Lichen, moss and peat control of C, nutrient and trace metal regime in lakes of permafrost peatlands.

Permafrost thaw in continental lowlands produces large number of thermokarst (thaw) lakes, which act as a major regulator of carbon (C) storage in sediments and C emission in the atmosphere. Here we studied thaw lakes of the NE European permafrost peatlands - shallow water bodies located within frozen peat bogs and receiving the majority of their water input from lateral (surface) runoff. We also conducted mesocosm experiments via interacting lake waters with frozen peat and dominant ground vegetation - lichen and moss. There was a systematic decrease in concentrations of dissolved C, CO2, nutrients and metals with an increase in lake size, corresponding to temporal evolution of the water body and thermokarst development. We hypothesized that ground vegetation and frozen peat provide the majority of C, nutrients and inorganic solutes in the water column of these lakes, and that microbial processing of terrestrial organic matter controls the pattern of CO2 and nutrient concentrations in thermokarst lakes. Substrate mass-normalized C, nutrient (N, P, K), major and trace metal release was maximal in moss mesocosms. After first 16 h of reaction, the pCO2 increased ten-fold in mesocosms with moss and lichen; this increase was much less pronounced in experiments with permafrost peat. Overall, moss and lichen were the dominant factors controlling the enrichment of the lake water in organic C, nutrients, and trace metals and rising the CO2 concentration. The global significance of obtained results is that the changes in ground vegetation, rather than mere frozen peat thawing, may exert the primary control on C, major and trace element balance in aquatic ecosystems of tundra peatlands under climate warming scenario.

Ni(II), Co(II), Cu(II), Zn(II) and Na(I) complexes of a hybrid ligand 4'-(4'''-benzo-15-crown-5)-methyloxy-2,2':6',2''-terpyridine.

Eleven complexes of a hybrid ligand 4'-(4'''-benzo-15-crown-5)-methyloxy-2,2':6',2''-terpyridine (L) were synthesized and characterised by elemental analysis, IR-spectroscopy and X-ray analysis. The crystal structures of seven complexes were determined either from single-crystal data ([NaNCS.L] (6)and [CuL2.NaNCS.Na(NCS)2]+.NCS-.CH3CN) (11) or from powder diffraction data ([CoL2]2+.2NCS- (5) and [ML2]2+.2PF6-.nEtOH.mH2O, M = Ni(II) (1), Co(II) (2), Cu(II) (3), Zn(II) (4)) and revealed good coordinating properties of the ligand L and structural diversity of the obtained compounds. In compounds 1-5, the pi-pi interactions between pyridine rings or between pyridine and benzene rings play an important role in association of the cations.

Synchrotron powder diffraction in a systematic study of 4'-[2-(tosylamino)benzylideneamino]-2,3-benzo-15-crown-5 complexes.

The crystal structures of two compounds, CuL(2) and LiNCS.HL [HL = 4'-[2-(tosylamino)benzylideneamino]-2,3-benzo-15-crown-5], have been determined from synchrotron powder diffraction data. Both compounds crystallize in the monoclinic space group P2(1)/c and with one molecule in the asymmetric unit. In CuL(2) the four N atoms of two bidentate L ligands coordinate the Cu(II) ion in a distorted tetrahedral geometry with Cu-N distances of 1.98 (5)-2.05 (5) A, while two O atoms from two sulfoxide groups complete the distorted octahedral Cu coordination [Cu-O 2.64 (4), 2.74 (4) A]. In LiNCS.HL, lithium is coordinated by all five ether O atoms with Li-O distances of 2.03 (3)-2.50 (3) A and an N atom from the thiocyanate moiety [Li-N 1.98 (3) A] in a distorted pentagonal pyramidal geometry. Preliminary potentiometric selectivity measurements for ion-selective electrodes (ISEs) based on CuL(2) and ZnL(2) demonstrated significant differences in their selectivity. In order to find a possible reason for this, theoretical calculations at the DFT (B3LYP) level were performed. These calculations used the crystal structures of CuL(2), LiNCS.HL, ZnL(2) and HL as input geometries for the minimum energy optimization in vacuo. The results indicate that in ML(2) complexes (M = Cu, Zn) the electronic structure of the metal ion determines the spatial orientation of benzo-15-crown-5 macrocycles, and their different orientation in CuL(2) and ZnL(2) results in different potentiometric selectivities of ISEs based on these compounds.