Heavy metal contamination has become a significantproblem in several community and agricultural areas over theyears due to the application of commercial agrochemicals onagricultural production 23. However, heavy metalsoriginating from anthropogenic sources have been found inall components of the environment 4, 11, 12. In recentyears, more attention has been devoted to pollutants in theenvironment due to increase in anthropogenic contribution byheavy metals 8, 14. Heavy metals can eventually dispersedand accumulated in the soil as well as surface andgroundwater and may therefore affect adverse human healtheffect to living organisms 6, 22, 24. The InternationalAgency for Research on Cancer (IARC) has categorized Cdand its compounds as group 1 human carcinogen, andclassified inorganic Pb compounds as probably humancarcinogen (Group 2A) and organic Pb as possible humancarcinogen (group 2B) 5. Therefore, human health riskassessment plays significant role inthe process of estimatingthe nature and probability of adverse health effects in humansassociated with the exposure to hazards in contaminatedenvironments 26.Groundwater signifies an important source of drinkingwater, however, its quality might be threatened by a factorssuch as geological variation (such as soil type), water andsoil chemistry.
There are also other anthropogenicalenhancedfactors, which lead to groundwater contaminations.For instances all activities conducted around the drinkingwater sources, onsite leaky septic tanks, and pit latrines. Allthese factors influence the transportation, distribution, andfate of the chemicals, and other contaminants in thegroundwater aquifers 20.As water quality is an environmental determinant ofhealth, the knowledge, and awareness of the quality ofdrinking water remains crucial. The management andsustainability of good drinking water quality is an importantfactor in prevention and control of the waterborne diseases.Thus, the present study highlights the levels of some physicochemicalparameters of groundwater resources along Fuoniarea in Zanzibar Island.
The levels of pH, turbidity, electricalconductivity (EC), total dissolved solid (TDS) and hazardindices were also investigated.While strong positive correlations existed for some of theanalyzed parameters, some negative correlations were alsoobserved. As an example, thallium has shown strong positivecorrelations with magnesium and sodium.
Thalliumrelationship with magnesium and sodium were found to havePearson correlation values of 0.974 and 0.833 respectively(Table-3). The correlation between same parameters is notnecessarily constant, and it can differ remarkably from onestudy area to another.
In the analytical chemistry perspective,the correlation matrix is a fundamental and pervasiveconcept, and it does not necessarily mean the presence ofcausality among the analyzed parameters 19.