Science in Action 9: Environmental Chemistry

nitrogen cycle

process by which nitrogen is recycled between its various chemical forms

fuel combustion

process where fuel is burned in a chemical reaction

fertilizer

substance that enriches soil so that plants will grow better

pesticide

chemical used to kill pests

sewage

wastewater containing dissolved and undissolved materials from your kitchen, bathroom, and laundry

effluent

wastewater released from a factory or sewage treatment plant

septic tank

underground container in which bacteria break down organic materials in sewage before they are moved to the soil

sanitary landfill

a waste disposal facility where layers of compacted garbage are covered with layers of earth

acid

compound that dissolves in water to form a solution with a pH lower than 7

base

compound that dissolves in water to form a solution with a pH higher than 7

neutral

compound that dissolves in water to form a solution with a pH of 7

fats

type of lipid, stores energy

micronutrients

nutrients that organisms need in only minor or trace amounts

macronutrients

nutrients that organisms need in relatively large amounts

nutrients

elements and compounds that organisms need for living, growing, and reproducing

nucleic acids

largest and most complicated molecules in all the cells of living things; the two most important are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), made of phosphates, a simple sugar called ribose, and nitrogen-containing bases; have a major role in heredity and in controlling a cell's activities

minerals

inorganic elements, as calcium, iron, magnesium, potassium, or sodium that are essential to the functioning of the human body

optimum amounts

amount of a substance that provides an organism with the best health

amino acids

building blocks of proteins

enzyme

catalyst involved in chemical reactions in living things

diffusion

process in which molecules move from an area of higher concentration to one of lower concentration

carbohydrates

organic molecules made up of atoms of carbon, hydrogen, and oxygen (such as pasta, rice, potatoes, fruits, bread) caustic capable of burning, corroding, or destroying living tissue

fossil fuels

fuel formed from dead plants and animals; coal, oil, and natural gas

proteins

organic compound made up of units called amino acids; protein molecules contain atoms of nitrogen, hydrogen, oxygen, and carbon

root nodule

structure formed on the roots of certain plants where nitrogen-fixing bacteria live

nitrogen fixation

process of changing free nitrogen so that the nitrogen atoms can combine with other elements to form compounds that organisms can use; performed mainly by bacteria in the soil

vitamins

organic compound that is a micronutrient such as vitamin A, vitamin D, vitamin K, folic acid, and niacin

monitoring

keeping track of something for a specific purpose; certain chemicals are monitored in the environment to ensure they do not exceed safe levels

neutralization

reaction between an acid and a base that produces water and a solid compound called a salt

biological indicator

species that can be used to monitor the health of an environment

toxicity

how poisonous a substance is

heavy metals

metals that have a density of 5 or higher (such as copper, zinc, lead, mercury, cadmium, nickel); heavy metals are one type of substance monitored to determine water quality

dissolved oxygen

oxygen that is dissolved in water

invertebrate

animals without backbones

pollution

any change in the environment that produces a condition that is harmful to living things

pollutant

any material or form of energy that can cause harm to living organisms

photosynthesis

the process by which plants make food (It is a chemical process that uses sunlight to turn carbon dioxide into sugars the cell can use as energy.)

algae

large group of diverse organisms that use photosynthesis to produce food

nutrient pollution

the process by which too many nutrients, mainly nitrogen and phosphorus, are added to bodies of water causing excessive algae and plant growth

sewage outfall

the discharge point of a sewage waste stream into a body of water

run off

excess water from rain, snow melt, or other sources that flows over land and enters bodies of water such as oceans, streams, or rivers

acid rain

rain or any other form of precipitation that is has a pH of less than 5.6

toxic

poisonous

toxin

poison; substance that produces serious health problems or death when introduced into an organism

LD50

lethal dose 50; amount of a substance that causes 50% of a group of test animals to die if they are given a specified dose of the substance all at once

nitrogen oxides

NOx( g); major air pollutant; forms when nitrogen combines with oxygen as a result of fuel combustion; gives smog its characteristic brown colour; major source: motor vehicles

acid deposition

accumulation of acids or acidic compounds in lakes or streams on the surface of the Earth

ozone

colourless, odourless gas; at ground level, a pollutant produced as a result of industrial processes and the use of motor vehicles; high in the atmosphere, it forms a layer protecting Earth from the Sun's ultraviolet radiation

ozone layer

layer of ozone O3 (g) in the atmosphere 15 to 50 km above Earth's surface; protects Earth's surface from the Sun's ultraviolet radiation

greenhouse gases

gases in Earth's atmosphere that trap the heat that forms when radiant energy from the Sun reaches Earth's surface; water vapour, carbon dioxide, methane, and nitrogen oxide are all greenhouse gases

dispersion

scattering of a substance away from its source

deposition

the process in which substance is laid down

smog

smoke or other atmospheric pollutants combined with fog in an unhealthy or irritating mixture

surface water

water on the surface of the planet such as in a stream, river, lake, wetland, or ocean

groundwater

water that fills all the interconnected spaces in the soil

water table

top of the groundwater zone

pores

tiny spaces between soil grains or mineral grains in a rock; a substance with many pores is porous; if these pores are connected, a substance is permeable

leachate

liquid that dissolves and carries substances as it passes through soil

dilution

mixing of a substance with air or water; this reduces the substance's concentration

biodegradation

breakdown of materials by organisms such as earthworms, bacteria, and fungi; "bio-" refers to living things and "degrade" means to break up

phytoremediation

clean up of the environment using plants; "phyto-" means plant and "remediation" means cleanup; plants have been used to clean up metals, hydrocarbons, and other chemicals

photolysis

breakdown of compounds by sunlight; "photo" means light and "lysis" means break down

anaerobic

refers to processes or environments that do not require or contain oxygen ("an-" means without; "aero-" means "air")

aerobic

refers to processes or environments that require or contain oxygen ("aero-" means "air")

photodegradable

a substance capable of being broken down by light

bioaccumilation

occurs if a pollutant is picked by an organism and is not broken down or eliminated from its body

biomagnification

increase in concentration of a chemical or element as it moves up the food chain

WHMIS

Workplace Hazardous Materials Information System; a system of easy-to-see warning symbols on hazardous materials

pH scale

ranging from 0-14, 0-7 are acids, 7-14 are bases and 7 is neutral

organic compounds

compounds whose molecules contain carbon and hydrogen (such as fossil fuels),

inorganic compounds

compounds whose molecules do not contain both carbon and hydrogen

hydrogen ion

a hydrogen atom that loses an electron