The concentrations of arsenic (As), chromium (Cr) and iron (Fe) were determined in the foodstuffs, soils and sediments from various areas in Bangladesh and new data for these toxic trace elements were given. The arsenic pollution problems in the most of the areas of Bangladesh are of geological origin. The high level of As in foodstuffs, soils and sediments, except for tannery sediments is probably positively correlated to the Fe concentration. An excessive amount of chromium was found in the sediments from the tannery area of Bangladesh.

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Three new oxo-centered trinuclear mixed-valence iron complexes, iron succinate, iron mesaconate and iron isophthalate have been prepared. Temperature dependent valence delocalization processes were observed for all the complexes on variable temperature Mö ssbauer spectroscopic studies. Two clear quadrupole split doublets attributed to high-spin Fe(III) and high-spin Fe(II) states were existed for the complexes at liquid nitrogen temperature. At room temperature a nearly averaged singlet peak was observed for mesaconate complex and averaged doublet peaks were observed for succinate and isophthalate complexes with IS values 0.68 and 0.68 mms j1 and QS values 0.44 and 0.48 mms j1 respectively.

The temperature dependence in the