The effects of temperature, salinity and seagrass species on the uptake of lead(II) from seawater by excised leaves

The dynamics of uptake by the leaves of seagrass species has been investigated by ²¹⁰Pb radiotracer techniques. The uptake of Pb from aqueous media per unit area of leaf by the seagrass Zostera muelleri was found to depend on temperature and salinity. Uptake was positively correlated with temperature. Pb uptake was greatest in distilled water and least in salinities exceeding normal seawater. The profile of uptake varied only slightly between three of the species studied, namely Zostera muelleri, Heterozostera tasmanica and Halophila australis, however, uptake by Lepilaena cylindrocarpa was considerably less than the other three species. The variations were examined in relation to microscopic anatomy especially in relation to the epidermis. The results are discussed in relation to possible mechanisms of the uptake of Pb by seagrass leaves. The results are consistent with the view that the seagrass leaves act as passive ion-exchange media during the course of Pb uptake.