This paper presents the results of the Danube river water quality analysis, using the data set for the period of 2001-2005, provided by the Hydrometeorological Service of Republic of Serbia. Main input parameters - data on water quality resulting from sampling performed generally once per month for relevant parameters, are used according to Water Quality Index (WQI) methodology. Data grouped on a sampling site basis, averaged on a yearly level, resulting with a median WQI of each sampling station are employed to create a synthesized quality indicator. Final result of such an analysis shows a general deterioration of quality expressed using WQI for the observed period.

Scarce natural resources which are important for development of society or civilization itself are the issue of research for economists from the point of view of their efficient utilization. Theory of natural monopoly asserts that for society is better to treat scarce resources as monopoly than to put them on free market. The assertion is that it is better to invest in development of other markets than into free competition in sphere of some scarce resources. Main aim of this paper is to overview some elements of theory of natural monopoly.

There was carried out microbiological analysis of five bottled water of manufacturers from Serbia. Bacteriological quality was estimated using important parameter-aerobic mesophylic bacteria. Two nutrient media were used: standard (PCA) and low nutrient R2A. Plates were incubated at two temperatures (37 deg C and 22 deg C) during 24 hours, 48 hours, 3 days and 5 days. Results show that this group of bacteria is very abudant in bottled waters and their number depends on water types and manufacturers. Moreover, water from different bottles of the same manufacturer has different microbiological quality. Used media, temperatures and period of incubation also have influence on results and R2A medium gives higher values of aerobic mesophylic bacteria.

Water wells are among the oldest hydraulic engineering structures in the world. Today, hundreds of water wells service water supply systems in Serbia, and groundwaters are widely used for public water supply. Extensive practical engineering experience in water well operation has identified a number of problems which affect well service life and capacity (i.e. reduce specific yield). Some of the encountered problems are, also, a result of microbial activity in groundwater. Products of life processes of groundwater specific microbial community cause biocorrosion, blockage, closure, plugging, deposition, and biofouling of well screens and collectors. We applied BART biodetectors as a reliable tool in monitoring well rehabilitation effectiveness. This paper presents several process assessments based on BART biodetector tests conducted at Belgrade groundwater source.

Stable complexes formation caused by usage of complexing agents as additive in plating solutions, made waste water treatment aggravated and expensive. The investigation results of samples that contain some cations expected in waste waters from this type of facilities, are presented in this paper. The precipitation of disolved heavy metals by neutralization, in the presence of strong chelators, do not give requested results. The dithiocarbamates are effective in complexing heavy metal ions forming insoluble compounds, with solubility far below that of the corresponding hydroxides. Inductively Coupled Plasma Optical Emission Spectroscopy is used for wastewater samples analysis. After the reduction of Cr6+ into Cr3+ ions and homogenization, dithiocarbamate is added. Modified neutralization process with unchanged retention time and pH 9.0 +/- 0.2 results the Law permitted wastewater quality.

During technological process of coal treatment and coal improvement in RB Kolubara waste water is produced in the waste water cleansing installation and waste mud is separated. The examination have been executed concerning agrochemical and mechanical properties of this material as well as the presence of heavy metals and phenol. Based on the results which appeard during examination, this materail can be included in the biological reclamation process as bonifactor and deposol fertilizer. Inserting such organic materials, the requared organogenic features are increased and the physical and mechanical characteristics of deposol substrate are improved. The economical effects are important for RB Kolubara as well as for Kolubara-Prerada. The most important contribution is to environmental protection and fulfilling the legal regulations for bringing back of degraded soil to the primary purpose.

Utilization of open-sea industrial fishing techniques in catching small pelagic fish is still undeveloped at Montenegrin coast. Sardines and anchovies, are caught almost exclusively in the coastal area. In Bokakotorska Bay for the least several centuries exists a traditional type of fishery of small pelagic fishes by use of beach seines and artificial light. The Law on Marine Fishery states that the smallest allowed mesh size for catching small pelagic fish is 10 mm, but the fishermen use the mesh openings of 4.5-8 mm diameter as they exclusively collect immature individuals.

Influence of eutrophication to the phytoplankton community were studied in the inner part of Boka Kotorska Bay (Kotor Bay and Risan Bay) from September 2003 to August 2004. Kotor Bay and Risan Bay is very interesting area because the influence of natural and anthropogenic eutrophication are mixed very often. Microphytoplankton density is high (greater than 10**6 cells/cubic dm) what is characteristic eutrophic area, to the highest eutrophic area (greater than 10**7 cells/cubic dm). These values we stated in the surface, because in this layer were the best conditions. In same time we stated very high values: SiO2, oxygen saturation and chlorophyll a. The conclusion is: Boka Kotorska Bay and especially Kotor Bay (as a part of Boka Kotorska) has to be protected of dangerous consequences such as blooming. It is needed to regulate wastewater, their purification and permanent control physico-chemical and biological parameters, and especially phytoplankton component.

In this paper there are presented the results of organic matter index, as dominant component of unsettled water of settlement, which after specified time locate into deeply karst underground appear on spring of river. Obtained results showed that into deeply karst underground has become to certain level of autopurification, which reflecting values of index this loading on the water of spring - river.

Factors controlling of arsenic content in underground water are commented on the base of experimental obtained results of analysis of water quality from October to November 2006. The influence of water quality parameters and temperatures of water on examined locations of waterworks of middle Banat, south from Zrenjanin, public wells in Zrenjanin and waterworks north from Zrenjanin, on arsenic content is found.