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361.
The large majority of biofuels to date is "first-generation" biofuel made from agricultural commodities. All first-generation biofuel production systems require phosphorus (P) fertilization. P is an essential plant nutrient, yet global reserves are finite. We argue that committing scarce P to biofuel production involves a trade-off between climate change mitigation and future food production. We examine biofuel production from seven types of feedstock, and find that biofuels at present consume around 2% of the global inorganic P fertilizer production. For all examined biofuels, with the possible exception of sugarcane, the contribution to P depletion exceeds the contribution to mitigating climate change. The relative benefits of biofuels can be increased through enhanced recycling of P, but high increases in P efficiency are required to balance climate change mitigation and P depletion impacts. We conclude that, with the current production systems, the production of first-generation biofuels compromises food production in the future. 相似文献
362.
At the mid-twentieth century the pace of the transformation of the Swedish forest increased. New methods; large-scale clearcutting, mechanization of logging and planting of seedlings were developed. Chemicals were used to control insects and unwanted tree species. The aims of this study were to elucidate the timing, chain of events and the spatial extent of the large-scale spraying of phenoxy acids in Swedish forests and the drivers for this practice. More than 700 000 hectares of productive forest land was sprayed and the main driving force was a strong will to transform the forest into high-yield coniferous forest plantations. We conclude that; (1) the use of herbicides in forestry in Sweden was done on a very large scale in the period 1948–1984, (2) the ecosystem legacy of herbicide spraying must be investigated and (3) a homogenous cadre of like-minded professionals working across commercial companies, state agencies and universities is dangerous.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01660-5. 相似文献
363.
The Swedish parliament has decided that the use of mercury (Hg) in society should be phased out by the target year 2000 and
substituted with alternative, less harmful elements or compounds. This is to reduce exposure to the toxic heavy metal, levels
of which have increased two to seven times in the Swedish environment during the last century. Mercury in products and goods
in use in Sweden has been estimated at 100 tonnes Hg, which will slowly be released into the environment if no preventative
measures are taken. To avoid handing over unsolved environmental problems and connected costs to future generations, the Swedish
government commissioned the Swedish Environmental Protection Agency (EPA) to improve the efficiency of Hg collection and to
find a solution for terminal storage of the waste. The result is that the Swedish EPA considers deep storage in rock, accompanied
by technical measures to further reduce the risk of future Hg emissions to be the safest method. It has funded approximately
50 projects with the goal of spreading information about the Hg problem and removing Hg from society. The projects have focused
on areas where there is a great risk of Hg in products and goods entering the environment. About 6 tonnes Hg has so far been
collected in these projects – end of 1999 – and the cost of the Hg collected has varied between 70 and 1300 US$ kg–1 Hg. The projects were more cost-effective than traditional inspection by an official due to local participation, use of Hg-tracker
dogs, and employment of professional electricians in the search for Hg. The involvement of school children and the public
has resulted in an increased awareness of environmental matters, and, together with the emptying of water seals, reduced Hg
levels in municipal sewage sludge.
Electronic Publication 相似文献
364.
Skaugset NP Ellingsen DG Dahl K Martinsen I Jordbekken L Drabløs PA Thomassen Y 《Journal of environmental monitoring : JEM》2012,14(2):353-359
Alumina used in the production of primary aluminium contains Be which partly vaporises from the cryolite bath into the workroom atmosphere. Since Be may be toxic at lower exposure levels than previously thought, the personal exposure to Be among workers in 7 Norwegian primary smelters has been assessed. In total, 480 personal Respicon? virtual impactor full shift air samples have been collected during 2 sampling campaigns and analysed for water soluble Be, Al and Na using inductively coupled plasma optical emission spectrometry. In addition, water soluble F(-) has been measured by ion chromatography. The Be air concentrations in the inhalable, thoracic and respirable aerosol fractions have been calculated. The Be concentrations in the inhalable aerosol fraction vary between the different smelters. The highest GM concentration of Be in the inhalable fraction (122 ng m(-3), n = 30) was measured in the prebake pot room of a smelter using predominantly Jamaican alumina where also the highest individual air concentration of 270 ng m(-3) of Be was identified. The relative distribution of Be in the different aerosol fractions was fairly constant with the mean Be amount for the two sampling campaigns between 44-49% in the thoracic fraction expressed as % of the inhalable amount. Linear regression analysis shows a high correlation between water soluble Be, Al, F and Na describing an average measured chemical bulk composition of the water soluble thoracic fraction as Na(5.7)Al(3.1)F(18). Be is likely to be present as traces in this particulate matter by replacing Al atoms in the condensed fluorides and/or as a major element in a nanoparticle sized fluoride. Thus, the major amount of Be present in the work room atmosphere of Al smelter pot rooms will predominantly be present in combination with substantial amounts of water soluble Al, F and Na. 相似文献
365.
A database of global agricultural primary production has been constructed and used to estimate its energy content. The portion
of crops available for food and biofuel after postharvest losses was evaluated. The basic conditions for agriculture and plant
growth were studied, to ensure sustainable scenarios regarding use of residues. The available energy contents for the world
and EU27 was found to be 7,200–9,300 and 430 TWh, respectively, to be compared with food requirements of 7,100 and 530 TWh.
Clearly, very little, or nothing, remains for biofuel from agricultural primary crops. However, by using residues and bioorganic
waste, it was found that biofuel production could theoretically replace one-fourth of the global consumption of fossil fuels
for transport. The expansion potential for global agriculture is limited by availability of land, water, and energy. A future
decrease in supply of fossil energy and ongoing land degradation will thus cause difficulties for increased biofuel production
from agriculture. 相似文献
366.
Lars Olof Nord Rahul Anantharaman Olav Bolland 《International Journal of Greenhouse Gas Control》2009,3(4):385-392
In this study, a cycle designed for capturing the greenhouse gas CO2 in a natural gas combined cycle power plant has been analyzed. The process is a pre-combustion CO2 capture cycle utilizing reforming of natural gas and removal of the carbon in the fuel prior to combustion in the gas turbine. The power cycle consists of a H2-fired gas turbine and a triple pressure steam cycle. Nitrogen is used as fuel diluent and steam is injected into the flame for additional NOx control. The heat recovery steam generator includes pre-heating for the various process streams. The pre-combustion cycle consists of an air-blown auto-thermal reformer, water–gas shift reactors, an amine absorption system to separate out the CO2, as well as a CO2 compression block. Included in the thermodynamic analysis are design calculations, as well as steady-state off-design calculations. Even though the aim is to operate a plant, as the one in this study, at full load there is also a need to be able to operate at part load, meaning off-design analysis is important. A reference case which excludes the pre-combustion cycle and only consists of the power cycle without CO2 capture was analyzed at both design and off-design conditions for comparison. A high degree of process integration is present in the cycle studied. This can be advantageous from an efficiency stand-point but the complexity of the plant increases. The part load calculations is one way of investigating how flexible the plant is to off-design conditions. In the analysis performed, part load behavior is rather good with efficiency reductions from base load operation comparable to the reference combined cycle plant. 相似文献
367.
Lars C. Larsen Kim C. Zambrano Helle Christiansen Almut Köhler Ulrich Karlson Stefan Trapp 《Environmental Sciences Europe》2001,13(4):227-236
In Axelved, Denmark, an abandoned gas filling station serves as a test field for phytoremediation. Laboratory studies accompany the project. The toxicity of fresh and weathered gasoline and diesel to willow and poplar trees was studied by use of a tree transpiration toxicity test. The correlation between diesel content in soil and decrease in willow tree transpiration (Salix viminalis x schwerinii) was highly significant (r 2=0.81, n=19). the EC50 (50% inhibition of transpiration) for the sum of hydrocarbons (HC) was determined to be 3910 mg/kg (95% confidence interval from 2900 to 5270 mg/kg). The EC10 was 810 mg/kg (95% confidence interval 396 to 1660 mg/kg). The results were verified with artificially mixed diesel and gasolinecontaminated soils and two willow and one poplar species (S. viminalis, S. alba andPopulus nigra). The degradation of radiolabeledm-xylene was studied with and without willows. The compound was readily degraded. Willow trees accelerated the elimination, but mainly due to the volatilization ofm-xylene. Model studies provided the result that biodegradation in soil is the fastest elimination process at the site, but it is limited by the availability of electron acceptors. The pollutants are almost persistent in the groundwater, but in aerated soil, 10000 mg/kg hydrocarbons at 1 m depth are degraded within 13 years. The main effect of willows on the pollutants’ persistence is that willows transpire water, lower the groundwater level and aerate the soil, hereby speeding up biodegradation. 相似文献
368.
Trukhin A Kruchkov F Hansen LK Kallenborn R Kiprianova A Nikiforov V 《Chemosphere》2007,67(9):1695-1700
The primary goal for the study presented here was the preparation and characterisation of enantiomeric pure chlorobornane standards (Toxaphene). In this context, we partially modeled the procedure for Polychloropinene production in the former USSR. The initial reaction was ionic addition of hydrogen chloride to (1S)-alpha-pinene resulting predominantly in (1S)-2-endo-chlorobornane. Further photochlorination gave mixtures of chlorinated terpenes with different average content of Cl per molecule. The resulting mixtures were separated on a silica-gel column and a number of known hepta to decachlorobornanes were identified in fractions with the help of NMR and GC (using electron capture and mass spectrometric detection)--but in very unusual ratios as compared to the technical Toxaphene mixture formerly produced by Hercules (USA). Also several previously unknown congeners were isolated or detected. Three of the isolated congeners were obtained in crystalline state and X-ray crystallography showed their enantiomeric purity. 相似文献
369.
In Sweden the main exposure route for persistent organochlorine pollutants (POP) is through consumption of fatty fish from the Baltic Sea (off the eastern coast). The present study aimed to investigate whether intrauterine exposure for POP may have negative impact on children's weight and height at 4 and 7 years of age, respectively. The study included 174 fishermen's wives from the Swedish east coast who had given birth to an infant with either low (n=55) or normal (n=119) birth weight, and 88 and 206 corresponding women from the Swedish west coast (where the fish is less polluted). Comparisons between the east and west coast cohorts were performed. In addition, blood samples were collected among the east coast women and the concentrations of 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) in plasma was analyzed and estimated for the year of childbirth. There were no significant differences between the east and west coast cohorts regarding weight and height at 4 and 7 years of age. There were, however, significant negative associations between the estimated plasma concentrations of CB-153 during year of childbirth and weight at 4 and 7 years of age, respectively, among the normal birth weight children. The study gives only very weak support for the hypothesized association. 相似文献
370.