INFLUENCE OF AGRICULTURAL POLLUTION ON VERY SENSITIVE GROUNDWATER BODIES

INTRODUCTIONThe European Water Framework Directive 2000/60/EC (WFD) demandsthat EU member states establish a good chemical status of all ground- andsurface water bodies by 2015. A serious problem related to the possibilityof reducing chemical pollution arises in aquifers which are highlyvulnerable to pollution due to their specific hydrogeological and climaticproperties. In such aquifers, already a considerably small input ofpollutants causes a bad chemical status of ground- and surface waterbodies. Put into practice, this means that in order to attain a goodchemical status of water bodies, agricultural production would have to bepractically disabled, since it in most cases puts the most significantpollution load on groundwater.

Janko URBANC1 , Anja KOROŠA1, Tamara FERJAN STANIČ1, Dejan ŠRAM1, Jure KRIVIC1, Andrej JAMŠEK2, Sonja LOJEN3, Matjaž GLAVAN4, Marina PINTAR4

1Geological Survey of Slovenia, Department of Groundwater – Hydrogeology, Dimičeva ulica 14, 1000 Ljubljana, Slovenia; 2Institute of Agriculture and Forestry Maribor, Vinarska ulica 14, SI-2000 Maribor, Slovenia3Jožef Stefan Institute, Department of Environmental Sciences, Jamova cesta 29, 1000 Ljubljana, Slovenia4University of Ljubljana, Biotechnical faculty, Centre for Agrohydrology and Land Development, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia

Keywords: groundwater, Dravsko polje aquifer, groundwater contamination, groundwater protection area

DESCRIPTION OF WORKOur measurements showed that especially the southern part of the Dravsko poljegroundwater body is overloaded with nitrate. The large quantities of nitrogenwhich are produced here cannot be absorbed by the aquifer system without harm.The research shows that the biggest nitrogen pollution potential in the area is dueto cattle and the application of mineral fertilizers. Pig farms are a lesser source;even less nitrogen is produced by poultry, while the share of sheep and goats ispractically negligible. The potential of lowering nitrogen emissions from mineralfertilizers is expected to be significantly smaller.

STUDY AREADravsko polje aquifer is situated between cities Maribor (NW part) andPtuj (SE part). Aquifer represents a highly permeable (k=10-3 m/s)Qaternary aquifer with intergranular porosity. Main recharge sources areprecipitation (300 – 400 mm/year) and seepage from creeks fromPohorje in the western part of the area. General direction ofgroundwater flow is W – E, while locally deviations do occur. The aquiferis shallow and unconfined and as that, it is exposed to direct pollutionfrom the surface.

RESULTS AND DISCUSSIONHydrochemical balance show that nitrogen input should be lowered approximately by 1/3 in order to establish a good chemical status of groundwater body.This is a very high degree of reduction, meaning that radical changes in the way of farming in this area would be necessary. Therefore we see a great need forthe introduction of animal manure processing technologies in this area, which would enable the reduction of nitrogen leaching into groundwater and intodrinking water resources.

REFERENCESPrestor, J., Janža, M. 2006. Ocena višine infiltracije (po metodi Kennessy) in ranljivosti podzemnevode na območju Slovenije. Archive of Geological Survey of Slovenia, Ljubljana.Urbanc, J., et al., 2013: Možnosti kmetovanja na vodovarstvenih območjih (Possibilities ofagricultural activities in the groundwater protection areas). Archive of Geological Survey ofSlovenia, arch. No. K-II-30d/c-1/785 Ljubljana.Žlebnik, L. 1982. Hidrogeološke razmere na Dravskem polju. Geologija, 25, p. 151- 164

ACKNOWLEDGMENTPresented research is a part of the project „Možnostikmetovanja na vodovarstvenih območjih/Possibilities ofagricultural activities in the groundwater protection areas“carried out in the scope of Target Research Programme„Competitiveness of Slovenia 2006 – 2013“, financed by theMinistry of Agriculture, Forestry and Food, and SlovenianResearch Agency.

Mean concentration of nitrate in the groundwater of Dravsko polje aquifer

0 200 400 600 800 1000 1200 1400 1600 1800

Nitrogen (t/year)

Dravsko polje - southern part

FARMING N

POPU

LATION

PRECIPITATIONCATTLE PIGS

LOSSES41 %

MINERALFERTILIZERS

PO

HO

RJE

OTHER SOURCES

TOTAL GROUNDWATER NITROGEN5212 t

MAX. 663 t/year

NITROGENPOTENTIAL1420 t/yearPO

ULT

RY

Illegal livestock mud deposition