About the Water Plots

The water profile plots present a seven day history of the parameters below. The x-axis on each plot displays time, expressed as a day of year, while the y-axis displays depth from the free surface. A colorbar provides a scale for each plot.

Profiles are conducted every four hours starting at twenty minutes past midnight. Samples are taken at one meter increments with transitions between depths taking approximately two minutes. A profile takes slightly over one hour to complete.

 Temperature

 Temperature is a bulk parameter used to track water. As water cools, it becomes more dense down to 4° C, after which density begins to increase (remember, ice floats). Because of this we expect to find cooler water underlying warmer water.

 Because of the change in density of water based on temperature, we often find stratification in the water column. The region where the sharpest temperature changes or gradients occur is generally referred to as the thermocline. The region above the thermocline is referred to as the epilimnion or surface layer. The region containing the thermocline and most temperature change between the surface and bottom the metalimnion. A much deeper region with little temperature change throughout the year is referred to as the hypolimniom. These are descriptive terms only and relate only basic information about the region of interest.

Conductivity/Specific Conductance

 Conductivity is a measure of the ability of water to conduct an electrical current. It is affected by salinity and temperature. Since Cayuga Lake is isohalinic or of constant salinity throughout, temperature is the greatest influence on conductivity in the lake. Temperature and conductivity increase together, allowing the determination of the origin of water since cooler deeper waters will have lower conductivity. Specific conductance is a corrected scale of conductivity, rescaling all measurements to 25° C to allow for a direct comparison.

Turbidity

 Turbidity is an optical measurement of the amount of light scattered or absorbed by suspended matter, both organic and inorganic, in the water. It is reported in Nephelometric Turbidity Units (NTU), a standard based on the measurement technique employed, nephelometry. Turbidity measurements are affected by temperature, but this is compensated for in the measurement technique.

 Turbidity is not a direct measure of the clarity, suspended sediment load, or color or water, it is only a measure of the light scattering abilities of suspended particles in the water. Turbidity can provide an estimate of the Total Suspended Solids (TSS) in the water.

Chlorphyll

 Chlorophyll is an optical measurement of the amount of chlorophyll in the water. As presented here it is not a direct measure of biological activity, but does allow the examination of trends in activity and given other analysis techniques can be correlated to biological activity. It is temperature dependent, with the measured flouresence decreasing with temperature. Chlorophyll itself is a chemical component in photosynthesis and is present in the cells of algae, phytoplankton, and aquatic plants.

Dissolved Oxygen

 Dissolved Oxygen is just that, a measure of the amount of oxygen dissolved in water. It is presented in two forms, as miligrams (mg) of oxygen per liter (L) of water and as a percentage of the saturated value for a given temperature. As temperature decreases, the saturation concentration of oxygen increases. During stratified conditions we expect to see surface waters at or near saturation, and the deeper water to be below saturation values.

PH (currently unavailable)                                                                                            

 pH is a measure of the acidity of a solution. It is defined as the negative logarithm of the concentration of [H+] ions. Values from 1 to 7 are considered strongly acidic to nuetral, values from 7 to 14 are considered nuetral to strongly basic (or alkaline). Cayuga Lake will generally be slightly basic with a pH of about 7.5-8.5 and resists changes in pH because it is buffered by its ionic content.