Thuli and Mzingwane catchments’ hydrochemistry Implications for risks Thuli and Mzingwane catchments’ hydrochemistry Implications for risks 6/16/2009

WHY HYDROCHEMISTRY Aim is to improve water availability Aim is to improve water availability But quality of water affect the quality But quality of water affect the quality Human healthy Human healthy crops health crops health Livestock health Livestock health Thus starting point for any improvement in human health & agricultural productivity increasing/retaining the right quality of water. Thus starting point for any improvement in human health & agricultural productivity increasing/retaining the right quality of water. 6/16/2009

Scope of this work Determination of hydrochemistry to provide Determination of hydrochemistry to provide Baseline data Baseline data Water quality risk assessment Water quality risk assessment 6/16/2009

Study area 6/16/2009

Methods 36 Surface water (SW) and Groundwater (GW) 36 Surface water (SW) and Groundwater (GW) SW= rivers and dams, SW= rivers and dams, GW= borehole samples from alluvial aquifers. GW= borehole samples from alluvial aquifers. Analysed at National Water Quality Laboratory, Harare. Analysed at National Water Quality Laboratory, Harare. Analysed for cadmium, copper, iron, manganese, nickel, arsenic, zinc, calcium,, potassium, sodium, magnesium, nitrate,nitrite, chloride, phosphate, sulphate, alkalinity, total dissolved solids and pH. Analysed for cadmium, copper, iron, manganese, nickel, arsenic, zinc, calcium,, potassium, sodium, magnesium, nitrate,nitrite, chloride, phosphate, sulphate, alkalinity, total dissolved solids and pH. 6/16/2009

Methods pH and electrical conductivity – electrodes pH and electrical conductivity – electrodes As, Cd, Ca, Cu, Mg, Mn, Ni, K, Na Zn - AAS As, Cd, Ca, Cu, Mg, Mn, Ni, K, Na Zn - AAS Fe, nitrate, nitrite and phosphate -Ultra-violet spectrophotometry. Fe, nitrate, nitrite and phosphate -Ultra-violet spectrophotometry. Chloride, alkalinity and total hardness – titration Chloride, alkalinity and total hardness – titration total dissolved solids - gravimetry. total dissolved solids - gravimetry. Sulphate - turbidimetric method. Sulphate - turbidimetric method. 6/16/2009

Sample location and Geology 6/16/2009

Transition Metals 6/16/2009

Alkali and alkali earth metals 6/16/2009

Non- metals 6/16/2009

Parameters

Transition metals in SW vs GW 6/16/2009

Alkali metals in SW vs GW 6/16/2009

Anions in SW vs GW 6/16/2009

Parameters in SW vs GW 6/16/2009

Risks to human health Cd in GW and SW Throughout the two sub catchment Cd in GW and SW Throughout the two sub catchment Nitrates – GW- Localised Nitrates – GW- Localised Manganese –SW - Localised Manganese –SW - Localised 6/16/2009

Risks to livestock and Crops Chloride ( livestock) –GW- Localised Chloride ( livestock) –GW- Localised Iron ( crops)- GW- Localised Iron ( crops)- GW- Localised 6/16/2009

Aesthetic and Taste Manganese – GW & SW- throughout Manganese – GW & SW- throughout Iron -SW- localised Iron -SW- localised TDS- GW- Localised TDS- GW- Localised TH- GW- Localised TH- GW- Localised 6/16/2009

Comparison to other catchments Similar results Zhulube catchment (Tunhuma) Similar results Zhulube catchment (Tunhuma) Hg noted in Zhulube not analysed in this study Hg noted in Zhulube not analysed in this study Lesser sites contaminated than Moza (Chilundo) Lesser sites contaminated than Moza (Chilundo) Zn, Cu, Fe, Na+, Ca2+, Mg2+ noted in Moza not a problem in study area Zn, Cu, Fe, Na+, Ca2+, Mg2+ noted in Moza not a problem in study area As & Se noted in S.A not analysed in the two sub catchments As & Se noted in S.A not analysed in the two sub catchments 6/16/2009

Recommendations Follow up Cd problem (different lab) Follow up Cd problem (different lab) Establish source of Cd (natural vs pollution) Establish source of Cd (natural vs pollution) Establish threshold limits for the communities associated Establish threshold limits for the communities associated Hg not analysed due to costs need to be followed up as it was picked in Zhulube Hg not analysed due to costs need to be followed up as it was picked in Zhulube Encourage responsible farming so that the quality of water does not deteriorate further Encourage responsible farming so that the quality of water does not deteriorate further 6/16/2009

THANK YOU 6/16/2009