In the scope of the Program of surface water quality examinations in the Republic of Srpska (Bosnia and Herzegovina), hydrometric measurements and water quality examinations had been realized, where zooplankton and microzooperiphyton researches have been performed. Sampling were performed in the period from 6th to 20th May 2000, at 13 water courses with taken in total 21 samples. In qualitative structure of examined fauna, Rotatoria, Cladocera and Copepoda groups were treated, with ascertained in total 109 taxa from 41 genus. In qualitative structure periphyton taxa are predominant. On the basis of bioindicatory species structure it is noticed that dominant species are oligasaprobic and oligobetamesosaprobic character.

Creation of scientific basis for rational use of water resources is impossible without studying viability of the microorganisms, their influence on the formation of chemical properties of natural waters and an explanation of the principles of biochemical processes such as transformation of elements in the aquatic environment. The survey of microbial (bacterial) characteristics of watercourses in the Republic of Srpska was conducted on a total of 64 streams within Operational, International and National surveillance monitoring. Sampling and analysis of samples was performed during the period from May to October. The study included ecological and sanitary aspects of river quality.

Background, aim, and scope Bombing and destruction of the industrial and military targets accompanied by complete or incomplete combustion during the war conflict and NATO operation in former Yugoslavia caused the emission of persistent organic pollutants into the atmosphere, water, and soil. A total of 129 ambient air samples from 24 background, urban, and industrial sites, including hot spots, were collected to assess a gas-particle partitioning behavior of various persistent organic pollutants. Materials and methods High volume sampling technique was applied with quartz filters that collect the atmospheric particles and polyurethane foam filters (PUF) that retain the gaseous compounds. Three to ten samples were taken at each site. GFs and PUFs were analyzed separately for their content of polychlorinated biphenyls, organochlorine pesticides, and polyaromatic hydrocarbons. Results Gas phase and particle phase concentrations of selected persistent organic pollutants (POPs) in all samples were converted into the particle-bound fractions [Greek Phi symbol]. These fractions were found to be highly variable, but generally highest in Bosnia and Herzegovina due to the elevated levels of total suspended material in ambient air. Discussion Experimental values of particle-associated fraction were compared to the Junge-Pankow model. Interestingly, a model for urban/industrial environments provided a better prediction of partitioning behavior than a model for background and rural background sites. That is probably because the total amount of atmospheric particles is higher in the Balkan region than found in the previously published studies. Conclusions Even though it has been stated in previous studies that less than 5% of polychlorinated biphenyls (PCBs) are bound to the particles, up to 67% of PCBs were particle associated at several sampling sites in this study. PCB-contaminated soils are probably still one of the strong sources of particles to the atmosphere. Recommendations and perspectives Information on the particle-bound fractions of POPs is important not only for prediction of their fate but also for an estimation of risks they can pose to the environment as well as to humans. When assessing such hazards, it has to be considered that modeled values of the particle-bound fractions can be seriously underestimated at sites with elevated levels of suspended atmospheric matter or at sites with heavily contaminated soils.

In scope of complex physical-chemical and biological examination of water quality of the Bocac lake, the river Vrbas and tributaries Ugar and Crna Rijeka, examinations of phytoplankton and zooplankton were performed during 2002 (March-November). In qualitative structure of phytoplankton 7 division were registered, with 93 taxa from 49 genera in total. In warmer period extreme domination have fire algae (Pyrrophyta). In zooplankton structure (Rotatoria, Cladocera, Copepoda) 78 taxa were registered from 36 genera, with distinct domination of Rotatoria group. According to saprobiological analysis species of olligo- and beta-mesosaprobic character are prevailing.

According to the plans, the town of Gacko tends to be water supplied from the water reservoir Vrba located at the river Vrba. About 150 to 200 m away is located ash basin. All ash basin area is oriented to the water reservoir and leaking water going directly to the water reservoir. The leaking water has high pH value, alkalinity, high content of sodium, potassium and sulphates. There are some heavy metals, but their concentrations are not significant. The influence of those contaminated water on the lake water quality is only little evident because of the high dilution rate.

In the scope of complex physical-chemical and biological water examination of Bocac water reservoir, the river Vrbas and trbutaries Ugar and Crna Rijeka, examination of standard microbiological indexes of water quality (aerobic organotrophs at 22-26 deg C and 37 deg C, total colliforms and colliforms of fecal origin) was performed during 2002 (March-November). Number of examined microbiological parameters was mainly in the scope of the 2nd water category (beta-mesosaprobic water) with worse water quality in upstream part of the reservoir. Ugar tributary had the best water quality, while Crna Rijeka had the worst status with obvious anthropogenic influence.

Water quality monitoring of surface waters encompasses the watercourses of the river basins of Una, Vrbas, Bosna, Drina, Ukrina and the direct Sava basin. Apart from comprehensive analyses which demand determinations of physical - chemical characteristics, as well as the ihtiofauna composition, special emphasis is given to the analysis of the macrozoobenthos. As a part of all water ecosystems, benthic invertebrate serve as a reliable indicator of the quality and changes of the environment, due to a series of advantages in relation to other communities. Most of the aquatic habitats, especially flowing waters of good quality of water and benthic state, enable various of benthic invertebrates communities with moderate formation of species within the overall number of the present individual species. This kind of communities react to possible changes in the community composition (abundance and macroinvertebrata composition).

In the scope of complex water quality analysis of the Bocac reservoir, as well as rivers which flow into and out of the Bocac reservoir (Vrbas, Crna Rijeka) during the period from May to September 2008, the contents and the dynamics of the phyto and zooplankton were analyzed as biological parameters. The qualitative contents of the phytoplankton includes 5 divisions of total 27 taxa from 16 species; the tributaries contain 30 taxa from 19 genuses. The zooplankton (Rotatoria, Cladocera and Copepoda) contain 22 taxa from 16 genuses; the tributaries contain 32 taxa from 19 genuses with huge dominance of the Rotatoria species. By saprobiological analysis, species of oligo and beta mezosaprobiological character previal.

In the year 2010 ichthyological research on some Vrbas River tributeries located on wider area of Banjaluka city (Bosnia and Herzegovina) was carried out and the occurrence of 14 fish species was recorded. On the basis of the occurrence and abundance of fish species indicators as limnosaprobic parameter, water quality of the analyzed watercourses variated from oligosaprobic to beta mesosaprobic (I and II class of bonity) with saprobic index from 1.27 for Švrakava River to 1.81 for Vrbanja River. The obtained results indicate that water quality of this Vrbas River watershed was on satisfactory level for multiple purposes (in order to sustain ichthyofauna diversity and production and as potential protected areas and spawning zone for some endangered domestic fish species).

Researches of the Zelengora natural lakes during 2008 were performed in Orlovacko, Kotlanicko and the Lake Donje Bare. Water quality analysis of natural lakes of Zelengora were based on preliminary examination of basic physical and chemical parameters, as well as microbiological parameters. In the scope of biological examinations, phytoplankton, zooplankton and benthic fauna were determined. Due to the lack of data on biodiversity of examined natural lakes and whole area of National park Sutjeska results obtained in this research could only represent the first step toward further examinations, as well as the nature and biodiversity preservation in the Republic of Srpska.