Geochemical and geophysical data were collected across Northern Ireland (14,000km2) as part of the Tellus project between 2004-07. The project was managed by the Geological Survey of Northern Ireland with logistical input from the British and Finnish Geological Surveys.
Magnetic, electromagnetic and radiometric data were collected at an elevation of 56m along flight lines spaced 200m apart. Multi-element geochemical data were obtained from stream water, sediment and soils (20cm and 50cm depth; 1 sample per 2km2). Soils, collected throughout the two largest cities were analysed for organic and inorganic compounds. In conjunction with existing digital data, Northern Ireland is probably the most rigorously geoenvironmentally surveyed part of the Earth.
The geology of Northern Ireland can be described in quadrants. The NE comprises Palaeogene basalts, the SE Lower Palaeozoic sediments with granites, the SW Carboniferous limestones and shales and the NW Dalradian schists.
Soil samples from the Palaeogene basalts are highly anomalous in Ni and associated elements, with the majority exceeding the UK Soil Guideline Value for Ni of 50ppm (maximum 333ppm). This has resulted in re-examination of policy to take natural elemental levels into consideration. Soils also represent a significant store of carbon. Initial studies indicate the integration of radiometric survey data represents a useful secondary data source to improve estimates of soil organic carbon.
Nitrate in stream waters delineates areas of agricultural fertilization. Using data from temporally coincident orthophotography, specific farming practices are related to nitrate pollution.
The EM component identified environmental issues in relation to landfill and saline incursion. Some landfills have little conductivity extending outside their boundaries, while others indicate plumes of increased conductivity are dispersed 500m downslope and suggest leakage. One landfill is coincident with high conductivities (up to 500mS/m) which are interpreted as saline incursion.
Radon levels are extrapolated from geochemical and geophysical methodologies. There is strong correlation between uranium in soil samples and uranium measured radiometrically. The Palaeogene intrusives of the Mourne Mountains are the most radioactive rocks in Northern Ireland and this dataset offers an opportunity to inform the public of radon risk.
137Cs reflects input from Chernobyl and weapons testing. Distribution appears related to the rainfall pattern and redistribution of 137Cs from hilltops into river and stream valleys occurs.
Soil samples (4 per km2) in the cities of Belfast and Londonderry were analysed for both organic and inorganic compounds. In Belfast, elevated Ni and Cr reflect the basaltic geology of the surrounding hills while other elements (Pb, As and Zn) are lower than other industrial cities in the UK. Organic compounds (PAHs) may be related to a diffuse source representing the city’s industrial heritage.