Abstract. The impact of Information and Communication Technology (ICT) on economic growth and development has nowadays proven to be significant for almost all national economies. In this paper, a quantitative analysis of the impact of ICT on Croatian economic growth is performed using the input-output (IO) method. The direct and indirect effects of ICT sectors are analysed. Subsequently, simple output multipliers and simple value added multipliers are then calculated. The results indicate that there are no significant differences between the ICT multipliers for the Croatian economy in 2010 and multipliers of other sectors. The largest values of multipliers of all ICT sectors are attributed to the one of ICT service sector. Moreover, significant changes were also not observed when comparing ICT multipliers for the Croatian economy in 2004 and 2010. In addition to Croatia, multiplier analysis of ICT sectors was conducted for the group of new and long-standing European Union member states. The conclusion is that, in new member states, the implementation and usage of ICT has a lower contribution to economic growth and development.

The Neretva River Delta in Croatia is under constant threat of pollution from various sources along the river watercourse, such as the aluminium industry and bauxite mining, intensive agriculture and untreated sewage from towns. The area is also an important fishing ground and food source for the local residents, whereby the suitability of fish for human consumption is always in question. In this paper the presence of arsenic from six sources was analysed: in water, sediment and fish organs (kidneys, liver, muscles and gonads) of 11 fish species: Lepomis gibbosus, Carassius auratus gibelio, Cyprinus carpio, Anguilla anguilla, Ameiurus nebulosus, Mugil cephalus, Leuciscus svallize, Oncorhynchus mykiss, Salmo trutta, Tinca tinca and Scardinius plotiza. The research showed that arsenic concentrations varied significantly from one source to another in the water, sediment and organs of different fish species. Average concentrations in water and sediment were 18.1 lg L )1 and 32.7 lg kg )1 , respectively. Average arsenic levels in the fish organs were 115.9, 105.8, 76.1 and 61.9 lg kg )1 in muscles, kidneys, gonads and livers, respectively. These values are below legally permitted concentrations, although individuals with higher than average concentrations were recorded.

By 2018, in Croatia, the agglomerations for collecting the sewage and water treatment systems are going to be constructed. All devices will be based on the mechanical-biological method of purification. However, the work of water treatment system produces a problem of sludge management. The paper presents the challenges of wastewater sludge handling and makes a decision on further sludge management. The hierarchical model of the decision making problem by defining the goal, criteria and alternative solutions is developed. On each level of the hierarchical model the elements of the model are compared with each other in pairs, and the preferences are expressed by using the Saaty’s scale. Moreover, the APH model compares the alternative pairs (thermal processing, deposition on agricultural land, disposal to waste repositories and composting) among each others. The intensities and weight preferences of one alternative over another are selected within the required criteria (economic, environmental, organisational and sociological).

In terms of a dynamic system, the state of any forest greatly depends on the respective forest management model. Commercial forests, aimed at producing timber, ought to be managed in such a way as to ensure not only the sustainability of income, but also of all the other general benefits to be yielded from such forests. In order to determine whether the current management of a forest's dynamic system complies with the principle of sustainable development, simulation modelling has been applied, including the system dynamics method. Owing to it, the state of the forest as a dynamic system upon implementing a certain management strategy can be forecast.

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