McClain, Charles (Chuck): Retired NASA GSFC (Project Lead)
Project Funding:
2011 - 2014
NRA: 2009 NASA: Terra and Aqua
Funded by NASA
Abstract:
The primary objective of this proposal is for the Calibration and Validation Office (CVO) to provide analyses of algal pigment samples collected by NASA principal investigators (PIs) supported by the Ocean Biology and Biogeochemistry (OBB) program. The pigment products cover a suite of chlorophylls and carotenoids useful to ocean color research, in particular the validation of data products from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and the Moderate Resolution Imaging Spectroradiometer (MODIS). High performance liquid chromatography (HPLC) pigment analysis is a complicated procedure requiring expert analysis and substantial costs for purchasing, maintaining, and calibrating the equipment. A centralized laboratory can be a cost-effective mechanism for providing consistently high-quality data to multiple PIs and databases, but only if the facility is vigilant in the pursuit of excellence, maintains rigorous quality assurance and control (QA and QC, respectively) procedures as part of a well-documented quality assurance plan (QAP), adheres to stated performance metrics to minimize uncertainties, and is evaluated independently (to detect biases and problems). The latter includes the international SeaWiFS HPLC Analysis Round-Robin Experiment (SeaHARRE), annual intercomparison of duplicate samples with another QA laboratory, including the primary manufacturer of standards. All data products will be distributed with limit of detection and quantitation (LOD and LOQ, respectively) analyses, as well as uncertainty estimates. Research on new methods to improve pigment identification and quantitation with the current CVO approach based on the Van Heukelem and Thomas (2001) method (VHT) will occur in parallel with production analyses. Changes in the procedures used in pigment oceanography are expected, along with improvements in the protocols supporting next-generation satellite algorithms, which require advanced analysis techniques and improved pigment detection. Elevated uncertainties are associated with false positives and negatives, plus poor resolution between co-eluting pairs. Rapid resolution liquid chromatography (RRLC) will be used to improve the separation of pigments, and develop faster methods (which provides more analyst time for alternative detection techniques). Method specifications such as the linear gradient, lag time, flow rate, and column temperature will be modified based on DryLab simulations and adjustments made to improve efficiency. The detection and analysis of pigments difficult to distinguish because of similarity in their spectral absorption properties will be improved through the use of liquid chromatography coupled to mass spectrometry detection (LC-MS). The chemical taxonomy (CHEMTAX) program will be used to evaluate the importance of pigment data quality on CHEMTAX output by comparing the output matrix of existing SeaHARRE QA data with data from methods not validated with a proper QA capability (NV). These data provide insight into a) the level at which uncertainties affect the accuracy of CHEMTAX output, b) the effect of data quality on pigment ratios and, thus, the ultimate phytoplankton community characterization, and c) the uncertainties associated with differences between optically simple and complex waters. The algae culture facility established for isolating pigment standards will be used to evaluate pigment ratios under different light and nutrient regimes for various target locations, i.e., the polar regions and coastal regions.
More details may be found in the following project profile(s):
