1.1 Chemicals in the Environment

Overview Chemicals in the environment Nitrogen cycle Water, carbon dioxide, oxygen, sulfur dioxide, ammonia, nitrogen Nitrogen cycle Nitrogen fixation Biotic and abiotic factors responsible Factors that change the amount of nitrogen in the soil Agricultural activities Fertilizers and pesticides Industrial processes Natural gas and sour gas Processes and activities that affect environmental chemicals

Chemicals in the Environment Water (H2O) Source: water bodies (e.g. oceans, lakes, etc.) Role in the environment: hold life-supporting substances such as oxygen for organisms to breathe, required for photosynthesis and energy production Carbon dioxide (CO2) Source: product of respiration Role in the environment: required for photosynthesis Oxygen (O2) Source: product of photosynthesis, by-product of fuel combustion, forest fires Role in the environment: required for respiration

Chemicals in the Environment continued... Sulfur dioxide (SO2) Source: produced from fuel combustion, volcanoes, forest fires Ammonia (NH3) Source: nitrogen fixation from bacteria that combine ‘free’ atmospheric nitrogen with hydrogen and oxygen, lightening can also do this Nitrogen (N2) Source: atmosphere Role in the environment: required by living things to produce proteins such as enzymes, and structural components

Nitrogen Cycle The cycling of nitrogen through systems (e.g. the atmosphere, soil, plants, animals) Nitrogen fixation: the process of changing free nitrogen (N2) that exists in the atmosphere to nitrogen-containing molecules, such as NH3, that can be used by organisms Biotic factors: bacteria, nitrogen fixing plants (alfalfa, clover) Abiotic factors: lightening

Nitrogen Cycle Continued What factors change the amount of nitrogen in the soil? Amount of plant and animal waste that returns to the soil, and the activity of decomposers that break the materials down Water carrying nitrogen compounds away to other areas Presence of fertilizers or nitrogen fixing plants

Agricultural Activities Fertilizers Substance that enriches soil and improves plant growth e.g. N-P-K Pros: Improve plant growth from adding nutrients to the soil Cons: Too much fertilizer can hurt organisms Changes the concentrations of chemicals in water bodies

Agricultural Activities Pesticides Chemicals used to kill pests (organisms that harm people, crops, or structures) There are different types depending on the type of pest being controlled e.g. Herbicides (plants), insecticides (insects), and fungicides (funghi) The bertha armyworm is a major pest of canola Pros: Cons: At least 50% of the world’s food production would be lost to pests if we didn’t use pesticides Non-selective, i.e. may kill the pest and a non-pest The pesticide for armyworms also kills bees Some pests become resistant Some last for long periods in the environment e.g. DDT: banned in North America but still used in some places to control malaria-carrying mosquitos

Industrial Processes May release chemicals into the air Electrical power generation Mineral processing Fertilizer production A common industrial process in Alberta is natural gas processing

Natural Gas Natural gas is composed of compounds such as methane, ethane, propane, and butane Also contains nitrogen gas, carbon dioxide, hydrogen sulfide, helium, and trace metals such as mercury During processing, raw natural gas is purified by removing contaminants such as water, carbon dioxide, and hydrogen sulfide Processing separates its components which can be used for different things Methane, propane, and butane are used primarily for heating Ethane is used in plastics such as polyethylene

Sour Gas Sour gas is natural gas that contains large amount of the poisonous chemical, hydrogen sulfide Removing hydrogen sulfide produces sulfur dioxide gas and pure sulfur Natural processing plants in Alberta have been required to restrict these emissions since the 1970s 99% of the pure sulfur recovered is used to make sulfuric acid Sulfuric acid is used to make fertilizers, steel, synthetic fibers, and paints

Processes and Activities that Affect Environmental Chemicals Pollution: Any change in the environment that produces a condition that is harmful to living things

Solid Wastes: The garbage that is collected from households, industrial plants, commercial buildings, institutions, and construction and demolition sites Includes large items such as machinery, all the way to small items such as the caps on plastic drink bottles Potential pollution problems: dumped in landfills, where some hazardous waste may be burned, releasing pollutants Ways to reduce landfills: Composting, recycling

Hydrocarbons + O2 → CO2 + H2O + energy Waste Water/Sewage: Water containing dissolved and undissolved materials from your kitchen, bathroom, and laundry Potential pollution problems: goes directly into water bodies which then cause chemical changes that are harmful to aquatic life Fuel Combustion: Potential pollution problems: CO2 is a greenhouse gas that contributes to the heat absorption from the UV rays in the earth’s atmosphere Hydrocarbons + O2 → CO2 + H2O + energy (fossil fuels)

Natural gas processing: What can be done? Industrial processes Natural gas processing: Potential pollution problems: sulfur dioxide emissions What can be done? Law to reduce the allowable emissions Treating the SO2 before it is emitted to produce things that are less harmful Using fossil fuels that are lower in sulfur