This work is based on biotests being experimented at sea organisms - fish Serranus scriba. We were studying the activity of the mentioned fish in sublethal concentrations of organochloric pesticide - lindane. Besides the classic biotests, we used some new methods for neurotoxic testing that include the influence of this pesticide on circadian activity of fish as well as the variations in obtaining the positive conditioned reflexive responses. The results of these experiments show that this kind of fish reacts at the subtile changes of toxic concentration with the change of quality and rhythm in its conditioned reflexive reactions, that appeared earlier than other global signs of intoxication.

In this paper, we are consider processing of soils erosion and his way on protection expoitation of water for population water supply, melioration's systems for irrigation and for strew of manger of the Lim river with the tug and suspend bank (Montenegro, Yugoslavia). We are given suggestions for protective utilization of agricultural and forest lands and the possibilities of water exploitation from Bistrica river (Montenegro, Yugoslavia). That is useful for fishing, irrigation, energetic, tourism and water supply. In this paper, you can meet some suggestions about exploitations of minerals and organic fertilizars that are not toxics and they not any influence on pollution of land and water.

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.

Various physical, chemical and biological methods are used in complex investigations which are aimed at determining the quality of water. One of the oldest but also most widely accepted biological mathods is determination of saprobity on the basis of bioindicators. In application of these methods the existing lists of the indicators are most frequently used (Sladacek 1973, SEV 1977). In these lists only nine types of red algae (Rhodophyta) are specified as indicators of water quality. One of the main trends in development of algaeology in Serbia (Yugoslavia) is investigation of autoecological properties of algae and making a list of water quality indicator algae suited to the specific ecological conditions in water ecosystems of Serbia (Yugoslavia). The objective of this paper is to present information about apperance of red algae in the rivers of Serbia (Yugoslavia) and influence of physico-chemical factors upon their development, which represents a contribution to making of the above mentioned list of the water quality indicator algae.

On the basis of the enzymatic (phosphatase) activity and microbiological analysis as well, the influence of the oil refinery "Vital" - Vrbas (Serbia, Yugoslavia) wastewater to the recipient DTD (Danube-Tisza-Danube) canal water from the microbiological point of view was determined. In addition the efficiency of the factory's waste water purification plant was estimated. The obtained results of the complex microbiological-enzymological analyses indicated a good water quality at the point where the refinery's water supplies plant is situated (site 1). Very low water quality was determined downstream (site 4) and upstream (site 2) from the inflow of the refinery's wastewater's inflow. The later results might indicated the influence of an unknown pollutant in the region. However, the obtained O/H index value suggests that the self-purification ability of the canal waters is still preserved.

The paper presents one of the methods for calculation of temperature of a water course, downstream of the relase of a thermo-electric power-plant, taking into consideration the well-known temperatures and discharge values of the tributaries under different meteorological conditions. In view of the importance of temperature regime for the water eco-system, understanding the influence of the power plants on thermic capacity of the water course, is essential in design and use of the power plant. The author's intention is to help towards improving computer models for the computation of a water course thermic capacity. To this end a model developed at the Institute for Meteorology and Water Management in Poland and applied in many coutries has been presented.

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.