N° d’ordre : 03 /2011-D/S.T RÉPUBLIQUE ALGÉRIENNE DÉMOCRATIQUE ET POPULAIRE MINISTÈRE DE L’ENSEIGNEMENT SUPÉRIEUR ET DE LA RECHERCHE SCIENTIFIQUE UNIVERSITÉ DES SCIENCES ET DE LA TECHNOLOGIE « HOUARI BOUMEDIENE » FACULTE DES SCIENCES DE LA TERRE, DE GEOGRAPHIE ET DE L’AMENAGEMENT DU TERRITOIRE THÈSE Présentée pour l’obtention du grade de DOCTORAT EN : SCIENCES DE LA TERRE Spécialité : Hydrogéologie Par : ALLIGUI Fadila Sujet : Dispersion Géochimique Naturelle et Artificielle du Mercure dans la Région de Azzaba -W.Skikda- et son Impact sur l’Environneent. Soutenue publiquement le 7 Juillet 2011, devant le jury composé de : M. AISSA Djamel Eddine Professeur à l’USTHB Président M. BOUTALEB Abdelhak Professeur à l’USTHB Directeur de Thèse M. BOUDOUKHA Abderrahmane Professeur à l’Université de Batna Examinateur M. SAIGHI Omar Professeur à l’USTHB Examinateur M. MIMOUNI Omar Maître de Conférences/ A, à Examinateur l’USTHB Mme. NEZZAL Fatiha Maître de Conférences/ A, à Examinateur USTHB Ordr N° : 03 /2011-D/S.T PEOPLE’S DEMOCRATIC REPUBLIC OF ALGERIA MINISTRY OF HIGHER EDUCATION AND SCIENTIFIC RESEARCH UNIVERSITY OF SCIENCES AND TECHNOLOGY « HOUARI BOUMEDIENE » FACULTY OF EARTH SCIENCES, GEOGRAPHY AND LAND USE PLANNING THESIS Submitted in partial fulfillment of the requirements for the degree of DOCTOR By: Alligui Fadila Geochemical Natural and Artificial Dispersion of Mercury in Azzaba - Skikda Province and its Impact on Environment Defended on July 7, 2011. The jury is composed of: Mr. AISSA Djamel Eddine Professor (FSTGAT/USTHB) Chairman Mr. BOUTALEB Abdelhak Professor (FSTGAT/USTHB) Supervisor Mr. BOUDOUKHA Abderrahmane Professor (University of Batna) Member Mr. SAIGHI Omar Professor (FSTGAT/USTHB) Member Mr. MIMOUNI Omar Doctor (FSTGAT/USTHB) Member Mrs. NEZZAL Fatiha Doctor (FSTGAT/USTHB) Member 1 ACKNOWLEDGEMENTS I would like to express my deep gratitude to my supervisor Prof. Boutaleb Abdelhak for his intellectual support and able guidance throughout the whole project especially during the difficult times. I cannot simply thank him enough for all the trust he put in me. Sincere thanks to the examination committee for their useful discussion and critical comments which enriched this work. I would like to say thanks to Prof. Aissa Djamel Eddine for his support and I extend my thanks to Dr. Chibane Ibrahim for his encouragement and critiques. Many thanks should also go to Ms. Samia Bouzid from the ANCGM, Mr. Yassine Aissaoui from ENOF; Dr. Taleb Mourad, Dr. Rouabhi Abderezzak, Mr Rouabhi Djamel, Mr. Mermoul Houssem and Mr. Mermoul Mohamed Lamine for constant help during the months of field work and sampling. I would like to say big thanks to Mr. Hocine Zenati, Ms. Mihoubi Dhaouia, Ms. Soltani Mounira, Mr. Bouhadad Noureddine and Mr. Ferdi Abdelhak at the National Hydraulic Resources Agency of Constantine (NHRA) for the arrangement of soils, sediment and water samples analysis. Mr. Tachetache and Mrs. Kadouri from ONM, Ms. Bellara from DHW-Skikda also provided me with useful hydrologic, hydrogeologic and climatic informations. I also appreciate the instructive discussions with Prof. John Stewart and Dr.Ulrich Ofterdinger from Queen's University in Belfast (U.K) during my stay in their laboratories. Thanks are also extended to the staff of the Water and Environment Research and Study Center in the University of Jordan for receiving me in their laboratories and providing me with useful assistance in analysis protocols and their applications. I wish to thank my family, near and far, for all the emotional support and encouragement. I ABSTRACT Mercury has a number of unique properties that make it a valuable metal in industry, but which has lost its importance in industrial processes due to its harmful effect on environment as well as on human health. In fact, in Azzaba district alone, 99339 of residents (according to 1998 census results) live in very close contact with the natural environment of mercury mineralization and mining wastes, and obtain their food and drinking water directly from the mined area and its vicinity. The local residents rely heavily on locally grown crops within the mined area as well as in areas containing known deposits not yet mined. The geochemical pathways of mercury therefore affect the local populations more directly and also present an opportunity to investigate the role of mercury and associated toxic metals to human health risks. This thesis presents a compilation of known background knowledge for mercury in Azzaba district rocks, soils and waters; it focuses on natural accumulation of mercury associated with As-Hg-Pb-Zn mineralization in Azzaba in southwest Skikda Province East of Algeria, as a case study for mercury hazard in a geo-environmental perspective. It aims at understanding of the occurrence, the transfer processes and the environmental impacts of mercury related to natural processes and human activity. The distribution and dispersion of mercury together with lead and arsenic in bedrock, sulfide ore, soil, sediment, ground and surface waters, crops and vegetation have been examined through this study and from other works in the region. Preliminary compilation of mercury analyses from different environmental compartments throughout Azzaba clearly demonstrates that more attention needs to be given to this element. Due to locally and regionally occurring Hg-rich rocks, natural enrichment is observed, often exceeding recommended limiting values. This has to be taken into account when judging anomalies of this element in soils and waters. The natural or anthropogenic origin of a given mercury anomaly can only be determined by a careful environmental survey that includes the geological context. This study shows that Azzaba can be characterized as a specific geological context of mercury lead, copper and arsenic accumulations. The extensive occurrences of sulfide minerals, such as cinnabar, galena, sphalerite, arsenopyrite and pyrite are the primary carriers of Hg, Pb, Fe, Zn and As in the rocks and ores. II After Bikmeev 1970 Clays and sandstones of the Oligocene present an Hg, Pb, Zn geochemical background contents of respectively 0.6 ppm, 30 ppm, and 60 ppm; on the other hand, the Copper content is relatively high (80 ppm). As for limestones and carbonated sandstones of the belt, the Hg background contents range from 0.2 to 1.5 ppm; the Cu, Pb and Zn contents are high as well. For groundwaters, the result of this study shows that shallow groundwaters typically contain more than 10 µg/l to 340 µg/l of Hg. The waters from the Ghenicha open pit lake exhibit exceptionally high values of mercury, lead and copper with respectively 40 µg/l, 69 µg/l and 3820 µg/l due to the presence of natural dispersed Hg- mineralisation. For surface waters, the few data available all come from Fendek stream and its tributaries. The values adjacent to the industrialized area are expectedly high in the range of 0.13 µg/l to 900.6 µg/l, the concentration from the processing water reached 3040 µg/l. The dispersion of mercury together with lead, copper and arsenic in the specific ecosystem of Azzaba is constrained by the original As-Hg-Pb-Zn-As sulfide mineralization, the specific topography and hydro-geomorphology, and by the disturbance of human activity. High values of mercury are concentrated in the mineralized and mining area; away from this area, mercury concentrations decreases gradually to a background level. Mercury from bedrocks is accumulated in soils, sediments and waters within Azzaba catchement area. The recognition of natural sources and the definition of specific geochemical baselines for toxic metals have been used to help discriminate the relative contributions of mercury due to past and present mining versus natural processes. High geochemical baseline concentrations in outcropped rocks and in soils indicate that both the natural erosion and leaching of outcropped host rocks and soils associated with Hg mineralized area and the mining activities contribute to the high mercury accumulations in arable soils and in the aqueous system. Mercury accumulates in all plant species. But the rate of accumulation of this element depends on the nature of the species (Casuarina equisetifolia does not accumulate in the same way as Cupressus sempervirens), on growth cycle (see herbaceous species and tree species), on time exposure and distance and from source of pollution and climatic conditions and topography (as and as the distance from the pollution source, the rate of Hg accumulated decreases, however, this change over source, and depending on the influence of prevailing winds and the presence or absence of natural III screens can play the role of pollution breeze.. The mercury accumulation by lichen transplants perfectly conveys the importance of pollution of the region Azzaba with a maximum accumulation of 0.41 µg/g to 0.5 km to the east and 2 km north east of the (Alioua, 2008). The pathways of Hg into the human body are mainly through the food chain, and dermal and inhalation exposures which are less pronounced. Due to high uptake of Hg by crops, the principal pathway of mercury into the food chain is through the consumption of crops grown in contaminated soils. The daily uptake content of Hg through consumption of locally planted Hg rich crops is estimated to be around 0.150 mg, which is 150 times more than the daily ingestion in mercury-free background areas. Hg levels in drinking water are above the safe drinking limit, and poses risk to human health under current conditions. Hg, Pb, Zn and As play significant role in the health problems of the Azzaba area. The socio-economic conditions in the Azzaba enhance the environmental impact of mercuty in the ecosystem. Nutritional deficiency, rather than the climatic factor, combined with exposure to high Hg contents in soils and crops is capable of causing mercury toxicities that prevailed in the present days. In order to alleviate the problem or the reoccurrence of a major problem, the local population should be made aware of mercury hazard and of some of the easily applicable steps to reduce the dispersion of mercury.