Muzeul Olteniei Craiova. Oltenia. Studii şi comunicări. Ştiinţele Naturii. Tom. 33, No. 2/2017 ISSN 1454-6914 153 CHARACTERIZATION OF WATERS AND SEDIMENTS FROM LACUSTRINE COMPLEX ADUNAȚII OF GEORMANE GAVRILESCU Elena, CIOBOIU Olivia, CISMAŞIU Carmen - Mădălina Abstract. The purpose of this paper is to evaluate the quality of water and sediment in Lacustrine Complex Adunații of Geormane under the influence of anthropogenic factors in order to understand the complex processes taking place in these habitats, in order to develop strategies for rehabilitation and conservation of the affected aquatic ecosystems. Seasonal samples of water and sediment were taken from various points of the lacustrine complex represented by Victoria Lake and Marica Pond, respectively the shore areas (the head and tail of the lacustrine ecosystems) and the central ones. A number of physicochemical and enzymatic analyses were made. Thus, the pH of the water of Victoria Lake was 8.24 to 8.54 units, fixed residue 322.7 g/l and chloride 87.2 g/l. The hardness of Victoria and Marica lakes varies between 10.66 degrees Ge and 18.74 degrees Ge. The eutrophic Victoria Lake has a chlorophyll content 8 to 25 μg/l. These are intended to highlight the functional diversity of the microbiota involved in biogeochemical cycles in these media (water, sediment). Enzymatic activity records large variations, depending on the nature of the studied enzyme, sampling point, environment, season, main pollutants of the lake, and physico-chemical characteristics of the water. Dehydrogenase activity of sediments shows relatively low seasonal fluctuations; the minimum value was 0.23 μg formazan / 1 g sludge (dry matter) and phosphatase activity is moderate in Marica pond, the minimum phosphatase being 73.5 μg phenol / g sludge. Victoria Lake has an intense catalase activity of 2.30 mg H 2 O 2 / g sludge. The knowledge of the intensity of the enzymatic activity represents a new method of research within the framework of water protection programs, which allows the characterization of the impurity degree of an aquatic ecosystem and offers the possibility to forecast the evolution in time, respectively quality maintaining. Keywords: lacustrine ecosystems, sediments, physico-chemical analyses, enzymes. Rezumat. Caracterizarea apelor și sedimentelor din Complexul Lacustru Adunaţii de Geormane. Scopul lucrării de faţă îl constituie evaluarea calităţii apei si sedimentului din Complexul Lacustru Adunaţii de Geormane sub influenţa factorilor antropici în vederea înţelegerii proceselor complexe care au loc în aceste habitate, în scopul elaborării unor strategii de reabilitare şi conservare a ecosistemelor acvatice afectate. Au fost prelevate sezonier probele de apă și sediment din diferite puncte ale coplexului lacustru reprezentat de lacul Victoria și balta Marica, respectiv zonele litorale (capul și coada ecosistemelor lacustre) și centrale. Au fost determinate o serie de analize fizico-chimice si enzimatice. Astfel, pH-ul în apa lacului Victoria a fost de 8,24 - 8,54 unități, reziduu fix 322,7 g/l şi clorurile 87,2 g/l. Duritatea în cazul lacurilor Victoria și Marica variază între 10,66 grade Ge și 18,74 grade Ge. Lacul eutrof Victoria are un conţinut de clorofilă a cuprins între 8 – 25 μg/l. Acestea au rolul de a evidenţia diversitatea funcţională a microbiotei implicate în ciclurile biogeochimice din aceste medii (apă, sediment). Activitatea enzimatică înregistrează variaţii mari, dependente de natura enzimei studiate, de punctul de prelevare a probelor, de mediu, de anotimp, de principalii poluanţi ai lacului, cât şi de caracteristicile fizico-chimice ale apei. Activitatea dehidrogenazică a sedimentelor prezintă fluctuaţii sezoniere relativ scăzute, valoarea minimă înregistrată a fost de 0,23 μg formazan / 1 g nămol (substanţă uscată), iar activitatea fosfatazică este moderată în balta Marica, valoarea minimă a fosfatazei fiind de 73,5 μg fenol / g nămol. Lacul Victoria prezintă o activitate catalazică intensă de 2,30 mg H 2 O 2 / g nămol. Cunoaşterea intensităţii activităţii enzimatice reprezintă o nouă metodă de cercetare în cadrul programelor de protecţie a apelor, acestea permiţând caracterizarea gradului de impuritate al unui ecosistem acvatic și posibilitatea de a prognoza evoluţia în timp, respectiv menţinerea calităţii. Keywords: ecosisteme lacustre, sedimente, analize fizico-chimice, enzime. INTRODUCTION The protected area of national interest Lacustrine Complex Adunații of Geormane (code: 2393) is located in a plain area within the hydrographical basin of the Jiu River and it extends to the territory of Bratovoeşti and Teasc settlements, being part of the wetland category. This zone is characterized by the presence of lake ecosystems, such as Marica Pond and Victoria Lake, which have adjacent wetlands. Victoria Lake is located on the upper left terrace of the Jiu, called Rojiştea terrace, at about 25 km south of Craiova, in Oltenia Plain. This lake forms an isolated biological unit linked to the Jiu through a canal for the surplus water discharge through Marica Pond (MARX, 1982) (Fig. 1). The soils in this Protected Natural Area of National Interest are sandy, with a low humus content, which makes them vulnerable to erosion caused by surface water. In order to prevent or reduce erosion effect of the shores, it is recommended to plant native tree species to maintain their integrity. The clogging of Marica Pond and Victoria Lake is closely related to erosion and natural eutrophication. Thus, by their combined actions, they can contribute to the increase of the sediment load of the lakes; they can favor the excessive development of the vegetation and can lead to the reduction of the surface of the water. Natural eutrophication occurs as a result of their organic load and is particularly evident during summer, when high nutrient concentrations in water also increase. The accumulation of organic mass, increased amounts of nutrients such as nitrogen and phosphorus, lead to the abundant development of various microorganisms, which consume large amounts of oxygen in the water.