منابع مشابه
Bringing new life to the dead zone.
The Gulf of Mexico “dead zone” reached a record 7,700 square miles in the summer of 1999. That year, heavier flow in the Mississippi River brought an abundance of nutrients to the Gulf, resulting in hypoxia, or inadequate dissolved oxygen in bottom waters that forces bottom-dwelling animals to either flee or die. With the year 2001 have come legislative efforts to reduce the dead zone—if not ki...
متن کاملThe end-Permian extinction
The end Permian extinction was the greatest mass extinction of the Phanerozoic Era. It impacted marine and terrestrial plants and animals. Although the rate of the extinction has been controversial in the past, recent evidence suggests that the extinction progressed in two pulses approximately 5-12 million years apart. The second pulse of the extinction is marked by a sharp temperature spike an...
متن کاملInvestigation of purge time in cathodic dead-end mode PEMFC
Recently, special type of fuel cells has been developed that operates in a Dead End mode. Working in this condition, the Dead-End fuel cell is supplied withhydrogen almost at the same rate of consumption. It is noteworthy to mention thatall of the water transport mechanisms have been considered in this simulation.Water accumulation that is directly proportional to the cell current is of a grea...
متن کاملCalibrating the end-Permian mass extinction.
The end-Permian mass extinction was the most severe biodiversity crisis in Earth history. To better constrain the timing, and ultimately the causes of this event, we collected a suite of geochronologic, isotopic, and biostratigraphic data on several well-preserved sedimentary sections in South China. High-precision U-Pb dating reveals that the extinction peak occurred just before 252.28 ± 0.08 ...
متن کاملGene swapping in the dead zone
Viruses can swap DNA between bacteria that live in regions of the oceans with little or no oxygen.
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ژورنال
عنوان ژورنال: Proceedings of the National Academy of Sciences
سال: 2001
ISSN: 0027-8424,1091-6490
DOI: 10.1073/pnas.131218098