Die Bodenkultur - Journal for Land Management, Food and Environment
H. Spiegel, G. Zethner, R. Goodchild, M. Dachler and I. Kernmayer:
Cadmium in the Environment – An Austrian review
2nd Report: Soil Balances and Risk Characterisation
Using a dynamic mass balance model the mean, as well as 95 % percentile concentrations of Cadmium (Cd) in Austrian soils, soil water/leachate and Cd leached from Austrian soils were calculated at different times (1 and 100 years) and with different Cd contents of mineral P-fertilisers (25 and 90 mg Cd kg-1P2O5). This shows that when P-fertilisers with the current mean concentration of 25 mg Cd kg-1P2O5 are used, the weighted means of both the Cd concentration in the soil water/leachate and the Cd leached from Austrian soils will increase by 21 % over the next 100 years and the soil Cd content by 46 % over the same time period. Were Austria required to lift its limit value of 75 mg Cd kg-1P2O5 then P-fertilisers with 90 mg Cd kg-1P2O5 could come onto the market. At such a value there would be a 38 % increase in both the Cd concentration in the leachate and the Cd leached from Austrian soils. The Cd content of Austrian soils would increase more significantly – by 81 %.
Most of the soil Cd balances quoted assume that atmospheric deposition is the most important input source of Cd, followed by mineral fertilisers. If regional or field level inputs are taken into account farmyard manure, sewage sludge and solid organic wastes (composts) may also contribute significantly to Cd inputs in soils. Crop offtake and leaching from soil were the most important Cd outputs. Cd concentration in the leachate, and thus leaching, was calculated using the McBride algorithm and, in so doing, also the distribution of Cd between soluble and sorbed phase.
The risk characterisation was done placing special emphasis on Cd in P-fertilisers and showed that despite existing risk reduction measures the mean (and 95 % percentiles) PEC values exceed the PNEC for water. For soils in 5% of the 52 arable regions, the PEC/PNEC ratio is greater than 1 if bioavailable values are used. This means that, according to the EU risk assessment methodology, the substance is “of concern” and further – preferably EU-wide – measures to reduce the Cd input into agricultural soils should be taken.
Key words: cadmium, fertiliser, model, risk characterisation, balances.