Bioscience Methods 2017, Vol.8, No.1, 1-18
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sum of pollution index showed wide range of disparity. This is an indication of seasonal influence. The variation
among the different locations could be due to deviation in topography, making some of the areas more prone to
runoff after rainfall. Furthermore, other anthropogenic activities could also account for variation in the various
locations with regard to sum of pollution index.
Figure 5 Sum of pollution index of heavy metals concentration in cassava mill effluent contaminated soil
From all pollution load indices consider, the study showed that cassava mill effluents in receiving soil are
contributing to slight heavy metals pollution. According to Qiu (2010), heavy metals pollution from industrial
setting typically originates from three sources including exhaust, human activities and secondary pollution. Based
on the various pollution indices under study, the heavy metals resulting from cassava mill effluent is leading to
low/slightly polluted to moderate pollution. This trend has been reported in soil near sugar mill when several
integrated and contamination factors were applied in the assessment of pollution load (Sarala and Sabitha, 2012).
The pollution level based on the different indices used showed variation among the different mills in the study
area. According to Mazurek et al. (2017), Hernandez et al. (2003), heavy metals pollution in soil varies according
to its chemical and physical characteristics including texture, buffering ability and the capacity to neutralize
contaminants. Mazurek et al. (2017), Pajak et al. (2015) also reported that the distribution/arrangement of soil
heavy metals depends on landscape and or/ topography. This could account for minor variation among the various
locations of study.
3 Conclusions
Nigeria is the world leading producer of cassava accounting for over 20% of global output. Cassava processing is
majorly carried out by small-scale processors in the Niger Delta region of Nigeria. During cassava processing,
effluent is produced from the dewatering zone which accounts for about 16% of total cassava tuber weight. This
effluent is toxic to some living things. This study evaluated the pollution load of heavy metals in cassava mill
effluents contaminated soil in rural community in the Niger Delta region of Nigeria. Secondary data from cassava
mill effluents soil were used in this study. Pollution load were considered based on two background scenarios viz:
BGM and BMM. The results revealed low to considerable contamination (CF, API, MPI), low to moderate
contamination (CD, PI/CI), no pollution to moderate pollution (PLI), no pollution to low pollution (PI) and
warning line of pollution to high pollution (NIPI). Therefore, cassava mill effluents from small-scale cassava
processing in the Niger Delta are contributing to heavy metals pollution in the soil which tends to vary according
to seasons.
Acknowledgements
This paper is based on part of PhD project work of S.C. Izah supervised by Dr S.E. Bassey and Prof. E.I. Ohimain at the Niger Delta
University, Wilberforce Island, Nigeria. The dry season data of this study was used for abstract presentation which was selected for
E-Poster at the ―3rd Annual Congress on Pollution and Global warming‖ holding on October 16-18
th
, 2017 in Atlanta, Georgia, USA.
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