1. Dep. of Earth and Environmental Sciences; Univ. of Waterloo; 200 University Ave. W. Waterloo ON N2L 3G1 Canada
2. Environment Lab., Natural Resources Canada; 555 Booth St. Ottawa ON K1A 0G1 Canada
3. Petros GeoConsulting Inc.; 2929 Ester Dome Rd. Fairbanks AK 99709