A STUDY OF TRANSPORT AND MIXING IN NATURAL-WATERS USING ICP-MS - WATER-PARTICLE INTERACTIONS

Water-particle interactions often may result in non-conservative chemi cal behavior when waters from different sources mix with one another. The results presented in this paper address the role of these interact ions in freshwater and estuarine mixing and support a larger study to develop a method to help resolve flow distribution and water quality q uestions in surface waters using a source water ''fingerprinting'' tec hnique. Inductively coupled plasma-mass spectrometry (ICP-MS) is used to ''fingerprint'' each water source based upon the concentrations and relative proportions of elements in that source. Estimates can then b e made of the fractions of various ''fingerprinted'' waters in water s amples that contain a mixture of source waters. Such estimates depend upon the selection of tracers that behave conservatively during mixing ; in this paper, results to establish the maximum particle exchange ca pacity and conservative mixing behavior are presented for samples coll ected from the Sacramento River-San Francisco Bay-Delta estuary. Eleme nts likely to behave conservatively include boron, sodium, magnesium, potassium, calcium, strontium, and molybdenum.