Sustainability Notes

1.         Food Supply

            a.         Humans have always used plants for food, shelter, and fire.

            b.         Early humans were not farmers. Instead they were hunters and gatherers who depended on wild plants and animals for their needs.

            c.         Agriculture did not appear until late in our history - around 10,000 years ago.

            d.         Currently, the human population is outgrowing our food supply:

                        i.         Year                Population

                                    1800                1 billion

                                    1930                2 billion

                                    1974                4 billion

                                    1999                6 billion

                                    2011                7 billion (projected)

            e.         The problem is there are more and more people but the same amount of land.

                        i.         60% of land is covered by ice, snow, deserts, or mountains.

                        ii.        30% is land we can farm on.

                        iii.       10% is covered with forests or is good only for grazing.

            f.         Approximately 24,000 children per day die of hunger.

            g.         Canada and the U.S. are the only countries which produce a consistent surplus of food.

            h.         Even still, the amount of food per person has been decreasing because usable land is decreasing. The growth of cities in North America uses 320 acres of farmland per hour and 3500 acres of forest per day.

            i.         Many highly populated areas don’t have the land to produce enough food. e.g., China has 22% of the population of the planet but only 5% of the land. North America has 5% of the population but 5% of the farmland.

            j.         Another problem is that not all farmland is of equal quality. It depends on nutrients, climate, precipitation, and length of season.

2.         Soil Formation and Loss

            a.         Soil is the thin layer on Earth’s surface that is created from the breakdown of organic matter.

            b.         The formation of a meter of soil may take between 100 and 100,000 years depending on the climate and other conditions.

                        i.         Soil forms fastest in climates with higher temperatures and more rainfall.

                        ii.        The rain provides water for decomposers and chemical reactions while these reactions are faster at higher temperatures.

            c.         Soil is necessary to grow plants (unless hydroponics is used) and the loss of soil will decrease crop yields.

            d.         The productivity of the soil can be affected by several factors.

                        i.         Deforestation leading to erosion.

                                    (1)       When tress are cut down, less rainfall is absorbed and runoff increases. This runoff washes away soil.

                                    (2)       Eroded soil often makes its way in streams and rivers to lakes or the ocean.

                                                (a)       It smothers fish eggs, kills tiny aquatic animals, and covers aquatic plants.

                        ii.        Heavy equipment

                                    (1)       Industrial farming uses heavy equipment which damages soil by compacting it. Compacted soil cannot absorb water well.

                                    (2)       Using heavy equipment allows us to put more land into food production. Farms tend to become large monoculture operations. As more land is farmed, erosion increases.

                        iii.       In developing countries, poor farmers face additional challenges:

                                    (1)       Low quality seeds.

                                    (2)       Poor irrigation.

                                    (3)       No fertilizer.

                                    (4)       Burning manure for fuel takes nutrients out of the soil.

            e.         How do we slow erosion?

                        i.         Contour planting - farmers plow and plant across the hill instead of up and down the hill.

                        ii.        Strip cropping - planting strips of crops that slow the speed of water.

                        iii.       Water ways - ditches are created and planted with grass to collect water and prevent it from eroding the soil.

                        iv.       Crop rotation - growing different crops in different years.

                        v.         Windbreaks - planting strips of tress to block the wind so it does not blow soil away.

                        vi.       Conservation tillage - reduces the amount of plowing done to decrease the amount of soil blown away and preserves the roots of plants to prevent erosion.

                        vii.      Cover crops - a crop is planted to protect the soil during winter.

3.         Irrigation is used to grow crops on farmland that would otherwise not receive enough water.

            a.         Irrigation water is used to grow crops for human consumption as well as to grow crops to feed to animals for meat production.

            b.         Most irrigation is done using water from groundwater sources which are non-renewable. When this water runs out, farming in these areas will be impossible. This will also affect our meat supply.

            c.         When irrigation water evaporates it leaves salt residue on the soil. The salt can accumulate and make it difficult for plants to grow.

4.         Hunger continues to be a major worldwide problem

            a.         Hunger and malnutrition are the number one risks to health worldwide.

            b.         1 in 6 people (1.02 billion) do not get enough food to be healthy.

            c.         Approximately 3.5 million children die every year from hunger (9600 per day).

            d.         This is despite the fact that the world produces more than enough food to feed everyone.

            e.         Worldwide hunger is one reason why it is important to preserve and improve our farmland.

            f.         How do we save farmland?

                        i.         Taxes - governments could lower taxes on undeveloped land so that people would slow development in order to save money.

                        ii.        Education - educating people helps them understand the importance of forests and wetlands.

                        iii.       Technology

                                    (1)       We can find ways to produce more food from the same amount of land.

                                    (2)       Producing better seeds and better machinery can improve the harvest as well.

            g.         Supplying enough protein is a major problem

                        i.         Most protein in our diet comes from meat but animals are higher on the food chain and energy is lost with each level of the food chain. Also, land for raising animals often comes from deforestation.

                                    (1)       A good deal of the beef sold in the US and Canada comes from Brazil and Central America because it is cheaper.

                                    (2)       Rain forest is burned so that cattle can be grazed on the land.

                                    (3)       The soil soon loses its nutrients so more forest has to be cut down to continue raising cattle.

                                    (4)       The current rate of deforestation in the Amazon is about 20,884 km² per year. This means an area the size of New Brunswick is cleared about every 3.5 years.

                        ii.        This is a problem in poor countries where people may not be able to afford animals. In these areas, most protein comes from plants.

                        iii.       There are several alternatives to meat.

                                    (1)       Fish can be grown in ponds by feeding them garbage.

                                    (2)       Soybeans are a good source of vegetable protein.

                                    (3)       Farmers could switch back to food crops rather than cash crops. A cash crop is something grown for sale rather than for food (e.g., tobacco, chocolate, drugs).

5.         Looking to the ocean as a source of food.

            a.         Nearly three quarters of the planet is covered by ocean so this could be a huge source of food.

            b.         Technology increased fishing yields for several years until the 1990s. Since then, catches of some species have remained the same while others have even declined. For some major species, 90% of the population is gone.

            c.         It is hard to tell how many fish there are so it is difficult to manage the fishery.

            d.         Increased coastal land development threatens fish population even further because runoff pollutes coastal waters.

            e.         Wetlands are being destroyed which allows more pollution to reach the ocean. Also, wetlands are the base of many food chains for deeper water. When the wetland is gone the fish population collapses.

6.         Pesticides

            a.         Pests are problems because of the way we farm:

                        i.         On farms, plants grow very close together making it ideal for insects.

                        ii.        Farmers usually grow only one type of crop which means one insect can destroy an entire crop.

                        iii.       Insects eat about 30% of a crop if no pesticides are used.

            b.         Insects become resistant to the chemical so more and more has to be used.

            c.         Some pesticides stay in the environment for a long time. Pesticide concentration increases as it moves up the food chain. This is called bioaccumulation.

            d.         Some pesticides kill beneficial insects as well as the harmful ones.

            e.         Lawns and golf courses can use 5x more chemicals per acre than farms and they don’t even produce food.

            f.         Pesticides are often washed off the plants and soil by rain and end up in the water.

            g.         Governments set acceptable levels for pesticide residues on foods but they are set for adults and not children. Children are at high risk also because a large part of their diet is fruit. In Canada, the government has banned or restricted many pesticides.

            h.         Alternatives

                        i.         Using natural predators such as wasps, lady bugs, fish, or birds.

                        ii.        Using living pesticides like bacteria, fungi, or viruses that naturally kill the insect.

                        iii.       Trapping insects to reduce the population.

                        iv.       Growing a variety of crops and using less crowded planting.

                        v.         Using biotechnology to develop resistant plants that don’t need pesticides.

                        vi.       Problems with alternatives

                                    (1)       They are expensive to develop.

                                    (2)       We don’t have alternatives for all pests.

                                    (3)       Farmers are not educated about alternatives.

                                    (4)       Chemicals are cheaper and faster.

7.         Water quality

            a.         Water quality is determined by a number of chemical, physical, and biological factors.

            b.         The intended use is important in determining water quality. For example, high quality drinking water would have 1.4 ppm chlorine in it which would kill most fish.

            c.         When substances are present in the water in amounts that are harmful to organisms living in or using the water, it is said to be polluted.

            d.         Water quality is also made difficult to measure because some chemicals are more dangerous when other chemicals are present. This is called the synergistic effect.

            e.         Dissolved oxygen.

                        i.         Aquatic organisms get oxygen by absorbing the oxygen that is dissolved in the water.

                        ii.        This oxygen enters the water from the atmosphere when water is mixed with air. This is why standing water has less oxygen dissolved in it.

                        iii.       Photosynthesis produces oxygen and so increases the dissolved oxygen in water.

                        iv.       Water that has organic matter in it has less dissolved oxygen because bacteria in the water use the oxygen.

                        v.         Temperature and dissolved oxygen.

                                    (1)       As water temperature increases, less oxygen is able to dissolve in it. Cooler water can hold more oxygen than warmer water.

            f.         pH

                        i.         Very few organisms can live in water with a pH lower than 4 or higher than 9.

                        ii.        Water can have minerals dissolved in it that can affect the pH.

                        iii.       Chemicals that affect the pH can also be added by accidental spills or mining.

            g.         Hardness is a measure of the minerals dissolved in the water.

                        i.         Soft water has few minerals while hard water has lots of minerals.

                        ii.        Remember that the hardness of the water can affect the pH because some minerals act as buffers.

            h.         Nitrates and nitrites.

                        i.         Most fertilizers contain nitrates and these are washed into the water when it rains.

                        ii.        Another major source is sewage produced by humans and other animals.

                        iii.       When nitrate is added to water, algae are able to grow quickly. When the algae die they are decomposed by bacteria and this uses up the dissolved oxygen.

            i.         Phosphates

                        i.         These also enter the water from fertilizers.

                        ii.        Phosphate-free detergents are now popular because we realize the danger of adding phosphates to water. The results are the same as adding nitrates.

8.         Water Treatment

            a.         Sewage was initially dumped directly into rivers. The problem with this practice is that waste water upstream is someone’s drinking water downstream.

            b.         Eventually, people built sewer systems to take sewage to the ocean. We thought this wouldn’t be a problem because the ocean is so large that the sewage would be diluted.

            c.         There are several problems with this:

                        i.         Fish and plants die, affecting food chains.

                        ii.        There is a health risk for humans. (e.g., uptown Saint John)

                        iii.       Water loses recreational value. (e.g., Meenan’s Cove beach)

            d.         Primary Treatment is the physical separation of large items.

                        i.         As sewage enters the sewage treatment plant it contains lots of things other than water and sewage.

                        ii.        The sewage passes through a screen or grill that separates large objects.

                        iii.       The solids (sludge) then settle into a tank and the scum is skimmed off the surface of the water (effluent).

            e.         Secondary Treatment removes solids and organic matter.

                        i.         In most areas this consists of bubbling air through the waste water to support the growth of bacteria.

                        ii.        The bacteria decompose most of the organic matter in the water.

                        iii.       The solids are again allowed to settle out.

                        iv.       Secondary treatment removes 90% of the organic waste.

            f.         Sludge digestion handles the sludge

                        i.         The sludge is usually heated or otherwise treated to kill microorganisms before it is either burned, buried, used as fertilizer, or turned into compost.

                        ii.        This sludge digestion produces methane which can be collected and used for energy.

            g.         Disinfection of water

                        i.         Chlorine is most often used to kill microbes that remain after secondary treatment.

                        ii.        If any organic matter is still present, cancer-causing chemicals called trihalomethanes (THM) are formed.

                        iii.       Although they are more expensive, ozone (O₃) or ultraviolet light (UV) can be used to sterilize the water.

            h.         Alternative water treatment ideas

                        i.         Wetlands can be used to treat water naturally. The drawback is that a lot of space is required so it can’t usually be used in cities.

                        ii.        Lagoons, or large pools, where air is bubbled into the water can speed up decomposition.

                        iii.       Waste water can be used to grow shellfish in aquaculture. They filter impurities out of the water and use the organic matter as food.

                        iv.       Septic tanks are used in rural areas or suburbs because space is usually available for the septic field.

9.         How do we get “more” water?

            a.         better treatment

            b.         use less water by conserving

            c.         reduce waste by repairing leaks

            d.         desalinate (take the salt out of) ocean water