18.3 Science, Technology, Society, Health & the Environment

Overview & Exam Relevance

Competency 003 of the TExES Core Subjects EC-6 Science exam focuses on the complex, reciprocal relationships connecting science, technology, society, and the environment (STSE). Science is not an isolated academic pursuit confined to sterile laboratories; it directly shapes, and is shaped by, human economic needs, ethical controversies, public policy, and environmental health. The Texas Essential Knowledge and Skills (TEKS) require elementary educators to guide students in recognizing the trade-offs inherent in technological innovation, analyzing renewable versus nonrenewable resources, and developing active conservation stewardship.

On the TExES 391 exam, questions evaluate your ability to evaluate energy transformation systems, assess the causes and consequences of human impact on the biosphere (such as the enhanced greenhouse effect, acid precipitation, and cultural eutrophication), and analyze environmental dynamics specific to Texas, including karst aquifer conservation, coastal wetland erosion, and invasive ecological disruptions.

---

The Reciprocal STSE Relationship

Science and technology are inextricably linked yet functionally distinct:

• Science: The systematic empirical pursuit of knowledge to understand and explain the natural universe through observation and experimentation ("Why does this happen?").
• Technology: The practical application of scientific knowledge to design tools, machines, systems, and processes that solve human problems and satisfy societal needs ("How can we do this better or faster?").

THE RECIPROCAL STSE FEEDBACK CYCLE

  ┌─────────────────────────────────────────────────────────────┐
  │ SCIENCE: Discovers natural principles and empirical laws   │
  └──────────────────────────────┬──────────────────────────────┘
                                 │ Stimulates new designs
                                 ▼
  ┌─────────────────────────────────────────────────────────────┐
  │ TECHNOLOGY: Creates tools, materials, and digital systems   │
  └──────────────────────────────┬──────────────────────────────┘
                                 │ Transforms human living
                                 ▼
  ┌─────────────────────────────────────────────────────────────┐
  │ SOCIETY: Establishes values, ethical laws, and funding      │
  └──────────────────────────────┬──────────────────────────────┘
                                 │ Dictates resource consumption
                                 ▼
  ┌─────────────────────────────────────────────────────────────┐
  │ ENVIRONMENT: Supplies natural resources & absorbs outputs   │
  └─────────────────────────────────────────────────────────────┘

Technological Trade-offs

Every technological innovation introduces both beneficial societal advancements and unintended environmental or human consequences. Teaching students to analyze trade-offs is a central TEKS requirement:

• Internal Combustion Engine: Revolutionized global transportation, supply-chain logistics, and economic growth; simultaneously generated atmospheric smog, greenhouse gas emissions, and geopolitical oil dependence.
• Synthetic Chemical Plastics: Provided sterile medical equipment, lightweight vehicles, and cheap food preservation; generated persistent macro- and microplastic contamination in terrestrial and marine ecosystems.
• Agricultural Fertilizers (Haber-Bosch Process): Synthetic nitrogen fixation doubled global agricultural yields, preventing widespread human famine; runoff into waterways generates catastrophic aquatic dead zones worldwide.

---

Natural Energy Resources: Renewable versus Nonrenewable

Energy resources are categorized based on their rate of natural replenishment relative to human consumption rates:

Renewable Energy Resources

Resources that are naturally replenished through continuous biogeochemical or physical cycles on a human timescale (days, months, or years) and will not be permanently exhausted if consumed sustainably:

1. Solar Energy: Radiative electromagnetic energy emitted by nuclear fusion inside the Sun. Converted directly into electricity via semiconductor photovoltaic (PV) cells or utilized as thermal energy via concentrating solar thermal mirrors. Advantages: Inexhaustible, produces zero emissions during operation. Limitations: Intermittent (depends on daylight and cloud cover); requires large land footprints and battery storage systems.
2. Wind Energy: Kinetic energy of moving air masses generated by the uneven solar heating of Earth's atmosphere. Moving air rotates turbine aerodynamic blades, spinning a mechanical generator to produce electrical current. Texas is the leading producer of wind energy in the United States, generating vast power across West Texas and coastal plains. Advantages: Low operational costs, zero greenhouse emissions. Limitations: Intermittent; poses collision risks to migratory avian and bat populations; aesthetic and noise concerns.
3. Hydroelectric Energy: Harnesses the gravitational potential energy of water stored behind dams in elevated reservoirs. Released water flows through penstocks, spinning hydroelectric turbines connected to generators. Advantages: Reliable, flexible base-load dispatchable power. Limitations: Dam construction inundates river valleys, alters water temperatures, disrupts sediment transport, and blocks migratory paths of anadromous fish.
4. Geothermal Energy: Exploits thermal energy stored deep within Earth's crust (derived from primordial planetary heat and radioactive decay of isotopes). Steam or superheated water extracted from geothermal wells drives steam turbines. Advantages: Constant, highly reliable baseload power unaffected by weather. Limitations: Geographically restricted to volcanically or tectonically active zones; risk of minor induced seismic tremors.
5. Biomass Energy: Chemical energy stored in organic biological materials, including wood, agricultural residues, switchgrass, and municipal organic waste. Converted into usable thermal energy via direct combustion or fermented into biofuels (ethanol from corn, biodiesel from soybeans). Advantages: Can be carbon-neutral if plant matter is replanted at the rate of harvest. Limitations: Releases particulate air pollution and $CO_2$ during combustion; large-scale biofuels compete with food agriculture for arable land and freshwater.

Nonrenewable Energy Resources

Resources that exist in fixed, finite geological quantities or form at geologic timescales spanning hundreds of millions of years. Once consumed, they cannot be replenished during human civilization:

1. Fossil Fuels:
   • Coal: Solid, carbon-rich combustible sedimentary rock formed from ancient terrestrial swamp plants buried under intense heat and pressure over hundreds of millions of years. Highest carbon emissions per unit of energy; releases toxic heavy metals (mercury, lead) and sulfur dioxide ($SO_2$).
   • Petroleum (Crude Oil): Liquid hydrocarbon mixture formed from the anaerobic decomposition of microscopic marine plankton and diatoms deposited in ancient ocean sediments. Refined through fractional distillation into gasoline, diesel, kerosene, and petrochemical feedstocks.
   • Natural Gas: Gaseous hydrocarbons consisting predominantly of methane ($CH_4$). Formed alongside petroleum deposits. Burns cleaner than coal and oil with lower $CO_2$ emissions per megawatt-hour; however, fugitive methane leaks during hydraulic fracturing ("fracking") and transport represent a greenhouse gas roughly 28 to 36 times more potent than $CO_2$ over a 100-year timescale.
2. Nuclear Energy (Uranium-235): Energy released through controlled nuclear fission in a reactor core. Heavy uranium nuclei are bombarded with neutrons, splitting into smaller fission fragments and releasing tremendous kinetic and thermal energy to boil water into turbine steam. Critical Classification Note: Nuclear energy produces zero direct greenhouse gas emissions during electrical generation, but uranium is a nonrenewable mineral resource because Earth contains a finite quantity of fissile uranium ore. Additionally, nuclear power creates long-lived radioactive spent fuel requiring centuries of secure deep geologic isolation.

---

Comparison of Renewable and Nonrenewable Energy Resources

---

Anthropogenic Impacts on Earth's Biosphere

Human activities alter biogeochemical cycles and destabilize ecological equilibrium in measurable ways:

The Combustion of Fossil Fuels & The Enhanced Greenhouse Effect

The natural greenhouse effect is essential to terrestrial life: greenhouse gases in the troposphere (water vapor $H_2O$, carbon dioxide $CO_2$, methane $CH_4$, nitrous oxide $N_2O$) absorb and re-emit outgoing infrared (thermal) radiation emitted by Earth's sun-warmed surface, keeping global average temperatures at a life-sustaining 15°C (59°F). Without this natural insulation, Earth's average surface temperature would plummet to a hostile -18°C (0°F).

However, the industrial-scale combustion of fossil fuels has driven atmospheric $CO_2$ concentrations from pre-industrial levels of ~280 ppm to over 420 ppm today. This produces the enhanced greenhouse effect: excessive greenhouse gas concentrations trap excess infrared energy within the lower atmosphere, driving anthropogenic global climate change, melting glacial and polar ice sheets, raising global sea levels through thermal water expansion and ice melt, and driving ocean acidification (as surplus atmospheric $CO_2$ dissolves into seawater, forming carbonic acid $H_2CO_3$, which depletes carbonate ions essential for corals, clams, and calcifying marine organisms).

Acid Precipitation (Acid Rain)

Acid rain forms when industrial emissions of sulfur dioxide ($SO_2$) (primarily from coal combustion) and nitrogen oxides ($NO_x$) (from motor vehicles and industrial boilers) react with atmospheric water vapor, oxygen, and chemical oxidants to synthesize dilute sulfuric acid ($H_2SO_4$) and nitric acid ($HNO_3$):

$SO_2 + H_2O \rightarrow H_2SO_3 \xrightarrow{[O]} H_2SO_4 \quad \text{and} \quad NO_x + H_2O \rightarrow HNO_3$

Normal, unpolluted rainfall has a slightly acidic pH of approximately 5.6 due to dissolved natural atmospheric $CO_2$ forming weak carbonic acid. Acid rain exhibits a pH below 5.0 (and frequently below 4.0). Its ecological impacts include:

• Forest Soil Degradation: Leaches essential plant micronutrients (calcium, magnesium) from the soil while mobilizing toxic aluminum ($Al^{3+}$) ions, stunting root growth and killing high-elevation forests.
• Aquatic Ecosystem Acidification: Drastically lowers the pH of lakes and streams, causing reproductive failure in amphibians and fish, and killing sensitive aquatic macroinvertebrates (mayflies, stoneflies).
• Structural Corrosion: Accelerates the chemical weathering and dissolution of calcium carbonate ($CaCO_3$) found in limestone buildings, marble statues, and historical monuments.

Cultural Eutrophication & Aquatic Dead Zones

THE MECHANISM OF CULTURAL EUTROPHICATION

[Agricultural Fertilizer Runoff (Nitrogen & Phosphorus)]
                        │
                        ▼
[Explosive Algal Bloom Overgrowth on Water Surface]
                        │
                        ▼
[Algae Block Sunlight -> Submerged Aquatic Plants Die]
                        │
                        ▼
[Algae Exhaust Nutrients and Die]
                        │
                        ▼
[Aerobic Decomposing Bacteria Multiply and Consume Oxygen]
                        │
                        ▼
[Dissolved Oxygen Depleted (Hypoxia / Anoxia)]
                        │
                        ▼
[Aquatic "Dead Zone" -> Fish & Shellfish Suffocate]

Cultural eutrophication is the accelerated nutrient enrichment of an aquatic ecosystem resulting from human runoff containing synthetic chemical fertilizers (rich in nitrates and phosphates), livestock manure from concentrated animal feeding operations, and untreated sewage. The ecological sequence is heavily tested:

1. Excess nitrates and phosphates enter a lake, pond, or coastal bay.
2. Algae and phytoplankton populations grow exponentially, forming dense surface algal blooms.
3. The thick surface layer of algae blocks sunlight from penetrating the water column, causing submerged photosynthetic vegetation to die.
4. Eventually, the algal bloom exhausts available nutrients and dies off in mass quantities.
5. Billions of aerobic decomposers (bacteria) feed on the dead plant and algal biomass. During cellular respiration, these bacteria consume immense quantities of dissolved oxygen ($DO$) from the water.
6. Dissolved oxygen levels plummet below lethal thresholds (<2 mg/L, termed hypoxia, or complete absence, anoxia), forming an aquatic dead zone where fish, crabs, and aquatic organisms suffocate and die.

Solid Waste Management: The 3Rs Hierarchy

The environmental waste management hierarchy specifies that prevention is far superior to disposal:

• 1. Reduce (Most Impactful): Minimizing consumption and manufacturing waste at the source (e.g., eliminating single-use packaging, designing durable goods).
• 2. Reuse: Using items repeatedly in their original form without reprocessing (e.g., refillable glass bottles, canvas grocery bags, repurposing containers).
• 3. Recycle: Reprocessing discarded materials (aluminum cans, cardboard, glass, specific PETE/HDPE plastics) into new consumer commodities. Recycling conserves virgin natural resources and saves energy (e.g., recycling aluminum saves 95% of the electrical energy required to smelt bauxite ore), but requires energy for collection and industrial remanufacturing.

---

Texas Environmental Science Contexts

The TExES 391 exam explicitly integrates environmental challenges unique to Texas geography and hydrogeology:

1. Water Conservation & Karst Aquifer Hydrogeology

Texas water supplies depend heavily upon underground aquifers. Two critical aquifers illustrate distinct conservation challenges:

• The Edwards Aquifer: A prominent karst aquifer in South Central Texas formed within highly soluble, fractured Cretaceous limestone. Karst hydrogeology is defined by porous limestone containing underground caverns, sinkholes, disappearing streams, and artesian springs (Comal Springs, San Marcos Springs). Because water moves rapidly through open fractures without the filtration provided by sand layers, the Edwards Aquifer features extraordinarily rapid recharge—and extreme vulnerability to non-point source pollution (petroleum runoff from urban parking lots, lawn fertilizers, and leaking septic tanks). It is the primary source of drinking water for more than two million people in the San Antonio region and sustains unique endemic endangered species, including the Texas blind salamander (Eurycea rathbuni) and fountain darter.
• The Ogallala Aquifer (High Plains Aquifer): A massive, unconfined sedimentary "fossil aquifer" underlying the Texas Panhandle and seven neighboring states. Unlike the Edwards, the Ogallala is recharged almost entirely by rainwater percolating through dense clay playa lakes at an extremely slow rate (millimeters per year). For decades, intensive center-pivot agricultural irrigation (cotton, grain sorghum, corn) has extracted groundwater at rates hundreds of times faster than natural recharge, causing catastrophic water-table drawdowns and threatening the agricultural viability of the Texas High Plains.

2. Coastal Wetland Erosion Along the Texas Gulf Coast

Texas Gulf Coast barrier islands (such as Galveston Island, Matagorda Island, and Padre Island) and coastal estuarine salt marshes are rapidly eroding due to three converging forces:

• Relative Sea-Level Rise: Driven by thermal expansion of warming ocean waters and global glacial ice melt.
• Subsidence: The physical sinking of coastal land caused by intense historical extraction of subterranean groundwater and petroleum deposits.
• Sediment Depletion: Dams constructed on inland Texas rivers (Brazos, Colorado, Trinity) trap sandy sediments upstream, preventing the natural replenishment of deltaic coastal wetlands.
• Ecological Consequence: Coastal wetlands serve as the primary reproductive nurseries for commercially vital fish, shrimp, and blue crabs, and act as indispensable natural physical storm buffers that absorb hurricane storm surges.

3. Historical Lessons: The Dust Bowl & Modern Soil Conservation

During the 1930s, the Texas Panhandle became the epicenter of the Dust Bowl. Severe, prolonged regional drought coincided with decades of aggressive mechanical deep-plowing that stripped away millions of acres of deep-rooted native shortgrass prairie sod (buffalo grass, blue grama). When the topsoil dried into powder, sustained High Plains winds blew millions of tons of topsoil into colossal airborne dust storms ("black blizzards"), destroying regional agriculture and creating an ecological catastrophe.

Modern agricultural science in Texas employs essential soil conservation methods:

• Contour Plowing: Plowing and planting across the natural slope contours of the land rather than up and down the hill. Furrows act as micro-dams that capture rainfall, preventing runoff and gully erosion.
• Terrace Farming: Constructing stepped, leveled ridges across steep hillsides to slow water velocity.
• Strip Cropping & Cover Crops: Alternating strips of erosion-prone row crops (cotton) with dense cover crops (clover, winter wheat) that physically anchor the topsoil year-round.
• Windbreaks / Shelterbelts: Planting dense linear rows of trees and shrubs along field boundaries perpendicular to prevailing winds, dramatically reducing wind velocity at ground level and halting aeolian soil erosion.

4. Invasive Species in Texas Ecosystems

Invasive species are non-native organisms introduced accidentally or deliberately into an ecosystem that rapidly proliferate and cause ecological, economic, or human health harm:

• Zebra Mussels (Dreissena polymorpha): Small freshwater mollusks originating from the Black and Caspian seas, transported into Texas lakes and rivers through recreational boat ballast and hulls. They reproduce prolifically, encrusting and clogging municipal water supply intake pipes, encrusting boat motors, and stripping the water column of microscopic phytoplankton through voracious filter feeding, causing native food webs to collapse.
• Feral Hogs (Sus scrofa): Prolific invasive mammals causing hundreds of millions of dollars in agricultural and ecological damage across Texas. Their destructive rooting behavior tears up native pastures, accelerates topsoil erosion along stream banks, degrades water quality with fecal coliform bacteria, and destroys ground nests of native birds (e.g., northern bobwhite quail).
• Saltcedar / Tamarisk (Tamarix spp.): Invasive shrubs introduced from Eurasia that have invaded West Texas rivers (Pecos River, Rio Grande). A single mature saltcedar can transpire up to 200 gallons of water per day, severely lowering the riparian water table, drying up springs, and concentrating salt on the surface soil to suppress native willows and cottonwoods.
• Red Imported Fire Ants (Solenopsis invicta): Introduced through the port of Mobile, Alabama, and established across Texas. They aggressively swarm and sting, displacing beneficial native ant species, preying upon ground-nesting birds, lizards, and small mammals, and damaging electrical junctions.

---

Science, Personal Health, and Informed Decisions

Competency 003 asks teachers to apply scientific principles to personal choices about fitness and health, including the effects and risks of substances.

• Physiological and psychological effects of substances: Nicotine (in cigarettes and vapes) is an addictive stimulant that raises heart rate and blood pressure and can harm the developing adolescent brain. Alcohol is a depressant that slows reaction time and impairs judgment. Caffeine is a stimulant that can disrupt sleep. Misusing medicines, including taking someone else's prescription, can cause serious harm. Dependence and addiction are both physical and psychological.
• Fitness and health science: Regular physical activity strengthens the heart and lungs, builds muscle and bone, and improves mood. Sleep and nutrition support growth and learning.
• Disease and medicine: Hand washing removes germs, vaccines prepare the immune system to fight specific diseases, and antibiotics treat bacterial infections but do not work against viruses such as the common cold. Overusing antibiotics contributes to antibiotic-resistant bacteria.
• Evaluating health claims: Students ask whether a claim is supported by evidence from controlled studies or only by advertising and testimonials.

---

Human Population Growth and Resource Use

• The world's population reached 8 billion in November 2022, according to the United Nations. Texas has more than 30 million residents and is one of the fastest-growing states.
• A growing population increases demand for water, energy, food, land, and housing, and produces more waste and pollution.
• Population change depends on births, deaths, and migration. Improvements in medicine, sanitation, and agriculture lowered death rates and allowed rapid population growth over the past two centuries.
• Responses include water conservation, recycling, renewable energy, efficient farming, and land-use planning, which connects science to decisions communities make.

---

Science and Scientists Helping Solve Problems

Scientists and engineers help resolve personal, societal, and global challenges, such as developing drought-tolerant crops, cleaner energy, flood-warning systems, and new medicines. The 2021 TEKS ask students to explain how discoveries and innovations affect society and to explore STEM careers through museums, libraries, professional organizations, online resources, and mentors.

---

Classroom Scenario Application

Classroom Context: Mr. Martinez's 4th-grade science class is investigating how human activities affect local aquatic ecosystems. The school is located near a small reservoir in Central Texas that recently experienced a major fish kill following several weeks of hot summer weather and heavy agricultural runoff.

Student Misconception: Several students suggest that the fish died because "the green algae poisoned the fish by biting them" or "the fertilizer in the water was poisonous like bug spray."

Pedagogical Intervention (Addressing Cultural Eutrophication):

1. Investigate Dissolved Oxygen: Mr. Martinez provides students with water quality test kits. Students measure dissolved oxygen ($DO$) in samples taken from a healthy, clear stream ($8\text{ mg/L}$) versus samples taken from the stagnant, algae-covered reservoir ($1.2\text{ mg/L}$). Students observe that the reservoir has critically low oxygen.
2. Model the Biological Mechanism: Using a graphic flowchart, Mr. Martinez guides the class to trace the chain of causality: Fertilizer runoff does not kill the fish directly; instead, it acts as plant food that causes an overgrowth of algae. When the algae die, microscopic bacteria eat the dead algae. Because bacteria are living organisms that respire, they use up the oxygen in the water. Without oxygen dissolved in the water, the fish cannot breathe through their gills.
3. Engineering Design Connection: Students design and model riparian buffer zones (planting grass and shrub strips along stream banks on a stream table) to demonstrate how terrestrial vegetation physically captures fertilizer runoff before it reaches water bodies.