Week 10: Urban Pollutants & Waste Management

What are contaminants, pollutants and the three pollution types?

Contaminant = substance above natural background levels.
Pollutant = contaminant causing harm.
Types: chemical (pesticides), physical (noise), biological (bacteria).

What are the main urban chemical pollutants and their pathways?

Pollutants: metals, POPs, pesticides, pharmaceuticals, microplastics and nutrients.
Point sources = identifiable outlets, such as wastewater/industrial discharge.
Non-point sources = diffuse urban, road and agricultural runoff

What are the sources and impacts of heavy metals?

Sources: mining, smelting, combustion, fertilisers, e-waste and batteries.
Persistent; accumulate in soils, sediments and organisms.
Effects: developmental/fertility problems, reduced biodiversity and impaired wildlife reproduction/behaviour.
Some are essential in small amounts but toxic at high concentrations

What are POPs and PFAS, and why are they harmful?

POPs: persistent, bioaccumulative, toxic chemicals—DDT, PCBs, dioxins and PFAS.
Sources: industry, waste combustion and past pesticide use.
Effects: hormone, development and immune-system disruption.
PFAS resist heat, grease, stains and water; difficult to break down and dispose of

How do bioaccumulation and biomagnification differ?

Bioaccumulation = build-up within an organism over time.
Biomagnification = increasing concentration up a food chain.
Example: tuna eat many PCB-contaminated fish.
Top predators are especially at risk (e.g. orcas)

How do pesticides affect ecosystems? Give a case study

Runoff, infiltration and misuse expose non-target species.
Effects: poisoning, reduced invertebrate diversity and threats to pollinators.
E.g. DDT → eggshell thinning → reproductive failure → raptor declines.
Challenge: balance food production with biodiversity protection

What are pharmaceutical sources, effects and a case study?

Sources: wastewater effluent and manufacturing discharge.
Drugs act on receptors also present in wildlife.
Effects: altered physiology, migration, reproduction and predator avoidance.
Diclofenac exposure in cattle → 95% vulture-population crash in South Asia

Melbourne waterways: pharmaceuticals found in aquatic invertebrates and riparian spiders.
Clobazam: exposed salmon had higher migration success than control fish, showing altered behaviour

What are the main plastic and microplastic concerns?

Most plastics persist beyond our lifetime; <10% recycled globally.
Microplastics = particles <5 mm.
Sources: fragments, microbeads, synthetic fibres and tyre wear.
Wildlife mistake plastics for food.

How does nutrient pollution harm waterways?

Excess nitrogen/phosphorus from runoff → eutrophication/algal blooms.
Dead algae decomposed by bacteria → oxygen depletion → hypoxia/anoxia → aquatic deaths.
Some blooms also release toxins.

What urban wastes are generated, and what risks do they create?

Household, construction/demolition and industrial waste.
Risks: persistent plastic litter, hazardous chemicals and limited landfill space.
Poorly lined landfills → leachate → groundwater/waterway contamination.

How can treatment and industry reduce pollution?

Advanced wastewater treatment: removes more micropollutants.
Wetlands: plants/microbes degrade some contaminants.
Cleaner production: prevent pollution at source.
Green chemistry: design less hazardous chemicals/processes.
Eco-efficiency: reduce material, water and energy use.

How can policy and infrastructure reduce urban waste?

Policy: reduction targets, circular economies, bans, landfill levies and deposit schemes.
Community: reduce, reuse and recycle.
Infrastructure: sorting/recycling, composting/biogas, waste-to-energy and methane capture.
Combine prevention, treatment, policy and individual action

Stockholm Convention: addresses POPs.
National Waste Policy Action Plan (2019).
Queensland Environmental Protection Act (1994) and Environmental Protection Policy Water (2009)