Changes in the terrestrial environment and their effect on marine carbonates

陆地环境的变化及其对海洋碳酸盐的影响

• 批准号: RGPIN-2021-02785
• 负责人: Corlett, Hilary
• 金额: $ 2.19万
• 依托单位: Memorial University of Newfoundland
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=743855
• 关键词: Changes; terrestrial; environment; their; effect

Increased terrestrial runoff associated with coastal development results in fine particles suspended in shallow marine waters, which clogs pores in coral skeletons and reduces the amount of sunlight reaching the reefs. Excess nutrients associated with runoff are also harmful to reefs because they have negative impacts on the relationship between coral hosts and their photosynthetic symbionts. The immediate impacts of siltation and enhanced nutrients on reefs are fairly well understood; however, there are few studies examining the long-term effects of enhanced weathering or how carbonate producing biota in non-reef environments may be affected by these stressors. The overall objective of this research program is to evaluate the effects of terrestrial runoff and associated nutrients in various marine environments and through a range of timescales. This research proposal focuses on two main objectives that examine: 1) the effect the Earth's first forests and soils had on Devonian (Frasnian - 380 Ma) reefs; and 2) the effects of runoff in modern non-reef environments. The Frasnian expansion of forests and development of root networks, known as the punctata Event (pE), resulted in the world's first soils. It is assumed that this event had an effect on carbonate producing biota in the world's oceans since modern reefs suffer from increased soil runoff; however, the effects of this event on Frasnian reefs has not been explored. The proposed research examines the impact of the pE on ancient reefs that are well-preserved in the Western Canadian Sedimentary Basin. The research will also entail correlation of biogenically-sourced silicas in marine shales, which may represent ancient phytoplankton blooms, coeval with the pE, and responsible for enhanced bottom water anoxia observed worldwide at this time. The second aspect of this research proposal investigates the impact of terrestrial runoff, associated nutrients, and heavy metals on carbonate-producing biota in two modern settings: a lagoon in Grand Cayman and across an inner carbonate ramp in Abu Dhabi. The recent sedimentary record (<1000 years) will be interrogated for foraminifera and sediment geochemistry. Foraminifera are sensitive to changes in nutrient levels where, comparable to corals, larger symbiont-bearing foraminifera are replaced by generalist taxa. These generalist taxa also positively correlate with metals in sediments. The ultimate goal of this research is to determine how increased runoff along developed coastlines has impacted carbonate-producing marine biota in non-reef environments and develop criteria that may help us to recognize the effects of nutrification in ancient environments.

与沿海发育相关的陆生径流增加导致悬浮在浅海水域中的细颗粒，这些颗粒堵塞了珊瑚骨架中的孔，并减少了到达珊瑚礁的阳光量。与径流相关的过量营养素也对珊瑚礁有害，因为它们对珊瑚宿主与光合作用共生体之间的关系产生负面影响。淤积和增强的养分对珊瑚礁的直接影响是相当充分的。但是，很少有研究研究增强风化的长期影响或在非REEF环境中如何产生碳酸盐的生物群可能会受到这些压力源的影响。该研究计划的总体目的是评估各种海洋环境中陆地径流和相关营养素的影响，并通过一系列时间表。这项研究提案的重点是研究：1）地球上第一批森林和土壤对泥盆纪（弗拉斯尼亚-380 MA）礁石的影响； 2）在现代非Reef环境中径流的影响。 弗拉斯尼亚森林的扩展和根网的发展（称为Punctata事件（PE））导致了世界上第一批土壤。假设这一事件对世界海洋中的碳酸盐产生生物群产生了影响，因为现代礁石遭受了土壤径流的增加。但是，尚未探索此事件对弗拉斯尼亚礁的影响。拟议的研究研究了PE对加拿大西部沉积盆地保存完好的古代珊瑚礁的影响。这项研究还将需要在海洋页岩中生物生物产生的硅的相关性，这可能代表古代浮游植物盛开，与PE一起使用，并负责此时在全球范围内观察到的底部水缺氧。该研究建议的第二个方面研究了陆地径流，相关营养素和重金属对碳酸盐产生的生物群的影响：在两个现代环境中：大开曼氏念珠和阿布扎比的内部碳酸盐坡道。最近的沉积记录（<1000年）将因有孔虫和沉积物地球化学而受到质疑。有孔虫对养分水平的变化敏感，在这种变化中，与珊瑚相当，较大的含有共生的有孔虫被通才分类群代替。这些通才分类群也与沉积物中的金属呈正相关。这项研究的最终目的是确定发达海岸线的径流如何影响非REEF环境中产生碳酸盐的海洋生物群，并制定标准，这可能有助于我们认识到古代环境中营养的影响。