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

湖泊的水质随着温度的升高和营养物的富集而变化，从而导致藻华。藻华的增加通常包括蓝藻细菌，它能够产生一种叫做蓝藻毒素的毒素。这些蓝藻毒素对人类健康和其他生活在湖中或饮用湖水的动物有害。关于藻华和蓝藻毒素的历史数据很少，这使得很难理解它们发生的时间和发生的原因。该项目将通过关注保存在湖泊沉积物中的蓝藻毒素的历史记录，推进我们对藻华和蓝藻毒素发生的理解。将湖泊沉积物中的蓝藻毒素与其在湖泊水柱中的历史生产联系起来存在重大挑战。该EAGER项目将开发创新的方法来提取和测量湖泊沉积物中的蓝藻毒素，并进行实验来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州哈里斯湖历史上这些毒素的产生进行关键的确定。该项目的研究结果将广泛用于制定所有湖泊和水库中蓝藻毒素研究的标准方法，并将为湖泊和市政供水管理人员提供一种新的工具，以获取更长时间尺度的蓝藻毒素数据。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。虽然这些古湖泊学调查提供了非常需要的历史蓝藻毒素产生的记录，但尚不清楚古蓝藻毒素地层的变化是否源于毒素产生、降解或沉积的改变。因此，以蓝藻毒素为代表的沉积物研究有可能错误地推断出历史上的毒素产生。本研究将建立蓝藻毒素与沉积物之间的联系，开发创新的分析方案，以及用于测定圆柱形精子蛋白酶和微囊藻毒素的蓝藻毒素沉积物的前沿降解指标。此外，这些实验的结果将用于验证蓝藻毒素沉积与整个全新世历史富营养化和湖泊变化的已知时期。这项研究的目的是：1)通过将表层沉积物蓝毒素浓度与已知水柱蓝毒素值进行匹配并改进提取方法，建立沉积物-水柱间蓝毒素的联系；2)在湖泊沉积物环境中经历的一系列环境变量（温度、氧气、有机质含量）下，确定各种沉积物类型中CYN和MC的降解系数；3)鉴定沉积物岩心中蓝藻毒素和蓝藻色素的地层变化。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

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.