Zoran Nakić

Groundwater Pollution and Quality Monitoring Approaches at the European Level

The authors investigate the sources and processes of groundwater contamination and their assessment within the Drivers-Pressures-State-Impact-Response (DPSIR) framework. Naturally occurring substances, trace elements, radionuclides, nutrients, and salt (sodium chloride) are reviewed with emphasis on the assessment of the natural background load. Some synthetic substances are also considered, these being petroleum hydrocarbons, chlorinated aliphatics, pesticides and organic-waste contaminants. Newly emerging contaminants cannot be described within the DPSIR; therefore monitoring approaches and indicators of contamination are discussed in order to propose improved monitoring plans that combine physical, chemical and biological indicators and combine science with policy.

Fully automated objective-based method for master recession curve separation.

The fully automated objective-based method for master recession curve (MRC) separation was developed by using Microsoft Excel spreadsheet and Visual Basic for Applications (VBA) code. The core of the program code is used to construct an MRC by using the adapted matching strip method (Posavec et al. 2006). Criteria for separating the MRC into two or three segments are determined from the flow-duration curve and are represented as the probable range of percent of flow rate duration. Successive separations are performed automatically on two and three MRCs using sets of percent of flow rate duration from selected ranges and an optimal separation model scenario, having the highest average coefficient of determination R(2), is selected as the most appropriate one. The resulting separated master recession curves are presented graphically, whereas the statistics are presented numerically, all in separate sheets. Examples of field data obtained from two springs in Istria, Croatia, are used to illustrate its application. The freely available Excel spreadsheet and VBA program ensures the ease of use and applicability for larger data sets.

Conceptual model for groundwater status and risk assessment - case study of the Zagreb aquifer system

This paper presents a conceptual model of the Zagreb aquifer system. The conceptual model can be applied to groundwater status risk assessment and pollution risk assessment at the local scale, thus satisfying both environmental and preventative/limitation objectives of the Water Framework Directive (WFD) and Groundwater Directive (GWD). Its main purpose is to apply a risk assessment procedure, according to the WFD requirements, and to serve as a foundation for setting up a numerical model of flow in both the saturated and unsaturated zones in order to identify pressure and impact effects on groundwater quality. The model is divided into two parts, taking into account the WFD requirement to assess a risk for a wide range of source-pathway-receptor relationships. The Global Conceptual Model (GCM) provides insight into the processes and pressures at the level of the groundwater system. It contains the geological and hydrogeological characterization of the Zagreb aquifer system and the description of the most significant point and diffuse sources and pathways of pollution and processes influencing pollutant behaviour in saturated and unsaturated zone of the groundwater system. The main pollutants of the Zagreb aquifer system are potentially toxic metals, nitrates, pesticides, pharmaceuticals and chlorinated aliphatics. A Local Conceptual Model (LCM) supports parameterization of the whole groundwater system through the description of heterogeneities and flow and solute parameters of the system components at two sites representing local conditions in the saturated (Stara Loza) and unsaturated (Kosnica) zones. This concept can be regarded as an effective tool for groundwater management of the groundwater system and its compartments and for communicating the conditions in complex groundwater systems with experts, policy makers and general public in an understandable way.

Definition of the river Gacka springs subcatchment areas on the basis of hydrogeological parameters

The river Gacka springs catchment area is located in the Dinaric karst, which is globally known as the locus typicus, or classical Karst. It is composed of four major and several minor karst springs of different discharge rates. The river Gacka springs are characterised by great discharge and exceptional quality, so the catchment area of the river is indicated in the Water Management Strategy (OFFICIAL GAZETTE NO. 91/08) as an area with strategically important eserves of drinking water for the Republic of Croatia. To determine the hydrogeological characteristics of he subcatchments of this large and complex aquifer system, hydrological and hydrochemical parameters were measured on the main springs. Data collected on the springs were analysed using the recession analysis by the „matching strip“ method, the statistical analysis of a time series of measured data both by autocorrelation (analysis of individual series) and by cross-correlation methods (analysis of interrelationships between time series), multivarilate statistical analysis (Factor Analysis) of hydrochemical parameters using the software package STATISTICA 6.0 (1998), and geochemical modelling of hydrochemical parameters using the NETPATH computer program. Interpretation of lithological, structural and tectonic characteristics of the rocks, together with tracing data and the applied analytical methods, allowed the springs catchment of the river Gacka to be divided into three subcatchments. The results of this study imply the necessity of a multidisciplinary approach to research.

Statistical Indicators of Groundwater Geochemical Characteristics in a Quaternary Aquifer from the Mala Mlaka Well Field Catchment Area (Zagreb, Croatia)

High concentrations of sodium, potassium, nitrates and sulphates in the groundwater in the Mala Mlaka well field catchment area confirm the impact of agricultural activities on water chemistry. Analysis of time trends has shown that a decrease in inorganic components (nitrates and sulphates), which are sensitive to changes in oxidation/ reduction conditions in an aquifer, are caused by infiltration of oxygen- rich water rich in organic matter into the aquifers. Oxygen content reduction due to oxidation of the organic matter causes oxygen deprivation in the groundwater and consequently a reduction in nitrate and sulphate levels. An increase in chloride levels in the groundwater during 1994–2000 is a consequence of human activities in the catchment area. Multivariate statistical analyses, i.e. factor analysis, cluster analysis and multidimensional scaling (MDS) analysis have shown that the registered pollution sources in the catchment area, particularly illegal dump sites, cause degradation of the groundwater quality in some sites. This impact is detected over a distance of several hundred metres downstream from the registered pollution sources.

Environmental geology and hydrology

Abstract Environmental geology is scientific discipline dealing with the interactions between humans and the geologic environment. Many natural hazards, which have great impact on humans and their environment, are caused by geological settings. On the other hand, human activities have great impact on the physical environment, especially in the last decades due to dramatic human population growth. Natural disasters often hit densely populated areas causing tremendous death toll and material damage. Demand for resources enhanced remarkably, as well as waste production. Exploitation of mineral resources deteriorate huge areas of land, produce enormous mine waste and pollute soil, water and air. Environmental geology is a broad discipline and only selected themes will be presented in the following subchapters: (1) floods as natural hazard, (2) water as geological resource and (3) the mining and mineral processing as types of human activities dealing with geological materials that affect the environment and human health.