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A new look at glaciers regulating global silicon cycles

A new review of silicon cycles in a glacial environment, led by scientists from the University of Bristol, highlights the potential importance of glaciers in exporting silicon to lower-order ecosystems.

According to the researchers, this could affect primary productivity at sea and affect the carbon cycle on the ice age timeframe.

This is because silica is needed by primary producers, such as diatoms (the form of algae, which make up 35 percent of all marine primary productivity), and these original producers remove significant amounts of carbon dioxide from the atmosphere, moving it to the deep ocean.

Lead author Jade Hatton of the University of Bristol & # 39; s School of Earth Sciences said: "It is important for us to understand the role of glaciers in silicon cycles and to analyze previously published papers on glaciality and nutrient flows to gather this review, focusing to the chemical fingerprint of silicon exported from these environments. "

The team, whose findings were published this week in the journal Proceedings of Royal Society A, considered some of the "big questions" surrounding glaciers and silicon exports, including differences in the chemical fingerprint of silicon between glacial and non-glacial rivers, and if weather processes occur under glaciers cause these differences.

By combining new foot water measurements from over 20 glaciers in Iceland, Alaska, Greenland and Norway with existing data, the document shows that the chemical fingerprint of silicon exported from glaciers is clear compared to silicon in rivers other than glaciers.

This chemical signature (the isotope composition of silicon) helps to understand the nature of weathering processes occurring under glaciers.

Jade Hatton added: "Data from such a range of glaciers are a significant undertaking in the field and are a huge improvement in our knowledge of the isotope signature of silicon from glaciers.

"We suggest that the clear isotope composition of silicon in glacial waters is due to high rates of physical erosion under glaciers.

"This has an impact on how we understand subglacial weathering and the export of nutrients from a glacial environment."

These new data were presented together with work previously carried out in Iceland and Greenland to provide stronger evidence of the relationship between icy melted water and a clear silicon isotope reference.

Researchers hope that this broader data set will help in future develop more complex computer models based on our previous modeling work, which showed the importance of glacial silica in the time scales between glaciers.

The article also discusses the complexity of glacial environments and highlights some important questions that are still uncertain, including the importance of silica dust when considering overall glacial export flows.

Jade Hatton said: "Little has been done to understand the formation of this" amorphous "silica under glaciers. We suggest that high physical erosion in these systems is extremely important, but encourage future work to limit it even more.

"Another highly discussed area is currently the role of fjords in the recycling of nutrients, which causes uncertainty in nutrient flows from glaciers reaching the open ocean. Funding from ERC (ICY-LAB) and the Royal Society allows us to continue research in this field on projects including the biogeochemical cycle in the Greenland fjords.

"We are pleased to be able to shed light on these uncertainties by using a number of field study analyzes in these fjord environments."

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