3.6 - Human impact on the environment Flashcards

Question

Loss of habitat?

Answer 1

Deforestation Drainage of wetlands Hedgerow loss. e.g Hedgerows have separated fields for centuries. Provide a habitat for insects, nesting sites for birds + reptiles, food for many species and varying light intensity and water availability for diverse plants

Answer 2

wildlife corridors enabling reptiles, birds and mammals to move from one area to another, helping to maintain biodiversity. Their removal, often to accommodate the large agricultural machinery used in modern farming has destroyed large areas of this specialised habitat Herbivores and other consumers reduce in numbers with consequent reduction at higher trophic levels.

Answer 3

plants are an unsuitable height for the birds to build their nest led to a decrease of well known birds such as skylark and lapwing

Answer 4

Trophy Hunting - countries that allow this charge for privilege and claim old or sick animals are hunted Some traditional medical practices e.g use of tiger body parts, pangolian scales and rhino horn Bush meat industry - primates and others are killed for food Overfishing Agricultural exploitation

Answer 5

Dodo - was driven to extinction because rats were brought on european ships, ate the dodo eggs North American signal crayfish has invaded UK streams and rivers and the native crayfish which is smaller, is being outcompeted Red squirrels - have declined due to habitat loss and in many places, are being outcompeted by the north american grey squirrel

Answer 6

Oil is shipped worldwide in supertankers, some of which = to big ever to enter a port. Therefore, accidental discharge of oil into the sea occurs for example Torey canyon disaster between Cornwall and isles of Sicily in 1967 exon valdez disaster off coast of Alaska in 1989 : largest petrol spill in fresh water was from a royal dutch tank ship. estrella near the coast of Argentina. Polluted the environment, contaminated drinking water and killed plants and animals

Answer 7

prevents oxygenation of surface water. Animals break through the surface are covered by a film of oil. Birds, subsequently are chilled to death because their feathers are clumped together and cannot provide insulation. Oil is washed up on beaches is ingested by shore dwelling animals which are poisoned by it

Answer 8

polychlorinated biphenyls. Artificial substances which have accumulated in the food chain and so are ingested in some foods containing animal products. Neurotoxins, carcinogens and hormone disruptions, their use was progressively banned in the UK between 1981 and 2000

Answer 9

the protection, preservation, management, restoration of natural habitats and their ecological communities to enhance biodiversity while allowing for suitable human activity

Answer 10

Protecting habitats International co operation Gene banks Education Legislation Ecotourism

Answer 11

protects the species that live there and communities act as living gene banks. Official designation recognises local nature reserves, sometimes as small as a few hectares. Larger, national nature reserves such as the Gower Coast, SAC'S, ( Special areas of conservation) SSSI ( sites of special scientific interest)such as the brecon bog and other sites. Have varying levels of legal protection and may be managed and monitored by wardens.

Answer 12

restricting trade in ivory and whaling. International law allows some countries to practise scientific whaling but many consider the term scientific to be disingenuous and there are organised attempts to stop it from happening

Answer 13

Endangered species are protected and entered into breeding programmes in specalised zoos and botanic gardens. Pandas are held in great affection and attempts by zoos to persuade them to breed Records of matings ate kept so geentic diversity can be increasesd by deliberate choice of parents.

Answer 14

used to store genes of economically important animals and of threatened species. Rather than moving animals, sperm samples can be sent arounf the world to use in breeding programmes in other zoos.

Answer 15

maintain stocks of seeds of traditional varieties and of vulnerable species in highly controlled conditions, liquid nitrogen. Although plant fro a 2000 year old judean date palm seed has successfully grown, seeds degrade over time. So periodically, samples are thawed and germinated. Seed banks in some countries have very high levels of protection as they are viewed as a potential source of food in case of catastrophic environmental degradation

Answer 16

older, less commercial varieties for special characteristics, e.g hardiness and wool production

Answer 17

Red kite in mid-wales the chough in cornwall, the Arabian oryx in Israel and Jordan, the giant condor in California and the Przewalski horse in Mongolia have all been driven to the brink of extinction. Following successful breeding programmes have been reintroduced to their former habitats

Answer 18

Global organisations such as he World Wide Fund for nature, mount public awareness campaigns/ Natural resources wales is a government body promoting nature conservation. It advises government and groups whose activities affect wildlife and their habitats It produces publications, proposes ecosystem management of schemes and establishes nature reserves.

Answer 19

The EU habitats directive has imposed a range of measures to protect habitats and enhance biodiversity throughout Europe, preventing overglazing, overfishing,hunting of game, collection of birds eggs, picking of wild flowers and plant collecting

Answer 20

Responsible travel to natural areas that conserves the environment and improves the well-being of local people

Answer 21

that mass travel is harmful globally and to specific habitats. It aims to: Contribute to conservation efforts Employ local people and give money back to local communities Educate visitors about local environment and culture Cooperate with local people to manage natural areas.

Answer 22

Ethical reasons Agriculture Potential medical uses

Answer 23

each species represents a particular combination of genes and alleles adapted to a particular environment and ir is considered that the uniqueness of each is intrinsically valuable

Answer 24

plants + animals used in agriculture and horticulture have been developed from those in the wild. Selective breeding increases genetic uniformity, with the loss of rarer alleles. In the past, breeders may have neglected some important qualities such as resistance to cold or disease. They need to be bred back into cultivated varieties, using the wild plants and animals as a gene bank. If habitats and the wildlife that live in them are threatened, it may no longer be possible.

Answer 25

some alleles will provide an advantage to the individuals that carry them and those individuals will be selected for, preventing the extinction of that species

Answer 26

Antibiotics we use are derived largely from fungi but may other of our medicinal drugs are synthesised by plants. e.g quinine - extracted from the bark of cinchona, an amazon rainforest tree used to treat malaria.

Answer 27

to produce the quantitiy and quality of food required to feed the increasing human population.

Answer 28

many hedgerows were removed to make larger fields to enable machinery to prepare the soil and harvest crops Larger fields = used for monoculture, where single crops breeds or varieties e.g wheat or barley are grown over a large area. With mixed crops, there are many different microhabitats and so many different plants and therefore, many different animals could live there.

Answer 29

the agricultural practice of growing of a single crop, breed or variety over a large area

Answer 30

Yield progressively declines because: The root are always the same length, so they extract the same minerals from the depth of the soil. Intensive cultivation has therefore hugely increases the use of inorganic fertilisers Same crop = always susceptible to same pests, which increase in number, so more intesticides, herbicides and fungicides are used.

Answer 31

causes grassland to become unsuitable Their hooves compact the sil, driving out the air, preventing water from draining through. Roots cannot penetrate the soil and so grass for grazing cannot grow.

Answer 32

Widespread because timber is used extensively both as a building material and as fuel, as well as providing paper and packaging. Land is also cleared for farming, often to produce biofuels or grazing for the cattle destined for the meat industry. Specific high value trees, such as teak or mahogany may be targeted and felling and removing them damages many others in the process.

Answer 33

soil erosion Deforestation of uplands causes lowland flooding

Answer 34

the removal of topsoil which contains valuable nutrients

Answer 35

roots bind soil together. Deforestation on the higher slopes of valleys allow heavy rain to sweep exposed topsoil down to the flood plains below.

Answer 36

fertile soil and what remains is not suitable for crop growth

Answer 37

on the lower slopes, plant, humus and leaf litter act as a sponge, soaking up heavy rainfall and water is only gradually released into the soil. Trees transpire and return water to the atmosphere.

Answer 38

there are no plants and water evaporates from the soil. Diminishing the quality of the soil.

Answer 39

returns water vapour to the atmosphere more slowly than transpiration so soil on deforested land becomes water. Water fills the soil's airspaces and so the oxygen available for roots decreases. It takes longer for a wet soil to warm up than a dry soil, so these soils are also cold. Germination and root activity are reduced. Cold, damp soil favours the growth of denitrifying bacteria and so soil loses its nitrates and therefore fertility.

Answer 40

water only returns to the atmosphere by evaporation from the spil, not by transpiration and evaporation is slow. Accelerates desertification.

Answer 41

estimated that 50 % of the Earth's species live in the tropical rainforests, which cover only about 10 % of the Earth's land area. Destruction of such natural habitats may lead to the loss of some tropical species. They may become extinct before their clinical properties have been investigated. Estimated that every day, rainforest deforestation makes 25 plant and animal species extinct.

Answer 42

as photosynthesising trees are cut down, the removal of CO2 from the atmosphere by photosynthesis is decreased. Cut trees may be burned, or left to decay, releasing CO2 in the atmosphere.

Answer 43

small forest is cut and burned. People grow crops on soil fertilised with ash from the burned trees. When soil = no longer fertile, people leave and are regenerates. Sustainable on a small scale but not a large scale

Answer 44

Cutting down of trees close to the ground and leaving them deveral years to regrow

Answer 45

a tree trunk is cut, leaving a stool a few cm high. New shoots emerge from the buds in the stool and grow into poles, which thicken over the years. Poles can be cut on rotation to produce the timber of different widths. Coppiced plants can regenerate over long period of time

Answer 46

as many years are left between harvesting adjacent areas of forest and a variety of habitats develop, favouring diverse wildlife.

Answer 47

instead of removing all the trees in one area at one time, is used. Valuable on steep slopes where the total removal of trees would leave the soil very vulnerable to erosion. Also helps to maintain nutrients in the forest soil and minimises the amount of soil that is washed into nearby waterways.

Answer 48

By planting trees the optimum distance apart. If too close, intra specific competition occurs and the trees grow tall and thin, producing poor quality timber. Controlling pests and diseases, so the trees grow well, producing high quality timber. Fewer trees need to be felled and best use is made of land, reducing total area required. Cutting a similar number of trees each year for long periods of time, allows the forest ecosystem to be maintained. Habitats are left intact and species are able to live in the forest even though timber is being extracted

Answer 49

There is a need to plant more native species to provide a wide range of habitats for the great variety of species that live there

Answer 50

rate at which fish are harvested exceeds the rate at which they reproduce

Answer 51

nets with a small mesh catch young fish before they have become sexually mature. Means that as time goes by, there are fewer individuals left to reproduce and the population size decreases. May be harder for the remaining fish to find a mate with a smaller fish reproducing. the genetic diversity of the population decreases

Answer 52

Drift netting Trawling

Answer 53

Pelagic fish live in surface waters. They swim into a net, suspended from floats, stretched between 2 boats. But with thousands of miles of nets, non -target species e.g dolphins and marine turtles become trapped

Answer 54

fish that live deeper in water, the mid and bottom feeders, are caught by a large net which is dragged through the water, catching whatever swims into it Equipment used in trawling has damaged the ocean bed, destroying the habitats of molluscs such as clams, and other organisms, putting their populations at risk

Answer 55

when trawlers spread their nets, they catch a fish called capelin which are not eaten by humans but are important prey species for cod, so removing them from the sea contributes to the decline of cod stocks. 6 countries including Japan and Russia have harvested Antarctic krill 50 mm long shrimp form swarms many miles cross Primary consumers, eating phytoplankton. Main food of whales and they supplement the diets of seals, penguins, squid and fish. Ecological balance in the Antarctic has already been upset by overexploitation of whales, heavy fishing of krill with badly affect the rest of their food web, including the remaining whales.

Answer 56

damages the livelihoods of fisherman. a balance must be struck between catching enough fish to make a living whilst also ensuring there are enough breeding fish to replenish stocks.

Answer 57

The mesh size of the nets but must be large enough that young fish can swim through and survive. Supported by legislation that prevents selling fish below a certain size. Quotas can be set so that only a certain mass of fish may be brought to land. Exclusion zones prohibit fishing in defined areas at certain times of the year, allowing the fish to reproduce. Position of fishing trawlers can be monitored by satellite technology and fines can be imposed for non compliance/ Consumers may choose to eat only those fish certified by the Marine stewardship council, which ensures fish are taken from sustainable sources

Answer 58

controlling the size of fishing fleets controlling the numbers of days spent at sea fish farming may reduce overfishing

Answer 59

Salmon and trout that we eat are from aquaculture most commonly farmed fish can be bred and grown to maturity in ponds, lakes and managed enclosures in estuaries, where predation is reduced and food supplies are maintained

Answer 60

the growth of phytoplankton can be increased by the addition of artificial fertilisers to the water Fish grow rapidly when they are reared in the warm waters discharged from factories. Fish are sometimes farmed in a pod, a large steerable device, which can be moved depending on prevailing ocean currents, on local water temperature and other abiotic factors

Answer 61

Fish convert their food into protein more efficiently A greater proportion of fishes' bodies are edible Fish farming has a lower carbon footprint

Answer 62

Diseased fish Pollution Escaped fish Environmental toxins Environmental degradation

Answer 63

farmed salmon are often very densely stocked and so they can easily transmit disease. In Norwegian fish farms, antibiotic use is low as salmon are vaccinated, but elsewhere, high doses of antibiotic are required to keep them moderately healthy.

Answer 64

to control fish parasites, such as sea lice, known to harm marine invertebrates, especially molluscs

Answer 65

the ecological balance of the waterways may be upset . Eutrophication, for example can result when fish excreta, waste food and fertiliser are carried into the water around the rearing pens

Answer 66

farmed fish have been selected for very rapid growth. If they escape out-compete wild fish for food, habitat and mates. They also transmit parasites and other infections. Escaped farmed fish interbreed with wild fish and set up fast grown populations which can push wild fish to extinction

Answer 67

e.g PCBs, dioxins and pesticides are more concentrated in farmed than wild salmon, although their concentrations are so small that their effects do not outweigh the health benefits of eating fish

Answer 68

the shrimp industry in particular have been blamed for their salinisation of soil and groundwater and the destruction of the mangroves that normally protect coastal communities from tropical storms.

Answer 69

the quality of the environment establishes the current status and when done repeatedly, the pattern of the data can be used to identify trends and make predictions.

Answer 70

concentrations of air pollutions are measured because of the health effects associated with exposure to them.

Answer 71

by the wind, so this must be taken into account when identifying sources of pollution. Species of lichens on rocks and trees indicate the relative level of air pollution.

Answer 72

looks at soil structure and density, its water-holding and drainage capacity,pH, organic particles, earthworms and other organisms. Lichens can indicate the type and severity of heavy metal contamination

Answer 73

chemical, biological and microbiological

Answer 74

acid rain and greenhouse gases have made water monitoring essential because of their potential to do harm. Concentration of environmental oestrogens in water supplies has increased, as a result of the use of oral contraceptives and of materials used in industry. They have a feminising effect on some aquatic organisms and it is suspected that they may influence humans as well, both in embryo development and in timing of puberty

Answer 75

many animals act as an indicator species for water quality. e.g brown trout in rivers indicate high quality water. Mosses can indicate heavy metal concentrations. Eels are used to study halogenated organic chemicals, which accumulate in their fat.

Answer 76

bacteria and viruses are monitored, especially in drinking water or water used for sports. Many sewage treatment plants do not sterilise the water they release. So water entering a river may look clean but could still have a very high bacterial count. Most will be harmless coliform bacteria but if E.coli or coliform counts are high, water will be tested for other, specific pathogens and treated.

Answer 77

means that data colected can contribute to environmental impact assessments these are documents that aim to predict environmental effects of a proposed project when activities risk harming the enbironment

Answer 78

a description of the project and site alternatives that have been considered e.g whether the fuel in a power station burning biomass is local or not A description of the environment, e.g populations, fauna, flora, air,soilwater,human use,landscape and cultural heritage. Organisations with crucial local knowledge, such as the RSPB have input into this A description of significant effects of proposed project on the environment, e.g in a wind farm deveopment, a significant impact may be collisions of birds with the blades of wind turbines Mitigation - ways to avoid negative impacs essential aspect of planning evidence is required to show that reducing the impact of harmful activities has been considered.

Answer 79

wind farms to be built when birds are not nesting Proposed roads to avoid breeding ponds of endangered amiphibians e.g the greater crested newt and the natterjack toad

Answer 80

limits which global systems must operate to prevent abrupt and irreversible environmental change

Answer 81

introduced in 2009 as a way of defining the safe operating space for humanity 9 global processes have been identified, that regulate the stability of planetary systems and the interactions of air, land and sea,

Answer 82

common way of displaying the status of planetary systems.

Answer 83

safe operating space

Answer 84

zone of uncertainty

Answer 85

represents high risk planetary boundary has been crossed and events are predictable

Answer 86

one of the 2 core boundaries and its planetary boundary has been crossed

Answer 87

crossing this planetary boundary would drive the earth into a new and unpredictable state with severe consequence for the biosphere

Answer 88

a fuel made by a biological processes such as anaerobic digestion rather than by geological processes such as long-term heat and compression that formed fossil fuels

Answer 89

to contribute to reduction in fossil fuel combustion

Answer 90

removes the carbon dioxide from the atmosphere again this contrasts with fossil fuels which release carbon laid down hundreds of millions of years ago

Answer 91

by biological processes such as anaerobic digestion of plant material of agricultural, domestic and industrial waste.

Answer 92

in reducing the use of fossil fuels but growing plant material for them conflicts with the use of land for food production and it requires considerable irrigation.

Answer 93

the sugars and vegetable oils found in arable crops, which are easily extracted with conventional technology.

Answer 94

cellulose and lignin from woody crops which are harder to extract

Answer 95

Food versus fuel debate sustainable biofuel production deforestation reduction in water availability combustion of biodiesel

Answer 96

land used to grow food has been turned over to crop production for biofuels, e.g palm oil, so people have less food to eat or to export. An additional problem - energy crops are often to grow in monoculture

Answer 97

relies on sustainable planting and efficient technical systems

Answer 98

because biofuel crops require a large volume of irrigation water

Answer 99

produces more nitrous oxide, a greenhouse gas, than fossil fuels

Answer 100

is the commonest biofuel and most petrol engines are designed to use up 15% bioethanol with petrol

Answer 101

by fermenting the carbohydrates in sugar or starch crops, such as maize sugar beets, sugar cane and sweet sorghum Brazil and the USA have developed bioethanol commercial with 90% of global production

Answer 102

plant material is crushed and the stored starches are digested with carbohydrases to release sugars Sucrose = crystallised out leaving molasses, which is rich in glucose and fructose Glucose + fructose are fermented by yeast to produces a mixture containing ethanol Mixture is heated by burning the fibrous waste, or bagasse, from the initial plant material and pure ethanol is distilled

Answer 103

most widely spread biofuel in europe. made from vegetale oils includong soya, rapeseed and palm oil and it can be made from algae. These crops are grown for their long chain fatty acid content.

Answer 104

an alcohol, commonly methanol to produce methyl linoleate, also called methyl ester or biodiesel

Answer 105

methanol + linoleic acid -- methyl linoleate + water

Answer 106

biodiesel contains less carbon and more hydrogen and oxygen than petrodiesel so when pure - produces about 60% of CO2 emissions. also releases fewer carbon particles and less carbon monoxide but produces more nitrous oxide, Pure biodiesel can be used in car engines, however it is usually mixed with diesel to reduce pollution

Answer 107

is a mixture of gases, comprising approximately 60 % methane and 40 % carbon dioxide. It is made by bacterial digestion of biodegradable waste materials, such as animals and human waste, ot energy.

Answer 108

1) macromolecules in the waste material are aerobically digested by amylases, proteases and lipases to sugars, amino acids, fatty acids and glycerol respectively 2) Acetogenesis is an aerobic process that produces short chain fatty acids, especially ethanoic acid. Carbon monoxide and hydrogen gas are produced as the oxygen gas is used up 3)Methanogenesis is an anaerobic process C6H1206 ---- 3CH4+3C02 solid material that is left over is dried and used as a biofuel or fertiliser

Answer 109

around the world as industrial installations and notably in India and in China, in domestic digesters

Answer 110

through naturally occurring processes at landfill sites. It can be tapped off for use as a fuel. If it is left to escape into the atmosphere, it contributes to global warming, as methane and carbon dioxide are greenhouse gases

Answer 111

Ecosystem services such as mineral recycling and absorbing carbon dioxide on which the whole biosphere depends

Answer 112

have been polluted with acid, oil , plastic and sewage effluences.

Answer 113

are altering as the temperatures rises and species including herbaceous plants grow where in the past, only lichens and mosses were seen

Answer 114

biodiversity hot spots with up to 100 species per mm2 coral reef bleaching continues to cause species loss, as warm temps cause the zooxanthellae that gives the corals their colour to leave Their photosynthesis feeds the corals In many cases, they do not return, even if conditions improve and so the corals die Coastal communities are biodiverse. Mangroves, salt marshes and seagrass meadows absorb carbon dioxide up to 50 times more efficiently than the same area of tropical forest.

Answer 115

represents the misuse of land that results in too little food being produced In 2010, the crossing of that boundary was predicted for 2050, but 2015 data suggested that it had already been crossed

Answer 116

farming should be concentrated into the most productive areas. A global reduction in meat consumption would reduce the land under cultivation, and there is a significant role for genetically modified plants. Using land for food, however, conflicts with using it for biofuel production

Answer 117

Biogeochemical flows refer to the cycling minerals through the biotic and abiotic components of an ecosystem. Cycles have been described or many elements, such as carbon, sulphur,phosphorus and nitrogen. Mineral cycles are essential in maintaining availability of elements in the ions that transmitted throughout a food web.

Answer 118

so intensively that the boundries for both the nitrogen and phosphourouscycles have been used. Means that human activity has so disrupted these cycles that they are no longer self - sustaining. Polluting events that result from this, such as eutrophication, and further damaging ecosystems.

Answer 119

an aim for many years has been to transfer nitrogen fixing genes to crop plants but this has so far not been possible

Answer 120

Halogenated hydrocarbons, such s the chlorofluorocarbons ( CFC) 's alter the position of the equilibrium and favour the breakdown of ozone. Under the influence of ultraviolet light CFCs release chlorine as free radicals and each one can break down 100,00 ozone molecules

Answer 121

widely used as propellants in spray cans, solvents, refrigerator coolants and in the manafacture of disposable food and drink containers. Their molecules are heavier than air but within 2-5 years climb to the stratosphere. Depletion of stratospheric ozone was first observed in the 1970s, when the concentration of atmospheric CFCs reached a tipping point.

Answer 122

around the plant degraded but the thinning was so significant over Antarctica, that a hole in the layer was detected each spring. Ozone absorbs UVB, i.e ultraviolet radiation with a wavelength 280-315 nm and so the intensity of ultraviolet light at the planet surface increased

Answer 123

the range of wavelengths is strongly absorbed by DNA

Answer 124

1978 Montreal protocol agreed in 1987, banned the manufacture of CFCS and placed obligations on nation states to reduce their CFC use.

Answer 125

In the 17th century, the pH of the oceans was 8.16. Now it is 8.03. but the pH scale is logarithmic, it represents a 30% increase in the concentration of hydrogen ions. Carbon dioxide from the air dissolves in bodies of water as hydrogen carbonate releasing a hydrogen ion Hydrogen carbonate ios break down to carbonate ions and hydrogen ions. The increase in hydrogen ion concentration decreases the pH

Answer 126

H2O + CO2 --- H2CO3--- H+ + HCO3- HCO3- ------ H+ + CO32-

Answer 127

leaches calcium carbonate out of mollusc and coral shells and arthropod exoskeletons, softening them so organisms are vulnerable to physical and chemical attacks

Answer 128

CaCO3+H+ ---- Ca2+ + HCO3-

Answer 129

particularly vulnerable to low pH and their gill structure and functioning is damaged. Fish farms may have to consider changing species or relocating to more suitable waters, if the problem is not addressed.

Answer 130

liquid water is critical for the survival of living organisms. Many organisms, including the great majority of higher plants and most mammals, must have access to fresh water to live.

Answer 131

fresh water has a low concentration of dissolved salts, i.e less than 0.05 % sometimes called sweet water, to contrast it with sea water, which is salty

Answer 132

on the earth's surface, in ice sheets, ice caps, glaciers, icebergs,bogs,ponds, lakes, rivers and streams and underground as groundwater in aquifers and streams. Comes largely from precipitation as mist, rain and snow

Answer 133

it carries materials blown by the wind In industrialised areas, it may be acidic, in coastal areas it may contain salts, in desert or dusty soils, it may contain sand and dust, e.g rain falling in brazil sometimes contains iron, blown from sandstorms in the sahara

Answer 134

changing landscapes agriculture consumes more freshwater than any other human activity Increased demand as people move to warm climates, which have low levels of fresh water water pollution, e.g eutrophication makes water unsuitable to use. climate change increase in population through increasing life expectancy Increase in use, e.g when a person in the USA has a shower, they use, on average, more water than a person in a developing country would use in a whole day.

Answer 135

as glaciers melt in increasing global temperature, fresh availability initially increases, but there may be flooding. Then the availability decreases, causes drought The thermal expansion of ocean water rises sea levels, contaminating fresh water coastal regions. Ground water becomes too salty drinking and irrigation Semi - arid and arid areas are vulnerable because the rain, which is their water supply, occurs over a short space of time and evidence shows that these periods are apply disrupted

Answer 136

several methods for increasing the availability of fresh water: water conservation, e.g it has been suggested that non-food crops, such as biofuels and cotton should not be irrigated. Water efficiency Wastewater reclamation, for irrigation and industrial use Urban runoff and stormwater capture, recharging groundwater Drip irrigation systems successfully reduce the water volume used for irrigation of food crops. Because water containing fertilizer is dripped directly to the roots of the individual plants, rather than being sprayed over a large area

Answer 137

the removal of minerals from saline water

Answer 138

a technology that removes minerals from salt water, producing fresh water and leaving salt and recycled wastewater. it is one of the few sources of water that does not depend on the rain. Process can have a high energy consumption so water produced may be expensive.

Answer 139

Solar stills distill seawater using heat from the sun They convert saltwater entirely into distilled water and do not produce air pollution or warm water discharges that endanger local lakes or river

Answer 140

where seawater is separated from freshwater by a fine, selectively permeable membrane. Moves from the seawater, across the membrane to the fresh water, against its water potential gradient. Why the system requires energy

Answer 141

brine ( concentrated sodium chloride solution ) is discharged: the potential environmental impact of such a high salt concentration is avoided by diluting the brine before returning it to the ocean Brine is denser than seawater because of its high solute concentration. It sinks ad damages the seabed ecosystem Burning of fossil fuels to generate heat to run the system.

Answer 142

microscopic particles put into the atmosphere by combustion of fuels and by creating dust from digging and quarrying. Their concentration has doubled since before the industrial revolution/

Answer 143

exacerberate respiratory problems, causing deaths from lung disease. Deposition on leaves reduces light absorption for photosynthesis, providing some cooling effect, but other particulates e.g soot

Answer 144

previously called the chemical population boundary Name change reflects the increasing use of new technologies and materials. Encompasses organic pollutants, radioactive materials, nanomaterials and microplastics. Some chemicals are so toxic, their use has been widely restricted e.g DDT and PCBs.