Hydrochemistry of groundwater contaminated by petroleum hydrocarbons: the impact of biodegradation (Vitanovac, Serbia).

Aquifer contamination by petroleum hydrocarbons leads to measurable changes of groundwater hydrochemistry, primarily due to the microbiological activity. This study analyzes this phenomenon at an historical kerosene-contaminated site in Vitanovac (central Serbia). Due to the long-term hydrocarbon contamination and exposure to aerobic and anaerobic biodegradation mechanisms, the lowest concentrations of O2, NO3-, and SO42- (electron acceptors) and the highest concentrations of Mn and Fe (products of microbial metabolic activity) overlap. The terminal redox-accepting processes in groundwater ranged from oxygen reduction to sulfate reduction. The most anoxic processes were registered in piezometers closest to the source of contamination, as was also confirmed by the redox potential (Eh) measurements. High electrical conductivity values and the highest TOC, SiO2, and Al concentrations also overlap in the contaminated zone close to the source of contamination. Scanning electron microscopy study of quartz grains from the zone undergoing the impact of biodegradation confirmed the occurrence of weathering microscale processes on mineral surfaces. Taking all these factors together, it seems reasonable to assume that microbiological activity has caused the enhanced weathering of silicate minerals.

Environmental impact of industrial and agricultural activities to the trace element content in soil of Srem (Serbia).

This study reports the contents and sources of Cu, Hg, Cr, Ni, Co, Zn, Pb, Cd, As, and B pollution in soil samples from Srem in the province of Vojvodina (Republic of Serbia). They are collected in the vicinity of local industrial facilities. The main objective of this study is evaluating the impact of the industrial facilities on the eventual contamination of soils used mostly for agricultural manufacturing. This paper describes the implementation of the combination of methods to estimate the ecological status and determine potential ecological risk. This study applies sequential extraction, pollution indices, comparison with the guidelines, and statistical analysis. Other soil parameters, such as organic matter content, pH, and clay content were measured to evaluate their influence on the trace element content. The investigated soil samples exhibited the raised contents of Ni, Hg, and Cu. Elevated contents of toxic elements observed in localities accommodated within an impact zone affected by industrial complexes, indicating a correlation between the contamination of surrounding soil and potential impact on plants. The most mobile elements are Hg, Cd, and B, while Cr is the least mobile and potential least bioavailable. The results indicate Cr and Ni content increase marking the presence of bedrock, notably in the area of underlying ultramafic rocks and the surface zones influenced by diluvial-proluvial and alluvial processes. The second source of Cr and Ni in the soils of Srem is industrial activities such as leather, cement industry, as well as the metal processing factory.

Assessment of contamination, environmental risk, and origin of heavy metals in soils surrounding industrial facilities in Vojvodina, Serbia.

Content of potentially toxic elements was examined in soils from Srem (Vojvodina), to evaluate industrial facilities as pollution sources. Based on the distribution of the elements, the results of sequential extraction, enrichment factor (EF), ecological risk factor (Er), ecological risk index (RI), and statistical analysis, the current ecological status of the soils was determined. Elements in soils around the industrial facilities can be grouped into the five significant components derived by the principal component analysis (PCA), which explains 78.435% of the total variance. Al, Fe and Mg, and K and Mn are associated with two lithogenic components, respectively. Anthropogenic origin is identified for Hg and Cd. Mixed sources, geogenic and anthropogenic, are identified within two PCA components; one wich includes As, Pb, B, Zn, and the other: K and Cr, Ni and Cu. Cluster analysis (CA) corroborated the results obtained by PCA. The preliminary results revealed that the soils studied in a vicinity of industrial facilities in Srem have been exposed to different degrees of pollution. Among the characterized studied elements, Pb, Cd, Hg, Cu, Ni, and Cr are the main contaminants. Based on calculated EF, the studied soils show minor to severe enrichment with heavy metals. Ecological risk assessment results indicate that Cd and Hg carry the highest ecological risk level, and Zn and Cr the lowest.

Natural attenuation of petroleum hydrocarbons-a study of biodegradation effects in groundwater (Vitanovac, Serbia).

The role of natural attenuation processes in groundwater contamination by petroleum hydrocarbons is of intense scientific and practical interest. This study provides insight into the biodegradation effects in groundwater at a site contaminated by kerosene (jet fuel) in 1993 (Vitanovac, Serbia). Total petroleum hydrocarbons (TPH), hydrochemical indicators (O2, NO3-, Mn, Fe, SO42-, HCO3-), δ13C of dissolved inorganic carbon (DIC), and other parameters were measured to demonstrate biodegradation effects in groundwater at the contaminated site. Due to different biodegradation mechanisms, the zone of the lowest concentrations of electron acceptors and the zone of the highest concentrations of metabolic products of biodegradation overlap. Based on the analysis of redox-sensitive compounds in groundwater samples, redox processes ranged from strictly anoxic (methanogenesis) to oxic (oxygen reduction) within a short distance. The dependence of groundwater redox conditions on the distance from the source of contamination was observed. δ13C values of DIC ranged from - 15.83 to - 2.75‰, and the most positive values correspond to the zone under anaerobic and methanogenic conditions. Overall, results obtained provide clear evidence on the effects of natural attenuation processes-the activity of biodegradation mechanisms in field conditions.

Land degradation at the Stara Planina ski resort.

The environmental impacts of ski resorts in the Balkan region are great and can lead to landscape degradation and loss of land functionality. In this study, we present an example of the negative effects of human activities at the Stara Planina ski resort in southeastern Serbia. The objective of this study is detailed analysis of the characteristics of environmental impacts at the Stara Planina. The management of the ski area and ski slope development caused severe degradation of topsoil and native vegetation. The morphological characteristics of the area, lithological properties of the exposed material and climate conditions resulted in various geomorphic impacts, including rills, deep gullies, solifluctions and debris from rock weathering. Significant changes in land usage altered hydrological conditions, resulting in more frequent torrential floods in the downstream sections of the Zubska River and increased the sediment yield. Environmental impacts were analyzed in the immediate and wider zones of the ski resort in accordance with the specific topography and visual exposure. The restoration and erosion control measures have stopped degradation processes and helped to rehabilitate the appearance and functions of the landscape. The results show the importance of considering lithological (the type and characteristics of minerals present) and hydrological (precipitation, water storage capacity of soil, runoff) factors under the conditions of significant changes in land usage. The results of this investigation can contribute to the improvement of planning processes and the implementation of development projects in ski areas.