نتایج جستجو برای: siliceous composition
تعداد نتایج: 260770 فیلتر نتایج به سال:
Sponges show the highest diversity of associated bacteria among marine invertebrates. Immunological evidence traces the origin of the sponge bacterial symbioses to the Precambrian era. Hence, sponges appear to be ideally suited for studying the evolutionary origins of prokaryote-metazoan associations. Sponges produce either calcareous or siliceous skeletons, which only coexist in a relict group...
Although paraquat has been banned in European countries, this herbicide is still used all over the world, thanks to its low-cost, high-efficiency, and fast action. Because paraquat is highly toxic to humans and animals, there is interest in mitigating the consequences of its use, namely by implementing removal procedures capable of curbing its environmental and health risks. This research descr...
The 18-km-diameter El’gygytgyn crater is located on the Chukotka peninsula, northeastern Russia. It represents the only currently known impact structure formed in siliceous volcanics, including tuffs. The impact melt rocks and target rocks provide an excellent opportunity to study shock metamorphism of volcanic rocks. The shockinduced changes observed in porphyritic volcanic rocks from El’gygyt...
Siliceous Rhizaria (polycystine radiolarians and phaeodarians) are significant contributors to carbon silicon biogeochemical cycles. Considering their broad taxonomic diversity wide size range (from a few micrometres up several millimetres), comprehensive evaluation of the entire community cycles is challenging. Here, we assess contribution silicified global biogenic silica stocks in upper 500 ...
The Middle Eocene Climatic Optimum (MECO; ~ 40 million years ago [Ma]) is one of the most prominent transient global warming events in the Paleogene. Although the event is well documented in geochemical and isotopic proxy records at many locations, the marine biotic response to the MECO remains poorly constrained. We present new high-resolution, quantitative records of siliceous microplankton a...
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