An initial study to assess the use of geological parent materials to predict the Se concentration in overlying soils and in five staple foodstuffs produced on them in Scotland

Evidence suggests that dietary-intakes of the essential element selenium have fallen in Scotland in recent years, due to changing sources of bread-making wheat. The Scottish environment is thought to be Se-poor due to the geology and climate. This initial study assessed whether geological parent-materials could be used to predict relatively high and low soil-Se areas in Scotland and whether differences in soil-Se were reflected in foodstuff-Se produced on them. Samples (n = 8 per farm) of wheat, calabrese (broccoli), potato, beef-steak, milk, cattle pasture (grass) and soil were collected from pairs of farms (one in each high/low predicted Se area (PSA)). Potatoes and soils were collected from a further 34 farms in high/low PSAs to assess a greater geographical zone. Total soil-Se ranged from 0.115 to 0.877 mg kg(-1) but most samples (90%) could be classed as Se-deficient (<0.6 mg kg(-1)), irrespective of PSA. Total soil-Se was significantly higher (p<0.05) in the high than in the low PSAs as expected; however, the difference between the two was small (mean 0.48 and 0.37 mg kg(-1), respectively). Water-soluble soil-Se (6.69 to 26.78 mu g kg(-1)) concentrations were not significantly different between the two PSAs (p = 0.71). Soil loss-on-ignition (indicating organic matter content) correlated significantly with total and water-soluble soil-Se (p<0.001) and exerted a greater control than parent-material on soil-Se. Significant differences between the PSAs for beef-Se (p<0.001), wheat-Se (p<0.001), calabrese-Se (p<0.01) and beef-farm grass-Se (p<0.05) indicated partial success of the parent-material soil-Se prediction. However, only wheat-Se (p<0.001) and potato-Se (p<0.001) correlated significantly with total soil-Se. The results suggest that soil-Se concentrations in the main agricultural areas of Scotland are generally low. Given the low Se concentrations also reported in the food commodities: further investigations may be warranted to fully characterise the Se-status of Scottish produce and dietary-Se intakes in Scotland. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.