Chemical Transport: Air & Groundwater

• Materials are transported through air, soil, and water
• Transportation of chemicals occurs in three stages in the air: release, dispersion, and deposition

Transportation of Chemicals: Air

• Release is the first stage and is when chemicals are released at the source
• Dispersion is the second stage, where chemicals scatter in various directions
• Deposition is the third stage, where chemicals are deposited in soil or water
• The direction and distance chemicals travel through the air is determined by pollutant properties, wind speed, prevailing wind direction, and precipitation
• Airborne chemicals are often an international concern because they can easily travel across borders
• Many countries have signed international agreements and passed anti-pollution laws to limit the spread of airborne pollutants

Transporting of Chemicals - Groundwater

• Groundwater fills all the spaces in the soil and does not contain any air
• The water table is the top of the groundwater zone
• The characteristics of groundwater prevent the dispersal of chemicals because contaminants cannot be easily dispersed due to the slow movement of groundwater
• Contaminants will become concentrated over time
• Pores are tiny spaces between soil grains
• The number of pores in the soil and the connections between them affect water movement
• Sometimes pores are tightly packed, disconnected, and water cannot move easily through the soil
• Minerals in rocks and soil, organic substances, heavy metals, fossil fuels, inorganic substances, micro-organisms, and household chemicals can contaminate groundwater

Transporting of Chemicals - Surface Water

• Contamination sources include air deposition, groundwater intrusion, runoff from agricultural and industrial sites, as well as outflow from storm sewers and sewage treatment plants
• Chemicals create problems when they do not disperse and concentrations increase locally
• Chemicals in low concentrations are dispersed easily which is not a problem

Problem Contaminants

• Exhibit properties such as low solubility, meaning that they do not easily dissolve in water, making them harder to remove
• Attach to soil and solids, binding to particles in water that settle in sediments
• Sink and accumulate, moving downward and collecting in lakes or riverbeds
• They often stay close to the pollution source, leading to higher concentrations nearby
• Remain persistent and long-lasting, remaining in the environment for years without breaking down easily
• Exhibit a nature that is difficult to clean up due to requiring specialized treatment methods for removal

Monitoring Water Sources

• Water sources need monitoring to ensure safe drinking water for many communities
• Monitoring also helps to identify pollutants like chemicals, bacteria, and heavy metals early
• Monitoring also helps trace pollution to the source from industries, agriculture, or natural causes, which helps in reducing or eliminating hazards by minimizing or removing pollutants
• Monitoring drinking water sources protect public health
• Monitoring drinking water sources maintains environmental sustainability by preserving water quality for future generations

Dealing with Water on the Ground and in Soil

• When water lands on a field or yard, it can evaporate, soak into the soil, run onto the street or into streams, and soak through the soil
• Hydrocarbons contaminating the soil are hard to clean up because they do not dissolve and are toxic to plants and animals
• Water that soaks into the soil and moves downwards is called leachate
• The composition of soil affects how fast pollutants are carried through it, which is called permeability
• Soil that is more permeable allows pollutants to move through faster, thus contaminating the soil and groundwater
• Soil with a large percentage of organic material results in slow movement of chemicals because the organic material absorbs them

Controlling Concentration

• Dispersion is the scattering of a substance away from its source, resulting in low concentrations over a larger area instead of a single high concentration
• Dilution reduces the concentration of a pollutant by mixing the polluting substance with large quantities of air or water
• A fast-flowing river or air mass can disperse or dilute a chemical very quickly

Cleaning the Environment Using Nature

Biodegradation describes the breakup/breakdown of pollutants by organisms

• These organisms include earthworms, bacteria, and fungi

Role of Bacteria

• Aerobic biodegradation exists in an environment containing oxygen
• Helpful for bacteria that need oxygen to reproduce and grow
• Anaerobic biodegradation exists in an environment with no oxygen
• This is helpful for some bacteria who thrive with little to no oxygen

Affecting Biodegradation Rate

• Temperature is just one factor that affects the biodegradation rate
• Other factors include soil moisture, pH, oxygen and nutrient supply

Decomposition

• Large organic molecules can be broken down (hydrolyzed) either inside or outside of bacteria
• Usually several steps are involved in the decomposition process

Phytoremediation

• Phytoremediation uses plants to remove harmful chemicals from the soil and reduces the concentration of such chemicals
• "Phyto" means plant and "remediation" means correction or cure
• Plants have been used to clean up metals, hydrocarbons, solvents, pesticides, radioactive materials, explosives, and landfill leachates
• Certain plants can absorb and accumulate (build-up) unusually large amounts of metals from the soil

Photolysis

• Photolysis is the degradation of some substances due to light exposure
• It involves the breakdown of compounds by sunlight
• An example is the breakdown of Nitrates and Ozone

Biomagnification

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

Oil Spills

• Changes in the composition of oil does occur after it is spilled
• The lighter and smaller molecules disperse into the air or water
• "Tar balls" of heavy hydrocarbons are washed ashore or sink into the sediment below the water
• Bacteria can degrade some of this oil for consumption
• Some hydrocarbons are toxic in concentrations as low as 1 ppb and persist in the environment for more than 10 years

Oil Spills – Effect on Plants and Animals

• Floating algae gets killed
• Invertebrates near the shore die due to decreased oxygen, loss of food, and hydrocarbons
• Fish become physically deformed
• The species can lose habitat and food resources
• Seabirds and mammals can become covered in toxic oil
• Oily feathers are no longer useful for protecting the birds

Oil Spills – Effect on Humans

• Commercial fishers were no longer able to fish
• People relied on wildlife for food and they had to buy expensive groceries from stores
• The tourist trade decreased because people chose to come to the contaminated area

Clean-up Following Oil Spills

• 50% of the oil is biodegraded/degraded in water
• 13% turns into Deposit in subtidal sediment
• 14% of the oil is recovered
• 20% of the oil is degraded by the light in the air
• 1% is dispersed into the water
• 2% ends up beached

Identifying Hazardous Products

• A product can be considered hazardous if it is toxic (poisonous), corrosive, flammable, or reactive

Reading Product Labels

• Material Safety Data Sheets (MSDS) provide critical information regarding product composition, characteristics, health effects, first aid procedures, and safe handling and storage instructions
• MSDS also provide material regarding proper disposal methods
• Product labels need to be kept original because of the information

Safe Storage

• Products need to be store in original containers
• Store things in cool, dry and well-ventilated areas
• Lock all product away from children and pets
• Different types of chemicals need to be kept separate
• Flammables also need to be stored away from heat sources
• A schedule needs to be in place for checking leaks or damage

Transporting product Safely

• Products need to be place upright and need to be secure
• They need to be kept away from where the passengers will be located
• Mixing different kinds of products also needs to be avoided

Disposal Methods

• Never pour chemicals down drains or soil
• Don't mix different products together
• Use designated hazardous waste collection sites
• Keep products in original containers when possible
• Always follow the local disposal guidelines

Environmental Impact

• Improper disposal can lead to groundwater contamination
• Improper disposal can lead to soil pollution
• Improper disposal can lead to harming wildlife and ecosystems
• Improper disposal can lead to air quality issues
• Take steps to reduce your household hazardous waste by making informed decisions