Improving the accuracy of δ O and δ O values of O measured by continuous-flow isotope-ratio mass spectrometry with a multipoint isotope-ratio calibration.

Rationale: Stable isotope analysis of O is a valuable tool to identify O -consuming processes in the environment; however, reference materials for O isotope analysis are lacking. Consequently, a one-point calibration with O from ambient air is often applied, which can lead to substantial measurement uncertainties. Our goals were to develop a simple multipoint isotope-ratio calibration approach and to determine measurement errors of δ O and δ O values of O associated with a one-point calibration.

Exploring the low photosynthetic efficiency of cyanobacteria in blue light using a mutant lacking phycobilisomes.

The ubiquitous chlorophyll a (Chl a) pigment absorbs both blue and red light. Yet, in contrast to green algae and higher plants, most cyanobacteria have much lower photosynthetic rates in blue than in red light. A plausible but not yet well-supported hypothesis is that blue light results in limited energy transfer to photosystem II (PSII), because cyanobacteria invest most Chl a in photosystem I (PSI), whereas their phycobilisomes (PBS) are mostly associated with PSII but do not absorb blue photons.

Urban wastewater treatment by Tetraselmis sp. CTP4 (Chlorophyta).

The ability of a recent isolate, Tetraselmis sp. CTP4, for nutrient removal from sewage effluents before and after the nitrification process under batch and continuous cultivation was studied. Biomass productivities in both wastewaters were similar under continuous conditions (0.