Ozone depletion

Ozone molecule consists of three bonded atoms of oxygen, which is unstable and highly reactive. In the lower atmosphere, ozone is a serious pollutant,  in the stratosphere, ozone, however, is an essential shield against ultraviolet radiation, where Ozone screens out 99% of all UV solar radiation.

Ozone depletion and CFCs

In 1974, a controversial hypothesis was proposed, suggesting that chlorofluorocarbons (CFCs) deplete stratospheric ozone. This hypothesis was based on the observations that CFCs are extremely stable in the lower atmosphere, they readily migrate to the stratosphere,  where they can be broken down by intense UV radiation, and the freed chlorine free radical can then catalyze the destruction of stratospheric ozone (e.g., CFCl₂):

                             CFCl₃ + light         ------>       Cl●    +    CFCl₂           (1)

                               Cl●     +    O₃        ------>     ClO    +       O₂               (2)

                              ClO     +   O₃       ------>       Cl●    +        2O₂             (3)

Ozone depletion thus results in significantly increased levels of biologically damaging and effects on human health, including sunburn, skin cancer, and cataracts,  as increased UV solar radiation reaches the earth’s surface.

Emission and uses of ozone-depleting chemicals
CFCs and other ozone destroyers have been widely used as aerosol propellants, refrigerants, blowing agents, cleaning solvents, and fire extinguishing agents. CFCs are thought to be responsible for most ozone depletion. Though restricted for use as aerosol propellants, CFCs are still widely used as refrigerants, and this use shows an upward trend.

The Antarctic ozone hole
Much of the world’s stratospheric ozone is produced near the equator, However, air  circulation patterns produce the greatest concentration of ozone in the polar regions. The term ozone hole refers to springtime thinning of the ozone layer above Antarctica; such thinning has been observed since the 1970s.

An Arctic ozone hole?
The ozone-deficient air masses that form over the North Pole are more mobile than those over Antarctica, thus threatening some densely populated regions of northern continents.

Tropical and midl-atitude ozone depletion
Conditions conducive to ozone depletion may occur in the tropics and mid-latitudes. Volcanic eruptions in tropical latitudes may contribute sulphur-based aerosols which trigger the necessary reactions.

Environmental effects
The potential environmental effects of ozone depletion include damage to aquatic and terrestrial food chains and a variety of  human health effects. Increased UVB exposure resulting from ozone destruction can educe primary productivity in marine food chains, thus affecting all  trophic levels and perhaps disrupting the global carbon cycle. Agricultural harvests could be negatively affected by widespread ozone depletion. Increased UV radiation due to ozone depletion is expected to increase human skin cancers and cataracts and to suppress human immune system functions.         

Ozone depletion prevent - collection and Reuse of CFCs
CFCs in refrigerators, automobiles, and other cooling systems can be collected and reused rather than discarded.

Substitutes for CFCs
The two major substitutes for CFCs, HFCs and HCFCs, are less ozone-destructive
than CFCs, but are costly and may have other environmental effects. Other CFC substitutes, such as helium and propane, show great promise but face technological and/or economic difficulties in development .

Short-term adaptation to ozone depletion
Given the realities of present and future ozone depletion, the most sensible short- term approach will center on human adaptation to increased UV levels and increased commitment to researching the ecological implications of ozone depletion.

My persona favourite tips to prevent ozone depletion:
1. Minimising person vehicle driving
2. Understanding it illegal to recharge refrigerators, freezers and home/vehicle air
    conditioners with CFCs
3. Not  purchasing or using portable fire extinguishers that contain halons
4. Using environmental-friendly household products
5. Minimising using pesticides.

Indoor air pollution

Indoor air quality  is an issue that refers to the air quality within and around buildings and structures. Indoor air pollution can be natural or anthropogenic (manmade) and many air pollutants are found much greater concentrations indoors than outdoors, which may affect the health and comfort of building occupants.

The reasons that air pollutants may be concentrated indoor is because many of the pollutants are generated by indoor sources, such as building materials and energy conservation measures often decrease the ventilation of buildings.

 Sources of indoor air pollution include but are not limited:
1. Environmental tobacco smoke;  
2. Toxic gases - SO₂, NO₂, CO, CO₂, and ozone
3. Volatile organics - formaldehyde, organic volatile compounds from cooking, paints, clean
     sprays, carpet, furniture and clothing
4. Radon gas seeping up from natural soil and rocks below buildings;
5. Pesticides used to control ants, flies, fleas and moths
6. Asbestos used as an insulating and fireproof materials
7. Particulates, inorganic (As, Cd, Pb, Hg) and soot;
8. Microbial contaminants -  molds (fungal growth), bacteria and biological aerosols.

Indoor air pollution control
1. Indoor air pollution can be controlled in most cases by a combination of filtration
     ventilation, source removal, source modification and air cleaning
2. Properly designed, installed, and operated heating and air conditioning systems can
    provide thermal comfort, optimal ventilation, and clean air for a building’s inhabitants;
3. An educated public can best make wise consumer decisions necessary to reduce indoor 
    air pollution problems.

My personal favourite tips to minimise indoor pollutants at home:

1. To use a door mat and getting it cleaned when it's dirty

2. To mope and vacuuming home floors regularly
3. To keep dirty shoes and smelling socks outdoor
4. To make your home a no-smoking place
5. Open your home windrow regularly to let fresh air indoor;
6. To use an exhaust fan when cooking
To introduce some beautiful flower sand natural plants (e.g., ferns, spider plants) indoor.

Air pollution control

Air pollution effect on human health
1. Air pollution may be responsible for a significant portion of human deaths worldwide,
    especially in densely congested and heavily polluted urban areas;
2. Many pollutants have synergistic effects on human health and may not only be directly
    toxic but can increase susceptibility to other disorders;

Air pollution effect on environment
1. Air pollution can degrade aesthetics, vegetation, animals, soils, water quality and
   structures
2. Soils, water, and cultural artifacts and structures are degraded by air pollution and its
    effects, acid rain for example
3. Soil with less CaCO₃ is much sensitive to acid rain
4. Seteriorating forest ecosystem due to tree death and soil nutrient loss caused by acid
    rain
5. Deteriorating lake ecosystem: decline in fish species and population caused by acid rain;
6. Damaging building materials, e.g, steel, paints, plastics, cements, masonry, sandstone, l
   limestone and marble.

Four natural processes which remove air pollutants from the atmosphere: 
1. Absorption by water ----      H₂O   + CO₂  --->   H₂CO₂
2. Rain out --------------------     CO₂ + H₂O   --->   H₂CO₂
3. Oxidation -------------------    2SO₂ + O₂    --->   2SO₃
4. Photosynthesis ----- -------- 6H₂O + 6CO₂ --->  C₆H₁₂O₆+ 6O₂

by which plants use the energy from sunlight to produce carbohydrate.

Air pollution control
1. The environmentally preferable strategy for controlling air pollution is to increase energy
    efficiency and conservation measures to reduce our use of fossil fuels;
2. Pollution reduction strategies must be tailored to the specific sources and types of
     pollutants in a given area.

Particulate control
1. Particulates generated from stationary sources are usually easier to control than are
    those from mobile sources;
2. Special measures must be taken to reduce particulates from fugitive stationary sources.

Automobile control
1. Exhaust recirculation and use of catalytic converters are the primary methods used to
    reduce automobile emissions of nitrogen oxides, carbon monoxide, and hydrocarbons;
2. Though pollution control devices are effective when new and properly maintained, their
    effectiveness diminishes over the life of the automobile; better inspection and
     enforcement programs could help address this problem;
3. Emphasis on the production of cleaner vehicles and reducing the vehicular traffic in large
     cities may help alleviate urban air pollution.

Sulfur dioxide control
1. Use of low-sulfur coal, coal washing, gasification, and emissions scrubbing can all reduce
    emissions of sulfur oxides from power plants, though not always without increased
     expense and environmental impact.

Soil remediation

Soil remediation is to remove pollution or contaminants (e.g., heavy metals, such as lead Pb, chromium Cr, arsenic As and cadmium Cd) from soil or sediment media. 

There are many soil remediation technologies. However they can be mainly categorised into: 
1. Ex-situ methods are excavation of affected soils and subsequent treatment at the surface.
2. In-situ methods deals with treatment of the contamination without removing the soils.

Remediation technologies can also be categorised:

Physical remediation

1. Thermal treatment - soil vapour extraction;

2. Soil washing.

Chemical remediation

1. Organic solvent extraction of organic contaminants, such as PCBs t from soils
2. Chemical oxidation - oxidants help to break organic contaminants down into harmless
     substances such as water and carbon dioxide.

Biological remediation -  a treatment process using microorganisms to break down, or degrade organic contaminants or toxic hazardous into less toxic or nontoxic substances, such as nitrogen N₂, carbon dioxide CO₂, and even water.

Phytoremediation -  in situ  use of plants to remediate contaminated soil, including
1. Rhizofiltration - accumulation of contaminants, such as toxic metals, by plant roots;
2. Phytoextraction - transportation and accumulation of contaminants, such as toxic metals, 
     in harvested plant shoots, trunks and leaves;
3. Phytotransformation - degradation of complex organic contaminants into simple
     molecules which are incorporated into plant tissues or are evaporated from plant tissues;
4. Phytostimulation - stimulation of microbial and fungal degradation by release of their
    exudates/enzymes around plant root zone

Phytoremediation is of:

1. Low cost,
2. Environmentally sound,
3. Equally protective of human health and the environment has been considered as a good
    alternative technique for cleaning contaminated soils.

Storm water management

Stormwater runoff, from agriculture, natural erosion lands, roadside and construction sites, often contains variety of contaminants, such as bacteria, toxic metals, nutrients causing eutrophication and automobile oils, which harm aquatic environment by lowering the amount of dissolved oxygen, decreasing organism's fertility and even abolishing some species.

An excessive sediment, for example,  in storm water runoff reduce the fresh water usefulness, contaminants, such as notably lead and most of the carbon-based toxic substances such as pesticides and polychlorinated biphenyls (PCB's) tend to adhere strongly to sediment particles in water, where they are transported from roadside into aquatic environment.

Stormwater management is important issue as how to moderates runoff risk through reducing peak flows (see the photo attached)

which indicates that metal concentration in storm water runoff decrease with rain events) by
1. addressing contaminant transport issues
2. characterising storm water runoff

3. estimating contaminant loads

4. designing stormwater improvement basins, online traps and wetlands

5. introducing drainage network flow capacity

6. improving storm water quality.

Storm water runoff management  techniques include

1. stormwater harvest through the use of underground storage tanks or retention ponds

2. infiltration through sustainable pavements (e.g. permeable paving),

3. bio-filtration or bio-retention though natural wetland or artificial wetland.

Renewable energy

Captain says that human activity is using up nature’s resources at rates beyond the capacity of nature to restore them. Since deriving energy from fossil fuels (coal, crude oil, oil shale, natural bitumen, peat and natural gas) is an unsustainable practice, utilization of renewable energy is core to sustainable development, which therefore becomes significance that human activity uses the natural resources in ways that allow regeneration for future use. 

Major forms of renewable energy, including, but are not limited:
• hydroelectricity;
• nuclear energy;
• solar energy - solar heating, photovoltaic electricity and solar thermal electricity
• biomass - wood, biofuels, forest residues, agricultural residues, livestock residues (manures), municipal soli waste, municipal bio-solids (sewage) and industrial waste;
• biomass based methanol and ethanol;
• hydrogen - hydrogen base fuel cell
• wind power;
• ocean energy, such as tidal, wave and ocean current;
• geothermal energy.

Organic agriculture

Organic agriculture is sustainable agriculture, where the farming acts in accordance with the principles of ecology, and the relationships between organisms and their environment are balanced.

Organic agriculture includes the following activities
1. Organic grain production
2. Organic vegetable production
3. Organic horticultural production
4. Organic livestock production
5. Organic fertilisers and pesticides

The primary benefits of organic agriculture are:
1. To satisfy human proteins, carbohydrates, and fiber needs;
2. To enhance environmental quality and the natural resource base upon which the
     agricultural economy depends;
3. To make the most efficient use of non-renewable resources and on-farm resources and
   integrate, where appropriate, natural biological cycles and controls;
4. To sustain the economic viability of agricultural operations;
5. To enhance the quality of life for farmers and society as a whole.

The organic industry is rapidly becoming a significant player in the global agricultural production scene. In 2012 the total farm-gate value of the organic industry in Australia was estimated to be $300.6 million with a total farm turnover of $432.2 million (Australian Organic Market Report, 2012).

With estimated annual growth of up to 20 per cent per year, the industry is fast moving away from its 'niche' industry status and into the mainstream agriculture. NSW DPI supports the industry in its growth and development, through providing expert advice and support.
NSW has an organic industry that consists of over 1000 accredited producers, with a farm gate value of over $108 million. The key organic products are fruit, vegetables, dairy, wheat and other cereals, soybeans, rice, wool, sheep meat, beef, wine and herbs.

Green chemistry

Green chemistry, also called sustainable chemistry, is a philosophy of chemical research and engineering that encourages the design of products and processes that minimize the use and generation of hazardous substances.

Whereas environmental chemistry is the chemistry of the natural environment, and of pollutant chemicals in nature, green chemistry seeks to reduce the negative impact of chemistry on the environment by preventing pollution at its source and using fewer natural resources.

Definition of green chemistry
1. To prevent environmental pollution,  minimize human impacts and sustain cycle of       ecosystem2. To apply innovative scientific solutions to real-world environmental problems
3. To find creative and innovative ways to reduce wastes, conserve energy, and discover
    replacements for hazardous substances
4. To introduce beneficial and environmental friendly economy
12 principles of green chemistry

1. Prevention
   It is better to prevent waste than to treat or clean up waste after it has been created.
2. Atom Economy
   Synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product.
3. Less Hazardous Chemical Syntheses
   Wherever practicable, synthetic methods should be designed to use and generate substances that possess little or no toxicity to human health and the environment.
4. Designing Safer Chemicals
   Chemical products should be designed to affect their desired function while minimizing their toxicity.
5. Safer Solvents and Auxiliaries
   The use of auxiliary substances (e.g., solvents, separation agents, etc.) should be made unnecessary wherever possible and innocuous when used.
6. Design for Energy Efficiency
   Energy requirements of chemical processes should be recognized for their environmental and economic impacts and should be minimized. If possible, synthetic methods should be conducted at ambient temperature and pressure.
7. Use of Renewable Feedstocks
   A raw material or feedstock should be renewable rather than depleting whenever technically and economically practicable.
8. Reduce Derivatives
   Unnecessary derivatization (use of blocking groups, protection/ deprotection, temporary modification of physical/chemical processes) should be minimized or avoided if possible, because such steps require additional reagents and can generate waste.
9. Catalysis
   Catalytic reagents (as selective as possible) are superior to stoichiometric reagents.
10. Design for Degradation
    Chemical products should be designed so that at the end of their function they break down into innocuous degradation products and do not persist in the environment.
11. Real-time analysis for Pollution Prevention
    Analytical methodologies need to be further developed to allow for real-time, in-process monitoring and control prior to the formation of hazardous substances.
12. Inherently Safer Chemistry for Accident Prevention
    Substances and the form of a substance used in a chemical process should be chosen to minimize the potential for chemical accidents, including releases, explosions, and fires.

Sewage treatment - wast water trement

Origin of sewage
sewage is generated by residential, institutional, commercial and then storm water runoff or urban runoff  events. 

Sewage treatment, which may also be referred to as waster water treatment,  is collectively, the processes to remove contaminants and reduce their concentration from waste water, which fits either (e.g., underground water, river, lake and creek treatment)  for drinking purposes or for be safely returning used water (residential, institutional, commercial) to the aquatic environment.
 

Substances that need to be removed include:

1. Volatile materials, causing air pollution

2. Color and turbidity, causing aesthetic problem and toxicities
3. Suspended solids, deposition of solid impairs aquatic life
4. Soluble organic matter, causing depletion of dissolved oxygen
5. Organic pollutants, causing tastes, odors and toxicities
6. Metals (mercury Hg, cadmium, Cd, lead Pb, chromium Cr, arsenic As) and cyanide,
    causing toxicity
7. Nitrogen, N and phosphorus P, causing eutrophication
8. Refractory substances resistant to biodegradation, toxic to aquatic life
9. Oil and floating materials

The processes of sewage treatment, in general, involves physical, chemical  and biological processes:

Physical treatment - membrane technologies, carbon adsorption, distillation, filtration, ion exchange, oil and grease skimming, oil/water separation, sedimentation, steam stripping, and solvent extraction;

Chemical treatment - chemical oxidation, chemical precipitation, chromium reduction, coagulation, cyanide destruction, dissolved air flotation, electrochemical oxidation, flocculation, hydrolysis and neutralization (pH control);

Biological treatment - using microorganisms to remove carbonaceous, Nitrogen N and sulphide S under either aerobic (either via oxidation or endogenous respiration) or anaerobic conditions via the following three applications:

1. Pond treatment

2. Activated sludge process

3. Biofilm process.

 

There are several process steps in a typical sewage treatment plant, as shown in the diagram given in Sewage treatment,

 

1. Pre-treatment  removes, by bar screening, all materials that can be easily collected from the raw sewage, including  trash, tree leaves/branches, and other large objects like cans, rags, plastic packets. Pre-treatment may include a sand or grit channel or chamber, where the velocity of the incoming sewage is adjusted to allow the settlement of sand, grit, stones and broken glass.

 

2. Primary treatment consists of temporarily holding the sewage in a quiescent basin where heavy solids can settle to the bottom while oil, grease and lighter solids float to the surface. The settled and floating materials are removed and the remaining liquid may be discharged or subjected to secondary treatment. Some sewage treatment plants that are connected to a combined sewer system have a bypass arrangement after the primary treatment unit. This means that during very heavy rainfall events, the secondary and tertiary treatment systems can be bypassed to protect them from hydraulic overloading, and the mixture of sewage and stormwater only receives primary treatment.
 

3. Secondary treatment removes dissolved and suspended biological matter, typically performed by indigenous, water-borne micro-organisms in a managed habitat. Secondary treatment may require a separation process to remove the micro-organisms from the treated water prior to discharge or tertiary treatment.
 

4. Tertiary treatment is sometimes defined as anything more than primary and secondary treatment in order to allow rejection into a highly sensitive or fragile ecosystem (estuaries, low-flow rivers, coral reefs,.). Treated water is sometimes disinfected chemically or physically (for example, by lagoons and microfiltration) prior to discharge into a stream, river, bay, lagoon or wetland, or it can be used for the irrigation of a golf course, green way or park. If it is sufficiently clean, it can also be used for groundwater recharge or agricultural purposes.

Stormwater quality assessmentt

Storm water runoff is a major non-point source pollution (the photo attached indicates that transportation is the one of the major sources of pollution along roadside) in the aquatic environment.

 

Storm water runoff contains many types of contaminants such as
1. Suspended particles;
2. Heavy metals (mercury Hg, cadmium, Cd, lead Pb, chromium Cr, arsenic As, copper Cu, nickel Ni, and zinc Zn)
3. Nutrients (nitrogen N, phosphorus P, and sulphur Si)
4. Hydrocarbons
5. Herbicides
6. Pesticides

which may be a significant health hazard to humans and aquatic organisms because it is largely untreated. 

The quality of stormwater (the photo attached indicates that a fish dead in creek during the first event of stormwater runoff) needs to be monitored in order to evaluate whether concentrations of pollutants (organics and inorganics) exceed regulatory limits in storm water runoff. The information provide some important information on strategies for controlling the quality of storm water runoff.
 

 

There are three Major techniques are often used in storm water runoff monitoring program, which include:

1. Chromatography - Ion chromatography (IC), Gas chromatography (GC/MS) and High 
     pressure liquid chromatography (HPLC)

2. Spectroscopy - UV-visible Spectroscopy, Fluorescence Spectroscopy 

3. Atomic spectrometry: Atomic Adsorption Spectrometry(AAS) and Inductively Coupled
    Plasma-Mass Spectrometry (ICP/MS).

Storm water quality assessment objectives:

1. Design cost-effective sampling and analysis procedures capable of meeting regulatory l
   limits for all constituents
2. Conduct field testing of the procedures to identify constituents that may
    exceed regulatory limits at a specific place (e.g., highways roadside).

The diagram (red line EPA limit of criterion continuous concentration in saltwater, and white line is rain precipitation) shows the concentration levels  of dissolved Cu monitored at two different roadsides during the storm water run off events, where the metal exceed the EPA limits in the most storm water run off events. 

Toxicity of stormwater can be assessed using 

!. Fish, such as young trout as photo shown left

2. Algae

3. Water flea

Toxicity of sediment in adjacent aquatic environment can be assessed using bivalves, such as:

1. Clam, the clam Macoma (as photo attached);

2. Cockle

3. Mussel

4. Cray fish

5. Sediment dwelling worm
 

Enrichment Factor (EF):

           EF = (M/Al)sample/(M/Al)reference
Where:
(M/Al)s = the ratio of metal and Al concentrations of a sample,
(M/Al)r = the ratio of metal and Al concentrations of a reference sediment, where the sediment has little history of  metal pollution.

Correlation, as diagram left shown, between total EF values and clam survival (p<0.002) indicates poor quality of the sediment assessed.

Inter-element relationships of Fe-Ni and Fe-Pb in clam tissues. Function of the MT/T couple as a homeostatic metal system: An increase in the amount of available Zn, or probably Fe, induces the synthesis of T through the action of the metal, leading to the formation of MT. An increase in the amount of available Thionein results in a bioaccumulation of the metals in clam tissues and tolerance of the clam towards the metals.