Iodine in the U.K. environment with particular reference to agriculture.
The iodine content of the top 15 cm of 132 soils formed from a variety of parent materials within the UK ranged from 0.5 to 98.2 mu g g-1 on a dry weight basis. The mean was 9.2 mu g g-1. The highest content occurred in a fen peat soil and the lowest in a podsolized sand. With the exception of two peat soils, the range in content was 0.5-36.9 mu g g-1. The results are consistent with evidence that the retention of iodine in soils is due mainly to aluminium and iron oxides and to organic matter.The iodine content of various soil amendments, including sewage sludges, fertilizers and liming materials was also examined. Only Chilean nitrate and a fertilizer based on seaweed, both used to a very small extent in U.K. agriculture, had iodine contents appreciably greater than the average for soils.Lichens from the trunks and branches of trees had much higher contents of iodine than did grasses, suggesting that the atmosphere is potentially an important direct source of iodine for plants.