This paper analyzes the results on water quality in the Medjuvrsje water reservoir (Serbia, Yugoslavia) in the period 1994-1997. The water reservoir was erected for the needs of electric engineering in 1953 as far as 182 km along the Zapadna Morava river stream issuing from the Ovcarsko-Kablarska crag. All the tributaries of the Zapadna Morava flow in torrents, thereby depositing drift onto reservoir and inducing eutrophication process. Water regime in the water reservoir is conditioned by power plant operation, with daily oscillations about 30 cm causing turbulence in aquatic biota, including fish as the most developed aquatic vertebrate by their evolution level and greatest in biomass. Hydrochemical and some hydrobiological parameters influencing productivity of the water reservoir, were assessed. From hydrochemical aspect, this water reservoir contained water, the quality of which was found to be within 2nd-3rd class. The water was, however, loaded with high concentration of NH3, Fe, BPK5 and suspended substances inducing its quality to be out of the class range.

During the period 1990-1997, the content of 11 trace metals (Fe, Cr, Co, Al, Mn, Cd, Cu, Ni, Pb, Zn, Sr) was studied in muscle and other organs of fish from DTD (Danube-Tisza-Danube) channel system (Yugoslavia). According to obtained and analysed data, the trace metal bioaccumulation can possibly act as enviromental indicator in biomonitoring. DTD (Danube-Tisza-Danube) Channel System can, therefore, be classified as the 3rd class, concerning analysed trace metal content.

The determination of main and some biogenic and trace elements in the sea water of the Boka Kotorska Bay (Adriatic sea, Montenegro, Yugoslavia) was carried out by the atomic apsorption and emission spectrometric method (FAAS) and by the hydride technique AAS (HGAAS).

Biosystematic research of fish population from the river Nisava (Serbia, Yugoslavia) is placed from the mouth of Jerma river and Nisava river to the mouth of Nisava river and Juzna Morava river (Serbia, Yugoslavia). The next part of the research is about determining the methodology for counting of particular fish species in the river Nisava. Hematological analyses of some species were done at the same time in order to establish the relation between water quality and number of erythrocytes, leucocytes and quantity of haemoglobin. Two autochthonous and allochthonous species were analyzed. The method used in this research are explained as well.

During the period from 11th May, 1991 to 5th March, 1994, seasonal study of the river Jablanica (Serbia, Yugoslavia) macrozoobenthos was carried out. Investigations were done of three sectors: in the upper, middle and down reach of the river, with the aim to estimate water quality changes by the changes in bottom fauna composition. Bottom fauna community was composed of 17 invertebrate groups with 100 taxa determined. The most diverse Oligochaeta (21 taxa) and Ephemeroptera (19 taxa). Macroinvertebrates diversity decreased downstream the river as a result of the pollutional degree increase. Saprobic indices were from 1.51 (sector 2) to 1.8 (sector 3).

The paper presents some procedures for identification of low flow required for taking preventive measures in the rivers with no comprehensive hydrological observations. Besides using time - space parameters, temparery or simultaneous hydrometric observations in the observed rivers are also recommended. The paper concludes with the presentation of relevant low flow calculation results for one river in Zlatibor region (Serbia, Yugoslavia), which has not been examined so far.

During the 1981-1996 period, qualitative and quantitative structure of oligachaeta communities as indicator of the eutrophication process was investigated in the lake Palic (the 2nd oxidation lake), Serbia (Yugoslavia). The mean annual number of oligochaetes was related to nutrient concentration (total nitrogen and total phosphorus). The analysed data for both oligochaete community and nutrients, leads to the conclusion that the second oxidation lake Palic can be classified as an highly eutrophic environment, with tendency towards dystrophic, particularly in past two years.

Competing ions strongly affect heavy metal sorption onto the solid surfaces of soil. This study evaluated competitive sorption of Cd, Cu, Ni, Pb and Zn on three soils: Calcixerollic Xerochrept, Paralithic Xerorthent and Lithic Haplumbrept. Monometal and competitive sorption isotherms were obtained at 25°C. The individual effect of ions on retention of the others was ascertained by a fractional factorial analysis design. Most of the sorption isotherms belonged to type L subtype 2 in the classification of Giles. In competitive sorption the initial linear part was shorter and the knee sharper when compared with monometal sorption isotherms. Parameters related to sorptive capacity, such as Point B, Langmuir monolayer and Freundlich distribution coefficient, were higher in monometal than in competitive sorption, and in basic soils than in acidic soil. Calcium desorbed at different points of the sorption isotherms indicated that cationic exchange with Ca was the main retention mechanism in calcareous soils. For Pb, the ratio Ca desorbed/Pb sorbed was close to one; for Cu, Ni and Zn the ratio ranged from 1.20 to 1.37, probably due to partial dissolution of calcium carbonates by hydrolytic processes during retention. On the other hand, Cd had a ratio around 0.6 reflecting another additional retention mechanism, probably surface complexation. Fractional factorial design confirmed that the presence of the cations investigated reduced the amount of the five metals retained, but the presence of Cu and Pb in the system depressed Ni, Cd and Zn sorption more than the inverse. Cation mobility was enhanced when equilibrium concentration increased and the effect was higher in Ca-saturated soils.

peer reviewed | A management of nitrogen fertilizers and a conversion of cropping soil into fallow were developed to reduce the nitrate pollution of spring exploit to supply with drinking water the southwestern Luxembourg. The methodological approach was based on in situ observations and includes a study of nitrates lost by leaching (measure of nitrogen profiles in experimental fields, use of vertical soil water cup ceramics) and study of the water quality of springs (measurements of nitrate concentrations). Since October 1995, the nitrate concentrations of polluted springs have been reduced by 25 mg l-1 due to the fallow and the reduction of nitrogen fertilizers.

The increased inorganic nitrogen (N) deposition in the last decades has become a major concern for the health of forests. In forest ecosystem, where N might no longer be limiting to primary production, the excess N is thought to be related to forest decline and a concept of ‘N saturation ‘ has been developed. In particular, N, in the form of NH4, in excess to plant and microbial demands could lead to soil acidification if nitrified in the soil and leached, causing loss of base cations or mobilisation of phytotoxic aluminium. As part of the CORE project (CEC), investigating nutrient dynamics in European coniferous forest soils, we studied the effects of continuously increased (NH4)2SO4 deposition and soil characteristics on Norway spruce (Picea abies [L.] Karst) and Scots pine (Pinus sylvestris L.) fine root biomass, vitality and chemistry with an ingrowth core technique. The same experiment was performed in a Norway spruce stand on clay soil (Grizedale, UK) and a Scots pine stand on sandy soil (Wekerom, NL), using soil from each of the two sites. Root-free ingrowth cores reproduced organic and mineral soil horizons to 15 cm depth. They were covered to exclude native throughfall and watered every 2 weeks with throughfall or throughfall with (NH4)2SO4 added to increase deposition by 75 kg ha-1 a-1 NH4+-N. The ingrowth cores were sampled after 19 months, divided into layers, roots washed and analysed for biomass, necromass, root length, root tip number (RTN), root tip vitality and fine root chemistry. A previous field experiment had shown high soil solution Al concentrations at both sites, and an increase in NO3- and Al concentrations in response to increased (NH4)2SO4 deposition at the Grizedale site. The effects of high (NH4)2SO4 deposition depended on tree species, soil type and soil horizon. For Norway spruce, (NH4)2SO4 deposition did not result in any significant changes in root growth or vitality when growing into the native clay soil. However, when growing into the sandy soil, RTN and the proportion of dead roots were increased by N deposition. Norway spruce fine root N content was also increased in the organic horizon of both soil types. For Scots pine, (NH4)2SO4 treatment caused increased fine root Al content and a decreased Mg/Al ratio in the mineral layer of the sandy soil, with opposite effects in the clay soil. This (NH4)2SO4 treatment effect in the sandy soil for Scots pine was the only indication of a potential adverse effect of (NH4)2SO4 deposition on fine roots. Further results demonstrated the dominant importance of inherent soil characteristics and the stratification into soil horizons on fine root growth and chemical composition. For example, a negative correlation between root biomass and fine root Al content was established for Norway spruce.