A batch adsorption test was conducted to examine the adsorption characteristics of cadmium and copper on bed sediments of the Sava river and its relation to the concentration of dissolved metals. The adsorption of ions were studied using equilibrium technique as a function of adsorbate concentration. The adsorption data, over the whole range of concentrations used, follow the Langmuir adsorption isotherm. Cu2+ and Cd2+ adsorption isotherms were measured on some sediment samples obtained from 3 different sites.

The paper presents aquatic macroinvertebrate community composition at six investigated localities of the Veliki Rzav river (Serbia). Sampling were carried out during 2005. Characteristics of the macroinvertebrate community with field data were used to estimate the status of the river.

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.

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.

Barje reservoir, established by damming of Veternica river, 30 km upstream from Leskovac town (Serbia), was intended for water supply of communities of Leskovac and Lebane. From its final formation and attaining of maximal volume (1995), long-year investigations have performed, and they included morphometric, chemical and biological parameters (phytoplankton, zooplankton, benthic fauna and ichthiofauna). The results of these hydrobiological investigations have showed that the reservoir Barje is unstable. In according to recommendation for continual following of condition of Barje reservoir, investigations of phytoplankton were repeated in spring and autumn aspects in 2005, and quality of the water was determined on the base of algae. The results of saprobiotic investigations show that the type of water is oligo-beta saprobic, but dense populations of eutrophic species (Fragilaria crotonensis and Closterium aciculare) indicate on deterioration of trophic conditions in this reservoir.

The Bovan reservoir is built on the river Moravica, near Aleksinac (Serbia), primarily for the purpose of water supply. Investigations were carried out during the period of June 2005 to December 2006, with the aim to determine the quality of water, the composition, spatial and time dynamics of communities of microorganisms. The results showed that according to the total number of bacteria in the water reservoir Bovan fall into the category of clean water by Amrazena (1976). By Kohl (1975), water reservoir Bovan belongs to class 2. Summer-time give maximum water characteristics the 2nd-3rd class. Index T/H varies from category to category moderately contaminated clean water. Values heterotrophs percentage representation in the total number of bacteria indicating the great burden of water organic matter.

Introduction of allochthonous species may have noticeable affects on populations communities of native species, ecosystem, but also could result in socio-economic consequences. Therefore, creating and applying risk assessment protocols of aquatic invasive species is a main step in supression of biological invasions. SBC index is used for estimation of biological contamination.

In this article we treat the problemof nonpoint source pollution as a problem of moral hazard in group. To solve this kind of problemwe consider a group performance based tax coupled to tradable permits market. The tax is activated if the group fails to meet the ambient standard. So the role of the tax is to provide an incitation to ensure that the agents provide the abatement level necessary to achieve the standard. The role of the tradable permits market is to distribute effectively this abatement level through the price of the permits which rises with the exchange of the permits.