After heavy rain, fertilizer washes from many farm fields into a lake. How is this pollution best classified?

A wastewater plant releases treated effluent through one labeled outfall pipe into a river. What type of pollution source is the pipe?

A sewage spill raises a stream's biochemical oxygen demand, and dissolved oxygen then falls. What process causes the oxygen decline?

Excess phosphorus enters a pond, algae multiply rapidly, and fish later die as oxygen falls. What process is occurring?

Water flowing out of an abandoned coal tunnel lowers a stream's pH and carries dissolved iron and other metals. What pollution process is most likely?

Construction removes vegetation from a hillside, and the adjacent stream becomes cloudy after storms. Which pollutant is chiefly causing the increased turbidity?

A power plant releases warmer water into a river. Why can this thermal pollution stress fish?

Repeated irrigation in a dry region leaves a white crust on the soil as water evaporates, and crop yields fall. What soil problem has developed?

Rainwater carries oil, brake dust, and road salt from many parking lots into a creek. What approach best reduces this source?

A city restores a riparian wetland below farm fields. Which measured change would best show that the wetland is filtering runoff?

Which vehicle-exhaust device uses metals such as platinum to change carbon monoxide, hydrocarbons, and nitrogen oxides into less harmful gases?

A coal-fired plant installs a limestone scrubber in its smokestack. Which pollutant does this device primarily target?

Which device removes fly ash from power-plant exhaust by attracting the particles to charged collection plates?

A factory passes its exhaust through rows of fabric tubes that trap fly ash before gases leave a stack. What device is this?

At a gasoline station, vapor-recovery equipment captures vapors while cars refuel. Which air pollutants does it reduce most directly?

A refinery routes an exhaust stream through activated carbon before release. Which contaminants are activated-carbon systems commonly used to adsorb?

A power plant adds selective catalytic reduction to its boiler exhaust. Which pollutant is the system intended to reduce?

A municipality requires low-sulfur fuel for its bus fleet. Which regional pollution problem does this policy most directly reduce?

Why do governments restrict chlorofluorocarbon releases from older refrigeration equipment?

A valley city has a cold air layer trapped beneath warmer air, and vehicle pollutants accumulate near the ground. What atmospheric condition is present?

Livestock digestion, rice cultivation, and landfills are major anthropogenic sources of which greenhouse gas?

Which greenhouse gas is strongly associated with fertilized agricultural soils and has a much higher 100-year warming potential than carbon dioxide?

Burning coal, oil, and natural gas most directly increases atmospheric concentrations of which gas?

In sunlight, nitrogen oxides and volatile organic compounds react to form which harmful secondary pollutant?

What is the greenhouse effect?

As Arctic sea ice melts, darker ocean water absorbs more sunlight and promotes additional warming. What type of climate feedback is this?

Why does increasing atmospheric carbon dioxide contribute to ocean acidification?

A coastal community elevates roads and buildings to reduce damage from future sea-level rise. Which type of climate response is this?

A utility replaces a coal generator with wind generation to reduce future carbon dioxide emissions. Which type of climate response is this?

Use the plotted series. During which interval did atmospheric CO₂ increase the most?

A city replaces dark asphalt roofs with reflective roofs. Which climate mechanism is the city trying to change?

Use the energy pyramid and the 10% rule. About how much energy is available to tertiary consumers?

A manufacturer redesigns a product to use less packaging before the product is made. Which waste-management strategy is this?

A school washes and refills durable water bottles instead of purchasing disposable bottles. Which option sits highest in the waste hierarchy?

Food scraps and yard trimmings are processed into a soil amendment under controlled biological conditions. What recovery method is being used?

A city burns nonrecyclable waste to generate electricity. Which trade-off is most accurate?

In a landfill without oxygen, microbes break down organic waste and release a greenhouse gas. Which gas is produced?

A modern landfill uses a low-permeability liner and leachate collection system. What hazard is this design intended to reduce?

A repair shop refurbishes discarded laptops so they can be used again. Compared with melting the materials for recycling, what is the primary advantage?

A county separates aluminum cans from mixed waste and remanufactures them into new cans. What waste-management process is this?

Why is source reduction generally preferred to recycling in the waste hierarchy?

A facility replaces a toxic solvent with a less toxic alternative before manufacturing begins. What is the main waste-prevention benefit?

A persistent fat-soluble pollutant is measured in algae, zooplankton, small fish, and eagles. Where should its concentration be greatest?

A fish absorbs mercury from water and retains it in its tissues over time. What process describes this buildup within one organism?

Two chemicals have LD₅₀ values of 20 mg/kg and 200 mg/kg in the same test organism. Which chemical is more toxic?

A homeowner tests an enclosed basement for radon. Why is this pollutant a health concern?

Why are young children especially vulnerable to lead exposure from paint dust or drinking water?

A person eats fish from a mercury-contaminated lake every week. What is the most direct exposure pathway?

A 1,000 kg soil sample contains 5 g of lead. What is the lead concentration in parts per million by mass?

A solvent spill contaminates a private well. When residents take hot showers, the solvent evaporates into the bathroom air. Which exposure route does this add?

A factory wants permission to discharge treated wastewater from a pipe into a river. Which federal law provides the NPDES permit framework?

Before approving a major federal highway project, an agency must evaluate environmental impacts and alternatives. Which law requires this review?

EPA seeks cleanup of an inactive hazardous-waste site where past disposal contaminated soil and groundwater. Which law is most directly used?

A company must track hazardous waste from its generation through transport, storage, treatment, and disposal. Which law establishes this cradle-to-grave system?

EPA sets national standards for major air pollutants and regulates emissions from stationary and mobile sources. Which statute supplies this authority?

A public water system must meet health-based drinking-water standards for contaminants. Which federal law applies?

Before a pesticide can be sold in the United States, it generally must be registered by EPA. Which law governs this requirement?

A federal agency must ensure that an action it funds or permits does not jeopardize a listed species or adversely modify its critical habitat. Which law applies?

An international agreement phases out substances that deplete the ozone layer, including many chlorofluorocarbons. Which treaty is this?

A power plant may trade allowances, but total sulfur dioxide emissions remain capped to reduce acid deposition. This program rests on which federal instrument?