Combined raman elastic-backscatter LIDAR for vertical profiling of moisture,aerosol extinction,backscatter, and LIDAR ratio

A combined Raman elastic-backscatter lidar has been developed. A XeCl excimer laser is used as the radiation source. Inelastic Raman backscatter signals are spectrally separated from the elastic signal with a filter or grating polychromator. Raman channels can be chosen to register signals from CO₂, O₂, N₂, and H₂O. Algorithms for the calculation of the water-vapor mixing ratio from the Raman signals and the particle extinction and backscatter coefficients from both elastic and inelastic backscatter signals are given. Nighttime measurements of the vertical humidity distribution up to the tropopause and of particle extinction, backscatter, and lidar ratio profiles in the boundary layer, in high-altitude water and ice clouds, and in the stratospheric aerosol layer are presented. Daytime boundary-layer measurements of moisture and particle extinction are made possible by the improved daylight suppression of the grating polychromator. Test measurements of the CO₂ mixing ratio indicate the problems for the Raman lidar technique in monitoring other trace gases than water vapor.     

Determination of the complex stability of zinc with carbonic anhydrase in sea-water.

Carbonic anhydrase (CA) is inactive unless associated with zinc, with possible substitution by cobalt. In this work, the complexation of zinc by CA was determined in sea-water using cathodic stripping voltammetry (CSV) with ligand competition. The zinc was found to be released from the CA over a period of 3 h when equilibrated with a competing complexing ligand and the complex was re-formed with the CA when zinc was added. A value of 8.90+/-0.27 was found for logK'ZnCA where K'ZnCA is the conditional stability constant for the complex of Zn2+ with CA in pH 8 sea-water. A value for the molecular weight of CA was calculated from its equivalent ligand concentration (in nM) obtained by titrations with zinc at various CA concentrations (1-4 mg l(-1)). The value found (34740 g mol(-1)) for the molecular weight is consistent with values found previously by other methods (29000-31000 g mol(-1)) confirming that the stoichiometry of the complex between zinc and CA is 1:1. This work confirms that the zinc-CA complex is reversible and that the interaction between zinc and CA can be determined using CSV with ligand competition.