Posters Session I
M. S. HAMZA
IAEA-CN-104/P-60 STUDY OF THE POLLUTION IMPACT FROM THE USAGE OF SEWAGE AND DRAINAGE WATERS ON THE GROUNDWATER OF THE QUATERNARY AQUIFER, WEST CAIRO, EGYPT
The intensive use of fertilizers and wastewater in agricultural practices in the studied area led to increase in nitrate, phosphate, trace elements and high quantities of microbial organisms in some surface and groundwater samples. High concentration of NO-3 than the maximum recommended limit for drinking water (> 45 mgl-1NO-3, WHO, 1993)[2] was found in groundwater samples north of Abu- Rawash. The concentration of trace elements (Mn, Fe, Zn, B, Cd, Cu, Ni and Pb) in surface water samples are higher than that present in groundwater whereas most metal shave fairly limited mobility in soil and groundwater due to cation exchange or sorption of these elements on clay surface. High concentrations were detected more than the maximum recommended limit for drinking water in Mn, Fe, Cd, Ni and Pb of some surface and groundwater especially in east and middle parts of the studied area are attributed to the presence of sewage effluent in the surface channels. From the microbiological analyses, all sites of surface water and some groundwater especially shallow wells near by the sewerage stations are contaminated with all microbial indicators. So the use of effluent, drainage water and sludge in agricultural practices for long run will threat the surface water bodies and it’s under laying aquifer as well as the human health.
REFERENCES:
[1] CLARK, F.W., 1997: Environmental isotopes in hydrology, Lewis Publishers, Bacaraton, 328 p.
[2] World Health Organization (WHO), 1993: Guideline for drinking water quality, Volume 1.Second edition, Geneva, 188 p.
IAEA-CN-104/P-62 HYDROCHEMISTRY AND ISOTOPE GEOCHEMISTRY AS MANAGEMENT TOOLS FOR GROUNDWATER RESOURCES IN MULTILAYER AQUIFERS: A STUDY CASE FROM THE PO PLAIN (LOMELLINA, SOUTH-WESTERN LOMBARDY, ITALY)
G. PILLAa, E. SACCHIa, G.M. ZUPPIb, G. CIANCETTIa, G. BRAGAa
aDipartimento di Scienze della Terra, Università di Pavia, Via Ferrata 1, 27100 Pavia, Italy
bDipartimento di Scienze Ambientali, Università Ca' Foscari di Venezia, Calle Larga S.
Marta, Dorsoduro 2137, 30123 Venezia, Italy
The Po plain, located in Northern Italy, hosts a multi-layer alluvial aquifer of Quaternary age constituted by sands interbedded with clays. The plain supports most of the agricultural and industrial activities of Northern Italy, which are associated with groundwater pollution in the shallower portions of the aquifer. The increasing demand of water for industrial and domestic use has led to the exploitation of deeper layers of the aquifer, without a rational management of the resource. Only in the last decade, the government agencies have started a global evaluation of the quality standards of pumped groundwater, urged by the increasing need for clean water for domestic use. The task is particularly difficult because of missing or approximate well logs and the presence of multi-filter wells tapping in different aquifers. In this case the chemical and isotopic characterisation of groundwaters is the only reliable tool to reconstruct the geometry, the interconnections and the characteristics of the aquifers.
This study, promoted by the local agency for groundwater management and protection (Amministrazione Provinciale di Pavia, settore tutela e valorizzazione ambientale - U.O.C.
Acqua) focused on a limited portion of the Po plain, the Lomellina region, of approximately 900 km2. The region is bound to the South by the Po river, to the East and West by the Sesia and the Ticino rivers respectively, and to the North by the administrative boundary. The study aimed at the hydrogeological, hydrochemical and isotopic characterisation of the aquifers, allowing to serve as basis for the correct management of the groundwater resource.
A preliminary reconstruction of the hydrogeological asset of the Lomellina plain was performed through the analysis of the stratigraphic data from 102 municipal wells. On this basis, a shallow phreatic aquifer, reaching depths of about 50-60 m from the surface, and two groups of aquifers containing confined groundwater, were distinguished. All data were georeferenced and integrated in a GIS database. Subsequently, 40 wells and natural outflows were selected for the hydrochemical and isotopic characterisation. The selection was performed in order to cover homogeneously the studied region both in terms of extension and depth. Analyses included major ions, trace elements, pesticides, stable isotopes of the water molecule, 13C and 14C of dissolved inorganic carbon. Shallow waters containing high levels of nitrates were considered for the isotopic analysis of 15N and 18O of NO3-.
Hydrochemical analyses defined the hydochemical facies as calcium-bicarbonate.
Groundwaters generally show a decreasing conductivity and mineralisation with depth. The phreatic aquifer displays evidence for groundwater pollution from agricultural activities,
Activity diagrams clearly allow the distinction between the phreatic aquifer and the confined aquifers, which display a higher degree of interaction with the aquifer matrix.
Stable isotopes of the water molecule are in agreement with the results form adjacent sectors of the Po plain (Pilla, 1998), evidencing the lateral continuity of the aquifers. The phreatic aquifer and the different confined aquifers may be distinguished on the basis of their isotopic composition, which also allowed to verify their hydraulic confinement of deeper aquifers.
Intermediate aquifers are in part recharged by the shallow phreatic aquifer, which in turn is fed by local infiltration and by streams and irrigation channels.
The isotopic analysis of nitrates of 10 waters samples from outflows and shallow wells confirms the agricultural origin of contaminants in the phreatic aquifer. The isotopic signature is typical for the nitrification of synthetic fertilisers (Clark and Fritz, 1997). A correlation of the isotopic composition with nitrate concentrations (and consequently with depth) is also observed.
Carbon-14 activities and 13C data for DIC indicate a possible input of dead CO2 coming from the decomposition of the organic matter at depth, affecting the age corrections and precluding a precise dating. This is particularly observed for deep aquifers and is in agreement with what evidenced in similar hydrogeological situations in the Po plain (Zuppi and Sacchi, 2002).
Nevertheless, 14C indicates long residence times for deep waters, in the order of thousands of years. This information, coupled with the high quality standards of groundwater raises some concern about their exploitation for use other than domestic.
All hydrochemical and isotopic data, included in a georeferenced GIS database, provide the local administration with a powerful management tool for monitoring groundwater quality, enforce better agricultural practices, implement remedial actions for local pollution problems and plan a rational development of the groundwater exploitation.
REFERENCES:
[1] CLARK and FRITZ (1997) - Environmental isotopes in hydrogeology. CRC Press, Boca Raton
[2] PILLA, G. (1998) - Caratterizzazione idrochimica e geochimica isotopica delle falde nel sottosuolo della città di Pavia. Atti Tic. Sc. Terra 40, 185-201
[3] ZUPPI, G.M. and SACCHI, E. (2002) - Hydrogeology as a climate recorder: Sahara (North Africa) and the Po Plain (Northern Italy). Global and Planet. Change, in press
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