Detection of extracellular phosphatases in natural spring phytoplankton of a shallow eutrophic lake (Donghu, China)

The species-specific production of extracellular phosphatases in phytoplankton of a subtropical polymictic take was investigated from March to May 2004. Phosphatase activity was detected directly at the site of enzyme action using the enzyme-labelled fluorescence (ELF) technique. Size fractionation of bulk phosphatase activity (PA), concentrations of soluble reactive phosphorus (SRP), chlorophyll a, and phytoplankton composition were determined in parallel. Phosphatase-positive cells were present in every phytoplankton sample; labelled cells were detected in 33 algal taxa, including many chlorophytes, dinoflagellates and some diatoms, but never among cyanobacteria. We recorded an unusual dinoflagellate bloom (Peridiniopsis sp.), of which similar to 25% of the cells were phosphatase-positive. Several populations were partly phosphatase-positive whenever present, while some other species never showed any activity. The production of extracellular phosphatases was not primarily regulated by ambient P concentrations; algae produced these enzymes even if SRP concentrations were high. Moreover, heterotrophic nanoflagellates most probably contributed to the pool of particle-bound PA in some samples.

Chemical composition and source characterization of spring aerosol over Horqin sand land in northeastern China

IEECAS SKLLQG

Characterization of airborne carbonate over a site near Asian dust source regions during spring 2002 and its climatic and environmental significance

IEECAS SKLLQG

Formation of the Yazi Spring Stream and its significance on tectonics-climate on the northern slope of Kunlun Mountains

IEECAS SKLLQG

MEASUREMENT OF TWO-PROTON CORRELATION FROM THE BREAK-UP OF Al-23

Experiments of Al-23 and Mg-22 radioactive beams bombarding a C-12 target at an energy of 60 similar to 70 A MeV have been performed at the projectile fragment separator beamline (RIPS) in the RIKEN Ring Cyclotron Facility to study the two-proton emission from Al-23 and Mg-22 excited states, respectively. The trajectorie of the decay products, namely Na-21 + p + p from Al-23 and Ne-20 + p + p from Mg-22, are clean identified. The relative momentum and opening angle between two protons in the rest frame of three body decay channels are obtained by relativistic-kinematics reconstruction. The results demonstrate that there are some di-proton emission components from He-2 cluster for the excited Al-23 and Mg-22.

MEASUREMENT OF THE PROTON-PROTON CORRELATION FUNCTION FROM THE BREAK-UP OF Mg-22 AND Ne-20

An experiment of Mg-22 and Ne-20 beams bombarding on a C-12 target at an energy of 60 similar to 70 A MeV has been performed at the RIKEN projectile fragment separator (RIPS)in the RIKEN Ring Cyclotron Facility to study the two-proton correlated emission from Mg-22 and Ne-20 excited states. The two-protons momentum correlation functions have been obtained for Mg-22 and Ne-20, respectively. The trajectories of the Mg-22 decayed products (Ne-20 + p + p) were also measured to get the angular correlations between the two protons in Center of Mass of decaying system by relativistic-kinematics reconstruction. The results exhibit that Mg-22 has the features of He-2 cluster decay mechanism.