Thuli and Thuli and Mzingwane Mzingwane catchments’ catchments’

hydrochemistryhydrochemistryImplications for Implications for

risksrisks

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WHY WHY HYDROCHEMISTRYHYDROCHEMISTRY

Aim is to improve water availabilityAim is to improve water availability But quality of water affect the quality But quality of water affect the quality

Human healthyHuman healthy crops health crops health Livestock healthLivestock health

Thus starting point for any improvement Thus starting point for any improvement in human health & agricultural in human health & agricultural productivity increasing/retaining the productivity increasing/retaining the right quality of water. right quality of water.

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Scope of this workScope of this work

Determination of hydrochemistry Determination of hydrochemistry to to provideprovide Baseline dataBaseline data Water quality risk assessmentWater quality risk assessment

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Study areaStudy area

Zhulube river basin

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MethodsMethods 36 Surface water (SW) and Groundwater 36 Surface water (SW) and Groundwater

(GW)(GW) SW= rivers and dams,SW= rivers and dams, GW= borehole samples from alluvial GW= borehole samples from alluvial

aquifers. aquifers. Analysed at National Water Quality Analysed at National Water Quality

Laboratory, Harare. Laboratory, Harare. Analysed for cadmium, copper, iron, Analysed for cadmium, copper, iron,

manganese, nickel, arsenic, zinc, calcium, , manganese, nickel, arsenic, zinc, calcium, , potassium, sodium, magnesium, potassium, sodium, magnesium, nitrate,nitrite, chloride, phosphate, nitrate,nitrite, chloride, phosphate, sulphate, alkalinity, total dissolved solids sulphate, alkalinity, total dissolved solids and pH. and pH. 6/16/2009

MethodsMethods

pH and electrical conductivity – electrodespH and electrical conductivity – electrodes As, Cd, Ca, Cu, Mg, Mn, Ni, K, Na Zn - As, Cd, Ca, Cu, Mg, Mn, Ni, K, Na Zn -

AAS AAS Fe, nitrate, nitrite and phosphate -Ultra-Fe, nitrate, nitrite and phosphate -Ultra-

violet spectrophotometry. violet spectrophotometry. Chloride, alkalinity and total hardness – Chloride, alkalinity and total hardness –

titrationtitration total dissolved solids - gravimetry. total dissolved solids - gravimetry. Sulphate - turbidimetric method.Sulphate - turbidimetric method.

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Sample location and Sample location and GeologyGeology

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Transition MetalsTransition Metals

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Alkali and alkali earth Alkali and alkali earth metalsmetals

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Non- metalsNon- metals

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ParametersParameters

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Transition metals in SW Transition metals in SW vs GWvs GW

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Alkali metals in SW vs Alkali metals in SW vs GWGW

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Anions in SW vs GWAnions in SW vs GW

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Parameters in SW vs GWParameters in SW vs GW

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Risks to human healthRisks to human health

Cd in GW and SW Throughout the Cd in GW and SW Throughout the two sub catchmenttwo sub catchment

Nitrates – GW- LocalisedNitrates – GW- Localised Manganese –SW - LocalisedManganese –SW - Localised

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Risks to livestock and Risks to livestock and CropsCrops

Chloride ( livestock) –GW- Localised Chloride ( livestock) –GW- Localised Iron ( crops)- GW- LocalisedIron ( crops)- GW- Localised

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Aesthetic and Taste Aesthetic and Taste

Manganese – GW & SW- throughoutManganese – GW & SW- throughout Iron -SW- localisedIron -SW- localised TDS- GW- LocalisedTDS- GW- Localised TH- GW- LocalisedTH- GW- Localised

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Comparison to other Comparison to other catchmentscatchments

Similar results Zhulube catchment Similar results Zhulube catchment (Tunhuma) (Tunhuma)

Hg noted in Zhulube not analysed in this Hg noted in Zhulube not analysed in this studystudy

Lesser sites contaminated than Moza Lesser sites contaminated than Moza (Chilundo)(Chilundo)

Zn, Cu, Fe, Na+, Ca2+, Mg2+ noted in Zn, Cu, Fe, Na+, Ca2+, Mg2+ noted in Moza not a problem in study areaMoza not a problem in study area

As & Se noted in S.A not analysed in the As & Se noted in S.A not analysed in the two sub catchmentstwo sub catchments

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RecommendationsRecommendations

Follow up Cd problem (different lab)Follow up Cd problem (different lab) Establish source of Cd (natural vs Establish source of Cd (natural vs

pollution)pollution) Establish threshold limits for the Establish threshold limits for the

communities associatedcommunities associated Hg not analysed due to costs need to be Hg not analysed due to costs need to be

followed up as it was picked in Zhulubefollowed up as it was picked in Zhulube Encourage responsible farming so that the Encourage responsible farming so that the

quality of water does not deteriorate quality of water does not deteriorate furtherfurther

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THANK YOUTHANK YOU

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