Introduction: Letter from the Director of Sales & Marketing
In the Spotlight: Cyclops-7 Submersible Fluorometer
Jim's Corner: TD-700 Sensitivity Level
Instruments In Action: Aquarius Undersea Laboratory Utilizes 10AU for Coral Reef Sponge Study
Instruments In Action: Fluorescent Detection of Optical Whiteners & Brighteners
Dye Tracing Highlights: Hydrologic Tracer Tests with the 10AU for Risk Assessment Studies
 

Thank you for taking the time to read the December edition of TD News. We have highlighted several interesting UV fluorescence applications in this issue that we hope you find informative. By 'UV fluorescence' we are referring to applications which utilize UV light as an excitation source (<400nm). The applications include but are not limited to; ammonium, colored dissolved organic matter (CDOM), optical whiteners and brighteners and hydrocarbons. The ammonium fluorescence technique developed in the late 90's has become a very popular and robust technique for low ammonium environments. We highlight a very interesting use of this technique that investigates the effect of marine sponges on the nitrogen cycle. We also highlight a recent use of optical brightener detection that allows users to accurately identify sources of human waste into freshwater and coastal environments. If you have an interest in hydrocarbon detection, please visit the world leaders in the use of fluorescence to detect hydrocarbons at Turner Designs Hydrocarbon Instruments.

In addition to our UV fluorescence pieces we have also included a new section that will focus on various topics related to fluorescent dye tracing techniques. This month's article deals with hydrological techniques developed by the United States. E.P.A. to asses risk for a wide variety of programs.

I hope you enjoy this edition of the TD Newsletter. We are always interested in hearing from you; please do not hesitate to contact us with feedback on the newsletter or our products and services.

Yours truly,
Rob Ellison
Director of Sales and Marketing

In The Spotlight - Cyclops-7 Submersible Fluorometer

We are ramping up our production of our exciting new line of Cyclops-7 submersible sensors. In our last TD News issue we introduced the Cyclops-7. We have now finalized the data sheet and are collecting data from several instrument installations. The graph below depicts in vivo chlorophyll data collected in San Francisco Bay from a deployment of a Cyclops-7 and SCUFA submersible fluorometer. As you can see the two instruments track extremely well.

The Cyclops-7 is designed for integration into CTD or other multi-parameter systems. It has maintained the sensitivity of the SCUFA while significantly reducing the size, power consumption and cost. For more information on this exciting new sensor please contact our sales team.

For a detailed specification sheet, please click on the following link for the Cyclops-7 data sheet.

Question:
How can I increase the Sensitivity level on the Model TD-700, but still maintain the same reading that my Solid Standard gives?

Answer:
You should use the "Multi-Optional Mode - Direct Concentration" set up. This allows you to define the "Max Range" value. The Max Range value will be the highest value you can read on the TD 700. As you lower the Max Range value, the TD 700 will increase the sensitivity level to achieve the new setting. The higher sensitivity setting will give you better resolution for reading your low samples. The next step in the calibration process asks for the "Hi Std Conc." Value. This is where you will enter the value you desire for your standard to read. For example, if the High position of your Solid Standard had read 120 in the past, then you would enter the value of 120. One thing to note, the Max Range value you use, should be at least 5% higher than your standard value. So for this example you should enter a Max Range value that is higher than 126. After the calibration has completed, you can press the number 8 key on the keypad to verify the Sens. % level. A Sens. % value between 10 and 70 % is preferred for best results.

Aquarius Undersea Laboratory Utilizes 10AU for Coral Reef Sponge Study

Aquarius is an underwater ocean laboratory located in the Florida Keys National Marine Sanctuary. The laboratory is deployed three and half miles offshore, at a depth of 60 feet, next to spectacular coral reefs. Scientists live in Aquarius during ten-day missions using saturation diving to study and explore our coastal ocean. Aquarius is owned by NOAA and is operated by the National Undersea Research Center at the University of North Carolina at Wilmington.

The sponge Callispongia (photo by Chris Martens)

Last September, Aquarius was utilized by a crew of six aquanauts that spent nine days living underwater to study coral reef sponges - an important feature of coral reefs in Florida and throughout the world. This mission is part of a larger research effort to understand the feeding biology of sponges in the Florida Keys, from nearshore (including Florida Bay) to the offshore coral reefs. Sponges are an important part of the coral reef ecosystem, yet surprisingly little is known about their biology and ecology. A major focus of this work is to understand how sponges secure carbon and nitrogen to meet their basic needs of metabolism and growth. In other words, what and how do they eat?

A Chapel Hill diver working on sponges being acclimatized for use in NH4 uptake and release experiments (photo by Chris Martens)

Sponges are animals that make their living on the reef by filtering massive amounts of water to extract bacteria and other fine particles for food. Importantly, recent discoveries have shown that large populations of bacteria live inside some sponge species. The bacteria are hypothesized to have the ability to take dissolved nitrogen gas in seawater and convert it to forms of nitrogen that can be used to help support sponge nutrition. The consequences of these different feeding strategies - filtering or using the products of bacteria - are significant for individual species and for the nutrient budget of the larger reef system.

Since tracking and measuring ammonium was of critical importance to the study, the researchers evaluated the different options available before deciding on the fluorometric method of ammonium measurement utilizing the Turner Designs 10AU Field Fluorometer. This choice was made over the phenol hypochlorite method that the researchers had used in the past. After the study concluded, the researchers were extremely pleased with the quality of the data generated by the 10AU, along with it's relative ease of use. Here is some of the data that they gathered from the 10AU, relating two different sponge species (Aplysina cauliformis and Niphates erecta):

Overall, the researchers on this mission were successful in learning more about the biology and ecology of sponges, especially as it pertains to their role in nitrogen cycling in the oceans. The data gathered shows that certain species can act as nitrogen sources, whereas others can act as nitrogen sinks, and these findings will most likely bring more attention to them in future environmental research. For more details on this mission and other Aquarius research, please visit the following link on their website at: http://www.uncw.edu/aquarius/2003/09_2003/expd.htm

Fluorescent Detection of Optical Whiteners & Brighteners

Jon boat set up to use the 10AU Field Fluorometer. The submersible pump is located on the end of the pvc pipe and water flows through a hose inside the pvc pipe, then through the fluorometer.

A recent project funded by the Virginia Department of Conservation and Recreation and conducted by staff from Virginia Polytechnic Institute and State University involved the use of the fluorescence detection of optical brighteners as a means of identifying leaking septic systems from water-front properties. The system detected three UV fluorescing compounds; fecal sterols, detergent surfactants and optical brighteners. All of these compounds are indicators of human waste. The sources of these compounds had two possible sources in the study area; on-site wastewater systems or leaking pipes from municipal wastewater treatment systems. The 10-AU Field Fluorometer was successfully used to detect and map fluorescent plumes in freshwater and saltwater systems. Click here to view the complete report.

Hydrologic Tracer Tests with the 10AU for Risk Assessment Studies

constant rate injection of the dye

The National Center for Environmental Assessment (NCEA) of the Office of Research and Development (ORD) of the United States Environmental Protection Agency (EPA) conducts hydrologic tracer tests as part of risk assessment conducted for local communities, state environmental programs and EPA regional offices. Hydrological tracer testing is the most reliable diagnostic technique available for establishing flow trajectories and hydrologic connections and for determining basic hydraulic and geometric parameters necessary for establishing operative solute-transport processes all of which as essential to the development of sound risk assessments.

adding two dyes as a slug injection

Malcolm Field is the principle scientist conducting the tracer tests. He uses Model 10-AU-005 fluorometers to obtain real-time fluorescence data at an appropriately calculated frequency such that the tracer-breakthrough curve (BTC) is sufficiently defined so that data aliasing is minimized. The mass of tracer to release and the sampling frequency are calculated by the recently developed computer program, EHTD, and the resulting BTC is processed using the program, QTRACER2, both of which were developed at NCEA. To facilitate data processing of data automatically logged by a Model-10-AU-005 by QTRACER2, a new program, FLOWTHRU, is currently under development at NCEA. FLOWTHRU quickly and efficiently converts logged data to decimal time units, allows for time breaks in the data, and automatically plots the data so that data trends may be observed. The converted data may then be copied to a QTRACER2 station data file for BTC analysis.

two 10AU's set up for rhodamine & fluorescein dye detection

Most recently, two Model 10-AU-005 fluorometers were deployed at a major production well in Poolesville, Md. where coliform contamination has become a problem in recent years. Preliminary tracing by the Maryland Department of the Environment (MDE) suggested that nearby solid waste sewers might be leaking which requires well abandonment. However, more rigorous tracer testing by EPA and MDE provided evidence that the sewers are intact and that the source of the coliform contamination is not the sewers. The source of the coliform contamination remains an unknown and will perhaps require more comprehensive tracer testing from other potential source areas. Once the source area(s) is(are) established the tracing data can be used to facilitate a detailed risk assessment for the well head and appropriate actions taken.

Similar efforts are being played out in a number of communities. NCEA continues to provide as timely and inexpensive testing as possible to local communities so that limited resources can be dedicated to resolving the problems uncovered.