Thanks Simis Sir.

Can you please tell me if I have total pigment absorption, then how it can be decomposed in absorption of Chl-a and absorption of PC?

Thanks Simis Sir. Can you please suggest that the realistic concentrations of phycocyanin (PC) and Chl-a in Coastal Case 2 waters?

Thank you very much.

Stephan's method is good but I did a different approach during my M.S. research. To me it would be interesting to compare the methods.

We extracted the pigment and were able to examine the extracted phycocyanin suspension using a spectrophotometer. We determined the a*pc by dividing the absorption by the spectrophotometer by the quantified phycocyanin using florescence. You do need to have fairly large > 20 mg/m3 concentrations for this method to work since the signal to noise ratio is fairly low. I can send you the paper if you do not have access to it at your institution.

Nguy-Robertson et al. 2013. Determination of absorption coefficients for chlorophyll a, phycocyanin, mineral matter and CDOM from three central Indiana reservoirs. Journal of Great Lakes Research. 39:151-160. DOI:10.1016/j.jglr.2013.04.004

Thanks for your answer, but I want to decompose the pigment absorption in absorption by Chl-a, Chl-b, Chl-c as well as absorption for PC. As Stephan's suggested to try a curve fitting method, It looks good for me. If you have different idea to do that. Please suggest me.

Surya, if you are interested in decomposing pigment absorption for all variants of chlorophyll, then Stefan's method is better. The method in my paper is examining extracted pigments in a spectrophotometer. Since the solvent used in extraction will extract all similar pigments, we did not separate the chlorophyll. An additional step such as chromatography would be necessary to separate the variants. I wanted to do this for my study; however, the HPLC we had access to did not have a cooler and my samples degraded over time.

Stefan, the pigment packaging effect should be eliminated in the method presented by our research group since we are worked with extracted samples. This is one possible reason our a*pc values were lower than yours. However, I do concur there are other problems associated with our method (signal to noise was the most problematic). We also assumed that our samples did not contain phycoerythrin because the method technically would extract all phycobiliproteins (same problem as listed in my response to Surya).

Currently my research has taken me towards vegetation. Perhaps when I find a more permanent position I could explore comparing these methods.

Thank you Stefan and Anthony.

Can you suggest me how the phycocyanin back scattering affect the remote sensing reflectance spectra?

Surya,

There are a variety of 'fitting' routine. You can use a sum of Gaussian (works by Hopfner, Moisan), you could do a derivative analysis (e.g. Millie's work on detecting harmful algal bloom). Others (Roesler) use sums of lab/field spectra of specific phytoplankton groups. Good luck!

Thanks Emmanuel Sir. I will try your suggested fitting methods.

Sincerely,

Surya Prakash

For a line-height approach, look at: Kalenak, David, Emmanuel Boss, and Steven W. Effer, 2013. Inherent optical properties of suspended particulates in four temperate lakes: application of in situ spectroscopy. Hydrobiologia, doi 10.1007/s10750-013-1498-5.

Surya,

Sorry for responding so late to your question in October, but for my research we did not separate backscatting from phycocyanin from total backscattering. We did buy a hydroscat my final year on the project with bands at 620 nm to estimate this backscattering in the field; however, I never published this data and I am not sure if anyone in my former group has either. Probably an unsatisfactory answer but perhaps you can answer this in the future.