1. 1. INTRODUCTION T he Iberian Pyrite Belt (IPB) is a part of the South Zone of the Hercynian Iberian Massif (SW of Iberian Peninsula), being pyrite (FeS 2 ) the main mineral associated to this volcano-sedimentary complex. The intensive mining activities in the area, which started in the Roman Empire, have generated mine pits where underground and/or rainwater are stored. T hese stored waters have produced oxidation of pyrite and, consequently, the pH of pit water has become acid (pH around 2), causing the dissolution of metals and natural radionuclides. N owadays new mining projects are being implemented in this zone. T he main objective of this work is to show and discuss the levels found for different natural radionuclides (mainly uranium isotopes and daughters via α-sectrometry) in water samples and sediments collected from several mine pit lakes located in the south-west of Spain. Pit lake water R esults of activity concentration of Th-isotopes and 210 Po in pit lake water collected in 2012 in former mining facilities. Pit lake sediments F ormer mining facilities have been studied and levels of natural radionuclides (U-isotopes, Th-isotopes and 210 Po) have been determined. Water, sediment and sulfate efflorescent salts samples were analyzed in this work. The levels of U-isotopes in water have a wide range depending on the facility. However the activity concentrations in sediment s are similar in three of studied facilities (about 5 Bq/kg). Acid pH of pit lake water causes the mobility of actinides from sediment to water. S urface waters (the Odiel River, its tributaries and low-flow AMD’s) have been also studied. In these cases, only U- isotopes show a clear radioactive impact of facilities on the neighboring environment. H eavy metal concentrations have been determined by ICP-MS in water samples. A same pattern, in the case of Fe, Cu, Zn, U and Th, with low concentrations in the Odiel River and higher concentrations in AMD’s, has been clearly observed. w ater samples were acidulated just after they were collected and stored in plastic bottles. Once in the laboratory, a 1 liter aliquot was separated for analysis. T he first step of analysis was the addition of well known activity of tracers ( 232 U, 229 Th and 209 Po) to obtain the radiochemical yield of the process. Actinides and polonium separation was obtained by co- precipitation with iron hydroxide. I n the case of water samples, firstly 10 mg of Fe 3+ were added into the aliquot and pH is adjusted to 8-9 with ammonia. The precipitate is separated by centrifugation. Once dried, the precipitate is dissolved with HNO 3 8M. S ediment and sulfate efflorescent salts samples pretreatment was an atmospheric digestion using aqua regia, H 2 O 2 and HNO 3. Actinides and polonium were co-precipitated with iron hydroxide. F or both types of samples, U-isotopes, Th-isotopes and polonium were separated by solvent extraction with TBP. Alternatively a UTEVA chromatographic resin was used for isotope separation. R adioactivity sources were obtained by autodeposition on a silver disc, in the case of polonium, or by electrodeposition on stainless steel disc, in the case of uranium or thorium. R adioisotope activity was determined by alpha-spectrometry using Alpha Analyst with PIPS detectors. G amma-ray spectrometry was made using two detectors (Xtra and REGe) with a typical electronic associated. Spectra treatment was made using a Genie 2000 software. NORM levels in Spanish pit lakes and their impact on neighboring environments Guillermo Manjón*, José Antonio Galván, Juan Mantero, Inmaculada Díaz, Rafael García-Tenorio Grupo de Física Nuclear Aplicada. Universidad de Sevilla, Spain Centro Nacional de Aceleradores, Sevilla, Spain 2. EXPERIMENTAL 5. RESULTS: IMPACT ON NEIGHBORING ENVIRONMENT 6. CONCLUSIONS P it lakes in former mines located in the IPB have been studied in this work. In the Figure pit lake of San Telmo mine nowadays. *Author for correspondence: Guillermo Manjón. Universidad de Sevilla. ETS Arquitectura. Departamento de Física Aplicada 2. Av. Reina Mercedes 2. 41080 Sevilla, Spain. E-mail: manjon@us.es M ap where have been remarked the sites of sampling along Odiel River. Pit lakes sampled in 2012 and surface water sampled in 2013. Samples a and b were sampled in 2009. MINES 238 U 234 U/ 238 U CONCEPCIÓN14±3mBq/ℓ2,79±0,70 CONFESIONARIOS247±18mBq/ℓ4,48±0,37 SAN TELMO219±11mBq/ℓ2,28±0,14 LA ZARZA1094±20mBq/ℓ1,60±0,04 MINES 238 U 234 U/ 238 U CONCEPCIÓN5,55±0,77Bq/kg2,59±0,43 CONFESIONARIOS0,74±0,14Bq/kg4,62±0,95 SAN TELMO4,95±0,3Bq/kg2,22±0,16 LA ZARZA5,1±0,56Bq/kg1,90±0,26 R esults of activity concentration in pit lake sediments collected in 2012 in former mining facilities. Measured by α-spectrometry. Pit lake sulfate efflorescent salts MINES 238 U 234 U/ 238 U CONCEPCIÓN17,53±1,22Bq/kg1,97±0,17 CONFESIONARIOS6,08±0,43Bq/kg4,63±0,33 SAN TELMO14,58±0,15Bq/kg3,16±0,04 LA ZARZA13,58±0,79Bq/kg1,59±0,09 R esults of activity concentration in pit lake sulfate efflorescent salts (FeSO 4 ·7H 2 O) collected in 2012 in former mining facilities. Measured by α-spectrometry. CODESITEKIND OF SAMPLE 238 U (mBq/ℓ) 234 U/ 238 U aNOT CONTAMINATEDODIEL RIVER2,1±0,21,41±0,18 bNOT CONTAMINATEDODIEL RIVER1,8±0,21,42±0,17 1NOT CONTAMINATEDODIEL RIVER3,7±0,71,24±0,32 2BEFORE AMD LA ESPERANZAODIEL RIVER4±11,75±0,50 3AFTER AMD LA ESPERANZAODIEL RIVER6±11,50±0,30 4BEFORE AMD PALOMINOODIEL RIVER4±12,25±0,75 5AFTER AMD PALOMINOODIEL RIVER5±11,68±0,38 6BEFORE AMD AGRIOODIEL RIVER4,1±0,21,85±0,12 7AFTER AMD AGRIOODIEL RIVER133±101,55±0,15 CODESITEKIND OF SAMPLE 238 U (mBq/ℓ) 234 U/ 238 U 8MINE LA ESPERANZAAMD102±52,14±0,14 9MINE LA ESPERANZARECYCLING POOL258±61,26±0,04 10PALOMINO CREEKAMD152±81,58±0,11 11AGRIO CREEKAMD1117±291,54±0,06 3. SAMPLING I CP-MS technic has been applied to the determination of heavy metal concentrations. In this figure U concentrations determined by ICP-MS and α-spectrometry are compared. 4. RESULTS: PIT LAKES C oncentration of most abundant heavy metals in surface waters determined by ICP-MS. The number of site corresponds to Table and Map. C oncentration of 238 U in surface water (Odiel River, tributaries and AMD’s). 210 Po activity concentration was also measured and levels can be considered not affected by mining activities. AMD means “Acid Mining Drainage”. MINES 234 U (mBq/ℓ) 230 Th (mBq/ℓ ) 210 Po (mBq/ℓ) 232 Th (mBq/ℓ) CONCEPCIÓN 39 ± 514 ± 3 < 0.5 18 ± 3 CONFESIONARIOS 1100 ± 43133 ± 813± 157 ± 4 SAN TELMO 500 ± 17171 ± 10 < 6 39 ± 6 LA ZARZA1750 ± 30390 ± 2033 ± 4122 ± 12 R esults of activity concentration of U-isotopes and 234 U/ 238 U activity ratio in pit lake water collected in 2012 in former mining facilities.