Potential of aquatic plant species as phytoindicators for heavy metal contaminants

Abstract

This research explores the potential of specific aquatic plant species to be used as water quality indicators for unhealthy aquatic ecosystem. The success in the economic growth and industrialization in Malaysia has led to environmental problems with ever-increasing land, air, and water pollution. Industrial production without adequate regard for environmental impacts has increased water and air pollution, and has led to soil degradation and large-scale global impacts such as acid rain, global warming, and ozone depletion. These kinds of pollutions led to many environmental impacts to living organism especially in human daily life. Aquatic plants are emergent, submerge, or floating. They are beneficial to aquatic ecosystem because they provide shelter for flora and fauna, produce oxygen, which assists with overall lake functioning, and provide food for fish and wildlife. The absence of aquatic plants may also indicate water quality problems as a result of excessive nutrients, herbicides or heavy metals and may interfere with lake functioning. In this study, ten samples of water were collected from four different places where six different aquatic plant species were abundance and dominant. For the determination of metals in water, samples were treated according to (American Public Health Association, American Water Works Association, Water Environment Federation, 1999) method and analysed by atomic absorption spectrometry for six types of heavy metals which are iron (Fe), lead (Pb), copper (Cu), zinc (Zn), and nickel (Ni) and manganese (Mn). Results showed that the abundance of certain aquatic plant species indicate high concentration of certain heavy metal in that particular environment. Some of the concentration of heavy metal are exceeded the limits of recommended range INWQS. All were found as good ecological indicators for heavy metal contaminants either at low or high level. Analysis of heavy metals contaminants from four different locations and six different aquatic plant species which are Eichhornia crassipes, Hydrilla verticillata, Cabomba fuscata, Salvinia natans, Nelumbo nucifera and Pistia stratiotes exhibiting highly significant differences (P < 0.0001) between aquatic plant species widespread, locations and the heavy metals content. This clearly demonstrates that freshwater environment with abundance of invasive aquatic plant species can have an important influence and indication on the accumulation of heavy metals content. The importance of the interaction components emphasises that the changes in heavy metals composition are complex and the responses are not consistent across all aquatic plant species. Examination of the summarised data revealed that, of the six species analysed at all different locations, all exhibits as potential ecological indicators for unhealthy aquatic ecosystems or as phytoindicator for heavy metal contaminants either at low or high level contamination. The best phytoindicators for excess iron were C. fuscata> S. natans> N. nucifera. Meanwhile, magnificent phytoindicators for excess Pb were E.crassipes> S.natans> N.nucifera. In addition, good phytoindicators for zinc were E.crassipes> N.nucifera> S.natans. The best phytoindicator for excess copper were S.natans> C.fuscata> E.crassipes. Meanwhile, magnificent phytoindicators for excess manganese were E.crassipes> S.natans> N.nucifera. Lastly, good phytoindicators for nickel were E.crassipes> S.natans> N.nucifera. In conclusion, the most reliable phytoindicators for overall experiment were E.crassipes, S.natans and N.nucifera. Therefore, macrophyte is effective in responding heavy metal in low level environmental contamination that might otherwise be difficult to detect.