Nous proposons un modèle à générations imbriquées dans lequel les émissions polluantes des firmes sont régulées par un système de permis de pollution. Le quota global d'émission est imposé à l'économie et s'accompagne de contraintes politiques quant à son utilisation. Dans ce contexte, la question se pose de savoir si la régulation de la pollution par les permis et la réalisation de l'optimum de premier rang sont compatibles. Nous montrons que quand la politique est contrainte, il est possible d'établir l'optimalité de l'équilibre grâce à une politique de redistribution de la rente environnementale et à une politique de discrimination par les prix des intervenants (firmes et ménages) sur le marché des permis.

Nous proposons un modèle à générations imbriquées dans lequel les émissions polluantes des firmes sont régulées par un système de permis de pollution. Le quota global d'émission est imposé à l'économie et s'accompagne de contraintes politiques quant à son utilisation. Dans ce contexte, la question se pose de savoir si la régulation de la pollution par les permis et la réalisation de l'optimum de premier rang sont compatibles. Nous montrons que quand la politique est contrainte, il est possible d'établir l'optimalité de l'équilibre grâce à une politique de redistribution de la rente environnementale et à une politique de discrimination par les prix des intervenants (firmes et ménages) sur le marché des permis.

This paper presents the results of investigation on photosynthetic pigments, chlorophyll a in the river Danube (Serbia) during 2002-2005. Field investigations were carried out with seasonal dynamics on the river strech between 1112 and 851 km. Exceptionally in September, during low water period, investigations were carried out on the river strech between km 1260 - 851, including the main tributaries: Tisza, Sava, Velika Morava and Pek. The concentrations of chlorophyll a and phaeophytin a were determined using the standard ISO 10260/92 methodology, variant B. Pigment extraction was done in hot ethanol immediately after sampling, on board of a research ship. The results revealed seasonal concentration dynamics of the mentioned indicators of primary productivity and physiological status of the algae community where fall of chlorophyll a from the upstream towards downstream profiles was evidenced.

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.

The paper considers legal framework for the surface waters quality control as per our Regulation and Directive 75/440/EEC in terms of required quality of surface waters intended to be used for the drinking water production. Research has been done in eight accumulations designed for water supply in Serbia, and water quality index has been determined using WQI method during the period 2000-2004. The water quality in these accumulations was within the treshold values in relation to the required quality.

Microbiological and saprobiological characteristics of river Moraca and Skadar lake for period of 2004/2005 are done at localities: Pernica, Moraca estuary and Vranjina (Skadar Lake). The objective of the research is to establish quality of water of these aquatic ecosystems based on microbiological and saprobiological analyses, as well as, to show need for protection of these water ecosystems from permanent contaminations, mainly by sewage should be pointed out. Saprobiological index is determined based on Gulyas Pal, and Pantle Buck is used to determine saprobiological level.

The puddles Slatina and Pecena Slatina are the old meanders of the river Tamis. These ecosystems are periodicity fill with moderate salt and high alkaline water. The paper gives a review of qualitative and quantitative analysis of the algal compositions. Cyanoprokaryota and Euglenophyta are more common. All investigated parameters like compositions of lagal communities, their abundace, biomass and chlorphyll-a showed a high level of nature eutriphication in these ecosystems.

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.