Chemistry of transpiration water from cattails: a reflection of subsurface concentrations.
In general, the literature assumes transpired water is essentially deionized water. The purpose of this study was to test this assumption. The method was to collect transpiration water from cattails (Typhus Latifolia) and to analyze its dissolved ions. Some studies have recognized that some plants do transpire more than just pure water (Lindberg, Doucette) but a review of the literature did not find chemical analyses of transpiration water. In addition, evaporation of soil water and plant evapotranspiration concentrates selected ion in the local ground water (Barnes). The working hypothesis was that evapotranspiration of plants included dissolved ions. Out second hypothesis was that not only would there be other ions in the evapotranspiration water but that their concentration would change as ions were concentrated in the soil water and then diluted by recharge events.
Transpiration samples were taken at 3-4 day intervals in plastic bags attached to cattails. Out initial measurements (while biologically challenged) conformed that simple plastic bags could collect the transpiration water from plants. The next round of sampling covered a period when the wetland was receiving no rainfall. A large rainfall event then offered and the conductivity graph shows that within a few days the conductivity of the transpiration water dropped significantly. These results indicate that transpiration water does contain dissolved ion and the change in concentration over time may reflect a change in concentration of solutes in the subsurface water.
Mapping the Yellow River watershed near Postville Iowa with fluorescent dye.
In order to map the Yellow River watershed near Postville Iowa, Three types of fluorescent dye were placed in three distinct locations in the watershed. Direct water sampling and activated charcoal packets were used to determine which of the dyes were present in streams, drilled wells, and springs. Using this knowledge we were able to devise a generalized sketch of the surface and subsurface watershed. In karst landscapes, surface water may disappear in sink holes and stream sinks, later reappearing down gradient at springs. Out study made the connection between three source waters and two main springs.
Mapping watershed in karst landscapes in important on many levels. In areas of heavy agricultural land use, there tend to be higher levels, for instance, nitrates than would be in a "natural" environment. Sources of contamination can be from manure from animals, fertilizers, pesticides, herbicides, soil runoff and waste products in agriculture processing plants. Monitoring where these waste products are traveling and knowledge of the mechanisms and timing of how they get there are important for water resource management. In case of accidental spill of contaminates into a water system, remediation can be much faster and more effective when the transport pathways are known.