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61.
Large quantities of floating macroalgae are traveling in coastal waters of the SE Pacific and in other temperate climate zones.
While afloat, these algae are potentially exposed to full solar radiation, including UVA and UVB, which can have profound
effects on their physiological and growth performance. Latitudinal variations in UV-radiation (UVR) are hypothesized to affect
floating algae differently with higher impacts at low latitudes than at high latitudes. In addition, UVR together with grazing
might accelerate the demise of floating kelps. This hypothesis was tested with outdoor laboratory experiments in which sporophytes
of the giant kelp Macrocystis pyrifera (L.) C. Agardh were exposed to a combination of different UVR regimes (PAR only, PAR + UV) and grazing at three sites along
the Chilean coast (20°S, 30°S, and 40°S). A latitudinal trend in irradiance was detected with increasing values from 40°S
to 20°S. Surprisingly, floating M. pyrifera responded with a high acclimation potential within this latitudinal UVR gradient. At 20°S, floating kelps were slightly sensitive
to UVR, which was reflected in reduced blade growth. At 30°S, physiological responses were hardly affected by the prevailing
irradiance but sporophyte growth and thus persistence mainly depended on the presence or absence of amphipod grazers. At high
latitudes, grazing had only minor impacts on algal biomass and blade growth, and kelps thrived well under all tested environmental
conditions. Overall, our results reveal that floating M. pyrifera was only slightly affected by UVR and that sporophytes can efficiently acclimate over a latitudinal UVR gradient that spans
from 20°S to 40°S. Given this high acclimation potential, we suggest that these (and possibly other) positively buoyant algae
are important dispersal agents over a wide range of temperate latitude conditions. 相似文献
62.
Stefan Zerbe Peggy Steffenhagen Karsten Parakenings Tiemo Timmermann Annett Frick Jörg Gelbrecht Dominik Zak 《Environmental management》2013,51(6):1194-1209
The restoration of ecosystem services, i.e., production, regulation, and information, is a global challenge, which the federal state of Mecklenburg-Vorpommern in NE Germany addressed in 2000 by rewetting over 20,000 ha of degraded peatlands within the Mire Restoration Program. We evaluated ecosystem services in 23 rewetted sites by assessing the following mire parameters within a ten year period: (a) dominant vegetation at the ecosystem level, (b) peat formation potential at the landscape level, and (c) aboveground biomass and nutrient levels. Seven to 10 years after rewetting, the wetlands formed a mosaic of vegetation types with the highest potential for peat formation and several dominant, peat-forming species accumulated high levels of aboveground biomass and nutrients (C, N, P). Common reed (Phragmites australis) accumulated the most biomass (up to 24 t dry matter/ha), and N+P during the growing season. A future management option is to annually harvest aquatic and wetland plants to reduce nutrient levels in restored mire ecosystems. 相似文献
63.
64.
Urs Baumann Gustav Peter Ernst Pletscher Marcel Wettstein 《Environmental Sciences Europe》2003,15(4):227-233
Before waste-water-relevant organic materials are to be found in large quantities, their specific behavior in sewage treatment plants must be known. With the aid of the OECD simulation test #303 A, an estimation of their elimination in biological clarification stages can be made. In this work, an economical and continuous testing system is presented, which consists of a polyester flies bound to an activated biosludge with a high inoculum density, allowing one to measure no only the elimination of individual substances, but also the specific degree of mineralization. The toxicity of the activated biosludge and the nitrifying substances can also be examined. With the described testing procedure, it is possible to determine the rate of degradation within only a few hours. Finally, it can also be seen that it is possible to reliably and continuously determine the rate of anaerobic, biological degradability through the use of such a modified testing procedure. 相似文献
65.
Juliane Straube Jill Manteufel Janin Heinze Karsten Fehlhaber Uwe Truyen Thiemo Albert 《Food and environmental virology》2010,2(2):74-82
Since highly pathogenic avian influenza virus H5N1 emerged in 1997, avian influenza is considered one of the most important
infectious diseases globally. In respect of virus transmission to humans, the consumption of raw poultry products remains
of serious concern. In this study, data about survival time and inactivation kinetics of two low pathogenic avian influenza
virus (AIV) strains (H3N8, H5N6) in short fermented raw sausage were obtained. In addition, the impact of the preserving factors
d,l-lactic acid and sodium chloride on virus infectivity was evaluated through in vitro studies. Virus infectivity was confirmed
in embryonated chicken eggs. Inactivation of H3N8 was seen in d,l-lactic acid solutions (0.15 and 0.20%, pH 4.40–4.70 and pH 3.80–3.91) at both temperatures (20 vs. 4°C) during 3 days of
exposure. However, infectious virus particles could still be detected after exposure to 0.1% d,l-lactic acid (pH 5.80–5.99). In all NaCl solutions (2, 6 and 12% w/v), infectivity of the H3N8 strain decreased steadily but
reduction of the virus titre increased significantly with higher temperature. In raw sausages, decline in virus titre was
observed for both strains during ripening and storage. Thereby, decline of virus infectivity was dependent on time and temperature
with a more marked effect at higher temperatures (22 vs. 7°C). At refrigeration (7°C), both viruses maintained infectivity
over 14 days. Results indicate that appropriate processing of short fermented raw poultry sausage is likely to reduce risk
of virus exposure due to adequate inactivation of AIV during ripening and storage. 相似文献
66.
67.
ABSTRACTLand-use decisions can change abruptly in response to shocks, and warfare and armed conflicts are among the most drastic and globally frequent shocks. Yet, our understanding of where armed conflict affects land systems, how land-use patterns are impacted, and how far-reaching and persistent these changes are, is partial. We used a spatially detailed dataset on armed conflict and a literature review to explore these questions. A number of key insights emerged from our study: (1) warfare and armed conflict affect land systems mainly in more densely populated areas, regardless of the dominating land use; (2) warfare and armed conflict can impact land systems in major ways, but these effects are diverse and not unidirectional; (3) warfare and armed conflict primarily affects land systems locally, but can forge telecouplings; and (4) although the impact of warfare and armed conflict is often immediate, it can instigate long-lasting land-use legacies. 相似文献
68.
Alla L. Alpatova Melissa J. Baumann Simon H. Davies Susan J. Masten 《Environmental Chemistry Letters》2013,11(3):309-313
This article reports for the first time that fullerene (nC60) can form chlorinated disinfection by-products in aqueous systems at ambient temperature. The ability of nC60 to form colloidal suspensions in aqueous media increases the chance that these particles will migrate in the environment and then in drinking water supply systems. Since nC60 is not completely removed by conventional water treatment, any residual nC60 is likely to be oxidized during disinfection process. While the ozonation of nC60 has been studied, little is known about the reaction between nC60 and chlorine. To address this issue, we subjected aqueous nC60 suspensions to chlorination and sequential ozonation/chlorination at ozone dosages of 4.5, 10, 15 and 24 mg O3/mg nC60. The morphology and physicochemical properties of oxidized nC60 aggregates were evaluated by scanning electron microscopy, transmission electron microscopy, UV–visible absorption spectroscopy and X-ray photoelectron spectroscopy (XPS). We found that while the particles in the as-prepared nC60 were predominantly spheres, the ozonation of nC60 resulted in the formation of irregularly shaped aggregates. The concentration of atomic carbon found by XPS in the nC60 samples decreased from 92 % for the as-prepared nC60 to 50 % for the aggregates ozonated at 24 mg O3/mg nC60 and then chlorinated at 68 mg Cl2/L and allowed to react for 100 min. The presence of Cl atoms covalently bonded to C atoms was confirmed by XPS peaks corresponding to a binding energy (E b) of 200.1–202.4 eV. This demonstrates the need to better assess and monitor the formation of potentially toxic chlorinated disinfection by-products from carbon nanomaterials during water treatment. 相似文献
69.
Jellyfish accumulations are often problematic for tourism and fisheries both along European coastlines and overseas. They damage the reputation of several seaside resorts and cause serious economic losses. On the German Baltic coast, jellyfish accumulations are well known, too. Besides population increase due to anthropogenic effects, normal hydrodynamic processes are notable key factors when it comes to jellyfish accumulations. Along German Baltic coastlines, moon jellyfish (Aurelia aurita) occur most frequently but also stinging lion??s mane jellyfish (Cyanea capillata) appear regularly, however not as abundant. The objectives of our study were a) to screen when, where, how many and which jellyfish species occur on German Baltic coasts, b) to find the causes for jellyfish accumulations and c) to evaluate how beach visitors perceive native medusae and whether information can influence their perception. Different methods where combined: systematic jellyfish observations in cooperation with lifeguards, investigations of jellyfish abundance in shallow water zones, and interviews with beach visitors. Our results suggest that jellyfish occurrence along the German Baltic coast correlates with offshore wind or shore-parallel wind, which cause upwelling events. In contrast, there is no evidence that frequency of jellyfish occurrence was dependent on water temperature in summer. In regard to tourism, we found that beach visitors who received information about jellyfish stated to feel significantly less bothered by medusae. Overall, this article addresses different methods to learn more about jellyfish accumulations and it shows information strategies in terms of improved beach management. 相似文献
70.
Global assessment of the non-equilibrium concept in rangelands 总被引:2,自引:0,他引:2
The non-equilibrium concept of rangeland dynamics predicts that the potential for grazing-induced degradation is low in rangelands with relatively variable precipitation. To date, evidence in support of the non-equilibrium concept has been inconsistent. Using a standardized protocol, including a newly developed global map of rainfall variability, we reviewed the incidence of degradation in relation to rainfall variability across 58 published studies. We distinguished between (1) zonal degradation (i.e., degradation independent of water and key resources), (2) degradation in the presence of key resources, and (3) degradation in the presence of water. For studies not affected by proximity to permanent water or key resources, we found strong support for the non-equilibrium concept for rangelands. Zonal degradation was absent at CV (coefficient of variation) values above 33%, which has been proposed as a critical threshold. Grazing degradation was almost entirely restricted to areas with relatively stable annual precipitation as expressed by a low CV, or to rangelands with key resources or water points nearby. To better understand rangeland dynamics, we recommend that future studies use globally comparable measures of degradation and rainfall variability. Our work underlines that rangelands with relatively stable rainfall patterns, and those with access to water or key resources, are potentially vulnerable to degradation. Grazing management in such areas should incorporate strategic rest periods. Such rest periods effectively mimic natural fluctuations in herbivore populations, which are a defining characteristic of non-degraded rangelands occurring under highly variable precipitation regimes. 相似文献