Mathematical modles and adequate investigation works enables successful water quality modeling. These models includes all relevant abiotic components (concentration of dissolved oxygen, temperature regimes and temperature stratification, concentration of organic and inorganic components of physical-chemical water conditions), while the biotic components are present only with phyto- and zooplankton. In new water reservoir, ichthyofauna mostly undergo mancontrolled successions, starting with planned stocking a water reservoir with fish. The paper presents analytical approach for mathematical modeling of ichthyofauna and application of Lotka - Volterr's equations.

One of the very dangerous pollution of environment are heavy metals. They are "indestructible" at the condition which leads at the environment. Pollution of heavy metals is irreversible process, except if they are physical removed from the environment which they are polluting. We determinated heavy metals (Pb, Cd, Cu, Zn, Cr, Ni and Co) in the mud of three fish ponds by means of sequential extraction, because of possible mobility in the mud and its concentration increase in the water. This method was selected because we wanted to determine distribution of heavy metals by substrates, and analyse was worked by the method of AAS. The results are showing that the concentration of all metals is in the extent of "natural phone" of lakes sediment.

Paper points the present water quality of the Moraca river (Montenegro, Yugoslavia), from rivermouth of Zeta to Skadarsko jezero lake. Hydrological analysis, level of water pollution are also presented, together with proposed water quality protection measures regarding the Yugoslav federal regulations for surface waters.

This paper points out the role and significance of civil engineering in dealing with the problems related to the water environment. Examples presented consider hydraulic structures and their impact on the aeration level in the watercourse. Aeration and reaeration have the most important effect on the oxygen water quality parameters and therefore on the entire living world in the particular ecosystem.

The last decade of 20th century in Serbia (Yugoslavia) was marked with economy recession, war surroundings, and finally bombing in the period March-June 1999. Global increment of environmental pollution was one of the catastrophic consequences. War actions caused destroying of big oil refineries and reservoirs, chemical complexes and industrial objects. Afterwards, toxic and carcinogenic substances reached out to atmosphere, soil and hydrographic system. Also, ammunition with depleted uranium was used. Heavy metals are very dangerous, so that, in this paper are presented results of investigation of heavy metals contents in surface soil layers. Heavy metals are movable, by erosion processes, with possibility of reaching hydrographic network and water supply systems. Investigation was carried out at a few localities: Fruska Gora, Ivanovo, Goc and Crni Vrh. Total contents of heavy metals (Zn, Cu, Pb, Cd, Mn) was determined by AAS (atomic spectrophotometry), by usage "Varian-Spectra AA-10" apparatus.

Aerobic bioremediation of oil contaminated soil was investigated on laboratory-scale for purpose of pilot-plant installation. Mineral oil was analysed using IR spectroscopy. Sediment was qualitative analysed on GC/MS. Research also included microbiological analysis.

The balance of production and respiration processes in water of Crnojevica river (Montenegro, Yugoslavia) has been estimate, over the estimate correlation between significant parameters of water quality (BOD, % saturation of O2, pH). Correlation between these parameters is established. The balances exist in stationary conditions. But, impact of precipitation is disturbing this state. The hydrodynamic conditions at underground flow and wastewater effluent from the town Cetinje area, has been influence for it, too. The data are referring to small and middle water state.

In order to determinate the concentration of elements: K, Ca, Na, Mg, Cu, Pb, Cr, and Cd in sea water and seagrasses Posidonia oceanica and Cymodocea nodosa sampling were done in the area of the Boka Kotorska Bay (Adriatic sea, Montenegro (Yugoslavia)). For majority of these elements variability of contents in the samples was great, but in the range of expectations. The concentrations of Pb and Cr in the seagrasses were higher from values in literature. Because of bioaccumulation and biomagnification of these metals, we have to investigate causes of these higher concentrations and possibility of toxic effects on the seagrasses and other organisms.

Water quality is a main precondition for use in water supply and bottling. In this paper, a review of Yugoslavian standard referring to maximum allowed concentration of some components, as well as a review of some components contents in prohibited concentrations in Yugoslav and foreign bottling drinking and mineral waters are presented.

In this paper are presented the length and weight growth of carp (Cyprinus carpio L.) from artificial lake Slatino (The Former Yugoslav Republic of Macedonia). Artificial lake Slatino because some recontruction works was whole emplied in 1993. Than all fish population was leaved in the river Mramorechka. Artificial lake Slatino has been stocking with individuals of carp (Cyprinus carpio L.) catch from Lake Ohrid. They are used for reproduction and in first years were used for reparation of the fish fond in artificial lake.