IB Environmental systems and societies 4.4 Water Pollution Key Definitions

Anoxia is the complete absence of dissolved oxygen.

Biochemical Oxygen Demand (BOD) is a key water quality parameter that measures the amount of dissolved oxygen required by microorganisms to break down organic material in water.

Biomagnification refers to the process by which the concentration of non-biodegradable pollutants increases as you move up trophic levels in a food chain or food web.

A biotic index is a quantitative score representing the health of an aquatic system, derived from the composition and abundance of pollution-sensitive and pollution-tolerant organisms.

An area in a water body where oxygen levels are too low to sustain most marine life

Endocrine disruptor is a chemical that interferes with the hormonal system, causing developmental, reproductive, or immune problems.

Eutrophication is a process where excess nutrients, primarily nitrates and phosphates, enter aquatic ecosystems, triggering a cascade of ecological changes.

A gyre is a large, rotating system of ocean currents that collects floating materials such as plastics into central “garbage patches.”

Hypoxia is a condition of severely reduced dissolved oxygen in a body of water.

Indicator species are organisms whose presence, absence, or abundance provides information about environmental conditions, particularly pollution levels.

Microplastics are small plastic particles, typically less than 5 millimeters in diameter, that result from the breakdown of larger plastic waste or are intentionally manufactured at that size.

A marine algal bloom, often reddish-brown, caused by dinoflagellates producing potent neurotoxins.

Sewage treatment refers to the multi-stage process that removes solid waste, organic matter, nutrients, and pathogens from wastewater before discharge into the environment.

Turbidity measures water transparency based on suspended particles (sediments, plankton, pollutants).

Water pollutants are substances or forms of energy that alter the physical, chemical, or biological characteristics of water, making it harmful for organisms and ecosystems.

Water pollution is the contamination of water bodies by harmful substances, making them unsafe for humans, wildlife, and ecosystems.

Water quality is a measure of the chemical, physical, and biological characteristics of water, determining its suitability for human consumption, agriculture, industry, and aquatic ecosystems.

The water quality index is a composite measure representing overall water quality, calculated by combining the results of several water tests with assigned weightings.