Corporate image, European Emission Trading System and Environmental
Regulations, encourage pulp industry to reduce carbon dioxide
(CO2) emissions. Kraft pulp mills produce
CO2 mainly in combustion processes. The largest sources
are the recovery boiler, the biomass boiler, and the lime kiln. Due to utilizing
mostly biomass-based fuels, the CO2 is largely biogenic.
Capture and storage of CO2 (CCS) could offer pulp and paper
industry the possibility to act as site for negative CO2
emissions. In addition, captured biogenic CO2 can be used as
a raw material for bioproducts. Possibilities for CO2
utilization include tall oil manufacturing, lignin extraction, and production of
precipitated calcium carbonate (PCC), depending on local conditions and
mill-specific details. In this study, total biomass-based CO2
capture and storage potential (BECCS) and potential to implement capture and
utilization of biomass-based CO2 (BECCU) in kraft pulp mills
were estimated by analyzing the impacts of the processes on the operation of two
modern reference mills, a Nordic softwood kraft pulp mill with integrated paper
production and a Southern eucalyptus kraft pulp mill. CO2
capture is energy-intensive, and thus the effects on the energy balances of the
mills were estimated. When papermaking is integrated in the mill operations, energy
adequacy can be a limiting factor for carbon capture implementation. Global carbon
capture potential was estimated based on pulp production data. Kraft pulp mills have
notable CO2 capture potential, while the on-site utilization
potential using currently available technologies is lower. The future of these
processes depends on technology development, desire to reuse
CO2, and prospective changes in legislation.
Variability in flower colour of animal-pollinated plants is common and caused, inter alia, by inter-individual differences in pigment concentrations. If and how pollinators, especially bees, respond to these small differences in pigment concentration is not known, but it is likely that flower colour variability impacts the choice behaviour of all flower visitors that exhibit innate and learned colour preferences. In behavioural experiments, we simulated varying pigment concentrations and studied its impact on the colour choices of bumblebees and honeybees. Individual bees were trained to artificial flowers having a specific concentration of a pigment, i.e. Acridine Orange or Aniline Blue, and then given the simultaneous choice between three test colours including the training colour, one colour of lower and one colour of higher pigment concentration. For each pigment, two set-ups were provided, covering the range of low to middle and the range of middle to high pigment concentrations. Despite the small bee-subjective perceptual contrasts between the tested stimuli and regardless of training towards medium concentrations, bees preferred neither the training stimuli nor the stimuli offering the highest pigment concentration but more often chose those stimuli offering the highest spectral purity and the highest chromatic contrast against the background. Overall, this study suggests that bees choose an intermediate pigment concentration due to its optimal conspicuousness. It is concluded that the spontaneous preferences of bees for flower colours of high spectral purity might exert selective pressure on the evolution of floral colours and of flower pigmentation. 相似文献
Recent molecular data on the maternally inherited mitochondrial (mt) DNA have challenged the traditional view that the now
extinct Baltic sturgeon population belonged to the European sturgeon Acipenser sturio. Instead, there is evidence that American sea sturgeon Acipenser oxyrinchus historically immigrated into the Baltic Sea. In this study, we test the hypothesis that A. oxyrinchus introgressed into, rather than replaced, the A. sturio population in the Baltic. We established four single nucleotide polymorphisms (SNPs) in the nuclear MHC II antigen gene with
a species-specific SNP pattern. Using an ancient DNA approach and two independent lines of molecular evidence (sequencing
of allele-specific clones, SNaPshot), we detected both A. sturio and A. oxyrinchus alleles in the available museum material of the now extinct Baltic sturgeon population. The hybrid nature of the Baltic population
was further confirmed by very high levels of heterozygosity. It had been previously postulated that the immigration of the
cold-adapted A. oxyrinchus into the Baltic occurred during the Medieval Little Ice Age, when temperature likely dropped below the degree inducing spawning
in A. sturio. Under this scenario, our new findings suggest that the genetic mosaic pattern in the Baltic sturgeon population (oxyrinchus mtDNA, sturio and oxyrinchus MHC alleles) is possibly caused by sex-biased introgression where spawning was largely restricted to immigrating American
females, while fertilization was predominantly achieved by abundant local European males. The hybrid nature of the former
Baltic sturgeon population should be taken into account in the current reintroduction measures.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
Males often face strong mating competition by neighboring males in their social environment. A recent study by Plath et al.
(Anim Behav 75:21–29, 2008a) has demonstrated that the visual presence of a male competitor (i.e., an audience male) affects
the expression of male mating preferences in a poeciliid fish (Poecilia mexicana) with a weaker expression of mating preferences when an audience male observed the focal male. This may be a tactic to reduce
sperm competition, since surrounding males likely share intrinsic preferences for female traits or copy mate choice decisions.
Here, we examined the hypothesis that a same-sex audience would affect female mate preferences less than male mating preferences. Our hypothesis was based on the assumptions that (1) competition for
mates in a fashion that would be comparable in strength to sperm competition or overt male–male aggression is absent among
Poecilia females, and (2) P. mexicana females typically form female-biased shoals, such that almost any female mate choice in nature occurs in front of a female
audience. Poecilia females (P. mexicana, surface and cave form, and the closely related gynogenetic Poecilia formosa) were given a choice between a large and a small male, and the tests were repeated while a conspecific, a heterospecific,
or no audience female (control) was presented. Females spent more time in the neutral zone and, thus, less time near the males
during the second part of a trial when an audience was presented, but—consistent with predictions—females showed only slightly
weaker expression of mate preferences during the second part of the tests. This decline was not specific to the treatment
involving an audience and was significantly weaker than the effect seen in the male sex. 相似文献
Environment Systems and Decisions - Organizational and technical approaches have proven successful in increasing the performance and preventing risks at socio-technical systems at all scales.... 相似文献
Outdoor recreation and nature-based tourism represent an increasingly intensive form of land use that has considerable impacts
on native ecosystems. The aim of this paper is to investigate how revegetation and management of ski runs influence soil nutrients,
vegetation characteristics, and the possible invasion of nonnative plant species used in revegetation into native ecosystems.
A soil and vegetation survey at ski runs and nearby forests, and a factorial experiment simulating ski run construction and
management (factors: soil removal, fertilization, and seed sowing) were conducted at Ruka ski resort, in northern Finland,
during 2003–2008. According to the survey, management practices had caused considerable changes in the vegetation structure
and increased soil nutrient concentrations, pH, and conductivity on the ski runs relative to nearby forests. Seed mixture
species sown during the revegetation of ski runs had not spread to adjacent forests. The experimental study showed that the
germination of seed mixture species was favored by treatments simulating the management of ski runs, but none of them could
eventually establish in the study forest. As nutrient leaching causes both environmental deterioration and changes in vegetation
structure, it may eventually pose a greater environmental risk than the spread of seed mixture species alone. Machine grading
and fertilization, which have the most drastic effects on soils and vegetation, should, therefore, be minimized when constructing
and managing ski runs. 相似文献
Summary Solitary and social nests of the facultatively social carpenter bee Xyclopa pubescens can be found simultaneously during the major part of the breeding season. Social nests contain a reproductively dominant forager and either her adult offspring or a formerly reproductive, guarding female. The costs and benefits to the dominant animal of allowing a defeated female to remain as a guard in the nest were analysed in terms of brood loss and brood gain. The costs included the probability that the guard would regain reproductively dominant status. The most important benefits were the protection that a guard provided against pollen robbery by conspecifics and the longer foraging time available to a forager when her nest was protected. The balance between costs and benefits depended on the severity of ecological constraints. During certain periods of intense competition for pollen or nests, the benefits clearly outweighed the costs.Correspondence to: K. Hogendoorn 相似文献