Land Use—Iron Pollution in Mangrove Habitat of Karachi, Indus Delta

Abstract

The coastal area of Karachi, Pakistan, which lies at the northwestern part of the Indus delta, is heavily polluted particularly in the mangrove habitat. The present study traces the pathway of trace metal iron from the source to the different mangrove parts via seawater and sediment. The concentration in the sediment was as high as 34 436 ppm and as low as 0.01 ppm in seawater, while vegetative mangrove parts like pneumatophores, bark, twigs, and leaves possessed generally less than 1000 ppm. The concentration factor (CF) of mangroves was very low, indicating minimum bioavailability of iron from the sediment. The concentration of the metal decreases progressively through different sections of the mangrove habitat in the following sequence: from sediment to pneumatophores to bark to leaves to twigs to seawater.