Muhammad Asif and Salman Saeed
Plant species such as Thlaspi caerulescens Viola calaminaria, Euphorbia prostrata, Arundo donax, Brassica
juncea, Helianthus annuus, Festuca arundinacea, Populus species etc. are long known for their ability to extract
heavy metals from soil and waste water. Various attempts at increasing efficiency of extraction by phytoremediation
include adding micro- organisms, co-cropping various species and using genetically engineered species. So far, the
effect of levels of concentration of heavy metals on extraction efficiency of these plants has not been investigated.
The purpose of this study is to test for the hypothesis that the concentration of heavy metals in soils affects the
efficiency of phytoremediation. Nine samples of Typha latifolia were planted under controlled environment. Plants
were irrigated by wastewater of industrial effluents diluted with different amounts of clean water, while providing
protection from rainwater. The soil in the planters was tested for heavy metals to obtain levels of contamination
already present in the soil and after plants was fully grown, using X-Ray Fluorescence Spectrometry, while the
wastewater used for irrigation was tested using Atomic Absorption Spectrometry. The amount of heavy metals
already present in the soil and that introduced by irrigation was compared to the amount left behind in the soil
after maturity of plants, were compared to test the hypothesis. The results suggested that rate of extraction of
heavy metals using phytoremediation was indeed affected by the level of concentration of heavy metals in the soil
and irrigation water, however, owing to the small number of samples, the relationship between extraction rate and
concentration levels could not be established. The study provides enough evidence to support the stated hypothesis
and opens a new avenue of research to optimize the extraction efficiency of Typha latifolia and other species.
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