Posters Session I
R. GONFIANTINI
IAEA-CN-104/P-63 LANDFILL POLLUTION CONTROL WITH ISOTOPE TECHNIQUES
A. TAZIOLI, G.S. TAZIOLI
Department of Physics, Materials and Environmental Engineering, University of Ancona, Italy
will be performed on leachate in order to establish their isotopic ranges, and in groundwater in order to assess if these compounds derive from the landfill.
Table 1. Values of tritium activity, δ18O and δ2H content in landfill areas.
LANDFILL Sample location δ18O ‰ SMOW δ2H ‰ SMOW 3H (TU ± 1) Colle Leva Leachate -5.57 -34.58 13.2
Well 1 -6.47 -41.10 8.2
Well 4 -8.42 -54.24 8.9
Senigallia Leachate - - 249.3
Well 5 - - 7.7
Well 8 - - 4.5
Filottrano Leachate -5.36 -33.06 53.0
River 1 -6.89 -43.15 4.6
River 2 -9.64 -63.99 4.8
FIG. 1. Rainwater tritium content trend FIG. 2. Relationship between δ18O ‰ and during water year, in rainfall on the altitude of springs, in the Apennines in Apennines in proximity of Ancona. proximity of Ancona.
0 2 4 6 8 10 12 14 16
Jan Feb Mar Apr May Jun Jul Aug Sept-0ct Dec
TU
REFERENCES:
[1] PELLEGRINI, M., TAZIOLI, G.S., MUSSI, M., CALESTANI, G., MASSERANO, M., VANNUCCHI, M., Chemical and isotope methods for the identification of unmonitored old landfills polluting the underground environment, IAEA-SM-361/63P (1999).
[2] FRÖHLICH, K., Isotope techniques in groundwater pollution studies, Consultants Meeting, Vienna, 6-9 Dec. 1993, IAEA 1-12 (1994).
[3] TAZIOLI, G.S., Isotope and tracer techniques applied to studies of sanitary landfills and to an industry for galvanic treatment, Consultants Meeting on Isotope Techniques in groundwater pollution studies. Vienna 6-9 Dec. 1993, IAEA 36-48 (1994).
IAEA-CN-104/P-65 ISOTOPES HYDROLOGY OF SIMBRUINI MOUNTAINS (CENTRAL APENNINES, ITALY)
P. BONO1, A. RAPONI 1-2, B. TURI 1,G. M. ZUPPI3
1Dipartimento di Scienze della Terra, Università di Roma “La Sapienza”- IGAG –CNR, Italy
2Geokarst, Area di Ricerca, Trieste, Italy
3Università Ca’ Foscari di Venezia, Italy
The combined study of oxygen and hydrogen isotopes in karst groundwater is an excellent tool for exploring hydrological fluxes and meteorological variabilities at a regional scale. The interest for the hydrological and isotopic studies in the carbonatic Apennines (Central Italy) is explained by the large exploitation of the aquifers for several different purposes (civil, agricultural and industrial).
Limestones and dolostones of Mesozoic age form the axis of the peninsula in Central Italy.
The carbonates are and fractured and karstified and provide good conditions for infiltration. It has been shown (Boni and Bono, 1982; Boni et al., 1986) that the structural geology of the area is complex and that discontinuities at regional scale are abundant. Preferential deep circulations are linked to those structural systems. Because of the tectonic features one can assume that water circulation in depth is rather slow, and the signals of natural tracer are smoothed.
The objectives of the study are: (1) to identify recharge zones and flow patterns, calculate recharge rates or mixing ratios, and to discern hydraulic connections between aquifers; (2) to characterize the hydrogeochemical features of the karst groundwater system as a typical case in central Italy; and (3) to show the effectiveness of geochemical analysis techniques to extract hydrological information from hydrogeochemical data. As a major diagnostic tool in groundwater hydrology, hydrogeochemical data have been used to identify recharge zones and flow patterns, calculate recharge rates or mixing ratios, and to discern hydraulic connections between aquifers.
Water chemistry and isotopes in springs have been used extensively to study aquifers, based on samples and data collected from 10 rain gauges on a transect West – East from the Tyrrhenian Sea and 10 springs. Typically, studies have focused on either: long-term rainfall data collected at biweekly or monthly intervals or higher resolution analysis of single storm events. Analysis of δ18O in spring waters has yielded, indirectly, information about groundwater residence times.
In the Italian peninsula, rainfall and groundwater samples show differences in their isotopic composition. These differences are related to the contrast existing between water vapour of Atlantic origin and water vapour of south-western Mediterranean origin and indicate a strong correlation between isotope contents and altitude. However, the complexity of the hydrologic situation cannot be appraised by the study of single event, since the isotopic records from the
continuous change of the influence of the Mediterranean and Atlantic Ocean on isotopic composition of the rainfall.
The determination of recharge altitudes can be estimated both through the use of the isotopic content of infiltrated water, and the isotope composition of shallow groundwater. In fact, the latter must be representative of the mean local composition of the present-day precipitation.
The data from the Simbruini Mountains and those of the local GNIP stations give a 18O- altitude gradient close to – 0.0020.The good correlation of 18O with altitude (r2 = 0.98) shows that an orographic effect is present whatever is the origin of air masses.
As previously mentioned, the groundwater isotopic composition indicates that precipitation reflects the origin of air masses participating to the aquifer recharges on the Apennines and the mean elevation of infiltration areas. This can be questioned, since only a single rain event is used to characterise the isotopic signature of the precipitation in an area, which is known for the occurrence of precipitation of both Mediterranean and Atlantic influences. Isotopic studies on rainfall in the central and western Mediterranean basin, and the relative proportion of south-west and north-west precipitation has been determined in several stations and state that precipitation are typically aligned in a 2H–18O diagram on a local meteoric water line with a deuterium excess varying between +12 and + 14.5 (Chery, 1988; Panichi et al., 1992; Celle et al., 2000). The distinct isotopic signature of precipitation with a Mediterranean origin has been used, already, in hydrological studies in the Central Apennines (Zuppi and Bortolami, 1982; Governa et al.,1989). However, these studies do not address the spatial variation in isotopic signature inside a large aquifer system, for which source and age interpretations are known to be difficult.
The differences related to the contrast existing between water vapour origins are reflected in shallow groundwater characterised by a fast circulation. On the contrary the signal homogenisation is dominant in deep groundwater. Firm conclusions on the causes of this pattern are drawn at this stage, because the isotopic signatures of rainfall events are extreme and in agreement with the air masses movement above Mediterranean regions. The fact that groundwater has very different oxygen-18 values means that circulations are short and fast and seasonal signals could be maintained. In such a case, the isotopic content can provide also a useful tool for analysing in detail the characteristics of the recharge.
Accurate dating of deep groundwater is not possible due to the lack of a long-term record of the tritium transient in this area, as well as the slow change in tritium concentrations over the precipitations in the past years. Moreover the measured tritium concentrations in groundwater are affected by hydrodynamic dispersion and mixing of different age waters over the length of the screened sampling interval. However, the tritium concentrations appear to be compatible with the estimates of high recharge rates and high transmissivity of the Mesozoic aquifer in the study area.
REFERENCES:
[1] BONI, C.F.; BONO P. (1982). Lineamenti geologici e idrogeologici dell’Appennino Umbro-Marchigiano e Laziale-Abruzzese. PFE, RF15, PEG (Milano), 86-98
[2] BONI, C.; BONO, P., CAPELLI G. (1986). Schema idrogeologico dell’Italia Centrale.
Mem. Soc. Geol. It., 35 : 991 – 1012, 2 tavv.
[3] BONO, P; PERCOPO, C. (1996) Flow dynamics and erosion rate of a representative karst basin (Upper Aniene River, Central Italy). Environmental Geology 27 : 210 – 218
[4] CELLE, H.; DANIEL, M.; MUDRY, J., Blavoux B.(2000). Signal pluie et traçage par les isotopes stables en Méditerranée occidentale. Exemple de la région avignonnaise (Sud-Est de la France). C. R. Acad. Sci.Paris, Sciences de la Terre et des Planètes, 331 (série II), 647-650.
[5] CHERY, L. (1988). Essai de caracterisation géochimique et isotopique d’emergences de circulations profondes dans deux types de massifis granitiques: Auriat (Creuse) et La Sposata (Corse). Thèse Docteur en Sciences, n° 628, Université de Paris- Sud, Orsay, 224 pp.
[6] GOVERNA, M.E.; LOMABARDI, S.; MA SCIOCCO, L.; RIBA, M.; ZUPPI, G.M.
(1989).Karst and geothermal water circulation in the Central Appennines (Italy). In Isotope Techniques in the Study of the hydrology of Fractured and Fissured Rocks - IAEA, Vienna, 173-202.
[7] PANICHI, C.; BOLOGNESI, L.; GHIARA, M.R.; NOTO, P. and STANZIONE, D. (1992). Geothermal assessment of the island of Ischia (southern Italy) from isotopic and chemical composition of the delivered fluids. J. Volcanol. Geotherm.
Res. 49, pp. 329–348
[8] ZUPPI, G.M. and BORTOLAMI, G. (1982). Hydrogeology: a privileged field for environmental stable isotopes applications. Some Italian examples. Rend. Soc. It.
Petrol. Mineral. 38 3, pp. 1197–1212.
FIG. 1 – Mounts Simbruini karstic range: Schematic geological and hydrological setting.
1, Undifferentiated dolomitic complex (Upper Triassic; Lower Cretaceous); 2, Undifferentiated limestone complex (Jurassic; Upper Cretaceous; Lower Miocene); 3, Fault; 4, Overthrust; 5, Watershed area; 6, Major permanent karst springs (1:. Inferniglio, 2: La Foce, 3: Pertuso); 7, Flow gauging station and monitoring reference point of chemico-physical parameters. (From Bono P. and Percopo C., 1996)
IAEA-CN-104/P-67 DEUTERIUM AS REFERENCE IN A MULTITRACING EXPERIMENT IN A KARST SYSTEM – A COMPARATIVE STUDY
R. BENISCHKE, A. LEIS & H. STADLER
Institute of Hydrogeology and Geothermics, Joanneum Research, Graz, Austria
Deuterium was used as a reference tracer for a multitracer experiment in a karst cave system in the Central Styrian Karst, Austria. As tracers two fluorescent dyes (Na-Fluorescein and Sulphorhodamine G), one inorganic salt tracer (Sodium Bromide) and one isotopic tracer (Deuterium) were used in a comparative study.
The karst cave system which is situated in paleozoic limestone allows access to open underground galleries with active channel flow, and therefore offers a good opportunity to control the boundary conditions during injection, such as the flow conditions during the experiment and the specific details of channel topology.
The objective was to compare different types of tracers, their behaviour during transport and the degree to be classified as conservative or non-conservative. The tracer transport in the underground channel was monitored with different systems, but also water samples were collected by automatic samplers for later laboratory analysis. Fluorescent dye tracers were measured online with a 2-channel fiber optic fluorometer with built-in data-logger and the sodium bromide tracer was measured for Bromide with a Br-selective electrode. To have parallel sample records the collected water samples were analyzed quantitatively with a laboratory scanning-fluorometer for the dye tracers, separately for Sodium and Bromide by ion-chromatography and for Deuterium by mass spectrometry.
In addition to the tracers of interest flow conditions (water level with a pressure probe) and physical parameters (electrical conductivity and water temperature) were monitored. The latter as well as the Bromide data were recorded with data-loggers.
The achieved breakthrough-curves of individual tracers were compared to each other and analyzed for shape and characteristic time-marks (e.g. first appearance, peak and center-of- gravity), for retardation and mutual cross-over effects.
The result was, that Deuterium and Bromide showed the highest degree of conservativeness.
Na-Fluorescein and moreover Sulphorhodamine G showed retardation compared with Deuterium and Bromide. A direct comparison was difficult due to the different sensitivity of the analytical procedures, because sensitivity of dye tracer analytics as well as Bromide and Deuterium analytics differ from each other over several order of magnitudes.
IAEA-CN-104/P-70 ISOTOPE HYDROLOGY OF THE MULTI LAYER AQUIFER IN N.E. BUENOS AIRES PROVINCE. ARGENTINA
S. PERA IBARGURENa, H. PANARELLOb, J. AINCHILc, G.M. ZUPPIa
aUniversità Ca' Foscari, Dipartimento di Scienze Ambientali
bInstituto de Geologia y Geocronologia Isotopica
cUniversidad Nacional de La Plata
The study area is located in populated areas of the coastal plain of the Rio de la Plata between Buenos Aires and La Plata (figure 1). Water supply of the region is done both by groundwater and by Rio de la Plata treated water. Suburban areas are mainly served by groundwater pumped from the Puelche, regional semi-confined aquifer, although domestic wells exploit the Pampeano free aquifer, containing the phreatic layer. On the contrary Buenos Aires metropolitan area is served by river water.
The coastal plain is characterized by elevations ranging from 0 to 5 metres above sea level and by a width of 1.5 to 7 km. This is an area where small differences in elevation (0.15 – 0.30 m) lead to the development of marshes that catch the rain and runoff from the high areas.
Moreover, under certain metheorological conditionss (atlantic storm “Sudestada”), with strong wind blowing form SE, generally accompanied by heavy rains, the plain is partially flooded by the Rio de la Plata.
In the coastal plain, groundwater from the phreatic and Puelche aquifers is brackish due to a marine transgression occurred at ca. 9000 years BP. 2H and 18O contents of surface water and from both aquifers present distinctive characteristics. River water is isotopically enriched with respect to ground water (although seasonal variations does exist, Panarello and Dapeña, 2001), whereas tritium contents in the river water are significantly high because of the upstream existence of a nuclear power station.
The saline / fresh water interface is well known and described for the inland environment by several authors (Hernandez, 1978, EASNE, 1972, Panarello et. al 1994 ). The aim of this work is to investigate the (brackish) groundwater / (fresh) river water interface in the coastal zone, in the Puelche and Post Pampeano/Pampeano hydrogeological units by using environmental isotopes, geochemical analysis and geophysical techniques.
Results
Geophysical survey VES-1, and VES-2 show an increase of resistivity corresponding to the Puelche aquifer. The first profile, performed on the sand bar, shows high values in the upper part of the curve (Post-Pampeano unit), whereas the second profile suggests a lateral migration (landward) of the interface. 1-D interpretation model suggest a four layer arrangement
Tritium concentrations indicate that the Puelche aquifer is partially recharged from the Rio de la Plata. In fact, tritium content of qpc-3 well is 14.3 TU, and at the same time Cl- concentration is very low.
Within the Post-Pampeano aquifer, groundwater stratification exists. Water from qpc-2 and hpc-3 wells and water pumped in the upper levels of the aquifer show higher tritium contents than water from hpc-2 and qpc-5 and that collected at the deepest levels. In other words, the Post-Pampeano aquifer receives an active recharge, at least, in the upper part.
The geochemistry confirms the stratification within the Post-Pampeano unit (table 1).
Conclusions:
In the sand bar level, the hydraulic conductivity is higher than in other zones of the coastal plain, as result of its sedimentological characteristics.
Surface water level increase due to tide and metheorological events, favours an active recharge of the phreatic aquifer from the river (bank storage phenomena), as indicated by changes in hydraulic head and, sometimes, temporary inversion of the hydraulic gradients.
The result is a dynamic stratification of groundwater with an upper zone of the aquifer containing less mineralized young groundwater grading to brackish old water from the marine transgression, through a thick interface where diffusion and hydrodynamic dispersion occurs.
In the Puelche aquifer the influences of tidal movements should be presents; but they are negligible considering the groundwater exploitation occuring in land. Permanent inversion of the landward hydraulic gradients (originally coastward) generates recharge from the river that acts as a “positive” barrier, and a lateral migration of the interface.
Besides, the Puelche aquifer receives active recharge from the river, with water circulating within sediments containing levels of organic matter that turns redox potential to negative values.
well name hpc-2 hpc-3 qpc-2 qpc-3 qpc-5 rq-1 rh-1
well depth (m) 10 2.9 8 25 15 river river
Aquifer Phreatic Phreatic Phreatic Puelche Phreatic
λ(µS/cm) 4100 141 1850 1400 10300 290 500
Cl (ppm) 974.26 5.1 124.84 83.4 4276.4 59 38
Tritium (TU*) 4.2 9.3 7.4 14.3 0.0 25.9 38.0
* Table 1
Fig.1
REFERENCES:
[1] EASNE, Estudio de las aguas subterraneas del NE de la Provincia de Buenos Aires.
Min. Obr. Y Serv. Publ. Provincia de Buenos Aires.
[2] HERNANDEZ, M.A. Reconocimiento hidrodinamico e hidroquimico de a interface agua dulce agua salada en las agues subterraneas del estuario del plata. Partidos de Quilmes y Berazategui. Proc XII Cong. Geol. Arg. Vol. 2. AGA, Buenos Aires pp 273- 285
[3] PANARELLO, H.O. and DAPEÑA, C., 2001. Stable isotope composition of the Rio de la Plata estuary: an attempt to relate to meteorological variables. III South American Sympusium on Isotope Geologýa. Pucón, Chile. Actas CD. ROM.
[4] PANARELLO, H.O.; DAPEÑA, C.; AUGE, M. Estudio isotopico de la salinizaciòn del agua subterranea en la ciudad de La Plata y sus zonas vecinas, Buenos Aires Argentina.
Proc XII Cong. Geol. Arg. Vol. 6. AGA, Buenos Aires pp 146-152.
IAEA-CN-104/P-71 ORIGIN AND EVOLUTION OF HIGH PH MINERAL WATERS TRACED BY ISOTOPE GEOCHEMISTRY (S-PORTUGAL)
J. M. MARQUESa, M. ANDRADEb , F. GOFFc , M. J. BASTOa, M. J. MATIASa, R. C.
GRAÇAa, P. M. CARREIRAb, L. AIRES-BARROSa, L. ROCHAd
aInstituto Superior Técnico, Lisboa, Portugal
bInstituto Tecnológico e Nuclear, Portugal
cLos Alamos National Laboratory, Los Alamos, New Mexico, USA
dJunta de Freguesia de Cabeço de Vide, Portugal
Cabeço de Vide mineral waters are considered an important natural resource of the region.
Isotope geochemistry has greatly contributed to the elaboration of a conceptual hydrogeological model associated with these mineral waters. This conceptual model has been adopted by the local authorities for the re-definition of well-head and aquifer protection areas.
In the study area, the topography rises gradually from Cabeço de Vide Spas (≈ 250 m a.s.l.) to Portalegre city (≈ 620 m a.s.l.), after which the gradient becomes steeper, with a maximum elevation at the crest of the S. Mamede Mountain (1027 m a.s.l.) about 25 km NE Cabeço de Vide Spas. The geology of the region is dominated by the Lower Cambrian carbonate sequence that was intruded and metamorphosed by a heterogeneous suite of mafic (gabbros) and ultramafic (dunites) rocks forming an NW-SE cumulate-type structure of Ordovician age.
The ultramafic rocks are highly serpentinized.
Groundwater samples for chemical and isotope analysis were collected from springs, dug and drilled wells located either in the surroundings of Cabeço de Vide Spas or along the main NNE-SSW trending fault, towards Portalegre city. Cabeço de Vide mineral waters belong to the Na-Cl/Ca-OH-type (pH ≈ 11.5) and issue from the intrusive contact between the mafic/ultramafic rocks and the carbonate sequence. The local Mg-HCO3-type waters, typical of waters issuing from serpentinites [1], constitute most of the shallow groundwaters discharging from ultramafic rocks. In fact, the Mg-HCO3 waters of Cabeço de Vide area are undersaturated with respect to chrysotile, corroborating the idea that water chemistry is strongly dependent of serpentine dissolution. On the other hand, the Cabeço de Vide mineral waters are undersaturated with respect to forsterite but supersaturated with respect to chrysotile, indicating that they could be responsible for the serpentinization process of the ultramafic rocks. The 2H and 18O results were used to estimate the relative importance of recharge by local precipitation vs groundwater infiltrated at higher slopes. The long-term mean of 18O and 2H values of precipitation collected in Portalegre meteorological station (597 m a.s.l. / approximately 15 km NE of Cabeço de Vide) was used in our interpretations [2]. Similar isotopic (2H and 18O) signatures were observed in both mineral and local Mg- HCO3 water samples (Fig. 1). Considering the isotopic composition of precipitation at Portalegre meteorological station ( 2H = -32.2 o/oo; 18O = -5.44 o/oo) we can admit that the Cabeço de Vide mineral waters are apparently recharged at low elevation sites where ultramafic rocks occur. Also, this pattern indicates that the contribution of recharge from
suggest that groundwater recharge corresponds to an age older than 50 years. On the contrary, the 3H concentrations in most surface and shallow groundwater samples were up to 7 TU.
-35 -33 -31 -29 -27 -25 -23 -21 -19 -17 -15
-5.5 -5.3 -5.1 -4.9 -4.7 -4.5 -4.3 -4.1 δ18O (o/oo vs V-SMOW)
2 H (o /oovs V-SMOW) schists
granites gabbros serpentinites CV Spas limestones stream
rain (Portalegre) δ 2H = 8 δ18O + 10
Fig. 1 - δ2H vs δ18O relationship in water samples from Cabeço de Vide area. (ν) Cabeço de Vide mineral waters; (λ) stream waters; waters from: (x) granites, (∆) gabbros, (σ) serpentinites, ( ) limestones and () schists. (Θ) Portalegre precipitation.
The δ13C values of -22.9 o/oo and -18 o/oo vs PDB (waters from drilled wells AC3 and AC5, respectively) points out for: i) an organic origin for the carbon in the Cabeço de Vide mineral waters, and ii) a negligible contribution of carbon from the Lower Cambrian carbonate rocks (presenting δ13C values around +1.48 º/oo vs PDB) to the isotopic signatures of Cabeço de Vide mineral waters. Two samples for 14C content determinations of Cabeço de Vide mineral waters were collected (AMS determinations - Geochron Laboratories / USA). The values obtained range between 69.12 ± 0.28 and 65.24 ± 0.35 pmc, indicating an apparent groundwater age between 2970 ± 40 and 3430 ± 50 years BP, respectively. Recent research on the progressive evolution from rainwater to neutral Mg-HCO3 waters and to mature, high- pH, Ca-OH waters indicate that Mg-HCO3 waters could be generated in the first step, under open CO2 conditions, whereas Ca-OH waters are produced in the second step, under closed- system conditions [3]. Since, in our case, both Mg-HCO3 and Cabeço de Vide mineral waters (Na-Cl/Ca-OH type waters) have similar isotopic (2Hand 18O) signatures, we can formulate the hypothesis of an evolution from the local Mg-HCO3 waters towards the mineral waters.
REFERENCES:
[1] BARNES, I., LAMARCHE, V. C. Jr. and Himmelberg, G. R. (1967) Geochemical evidence of present-day serpentinization. Science, 56, 830 - 832.
[2] Instituto Tecnológico e Nuclear (2002) Precipitation data base. Portalegre meteorological station (1988 – 2002).
[3] BRUNI, J., CANEPA, M., CIPOLLI, F., MARINI, L., OTTONELLO, G., VETUSCHI ZUCCOLINI, M., CHIODINI, G., CIONI, R. and LONGINELLI (2001) Reactions governing the chemistry of waters interacting with serpentinites. Water-Rock Interaction 2001, Cidu (ed.), 145 – 148.