CWR 6252 BIOGEOCHEMISTRY OF TRACE METALS

MANGANESE –

A GROUNDWATER POLLUTION INDICATOR

OR

NATURAL GROUNDWATER CHEMISTRY?

19th April 2010

Padraic Mulroy

• 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

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• 12th most abundant element (Iron more

abundant)

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

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 (MnO2) and Rhodocrosite (MnCO3)

• Large deposits in Cuyuna Range (Minnesota), Ukraine, Georgia, China

• Common constituent of sedimentary rocks such as shales (southeast of Ireland)

ACICULAR/RADIAL

DENDRITIC

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?

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

AIR

Concentrations in air Remote: 0.5-14ng/m3

Rural: 40ng/m3

Urban: 65-166ng/m3

Highest in source dominated areas – up to 8,000ng/m3

Annual averages near foundries 200-300ng/m3

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

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 Mn2+ Anaerobic environment Natural weathering of Mn2+ minerals Naturally acidic environments

Sedimentation factors Oxygen concentration in overlying water column Penetration of O2 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

WATER

Concentrations in natural waters Range <1-10,000μg/litre Average <200μg/litre

Concentrations in unpolluted river sediments Range 410-6,700μg/litre

Urban lake in vicinity of old mine tailings dump Sediment 13,400mg/kg

Intertidal mudflats Range 100-1,000mg/kg Unpolluted Dundalk mudflat 421mg/kg

Baltic Sea – Ferromanganese Nodule Area Range 3,550-8,960mg/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

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 O2 – 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

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

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

MnO2 (Pyrolusite) – stable compound at high redox regardless of pH

• MnCO3 (Rhodocrosite) – stable over a wide redox and pH range if carbonate is high

MnO2-CO2-H2O-S2-O2

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

Hæmatite, iron(III) oxide (Fe2O3) dominance shows Fe oxidises more readily in natural environment

Hæmatite stable in presence of Mn2+ over wide pH range Precipitation of Mn2+ will happened with increasing pH if

carbonate or silica is present If environmental becomes more oxidising, Mn will

precipitate as one of oxides MnO2 most stable

MnO2-CO2-H2O-S2-O2

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 O2 Biofouling of borehole Drop in Dissolved O2- Redox Potential drop Anaerobic & facultative anaerobic consortia will take

over & produce initially acid & fatty acid breakdown products

Increase in acidity → pH drops Reduction of Mn4+ (solid MnO2)→ Mn2+ (soluble) Solubilization of solid MnCO3 → Mn2+

Reduction of ferric Fe3+ (solid haematite) → ferrous Fe2+

(soluble) Production of ammonia Moving down the Redox Ladder

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

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 AOLD POLLUTED

BOREHOLE

NEW UNPOLLUTEDBOREHOLE

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 30.2m3/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

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

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

Mn2+- RichGroundwater?

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 BCASE 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

MnO2 or MnCO3 deposits within Ballylane Formation

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 BCASE STUDY B – COUNTY WEXFORD

What is the solution?

‘Manganese Greensand’ is glauconite greensand (zeolite) impregnated with KMnO4

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.

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

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

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)