{"title":"Exceptionally high foraminiferal dissolution in the western Bay of Bengal","authors":"Sudhira R. Bhadra , Rajeev Saraswat","doi":"10.1016/j.ancene.2022.100351","DOIUrl":null,"url":null,"abstract":"<div><p><span>The planktic foraminifera are an important component of the global carbon cycle, as they sequester the carbon, thus burying it in the sediments for ages. The burial of planktic foraminiferal shells, however, depends on the carbonate chemistry of the deep ocean. A significant fraction of foraminiferal shells dissolves well above the carbonate compensation depth. The foraminiferal lysocline<span> is defined to delineate such zones of planktic foraminiferal dissolution well above the carbonate compensation depth. The dissolution of carbonate above the lysocline, termed supralysoclinal dissolution, has also been reported from highly productive basins. This study demarcates the extent of foraminiferal dissolution in the western Bay of Bengal. We document the distribution of planktic foraminifera and shell fragments in 100 core top samples collected from the coast perpendicular transects at depths ranging from 27 m to 2760 m. We examine the possible reasons for the foraminiferal dissolution by comparing the foraminiferal indices with the ambient bottom water parameters. The absolute abundance of planktic foraminifera is significantly low, both on the continental shelf and below ∼1000 m. The low abundance on the shelf is due to the terrigenous dilution. The fragmentation indices and the ratio between dissolution resistant and dissolution susceptible assemblage, however, confirm a significant increase in the dissolution at depths deeper than 1000 m. The foraminiferal shell dissolution at deeper depths is due to the high pressure, whereas the biogenic respiration-induced </span></span>calcite under-saturation is responsible for the significant dissolution at a very shallow depth in the western Bay of Bengal, as compared to other parts of the world ocean.</p></div>","PeriodicalId":56021,"journal":{"name":"Anthropocene","volume":null,"pages":null},"PeriodicalIF":3.3000,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Anthropocene","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2213305422000327","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENVIRONMENTAL SCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
The planktic foraminifera are an important component of the global carbon cycle, as they sequester the carbon, thus burying it in the sediments for ages. The burial of planktic foraminiferal shells, however, depends on the carbonate chemistry of the deep ocean. A significant fraction of foraminiferal shells dissolves well above the carbonate compensation depth. The foraminiferal lysocline is defined to delineate such zones of planktic foraminiferal dissolution well above the carbonate compensation depth. The dissolution of carbonate above the lysocline, termed supralysoclinal dissolution, has also been reported from highly productive basins. This study demarcates the extent of foraminiferal dissolution in the western Bay of Bengal. We document the distribution of planktic foraminifera and shell fragments in 100 core top samples collected from the coast perpendicular transects at depths ranging from 27 m to 2760 m. We examine the possible reasons for the foraminiferal dissolution by comparing the foraminiferal indices with the ambient bottom water parameters. The absolute abundance of planktic foraminifera is significantly low, both on the continental shelf and below ∼1000 m. The low abundance on the shelf is due to the terrigenous dilution. The fragmentation indices and the ratio between dissolution resistant and dissolution susceptible assemblage, however, confirm a significant increase in the dissolution at depths deeper than 1000 m. The foraminiferal shell dissolution at deeper depths is due to the high pressure, whereas the biogenic respiration-induced calcite under-saturation is responsible for the significant dissolution at a very shallow depth in the western Bay of Bengal, as compared to other parts of the world ocean.
AnthropoceneEarth and Planetary Sciences-Earth and Planetary Sciences (miscellaneous)
CiteScore
6.30
自引率
0.00%
发文量
27
审稿时长
102 days
期刊介绍:
Anthropocene is an interdisciplinary journal that publishes peer-reviewed works addressing the nature, scale, and extent of interactions that people have with Earth processes and systems. The scope of the journal includes the significance of human activities in altering Earth’s landscapes, oceans, the atmosphere, cryosphere, and ecosystems over a range of time and space scales - from global phenomena over geologic eras to single isolated events - including the linkages, couplings, and feedbacks among physical, chemical, and biological components of Earth systems. The journal also addresses how such alterations can have profound effects on, and implications for, human society. As the scale and pace of human interactions with Earth systems have intensified in recent decades, understanding human-induced alterations in the past and present is critical to our ability to anticipate, mitigate, and adapt to changes in the future. The journal aims to provide a venue to focus research findings, discussions, and debates toward advancing predictive understanding of human interactions with Earth systems - one of the grand challenges of our time.