Compositional and structural dynamics of dissolved organic matter during cyanobacteria (<em>Microcystis aeruginosa</em>) bloom in Taihu Lake, China.

The lake Taihu algal bloom event season 2007 was followed by high-resolution organic structural spectroscopy. NMR spectra indicated extensive molecular alteration throughout all structural regimes during processing of algal matter into DOC with loss and synthesis of carbohydrates, fundamental alteration of aromatic compounds and progressive formation of carboxyl-rich alicyclic compounds (CRAM). FTICR mass spectra indicated near absence of algal extract molecules in summer DOC, and almost complete transformation of biological metabolite signature within the five consecutive months. Contributions of CHNO molecules to continuous molecular series typical of natural organic matter increased during DOC transformation. The time-dependent individual molecular signature of Lake Taihu DOC is likely dominated by microbial metabolism rather than abiotic chemistry. High-resolution organic structural spectroscopy is clearly capable to resolve meaningful molecular detail out of very complex real environmental mixtures, which has contributed here to expand the description of algal blooms from bulk to molecular resolution