生物质能源生产的生态环境影响

June 2010Journal of resources and EcologyVol 1. No. 2J. Resour.Eco.20101(2)110-116DO:103969/ J. Issn.1674-764×201002.002ArticleEco-environmental Impact of Bioenergy productionJohn W. Bickham' and Mark A. thomas1 Center for the Environment, Purdue University, 266 Mann Hall, 203 S Martin Jischke Drive, West Lafayette, IN 47907, U.S.A2 Department of Agricultural and Biological Engineering, Purdue University, 225 S. University Street, West Lafayette, IN 47907, U.S.AAbstract: This paper focuses on the eco-environmental aspects of u.s. biofuel production, a grand energyhallenge with an important role in addressing new alternative energy sources. Policy driven approacheshave made U.s. biofuels attractive for economic, environmental and strategic reasons with a potential toimprove national security issues. Despite the many potential benefits of biofuels we will examine causefor concerns relating to biofeedstock supplies, agro-chemical usage on intensively managed landscapesand potential impacts to terrestrial wildlife in North America. The environmental and economic effects offuture biofuels are generally perceived as positive; nonetheless, it will be critical to peruse and develop abiofuels economy with caution to safeguard systems sustainability.Key words: biodiversity; biofuels; wildlife; terrestrial habitats; conservation; agricultural ecosystems1 Introductioneconomy of rural America by providing additional itcome sources to local producers via feedstock productionBiofuels are attractive for economic, environmental and Notwithstanding that the environmental and economic ef-strategic reasons. Reducing our dependency on foreign oil fects of biofuels are generally perceived as positive: weis a key national security issue. The United States derives should develop our biofuels economy with caution. Therebiofuels from corn, to produce ethanol, and soybeans to exist causes for concern that suggest we must take care inproduce biodiesel. In some tropical countries, sugar cane how we manage and develop our biofuel systems in orderis used to produce ethanol. Brazil has derived great eco- to ensure that society reaps the maximum benefits withnomic benefit from sugar cane derived biofuels and has the least risk to the environment. As an example, in thelargely freed itself from dependence on foreign oil. In ad-case of cellulosic biofeedstock production, it will be critidition, biodiesel can be derived from palm oil and other cal to balance harvesting unprocessed agricultural cropplants that grow well in tropical countriesresidues or dedicated energy crops for biofuels owing toAlthough corn and soybeans are excellent sources of the need to protect soil and water resources(Engel et albiofuels, cellulosic feedstocks clearly are the wave of the 2010: Cruse et al. 2009)future. However, regional adaptability, productivity andsustainability are factors that will influence feedstock se-2 Causes for concernlection, which is expected to vary across geographic land- In 2008, there were six existing ethanol refineries in Indiscapes(Engel et al. 2010). Hybrid poplar(populus hybrid ana, six new refineries under construction, and plans foL ) switchgrass(Panicum virgatum L ) miscanthus(Mis- 16 more. Once the 12 plants, existing and under construc-canthus giganteus L ) and even managed prairie ecosys- tion are on line, they will produce 800 million gallons oftems are potential sources of cellulosic biofuels. If we can ethanol per year and consume 300 million bushels ofsolve the problems of effectively transforming this bio- corn; roughly 30 percent of Indiana's 2008 corn produc-mass into cellulosic ethanol or other fuels, there will be tion. If the 16 planned refineries are built, then about 75significant environmental gains in greenhouse gas reduc- percent of Indianas corn crop could be used to producetions as opposed to grain-based feedstocks and processes grain-based biofuels. In the absence of new technologiescurrently availableand alternative feedstock sources, the potential effects ofProduction of biofuels would potentially benefit the biofuel demands on grain-for-food production would be中国煤化工Received: 2010-05-18 Accepted: 2010-06-07CNMHGCorresponding author: John w. Bickham. Email: bickham(@purdue. eduJohn W. Bickham and Mark A. Thomas: Eco-environmental Impact of Bioenergy Productienormous. Another cause for concern is simply the scale cides, and herbicides, which will further impair waterof our consumption of fuel for transportation. If 100 per- quality. The Corn Belt contains some of the most producent of U.S. corn and soybean production as it stands to- tive agricultural land in the United States, and is a primeday were used to produce biofuels, it would produce only target for production of biofuels. The Corn Belt also overenough to replace 12 percent of gasoline and 6 percent of lays an area drained by several major tributaries to thebiodiesel based on current usage(Hill et al. 2006)Mississippi river, the largest river in the United StatesMany of the anticipated environmental benefits could (Fig. 1). This is the sewage system, if you will, that drainsbe partially offset by negative impacts, especially if corn the agricultural heartland of the country. As the biofuelsis the main source of biofuels(Engel et al. 2010; Thomas economy grows, there will likely be a need to rely onet al. 2009). If corn production significantly increases, the more intensive use of nitrogen and pesticides which wiresult will be more air pollution from the fossil fuels used impact water quality. a hypoxic zone appears each year inin farming and transporting. In addition, some ethanol the Gulf of Mexico, which is thought to be the result ofplants use approximately four gallons of water for every fertilizers from the Corn Belt that drain into the Mississipgallon of ethanol produced, so water usage will be an im- pi river, it is decimating to fisheries in the Gulf and im-portant issue in some states until better methods are devel- pacting the way of life for those who fish in that regionoped(Keeney et al. 2006). As the prices of corn and soy- The projected increase in agricultural production necesbeans rise, there will be pressure to use marginal lands sary to satisfy our nations demand for biofuel, will putand lands in conservation easements, resulting in a loss of more pesticides and fertilizers into the Mississippi, reducwildlife habitat. Corn ethanol produced in refineries pow- ing water quality and increasing the size of the anoxicered with coal may result in a net increase in greenhouse zone in the Gulf of mexico. This will directly subtractgas emissions(DOE 2007). To achieve our ultimate goal from the bottom line of the nation s economic and enviof reducing COz, we will need to make significant gains ronmental profitabilityin more efficient use of energy and continue to pursue al- In addition to changing agricultural practices related toternative energy sources such as wind and solar, as well biofuels, water quality faces an additional challengeas advanced biofuelsEmerging diseases affect not just public health, but can af-fect crop plants as well. Soybeans generally require fewer2.1 Fertilizer, pesticides and emerging diseasesinputs, such as fertilizers and pesticides, as opposed toAnother concern is increased use of fertilizers, insecti- corn. Nevertheless, Indiana(a Corn Belt state)has aboutig. 1 Maps showing the Miern Corn belt and the sub-basins ofsissippi River whichit. Midwestern agriculturals0D KilometersCorn Belttems are typically a mosaic of cropMisssppLANcAaa bya Rve Basw aNdThe UAwersMy tExas&lands. woodlots, wetlands and oth-er natural areas as seen in the photo( Photo by J W. Bickham)HCNMHG112Journal of Resources and Ecology Vol 1 No. 2, 201C700 000 acres of soybeans that are currently treated with way. This is just one example out of myriad of species offoliar fungicide. An emerging agricultural disease, Asian neotropical migrants that do this. If these birds areSoybean Rust is already present in the United States and stressed because of increased contaminants or lack ofhas been detected in Indiana but not yet firmly estab- food, they wont make it. Hummingbirds live on the edgelished. According to Leighanne Hahn of the Office of In- of survival, as do many other species. Changes in agriculdiana State Chemist, when Asian Soybean Rust becomes tural practices related to the biofuels economy could imestablished, an estimated 5.5 million acres will be treated pact populations of neotropical migrants throughout thewith fungicides in Indiana alone. The modeled concentra- Corn Belttions of off site movement of 14 fungicide active ingrediHow can we manage agricultural ecosystems to preventents allowed for control of Asian Soybean Rust predict these adverse effects? First, we have to change our percepseveral potential impacts of fungicide use. These impacts tion of ecosystems. An ecosystem is not just a corn fieldinclude exceeding lethal concentrations to aquatic organ- or a woodlot. It is composed of a number of habitatsisms(fish and aquatic invertebrate species), reproductive which, altogether, provide invaluable services such as pol-ffects to specific exposed bird species and possible respi- lination, wildlife habitat, clean water, recreation, andratory effects on bats depending upon the product applied. food. Changing any one aspect of the agriculturalA nearly &-fold increase in the application of pesticides tem will have a domino effect on these services.would severely impact water quality in the rivers and The Midwestern agricultural ecosystem, for examplestreams of the Mississippi drainage Areais highly fragmented. Croplands are interspersed with riparian habitats(rivers and streams), woodlands, and other2. 2 Effects on wildlife a case of the hummingbird onmicrohabitats to form a mosaic. This complex landscaplifes edgeprovides insects and other pollinators, wetlands to purifyWildlife likely will suffer from increased crop production. the water, habitat for wildlife, and recreation, in additionThe central flyway for migratory birds in North America to providing food. As the price of corn goes up, the valuefollows the Mississippi River which funnels migratory of those lands rises. and much of what is now wildlifebirds from Alaska, Canada, the Midwest, and the great habitat could be turned into cropland. Losing this valuPlains into Louisiana and Texas(Fig. 2 ). The woodlands able wildlife habitat has its own hidden cost in the loss ofand wetlands in this corridor represent important habitat ecosystem services. In our deliberations about how to profocluding the neotropical migrants, duce the energy crops we need, we must consider all as-many of which already are highly vulnerable due to defor-pects of changing this landscapeestation throughout much of their nesting rangeThe Ruby-throated Hummingbird(Archilochus colu- 3 Grand challengesbris) is a neotropical migrant common in the eastern Unit- The environmental challenges we face in converting toed States. Hummingbirds are the most fantastic flyers in biofuels are daunting. How can we mitigate some of thethe avian world. Adapted for feeding on nectar, they fly adverse effects on climate change, biodiversity, forestsup to a flower, and because their wings beat in a figure wildlife, and water and air quality? As the price of corneight and extremely fast (50-75 beats per second), they and soybeans rises, more of our natural lands will be con-can hover, flying forwards and backwards, like a tiny hell- verted to managed systems for energy production. Thecopter. They have the highest metabolic rate of any bird, United States currently has 14 million hectares(35 miland the nectar they eat is a high energy source. Their met- lion acres)of land in a program called the Conservationbolic rate is so high that at times, instead of going to Reserve Plan, which sequesters 48 million metric tons ofsleep at night, they go into torpor to save energy. Torpor co,. In 2010. however. contracts for about 11 millionis a reduction in their body temperature, metabolic rate, hectares(26 million acres)expire(food&Water Watchheart beat, etc. and is especially used in times of food 2007). If the price of corn is high, much of those landshortage. This little bird migrates down the Mississippi will revert from wildlife habitat to corn croplandFlyway and lands, as do many of the neotropical nConversion to cropland will contribute to deforestationgrants,at High Island on the coast of Texas near Louisi- both in the United States and globaana. High Island, well known to birdwatchers, is an im- estimates by the United Nation's Food and Agricultureportant resting place before the hummingbirds must fly Organization1中国煤化工 at a world-widenonstop across the gulf of mexico to the Yucatan Peninsu- rate of 13 millCNMacres)per yearla, a trip of 600 miles. there is nowhere to rest along the much of that iputed wo conventagriculture, butJohn W. Bickham and Mark A. Thomas: Eco-environmental Impact of Bioenergy Producti113biofuel cropping will exacerbate the deforestation prob- tion are located within hotspots of biodiversity, includinglem(FAO 2006)the Amazon forest, tropical West Africa, and tropicalDeforestation and crop conversion might also increase Southeast Asia. The biodiversity hotspots comprise 34the rate of extinction of species. The current extinction gions covering only 2.3 percent of the Earths surface butrate is nearly 1000 times the background rate and may holding 75 percent of the planets biodiversity. In one ofreach as high as 10 000 times greater over the next centu- these hotspots, the Amazon, forests are being rapidlyry. There are about 1.6 million species of all organisms cleared for agriculture. In tropical Southeast Asia, manyformally described by scientists, out of an estimated total forestedproduce pfcof 7 to 10 million species. Most of the biodiversity of biodieselFrom this, it is likely that therate of extinction, two thirds of all species will disappear on ction of biofuels, particularly in the tropics, will in-the planet has never been described. In fact, most species producin the next 100 years or so. This is an extinction rate the To illustrate how little we know about biodiversity andEarth has not experienced for approximately 65 million how much work remains to be done, consider the littleyears,and the reason for the current rate is human impact Yellow Bat, the smallest bat in the Western hemisphere. Iton global ecosystemsweighs only about 3 grams and is the size of the end ofRecently, the first complete genome sequence of a tree, your thumb When John W. Bickham first started workingthe black cottonwood, was described making this one of a on this bat about 35 years ago, it was considered a singlehandful of species for which such a database exists. It is a species, rhogeessa tumida. After a series of genetic studgreat step forward to have achieved this level of under- ies, there are now 8 described and at least 2 yet to be destanding for a tree with important biofuels implications. scribed species of Little Yellow Bats(Baird et al. 2008)But it stands in stark contrast with our understanding of Unlike most species of bats which are highly mobile, Litmost of the world,'s species for which we dont even have tle Yellow Bats don' t migrate or disperse very far. Populaa name. We have never seen many of them. Nonetheless, tions have developed genetic and chromosomal differencevery species is of potential benefit to mankind, each a es indicative of species distinction. We were able to deterjewel in the crown of Earthmine by chromosomal and molecular genetic studies thatMany of the areas experiencing high rates of deforesta- there are 10 different lineages of this mammal, each a disPhoto credit: John w. BickhamSourceMapimageproducedbyBirdnature.comig. 2 The Mississippi flywayis a migratory route for manyspecies of birds, includingraptorsserinesy neotropical mi-grants, such as the Rubyhroated Hummingbird pictured here. cross the gulf of中国煤化工 eir way to theula of mexicoCNMHG114Journal of Resources and Ecology Vol 1 No. 2, 201Ctinct biological species(Fig 3). The number of species of servation goals cannot be achieved without knowledge ofmammals, recently thought to number about 4000, has ap- the genetic diversity within a species, which is a fact wellparently been underestimated by 25 to 50 percent. If the known to another management group with which John Wbiodiversity of mammals is not yet well documented, Bickham is involved, the International Whaling Commis-imagine then the numbespecies of soil fungi, rainforestsion(wc)insects, or any of the other obscure groups of organisms John w. Bickham's research has led him from thethat remain to be identified. There is an enormous amount smallest of bats to one of the largest organisms on Earthof work to do before we have an adequate inventory of the bowhead Whale, which weighs up to 60 tons. It sum-the diversity of life on Earthmers in the northern Bering Sea and migrates into theBiodiversity is more than just lists of species, it is also Beaufort Sea, where it summers and feeds along the Canagenetic variability within species. In John W. Bickham's dian eastern Beaufort Sea. In the fall it migrates back tolab, we are also engaged in studies using genetics to assist its winter range in the Bering Sea. during the Spring andefforts at conservation. Since the early 1990s, John W. Fall migrations it is hunted by Alaskan Eskimo villages.Bickham have studied Steller sea lions, sampling the ani- These communities depend on the bowhead whale as amals throughout their range from central California to major component of their subsistence diet. The bowheadAlaska, across the Gulf of Alaska and Aleutian Island hunt is thought to have occurred for the past 2000 years.chain to the Sea of Okhotsk in Russia. We have sampled For anyone who hunts or fishes or has an interest in tradivirtually every population of the species. This species tional Native American culture, this is a truly remarkablebreeds at rookeries, where skin biopsies are taken from event that takes place in Barrow, Alaska, and other villag-the flippers of the pups. We have sequenced mitochondri- es. The harvest of this Great Whale is regulated by theal DNA (mtDNA) control regions from about 2500 pups, IWC. As a member of the Us delegation to the scientificmaking this one of the most detailed studies of population committee of the iwC, for the past six years John Wgenetics for any wild mammal. Three distinct genetic Bickham and his colleagues have been conducting an instocks or populations have been identified. These stocks tensive study of the genetics of this population. The goalare best managed and conserved as separate entities. a is to determine whether there are multiple genetic stocksprecept guiding conservation biology is the need for pres- within the population, which could change how these aniervation of genetic diversity because as genetic diversity mals are managed and potentially the number of animalsdeclines, the probability of extinction rises. Clearly, con- allocated to the hunt. Our lab developed a dataset thLittle Yellow BatRhogeessa tumida complexatR10516(Rhogeessa tumida complex)illustrates the need for contin-ued bio-systematic studies todocument biodiversity. Genet-ic studies in this complexhave revealed hidden diversi-ty and increased the numberThe deep branches of the phygenetic tree, based on mtD-TK45014Photo credit: John w. BickhamNA sequences(adapted fromBaird et al. 2008)are indica-tive ofof genetic isolati中国煤化工0005 substtutionssiteCNMHGJohn W. Bickham and Mark A. Thomas: Eco-environmental Impact of Bioenergy Producti115was analyzed by scientists from four U.S. universities and we infer about the future in Indiana or any place that willgovernment labs as well as by scientists from Japan and experience shifts in agricultural production toward biofuNorway. No evidence of any stock structure was found, el? What are the prospects for protecting biodiversity? Inso the quota was renewed for another 5-year period after diana is a key location in the central flyway of birds andthe 2007 IWC meeting. The IwC conducts similar genet- is also home to other species at risk including many freshic studies on each species of great Whale because the con- water mollusks that are unique to the area and sensitive toservation of genetic diversity within species is recognized water quality changes. Terrestrial habitats are alreadyas a fundamental management goal by the organization. highly fragmented and disturbed in most areas. Over sev-Ideally, not just whales but every species needs this kind eral decades, Indiana's landscape has transformed fromof attentionvirgin forests to intensively managed agricultural fields4 Integrated strategiesdominated by corn and soybean production. In westernOhio. the drew woods is one of the few areas dedicatedBest management practices for our changing agricultural to maintain its virgin oak maple forest to help preserve itslandscape will require the development of integrated strat- biodiversity. Ohio has about half a dozen species of Am-egies, for which Purdue University has a number of bystoma salamanders and the most one finds in typicalunique capabilities. The role of the Water Quality Field habitats is one or two. Six species of this salamander ocStation(WQFS), established in 1993, is to test the impact curs in that small, six-hectare(15-acre), forest of Drewof various farming practices on water quality. The WQFS Woods This one small protected woodland has preservedhas gathered nearly 14 years of data on cropping treat- an impressive diversity of plants as well as animals and isments, particularly corn and soybean, as well as native evidence of the natural forests that existed prior to theprairie grasses. The instrumentation the wQFS has devel- Midwest becoming the Corn Belt(Darke County Parksoped continuously measures weather and soil leachate in 2010)different micro-watersheds(hydrologically isolated plots)and periodically measures gas flux at the soil surface on a turbed wildlife habitats. Populations of flora and faunaseries of plots that can be manipulated for different treat- found in that region are vulnerable to further disturbancements, crops, fertilization, pesticides, and harvesting prac- As we convert our agricultural system for the productiontices. Each of these plots is large enough to be harvested of bioenergy in hopes of maintaining our way of life, weusing the mechanized equipment normally used to harvest must consider our responsibility to the environment andcorn fields and soybean fields. The flux of greenhouse the organisms at risk of extinction from pollution, defores-gasses at the soil interface and the water that leaches out tation, and loss of habitat. These are known consequencesof the cropland is monitored over time. During a rain of increased agricultural production. We must not overevent, water flows through a series of tile drains into a col- look our environmental footprint on the largest and mostlection area and is subsequently tested for levels of ni- appealing, or even the smallest and least charismatic, oftrates,dissolved organic carbon, persistence of bacterial Earth's organisms. Notwithstanding the environmental ispathogens, and hormones and antibiotics from application sues and concerns raised here, we are cautiously optimisof manuretic about biofuels and the positive role that they will playIn 2007, the wQFS began to focus on a variety of bio- in our future economy. Our ability to engineer more effifuel production systems, monitoring plots of crops such cient refining techniques and develop better strains ofas big bluestem, a low-input, native prairie grass; corn corn as well as cellulosic crops will continue to shift thand soybean crops in rotation using recommended fertiliz- balance towards better environmental effects. At the samer rates; continuous corn cropping with and without re- time, a clear understanding and dialogue of all of the envi-moval of residue; and miscanthus (Miscanthus giganteus ronmental effects of biofuels, positive and negative, isL )and switchgrass (Panicum virgatum L ) all of which needed to highlight and address potential concernsare proposed biofuels feedstocks. The aim is to measurewater quality under different cropping systems. This facil- Acknowledgementsity is poised to determine the optimal crop rotation system This study and the travel of John W Bickham and Mark A. Thomasand management practices for producing biofuelswere supported by a grant from the Lilly Endowment, Inc. awarded5 The lesson from midwestthrough Purdue中国煤化工 onment at Discov-ery Park. Th(project numberTHCNMLA the USDA-NIFAConsidering all aspects of biodiversity patterns, what canJournal of Resources and Ecology Vol 1 No. 2, 201CReferencestion modeling. Future Science Group: Biofuels, 1(3): 463-477FAO. 2006. Global forest resources assessment 2005: Progress towards sus-Baird A B, D M Hillis, JC Patton and J w Bickham. 2008. Evolutionary histainable forest management. Food and Agriculture Organization of thetory of the genus Rhogeessa( Chiroptera: Vespertilionidae)as revealed byNations, Rome. FAO Forestry, Paper No 147mitochondrial DNA sequences. Journal of Mammalogy, 89(3): 744-754Food Water Watch. 2007. The rush to ethanol: not all biofuels are createdCostello C, W M Griffin, A E Landis, and H S Matthews. 2009. Impact ofequal. Analysis and recommendations for U.S. biofuels policy, Foodbiofuel crop production on the formation of hypoxia in the Gulf of meWater Watch and Network for New Energy Choices in collaboration withco Environmental Science Technology, 43(20): 7985-7991nstitute for Energy and the Environment at Vermont Law School. AvailCruse R m and C G Herndl. 2009. Balancing corn stover harvest for biofuelsableathttp:/kansas.sierraclub.org/wind/rushtoethanol-reporT.pdfLastaccessed: May 17, 2010with soil and water conservation. Journal of Soil and Water Conservation, Hill J, E Nelson, D Tilman, S Polasky and D Tiffany. 2006. Environmental,64(4):286-291DarkeCountyParks.2010.drEwWoodsAvailableat:http:/www.darke-economic, and energetic costs and benefits of biodiesel and ethanol bofuIntyparks, org/pops/parks drew.htm. Last accessed: May 17, 2010els. Proceedings of the National Academy of Sciences, 103(30): 11206DOE. 2007. Ethanol: the complete energy lifecycle picture. United States Keeney D and M Muller. 2006. Water use by ethanol plants: Potential chalDepartmentofEnergy:SecondrevisededitionAvailableathttp://wwwlenges. Institute for Agriculture and Trade Policy, 1-8transportation anl. gov/pdfs/TA/345.pdf.Thomas M A, B A Engel and I Chaubey. 2009. Water quality impacts of cornEngel B, I Chaubey, M Thomas, D Saraswat, P Murphy and B Bhaduriproduction to meet biofuel demands. Journal of Environmental Engineer-2010. Biofuels and water quality: Challenges and opportunities for simula-ing-ASCE,135(1):l123-113生物质能源生产的生态环境影响John w Bickham Mark a. thomas1普渡大学环境中心,印第安纳州,IN47907,美国2普渡大学农业与生物工程系,印第安纳州,IN47907,美国摘要:生物质能源生产是能源发展领域的重大挑战,在解决新的替代能源中扮演着重要角色。本文着重论述了美国生物能源生产的生态环境问題。从经济、环境和战略方面考虑,生物能源有望提高囯家安全,因而受政策驱动的美囯生物能源生产技术备受注目。尽管生物能源具有诸多潜在效益,但是在北美,生物原料供应、髙强度经营的土地上农药使用及其对陆地野生动物的潜在影响等令人担忧,我们分析了其中的原因。通常认为,未来生物能源的环境、经济效应是正面的;然而,谨慎地审视和发展生物能源经济以倸护生态系统的可持续性显得至关重要。关键词:生物多样性;生物能源;野生动物;陆地生境;保护;农业生态系统HCNMHG