Pistia stratiotes Distribution in Njaba River: An Implication of Heavy Metals in Surface Water and Sediments

Abstract

The study assessed the effect of heavy metals on the species of higher aquatic plant, Pistia strtiotes in Njaba River, Imo State, Nigeria. Water and higher aquatic plants sample were collected from three stream points (upstream, midstream and downstream) along the course of the River for six months. The following metals were measured: concentration of manganese, Zinc, Iron, Copper, Chromium, Cadmium, Nickel, Lead, Mercury, Arsenic and pH value. Metal pollution index was also used to determine the effect of heavy metals on phytoplankton population. At the end of the study, Nickel, Iron, Cadmium, Lead, Manganese, Arsenic, Mercury, Chromium and Copper concentrations were higher than the permissible value of NSDWQ, 2007 (Nigerian Standard for Drinking Water Quality). The result also revealed that Pistia stratiotes were found more on the midstream (32) and downstream (17) while (3) were found on the upstream. This means that upstream contains more of the heavy metals and so supports little existence of higher plants.