We mostly use methylene blue or fluorescein, but you may consider this article:

http://akasha.wsu.edu/~flury/theses_articles/dyereview.pdf

Regards

Thank you a lot! I was looking for some reliable informations about fluorescin, the area is protected, so we really care about safety issues. Can you tell me how much of the substance must be dissolved in 1m^3 of water?

I've used rhodamine WT in settings where drinking water supply was a consideration. Rhodamine WT can be detected using fluorescence at very low concentrations, and WT (not B) is not toxic at useful concentrations.

I am confused about what does useful concentration mean. Could you tell me how much Rhodamine WT I need to see results in 1 m3 of water?

I think the general answer to your question would be "no more than needed". The detection limit for fluorescein/uranine is in the low ppb range in fluorescence spectroscopy, and I assume you want to be able to reliably detect it throughout your experiment. The Na salt of fluorescein (its name is uranine) has a solubility of approximately 500 g/L water, which probably will suffice. If you have a rough idea about your flows you might be able to calculate amount or concentration of uranine needed in your situation. Anyway, I recommend to check your detection limits before you start.

You also may search for uranine pictures or videos on google to see some examples how people use it.

Some toxicity data for uranine (no warranty!!):

Oral LD50 (rats): 6721 mg/kg

aquatic toxicity:

EC50 (Daphnia) 337 mg/L (48 h)

LC50 (fish): 1372 mg/L (96 h)

source: MSDS

Thank you Thomas! That is exactly what I have been looking for. We will check everything in lab before using.

Hi there,

one of the most useful non-toxic tracers is a silpho rhodamine B (CI Acid red 87). I used it, and actually worked well. Also, I attach some comments about ir and other tracers. I hope this help.

Katarzyna, as Thomas F suggested, fluorescent dyes are measurable at very low concentrations. Fluorescence requires somewhat more sophisticated measurement methods (an in-situ or lab fluorometer tuned to the right wavelengths) than spectrophotometric (light absorption) methods, but as a result, is much more sensitive and relatively immune from interference from other substances in the water. Rhodamine WT can be clearly detected by fluorescence at concentrations well less than 5 parts per billion, or 5 mg/m3 of water, or 5 ug/L. In our study in an open water channel, we were still getting clear Gaussian dispersion peaks, with large signal-to-noise, at 5 ppb. We used Turner Inc. SCUFA submersible recording fluorometers "tuned" to the rhodamine wavelengths (other filter combinations are for chlorophyll-a, etc.). We made a visual illustration of dilute solutions in glass flasks; 100 ppb was a faint pink color, lower concentrations were hard to detect visually. The MSDS says rainbow trout fish toxisity LC50 >320 mg/l (96 hr), implying that the LC50 was somewhere higher than that; 320 mg/l may have simply been the maximum concentration they tested. LC50 for Daphnia magna is listed as 170 mg/L. ~100mg/L divided by 5 ppb would provide a dilution ratio of 20,000. If you don't need that much sensitivity, and/or don't have access to fluorescence instruments, spectrophotometry might be sufficient.

For your questions on what tracer you can use and for the estimation of tracer injection mass i recommend you the book: Tracers in Hydrology 2009 Leibundgut et al.

I hope this helps!