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1.
Alexei V. Uvarov 《Environmental monitoring and assessment》2000,60(3):337-357
Long-term charcoal production in small private charcoal kilns (CK) in Eastern Bieszczady Mts. (SE Poland) can cause local smoke contamination of the ambient forest environment. Responses of model soil systems, contaminated or not contaminated by CK smoke, to contrasting combinations of hydrothermic regimes were compared in laboratory microcosms (respiration of soil community, decomposition rate of soil organic matter and cotton stripes, herb seeds germination were studied). The majority of the obtained data show a markedly higher level of soil biological activity in the CK versus the control series. In some cases CK and control soil systems show different patterns of reactions to the tested combinations of microclimate regime. These phenomena should at least partly be attributed to the effects of CK pollution. 相似文献
2.
The euphausiids Thysanoessa inermis (Kroyer 1846), Thysanoessa spinifera (Holmes 1900), and Euphausia pacifica (Hansen 1911) are key pelagic grazers and also important prey for many commercial fish species in the Gulf of Alaska (GOA).
To understand the role of the euphausiids in material flows in this ecosystem their growth rates were examined using the instantaneous
growth rate (IGR) technique on the northern GOA shelf from March through October in 2001–2004. The highest mean molting increments
(over 5% of uropod length increase per molt) were observed during the phytoplankton bloom on the inner shelf in late spring
for coastal T. inermis, and on the outer shelf in summer for T. spinifera and more oceanic E. pacifica, suggesting tight coupling with food availability. The molting rates were higher in summer and lower in spring, for all species
and were strongly influenced by temperature. Mean inter-molt periods calculated from the molting rates, ranged from 11 days
at 5°C to 6 days at 8°C, and were in agreement with those measured directly during long-term laboratory incubations. Growth
rate estimates depended on euphausiid size, and were close to 0 in early spring, reaching maximum values in May (0.123 mm day−1 or 0.023 day−1 for T. inermis) and July (0.091 mm day−1 or 0.031 day−1 for T. spinifera). The growth rates for E. pacifica remained below 0.07 mm day−1 (0.016 day−1) throughout the season. The relationship between T. inermis weight specific growth rate (adjusted to 5°C) and ambient chlorophyll-a concentration fit a Michaelis–Menten curve (r
2 = 0.48) with food saturated growth rate of 0.032 day−1 with half saturation occurring at 1.65 mg chl-a m−3, but such relationships were not significant for T. spinifera or E. pacifica. 相似文献
3.
Accumulation features of persistent organochlorines in resident and migratory birds from Asia 总被引:1,自引:0,他引:1
Kunisue T Watanabe M Subramanian A Sethuraman A Titenko AM Qui V Prudente M Tanabe S 《Environmental pollution (Barking, Essex : 1987)》2003,125(2):157-172
Concentrations of organochlorine contaminants including polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), chlordane compounds (CHLs), hexachlorobenzene (HCB) were determined in the resident and migratory birds, which were collected from India, Japan, Philippines, Russia (Lake Baikal) and Vietnam. Accumulation patterns of organochlorine concentrations in resident birds suggested that the predominant contaminants of each country were as follows: Japan--PCBs Philippines--PCBs and CHLs, India--HCHs and DDTs, Vietnam--DDTs, and Lake Baikal--PCBs and DDTs. The migratory birds from Philippines and Vietnam retained mostly the highest concentrations of DDTs among the organochlorines analyzed, indicating the presence of stopover and breeding grounds of those birds in China and Russia. On the other hand, migratory birds from India and Lake Baikal showed different patterns of organochlorine residues, reflecting that each species has inherent migratory routes and thus has exposure to different contaminants. Species which have breeding grounds around the Red Sea and Persian Gulf showed high levels of PCBs, indicating the presence of areas heavily polluted by PCBs in the Middle East. 相似文献
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5.
Das K Holsbeek L Browning J Siebert U Birkun A Bouquegneau JM 《Environmental pollution (Barking, Essex : 1987)》2004,131(2):197-204
Stable carbon and nitrogen isotopes (delta13C and delta15N) and trace metals (Cd, Zn, Cu, Fe, Se, and Hg) were analysed in the tissues of 46 harbour porpoises (Phocoena phocoena relicta) caught in fishing nets along the Ukrainian coasts between 1997 and 1998. Mean delta13C values differed significantly between male and female harbour porpoises suggesting a trophic segregation between sexes with a more coastal distribution for females at least during their gestation and nursing periods. Hepatic Hg was correlated to delta13C measurements, reflecting a different exposure linked to coastal vs offshore feeding habitats. A geographical comparison with existing data from other regions showed general low levels of Hg, Cd, Cu and Zn in the tissues of harbour porpoises from the Black Sea compared to other Atlantic and North Sea areas. 相似文献
6.
We study how the combination of tides and freshwater buoyancy affects the marine organisms accumulation and horizontal transport
in the ROFI system of the eastern English Channel. The Princeton Ocean Model coupled with a particle-tracking module is used
to study the migration of fish eggs and larvae under different forcing conditions. Results of modeling are validated against
observed concentrations of Flounder (Pleuronectes flesus) larvae. Numerical Lagrangian tracking experiments are performed with passive and active particles, representing sea-water
organisms. Passive particles are neutrally buoyant whereas active particles are able to exercise light dependent vertical
migrations equating to the swimming behavior of larvae. The experiments reveal that the strongest accumulation of particles
occurs along the French coast on the margin of the ROFI. This happens because the interaction between the turbulence, the
freshwater buoyancy input, and tidal dynamics, produces particle trapping and vertical spreading within the frontal convergence
zone. Tides and freshwater input induce net alongshore horizontal transport toward the North. Tidal currents modulate the
magnitude of horizontal transport whereas the fresh water input controls more the location of accumulation zones. Tracking
experiments with active particles indicate that the vertical migration leads to a significant departure from the passive particle
transport pattern. Differences lie in the shape of the particle transport pattern and the rate of the northward migration.
In particular, vertically migrating particles travel slower. To find possible Flounder migration pathways, particles are released
within the assumed spawning area of Flounder. The model predicts larvae drift routes and demonstrates that throughout the
entire particle-tracking period the horizontal structure of the particle distribution is consistent with the larvae concentrations
observed during the field experiments. 相似文献
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8.
City action is critical to achieving global visions for sustainability such as the UN’s Sustainable Development Goals (SDGs). However, SDG ‘localisation’ is complex procedure, with divergent outcomes depending on context and diverse city processes. This paper considers the operational challenges faced by city actors in taking on the SDGs, and subsequent implications for initiating local (and global) sustainability transitions. We analyse emergent approaches to SDG localisation within the Asia–Pacific, using a policy analysis framework (transition management) to assess transformation potential. We find that SDG localisation can influence urban sustainability, but effective implementation requires sufficient data, resourcing, and guidance—which are not readily, nor equally available to all city governments. City-to-city peer learning can accelerate SDG uptake, but realising the transformative ambition set out by the SDGs will require an approach to localisation that clearly demonstrates why and how any city government can and should engage with global sustainability frameworks. 相似文献
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10.
Martin Brokate Stephen MacCarthy Alexander Pimenov Alexei Pokrovskii Dmitrii Rachinskii 《Environmental Modeling and Assessment》2011,16(4):313-333
Cyclic wetting and drying of soils due to changing weather conditions is characterised by a well-documented hysteresis in
the relationship between the pressure or matric potential and the water content in the soil. Hysteresis manifests itself through
a difference in drying and wetting curves. Its presence suggests that there is dissipation of energy associated with intermittent
wetting and drying of the soil, which can be released in the form of heat. In this paper, we discuss a model for evaluation
of the energy dissipation rate due to soil-moisture hysteresis. The model has three main ingredients: (a) a hysteresis constitutive
relationship between soil-water potential and moisture content in the soil, which is modelled by the Preisach operator; (b)
a lumped form of Darcy’s law assuming that the water flux is proportional to the difference of potentials in the soil and
on its surface; (c) a rainfall term governing the evolution of the outer potential, which is modelled by a periodic forcing
or a Poisson process. We propose a combination of analytic and numerical methods to evaluate the energy dissipation rate and
how it is affected by the variation of rain parameters, such as the frequency of arrivals of rain cells and their shape, intensity
and duration. 相似文献