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Manganese - A Water Pollution Indicator Or Natural Groundwater Chemistry

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This is a presentation that I gave to my UF Soil & Water Science Department, Geochemistry of Heavy Metals postgraduate class.

This is a presentation that I gave to my UF Soil & Water Science Department, Geochemistry of Heavy Metals postgraduate class.


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  • 1. CWR 6252 BIOGEOCHEMISTRY OF TRACE METALS MANGANESE – A GROUNDWATER POLLUTION INDICATOR OR NATURAL GROUNDWATER CHEMISTRY? 19 th April 2010 Padraic Mulroy
  • 2.
    • INTRODUCTION
    • ANTHROPOGENIC INPUT
    • AIR
    • SOIL & SEDIMENT
    • WATER
    • BIOCONCENTRATION IN BIOTA
    • HUMAN TOXICITY
    • INFLUENCE OF REDOX & pH
    • ELEVATED LEVELS IN POLLUTED GROUNDWATER
    • NATURAL ELEVATED LEVELS IN BEDROCK
    • CONCLUSIONS
    PRESENTATION OVERVIEW 1 Introduction 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
  • 3. INTRODUCTION 1 Introduction 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
    • Group 7
    • Reddish grey/silver brittle element
    • Oxidation states of +1, +2, +3, +4, +6 and +7
    • Omnipresent – 0.1% of Earth’s crust
    • 12 th most abundant element (Iron more abundant)
  • 4. INTRODUCTION 1 Introduction 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
  • 5. INTRODUCTION 1 Introduction 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
    • Principal ores – Pyrolusite (MnO 2 ) and Rhodocrosite (MnCO 3 )
    • Large deposits in Cuyuna Range (Minnesota), Ukraine, Georgia, China
    • Common constituent of sedimentary rocks such as shales (southeast of Ireland)
    ACICULAR/RADIAL DENDRITIC
  • 6. INTRODUCTION 1 Introduction 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
    • Manganese nodules – rock concretions on sea bottom (concentric layers of Mn & Fe hydroxides)
    • Contain Mn (27-30%),
    • Fe (6%), Ni (1.25-1.5%),
    • copper (1-1.4%)
    • & cobalt (0.2-0.25%)
    • Possible future
    • mineral resource?
    OCEAN FLOOR CROSS-SECTION POSSIBLE HARVESTING?
  • 7. ANTHROPOGENIC INPUT
    • Municipal WWTP discharges to aquatic systems
    • Application of biosolids to land & marine dumping
    • Mining & mineral processing
    • Air emissions:
      • alloy, steel & iron production, combustion of fossil fuels
      • Combustion of unleaded petrol with anti-knocking agent Methylcyclopentadienyl manganese tricarbyl (MMT) –
      • Canadian problem?
    1 Introduction 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
  • 8. AIR
      • Concentrations in air
        • Remote: 0.5-14ng/m 3
        • Rural: 40ng/m 3
        • Urban: 65-166ng/m 3
      • Highest in source dominated areas – up to 8,000ng/m 3
      • Annual averages near foundries 200-300ng/m 3
    1 Overview 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
  • 9. SOIL & SEDIMENT
    • Concentrations in soil
      • Range <1-4,000mg/kg
      • Average 300-600mg/kg
    • Sources:
      • Crustal
      • Atmospheric deposition
      • Run-off from plant and other surfaces
      • Leaching from plant tissue
      • Leaves, dead plant
      • Animal material detritus & excrement
    • Sources of Mn 2+
      • Anaerobic environment
      • Natural weathering of Mn 2+ minerals
      • Naturally acidic environments
    • Sedimentation factors
      • Oxygen concentration in overlying water column
      • Penetration of O 2 into sediment
      • Benthic organic carbon supply
    1 Overview 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
  • 10. WATER
    • Concentrations in natural waters
      • Range <1-10,000 μ g/litre
      • Average <200 μ g/litre
    • Concentrations in unpolluted river sediments
      • Range 410-6,700 μ g/litre
    • Urban lake in vicinity of old mine tailings dump
      • Sediment 13,400 m g/kg
    • Intertidal mudflats
      • Range 100-1,000 m g/kg
      • Unpolluted Dundalk mudflat 421 m g/kg
    • Baltic Sea – Ferromanganese Nodule Area
      • Range 3,550-8,960 m g/kg
    1 Overview 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
  • 11. BIOCONCENTRATION
    • Bioconcentration at lower trophic levels
      • BCF 2,000-20,000 for marine/freshwater plants
      • BCF 800-830 for intertidal mussels
      • BCF 35-930 for fish
    • Uptake increases with increasing temperature but decreases with increasing pH
    • Dissolved O 2 – No effect
    • Concentration of Mn in fish flesh
      • Range: <0.2-19mg/kg
      • Higher (i.e. >100mg/kg in polluted waters)
    • Essential nutrient for terrestrial plants
      • Requirements: 10-50mg/kg tissue
      • Members of Ericaceae family (includes blueberries) are recognized hyper-accumulators
    1 Overview 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
  • 12. HUMAN TOXICITY
    • Adverse effects in humans via inhalation – neurotoxin causing ataxia, co-ordination impairment, anxiety, dementia, ‘mask-like’ face, involuntary movements, similar to Parkinson’s disease
    • Manganism or ‘Welder’s Disease’ – inhalation of toxic welding rod fumes – not age dependent
    • Mangasim found in farmers exposed to Manganese containing pesticides e.g. maneb (fungicide), rotenone (a insecticide)
    • Level of manganese found in groundwater supplies in Ireland/US far below average daily intake of manganese from food
    • Neurological effects were observed in the elderly within a group of families exposed to elevated manganese. No effect on youngest.
    1 Overview 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
  • 13. INFLUENCE OF pH & REDOX 1 Overview 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
    • MnO 2 (Pyrolusite) – stable compound at high redox regardless of pH
    • MnCO 3 (Rhodocrosite) – stable over a wide redox and pH range if carbonate is high
    • MnO 2 -CO 2 -H 2 O-S 2 -O 2
  • 14. INFLUENCE OF pH & REDOX 1 Overview 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
    • H æmatite, iron(III) oxide (Fe 2 O 3 ) dominance shows Fe oxidises more readily in natural environment
    • H æmatite stable in presence of Mn 2+ over wide pH range
    • Precipitation of Mn 2+ will happened with increasing pH if carbonate or silica is present
    • If environmental becomes more oxidising, Mn will precipitate as one of oxides MnO 2 most stable
    • MnO 2 -CO 2 -H 2 O-S 2 -O 2
  • 15. ELEVATED LEVELS IN POLLUTED GROUNDWATER 1 Overview 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
    • CASE STUDY A
    • Groundwater in vulnerable upland area polluted with septate from neighbour’s malfunctioning on-site WWTP
    • Introduction of carbon source will cause:
      • Aerobic microbial consortia to use up all O 2
      • Biofouling of borehole
      • Drop in Dissolved O 2 - Redox Potential drop
      • Anaerobic & facultative anaerobic consortia will take over & produce initially acid & fatty acid breakdown products
      • Increase in acidity -> pH drops
      • Reduction of Mn 4+ (solid MnO 2 ) -> Mn 2+ (soluble)
      • Solubilization of solid MnCO 3 -> Mn 2+
      • Reduction of ferric Fe 3+ (solid haematite) ->
      • ferrous Fe 2+ (soluble)
      • Production of ammonia
      • Moving down the Redox Ladder
  • 16. ELEVATED LEVELS IN POLLUTED GROUNDWATER 1 Overview 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
    • CASE STUDY A – NE IRELAND
  • 17. ELEVATED LEVELS IN POLLUTED GROUNDWATER 1 Overview 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
    • CASE STUDY A
    • OLD POLLUTED
    • BOREHOLE
    • NEW UNPOLLUTED
    • BOREHOLE
  • 18. NATURAL ELEVATED LEVELS IN GROUNDWATER 1 Overview 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
    • CASE STUDY B – COUNTY WEXFORD
    • 83m deep water abstraction borehole drilled to
    • supply 19 residences
    • Grey shale bedrock becoming greyer with depth
    • Soft rock encountered at 81-83m bgl followed by large water strike
    • Pump tested over 72 hours - sustained yield of 30.2m 3 /day
    • 3 sets of samples taken for laboratory analysis – 24, 48 & 72 hours
    • Elevated Mn levels - 1,140 to 670μg/litre –
    • Drinking Water Limit - 50μg/litre ( 10 times!)
    • Normal Fe levels 60 to 250μg/litre
    • No ammonia, nitrates or bacteria
    • Excellent clarity, no odour or taste
    • Flow cell Redox 129mV
  • 19. NATURAL ELEVATED LEVELS IN GROUNDWATER 1 Overview 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
    • CASE STUDY B
    • Ballylane Formation - laminated green, green grey and grey slaty mudstones and green or pale grey siltstones, with occasional greywacke sandstones and andesitic volcanics’
    • Maulin Formation – dark phyllites, quartz rich siltstones which contain very small manganese-rich garnets
  • 20. NATURAL ELEVATED LEVELS IN GROUNDWATER 1 Overview 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
    • CASE STUDY B
    Mn 2+ - Rich Groundwater?
  • 21. NATURAL ELEVATED LEVELS IN GROUNDWATER 1 Overview 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
    • CASE STUDY B
    • CASE STUDY B – COUNTY WEXFORD
    • Where is the Mn coming from?
      • Possibly went through Ballylane Formation into Maulin Formation at 81m bgl which is proven to have Mn-rich garnets or coticules
      • MnO 2 or MnCO 3 deposits within Ballylane Formation
  • 22. NATURAL ELEVATED LEVELS IN GROUNDWATER 1 Overview 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
    • CASE STUDY B
    • CASE STUDY B – COUNTY WEXFORD
    • What is the solution?
      • ‘ Manganese Greensand’ is glauconite greensand (zeolite) impregnated with KMnO 4
            • Capable of reducing iron, manganese and hydrogen sulfide from water through oxidation and filtration.
            • Soluble iron and manganese are oxidized and precipitated by contact with higher oxides of manganese on the greensand granules.
  • 23. CONCLUSIONS 1 Overview 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
    • SEDIMENTARY ROCK FORMATION
    • Mn deposits within shale result from 3 main processed:
      • Concentration within seawater
      • Precipitation from seawater
      • Enrichment in the sediments
    • Anoxic conditions are a basic factor for Mn concentration in seawater – weak oxic & alkaline conditions favourable for Mn carbonate precipitation with microbial activities playing a part
  • 24. CONCLUSIONS 1 Overview 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions
    • GROUNDWATER QUALITY
    • Consensus in Ireland is that Drinking Water Standard for Mn (50μg/litre) is not health driven but down to aesthetic and organoleptic (i.e. taste)
    • EPA are aware of link with neurologic effects on elderly population – lack of research
    • Rural housing with on-site borehole in Mn-rich geological formation areas – elderly residents are at risk
    • Need for technical guidance and/or assistance with on-site water treatment systems
  • 25. THANK YOU! 1 Overview 2 Anthropogenic Input 3 Air 4 Soil & sediment 5 Water 6 Bioconcentration 7 Human Toxicity 8 Influence of Redox & pH 9 Elevated levels in polluted groundwater 10 Natural elevated levels in bedrock 11 Conclusions Thanksgiving, Gainesville, 1995 (20 kilos lighter)