Comparison of Greenshields, Pipes,and Van Aerde car-following and traffic stream models 2002 TRR
2024年高二英语植物保护的经济影响分析单选题30题
2024年高二英语植物保护的经济影响分析单选题30题1.The better plant protection can lead to ______ agricultural production.A.increasedB.reducedC.stableD.fluctuating答案：A。
本题考查形容词辨析。
更好的植物保护会带来农业产量的增加，increased 表示增加的；reduced 表示减少的；stable 表示稳定的；fluctuating 表示波动的。
根据题意，答案是increased。
2.Plant protection measures can help maintain ______ prices of agricultural products.A.highB.lowC.stableD.fluctuating答案：C。
本题考查形容词辨析。
植物保护措施能帮助维持农产品价格稳定，stable 表示稳定的；high 表示高的；low 表示低的；fluctuating 表示波动的。
所以答案是stable。
3.Without proper plant protection, the output of agricultural products may ______.A.increaseB.decreaseC.remain unchangedD.fluctuate randomly答案：B。
本题考查动词辨析。
没有适当的植物保护，农产品的产量可能会减少，decrease 表示减少；increase 表示增加；remain unchanged 表示保持不变；fluctuate randomly 表示随机波动。
故答案是decrease。
4.Plant protection is crucial for ensuring a stable ______ of agricultural products.A.supplyB.demandC.priceD.quality答案：A。
3生态环保类高考真题阅读
专题三生态环保类2019年Passage 1 2019北京，8分话题：微生物对海洋颜色的影响词数：386 By the end of the century, if not sooner, the world’s oceans will be bluer and greener thanks to a warming climate, according to a new study.At the heart of the phenomenon lie tiny marine microorganisms(海洋微生物) called phytoplankton. Because of the way light reflects off the organisms, these phytoplankton create colourful patterns at the ocean surface. Ocean colour varies from green to blue, depending on the type and concentration of phytoplankton. Climate change will fuel the growth of phytoplankton in some areas, while reducing it in other spots, leading to changes in the ocean’s appearance.Phytoplankton live at the ocean surface, where they pull carbon dioxide(二氧化碳) into the ocean while giving off oxygen. When these organisms die, they bury carbon in the deep ocean, an important process that helps to regulate the global climate. But phytoplankton are vulnerable to the ocean’s warming trend. Warming changes key characteristics of the ocean and can affect phytoplankton growth, since they need not only sunlight and carbon dioxide to grow, but also nutrients.Stephanie Dutkiewicz, a scientist in MIT’s Center for Global Change Science, built a climate model that projects changes to the oceans throughout the century. In a world that warms up by 3℃, it found that multiple changes to the colour of the oceans would occur. The model projects that currently blue areas with little phytoplankton could become even bluer. But in some waters, such as those of the Arctic, a warming will make conditions riper for phytoplankton, and these areas will turn greener. “Not only are the quantities of phytoplankton in the ocean changing. ” she said, “but the type of phytoplankton is changing.”And why does that matter? Phytoplankton are the base of the food web. If certain kinds begin to disappear from the ocean, Dutkiewicz said, “it will change the type of fish that will be able to survive.” Those kinds of changes could affect the food chain.Whatever colour changes the ocean experiences in the coming decades will probably be too gradual and unnoticeable, but they could mean significant changes. “It’ll be a while before we can statistically show that the changes are happening because of climate change,” Dutkiewicz said, “but the change in the colour of the ocean will be one of the early warning signals that we really have changed our planet.”42. What are the first two paragraphs mainly about?A. The various patterns at the ocean surface.B. The cause of the changes in ocean colour.C. The way light reflects off marine organisms.D. The efforts to fuel the growth of phytoplankton.43. What does the underlined word “vulnerable” in Paragraph 3 probably mean?A. Sensitive.B. BeneficialC. Significant.D. Unnoticeable.44. What can we learn from the passage?A. Phytoplankton play a declining role in the marine ecosystem.B. Dutkiewicz’s model aims to project phytoplankton changes.C. Phytoplankton have been used to control global climate.D Oceans with more phytoplankton may appear greener.45. What is the main purpose of the passage?A. To assess the consequences of ocean colour changes.B. To analyse the composition of the ocean food chain.C To explain the effects of climate change on oceans.D. To introduce a new method to study phytoplankton.Passage 2 2019浙江，10分话题：加州大树急剧减少词数：298California has lost half its big trees since the 1930s, according to a study to be published Tuesday and climate change seems to be a major factor(因素).The number of trees larger than two feet across has declined by 50 percent on more than 46, 000 square miles of California forests, the new study finds. No area was spared or unaffected, from the foggy northern coast to the Sierra Nevada Mountains to the San Gabriels above Los Angeles. In the Sierra high country, the number of big trees has fallen by more than 55 percent; in parts of southern California the decline was nearly 75 percent.Many factors contributed to the decline, said Patrick McIntyre, an ecologist who was the lead author of the study. Woodcutters targeted big trees. Housing development pushed into the woods. Aggressive wildfire control has left California forests crowded with small trees that compete with big trees for resources(资源).But in comparing a study of California forests done in the 1920s and 1930s with another one between 2001 and 2010, McIntyre and his colleagues documented a widespread death of big trees that was evident even in wildlands protected from woodcutting or development.The loss of big trees was greatest in areas where trees had suffered the greatest water shortage. The researchers figured out water stress with a computer model that calculated how much water trees were getting in comparison with how much they needed, taking into account such things as rainfall, air temperature, dampness of soil, and the timing of snowmelt(融雪).Since the 1930s, McIntyre said, the biggest factors driving up water stress in the state have been rising temperatures, which cause trees to lose more water to the air, and earlier snowmelt, which reduces the water supply available to trees during the dry season.27 What is the second paragraph mainly about?A. The seriousness of big -tree loss in California.B. The increasing variety of California big trees.C. The distribution of big trees in California forests.D. The influence of farming on big trees in California.28. Which of the following is well -intentioned but may be bad for big trees?A. Ecological studies of forests.B. Banning woodcutting.C. Limiting housing development.D. Fire control measures.29. What is a major cause of the water shortage according to McIntyre?A. Inadequate snowmelt.B. A longer dry season.C. A warmer climate.D. Dampness of the air.30. What can be a suitable title for the text?A. California’s Forests: Where Have All the Big Trees Gone?B. Cutting of Big Trees to Be Prohibited in California SoonC. Why Are the Big Trees Important to California Forests?D. Patrick McIntyre: Grow More Big Trees in CaliforniaPassage 3 2019天津，12.5分 话题：生态系统与食物网 词数：355How does an ecosystem (生态系统) work ? What makes the populations of different species the way they are ? Why are there so many flies and so few wolves ? To find an answer , scientists have built mathematical models of food webs , noting who eats whom and how much each one eats.With such models scientists have found out some key principles operating in food webs. Most food webs , for instance , consist of many weak links rather than a few strong ones. When a predator (掠食动物) always eats huge numbers of a single prey (猎物), the two species are strongly linked; when a predator lives on various species , they are weakly linked. Food webs may be dominated by many weak links because that arrangement is more stable over the long term. If a predator can eat several species , it can survive the extinction (灭绝) of one of them. And if a .,predator can move on to another species that is easier to find when a prey species becomes rare, the switch allows the original prey to recover. The weak links may thus keep species from driving one another to extinction.Mathematical models have also revealed that food webs may be unstable, where small changes of top predators can lead to big effects throughout entire ecosystems. In the 1960s, scientists proposed that predators at the top of a food web had a surprising amount of control over the size of populations of other species—including species they did not directly attack.And unplanned human activities have proved the idea of top-down control by top predators to be true. In the ocean, we fished for top predators such as cod on an industrial scale, while on land, we killed off large predators such as wolves. These actions have greatly affected the ecological balance.Scientists have built an early-warning system based on mathematical models. Ideally, the system would tell us when to adapt human activities that are pushing an ecosystem toward a breakdown or would even allow us to pull an ecosystem back from the borderline. Prevention is key, scientists say, because once ecosystems pass their tipping point(临界点), it is remarkably difficult for them to return.46. What have scientists discovered with the help of mathematical models of food webs?A. The living habits of species in food webs.B. The rules governing food webs of the ecosystems.C. The approaches to studying the species in the ecosystems.D. The differences between weak and strong links in food webs.47. A strong link is found between two species when a predator ________.A. has a wide food choiceB. can easily find new preyC. sticks to one prey speciesD. can quickly move to another place48. What will happen if the populations of top predators in a food web greatly decline?A. The prey species they directly attack will die out.B. The species they indirectly attack will turn into top predators.C. The living environment of other species will remain unchanged.D. The populations of other species will experience unexpected changes.49. What conclusion can be drawn from the examples in Paragraph 4?A. Uncontrolled human activities greatly upset ecosystems.B. Rapid economic development threatens animal habitats.C. Species of commercial value dominate other species.D. Industrial activities help keep food webs stable.50. How does an early-warning system help us maintain the ecological balance?A. By getting illegal practices under control.B. By stopping us from killing large predators.C. By bringing the broken-down ecosystems back to normal.D. By signaling the urgent need for taking preventive action.2018年Passage 1 2018全国I，8分话题：过时电子设备耗能高词数：349We may think we’re a culture that gets rid of our worn technology at the first sight of something shiny and new, but a new study shows that we keep using our old devices(装置) well after they go out of style. That’s bad news for the environment — and our wallets — as these outdated devices consume much more energy than the newer ones that do the same things.To figure out how much power these devices are using, Callie Babbitt and her colleagues at the Rochester Institute of Technology in New York tracked the environmental costs for each product throughout its life — from when its minerals are mined to when we stop using the device.This method provided a readout for how home energy use has evolved since the early 1990s. Devices were grouped by generation. Desktop computers, basic mobile phones, and box-set TVs defined 1992. Digital cameras arrived on the scene in 1997. And MP3 players, smart phones, and LCD TVs entered homes in 2002, before tablets and e-readers showed up in 2007.As we accumulated more devices, however, we didn’t throw out our old ones. "The living-room television is replaced and gets planted in the kids’room, and suddenly one day, you have a TV in every room of the house," said one researcher. The average number of electronic devices rose from four per household in 1992 to 13 in 2007. We’re not just keeping these old devices — we continue to use them. According to the analysis of Babbitt’s team, old desktop monitors and box TVs with cathode ray tubes are the worst devices with their energy consumption and contribution to greenhouse gas emissions(排放）more than doubling during the 1992 to 2007 window.So what’s the solution(解决方案)? The team’s data only went up to 2007, but the researchers also explored what would happen if consumers replaced old products with new electronics that serve more than one function, such as a tablet for word processing and TV viewing. They found that more on-demand entertainment viewing on tablets instead of TVs and desktop computers could cut energy consumption by 44%.1.What does the author think of new devices?A. They are environment-friendly.B. They are no better than the old.C. They cost more to use at home.D. They go out of style quickly.2.Why did Babbitt’s team conduct the research?A. To reduce the cost of minerals.B. To test the life cycle of a product.C. To update consumers on new technology.D. To find out electricity consumption of the devices.3.Which of the following uses the least energy?A. The box-set TV.B. The tablet.C. The LCD TV.D. The desktop computer.4.What does the text suggest people do about old electronic devices?A. Stop using them.B. Take them apart.C. Upgrade them.D. Recycle them.Passage 2 2018北京，8分话题：大蜡螟幼虫分解塑料垃圾词数：340Plastic-Eating WormsHumans produce more than 300 million tons of plastic every year. Almost half of that winds up in landfills (垃圾填埋场)，and up to 12 million tons pollute the oceans. So far there is no effective way to get rid of it, but a new study suggests an answer may lie in the stomachs of some hungry worms.Researchers in Spain and England recently found that the worms of the greater wax moth can break down polyethylene, which accounts for 40% of plastics. The team left 100 wax worms on a commercial polyethylene shopping bag for 12 hours，and the worms consumed and broke down about 92 milligrams, or almost 3% of it. To confirm that the worms’ chewing alone was not responsible for the polyethylene breakdown，the researchers made some worms into paste (糊状物)and applied it to plastic films.14 hours later the films had lost 13%of their mass — apparently broken down by enzymes (酶) from the worms’ stomachs.Their findings were published in Current Biology in 2017.Federica Bertocchini, co author of the study, says the worms’ ability to break down their everyday food — beeswax — also allows them to break down plastic."Wax is a complex mixture，but the basic bond in polyethylene，the carbon carbon bond，is there as well，"she explains. "The wax worm evolved a method or system to break this bond."Jennifer DeBruyn，a microbiologist at the University of Tennessee，who was not involvedin the study，says it is not surprising that such worms can break down polyethylene. But compared with previous studies，she finds the speed of breaking down in this one exciting. The next step，DeBruyn says，will be to identify the cause of the breakdown. Is it an enzyme produced by the worm itself or by its gut microbes(肠道微生物)？Bertocchini agrees and hopes her team’s findings might one day help employ the enzyme to break down plastics in landfills. But she expects using the chemical in some kind of industrial process — not simply "millions of worms thrown on top of the plastic."1.What can we learn about the worms in the study?A. They take plastics as their everyday food.B. They are newly evolved creatures.C. They can consume plastics.D. They wind up in landfills.2.According to Jennifer DeBruyn, the next step of the study is to .A. identify other means of the breakdownB. find out the source of the enzymeC. confirm the research findingsD. increase the breakdown speed3.It can be inferred from the last paragraph that the chemical might .A. help to raise wormsB. help make plastic bagsC. be used to clean the oceansD. be produced in factories in future4.What is the main purpose of the passage？A. To explain a study method on worms.B. To introduce the diet of a special worm.C. To present a way to break down plastics.D. To propose new means to keep eco-balance.2017年Passage 1 2017全国卷Ⅰ，8分话题：野生动物保护词数：289I work with Volunteers for Wildlife, a rescue and education organization at Bailey Arboretum in Locust Valley. Trying to help injured, displaced or sick creatures can be heartbreaking; survival is never certain.However, when it works, it is simply beautiful.I got a rescue call from a woman in Muttontown. She had found a young owl(猫头鹰) on the ground. When I arrived, I saw a 2- to 3-week-old owl. It had already been placed in a carrier for safety.I examined the chick(雏鸟)and it seemed fine. If I could locate the nest, I might have been able to put it back, but no luck. My next work was to construct a nest and anchor it in a tree.The homeowner was very helpful. A wire basket was found. I put some pine branches into the basket to make this nest safe and comfortable. I placed the chick in the nest, and it quickly calmed down.Now all that was needed were the parents, but they were absent. I gave the homeowner a recording of the hunger screams of owl chicks. These advertise the presence of chicks to adults; they might also encourage our chick to start calling as well. I gave the owner as much information as possible and headed home to see what news the night might bring.A nervous night to be sure, but sometimes the spirits of nature smile on us all! The homeowner called to say that the parents had responded to the recordings. I drove over and saw the chick in the nest looking healthy and active. And it was accompanied in the nest by the greatest sight of all —LUNCH! The parents had done their duty and would probably continue to do so.1.What is unavoidable in the author’s rescue work according to paragraph 1?A. Efforts made in vain.B. Getting injured in his work.C. Feeling uncertain about his future.D. Creatures forced out of their homes.2. Why was the author called to Muttontown?A. To rescue a woman.B. To take care of a woman.C. To look at a baby owl.D. To cure a young owl.3. What made the chick calm down?A. A new nest.B. Some food.C. A recording.D. Its parents.4. How would the author feel about the outcome of the event?A. It’s unexpected.B. It’s beautiful.C. It’s humorous.D. It’s discouraging. Passage 2 2017全国卷Ⅲ，8分话题：生态平衡词数：288After years of heated debate, gray wolves were reintroduced to Yellowstone National Park. Fourteen wolves were caught in Canada and transported to the park. By last year, the Yellowstone wolf population had grown to more than 170 wolves.Gray wolves once were seen here and there in the Yellowstone area and much of the continental United States, but they were gradually displaced by human development. By the 1920s, wolves had practically disappeared from the Yellowstone area. They went farther north into the deep forests of Canada, where there were fewer humans around.The disappearance of the wolves had many unexpected results. Deer and elk populations —major food sources (来源) for the wolf —grew rapidly. These animals consumed large amounts of vegetation (植被)，which reduced plant diversity in the park. In the absence of wolves, coyote populations also grew quickly. The coyotes killed a large percentage of the park’s red foxes, and completely drove away the park’s beavers.As early as 1966, biologists asked the government to consider reintroducing wolves to Yellowstone Park. They hoped that wolves would be able to control the elk and coyote problems. Many farmers opposed the plan because they feared that wolves would kill their farm animals or pets.The government spent nearly 30 years coming up with a plan to reintroduce the wolves. The U.S. Fish and Wildlife Service carefully monitors and manages the wolf packs in Yellowstone. Today, the debate continues over how well the gray wolf is fitting in at Yellowstone. Elk, deer, and coyote populations are down, while beavers and red foxes have made a comeback. The Yellowstone wolf project has been a valuable experiment to help biologists decide whether to reintroduce wolves to other parts of the country as well.1.What is the text mainly about?A. Wildlife research in the United States.B. Plant diversity in the Yellowstone area.C. The conflict between farmers and gray wolves.D. The reintroduction of wolves to Yellowstone Park.2.What does the underlined word "displaced" in paragraph 2 mean?A. Tested.B. Separated.C. Forced out.D. Tracked down.3.What did the disappearance of gray wolves bring about?A. Damage to local ecology.B. A decline in the park’s income.C. Preservation of vegetation.D. An increase in the variety of animals.4.What is the author’s attitude towards the Yellowstone wolf project?A. Doubtful.B. Positive.C. Disapproving.D. Uncaring.2012—2016年Passage 1 2016北京，8分词数：357California Condor's Shocking RecoveryCalifornia condors are North America's largest birds, with wing-length of up to 3 meters. In the 1980s, electrical lines and lead poisoning(铅中毒) nearly drove them to dying out. Now, electric shock training and medical treatment are helping to rescue these bigbirds.In the late 1980s, the last few condors were taken from the wild to be bred(繁殖). Since 1992, there have been multiple reintroductions to the wild, and there are now more than 150 flying over California and nearby Arizona, Utah and Baja in Mexico.Electrical lines have been killing them off. "As they go in to rest for the night, they just don't see the power lines," says Bruce Rideout of San Diego Zoo. Their wings can bridge the gapbetween lines, resulting in electrocution(电死) if they touch two lines at once.So scientists have come up with a shocking idea. Tall poles, placed in large training areas, teach the birds to stay clear of electrical lines by giving them a painful but undeadly electric shock. Before the training was introduced, 66% of set-free birds died of electrocution. This has now dropped to 18%.Lead poisoning has proved more difficult to deal with. When condors eat dead bodies of other animals containing lead, they absorb large quantities of lead. This affects their nervous systems and ability to produce baby birds, and can lead to kidney(肾) failure and death. So condors with high levels of lead are sent to Los Angeles Zoo, where they are treated with calcium EDTA, a chemical that removes lead from the blood over several days. This work is starting to pay off. The annual death rate for adult condors has dropped from 38% in 2000 to 5.4% in 2011.Rideout's team thinks that the California condors' average survival time in the wild is now just under eight years. "Although these measures are not effective forever, they are vital for now," he says. "They are truly good birds that are worth every effort we put into recovering them."1.California condors attract researchers' interest because they ____.A. are active at nightB. had to be bred in the wildC. are found only in CaliforniaD. almost died out in the 1980s2.Researchers have found electrical lines are ____.A. blocking condors' journey homeB. big killers of California condorsC. rest places for condors at nightD. used to keep condors away3.According to Paragraph 5, lead poisoning ____.A. makes condors too nervous to flyB. has little effect on condors' kidneysC. can hardly be gotten rid of from condors' bloodD. makes it difficult for condors to produce baby birds4.This passage shows that ____.A. the average survival time of condors is satisfactoryB. Rideout's research interest lies in electric engineeringC. the efforts to protect condors have brought good resultsD. researchers have found the final answers to the problemPassage 2 2016江苏，8分词数：437El Niño, a Spanish term for "the Christ child," was named by South American fishermen who noticed that the global weather pattern, which happens every two to seven years, reduced the amount of fishes caught around Christmas. El Niño sees warm water, collected over several years in the western Pacific, flow back eastwards when winds that normally blow westwards weaken, or sometimes the other way round.The weather effects, both good and bad, are felt in many places. Rich countries gain more from powerful Niños, on balance, than they lose. A study found that a strong Niño in 1997-98 helped America's economy grow by $15 billion, partly because of better agricultural harvests: farmers in the Midwest gained from extra rain. The total rise in agricultural incomes in rich countries is greater than the fall in poor ones.But in Indonesia extremely dry forests are in flames. A multi-year drought (干旱) in south-east Brazil is becoming worse. Though heavy rains brought about by El Niño may relieve the drought in California, they are likely to cause surface flooding and other disasters.The most recent powerful Niño, in 1997-98, killed around 21,000 people and caused damage worth $36 billion around the globe. But such Niños come with months of warning, and so much is known about how they happen that governments can prepare. According to the Overseas Development Institute (ODI), however, just 12% of disaster-relief funding in the past two decades has gone on reducing risks in advance, rather than recovery and rebuilding afterwards. This isdespite evidence that a dollar spent on risk-reduction saves at least two on reconstruction.Simple improvements to infrastructure (基础设施) can reduce the spread of disease. Better sewers (下水道) make it less likely that heavy rain is followed by an outbreak of the disease of bad stomach. Stronger bridges mean villages are less likely to be left without food and medicine after floods. According to a paper in 2011 by Mr Hsiang and co-authors, civil conflict is related to El Niño's harmful effects — and the poorer the country, the stronger the link. Though the relationship may not be causal, helping divided communities to prepare for disasters would at least reduce the risk that those disasters are followed by killing and wounding people. Since the poorest are least likely to make up for their losses from disasters linked to El Niño, reducing their losses needs to be the priority.1.What can we learn about El Niño in Paragraph 1?A. It is named after a South American fisherman.B. It takes place almost every year all over the world.C. It forces fishermen to stop catching fish around Christmas.D. It sees the changes of water flow direction in the ocean.2.What may El Niños bring about to the countries affected?A. Agricultural harvests in rich countries fall.B. Droughts become more harmful than floods.C. Rich countries' gains are greater than their losses.D. Poor countries suffer less from droughts economically.3.The data provided by ODI in Paragraph 4 suggest that ____.A. more investment should go to risk reductionB. governments of poor countries need more aidC. victims of El Niño deserve more compensationD. recovery and reconstruction should come first4.What is the author's purpose in writing the passage?A. To introduce El Niño and its origin.B. To explain the consequences of El Niño.C. To show ways of fighting against El Niño.D. To urge people to prepare for El Niño. Passage 3 2015浙江,10分词数:492If humans were truly at home under the light of the moon and stars, we would go in darkness happily, the midnight world as visible to us as it is to the vast number of nocturnal (夜间活动的) species on this planet. Instead, we are diurnal creatures, with eyes adapted to living in the sun's light. This is a basic evolutionary fact, even though most of us don't think of ourselves as diurnal beings. Yet it's the only way to explain what we've done to the night: We've engineered it to receive us by filling it with light.The benefits of this kind of engineering come with consequences — called light pollution — whose effects scientists are only now beginning to study. Light pollution is largely the result of bad lighting design, which allows artificial light to shine outward and upward into the sky. Ill-designed lighting washes out the darkness of night and completely changes the light levels — and light rhythms — to which many forms of life, including ourselves, have adapted. Wherever human light spills into the natural world, some aspect of life is affected.In most cities the sky looks as though it has been emptied of stars, leaving behind a vacant haze (霾) that mirrors our fear of the dark. We've grown so used to this orange haze that the original glory of an unlit night — dark enough for the planet Venus to throw shadows on Earth — is wholly beyond our experience, beyond memory almost.We've lit up the night as if it were an unoccupied country, when nothing could be further from the truth. Among mammals alone, the number of nocturnal species is astonishing. Light is a powerful biological force, and on many species it acts as a magnet (磁铁). The effect is so powerful that scientists speak of songbirds and seabirds being "captured" by searchlights on land。
小学上册第13次英语第三单元测验卷(含答案)
小学上册英语第三单元测验卷(含答案)英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1.What is the term for a baby chicken?A. DucklingB. ChickC. GoslingD. Calf答案:B.Chick2.What is the color of the grass?A. BlueB. GreenC. YellowD. Red答案: B3.What is the opposite of "happy"?A. JoyfulB. SadC. AngryD. Excited答案: B4.The _______ of sound can be perceived in different ways depending on the environment.5.It is ________ (sunny) today.6. A _____ (小狼) howls at the moon.7.The ____ is a favorite among children and loves to play in the grass.8.This ________ (玩具) helps me think critically.9.The _____ (raspberry) plant produces sweet berries.10.The _____ (兔子) has long ears and a short tail.11.An endothermic process absorbs ______.12.The process of photosynthesis is crucial for ______.13.The chemical symbol for uranium is ______.14.The sun sets in the ______ (west).15.Heat can speed up a ______.16. A dolphin's intelligence is fascinating to ______ (科学家).17.The Great Smoky Mountains are located on the border of _______ and North Carolina.18.What do you call the act of making a choice?A. DecidingB. ChoosingC. SelectingD. Picking答案: A19.I love _______ (和家人一起)去旅行。
Changes in the soil environment from excessive application
Changes in the soil environment from excessive application of fertilizers and manures to two contrasting intensivecropping systems on the North China PlainX.T.Ju a ,*,C.L.Kou a ,b ,P.Christie a ,c ,Z.X.Dou d ,F.S.Zhang aaKey Laboratory of Plant e Soil Interactions,Ministry of Education;College of Agricultural Resources and Environmental Sciences,China Agricultural University,Beijing 100094,ChinabInstitute of Soil and Fertilization,Henan Academy of Agricultural Sciences,Zhengzhou,450002,ChinacAgricultural and Environmental Science Department,Queen’s University Belfast,Newforge Lane,Belfast BT95PX,UKdCenter for Animal Health and Productivity,Department of Clinical Studies,School of Veterinary Medicine,University of Pennsylvania,382West Street Road,Kennett Square,PA 19348,USAReceived 2December 2005;received in revised form 19April 2006;accepted 20April 2006Extremely high nutrient inputs to intensively managed vegetable crops in northeast China may leadto very serious degradation of soil and water quality.AbstractEffects of excessive fertilizer and manure applications on the soil environment were compared in greenhouse vegetable systems shifted from wheat e maize rotations 5e 15years previously and in wheat e maize rotations.N,P and K surpluses to the greenhouses were 4328,1337and 1466kg ha À1year À1,respectively compared to 346,65and À163kg ha À1year À1to wheat e maize fields.Subsequently,substantial mineral N and available P and K accumulated in the soil and leaching occurred down the soil profile in the greenhouses.Soil pH under vegetables was sig-nificantly lower than in the wheat e maize fields,while the EC was significantly higher in the vegetable soils.The mean Cd concentration in the vegetable soils was 2.8times that in the wheat e maize rotations.Due to excessive fertilizer application in greenhouse vegetable production in north-east China,excessive salt and nitrate concentrations may accumulate and soil quality may deteriorate faster than in conventional wheat e maize rotations.Ó2006Elsevier Ltd.All rights reserved.Keywords:Greenhouse vegetables;Wheat e maize rotation;Nitrogen;Phosphorus;Potassium;Electrical conductivity;Soil pH;Trace elements;Heavy metals1.IntroductionMineral fertilizer consumption in Chinese agriculture has increased greatly over the last three decades but has decreased in northwest Europe over the same period (Richter and Roelcke,2000;Ju et al.,2004a ).At present,overuse or misuse of fertilizers in agriculture in northeast China contributes toenvironmental damage from non-point source pollution (Zhang et al.,2004;Jin et al.,2005)and is therefore of great concern nationally and internationally.Fertilizer application rates in intensive agricultural systems have increased dramat-ically in recent years on the North China Plain,especially in greenhouse vegetable production systems (Ju et al.,2005).Because of the relatively high economic value of the extra yields and difficulties in the accurate management of water and nutrient supply in these systems,farmers use very large amounts of fertilizers and irrigation water to obtain maximum yields.For example,fertilizer N is often applied at rates*Corresponding author.Tel.:þ861062733459;fax:þ861062731016.E-mail address:juxt@ (X.T.Ju).0269-7491/$-see front matter Ó2006Elsevier Ltd.All rights reserved.doi:10.1016/j.envpol.2006.04.017Environmental Pollution 145(2007)497e506/locate/envpol>1200kg N haÀ1and irrigation water at1000mm per crop, and two or three crops are grown each year in one of the most important vegetable production areas,Shouguang,Shan-dong province(Zhu et al.,2005).These high fertilizer inputs and the extremely low crop recoveries of fertilizer nutrients (usually<10%in the case of N)lead to marked deterioration in soil and groundwater quality and the systems are clearly un-sustainable(Zhang et al.,1996;Li et al.,2001;Dou,2005; Zhu et al.,2005).Although similar problems were faced from the1960s to the1980s in western European countries(Richter and Roelcke,2000;Van Eerdt et al.,2005),their magnitude was lower than the current Chinese problem.For instance,an ap-plication rate of fertilizer N of200kg haÀ1for one cereal crop would have been regarded as high in western Europe but the rate currently used by most farmers in northeast China exceeds300kg N haÀ1per crop and there may be two or three crops in one year.In vegetable production systems the fertil-izer N application rate in western Europe would have seldom matched the rate of2800kg N haÀ1used in greenhouse sys-tems by some farmers in northeast China(Ju et al.,2004a). Chinese greenhouse vegetable production systems thus pro-vide an excellent opportunity for studying the effects of ex-tremely high fertilizer inputs on degradation of soil and water quality.Soil quality can be defined as the capacity of the soil to function within ecosystem and land use boundaries,to sustain biological productivity,maintain environmental quality and promote plant,animal and human health(Doran et al., 1996).Soil chemical and biological properties in greenhouse vegetable production may change dramatically after several years of continually high inputs of fertilizers and irrigation wa-ter and planting of shallow rooting vegetable crops compared with openfield cereal production systems.Soil OM,alkali-hydrolyzable N,and available P and K have been observed to accumulate significantly in vegetable greenhouses(Gao et al.,2000).Because farmers prefer to apply high-P fertilizers such as diammonium phosphate or15e15e15compound fertilizers to vegetable crops in north China,high concentra-tions of P and imbalances of N,P and K often occur in the intensively managed soils.Changes in soil water balance resulting from a lack of leaching by rainfall and strong evaporation of soil water due to long-term cover together with high fertilizer application rates may lead to increasing salinity in the surface soils of the plasticfilm greenhouses in which vegetables are grown (Wu et al.,2000).The main anion present is NO3À(67e76% of total anions)in soil salinity in these systems(Xue et al., 1994)and NO3Àcontent was found to be significantly corre-lated with total soil salinity(Liang et al.,1997).Secondary sa-linization in the greenhouse soils is characterized by accumulation of NO3À,a contrasting situation compared with saline soils in openfields of coastal and inland areas.Soil sa-linization increases the osmotic potential of the soil solution, leading to water stress and ion antagonism in the crops(Green-way and Munns,1980).Total soil salinity content and NO3Àcontent showed significant correlations with soil EC(Xue et al.,1994).Thus,soil EC may be used as an index of salt ac-cumulation or NO3Àaccumulation under these conditions.The tolerance limit of most crops is an EC of0.4S mÀ1(Kingery et al.,1994).Some studies have shown soil EC values up to 0.4S mÀ1in greenhouses after8years of intensive vegetable cropping(Wu et al.,2000;Li et al.,2001).Long-term application of large amounts of fertilizers and manures may lead to soil acidification in vegetable green-houses.Numerous studies have shown decreasing soil pH with increasing number of cropping years(Meng et al., 2000;Zhao et al.,2000).After13years of greenhouse vegeta-ble production in Shouguang,Shandong province,the soil pH declined to4.3in some cases,with potential detrimental ef-fects on crop yield and quality in these systems(Li,2001). Changes in soil pH may affect nutrient availability,and in cal-careous soils a decrease in soil pH may increase the availabil-ity of elements such as P,Fe,Mn,Cu,and Zn,but extremely low soil pH values could have direct detrimental effects on plant growth.Exchangeable Ca and Mg in vegetable green-house soils were lower than in openfields,but available Cu, Fe,Mn,and Zn showed the opposite trend(Xiao et al.,1997).Few studies have examined heavy metals in vegetable greenhouse soils.Many phosphate rocks contain heavy metals such as Pb and Cd and large application rates of P fertilizer may not only increase soil P but also lead to accumulation of the metals above the maximum limit values(Sharpley and Menzel,1987;Song et al.,1996;Powlson,1997).Jinadasa et al.(1997)found that Cd concentrations in vegetables could exceed the limit value if the soil Cd concentration reached 0.3mg Cd kgÀ1.Clearly,systematic studies on the impacts of different crop-ping systems(i.e.different management practices)on soil properties are needed for the proper development of sustain-able high yielding vegetable systems in relation to environ-mental quality.The objectives of the present study were to investigate soil nutrients and heavy metal accumulation and changes in soil pH and EC in vegetable greenhouses and to compare these withfields used for cereal rotations.We took wheat e maizefields as a reference because the vegetable greenhouses were established on areas formerly used to grow wheat e maize rotations.This may allow comparison be-tween conditions on areas that changed to greenhouse vegeta-ble production with surrounding areas that have remained under wheat e maize rotations.2.Materials and methods2.1.Site description and cropping systemsThe study site at Huimin county is located on the north shore of the lower reaches of the Yellow River in the northeast of Shandong province on an allu-vial plain at37 60e37 360N,117 160e117 490E.There is an area offlat ag-ricultural land of73,480ha with a mean altitude of12.8m and a gradient of 1:6000at the ground surface.Annual average precipitation was578mm for the period1971to2000,of which61e84%occurred between June and Au-gust,and is typical of the warm-temperate sub-humid continental monsoon cli-mate.The main soil type is loamy silty alluvial soil(FAO system).The main crops grown are wheat,maize,greenhouse vegetables,cotton(Gossypium hir-sutum L.),and fruit trees.Zijiao township,one of the most important vegetable498X.T.Ju et al./Environmental Pollution145(2007)497e506production areas in the county,was selected as a representative area for investigation.One of the planting patterns in the greenhouse vegetable cropping system consisted of transplanting cucumber(Cucumis sativus L.)in October andfinal harvest in June of the following year,then a fallow period until October.An-other pattern was sowing of celery(Apium graveolens L.)in October andfinal harvest in January of the following year,then growing tomato(Lycopersicon esculentum Mill.)from February to July,and then a fallow period until Octo-ber.During this annual rotation,more than13irrigation events and seven split applications of fertilizer were applied in conventional farming practice.In the wheat e maize double cropping system winter wheat was grown from October to June of the following year and summer maize was grown from the middle of June to the end of September.Two applications of fertilizer,one basal appli-cation before sowing and one topdressing in the middle growth stages,were made to both crops combined with irrigation.2.2.Soil and manure samplingA multistage sampling technique was used to select representativefields for sampling soils from each cropping system.Firstly,we randomly selected three villages from a total of68villages in Zijiao township.Secondly,ten fields were randomly selected in each selected village for sampling soils from vegetable greenhouses.A total of30vegetable greenhouses were ran-domly selected in Zijiao township,and an adjacent wheat e maizefield was also selected to serve as a comparison with each greenhouse.The land had been used to grow wheat e maize rotations before the greenhouses were estab-lished5e15years before the study commenced.Soil samples were taken from all the selected greenhouses andfields over the period18e29June,2002and after the crops were harvested.Samples were collected from the top90cm of the soil profile atfive sites(following a serpentine pattern in eachfield)at30-cm intervals in each vegetable greenhouse and cerealfield.Samples from the five sites in eachfield were mixed thoroughly to obtain composite samples from each depth layer(0e30,30e60and60e90cm),placed in labeled plastic bags,sealed and stored in ice boxes before analysis for NH4þ-N and NO3À-N in the laboratory.The main types of organic manure used by local farmers are cattle,pig and chicken manures,hemp seed cake,bean cake and cottonseed cake.Samples of these manures were collected when farmers were applying them in thefield from October2001to September2002.Samples of about1kg were collected from10e15points within each manure heap.They were placed on clean plas-tic boards,broken up and mixed thoroughly and a sub-sample of about0.5kg was obtained using the quartering procedure.Part of this sub-sample was used to determine water content and the remainder was air-dried for nutrient analysis.2.3.Sample analysisFresh soil samples were divided into two sub-samples after sieving to <5mm,one of which was used to determine soil mineral nitrogen(NO3À-N and NH4þ-N)and the other was air-dried for analysis of soil pH,EC,OM, TN,available P and K,available Zn,Mn,Fe,Cu and the additional heavy metals Pb and Cd.Each fresh soil sub-sample was extracted with0.01mol LÀ1 CaCl2to determine the concentrations of NH4þ-N and NO3À-N using a contin-uousflow analyzer(TRAACS2000,Bran and Luebbe,Norderstedt,Germany). Soil OM was measured by dichromate digestion,TN by the Kjeldahl method, soil pH in water with a1:2.5soil-to-water ratio,soil EC by a1:5soil-to-water ratio as described by Rhoades(1996),available P(Olsen-P)by extraction with 0.5mol LÀ1NaHCO3,available K by extraction with1mol LÀ1NH4OAC, and microelements and heavy metals by the DTPA extraction-ICP method (Optima3300DV,Perkin Elmer,USA).Total N,P,and K in manure were measured according to the methods of Che and He(1999).2.4.Calculation of nutrient inputs and balanceDetailed records were made of farmers’management practices in each field from October2001to September2002and it was established that the management history of eachfield was similar to that practiced during the year of our survey.Background data collected included the area of thefield or greenhouse plot,the age of the greenhouse,and the types and amounts of fertilizers applied.N,P and K inputs from fertilizers were calculated from the amounts of fertilizers applied and the forms and concentrations of nutrients present.The main fertilizers used in the studyfields were urea,ammonium bi-carbonate,diammonium phosphate,compound or mixed fertilizers and cal-cium mono-phosphate.N,P and K inputs from organic manures were also estimated by analysis of representative samples and the application rates used.The nutrients remove by aboveground plant parts were calculated from nutrient concentrations and aboveground biomass.The nutrient balance was calculated by subtracting aboveground nutrient removal from fertilizer in-put(mineralþmanure).2.5.Statistical analysisThe primary data were manipulated using Microsoft Excel spreadsheets. The significance of fertilizers,soil nutrient accumulation,soil pH,EC,micro-nutrients and heavy metals comparing the two cropping systems were analyzed by t-test using the SAS software package(Version6.12,1997;SAS Institute Inc.,Cary,NC,USA).The regressions between soil pH,EC and NO3À-N con-centrations were analyzed using PROC NLIN of the SAS software package.3.Results3.1.Fertilizer and manure use and nutrient balance inthe two cropping systemsThe annual N,P and K inputs from fertilizers and manures applied to the greenhouse vegetable systems were all signifi-cantly(p<0.001)higher than those applied to the wheat-e maizefields(Table1).The rates of fertilizer N,P and K applied to greenhouse vegetables were 4.7,10.1and23.4 times those applied to the cerealfields,and the corresponding data for manure nutrients were33.0,26.7and15.2,respec-tively.The fertilizer inputs within each cropping system were very variable among individualfields,reflecting the lack of a formal fertilizer recommendation system and weak-ness of the local extension service.The annual fertilizer N,P and K inputs in the vegetable greenhouses were much higher than the application rates recommended by the extension service(N750e1030,P180e300,K225e375kg haÀ1)(He et al.,2000).As for the wheat e maize rotations,the annual fertilizer N rate was also much higher than recommended (N300e390kg haÀ1),but the annual fertilizer P rates were close to the range of recommended rates(P80e90kg haÀ1), and less K was applied than was recommended(K50e150kg haÀ1).Manures were applied to all of the greenhouses in our survey,but only to20of the30wheatfields during the wheat-growing season,and to none of the cerealfields during the maize growing season.The data indicate that most farm-yard manure is used for vegetable production.Moreover,K fertilizer was applied to27of the30greenhouses,but to only8of the30cerealfields surveyed for wheat,and to14fields for maize.Available K in the top30cm of the soil profile in the30wheat e maizefields was much lower than recommended as sufficient(>100mg kgÀ1,Fig.2B),which might result from crop residuals not having been returned to thefields in most cases.Very large surpluses of N,P and K were found in the green-house vegetable production system compared to the499X.T.Ju et al./Environmental Pollution145(2007)497e506wheat e maize rotation(Table2).The N removed by the above-ground parts of vegetables was not significantly(p>0.05) higher than by wheat e maize,but P and K were significantly higher(p<0.05).The N and P surpluses were also high but K was in deficit in the wheat e maize rotation.The K balance could be achieved by returning crop residues to thefields in the wheat e maize rotation because these would remove up to 210e223kg K haÀ1in our investigation.parison between the two cropping systems insoil OM,TN and mineral NSoil OM and TN in the greenhouses were significantly (27.6and38.1%,p<0.001)higher than in the wheat e maize fields(Table3),and this may be largely due to application of large amounts of manure for vegetable production.NO3À-N accumulation in the top90cm of greenhouse soils was significantly(p<0.001)higher than in wheat e maize fields(Fig.1A).The ranges were274e4219kg N haÀ1with 1390kg N haÀ1on average in the greenhouses,and 94e690kg N haÀ1with248kg N haÀ1on average in the wheat e maizefields.Although NH4þ-N accumulation in the top90cm of greenhouse soil profiles was significantly (p<0.01or0.001)higher than in cerealfields(Fig.1B), the difference between the two cropping systems was much smaller than the difference in NO3À-N.Average NH4þ-N accu-mulation at0e90cm soil depth in the greenhouses was 100.4kg N haÀ1compared with56.6kg N haÀ1in the cereal fields.Total soil accumulation of NO3À-N(0e90cm)amounted to 91%of soil mineral N in the greenhouses,and to79%in the cerealfields.This indicates that the soils had high potential for nitrification(Richter and Roelcke,2000;Liu et al.,2003;Ju et al.,2004a,b).Since NO3À-N was the main fraction of min-eral N,differences in mineral N(Nmin)between the two crop-ping systems showed similar trends to NO3À-N.Substantial accumulation of NO3À-N in the deep subsoil reflected strong leaching processes in both cropping systems,but especially in vegetable production.However,we did not determine soil exchangeable NH4þ-N and we have therefore underestimated the total amount of potentially available soil ammonium nitrogen.parison between the two cropping systems insoil available P and KSoil available P(0e90cm)in the greenhouses was signif-icantly(p<0.001)higher than in the wheat e maizefields (Fig.2A),being1321kg P haÀ1in the former and158kg P haÀ1in the latter,perhaps due to application of large amounts of P fertilizers in the greenhouses.The distribution of available P in the soil profile in two cropping systems showed similar trends and decreased with depth.Soil available P averaged over the30greenhouses(0e30cm)was above the local recommended sufficiency level(>150mg kgÀ1)and was at the moderate level(14e30mg kgÀ1)in the cerealfields.Soil available K(0e90cm)in the greenhouses was also significantly(p<0.001)higher than in the cerealfields (Fig.2B),with1817kg K haÀ1in the former and811kg K haÀ1in the latter.Soil available K in the greenhouses de-creased with increasing soil depth,but was similar throughout the soil profile in the cerealfields.Soil available K on average in the30greenhouses at0e30cm depth was at moderate level (150e200mg kgÀ1)and was much lower than the recommen-ded sufficiency level(>100mg kgÀ1)for wheat e maizefields. The substantial accumulation of P and K in the deep subsoilTable1Fertilizers and manures applied to two cropping systems in rotations in2001e02Cropping system No.ofsites DescriptiveStatisticsYield a(t haÀ1yearÀ1)Fertilizer(kg haÀ1yearÀ1)Manure(kg haÀ1yearÀ1)N P K N P KGreenhouse vegetables30Mean87.028239289251847481991Range7e171375e7344176e32520e265523e47754e138039e2794CV(%)50.6708283697567 Wheat e maize rotation30Mean11.36069238561865Range8.3e13.5240e109925e1540e1370e2460e800e286CV(%)12.4303999159159159 Significance***b***************a Vegetable yields expressed as annual fresh weight yield,and the yields of wheat and maize on air-dry basis.b Significant differences(p<0.001)between the two cropping systems.Table2Average annual nutrient balance in the two cropping systems(kg haÀ1yearÀ1)Component Greenhouse vegetables Wheat e maize rotationN P K N P K Nutrient(fertilizerþmanure)input4670a a1409a1916a662b110b103b Aboveground nutrient removal342a72a450a316a45b266b Nutrient surplus4328a1337a1466a346b65bÀ163b a Mean values with the same letters for the same nutrient between two cropping systems are not significantly different at the5%level.500X.T.Ju et al./Environmental Pollution145(2007)497e506reflects strong movement of P and K down the soil profile inthe greenhouses resulting from large inputs of P and K fertilizers.parison between the two cropping systems in soil pH and ECSoil pH in the top 90cm of the soil profile was significantly (p <0.001)lower in the greenhouses than the cereal fields (Fig.3A).Soil pH was lower nearer the soil surface in the greenhouses,but averaged over 0e 90cm soil depth was sim-ilar in the cereal fields.Although soil pH in the top 30cm in the greenhouses decreased by 0.52pH units compared with the cereal fields,the value remained high (pH 8).Soil pH de-creased exponentially with NO 3À-N concentrations in all three soil layers (Fig.4),which indicates that the substantial NO 3À-N accumulation was an important factor affecting soil acidifica-tion.This effect decreased with increasing soil depth as re-flected by decreasing determining coefficient in the regression equation with increasing soil depth.In contrast with soil pH,soil EC values at 0e 30and 30e 60cm depths in the greenhouses were significantly (p <0.001)higher than in the cereal fields,while at 60e 90cm there was no significant (p >0.05)difference (Fig.3B).Soil EC was higher near the soil surface,indicatingthat the surface soil in the greenhouses readily accumulated salts.Soil EC vales were lower in the surface soils of the wheat e maize fields,and at 60e 90cm depth were not signifi-cantly (p >0.05)different between the two cropping systems.Soil EC values averaged over the top 90cm of the soil pro-file were highly significantly and positively correlated with NO 3À-N concentrations (Fig.5),indicating that the large amounts of NO 3À-N accumulated were an important factor contributing to soil salinity.The decrease in correlation coef-ficient with increasing soil depth indicates that soil EC was af-fected slightly by NO 3À-N accumulation in the deep subsoil.Variation in the nitrate concentrations at 0e 30cm soil depth explained 95%of the variance in soil EC.parison between the two cropping systems in trace elements and heavy metalsThe available Fe,Mn,Cu,and Zn concentrations at 0e 30cm soil depth in the greenhouses were significantly (p <0.01or 0.001)higher than in the wheat e maize fields (Table 4),and were 1.2,1.3,1.3and 1.4times higher on aver-age,perhaps reflecting the large application rates of fertilizers and manures in the greenhouses.The soil Pb concentrations in the greenhouses were signif-icantly (p <0.05)lower than in the cereal fields (Table 4),perhaps through reduced atmospheric inputs.However,soil Cd concentrations in the greenhouses were significantly (p <0.001)higher than in the cereal fields (Table 4),perhaps due to large application rates of P fertilizers contaminated with Cd.Soil Cd concentrations were significantly and positively correlated with soil Olsen P (y ¼0.0002x þ0.013;r ¼0.6424,p <0.01).4.DiscussionAlthough our survey was a snapshot in time over a one-year period,a substantial quantity of detailed data were obtained on conventional agricultural practice in the management of the two cropping systems in northern China.We compared the fer-tilizer application rates in farming practice with the rates rec-ommended by the local extension service.However,the mineral N fertilizer rate can be substantially reduced by use of the Nmin method both in greenhouse vegetables (He et al.,2006)and in wheat e maize rotations(Chen,2003)be-cause soils in conventional management practice have accu-mulated large amounts of Nmin as shown in this study.Thus,the Nmin method could be readily adopted by farmers to control N fertilizer inputs to minimize soil degradation and negative environmental impacts,especially in greenhouse vegetable production systems.There were very large quantities of residual nutrients in the greenhouse soils after several years of high application rates of fertilizers and manures.Soil OM,TN,mineral N,available P and K,available Fe,Mn,Cu,Zn,Cd and EC also increased while soil pH decreased.Excessive irrigation (usually >1000mm per crop,with two or three crops grown each year)led to leaching of NO 3À-N and K (Cameron et al.,Table 3Comparison between the two cropping systems in soil OM and TN at 0e 30cm depth Cropping system No.of sites Descriptive statistics Soil OM (g kg À1)Soil TN (g kg À1)Greenhouse vegetables 30Mean 16.811.343Range 10.50e 24.020.924e 1.896CV (%)24.6918.51Wheat e maize rotation 30Mean 13.170.965Range 10.89e 15.550.825e 1.274CV (%)9.509.10Significance*********Differences between the two systems in nutrient content are significant at p <0.001.0153045607590NO 3-N (kg ha -1)NH 4 -N (kg ha -1)S o i l d e p t h (c m )0153045607590S o i l d e p t h (c m )AB-+Fig.1.Accumulation of NO 3À-N (A)and NH 4þ-N (B)in soils in the two crop-ping systems (**,***indicate that differences between the two systems at the same soil depth are significant at p <0.01and 0.001,respectively).501X.T.Ju et al./Environmental Pollution 145(2007)497e 5061997;Li et al.,2001;Ju et al.,2004a;Zhu et al.,2005)and even some leaching of P to deeper soil layers.In fact,we mea-sured nitrate concentrations in water leaching to a depth of 1.4m in the soil profile of up to 120e 210mg N L À1after the tomato harvest during the survey year,a value much higher than the maximum permissible limit for drinking water (20mg N L À1)in China.Some studies have shown over 228kg N ha À1leached into groundwater in vegetable fields (Stites and Kraft,2001;Kraft and Stites,2003),resulting in nitrate concentrations in groundwater 3m deep 20times higher than in adjacent cereal fields upstream.High N application rates combined with high soil water contents also contributed significantly high N 2O emission rates in greenhouse vegetable soils (He et al.,2006).Numerous studies have shown that large amounts of accu-mulated nitrate in soils may also stimulate plants,especially leafy vegetables,to absorb and accumulate excessive nitrate (Petrovic et al.,1992;Santamaria et al.,1998;Wang et al.,2001).Humans consume the green soft parts of leaves and stems,and these are the plant parts that accumulate large amounts of nitrate (Walker,1990).Nitrate accumulation in plants has been regarded as harmful to the human body and this has been of great concern to scientists and consumers (Rockman and Granli,1991;L’hirondel and L’hirondel,2002;Addiscott and Benjamin,2004).Studies at Rothamsted Research Station in SE England have shown a marked increase in P concentration in drainagewater to more than 2mg L À1as soon as soil Olsen-P exceeded 60mg kg À1(Heckrath et al.,1995),while Olsen-P in our greenhouse vegetable soils reached 160mg P kg À1on average at 0e 30cm depth,and 97mg P kg À1at 30e 60cm depth in the present rge accumulation of P in soils may have significant effects on the surface-and groundwater envi-ronments and may merit further research in northeast China over the long term.Concentrations of soil micronutrients increased signifi-cantly in greenhouses as a result of large inputs of manure and soil acidification.Soil available Fe,Mn,Cu,and Zn at 0e 30cm depth in both cropping systems were at sufficiency levels (Fe:>4.5mg kg À1;Mn:>5mg kg À1;Zn:>0.5mg kg À1;Cu:>0.2mg kg À1)(Hu and Zhou,2003).Soil Cd concentrations in greenhouses were 2.8times those in wheat e maize fields on average.Fertilizers,manures and at-mospheric deposition may be important sources of soil Cd,which is slowly increasing in many agricultural soils (McLaughlin et al.,1999).The increase in soil Cd concentra-tions in this study may be mainly attributable to large applica-tion rates of manures and P fertilizers.This agrees with the conclusions of Williams and David (1976)who found that soil Cd concentrations (0.008e 0.028mg kg À1)and Cd in wheat grain (0.03e 0.06mg kg À1)were both positively corre-lated with application rate of P fertilizer (0e 60kg P ha À1year À1)after continual application of P fertilizer for five years.In the present study we found that of the P******20406080100120140160180S o i l O l s e n -P (m g P k g -1)******20406080100120140160180S o i l N H 4A O C -K (m g K k g -1)30-60cm 60-90cm30-60cm 60-90cmABFig.2.Accumulation of P and K in soils of the two cropping systems (A:soil Olsen-P;B:NH 4OAc-K)(***indicates that differences between the two systems in nutrient concentration at the same soil depth are significant at p <0.001).***NS0.00.10.20.30.40.50.60.7Vegetable W heat-maizeS o i l E C (S m -1)*********7.87.98.08.18.28.38.48.58.68.7Vegetable W heat-maizeS o i l p H30-60cm 60-90cm30-60cm 60-90cmABFig.3.Soil pH and electrical conductivity (EC)in the two cropping systems (A:soil pH;B:soil EC)(***indicates that differences between the two systems in nutrient concentration at the same soil depth are significant at p <0.001;NS,no significant difference between the two systems at the same soil depth).502X.T.Ju et al./Environmental Pollution 145(2007)497e 506。
2017 年 11 月 25 日托福写作考题
2017 年11 月25 日托福写作考题综合阅读：blue iguanas 减少很难保护1.blue iguanas 和一种green iguanas 很像，green iguanas 对庄家造成破坏，当地人会杀死green iguanas，有时候会误杀blue iguanas2.blue iguanas 的基因多样性较差，不能适应环境3.饲养blue iguanas 很容易生病死亡听力：反对1.人们可以在blue iguanas 上装上塑料贴这样很容易辨识2.可以把其他地区的blue iguanas 引进，在这里杂交，增加基因多样性3.blue iguanas 喜欢照太阳，喜欢深绿色的植物，饲养的过程中可以做出调整，这样就很容易解决得病的问题独立Do you agree or disagree the following statement:The more money a person has, the more should he or she give away to charities. 2017 年11 月25 日托福口语真题解析Task 1Which of the qualities that the parents or family members can help you develop.Self-confidenceKindness Patience Task 2Do you agree or disagree that the determining factor that the successful of students in school is the intelligence?Task 3阅读标题：art students decorate the stairwells 原因1: 让艺术生去画stairwell原因2：在暑假期间装饰听力态度：赞成原因1：对于艺术生来说是个好事，因为平常只有一年一次的展览机会，太少了，而且几天就撤走。
比较对比型英语作文 四六级真题
比较对比型英语作文四六级真题In recent years, the issue of environmental protection has become increasingly prominent. On the one hand, many people argue that economic development should be theprimary focus, and that environmental protection measures are too costly and will hinder progress. On the other hand, there are those who believe that protecting the environment is crucial for the well-being of future generations, andthat we must take action now to prevent irreversible damage.From an economic perspective, it is true that environmental protection measures can be costly. For example, implementing stricter emissions standards for factories and vehicles may require significant investmentin new technologies and infrastructure. This couldpotentially slow down economic growth in the short term. However, it is important to consider the long-term costs of environmental degradation. If we continue to pollute theair and water, we will eventually face health problems, resource shortages, and other serious consequences thatwill ultimately be more costly than the initial investmentin environmental protection.Moreover, there are also economic opportunities in environmental protection. The development of renewable energy sources, such as solar and wind power, has the potential to create new jobs and stimulate economic growth. By investing in clean technologies and sustainable practices, we can build a greener and more sustainable economy for the future.In addition to the economic arguments, there are also ethical and moral reasons to prioritize environmental protection. As stewards of the planet, we have a responsibility to preserve and protect the natural worldfor future generations. By reducing our carbon footprint, conserving natural resources, and protecting endangered species, we can ensure a better quality of life for our children and grandchildren.In conclusion, while there are valid concerns about the economic costs of environmental protection, the long-term benefits far outweigh the short-term challenges. By investing in clean technologies and sustainable practices, we can create new economic opportunities while preserving the planet for future generations.最近几年，环境保护问题变得日益突出。
高二英语生物学原理与生态现象单选题50题
高二英语生物学原理与生态现象单选题50题1.The function of chlorophyll is to ___.A.absorb sunlightB.produce oxygenC.absorb carbon dioxideD.produce water答案：A。
解析：叶绿素的功能是吸收太阳光进行光合作用。
选项B，产生氧气是光合作用的结果之一但不是叶绿素的主要功能；选项C，吸收二氧化碳的主要结构不是叶绿素；选项D，产生水也是光合作用的结果之一但不是叶绿素的直接功能。
2.Which one is not a characteristic of living things?A.GrowthB.ReproductionC.MovementD.Response to stimuli答案：C。
解析：生物的特征包括生长、繁殖、对刺激作出反应等。
并不是所有生物都能运动，比如植物大多数不能自主运动，所以运动不是生物的普遍特征。
3.The basic unit of life is ___.A.cellB.tissueananism答案：A。
解析：细胞是生命的基本单位。
组织是由细胞组成的，器官是由不同组织构成的，生物体是由多个器官等组成的。
4.What is DNA short for?A.Deoxyribonucleic acidB.Ribonucleic acidC.Deoxyribose acidD.Ribose acid答案：A。
解析：DNA 是脱氧核糖核酸的英文缩写。
选项B 是核糖核酸；选项C 和D 不是正确的缩写。
5.Which process involves the conversion of light energy into chemical energy?A.RespirationB.PhotosynthesisC.DigestionD.Excretion答案：B。
解析：光合作用涉及将光能转化为化学能。
小学上册I卷英语第5单元真题[含答案]
小学上册英语第5单元真题[含答案]英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1.I enjoy playing with my toy ________ (玩具名称) in the pool.2.What do we call the study of plants?A. BiologyB. BotanyC. ZoologyD. Ecology答案:B3.__________ (分子式) represents the ratio of elements in a compound.4.What is the opposite of "hot"?A. WarmB. ColdC. CoolD. Spicy答案:B5.The boy has a new ________.6.The _____ (美洲豹) is known for its striking spots and agility. 美洲豹以其醒目的斑点和灵活性而闻名。
7.What do we call the act of providing opportunities for success?A. EmpowermentB. SupportC. PromotionD. All of the Above答案:D8.My mom is a fantastic __________ (谈话者).9.What do we call the process of growing crops?A. AgricultureB. HorticultureC. BotanyD. Forestry10.The chemical symbol for thallium is __________.11.The process of making biofuel involves converting organic waste into _______.12. A __________ is a layer of rock below the soil.13.What is 2 + 2?A. 3B. 4C. 5D. 6答案:B14.My ___ (小狗) enjoys going for walks.15.We are going to ___ cookies. (bake)16.The _____ (野生动植物) depend on local plants for survival.17.I enjoy the sound of __________ during a gentle rain. (滴答声)18.The _____ (garden) is beautiful.19.ration of Independence was signed in ________ (1776). The Decl20.The process of fermentation produces ______ and alcohol.21.What is the capital city of Canada?A. TorontoB. OttawaC. VancouverD. Calgary答案:B22.What is the chemical symbol for gold?A. AuB. AgC. FeD. Pb答案:A Au23.Which instrument is played by blowing air into it?A. GuitarB. DrumsC. FluteD. Piano答案:C24.________ (热带雨林) has a rich variety of plants.25.I see a _____ (rabbit) in the garden.26.What do we call the annual celebration of a person's birth?A. AnniversaryB. HolidayC. BirthdayD. Festival答案:C27.I love visiting the aquarium to learn about ________ (海洋生物) and their habitats.28.The ancient Egyptians believed in the afterlife and were buried with ________ (财宝).29.What is the capital of Portugal?A. LisbonB. MadridC. BarcelonaD. Rome答案:A30.The chemical symbol for carbon is ______.31.I heard a _____ (noise/sound) outside.32. A cheetah is the fastest _______ on land, capable of incredible speed.33.The __________ (历史的传递) relies on storytelling.34.小果子) grows on trees. The ___35.I enjoy _______ (hiking) in the woods.36.The flowers in the garden attract _______ and happy bees buzzing around.bustion is a chemical reaction that produces _____.38.What is the currency used in Japan?A. YenB. RupeeC. PesoD. Dollar39.The squirrel's sharp claws help it climb trees with ________________ (轻松).40.How many zeros are in one hundred?A. OneB. TwoC. ThreeD. Four41.I find ________ (社会学) very interesting.42.What do you call the ocean that is to the east of Africa?A. Atlantic OceanB. Indian OceanC. Arctic OceanD. Pacific Ocean答案:B Indian Ocean43.The ______ is a thin layer of gases around Earth.44. A chemical reaction can be fast or ______.45.The main gas used in welding is ______.46.What is the name of the bird that cannot fly and is native to New Zealand?A. KiwiB. EmuC. OstrichD. Penguin47.What is the name of the famous scientist who proposed the theory of evolution?A. Isaac NewtonB. Albert EinsteinC. Charles DarwinD. Louis Pasteur答案:C48.My brother is interested in _______ (名词). 他想要 _______ (动词).49.The War of was fought between the USA and ________.50.biomimicry) learns from nature for innovation. The ____51. A reaction that absorbs heat is called an ______ reaction.52.The engineer, ______ (工程师), builds bridges and roads.53.What do you call a person who travels in space?A. AstronautB. PilotC. ScientistD. Explorer答案:A54.What do we call the fluffy white substance that falls from the sky in winter?A. RainB. HailC. SnowD. Sleet答案:C55.What is the opposite of big?A. LargeB. SmallC. HugeD. Tall56.The __________ (历史的探讨) encourages open dialogue.57.The chemical symbol for argon is _______.58.The __________ (历史研究) reveals important lessons.59. A _____ (猴子) can use tools to get food.60.What is the name of the famous artist known for his "Water Lilies"?A. Claude MonetB. Vincent van GoghC. Pablo PicassoD. Henri Matisse答案:A61.Which vegetable is orange and long?A. CucumberB. CarrotC. PotatoD. Eggplant62.The cake is _____ for the party. (ready)63.The cake is very ___. (rich)64.The _____ (sage) plant is drought-resistant.65.Rabbits like to dig _________. (洞)66.How many points is a touchdown worth in American football?A. 5B. 6C. 7D. 867.My brother loves going to ____ (amusement parks).68.The man is very ________.69. (88) is a famous mountain in Japan. The ____70.What is the name of the famous scientist known for his laws of motion?A. Isaac NewtonB. Albert EinsteinC. Nikola TeslaD. Stephen Hawking71.What is the largest mammal in the world?A. ElephantB. Blue WhaleC. GiraffeD. Hippopotamus答案:B72.What is the capital of South Africa?A. Cape TownB. PretoriaC. JohannesburgD. Durban答案:B73. A __________ is a landform created by the accumulation of glaciers.74.soil) is crucial for agriculture. The ____75. A __________ (温室) is a good place for plants.76.The ____ is a playful animal that loves to splash in water.77.What do we call a small, round snack made from corn?A. ChipB. PretzelC. PopcornD. Crackers78.Which of these is a popular fruit?A. TomatoB. CarrotC. AppleD. Lettuce答案:C79. A solution with a low concentration is known as a ______ solution.80.My sister loves to take care of her ______ (小猫).81.I have a _____ (遥控飞机) that can fly high.82.Cleopatra was the last pharaoh of _____.83.My ________ (玩具名称) helps me practice my spelling.84.What is the main gas we breathe?A. OxygenB. Carbon DioxideC. NitrogenD. Hydrogen答案:A85.What is the primary ingredient in a shepherd's pie?A. BeefB. ChickenC. LambD. Pork86.Light from the sun takes about eight ______ to reach us.87.The chemical formula for sodium bicarbonate is __________.88.I can ______ (count) to in Spanish.89.Certain plants can be used to create natural ______ against pests. (某些植物可以用来创建自然屏障，抵御害虫。
高二英语植物与环境单选题50题
高二英语植物与环境单选题50题1. The roots of plants play a crucial role in the environment. They help to ____ water and nutrients from the soil.A. absorbB. produceC. releaseD. transform答案：A。
解析：植物的根在环境中的重要功能是从土壤中吸收水分和养分。
选项A吸收符合根的功能；选项B产生不符合根的功能；选项C释放不是根对水和养分的主要作用；选项D转化也不是根对水和养分的主要作用。
2. Leaves are the main organs for plants to carry out photosynthesis. Which of the following is essential for photosynthesis in leaves?A. OxygenB. Carbon dioxideC. NitrogenD. Hydrogen答案：B。
解析：叶子进行光合作用时，二氧化碳是必不可少的原料。
选项A氧气是光合作用的产物；选项C氮气不是光合作用的必要物质；选项D氢气不是光合作用的必要物质。
3. The stem of a plant has the function of ____.A. only supporting the plantB. transporting water and nutrientsC. producing seedsD. absorbing sunlight答案：B。
解析：植物的茎具有运输水分和养分的功能。
选项A 茎不仅仅是支撑植物，还有运输等功能；选项C茎不产生种子；选项D茎不吸收阳光。
4. Some plants have very long roots. These long roots can help the plants ____.A. get more sunlightB. compete for more space undergroundC. produce more flowersD. resist strong winds better答案：B。
2013年3月3日托福阅读考题解析
2013年3月3日托福阅读考题解析第一篇一个讲coevolution 植物除了正常外观（比如刺，滑腻腻的叶子）之外还会分泌有毒的东西（second compound）防止虫子，虫子也会进化，进化的虫子就有东西吃，而且没人跟他抢吃的。
有的还会将植物分泌的有毒物用来预防鸟，鸟中毒以后会吐，下次就会记得不吃这种虫子了。
也有的鸟吃了不会吐。
第二篇二是讨论要不要清理海上残留的oil，马上清理或者让自然natural flushing来清理。
讲了三种油的分类，词汇考了resilient这个印象深刻因为不懂什么意思，stimulate。
难度是三篇中最大的第二篇我补充一下细节，文章主要是讲海上漏油漏到沼泽地然后要不要清理，对生态环境的影响主要取决于油的种类，湿地的种类和季节。
说有些沼泽很多植物都因为油发芽也不能开花，开花也不能结果，结果也不能发芽...另一些沼泽有比较小强的植物比如Spartina 米草属，只要油不渗到地底下，他们扎得很深的根不受影响，他们就继续顽强地活着。
这里Spartina有两类，前者比后者更敏感一些。
然后讲油的种类，说油蒸馏以后有很多可用成分，分蒸馏过还是没蒸馏过的油。
蒸馏的原理是沸点不同，低沸点的有毒易挥发，高沸点毒性弱不易挥发，中沸点又有毒又不易挥发，危害最大。
然后讲了到底该不该人工移除油，措施是把那些油油的湿地的植物都铲平，科学家观察了一个湿地发现非常的resiliet，油基本没起啥作用，最后结论是只要油不会呆那太长时间就按兵不动"NO ACTION",因为人工移除反而危害更大。
大概就酱。
Oil spillleakage of petroleum onto the surface of a large body of water. Oceanic oil spills became a major environmental problem in the 1960s, chiefly as a result of intensified petroleum exploration and production on continental shelves and the use of supertankers capable of transporting more than 500,000 tons of oil. Spectacular oil spills from wrecked or damaged supertankers are now rare, because of stringent shipping and environmental regulations. Nevertheless, thousands of minor andseveral major oil spills related to well discharges and tanker operations are reported each year, with the total quantity of oil released annually into the world's oceans exceeding 1 million tons. The unintentional or negligent release of used gasoline solvents and crankcase lubricants by industries and individuals greatly aggravates the overall environmental problem. Combined with natural seepage from the ocean floor, these sources add oil to the world's waterways at the rate of 3.5 to 6 million tons a year.第三篇城市规划。
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248
s Transportation Research Record 1802 Paper No. 02-2143
Comparison of Greenshields, Pipes, and Van Aerde Car-Following and Traffic Stream Models
Hesham Rakha and Brent Crowther
Microscopic simulation models use car-following behavior to model the interaction of a vehicle and the preceding vehicle traveling in the same lane. The process of car-following is modeled as an equation of motion under steady-state conditions plus a number of constraints that govern the behavior of vehicles while moving from one steady state to another (decelerating and accelerating). Typically, up to two constraints are considered. The first constraint governs the vehicle acceleration behavior, which is typically a function of the vehicle dynamics. The second and final constraint ensures that vehicles have a safe position relative to the lead vehicle in order to decelerate to a complete stop without colliding with the preceding vehicle in the event that the preceding vehicle decelerates to a complete stop. Consequently, calibration of the car-following behavior within a microscopic simulation model can be viewed as a two-step process.
In the first step, the steady-state behavior is calibrated, followed by a calibration of the non-steady-state behavior. The calibration of steady-state behavior is critical because it dictates the maximum roadway throughput (capacity), the speed at which vehicles travel at different levels of congestion (traffic stream behavior), and the spatial extent of queues when vehicles are fully stopped ( jam density). Alternatively, the calibration of non-steady-state behavior, which in most cases is less critical, influences how vehicles move from one steady state to another. Thus, it captures the capacity reduction that results from traffic breakdown and the loss of capacity during the first few seconds as vehicles depart from a traffic signal (commonly known as the start loss). Under certain circumstances, the nonsteady-state behavior can influence steady-state behavior. For example, vehicle dynamics may prevent a vehicle from attaining steadystate conditions. A typical example of such a case is the motion of a truck along a significant upgrade section. In this case, the actual speed of the truck is less than the desired steady-state speed because vehicle dynamics do not permit the vehicle from attaining its desired speed. The analysis of such instances is beyond the scope of this paper. OBJECTIVES The objectives here are twofold. First, the Greenshields, Pipes, and Van Aerde (1; 2, pp. 334–341) car-following models are presented and compared for the modeling of steady-state conditions that occur when the lead and following vehicles cruise at equal speeds, when the differences in speeds are relatively small so that they cannot be perceived by the driver, or when the distance headway between the two vehicles is significantly long so that the behavior of the lead vehicle has no influence on the behavior of the following vehicle. An analysis of non-steady-state conditions, which include moving between steady states that result from differences in vehicle speeds, is beyond the scope of this paper and will be presented in a forthcoming paper. Second, an analytical formulation is developed that relates the roadway capacity to the Pipes model driver sensitivity factor. This important relationship between microscopic and macroscopic traffic behavior provides a unique opportunity to calibrate microscopic car-following models using macroscopic loop detector data. It should be noted, however, that the mechanics of the calibration tool required to conduct such a calibration effort is beyond the scope of this paper but will be presented in a forthcoming effort. Instead, the various calibrated models are compared to demonstrate differences in car-following behavior without describing how these models were calibrated to field data. First a brief background of car-following models is provided here that describes the behavior of vehicles as they follow a lead vehicle.