4.1 Each year many thousands of water samples are collected and the chemical components are determined from natural and human-influenced groundwater sources.
4.2 The objective interpretation of the origin, composition, and interrelationships of water can be simplified by displaying the distribution of the constituents and related parameters on areal maps (1,2).4
4.2.1 The origin of the chemical composition of the water may be postulated by the amount and the distribution of the constituents as shown on the maps.
4.2.2 The chemical composition of the water can be scrutinized for distinct characteristics and anomalies by use of the maps.
4.2.3 The interrelationships of the water chemistry from various sampling locations can be visualized on the maps.
4.3 This guide presents various mapping methods for showing distribution of chemical constituents using areal and time-related trends; maximum, minimum, or mean values; and relationships between chemical and associated parameters.
4.4 Exercise caution when interpreting the distribution of chemical constituents on two-dimensional (X and Y) maps as liquids of different densities tend to stratify in the third dimension (Z).
Note 2: Water (or other liquid) with a relatively low concentration of dissolved solids (or of a low relative density) normally will float on top of water with high dissolved solids or a liquid of higher density (3-7). A naturally occurring example is an island surrounded and underlain by sea water where rain water falling on the island forms a fresh water lens above the underlying sea water. Where the presence of liquids of different densities are evident in a mapped area, cross sections of the aquifer assist in showing the vertical (Z) distribution of the chemical constituents or a pattern can be used on the map to delineate the extent of this water.
Note 3: Immiscible liquid contaminants, such as petroleum products, with a relative density less than that of the water will float on top of the water. Liquids that are more dense than water will flow to the bottom of the aquifer. Miscible liquids, such as sea water, mix with the fresher water crea......