ABSTRACT
The crystal and mol-ecular strutures of two solvated forms of [K(18c6)]OAc (18c6 = 18-crown-6 = 1,4,7,10,13,16-hexa-oxa-cyclo-octa-decane and OAc = acetate) were determined by single-crystal X-ray diffraction, namely (acetato-κ2O,O')(1,4,7,10,13,16-hexa-oxa-cyclo-octa-decane-κ6O)potassium dihydrate, [K(CH3COO)(C12H24O6)]·2H2O (1) and (acetato-κ2O,O')aqua-(1,4,7,10,13,16-hexa-oxa-cyclo-octa-decane-κ6O)potassium acetic acid monosolvate [K(CH3COO)(C12H24O6)(H2O)]·CH3COOH (2). In both compounds, the acetate anion is bonded to the potassium ion in a chelating fashion and the metal atom is consequently slightly displaced from the O6 plane of the crown ether. In the crystals, O-Hâ¯O hydrogen bonds lead to a polymeric ladder structure in the dihydrate 1, while the acetic acid hydrate 2 features inversion dimers.
ABSTRACT
The surficial coastal sediments in Kendari Bay are sampled in the field to determine the concentration and pollution level of three heavy metals (Pb, Cd and Cr). Twenty-five sampling points ranging from the inner (Wanggu River) to the outer area of the bay have been chosen. The physicochemical properties, such as temperature, pH, salinity and TDS of the overlying water, as well as the sediment type and TOC of the surficial sediments, are also measured. The total concentrations of the Pb, Cd and Cr in the sediment samples are quantified using inductively-coupled plasma mass spectrometry (ICP-MS). The concentrations of the heavy metals (Pb, Cd and Cr) ranged from 0.84 to 17.02 µg/g, 0.02 to 0.17 µg/g and 1.92 to 40.11 µg/g (dry weight), respectively, following the Cr>Pb>Cd sequence. To assess the degree of contamination, a geoaccumulation index (Igeo) is measured. Kendari Bay is not a contaminated area regarding Pb, Cd and Cr.
