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By means of environ analysis the four-compartment model of matter cycle through the ecosystem of a mesotrophic bog is investigated. The aggregated compartments are: plants, animals, fungi combined with bacteria, and litter. The model is based on data obtained by observations and estimations made on the experimental area of “Tajozhny Log” ocated in the southern taiga sub-zone. Environ analysis enables one to set up, in the quantitative form, certain conclusions on the relative importance of individual system components and diverse processes in the matter cycle, as well as to obtain a number of quantitative characteristics of the turnover. Environ analysis is discussed as a preliminary stage in developing more complex, dynamic models of the matter cycle. 相似文献
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The observed growth of a particular forest stand can be described by many models and explained by some of them. The forest growth models are also successfully applied for extrapolating the growth curve. However, the known models of forest growth are not “one-point” models. They are not designed to predict the future growth of a forest stand from its current state: the model parameters either are not directly measurable or cannot be measured with relevant accuracy. This article is an attempt to use Jørgensen–Svirezhev theory as a new clue to the choice of variables that determines forest growth. The postulates of this theory combined with the pipe theory of tree growth lead to conclusion that biomass of a stand should be proportional to the four-fifths power of its age. Empirical validation, however, disclosed that calendar age is rather approximate measure of ecosystem ontogeny. Delayed development or intensive thinning of a forest stand at the early stages leads to rejuvenation bias. Thus derived 4/5-law model approximates well-known Chapman–Richards model in the neighborhood of the inflection point, and is applicable to middle-aged forest stands. 相似文献
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Mihaela Laurenta Alexandrov Jürg Bloesch 《Environmental science and pollution research international》2009,16(Z1):42-45
Lake Tasaul on the Black Sea coast is highly eutrophic, but not strongly contaminated (heavy metals, PAHs, and organochlorine
pesticides). Cyanophytes dominate phytoplankton by 67–94% and form frequent algal blooms. High primary production (up to 270 mg
Cass/m2.h) and algal biomass (maximum chlorophyll a concentration 417 μg/l) may be controlled by light, as Secchi depth is often below 1 m. The main tributary, Casimcea River,
provides high quantities of suspended matter and about 3 tons TP/year and 660 tons TN/year. Based on chemical and biological
analysis as well as fishery investigations, we provide recommendations for Lake Tasaul rehabilitation. 相似文献
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Modelling of matter cycle in a mesotrophic bog ecosystem II. Dynamic model and ecological succession
Based upon the the results of static environ analysis of the organic matter cycle through the ecosystem, a number of dynamic models are developed, in this second part, for the matter and nitrogen cycles. Probable outcomes of ecological succession are obtained within the framework of the dynamic model without using the ergodic hypothesis that is implicitly adopted in ecological studies. The dynamics of both stocks in the ecosytem components and flows among them can be observed within the model in order to compare some turnover characteristics of the succession series with those of the ecological one. 相似文献
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V. Alexandrov A. Sameh Y. Siddique Z. Zlatev 《Environmental Modeling and Assessment》1997,2(4):365-377
The numerical treatment of a regional air pollution model (such models are, as a rule, described mathematically by systems of partial differential equations) leads to the solution of very large computational problems. The chemical submodel of an air pollution model is normally the most timeconsuming part of the computational work. The application of appropriate discretization and splitting procedures reduces the chemical submodel to a large number of relatively small ODE systems (one such system per gridpoint). In the process of searching for efficient numerical algorithms for the chemical submodels one can carry out experiments by using only one such ODE system in order to facilitate the work. This approach has been used in connection with a particular chemical scheme, the condensed CBM IV scheme, which is used in several large air pollution models. Six integration algorithms have been tested on a set of typical scenarios (consisting of different starting concentrations and/or of different values of the emissions). The advantages and the disadvantages of the algorithms tested are discussed. The final decision about the most efficient algorithm, among the algorithms tested, should be made after a second series of experiments. The coupling of the chemical process with the transport of air pollution (on, at least, a twodimensional domain) together with the application of highspeed computers has to be studied in the second series of experiments, which will be performed in a subsequent paper. 相似文献
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Bidar G Pruvot C Garçon G Verdin A Shirali P Douay F 《Environmental science and pollution research international》2009,16(1):42-53
Background, aim, and scope The reclamation of nonferrous metal-polluted soil by phytoremediation requires an overall and permanent plant cover. To select
the most suitable plant species, it is necessary to study metal effects on plants over the time, thereby checking that metals
remain stored in root systems and not transferred to aerial parts. In this purpose, the seasonal and annual variations of
metal bioaccumulation, transfer, and phytotoxicity in Trifolium repens and Lolium perenne grown in a Cd-, Pb-, and Zn-contaminated soil were also studied.
Materials and methods The experimental site was located near a closed smelter. In spring 2004, two areas were sown with T. repens and L. perenne, respectively. Thereafter, the samplings of plant roots and shoots and surrounding soils were realized in autumn 2004 and
spring and autumn 2005. The soil agronomic characteristics, the Cd, Pb, and Zn concentrations in the surrounded soils and
plant organs, as well as the oxidative alterations (superoxide dismutase [SOD], malondialdehyde [MDA], and 8-hydroxy-2′-deoxyguanosine
[8-OHdG]) in plant organs were carried out.
Results Whatever the sampling period, metal concentrations in soils and plants were higher than background values. Contrary to the
soils, the fluctuations of metal concentrations were observed in plant organs over the time. Bioaccumulation and transfer
factors confirmed that metals were preferentially accumulated in the roots as follows: Cd>Zn>Pb, and their transfer to shoots
was limited. Foliar metal deposition was also observed. The results showed that there were seasonal and annual variations
of metal accumulation in the two studied plant species. These variations differed according to the organs and followed nearly
the same pattern for the two species. Oxidative alterations were observed in plant organs with regard to SOD antioxidant activities,
MDA, and 8-OHdG concentrations. These alterations vary according to the temporal variations of metal concentrations.
Discussion Metal concentrations in surrounded soils and plant organs showed the effective contamination by industrial dust emissions.
Metals absorbed by plants were mainly stored in the roots. With regard to this storage, the plants seemed to limit the metal
transfer to their aerial parts over the time, thereby indicating their availability for metal phytostabilization. Aerial deposition
was another source of plant exposure to nonferrous metals. Despite the occurrence of metal-induced oxidative alterations in
plant organs, both plant species seemed to tolerate a high metal concentration in soils.
Conclusions Taken together, these results indicated that T. repens and L. perenne were able to form a plant cover on highly Cd-, Pb-, and Zn-polluted soils, to limit the metal transfer to their aerial parts
and were relatively metal-tolerant. All these characteristics made them suitable for phytostabilization on metal-contaminated
soils. These findings also highlighted the necessity to take into account seasonal and annual variations for a future phytomanagement.
Recommendations and perspectives In this work, the behavior of plant species grown in metal-polluted soil has been studied during 2 years. Obviously, this
time is too short to ensure that metals remain accumulated in the root system and few are transferred in aerial parts over
the time. It is why regular monitoring should be achieved during more than a decade after the settlement of the plant cover.
This work will be completed by the study of the T. repens and L. perenne effects on mobility of metals in order to evaluate the quantities of pollutants which could be absorbed by the biota and
transferred to groundwater. Bioaccessibility tests could be also realized on polluted soils in order to evaluate the phytostabilization
impacts on the exposition risks for humans. 相似文献
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Michael Obersteiner G. Alexandrov Pablo C. Benítez Ian McCallum Florian Kraxner Keywan Riahi Dmitry Rokityanskiy Yoshiki Yamagata 《Mitigation and Adaptation Strategies for Global Change》2006,11(5-6):1003-1021
In this paper we provide an analytical framework to estimate the joint production of biomass and carbon sequestration from afforestation and reforestation activities. The analysis is based on geographical explicit information on a half-degree resolution. For each grid-cell the model estimates forest growth using a global vegetation model and chooses forest management rules. Land prices, cost of forest production and harvesting are determined as a function of grid specific site productivity, population density and estimates of economic wealth. The sensitivity of the results due to scenario storylines is assessed using different population and economic growth assumptions, which are consistent with B1 and A2 of the Intergovernmental Panel on Climate Change Special Report on Emission Scenarios (IPCC-SRES) marker scenarios. Considerable differences in the economic supply schedules are found. However, technical potentials seem to converge given constancy in other underlying assumptions of the model. 相似文献
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R. Djingova I. Kuleff S. Arpadjan S. Alexandrov A. Voulgaropoulos T. Sawidis 《毒物与环境化学》2013,95(3):149-158
NAA and AAS have been applied to determine the content of As, Br, Ca, Cd, Co, Cr, Cu, Fe, K, La, Mn, Na, Ni, Pb, Sb, Sc, Sm and Zn in Ulva lactuca and Gracilaria verrucosa from Thermaikos Gulf, Greece. The analytical data has been subjected to cluster and stepwise discriminant analysis. Thus the influence of some industrial sources on the pollution of water in the Gulf is detected and correlation between Zn‐Co‐Cr‐La; Br‐K; Cu‐Ni; Cd‐Sb‐Mn in the investigated algae is established. 相似文献
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