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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >K-Pg extinction patterns in marine and freshwater environments: The impact winter model
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K-Pg extinction patterns in marine and freshwater environments: The impact winter model

机译：海洋和淡水环境中的K-Pg灭绝模式：冬季影响模型

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The Chicxulub asteroid impact produced massive extinction in terrestrial environments most likely through an intense heat pulse and subsequent widespread fires. Aquatic environments were shielded from this heat and fire but nevertheless showed massive extinction in marine environments and, for reasons unexplained, far less extinction in freshwater environments. Extinction in marine environments resulted from the effects of an "impact winter" caused by dust and smoke in the atmosphere that extinguished sunlight at the Earth's surface for a period of months to years. The resulting cessation of photosynthesis caused a globally extensive extinction of phytoplankton taxa. Because aquatic ecosystems, unlike terrestrial environments, are strongly dependent on daily photosynthetic output by autotrophs, loss of phytoplankton likely caused catastrophic mortality and extinction in aquatic ecosystems. Other potential causes of mortality in aquatic ecosystems include lower ambient temperatures and anoxia due to the lack of photosynthetic oxygen. Inland waters, although probably subject to high mortality, showed lower proportionate extinction than marine environments probably because of the greater potential among the freshwater taxa for dormancy, the greater efficiency of reaeration by rapid flow to offset oxygen demand, abundant thermal refugia fed by groundwater at moderate temperatures, and preadaptation of freshwater taxa to a great degree of environmental variability. In addition, detrital feeders appear to have had low extinction rates in either marine or freshwater environments, but again freshwater taxa would have been favored by higher renewal rates of detrital organic matter as a result of their direct hydrologic contact with soil.
机译：奇克卢布小行星撞击在陆地环境中造成了大规模灭绝，这很可能是由于强烈的热脉冲和随后的大火所致。水生环境不受这种热和火的影响，但在海洋环境中却表现出严重的灭绝，并且由于无法解释的原因，在淡水环境中绝灭的情况要少得多。海洋环境中的灭绝是由于大气中的尘埃和烟尘使地球表面的日照持续数月至数年的“影响冬天”的影响所致。光合作用的停止导致浮游植物类群在全球范围内绝种。由于与陆地环境不同，水生生态系统强烈依赖自养生物的日常光合作用输出，因此浮游植物的丧失可能导致水生生态系统的灾难性死亡和灭绝。在水生生态系统中其他导致死亡的潜在原因包括由于缺乏光合氧气而导致的环境温度降低和缺氧。内陆水域虽然可能具有很高的死亡率，但其灭绝比例却比海洋环境低，这可能是由于淡水类群中具有更多的休眠潜能，通过快速流动来抵消氧气需求而进行的再生产效率更高，地下水在适中的温度，以及对淡水类群的预先适应在很大程度的环境变化中。此外，碎屑饲养者在海洋或淡水环境中似乎都具有较低的灭绝率，但由于与土壤直接水文接触，碎屑有机物的更新速率较高，因此再次有利于淡水类群。

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