Technical paper Chemical Composition of Natural Sea Salt from the Sečovlje Salina (Gulf of Trieste, northern Adriatic) Nives Kovač,1* Neli Glavas,1 Matej Dolenec,2 Nastja Rogan Smuc2 v 3 and Zdenka Slejkovec3 1 Marine Biology Station, National Institute of Biology, Fornače 41, 6330 Piran, Slovenia 2 University of Ljubljana, Faculty of Natural Sciences and Engineering, Department of Geology, Aškerčeva 12, Ljubljana, Slovenia 3 Department of Environmental Sciences, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia * Corresponding author: E-mail: kovac@mbss.org Received: 11-01-2013 Abstract In our research the concentrations of major and minor elements were determined in natural sea salts from the Sečovlje salina (Piran salts, Slovenia) and compared to those of selected samples of commercially available unrefined salts with different geographical origins (Croatia, Austria, Italy, Portugal, India, and Pakistan). In the case of major element contents such as sodium (Na), iron (Fe), aluminum (Al), manganese (Mn), and titanium (Ti) many similarities were observed among the analysed salt samples. On the other hand, Piran salts are characterized by lower silicon (Si) values. Among the salts from the Sečovlje salina, the salt with the trade name Piran salt has a higher Mg content while Flower of salt has a lower concentration of calcium (Ca). In Slovenian samples the majority of trace element values were lower than 0.5 |g g-1, which was comparable to the results from commercially available unrefined salts. The salt composition differences observed indicate area-specific signatures related to geographic origin and diverse salt production processes. The quality of the studied salt samples is in accordance with standards established by the Codex Alimentarius Commission and the Piran salts are also suitable regarding issues of national food control. Keywords: northern Adriatic Sea, Sečovlje salina, microbial mat-petola, natural salt, elemental composition 1. Introduction Sodium chloride or common salt, table salt, or halite is a white crystalline chemical compound with the chemical formula NaCl that is usually observed in a cubic or, rarely, an octahedral crystal form. It is an abundant mineral that is employed for industrial (manufacturing different chemicals), agricultural, and water-conditioning uses as well as a de-icer. Salt is also commonly used in the food industry as a flavour enhancer and it is important as a daily diet requirement of humans. The chemical industry represents the largest consumer of salt (56%) followed by human consumption (22%), road de-icing (12%) and other users (10%).1 Salt can be obtained from surface or underground mining of halite deposits (usually former sea beds; underground and surface rock salt) or from solar evaporation of seawater or inland brine. Recently world-wide salt production was estimated to be about 260 million tons per year, of which 100 million t/y was solar salt and 80 million tons rock salt and salt produced from brine.1 Salt for human consumption is produced in different forms: salt evaporated as well as cold refined, rock salt, sea salt (refined and unrefined), dendritic (contains ferroc-yanide salts), fluoridated salt, and salt fortified with iron. Refined salt usually contains about 99.5-99.9% NaCl and some additives such as whitening and anti-caking agents to keep the salt crystals from sticking together as they absorb moisture from the air (such as ferrocyanide salts, sodium silicoaluminate, magnesium carbonate...). All salts can be iodized, fluoridated and fortified with iron. "Natural" sea salt (unrefined) is not altered by man so contains no additives against caking and is not chemically processed. The salt is naturally evaporated by the sun and wind allowing the sea salt to retain its natural mineral content. The most important thing to remember at this point is that some elements (some trace heavy metals) are significant nutritionally, either for their essential nature or their toxi-city. Elemental salt composition is closely related to salt production techiques and environmental factors. Precipitated salt crystals may contain some organic and inorganic composites (soluble and insoluble). Soluble fractions mainly originate in the mother brine. While the salt crystals grow, small quantities of brine can be trapped within the salt structure. Such fluid inclusions are mostly inorganic with dissolved chemical elements filling inter- and in-tra-crystalline cavities.2 Sometimes halophiles are also entrapped within salt inclusions.3,4 The quantity of fluid inclusion depends on the rate of crystal growth and chemically resembles the mother brine.2 Additionally, some chemical elements can replace sodium or chlorine in the NaCl crystalline network or be added as fine solid particles (inter- or intra-crystalline).2,5 The latter mostly originate from atmospheric deposition, brine particulate matter (mostly minerals from concurrent precipitation) and sediment substrates of the crystallization basins. In the past salt production was one of the main commercial activities in the Gulf of Trieste and Istria (northern Adriatic) but at the present time only the salinas at Secov-lje and Strunjan (Piran salinas) have been preserved. The Secovlje salina's history goes back to the 9th century6 but the earliest written sources regarding salt making are dated to the 13th century. In addition to the ancient procedure of salt-making the Secovlje salina, extending over 6.5 km2, also provides other aesthetic, cultural and natural values. Because of their exceptional landscape and ecological value, the Slovenian wetlands are also included on the Ramsar list. Today, the company Soline Pridelava soli, d.o.o. (Salt Production Co., Ltd)7 protects and preserves the natural and cultural heritage within Secovlje Salina Nature Park8 and produces and manufactures various salt products. There have been many studies of flora and fauna in the Secovlje salina and numerous publications are dedicated to its cultural tradition. However, there is a lack of investigation into the solid (sediment) and aqueous (brine) phases of salinas. The aim of this study was to investigate for the first time the detailed elemental and mineralogical composition of various salt samples from the Secovlje salina and to compare the results with those of commercially available unrefined salts with various geographical origins. 2. Materials and Methods 2. 1. Sampling Site The Secovlje salina (Figure 1) is located in the southern part of Piran Bay (northern Adriatic) on the estuary of the River Dragonja. The recent sediment of the salt pans (up to 90 m deep) is mostly composed of quartz, cal-cite and clay minerals such as illite, chlorite and kaolini-te.9 Adequate land and favourable climate conditions combine with high seasonal temperatures and winds for the solar evaporation of brine. The annual production of salt in the Secovlje salina varies from 200 to 4000 tons mainly depending on weather conditions that are important for evaporation (air temperature, wind frequency and intensity, and atmospheric humidity). Figure 1: Location of sampling site (Sečovlje salina) 2. 1. 1. Traditional Salt Production in the Se~ovlje Salina The basis for solar salt production is fractional salt crystallization leading to the recovery of NaCl through the natural evaporation and concentration of seawater in crystallization basins. The least soluble salt, calcium carbonate (CaCO3) precipitates first followed by gypsum (CaSO4 ■ 2H2O), halite (NaCl) and finally magnesium and potassium salts. The season for salt making usually begins in March with precipitation of NaCl in June/July/August. The salt making process includes the traditional manual technique that has remained virtually the same over time, that is, gathering salt from sea water by moving brine through a series of evaporation ponds until the salt is harvested in crystallization basins. Seawater (brine) salinities in the salt making system vary during the salt production season depending on weather patterns, water movements, operational demands and maintenance needs. The salinity of natural seawater within the intake canals usually equals about 36-38. Sea water is directed into a system of shallow ponds arranged in series. The first series represents the evaporation ponds: I followed by evaporation ponds II and III in successive order of evaporation. Each subsequent evaporation pond is more saline due to the specific operational system and to solar evaporation. Finally the brine is led into the crystallisation basins, covering about 6-7% of all basins, with the help of pumps. Salt precipitated on the crystallizer floor is raked with wooden scrapers into heaps or slopes with the natural inclination allowing surplus water to trickle away. Manually gathered dry salt is then transported in small wagons and stored in special depots. The crucial element in this mediaeval manner of salt-production is a microbial mat called "petola" i.e. a few millimeter thick surface layer9 covering the mud bottom of the crystallizing basins. In the saline ponds, these biomats (inorganic and organic fractions) have important roles: removing dissolved nutrients from the water, controlling water leakage and infiltration into the mud, immobilising large amounts of elements (also trace elements) and facilitating organic detritus decomposition.10,11 The petola is mostly composed of an inorganic fraction comprising carbonates, gypsum, quartz and clay minerals9,12 while organic matter represents a rather low share (organic carbon; 4.3-6.4 wt. %). Petola organic matter originates mainly from a microbial component dominated by cyanobacteria.9,13,14 During the wet season, organic decay processes and petola cementation lead to the very firm substrate needed for manual salt making.12 As mentioned above, the petola also prevents the brine and salt from mixing with the muddy floor resulting in the production of white and "natural" sea salt. Therefore special care is dedicated to the cultivation of this biological-chemical facet each year.14 In this traditional but strictly controlled method of salt production, the Piran salts (i.e. trademark name) are produced. In addition to the daily gathering of the salt on the petola, the artisan salt workers also collect Flower of salt. In a thin layer of the surface of the pans' salt basins the salt workers gently gather (by hand) the thin layer of salt crystallizing on the brine surface. The "hopper crystals" (upside down pyramidal structure in shape) of NaCl are typically (in addition to other components) present in that type of salt. Flower of salt is macroscopically characterized by small slightly pink crystals that could also sediment and contribute to salt gathered on the petola. These hopper crystals have fully developed edges and stairstep depressions on, or rather in, each crystal face. In rapidly crystallizing environments (salinas, evaporation lakes,...) the edges of the cubes simply grow faster than the faces, resulting in a series of depressed faces. Hoppering occurs when electrical attraction is higher along the edges of the crystal, causing faster growth at the edges than at the near face centres. This attraction draws the mineral molecules more strongly than the interior sections of the crystal, thus the edges develop more quickly.15 2. 2. Samples Characterization Salt samples from the crystallization ponds of the solar salt works of Sečovlje were randomly selected during the salt production seasons from 2004-2010. Two samples of different salt types (with trademark names Traditional salt and Piran salt), one sample of Flower of salt, one sample of natural bath salt and Piran Bay seawater in powder form were analyzed (indicated by a "PI" mark). Since we wanted to compare their quality with other natural salts, we also analyzed some commercially available unrefined salts with different geographical origins (Croatia, Austria, Italy, Portugal, India, and Pakistan) designated as Salt 1-Salt 6. All samples were stored in polythene bags and taken to the laboratory for further preparation and treatment. They were milled in an agate mortar to a particle size of less than 50 pm and then packed in clean, dry, stoppered glass containers and stored in a refrigerator. In order to define detailed mineralogical and elemental characteristics of different salt samples, X-ray Powder Diffraction (XRD) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) were employed. The mineral composition of the salt samples was determined by X-ray Powder Diffraction (XRD) using a Philips PW3710 X-ray diffractometer equipped with Cu Ka radiation and a secondary graphite monochromator. Data were collected at 40 kV and a current of 30 mA in a range from 2 to 70° 28/degree, with a speed of 3.0 2 8/min. The diffraction patterns were identified with the software X'Pert HighScore Plus with an installed PAN-ICSD database.16 In the case of the Pakistani salt the elemental analyses (FUS-MS, FUS-ICP, TD-ICP and INNA methods) were conducted by ACTLabs (Activation Laboratories Ltd., Ontario, Canada).17 The other salt sample results determined by the Aqua Regia Digestion Ultratrace ICP-MS method, were analysed for their detailed elemental composition in an accredited commercial Canadian laboratory (Acme Analytical Laboratories, Vancouver, B.C., Canada).18 For major elements, a 0.2 g sample was mixed with a mixture of lithium metaborate/lithium tetraborate and fused in a graphite crucible. Fused samples were diluted and analyzed by Perkin Elmer Sciex ELAN 6000/6100/9000 ICP/MS for the major oxides (SiO2, Al2O3, Fe2O3, MnO, MgO, CaO, Na2O, K2O, TiO2, P2O25) fo2r a3ll sa2mp3les and selected traces i.e. barium (Ba), beryllium (Be) and strontium (Sr) for the Pakistani salt sample (ACTLab FUS-ICP method). The molten mixture of fused samples were also poured into a 5% nitric acid solution, shaken for 30 minutes until dissolved then run for thorium (Th) and uranium (U) (including bismuth (Bi), gallium (Ga), germanium (Ge), hafnium (Hf), indium (In), molybdenum (Mo) and rubidium (Rb) for Pakistani salt) on a combination simultaneous/sequential Thermo Jarrell-Ash Enviro II ICP (ACTLab FUS-MS method). Samples for copper (Cu) and sulfur (S) detection, including silver (Ag), cadmium (Cd), nickel (Ni), lead (Pb) and zinc (Zn) for Pakistani salt, were digested with four acids and heated in several ramping and holding cycles to incipient dryness. At that point, samples were brought back into solution using aqua regia and analysed with Varian ICP (ACTLab TD-ICP method). For detection of cobalt (Co), chromium (Cr), mercury (Hg), selenium (Se) and gold (Au) in the Pakistani salt sample 1 g aliquot was encapsulated in a polyethylene vial and irradiated with flux wires and an internal standard at a thermal neutron flux. After seven days to allow Na-24 to decay the sample was counted on a high purity Ge detector (ACTLab INNA portion method). Trace elements (Ag, Ba, Be, Bi, Cd, Co, Cr, Ga, Ge, Hf, Hg, In, Mo, Ni, Pb, Rb, Se, Sr, Zn and Au) present in salt samples S-1, S-2, S-3, S-4, S-5 and Piran salts were detected after aqua regia digestion of equal parts concetra-ted HCl, HNO3 and DI H2O for one hour in a heating block of a hot water bath for low to ultra-low determination using inductively coupled plasma mass spectroscopy (AcmeLabs 1:1:1 Aqua Regia digestion Ultratrace ICP-MS analysis). Quality control and quality assurance (QCQA) of the salt sample analysis were assessed using the reference materials DS8 (AcmeLabs); NIST-694, DNC-1, NIST-1633b, W-2, SY-4, BIR-1A, GXR-1-4-6, SDC-1, JR-1 (ACTLab) and by the results of the duplicate measurements (see Table 1 and 2 for more details). In the case of high salt samples the important ICP-MS side product represent the ArCl+ (polyatomic interference) which has the same mass-to-charge ratio (m/z = 75) as arsenic (As). Therefore Flow Injection-Hydride Generation-Atomic Fluorescence Spectrometry (FI-HG-AFS) was used to determine arsenic concentrations in salt solutions.19 Prior to the arsenic analyses the salt samples (0.5 g) were dissolved in 5 ml of MilliQ water. 100 pl ali-quots were injected into a stream of mobile phase (15 mmol l-1 KH2PO4, pH 6.0) via Rheodyne injector and subjected to hydride generation in a PEEK cross. For hydride generation 2 mol l-1 HCl, 3.0 ml min-1 and 1.5% NaBH4 in 0.1% NaOH, 3 ml min-1 were added to convert non-volatile arsenic compounds into corresponding volatile hydrides, which were separated from liquid waste in an A-type gas-liquid separator (PS Analytical, UK), dried in a Per-ma-pure dryer under the a flow of nitrogen and detected using an Excalibur Atomic Fluorescence Spectrometer (PS Analytical, Kent, UK). Peak areas were compared to the peak area of As(V) standard (1-50 ng ml1, prepared from Merck Titrisol standard, 1.000 mg ml-1). Detection limits for arsenic were in the range of 0.5-0.8 ng ml-1 of injected solution (5-8 ng g-1 of salt). The same set-up as above, but with an additional UV-decomposition unit (FI-UV-HG-AFS), in which all potentially present arsenic compounds including organoarsenic compounds are decomposed with persulphate in alkaline conditions (3.0 K2S2O8 and 3.0% NaOH) to form As(V) was used to verify the results. Detection limits of this set-up were in the range of 2-3 ng ml-1 of injected solution (20-30 ng g-1 of salt) so that arsenic in most of the samples was at or below detection limit (data not given). 3. Results and Discussion The results of X-ray Powder Diffraction (XRD) of the studied samples are presented in Table 1. The mineral composition is characterised by high quantities of halite in Table 1: Major minerals found in salt samples Mineral Name Chemical Formulae Halite NaCl Gypsum CaSO4 • 2H2O Bischofite MgCl2 • 6H2O Langbeinite K2SO2 • 2MgSO4 Dolomite CaMg(CO3)2 Calcite CaCO3 Quartz SiO2 Sylvine KCl all investigated samples, followed by gypsum, bischofite, langbeinite and, in some samples, also by dolomite, calci-te, quartz and sylvine. The above mentioned results are also in accordance with mineralogical observations in different salts, shown by the CSIRO Minerals Report.20 Elemental analyses showed that six chemical elements sodium (Na), magnesium (Mg), calcium (Ca), potassium (K), sulfur (S), iron (Fe) together with chlorine (Cl) make up the majority of the investigated salt samples. Additionally, silicon (Si), aluminum (Al), phosphorus (P), manganese (Mn), titanum (Ti) contributed with minor concentrations in all salt samples (Table 2). Elemental analyses of selected samples showed similar concentrations in the case of Na, Fe, Al, Mn and Ti with greater differences observed for Mg, Ca, K, S, Al and P. The lowest content of Si was observed in Piran salts and the highest S concentration in the salt samples S-2 (Austria) and S-5 (India). Regarding the major elements in Piran salts the following sequence was observed: Na > Mg > Ca > S > Fe, K > P > Al > Mn > Ti (Traditional salt), Na > Mg > S > Ca > K > Fe > P > Al > Mn > Ti (Piran salt) and Na > Mg > S > K > Ca > P > Fe > Al > Mn > Ti (Flower of salt). Salt with the trademark names Traditional salt and Piran salt are both unrefined sea salt that is crystallized from brine, with an approximate density of 26 - 29 °Be and 28 - 31 °Be, respectively, and scraped by hand from the crystallization salt basins. Due to higher brine salinity, the Piran salt contains higher contents of magnesium components. Bitter salt (MgSO4 ■ 2 H2O) contributes to the slightly more bitter taste of Piran salt. On the other hand, the lowest Mg concentration was observed in Flower of salt. The data from regular quality analyses of salt (internal laboratory reports, Soline Pridelava soli, d.o.o. Company)21 are in accordance with our results. The main salts composition is presented in Table 3. Bromide concentrations were about 173-271 pg g-1 with iodine concentration lower than 0.5 pg g-1. Content of water in the salt samples estimated after the salt draining in storage was lower than 7% and the typical pH value of 20% salt solution was 8.44. 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Ci Ol y I/O £ Oi 7 ^U 60 o K o ID & S C o v T3 tJ "¡3 O ¡3 <> M O c^ c^ 0 C^ 0 C^ c^ 0 c^ C^ C^ vo 60 O CD C<0 CD CD CD CD CD CD CD CD CD CD CD iN CS <> iN IN IN CO CO IN 1—1 IN IN IN C^ C^ C^ C^ 0 c^ O O C^ C^ O >0 CD CD CD CD CD CD CD CD CD CD CD IN CS Oi PN vo 7 O IN 00 in D CD I/O c^ C^ C^ ,—1 0 C^ C^ c^ 0 c^ > D O CD CD CD CD CD CD CD CD CD CD CD CS O V V V V V S u S ü CS ta S > u Is § A T3 S - S Table 3: Major chemical composition of Piran salts (summarizing the results of internal laboratory reports of Soline Pridelava soli, d.o.o. Company)21 Average concentrations Content Cl Ca Mg SO4 K Unit cg g-1 cg g-1 cg g-1 cg g-1 cg g-1 Method ISO 2481:1973 ISO 2482:1973 ISO 2482:1973 ISO 2480:1972 ISO 9964:1993 PI - Piran salt 56.20 ± 1.50 0.21 ± 0.05 0.35 ± 0.09 1.07 ± 0.10 0.07 ± 0.00 PI -Traditional salt 56.08 ± 1.07 0.17 ± 0.05 0.28 ± 0.08 0.90 ± 0.21 0.07 ± 0.01 PI - Flower of salt 55.42 ± 1.05 0.06 ± 0.03 0.33 ± 0.05 0.68 ± 0.03 0.11 ± 0.03 While there is no international standard for unrefined sea salt, there is a Slovenian regulation for unrefined seawater (natural) salt (Rules on the quality of salt, OJ RS, No. 70/2003)23 that determines the quality of unrefined seawater (natural) salt. It must contain not less than 95% of pure NaCl on a dry matter basis, at least 0.1% Ca(II) and 0.2% Mg(II) and not more than 7% of water. The rest of the composition includes natural secondary products and natural contaminants. Amounts of minor elements detected in selected salt samples are presented in Table 4. Concentrations of Au, Be, Bi, Co, Cr, Ga, Ge, Hf, Hg, In, Mo, Ni, Sc, Se, Th and U in the Piran salts were consistently lower than 0.5 ^g g-1, while the average concentrations of Ag, Ba, Sr, Rb and Zn were higher than 0.5 ^g g-1. These values are in agreement with the results for commercially available unrefined salts. However, concentrations of trace elements in Pakistani salt were generally higher than the others (Table 4). Today, there is serious concern about toxic metals present in the environment and in food. As, Cd, Cu, Pb and Hg are the most important heavy metals which may cause different health problems after the consumption of contaminated foods.24-27 As, Cu and Pb are characterised as both vital and toxic for many biological systems and may enter food materials from soil through the mineralization of crops, food processing or environmental conta-mination.24-28 Children are particularly susceptible to Pb exposure due to high gastrointestinal uptake and the permeable blood-brain barrier.29,30 Cd is a very well-known and widespread environmental pollutant.24 In humans the biological half-life of cadmium is estimated to be from 10 to 30 years hence it accumulates in biological systems.31 Hg and most of its compounds are extremely toxic to humans and must be handled with special care.32 Although the adverse health effects of heavy metals have been known for a long time, exposure to heavy metals continues and in some countries is even increasing.27 Food is one of the major routes to widespread heavy metal contamination in the general population. Table salt is one of the most common food additives with a unique place in food consumption. Consequently, maximum limits for the presence of heavy metals in table salt have been established by the Codex of legislation (Codex standard for food grade salt).33 The Codex standard for food grade salt applies to salt used as an ingredient in food (for direct sale to the consumer and for food manufacturers) and to salt used as a carrier of food additives and/or nutrients. In this case the content of NaCl should comprise at least 97% (exclusive of additives). According to the Codex of legislation, the maximum tolerated amounts of heavy metals in salt are 0.5 |g g-1 for As, 0.5 |g g-1 for Cd, 2 |g g-1 for Cu, 0.1 |g g-1 for Hg and 2 |g g-1 for Pb. All salt samples are consistent (excluding the Hg and Pb data for the Pakistani salt) with recommended values. Regarding food-grade salts available in Slovenia, in addition to the National regulations (OJ RS, No. 70/2003; OJ RS, No. 101/2003),23 34 they also must comply with world regulations.32 Concentrations of As, Cd, Cu, Hg and Pb in Sečovlje natural salt samples correspond to the allowed maximum limits for the presence of toxic metals in salt. The amounts of heavy metals found in Sečovlje samples were: Cd (<0.01-0.02 |g g-1), Cu (<1-2 |g g-1), Hg (<0.005-0.007 |g g-1), Pb (<0.01-0.46 |g g-1), and As (0.012-0.026 |g g-1). Combining the data from both As measurements (FI- HG-AFS and FI-UV-HG-AFS) indicates that no considerable amounts of non-hydride forming arsenic compounds like, for example, arsenobetaine can be present in the Slovenian and in the other analysed samples. The average values of Au, Be, Bi, Co, Cr, Ga, Ge, Hf, Hg, In, Mo, Ni, Sc, Se, Th and U were lower than 0.5 |g g-1 in all investigated salt samples from Sečovlje (PI-samples). Average concentrations of Rb, Sr, Ba, and Zn, Ag, were: 0.1-1.9 |g g-1, 28.6-134.3 |g g-1, <0.5-1.7 |g g-1, <0.1-1.4 |g g-1 and <2 |g g-1, respectively. Soylak et al. (2008)35 analysed the trace metal content in 28 samples of refined and unrefined salt from Turkey, Egypt and Greece which showed the Cu, Ni, Co, Mn, Pb and Cd concentrations in the range of 0.17-0.47, 0.16-1.57, 0.22-0.48, 0.26-4.68, 0.50-1.64 and 0.140.30 |g g-1, respectively. The levels of the previously mentioned element (trace metals) concentrations in unrefined Turkish table salts (rock salt, salt from Salt Lake) were quite comparable to our results except for the Mn and Cu contents being higher in our case.35 The latter is much more similar to the Cu content (1.16-1.179 |g g-1) determined from the table salt samples from Nigde city (Turkey).36 Nickel concentrations in the selected natural salts were 0.2-0.9, in the Slovenian salts 0.1-0.4 |g g-1 and the nickel content of table salts from Kayseri-Tur- 7 (S s M ^ ö i U CD CD CD CD CD CD CD CD CD CD 0 60 o i 5 V V V V V V V V V V "T in M MO SC ^S AO ITj in in in in CO in in in o o o o o o o CD CD CD CD O CD CD CD CD CD CD CD CD CD CD V V V V V V V - 1 ^gö^ K ^o^ O IN IN IN IN IN CO IN IN IN IN IN C^ C^ O O O O O C^ C^ O CD CD CD CD CD CD CD CD CD CD V V V V V V V V V V (3 00 ^ £ « CD CD CD CD CD CD CD CD CD CD 60 CD i 5 u V V V V V V V V V V V CS in i/^ in i/^ i/^ Ja CD CD CD CD CD 60 CD i 5 u V V V V V 60 O =0 M o ^ O CS Ja CD CD u V V IN o C^ c^ c^ c^ o c^ o c^ CD CD CD CD CD CD CD CD CD V V V V V V V o V V « m 0 O M ^ 60 O C5 M in 93 6° o i ITj "T iN C3 ^ ^ 60 gl « Sg§ T3 O .a .¡a ccdc ti ¡DQ << in in in in in 0 0 0 0 0 tO VViNVVVVV ^ oooo O £3 IN IN IN IN IN IN IN IN IN IN C^ O O O C^ O O O C^ C^ S3 CD CD CD CD CD CD CD CD CD CD CD 00 CD V V V V V V V V V V V 11111* ^ OOOOOlOOOOO oo VVVVVVVVVVV ^ "ÎCOCO ^ in in i/^ CD CD CD V V V (N in o o IN IN IN * IN IN IN IN IN O O O O O O O O CD CD CD o in CD CD CD CD CD CD CD CD CD CD CD CD CD V V V V V V V V Hf^HN^HHHrjHN ooooooooooo i 00000000000 .¡3 "(S O -- _ S M , ^ ^ «OSes S œ « s » (S ° Si <8 0 Si - .2 V V V V V V V V V in in in in in in in in in in CD CD CD CD CD i—i CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD in V V V V V V V V V V j* 00 in £ << 5C 6JJ OlCu i ^u in 00 0^ in CO 0^ CO cK I/S CO CO IN CD 00 \D cK in IN o\ in IN O CO IN 00 60 O =0 ■C 00 ^ Ci 60 O i a egiJa « ^ 60 Ol C^ u M o 1 ^g T3 O .a .¡a ccdc ti in O .—1 iN o CO CO CO CO CO o O o o o O o o o o c^ O o o o o o c^ c^ c^ CD CD CD CD CD V CD o CD CD CD (N CO ^HCO 0000 v ^ ^ co co ^HOCD^H v vvv vvv - << in in in M ^^ Z iN c^ co o c^ c^ c^ c^ iN c^ 60 CD z o CD O o o CD CD CD O CD CD i V v v V V V V CO ^ ^H^O in 00000 O CO O^HOOO ž in co 00 in CD i T-H co C^ O Š O CD CD CD o in V O CD CD V CD CD O ^O OO (N ^ ^ ^ (N (N cicic^cjciv^cjc^c^cic^ v in 00 in ^ iN * co 00 CD CD CD O CD CD CD t-H CD CD CD CD O CD CD CD iN V O CD CD V O V O V Šs iN iN iN iN iN iN iN iN iN iN ES C^ O O O C^ O O O C^ C^ CD O O O O CD O O O O CD o CD S3 V V v v v V v v v v V s M , «.S3 s ¡.H e^i-še^ e- ^H rp TJ- up MS (¿(¿(¿(¿(¿(¿CM s « 5 » (S ° Si (S 0 Si 1 - .2