post-flotation tailings (Bor, Serbia)

To gain a better knowledge of mining areas and potential remediation processes, some characteristics (morphological, physical, chemical and microbiological) of soils formed on open-pit Cu mine waste (OPW) and Cu post-flotation tailings (PFT) dumps were investigated. Soil profiles and surface samples were studied. In general, the investigated soils are characterized by large proportion of coarse soil particles, degraded structure, low humus content, low pH, high As and Cu concentrations, and low soil microbial activity. In all investigated profiles there is no recognizable topsoil layer containing in situ formed humus probably due to soil age, lack of plant cover and organic litter, as well as other unfavorable soil conditions. The specificity of investigated soils is an irregular distribution of some soil characteristics (porosity, humus content, microbiological activity) over depth, which is a result of their technogenic origin. By establishing correlations between the studied surface sample parameters, using principal component analysis (PCA), poorer aggregate properties of PFT than of OPW soils were found, resulting most likely from aggressive mining, i.e., flotation processes. Both OPW and PFT soils compared with control natural soils are characterized by lower clay and humus content, and poorer aggregate properties

The possibility of using macrophytes in lake Palic sediment remediation

Lake Palić is a typical, shallow Pannonian plain lake, with thick sediment layers and high content of phosphorus and nitrogen. The thick layers are the result of accelerated eutrophication, and cause biodiversity loss and disruption of the ecosystem. Numerous methods can be used to overcome the problem of accelerated eutrophication, (sediment removal, phosphorus inactivation etc.). However, these methods have many deficiencies. Lately, using macrophytes as a way to resolve this problem is becoming more and more popular. The aim of this work was to examine the germination possibilities of white mustard (Sinapis alba L.), alfalfa (Medicago sativa L.), oats (Avena sativa L.) and lettuce (Lactuca sativa L.) on Lake Palić’s sediment, as a prescreening test for their suitability for further phytoremediation. The results show that plant species can germinate and grow in early stages in such substrates, so they can be recommended for sediment phytoremediation