Recent surveys of river Tisza (Serbia) have shown that class Oligochaeta is commonly present as dominant member of benthic macroinvertebrate community. Knowing the fact that this class is very good indicator of organic upload in aquatic ecosystem, in this paper it is used for saprobiological water quality assessment of middle and lower stream of river Tisza in summer of 2002, 2004 and 2005. Results presented as saprobiological indices, showed that water quality of river Tisza (Serbia) was alfa-mesosaprobioc (the third class) during research period.

One of the key issues related to the water quality in the Iron Gate reservoir is the pollution of the sediment. Sediment deposits retained in the Iron Gate reservoir originate from a wide river basin with more then 80 million inhabitants and highly developed municipal and industrial infrastructure. Besides mineral river sediment, various organic and inorganic matters entered and deposited within the Iron Gate reservoir. Sediment research objective was to assess the content of contaminants and nutrients which potentially could enter the water column.

During the spring of 2005, the chemical quality of surface waters and sediments in selected protected areas of Vojvodina (Serbia) was monitored, as a part of the Referent monitoring of the chemical quality of surface waters in Vojvodina during 2005 project. This work presents the results of the referent monitoring and establishes the chemical quality of the surface waters and sediments, and identifies particularly polluted and threatened areas. It is shown that in terms of organic micropollutants content, the chemical quality of the water in the protected areas is in most cases satisfactory, except in the protected areas of Carska Bara, at the Stari Begej Wharf site, and Lake Ludos, where higher mineral oils concentrations were detected. Furthermore, the toluene concentration in Lake Ludos exceeded Canadian guidelines.

The objective of this paper is establishing eco-chemical characterization of the Skadar lake (i.e. Lake Scutari) system by investigation of heavy metal content and distribution in the lake sediments. Factors that influence heavy metal concentrations in sediments are allochthonous (natural and human effects) and autochthonous (natural processes of settling and sorption) as well as transformation of settled substances in sediments. Sediments samples were taken from 15 sites and analysed for copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb).

Investigation of the nutrients and chlorophyll a concentrations, as indicators of trophic level, in the period from September 2003 to August 2004 in three sampling locations in the inner part of Boka Kotorska Bay varied widely. Nitrate concentration ranged from 0.0 to 2.42 mg/l at the surface and from 0.02 to 3.88 mg/l at the bottom, nitrate concentration from 0.02 to 0.21 mg/l at the surface and from 0.01 to 0.6 mg/l at the bottom, phosphate concentration from 0.03 to 0.18 mg/l at the surface and from 0.01 to 0.22 mg/l at the bottom, silicate concentration from 0.0 to 1.42 mg/l at the surface and 0.45 mg/l at the bottom respectively. Value of phytoplankton biomass, as represented by chlorophyll a, ranged from 1.02 to 8.68 mg/cubic meter and from 0.49 to 5.23 mg/cubic meter at the bottom. According to the UNEP criteria during the investigated period it can be concluded that the area in question is mesotrophic with the exception of December when it is eutrophic.

The paper analyses application of different methods for removal of the high content of ammonia from groundwater sources of the Grocka municipality neighborhoods Umcari and Pudarci. According to the relevant data from this field method, biochemical oxidation with the Nitrosomonas and Nitrobacter bacteria was used. Parameters of biological processes of the ammonia oxidation were defined on the pilot model located at the groundwater source. On the pilot model, consisting of a trickling filter and a fast gravel filter, quantitative oxidation NH4 to NO3 was done. Purification plant was designed with parameters of the pilot model, with minimal investment and exploitation expenses, without undesired side products and ecological risks characteristic for procedure of chemical oxidation of ammonia, which recommends this procedure as the optimal solution.