Bacteriohopanepolyols along redox gradients in the Humboldt Current System off northern Chile.

摘要: Marine oxygen minimum zones (OMZs) are characterized by the presence of subsurface suboxic or anoxic waters where diverse microbial processes responsible for removal fixed nitrogen. OMZs have expanded over past decades and expected to continue expanding in response changing climate. The implications marine biogeochemistry, particularly nitrogen cycling, uncertain. Cell membrane lipids (biomarkers), such as bacterial bacteriohopanepolyols (BHPs) their degradation products (hopanoids), distinctive structural attributes that convey information about biological sources. Since discovery fossil hopanoids ancient sediments, study BHPs has been great biogeochemical interest due potential serve proxies bacteria geological record. A stereoisomer bacteriohopanetetrol (BHT), BHT II, previously identified OMZ unequivocally culture enrichments anammox bacteria, a key group contributing loss OMZs. We tested II proxy suboxia/anoxia suspended organic matter across Humboldt Current System off northern Chile, well surface deeply buried sediments (125–150 ky). ratio (BHT II/total BHT) increases content decreases through water column, consistent with previous results from Peru, Cariaco Basin Arabian Sea, line microbiological evidence indicating intense activity Chilean OMZ. Notably, is transported column preserved correlates changes δ15N sediment values during glacial–interglacial transitions. This suggests offers relative importance anammox, fluctuations cycling ocean redox