Abstract
In our preliminary investigation (J. Japan Soc. Air Pollut., 20, 279-285, 1985), it was considered that the pear leaf damages were caused by the accumulation of iodine which was emitted from a iodine refinery. Therefore, the iodine pollution was examined by the arrangement method of potted pear trees (Pyrus serotina REHDER var. culta REHDER cv. Kosui) at the distances of 0, 0.2, 0.7 and 30 km from the iodine refinery. The appearance of leaf damages and accumulation of iodine in leaves were analyzed.
The leaf damages were observed on the potted pear trees only located in the iodine refinery. The nearer from the iodine refinery, the higher was the iodine concentration of pear leaves. These results showed that the pollution source of iodine was the iodine refinery. The polluted area reached to about 0.7 kilometer from the iodine refinery. It was also found that the iodine of pear leaves was absorbed through the leaf from atmosphere.
The growth of pear shoots was depressed by iodine pollution. The iodine threshold concentration, which included the growth distortion on pear shoots, was estimated to be 6-10 ppm, and that for leaf damages was about 30 ppm in Kosui pear, a sensitive cultivar.
