Environmental Pollution

Run of River hydropower

water is diverted from river, and runs through turbine

pump and store

usually requires building a dam, provides electricity at peak energy demand, and uses excess at night to pump water up

large scale storage

i.e. 3 Gorges dam, but can flood greenery, which causes decomposition of organic material and CO2 can be released

Installed Capacity (Wind Power)

amount of energy we could produce if turbines are working at maximum capacity all of the time

Base load

energy provided doesn’t change over time, for example nuclear power

Variable load

can increase output from energy sources when demand is high

peak demand

when energy demand is highest, i.e. in the morning and around dinner time

acrotelm

upper region of peat, the zone of living plants, can filter water very well and is partially aerated

catotelm

the lower region of peat, no living plants, accumulates plant material (humic material) and stores most of the carbon

Why is peat important in wind energy

the places with high wind are also places where there is a lot of peat (high elevation) if turbines are built, it can increase the amount of CO2 released from peat (b/c if you dry out the peat, increases oxygen into the lower layer and causes aerobic decompositon)

Peatland rewetting

peatland rewetting can cause the humic material to get broken down and escape into drinking water, which then can cause DBPs further down the line and accumulate other contaminants

Deep Geothermal

heat from depths >500m, partly radioactive heat and partly primordial heat

Solution for peat wind farm issue

Floating roads, a road with 1 or 2 layers of geogrids that distribute load evenly and line sides with peat to avoid water run-off

Binary Cycle Geothermal

Geothermal is <150-180 C, so we use a highly efficient heat exhanger to heat water and make steam to turn a turbine. A closed loop cycle with direct return of fluids to depth, so no liquid or gas emissions

Hydrothermal systems

Wet steam vs. dry steam (wet steam is water under high pressure but at surface turns into steam), used to turn a turbine. Can also release gases like CO2, CH4, H2S, NH3

Physical Carbon Capture

Absorption (selexol) and adsorption (zeolites, etc.)

Chemical Carbon Capture

Absorption (using amines) and bonding

Lithium ion batteries

sealed, 80% capacity, lasts 20+ years, 3000-5000 cycles, more expensive upfront, cheaper per kWh

Where is lithium found

lithium can be found in brines and minerals, Chile has most of the world’s Lithium

Environmental Impact of processing Lithium

Land Use - 3124m² per tonne Li, Water use - 469 m³ per tonne Li, CO2 emissions - 5000kg/tonne Li

Tailings

Batteries use secondary metals and mining them and processing creates tailings, exponential growth of tailings,

we leave tailings in sludge ponds or piles and just leave them there - spray water on them which is a huge water sink

Acid mine drainage

cascade effect of acidity, dissolves heavy metals as well

Contamination Factor

CF = Cmetal/Cbackground

measured concentration / pre industrial/natural concentration

low contamination is CF < 1

moderate contamination is 1 < CF < 3

considerable contamination is 3 < CF < 6

high is CF > 6

Li Recovery

pyrometallurgy - combust Li in a furnace at 1000C to recover

hydrometallurgy - recovers desired metals by leaching in acidic or basic solution

biometallurgy - bacteria that can precipitate out metal

Landfill Fires

emerging environmental concern, can release HF (hydrofluoric acid), a major hazard and can cause serious toxic effects

solution to Li-ion battery recycling

Closed loop system - for different types of materials there could be different types of recycling

Vanadium

Important for many high tech and economically significant tech. Vanadium reflow plants are becoming popular

low energy density, more expensive, lasts longer, but requires high purity (rare)

supply risk is high

vanadium is potentially toxic to aquatic organisms

Nuclear power

provides a base load of energy

large amounts of energy released from comparatively small amount of fuel

Uranium

3 main isotopes - U-234, U-235, U-238

U-235 is fissile, used as fuel for nuclear power plants but only makes 0.7% of naturally occuring uranium

Uranium mining

main ores are uraninite and carnotite

open cast mining, using crushing and flotation to separate ores from impurities

Uranium refining

+IV oxidation state - insoluble

+VI oxidation state - soluble

to extract uranium, it is first oxidized, then extracted by adding sulfuric acid

organic solvent is used to separate uranium from other species

after recovery of uranium, it is precipitated

Environmental Impact of Mining and Refining Uranium

fine to coarse particles in slurry

Radium - highly soluble, leaches out

Radon - gaseous, can diffuse out

Enrichment

For energy, you just need 3% enriched uranium (for weapons you need 95%)

Nuclear spent fuel - what to do w it

generates a lot of heat, stored underwater for 6-12 months

cut up into small pieces and dissolved

reprocessed

separation of U and Pu from fission products, extraction w U and Pu going to organic layer, fission products in aqueous layer (TOGDA)

Intermediate level liquid waste (ILLW), High level liquid waste (HLLW), High level solid waste (HLSW)

ILLW - <4×10^4 GBq/m³

HLLW - ~10^7 GBq/m³

HLSW - cladding from fuel rods, etc.

LLW makes up a lot of nuclear waste, very low activity and can be disposed of by dumping into ocean

Deep disposal of nuclear waste

multi-barrier approach - physical containment, geological isolation, chemical conditioning, stable rocks (300-1000m underground)

absence of large fractures in solid repository matrix

impermeability to water

good heat conductivity

Half-Life equation

A = lambda*N(t)

activity = decay constant (1/s) * atom number

Waste Isolation Pilot Plant

military waste was places in steel canisters, the salt bed was not water free, corroded the waste canisters and there was a major explosion

Future of Nuclear

Thorium-232 is not fissile, but it is fertile (can absorb neutrons and convert into fissile)

3x more abundant than uranium

doesn’t require water as a primary coolant

5x less mining waste than uranium

but also complicated and expensive

Load Factor

(actual generation/installed capacity) *100

Pesticides

bactericide, fungicide, herbicide, insecticides

traditional pesticide problems

usually very toxic to humans and mammals at dosages required to make them effective

non-biodegradable

Desirable characteristics of a pesticide

1. small amount needed

2. low toxicity to non-target species

3. lifetime just long enough to kill target pests

4. degrades to benign products

5. does not accumulate in living organisms

6. does not runoff with water from application site

7. pests are slow to develop resistance

DDT

agricultural insecticide that opens sodium ion channels in neurons, causing death in insect

silent spring - rachel carson, documented impact of ddt on wildlife

bioconcentration, bioaccumulation & biomagnification

bioconcentration - higher concentration of a chemical in organism than the environment in which it’s exposed to

bioaccumulation - uptake of a chemical by an organism following consumption of a food source

biomagnification - sequence of processes by which higher concentrations of a chemical are reached in organisms higher up in the food chain

How do we detect DDD, DDE, DDT

liquid-liquid extraction using solvent like DCM

gas chromatography

Organophosphates

Insecticides - Parathion and malathion are examples of compounds

parathion - highly toxic to non-target organisms

• cholinesterase inhibitor

• absorbed through skin and mucous, rapidly metabolized

malathion - low toxicity

Pyrethroids

• naturally occurring organic compounds with insecticidal properties

• attacks nervous system of all insects - even to beneficial ones

• toxic to base of food webs

we detect w conventional methods (GC-MS, FTIR, UV-Vis) or biosensors

Emerging Organic Pollutants

• pharmaceutical and personal care products

• perfluorinated compounds

  • endocrine distrupting potential

  • bioaccumulate/persistent properties

  • carcinogenic

Disruption of the endocrine system

some chemical mimic natural hormones, others block the effects of a hormone from certain receptors, others stimulate or inhibit the endocrine system and cause overproduction or underproduction of hormones

Ibuprofen

Ibuprofen has R and S form, human body converts R to S form

influent waste treatment waters contain mainly active form of drug + metabolites

high mobility in aquatic environment, concern about fate and effects

Triclosan

• non-toxic

• lipophilic, accumulates in fatty tissues

• may interfere w thyroid hormone metabolism

• toxic to algae

PFCs: PFOS & PFAS

PFOS - fire resistant, fabric protection, etc.

persistent, bioaccumulative, and toxic to mammals

causes cancer, endocrine disruption, neonatal mortality, reduced birth size

PFAS is found in drinking water, etc.

can be removed using activated carbon, ion exchange, or membrane filtration

Solubility

• mass of solute that can dissolve in water

high solubility - >100 mg/L

moderate solubility - 10-100 mg/L

low solubility - <10 mg/L

Octanol-Water Partitioning

Kow = concentration in octanol / concentration in water

dimensionless ratio expressing distribution of organic pollutant between equal volumes of octanol and water

LogKow < 3 —> organic chemical remains in water

LogKow > 3 —> organic chemical partitions into soil/sediment

log P is equivalent to logKow, relates to the non-ionised form of the substance at pH where non-ionised form dominates

Bioconcentration Factor (BCF)

BCF = concentration in living organism / concentration in water

BCF < 100 - low tendency to bioconcentrate

100 < BCF < low 1000s - medium tendency

BCF > 5000 - high tendency to bioconcentrate

Why is accumulation in living organisms important?

• toxicity

• chemical burdens reduce fitness and resilience

• food chain impacts

• endocrine disruption

Vapour Pressure

pressure when liquid is at equilibrium with it’s vapour

<0.01 kPa = nonvolatile

> 0.01 kPa = volatile

Henry’s Law Constant

Kh = partial pressure in atmosphere / concentration in water

Kh = p(organic chemical)/ organic chemical

Kh > 100 Pam³ /mol —> volatile

Kh < 100 Pa m³/mol —> nonvolatile

Degradation Times

pathways: photolysis (photodegradation), hydrolysis, biodegradation

Environmental half life: t ½

Degradation Time 50%: DT50

Persistence - Resistance to Breakdown

Water DT50 > 2 months

Soil DT50 > 6 months

sediment DT50 > 6 months

Ionisation - Dissociation pKa & pH

• organic chemicals may dissociate, can influence fate, behaviour, and toxicity

• ionisation is driven by pH

• pKa is pH at which half of chemical is ionised

pKa = -logKa

for neutral chemicals that ionise by releasing H+

pH < pKa = majority of chemical is not ionised (HA)

pH > pKa = majority of chemical is ionised (A-)

Biogeochemical cycles

• Nature has slow occurring ones for trace elements and heavy metals

• these cycles are controlled by environmental conditions

• trace elements and heavy metals cannot be degraded like some organic pollutants

Inorganic contaminants

• metals and their salts

• inorganic fertilizers

• sulfides

• ammonia and oxides of nitrogen

• acids and bases

Metals - pollutants

naturally occuring and anthropogenic sources

• speciation of metals dictates behaviour

  • oxidation state, complexation, pH, redox conditions —> determine mobility, toxicity, and bioavailability

Discoloured tap water

Mn and Fe have soluble and insoluble forms in aquatic systems

• Fe(II) is soluble, oxidizes rapidly to form insoluble Fe(III)

• Mn(II) is soluble, oxidised much more slowly to insoluble Mn(III)/(IV) oxides

• soluble Mn is difficult to remove during water treatment

• generally, reduced species are more likely to be soluble

Eh-pH Diagrams

• dotted lines represent the redox limits that liquid H2O can exist at

• each field shows pH and redox values a certain species is stable at

• species oxidation state controls mobility

Why is Mn in drinking water a problem?

• >50 microgram/L causes aesthetic concerns

• at higher concentrations, potential for adverse effects upon human health

  • manganism, parkinson like disorder

  • decline in intellect in children

  • WHO limit is 400 microgram/L

What controls dissolved Mn?

Geology

• rock weathering is ongoing source

  • redox related processes mean Mn concentrations may not directly control those in surface water/sediment/soil

Soils

• Mn concentrations reflect soil type

  • redox potential and pH control soluble Mn inputs into surface waters

  • in addition, soil OM content can help stabilize soluble Mn and mobilize insoluble oxides

Vegetation

• may impact Mn runoff into surface waters through soil feedback

  • coniferous forests tend to result in greater Mn mobilization, acidic soil environments

Mn Pathway into water bodies

Redox cycling between Mn(II) (soluble) and Mn(IV)O2 and Mn(III) (both insoluble) —> due to acidic v. alkaline conditions and microbial activity

goes into water from surface runoff and groundwater seepage

Manganese Annual Cycle in reservoirs

Lakes/Reservoirs have seasonal overturn

• heating throughout spring and summer creates thermocline

• causes anoxic conditions in bottom water during summer

• as water cools, the thermocline breaks down and water recirculates

• dissolved Mn spikes from Jun-Oct

Internal Loading for Mn

Mn stored in bottom sediments is released during thermal stratification and anoxia

Algal production relation to Mn + As

Can drive Mn cycling in lakes, surface photosynthesis promotes Mn oxidation, sinking organic matter fuels Mn reduction

As adsorbs to Fe and Mn, algal deposition enhances Fe/Mn reduction, increasing As mobilisation

Speciation determines mobility and toxicity

Redox stratification - Mn

Creates a Mn shuttle: Mn2+ oxidises in oxic waters and is reduced back to Mn 2+ in anoxic layers

Carbon cycling - Mn

Mn cycling is coupled to carbon cycling, changes in productivity directly regulate Mn redox dynamics

In-Situ solutions

HOx system - oxygenates bottom of lake, but Mn continues to leak out of bottom sediments

Resmix - causes clouds of resuspended sediment

Water lifting aerators - reduce elevated levels of Mn and Fe, prevented hypoxia and caused release of reduced Mn and Fe species

Spectroscopy

1. Sample preparatiom

2. Atomization

3. Light absorption

4. Detection and quantification

5. Calibration and Analysis

Colorimetry

Sample preparation, reagent addition, measurement, and calibration curve

beer lambert law: A = epsilon*c*l

ICP-MS

Ionises sample in plasma, measures mass to charge ratio

Can detect multiple elements, precise

Pb in drinking water

Current and legacy sources can be mobilised into freshwaters

Main method of controlling Pb is phosphoric scid, which reacts w highly soluble PbCO3 to make a stable solid btw. pH 6-10

Phosphate creates protective layer inside water distribution pipes

Mn future risk

May pose a risk to potable water due to in-pipe cycling

Speciation controls mobility and toxicity

Chemical form determines solubility, sorption, redox behaviour, and biological uptake

Redox conditions govern metal release

Oxic conditions stabilize Fe/Mn oxides, anoxia drives reductive dissolution and metal mobilisatiom

Organic matter links biogeochemistry to contamination

Eutrophication increases oxygen demand, which shifts redox amd releases sorbed metals like As

Solid phases are dynamic, not permanent links

Metals adsorbed to sediments or incorporated into corrosion scale can be released when chemistry changes

Water chemistry drives infrastructure corrosiom

Chloride, alkalinity, oxidants, and corrosion inhibitors determine metal release from pioes

Small chemical shifts can have large public health impacts

Changes in source water or trestment can destabilise equilibria and increase dissolved metal exposure

Nanoparticles

Structures w at least one dimension of 100 nm or less

Nanomaterials

Nanoparticles in a form that serves a particular function

Nanoproducts

Commercial products that include or incorporate nanomaterials distributed in a matrix

Nanomaterials are categorized into 4 types

1. inorganic based

2. carbon based

3. organic

4. composite based

Nanomaterial size dependent chemical characteristics

as we increase diameter, we have lower surface bonding area/reactivity

melting point increases, energy needed increases

As adsorption on iron oxide

The smaller diameter means As is inside lattice, larger diameter particles localize As on surface

Nanoparticles - Physicochemical properties - shape

• sphere

• rod

• sheet

Nanoparticles - coatings

various coatings are used with different properties, they are important for dictating environmental fate

• citrate, pvp, DEXTRAN, casein

Nanoparticles - how do we measure?

• number of particles can vary greatly but yield same overall mass based concentration

DLS (Dynamic Light Scattering)

• laser beam is sent to sample, diffusion coefficient of particles is determined

• related to the hydrodynamic diameter of particles thru stokes-einstein eq.

• provides average particle size and size distribution

TEM (Transmission electron microscopy)

• samples are fixed using grid preparation techniques

• measures width of particles

AFM (Atomic Force Microscopy)

• sharp tip that interacts with sample surface

• measures topographical features to about 1nm in all 3 axes

SEC (Size Exclusion Chromatography)

• separates particles based on hydrodynamic volume

• more effective for spherical and homogenous size - less effective for wide size range

SP-ICPMS

• should not be acidified, continuous signal of lower intensity

• pulses of higher intensity are nanoparticles

Nanoparticles - main problem is distinguishing smallest particles from background noise

Dmin = (6×3sigma)/(R* fa* rho * pi)

sigma = sd of background

R = instrument sensitivity

fa = elemental mass fraction

rho = particle density

strategies to reduce background

• ion exchange resin can remove charged molecules from solution

Techniques for detecting and quantifying nanoparticles

Natural, incidental, and engineered nanoparticles

natural: made by nature through biogeochemical or mechanical processes

incidental: unintentionally produced by anthropogenic processes

engineered: conceived, designed and intentionally produced by humans