Artificial seawater, solution studies

Working solutions (1 litre) which were 10 7 mol/1 in one of the elements to be studied were prepared by appropriate addition of the radioactive stock solutions to pH-adjusted artificial seawater. After the pH had been checked, 100 ml portions were transferred to the bottles to be tested. The filled bottles were shaken continuously and gently in an upright position, at room temperature and in the dark. At certain time intervals, ranging from 1 min to 28 d, 0.1 ml aliquots were taken. These aliquots were counted in a 3 x 3 in Nal (TI) well-type scintillation detector, coupled to a single-channel analyser with a window setting corresponding to the rays to be measured. 

McCubbin, D. and Leonard, K.S. (1997) Laboratory studies to investigate short-term oxidation and sorption behaviour of Np in artificial and natural seawater solutions. Mar. Chem., 56, 107-121. 

The emf data for cell A can be used to establish standard reference values of (pMh)s in the buffer solutions studied, where the unit of Mh is moles of free H" /kg of seawater. With the use of these standards in a form of Equation 6 (with pMn written in place of pmn), experimental values of (pMn)x in artificial seawater of about 35%o salinity (and hopefully also in natural seawater of the same salinity) can be obtained. These standard values are Hsted in Table VII. 

The stability of Pu(Vl) and Pu(V) was studied in solutions of standard artificial (same mineral constitution) seawater and of true seawater from the Gulf of Mexico (collected ca. 5 miles from the Florida coastline below Tallahassee). All solutions were buffered to pH 8.0 by addition of trishydroxymethylaminomethane ("tris") and filtered by vacuum through 0.45 micron Millipore filters. The glassware, pipets, etc. used were treated to reduce adsorption losses of Pu at pH 8 by a method developed in this laboratory (10). 

---