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301.
We summarize the latest results on the rapid changes that are occurring to Arctic sea ice thickness and extent, the reasons
for them, and the methods being used to monitor the changing ice thickness. Arctic sea ice extent had been shrinking at a
relatively modest rate of 3–4% per decade (annually averaged) but after 1996 this speeded up to 10% per decade and in summer
2007 there was a massive collapse of ice extent to a new record minimum of only 4.1 million km2. Thickness has been falling at a more rapid rate (43% in the 25 years from the early 1970s to late 1990s) with a specially
rapid loss of mass from pressure ridges. The summer 2007 event may have arisen from an interaction between the long-term retreat
and more rapid thinning rates. We review thickness monitoring techniques that show the greatest promise on different spatial
and temporal scales, and for different purposes. We show results from some recent work from submarines, and speculate that
the trends towards retreat and thinning will inevitably lead to an eventual loss of all ice in summer, which can be described
as a ‘tipping point’ in that the former situation, of an Arctic covered with mainly multi-year ice, cannot be retrieved. 相似文献
302.
Katrin Quiel Annette Becker Volker Kirchesch Andreas Schöl Helmut Fischer 《Regional Environmental Change》2011,11(2):405-421
The effects of changing climatic and socioeconomic conditions on the water quality of the Elbe River were investigated using
the deterministic model QSim. Since the impact of global change on river water quality marks the endpoint of various processes
in the catchment and in the atmosphere, this study was performed within a network of interacting models that determined input
parameters for water quality simulations. The development of phytoplankton and nutrient concentrations under conditions of
global change was modeled along a 700 km stretch of the river. The simulations revealed a strong, scale-dependent effect of
climate change on phytoplankton biomass, leading to a longitudinal shift of the dominating processes (primary productivity
vs. respiration) along the river continuum. Under reduced flow, combined with increasing temperature and global radiation,
phytoplankton biomass increased and phytoplankton maxima shifted in upstream direction, followed by higher system respiration
rates in the adjacent downstream sections. In contrast, higher flow shifted the phytoplankton maximum toward the downstream
sections. Even a drastic reduction of phosphorus inputs from anthropogenic sources had only limited influence on algal biomass,
due to the ability of algal cells to store phosphorus. A strong reduction in P-inputs especially in the headwaters would be
necessary to counterbalance the possible climate-induced effects on algal biomass. 相似文献
303.
Reyhan Akçaalan Meric Albay Latife Koker Julia Baudart Delphine Guillebault Sabine Fischer Wilfried Weigel Linda K. Medlin 《Environmental monitoring and assessment》2018,190(1):42
Monitoring drinking water quality is an important public health issue. Two objectives from the 4 years, six nations, EU Project μAqua were to develop hierarchically specific probes to detect and quantify pathogens in drinking water using a PCR-free microarray platform and to design a standardised water sampling program from different sources in Europe to obtain sufficient material for downstream analysis. Our phylochip contains barcodes (probes) that specifically identify freshwater pathogens that are human health risks in a taxonomic hierarchical fashion such that if species is present, the entire taxonomic hierarchy (genus, family, order, phylum, kingdom) leading to it must also be present, which avoids false positives. Molecular tools are more rapid, accurate and reliable than traditional methods, which means faster mitigation strategies with less harm to humans and the community. We present microarray results for the presence of freshwater pathogens from a Turkish lake used drinking water and inferred cyanobacterial cell equivalents from samples concentrated from 40 into 1 L in 45 min using hollow fibre filters. In two companion studies from the same samples, cyanobacterial toxins were analysed using chemical methods and those dates with highest toxin values also had highest cell equivalents as inferred from this microarray study. 相似文献
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The charcoal kilns under study were situated in the Polish Western Carpathiens (Bieszczady). Aromatic hydrocarbon products of wood burning in the kilns were identified. The rate of decomposition of beech leaves was relatively high as environmental conditions enhanced decomposition. The intensity of soil metabolism is increasing during a long-term exposure to smoke, which is one of the indicators of anthropogenic disturbance resulting from organic factors. 相似文献
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