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Environmental Pollution > Week 7- Biosphere Pollution > Flashcards

Week 7- Biosphere Pollution Flashcards

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1
Q

What is the behaviour of ionic contaminants dictated by?

A

The charge which they hold

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2
Q

Why has Manganese become an emerging containment ?

A

Slow oxidation

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3
Q

Mn(II) vs Mn(III)/(IV)

A

MN II is soluble and ionises more slowly to insoluble MN (III)/(IV) oxides

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4
Q

Issues arising from high concentration of Manganese exposure?

A

Adults- a Parkinson like disorder
Children- decline in intellectual function

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5
Q

Purpose of Eh-pH diagrams

A

They are used to assess the behavior of inorganic contaminants by showing the stable conditions for different chemical species at various pH and redox levels.

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6
Q

What do the dotted lines represent in an Eh-pH diagram?

A

The dotted lines represent the redox limits within which liquid H2O can exist.

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7
Q

Eh (redox potential)

A

This represents the tendency of a substance to gain or lose electrons, essentially showing how oxidized or reduced a species is.

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8
Q

What does it mean when soils are amphoteric?

A

SOil surfaces can bve both positively and negatively charged

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9
Q

Relation between Mn reduction and acidic needle depositions

A

Acidic needle depositions may lower pH of soils and waters, promoting Mn reduction

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10
Q

Importance of biology and maganese

A

Many biological routes from soluble-insoluble manganese

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11
Q

What environmental factors promote manganese reduction in the diagram?

A

Acidic needle depositions (lowering pH) and increased degrading organic material (electron donors) with microbial activity promote Mn reduction, releasing Mn²⁺ into soil and water.

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12
Q

How does pH affect the transformation of manganese oxides?

A

Low pH (high H⁺) promotes Mn reduction by lowering redox potential, stabilizing Mn oxides but allowing reduction to Mn²⁺ with electron donors. High pH reduces H⁺, leading to negatively charged soil surfaces and Mn²⁺ release into solution, destabilizing Mn oxides.

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13
Q

What role does dissolved organic matter (DOM) play in manganese transformation?

A

DOM acts as an electron donor, reducing Mn(IV) oxides to Mn(III) or Mn²⁺ through oxidation reactions, losing electrons (e⁻) or protons (H⁺), and transforming into altered organic compounds that may bind to soil or remain in solution.

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14
Q

Geological factors controlling dissolved Mn

A

Rock weathering provides an ongoing source of Mn BUT
* Redox-related processes mean that Mn concentrations in underlying strata may not directly control those in surface
waters, sediments and soils

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15
Q

Soil catchment factors controlling dissolved Mn

A

Mn concentrations often reflect
soil type
BUT
* Factors such as redox potential
and pH control soluble Mn
inputs into surface waters
* In addition, soil organic matter
(OM) content can help stabilize
soluble Mn and mobilize
insoluble oxides

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16
Q

Vegetation catchment factors controlling dissolved Mn

A
  • May impact Mn runoff into
    surface waters through soil
    feedbacks
  • Coniferous forests tend to
    result in greater Mn
    mobilisation because they
    promote acidic soil
    conditions
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17
Q

Internal cycling - Manganese

A

Seasonal boundary (thermocline) within reservoirs can shift - depending on intensity of heating- dynamic process that is modulated by climate

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18
Q

What are the main pathways for manganese to enter water bodies?

A

Surface runoff and groundwater seepage, driven by reductive dissolution of Mn(IV) to Mn²⁺ under reducing conditions.

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19
Q

How does manganese redox cycling occur, and what influences it?

A

Mn cycles between insoluble Mn(IV) and soluble Mn²⁺ (via Mn(III)) through reductive dissolution. Influenced by anoxic/acidic vs. oxic/alkaline conditions and microbial activity.

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20
Q

What happens as water warms to manganese solubility?

A

Manganese solubility decreases in oxic surface waters due to oxidation and precipitation of Mn(IV) oxides, but increases in anoxic deep waters due to microbial reduction to Mn²⁺, depending on redox, pH, and stratification.

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21
Q

What environmental condition can catalyze Mn reduction?

A

Hypoxia caused by algal blooms can catalyze Mn reduction.

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22
Q

How can algae accumulation affect the environment?

A

Algae accumulation can amplify anaerobic conditions, thus enhancing redox processes during decompositio

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23
Q

What do decomposing algae provide that aids Mn and Fe reduction?

A

Decomposing algae provide Dissolved Organic Matter (DOM) suitable for Mn and Fe reduction.

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24
Q

What type of DOM is suitable for Mn binding and mobilization?

A

Increased aromatic DOM in the water column is suitable for Mn binding and mobilization.

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25
Nanoparticles
Structures with at least one dimension of 100 nanometers or less
26
Nanomaterials
Nanoparticles in a form that serves a particular function (engineered nanomaterials)
27
Nanoproducts
Commercial products that include or incorporate nanomaterials distributed in a matrix
28
What are the 4 types of nanomaterials?
- Inorganic based - Carbon based - Organic - Composite based
29
Difference between ionic metal contaminants compared to Nanoparticles in terms of distribution sizes?
Unlike ionic metallic contaminants the distribution of nanoparticle (NP) sizes dictates NP properties and attributes
30
What does the diameter of nanomaterials mean for human health effecs?
Diameter of nanomaterials changes its behaviour e.g. reactivity/energy meaning it can depend whether the particle is inert or not within human
31
ROS-Free radicals
Reactive Oxygen species
32
3 main things dictating properties of nanoparticles
Size, shape and coatings
33
Shell/coatings
Used to protect the core from being degraded in trasnport/prevent reactions too soon e.g. citrates / PVP/DEXTRAN
34
What does Dynamic Light Scattering (DLS) measure?
Measures the fluctuations in the intensity of scattered light caused by the Brownian motion of particles in a solution
35
Process of DLS?
Laser → Scattered light by particles detected → Intensity fluctuations analysed → Diffusion coefficient calculated → Hydrodynamic diameter (Stokes-Einstein) → Average size & size distribution.
36
What is transmission electron microscopy (TEM) process ?
Grid prep → Thin layer → Measures particle width (1 nm–µm) → < 1 Å resolution → Long analysis time → Difficult for complex samples but means we cna gather shape and size
37
What is the process of Atomic Force Microscopy? (AFM)
Sharp tip on cantilever → Measures tip-sample forces → Laser detects cantilever deflections → Topography with ~1 nm resolution in 3D.
38
Process of Size exclusion Chromatography?(SEC)
Separates by hydrodynamic volume → Larger particles elute first, smaller particles later → Porous SP (e.g., dextran, agarose) → Best for spherical/homogeneous particles.
39
(Single Particle) SP_ICP_MS
- Unlike traditional ICP-MS samples should NOT be acidified – may cause NP’s to precipitate / dissolve etc. - Continuous signal of lower intensity: dissolved metal (background, nearly always present in environmental samples / biological samples) - Pulses of higher intensity (duration of ca. 300 – 500 µs): Nanoparticles
40
Equation : distinguishing small particles from background noise
Dmin=((6 × 3𝜎𝐷𝑖𝑠𝑠𝑜𝑙𝑣𝑒𝑑 𝑚𝑒𝑡𝑎𝑙)/(𝑅×𝑓𝑎 × 𝜌 × 𝜋))
41
Strategies to reduce background noise? ICP
Adding Ion exchange resin (IEC) is a gel like matrix that can remove charged molecules and atoms from solution
42
What are natural nanoparticles?
Made by nature through biogeochemical or mechanical processes
43
What are incidental nanomaterials?
Unintentionally produced as a result of direct or indirect anthropogenic processes
44
What are engineered nanomaterials?
Conceived, designed and unintentionally produced by humans
45
Why is NanoSilver (AgNP) significant?
- It has the greatest global market share of all NP - It is an antibacterial agent - Potential prelease into surface waters from waste water treatment plants
46
Range of toxicological responses to exposed organisms that can be created?
Nanomaterial can act as a vector for more toxic particles
47
Example of Nanotitanium oxide being a problem
UV-enhanced toxicity can lead to the death of goldfish skin cells/ coral bleaching
48
Case study- Leiden University- impact of nano particles on filter feeders
Specific decrease in filter feeder abundance. The reduction Daphnia (herbivorous zooplankton) eases predator pressure on phytoplankton species resulting in a shift in community structure and potentially water quality.
49
3 main fates of nano silver (AgNP) in aquatic ecosystems
Dissolution, Aggregation, Adsorption
50
Dissolution of AgNPs
The oxidation of metalli Ag to silver ions in the presence of oxidants
51
Aggregation of AgNPs
Occurs when the nanoparticles lose their surface coatings and capping agents
52
Adsorption of AgNP
Occurs due to the appending of various natural capping agents e.g. organic matter
53
Water chemistry affects Ag NP fate - Sulphur
Ionic Silver reacts with a metal sulphide molecule. Resulting in the formation of NP-sulphide and free ionic parent metal Direct and indirect oxysulfidation occur at high and low sulphur concentrations
54
Water chemistry affects Ag NP fate - Chlorine
AgCl forms a main constituent of the corrosion layer formed on the surface of AgNPs AgCl obtained from the oxidative dissolution of AgNPs include their conversion to sulfides, and reduction to elemental silver in the presence of UV irradiation. Therefore Water turbidity also affects NP fate and stability in lake ecosystems
55
Surface coatings + Dissolved organic matter (DOM) affects fate of AgNP
Lipoic acid was the least able to prevent agglomeration in all three media PVP showed the highest protective effect of the three surface coatings studied Dissolved organic matter concentrations and type are a critical parameter and confer a specific effect
56
How do difference coatings behave at different pH and ionic strength?
Lipoic acid was the least able to prevent agglomeration in all three media PVP showed the highest protective effect of the three surface coatings studied Dissolved organic matter concentrations and type are a critical parameter and confer a specific effec
57
Catchment factors controlling Dissolved Mn- Geology
Rock weathering provides an ongoing source of Mn BUT Redox-related processes mean that Mn concentrations in underlying strata may not directly control those in surface waters, sediments and soils
58
Catchment factors controlling Dissolved Mn- Soil
* Factors such as redox potential and pH control soluble Mn inputs into surface waters * In addition, soil organic matter (OM) content can help stabilize soluble Mn and mobilise insoluble oxides
59
Catchment factors controlling Dissolved Mn- Vegetation
* May impact Mn runoff into surface waters through soil feedbacks * Coniferous forests tend to result in greater Mn mobilisation because they promote acidic soil conditions
60
What time period is the cycle of manganese within reservoirs?
Annual
61
What do low levels in reservoirs mean for Mn
DO decreases due to decreased turbulence and lower gas exchange - Algal blooms due to increased nutrients, low DO and higher temps - Changing redox condition
62
What do reservoir levels control
Sediment rewetting and concentration of nutrients
63
How can hypoxia caused by algal blooms lead to Mn reduction
* Algae accumulation- amplifies anaerobic conditions and redox processes during decomposition * Decomposing algae provided DOM for Mn and Fe reduction * Increased aromatic DOM in water column= suitable for Mn binding and mobilisation
64
Solutions to reducing hypoxia
* HOx system *Res Mix * Water lifting aerators
65
Methods of measuring metal contaminants - Spectroscopy
* Atomic absorption Spectroscopy * Colorimetry
66
Methods of measuring metal contaminants - Spectrometry
ICP-MS
67
Impacts of lead exposure
* Developmental delays * Cardiovascular issues * Neurological damage * Kidney damage
68
How can lead be restricted
Using phosphoric acid (H3PO4) to create a stable solid
69
Pathways of Pb into the environment
- Lead acid batteries - Mining - Fossil fuels - Forest fire fumes
70
What does size of NP dictate?
Properties and attributes e.g. melting point of tin decreases with diameter
71
What does shape of NP dictate?
How stable nanoparticles are in solution
72
What do coatings of NP dictate?
The environmental fate of NP
73
What does DLS measure in NP?
Average size and distribution
74
What does TEM measure in NP?
Particle width
75
What does AFM measure in NP?
Topographical features to 1nm in all three axes
76
What does SEC measure in NP?
Hydrodynamic volume (size)- only effective for spherical, uniform particles
77
What can be used to reduce background noise when measuring nanoparticles?
IEC- ion exchange resin= a gel like matric that can remove charged molecules and atoms from solution= better detection of smaller NPs
78
Types of nanomaterials
- Natural - Incidental - Engineered
79
Fate of AgNP in aquatic ecosystems
- Dissolution- oxidation of AgNP to silver ions - Aggregation- nanoparticles lose surface coatings/capping agents - Adsorption- occurs due to appending of natural capping agents e.g. OM
80
Evidence of Ag in ecosystems
Bioaccumulation found in perch an pike liver and the density of fish was also reduced

Environmental Pollution (9 decks)

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