| Abstract: | Concentrations of Na, K, Ca, Mg, Fe, Mn, and Zn were determined in polluted estuarine (Western Scheldt) and non-polluted (Eastern Scheldt) salt marsh soil, in the shoot tissue of plants of Spartina anglica and in the excretion of the salt glands of Spartina anglica. Excretion of ions by the salt glands of Spartina anglica was analysed with increasing salinity (0, 300, and 500 mM NaCl) and with increasing values of the redox potential of the salt marsh soil (from ?300 mV to +600 mV). Salt glands of Spartina anglica, growing in containers filled with salt marsh soil in the greenhouse excreted Na-ions at a rate of 1.0–1.8 mmol Na+ g?1 dry wt of the shoot tissue over a period of 18 days implying that about every 6–18 days the amount of Na+ present in the shoot tissue is being removed by the salt glands. The excretion rate of K-ions was 0.02–0.14 mmol g?1 dry wt/18 days. Zinc ions are excreted by the salt glands to such a rate (0.03–0.11 μmol g?1 dry wt/18 days) that every 36–900 days the amount of zinc present in the leaves is removed. There was no relation between excretion of Zn ions by the plants and the concentration of zinc in the soil. The excretion of Fe and Mn is reported and was found to be related to increasing values of the redox potential. |
