23? ???? ?? ?????? ??? 2?? ???? ??????? 39.5? ??(41.7) ??(48.1) ? ?? 6? ???? ???.

?? ??? ??? ????? ???? ????? ?? ?????? ??? ?? 0.022PPM(??? 0.05PPM), 0.008PPM(〃 0.06〃)?? 7? ?? ??? ?? ???. ? ???????? 0.016PPM(??? 0.03PPM)?? 7??? ? 5??, ????? ?? 71?(??? 1?50?)?? 3?? ?? ????.

??? ‘???? ??’? 93? 7? ?? ??? ?????? 95? 6?, 96? 5?, 97? 3? ??? ??? ?????.

〈??〓?????〉