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Marine productivity largely controls the oceanic uptake of atmospheric carbon dioxide and contributed to the global climate changes that led to the termination of the last glacial cycle. Past changes in marine productivity were presumably associated with disturbances in the Atlantic meridional overturning circulation (AMOC). In the South Atlantic, however, the evolution of marine productivity throughout the last glacial–interglacial cycle is still poorly constrained mainly due to the scarcity of records with high temporal resolution. Here we present high‐resolution records of paleoproductivity and upper‐water‐column properties from the western subtropical South Atlantic covering the last 40,000 years. Our records are based on faunal and stable oxygen isotopic analyses of planktonic foraminifera from a marine sediment core collected from an upwelling region off southeastern South America (27°S). We used the relative abundance of eutrophic planktonic foraminifera (i.e., Globigerinita glutinata and Globigerina bulloides) as proxies of primary productivity. Our findings reveal, for the first time, enhanced primary productivity during Heinrich Stadials along the last glacial, when the AMOC showed reduced strength. Additionally, our results reveal decreased primary productivity over the Last Glacial Maximum, a period of markedly lower sea level; and the Younger Dryas, when the AMOC showed only moderate reductions. The most outstanding productivity decline, however, is depicted at the onset of the Holocene, when the AMOC recovers its strength. We hypothesize that the observed changes were triggered by the dynamics of the Brazil Current primarily driven by disturbances in the AMOC.
Marine productivity largely controls the oceanic uptake of atmospheric carbon dioxide and contributed to the global climate changes that led to the termination of the last glacial cycle. Past changes in marine productivity were presumably associated with disturbances in the Atlantic meridional overturning circulation (AMOC). In the South Atlantic, however, the evolution of marine productivity throughout the last glacial–interglacial cycle is still poorly constrained mainly due to the scarcity of records with high temporal resolution. Here we present high‐resolution records of paleoproductivity and upper‐water‐column properties from the western subtropical South Atlantic covering the last 40,000 years. Our records are based on faunal and stable oxygen isotopic analyses of planktonic foraminifera from a marine sediment core collected from an upwelling region off southeastern South America (27°S). We used the relative abundance of eutrophic planktonic foraminifera (i.e., Globigerinita glutinata and Globigerina bulloides) as proxies of primary productivity. Our findings reveal, for the first time, enhanced primary productivity during Heinrich Stadials along the last glacial, when the AMOC showed reduced strength. Additionally, our results reveal decreased primary productivity over the Last Glacial Maximum, a period of markedly lower sea level; and the Younger Dryas, when the AMOC showed only moderate reductions. The most outstanding productivity decline, however, is depicted at the onset of the Holocene, when the AMOC recovers its strength. We hypothesize that the observed changes were triggered by the dynamics of the Brazil Current primarily driven by disturbances in the AMOC.
This study focused on providing practical information to assess the current status of soil quality and land degradation in Quang Ninh province, Vietnam to provide more evidence on land degradation status and factors affecting land degradation in this area. The soil samples were collected and analyzed in 2020 and compared to the available data of soil analysis data collected at the Department of Natural Resources and Environment of Quang Ninh Province in 2010. The percentage of degraded land ranges from 51.70 to 90.36%. Forest land is the type with the highest percentage of degraded land with 90.36% of total forestry land area; Unused hilly land ranks second with degraded land at 87.15%; the percentage of degraded land in agriculture production land stays at 80.59%. The types of land degradation such as Condensation, Acidification, and Salinization only take place on a small area of land in the province. The cause of land degradation in Quang Ninh comes from both natural and anthropogenic causes. The main reasons can be mentioned as the terrain has a steep slope; the climate is hot and rainy; the climate change situation is complicated; and inappropriate agricultural practices. To solve the above situation, it is necessary to have solutions and integrated strategies for the rational exploitation and use of land resources. Especially environmentally friendly agricultural farming methods that are highly adaptive to climate change such as organic agriculture, circular agriculture, and sustainable agriculture.
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