recommend intern commiss protect rhine pollut supplement annex iv convent protect rhine chemic pollut sign bonn decemb intern commiss protect rhine pollut regard convent protect rhine chemic pollut sign bonn decemb regard articl thereof propos contract parti convent annex iv convent decemb supplement respect mercuri limit valu articl gt pic file quot quot gt pursuant articl convent measur set tabl enter forc unanim adopt contract parti convent contract parti notifi adopt govern swiss confeder acknowledg recept notif