EAGER: Development of the cyanotoxins, cylindrospermopsin and microcystin, as paleolimnological tools

湖泊水质随着温度升高和营养物富集而变化，导致藻类大量繁殖。藻华的增加通常包括蓝藻，蓝藻能够产生称为蓝藻毒素的毒素。这些蓝藻毒素对人类健康和其他生活在湖泊中或饮用湖泊水的动物有害。关于藻华和蓝藻毒素的历史数据很少，这使得人们很难理解它们已经发生了多久以及是什么导致它们发生。本计画将借由研究湖泊沉积物中保存的蓝藻毒素的历史记录，增进我们对藻华与蓝藻毒素发生的了解。在将湖泊沉积物中的蓝藻毒素与湖泊水体中的历史产量联系起来方面存在重大挑战。EAGER项目将开发创新方法来提取和测量湖泊沉积物中的蓝藻毒素，并进行实验以量化毒素在各种环境条件下的降解情况。然后，研究人员将对佛罗里达哈里斯湖的这些毒素的历史产量做出关键性的决定。从这个项目的结果将是广泛有用的标准方法，为所有湖泊和水库的蓝藻毒素的研究，并将提供湖泊和城市的水管理人员一个新的工具，以获取蓝藻毒素数据在较长的时间尺度。该项目还将为研究生、本科生和高中生，包括代表性不足群体的成员提供研究培训。虽然这些古湖沼学调查提供了急需的历史蓝藻毒素生产的记录，它是未知的，如果在古蓝藻毒素地层的变化导致毒素生产，降解或沉积的改变。因此，将蓝藻毒素作为替代物的沉积物研究有可能错误地推断出历史上的毒素生产。这项研究将建立蓝藻毒素水沉积物的连接，开发创新的分析协议，并确定蓝藻毒素沉积物的研究cylindrospermopsin和微囊藻毒素的尖端降解指数。此外，这些实验的结果将用于验证蓝藻沉积与整个全新世的历史富营养化和湖沼变化的已知时期。这项研究的目的是：1）通过将表层沉积物中的蓝藻毒素浓度与已知的水柱蓝藻毒素值相匹配，并改进提取方法，建立沉积物-水柱蓝藻毒素的联系，2）确定各种环境变量下各种沉积物类型中CYN和MC的降解系数（温度、氧、有机质含量）的变化，和3）从沉积物岩心中识别蓝藻毒素和蓝藻色素的地层变化。该奖项反映了NSF的法定使命，并已被视为通过使用基金会的知识价值和更广泛的影响审查标准进行评估，

The quality of water in lakes changes with increasing temperature and nutrient enrichment that leads to algal blooms. Increases in algal blooms typically include cyanobacteria, which are capable of producing toxins called cyanotoxins. These cyanotoxins are harmful to human health and to other animals that live in or drink water from the lakes. There is little, historical data on algal blooms and cyanotoxins, which makes it difficult to understand how long they have been occurring and what makes them happen. This project will advance our understanding of algal blooms and cyanotoxin occurrence by focusing on the historical record of cyanotoxins that are preserved in the sediments of lakes. There are significant challenges in relating the cyanotoxin in lake sediments to their historic production in the water column of lakes. This EAGER project will develop innovative methods to extract and measure cyanotoxins in lake sediment, and conduct experiments to quantify how the toxins degrade under various environmental conditions. Researchers will then make critical determinations of historic production of these toxins for Lake Harris in Florida. Results from this project will be broadly useful in developing standard methods for the study of cyanotoxins in all lakes and reservoirs, and will provide lake and municipal water managers a new tool to acquire cyanotoxin data on a longer time scale. This project will also provide research training for graduate, undergraduate and high school students, including members of underrepresented groups. While these paleolimnological investigations are providing much needed records of historic cyanotoxin production, it is unknown if changes in paleo-cyanotoxin stratigraphies result from alterations in toxin production, degradation or deposition. As a result, sediment studies incorporating cyanotoxins as a proxy are at risk to incorrectly infer historic toxin production. This research will establish cyanotoxin water-sediment connections, develop innovative analytical protocols, and cutting-edge degradation indices for determining cyanotoxin sediment studies on cylindrospermopsin and microcystin. In addition, results from these experiments will used to verify cyanotoxin deposition with known periods of historic eutrophication and limnological change throughout the Holocene. The objectives of the study are: 1) develop sediment-water column connections for cyanotoxins by matching surface sediment cyanotoxin concentrations with known water column cyanotoxin values and improving extraction methods, 2) determine degradation coefficients for CYN and MC in a variety of sediment types under a range of environmental variables (temperature, oxygen, organic matter content) experienced in lake sediment environments, and 3) identify stratigraphic changes of cyanotoxins and cyanobacteria pigments from sediment cores.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.