Albanian j. agric. sci. 2013;12 (1): 25-31 Agricultural University of Tirana Correspondence: Aida Bani, Agricultural University of Tirana; Email: aida_alushi@hotmail.com (Accepted for publication 13 January 2013) ISSN: 2218-2020, © Agricultural University of Tirana RESEARCH ARTICLE (Open Access) Risk assessment of Butrinti lagoon: spatial and temporal distribution of heavy metals in different pools TEUTA TOPI 1,2 AIDA BANI 1* , SULEJMAN SULÇE 1 1 Agro-Environmental Department, Faculty of Agronomy and Environment, Agricultural University of Tirana, Koder-Kamez, Tirane, Albania 2 Ministry of Agriculture, Food and Consumer Protection, Tiranë, Albania Abstract Heavy metals enter in lagoons from pedo-geological background as well as from man-made sources through several pathways. Heavy metals released into the water are eventually accumulated in the sediments and in the lagoon’s aquatic organisms, especially in mussels, which act as recorders of heavy metals pollution event. This study aims to contribute in (i) quantifying the origin and degree of heavy metals pollution in the sediments, water lagoon and mussels, (ii) exploring the concentrations of heavy metals in mussels widely cultivated in this Lagoon. The water samples were taken at the surface and bottom of the lake between May 2010 and January 2011. The results showed that the concentrations of Cd (2.9 mg kg -1 ) were higher in soils formed over lime in the north of the Lagoon. Hg was nearly 234.89 µg kg -1 , which is also considered of medium values for these types of soil. The maximum values of Cr content were 237.38 mg kg -1 , or much higher than the average of soils over lime in Albania. The highest concentrations in sediment samples (mg kg -1 ) for Pb (346), Cd (4.14), Cr (171.9) and Hg (36.4) were found in the eastern and southern area of the Lagoon where there have been intensive agricultural activities. The results showed that the concentration (µg L -1 ) of Pb (10.78) at the lake bottom in May was higher than at the surface of water but it was generally low when compared to the WHO standard. On the other hand Cr was high with mean values of 56.6 µg L -1 at the bottom of the lake water in August. The data also indicated that mussels’samples which was collected in May in the southern area of the Lagoon showed higher levels (mg kg -1 ) of Pb (0.49) and Hg (0.14). However, the highest concentrations of Cd (0.36), Cr (0.50) were recorded in August. There is a correlation between the heavy metals and their sources. We hold that some precautions should be taken against the heavy metal pollution around Butrinti Lake considering the ecological, agricultural and economic importance of this area. Keywords: Heavy metals, pollution, Butrinti Lagoon, mussels. 1. Introduction Butrinti lagoon (16 km 2 ) is one of the most interesting lagoons of tectonic origin. It is connected to Bufi Lake by a communicating channel of a flow of 3 m 3 sec -1 , and also to the Ionian Sea by a 3 km long canal. During the past few decades, the lagoon has been used intensively in the aquaculture of mussels (Mytilus galloprovincialis) (up 4500 ton gross product/year-2009 and still 85 000 tons - 1988) [1] The main anthropogenic pressure in Butrinti lagoon is represented by agricultural activities, tourism and urban development, while mussel farming represents one of the main economic activities in the region. Heavy metals enter into the Lagoon environment from natural as well as man-made sources through several pathways, e.g. weathering processes reaching aquifers mainly through subterranean waters and runoff, atmospheric depositions, point as well as non point pollution sources. Heavy metals released into the water eventually accumulate in the sediments, which act as recorders of heavy metal pollution event [2, 3]. Although heavy metals enter in the Mediterranean Sea from natural sources, e.g. pedo-geochemical background [4], industrialization and human activities ha have caused an increase in the emission of heavy metals into the marine environment in the last decades resulting in polluted hot spots near urbanized coastal and transitional water areas [5, 6]. The main land- based pollution sources are in the Albanian coastal area, including lagoons, urban, agricultural and industrial effluents [3]. The assessment of heavy metals is directly related to the food chain as the primary product in the Lagoon are the mussels which are fixed on a lot of installations (73) and have a productivity of 4500 tons a year. The passing of heavy metals form sediment to mussels becomes evident in conditions of high temperatures that cause high mineralization coefficients. The aim of the present work was to contribute in quantifying the temporal, spatial distribution of the heavy metals and the degree of heavy metal, and explore the role of heavy metals