5.3 Environment Science & Engineering

5.3 Environment Science & Engineering

GEAS Environment Science and Engineering links engineering practice to ecological systems and sustainability. ECE-specific environmental concerns — e-waste, the energy use of communications infrastructure, and material restrictions — make this section directly relevant to the electronics profession.

1. Ecology & Natural Systems

• Ecosystem: a community of organisms interacting with their physical environment as a unit, exchanging energy and matter.
• Biotic components: producers (autotrophs/plants), consumers (herbivores, carnivores, omnivores), and decomposers (bacteria, fungi).
• Abiotic components: sunlight, temperature, water, air, soil, and minerals.
• Food chain / food web: energy flow from producers to consumers; only about 10% of energy transfers to the next trophic level (the 10% rule).
• Biogeochemical cycles: carbon, nitrogen, water (hydrologic), phosphorus, and sulfur cycles move elements between reservoirs.

Carrying Capacity & Population Dynamics

Carrying capacity ($K$) is the maximum population an environment can sustain indefinitely. Logistic growth models the approach to $K$: $\frac{dN}{dt} = rN\left(1 - \frac{N}{K}\right)$ where $r$ is the intrinsic growth rate and $N$ the population. Exponential (Malthusian) growth is the special case $K \to \infty$.

2. Natural Resources

Resources are classified by regenerability and depletion:

3. Environmental Concerns & Crises

• Air pollution: particulates (PM2.5/PM10), SOx, NOx, CO, ozone, and volatile organic compounds from combustion and industrial processes.
• Greenhouse effect & climate change: CO2, CH4, N2O, and fluorinated gases trap outgoing infrared radiation; the global warming potential (GWP) of methane is roughly 28 times CO2 over 100 years.
• Acid rain: SOx and NOx form sulfuric and nitric acids, lowering rain pH below about 5.6.
• Water pollution: biochemical oxygen demand (BOD), heavy metals, and eutrophication from nitrogen/phosphorus runoff.
• Ozone depletion: chlorofluorocarbons (CFCs) catalyze stratospheric ozone loss (addressed by the Montreal Protocol).
• Solid & hazardous waste: heavy-metal-laden electronics waste ("e-waste"), an ECE-sector responsibility.

E-Waste and the Electronics Industry

Discarded electronics contain lead (solder), mercury (lamps), cadmium (batteries), brominated flame retardants, and rare-earth elements. The Philippines regulates hazardous waste under DENR Administrative Order 2013-22 (Revised Procedures and Standards for the Management of Hazardous Wastes), and international trade in hazardous waste is governed by the Basel Convention.

4. Environmental Impact Assessment (EIA)

An EIA systematically predicts the environmental consequences of a proposed project before approval. Typical stages:

1. Screening — decide whether a project requires an EIA.
2. Scoping — identify which impacts to study.
3. Impact prediction & evaluation — quantify magnitude, duration, and significance.
4. Mitigation — design measures to avoid, reduce, or offset impacts.
5. Reporting — produce the Environmental Impact Statement (EIS).
6. Review & decision — agency approval with conditions.
7. Monitoring — verify compliance and actual impacts during and after construction.

In the Philippines, EIA is governed by PD 1586 (Establishing an Environmental Impact Statement System), which requires an Environmental Compliance Certificate (ECC) for projects in environmentally critical areas or projects of significant scale.

5. Sustainable Development

The Brundtland Commission (1987) defined sustainable development as "development that meets the needs of the present without compromising the ability of future generations to meet their own needs." Engineering practice applies this through:

• Green engineering: design for energy efficiency, low toxicity, recyclability, and minimal waste.
• Life-cycle assessment (LCA): quantify environmental impact from raw-material extraction through manufacture, use, and end-of-life (cradle-to-grave, or cradle-to-cradle when recycled).
• Circular economy: keep materials in use through reuse, remanufacturing, and recycling rather than a linear take-make-dispose model.
• Cleaner production: continuous application of preventive environmental strategy to processes and products.

Biochemical Oxygen Demand (BOD) and Water Quality

Biochemical oxygen demand (BOD) measures the dissolved oxygen consumed by aerobic microorganisms decomposing organic matter in a water sample, typically over five days at 20 degrees C (written BOD5). A low-BOD discharge indicates readily treatable, low-organic waste; a high-BOD discharge signals that a pollutant load will deplete receiving-water oxygen and stress aquatic life. A related metric, chemical oxygen demand (COD), uses a strong chemical oxidant and captures a broader (including non-biodegradable) organic load, so COD is always greater than or equal to BOD. Eutrophication — the over-enrichment of lakes and coastal waters by nitrogen and phosphorus from fertilizer runoff and sewage — causes algal blooms whose decay then collapses dissolved oxygen, a classic GEAS water-quality linkage. Heavy metals (lead, mercury, cadmium) are persistent and bioaccumulative rather than degradable, which is why they are regulated even at low concentrations.

ECE-Specific Environmental Responsibility

An Electronics Engineer's environmental exposure is concentrated at the end of life of the equipment the profession designs. A single discarded printed-circuit board can contain lead (solder), beryllium (connectors), mercury (lamps and switches), cadmium (older batteries), brominated flame retardants, and small amounts of rare-earth elements, all of which are hazardous if landfilled or informally burned. Responsible design therefore favours lead-free solder (per the RoHS philosophy), recyclable thermoplastic housings, fewer mixed materials, and clear disassembly paths so that recyclers can separate streams. The energy and carbon footprint of communications infrastructure — base stations, data centers, always-on network equipment — is increasingly an ECE concern, motivating high-efficiency amplifiers, sleep modes, and renewable-powered sites. RA 9292 itself frames ECE practice as serving the public welfare, which includes environmental protection, so GEAS questions may connect the law's scope to the sector's environmental duties.

Worked Example: 10% Rule and Energy Transfer

If producers in a field capture $10{,}000\text{ kJ}$ of energy through photosynthesis, only about $1{,}000\text{ kJ}$ reaches primary consumers (herbivores), about $100\text{ kJ}$ reaches secondary consumers, and only about $10\text{ kJ}$ reaches tertiary consumers. This roughly tenfold loss at each step explains why food chains rarely exceed four or five trophic levels and why top predators are scarce — the energy pyramid narrows much faster than the numbers pyramid. GEAS items use this to test both the ecological concept and simple proportional arithmetic.

6. Summary