English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The polar fractions extracted from sediments of the Imbe, Urubu, and Ururai rivers and from Lake de Cima were analyzed using gas chromatography and gas chromatography-mass spectrometry. In the samples, cholest-5-en-3b-ol, 24-methylcholest-5-en-3b-ol, 24-ethylcholest-5-en-3b-ol, 24-ethylcholesta-5,22-dien-3b-ol and their 5a-counterparts were dominant among the sterols. Sediments of theses water bodies have the C29 sterols as the most abundant, emphasizing a higher plant input. In the Ururai River, cholest-5-en-3b-ol predominated, reflecting a major algal contribution. Olean-12-en-3b-ol (b-amyrin) and friedelan-3-one were prevalent among the triterpenoids in the Imbe and the Urubu sediments, but were not detected at Lake de Cima. Samples of the Imbe and Urubu rivers contained appreciable concentrations of n-alkanols. They ranged from C14 to C32 with a maximum at C16 and with a second maximum in C28. Results of all four sediments point to a mixed contribution of higher plants and algae/zooplankton. Alkanols found in these water bodies indicate a greater contribution of higher plant material, while in sediments from the Ururai algae/zooplankton were the main sources of the organic matter.

A preliminary investigation of the polar lipids in recent tropical sediments from aquatic environments at Campos dos Goytacazes, Brazil