Assessing the photocatalytic effects of metal-oxide nanoparticles on marine organisms under environmentally-relevant light regimes

二氧化钛（TiO2）纳米粒子（NPs）是工业和消费品中应用最广泛的人造纳米材料之一，预计未来10年的环境负荷将高达200万至600万吨。毒理学上，工程TiO2 NPs已经得到了很好的研究，大部分工作是在细胞系、细菌和啮齿动物上进行的。报道的影响包括炎症，氧化应激和DNA损伤，但高度依赖于暴露方法，以及NPs的浓度和物理化学特性。其他研究已经检测了TiO2 NPs作为氧化污染物、饮用水消毒或治疗肿瘤的一种方式的光催化特性。这些研究报告了各种光毒性效应，但通常使用的辐照度比在水生环境中发现的要高得多。一些研究已经检查了二氧化钛在自然光下对淡水生物的光毒性，但在近岸海洋群落方面的工作很大程度上缺乏。我们认为TiO2 NPs对浅水海洋生物的光毒性是一个被忽视的研究领域，这对于全面评估纳米技术的环境安全性至关重要。基于我们在海洋生物学、金属化学和海洋光学方面的丰富经验，我们开发了几条研究路线，研究TiO2在环境相关条件下的光催化效应。我们的项目符合纳米技术环境健康和安全计划的预算限制，并且代表了一个令人兴奋的研究领域，学生和pi将在其中工作。具体来说，我们将研究：1)将纳米级TiO2掺入到自然发生的异质聚集物（即海洋雪）中；2)对生活在海洋雪复合体内的重要微生物群的光毒性；3)海洋雪对两种近岸底栖滤食性动物的营养转移效率；4)随后对这两种动物（一种半透明动物，一种不透明动物）的生理和细胞过程的光催化作用。智力优势：本研究首次综合考虑了常见的海洋学过程（如海洋雪的形成）和环境相关的光机制，以评估1)TiO2 NPs对微生物群落和在海洋生态系统中起关键作用的底栖滤食性动物的光催化影响，以及2)底栖生物的营养转移和生物可利用性。确定NPs对关键底栖生物群体的潜在有害影响不仅具有比较意义，而且对于确定这些物质如何产生群落水平的影响也很重要。例如，对滤食性动物的毒性影响会损害它们对底栖-远洋耦合的能力，进而极大地影响周围环境。我们的研究产生的知识将对关注海产品安全的监测机构、正在制定风险评估协议的监管机构、研究新出现污染物分布的科学家以及设计“绿色”纳米技术的工程师很有意义。由于我们处于此类研究的前沿，我们的结果很可能会立即为海洋系统提供重要数据，并有助于关于NPs在环境中的潜在安全性的辩论。更广泛的影响：作为我们工作的自然延伸，我们将培养本科生和研究生在生物学，化学和光学学科的概念和技术。我们的研究计划将作为一种工具，让教育工作者和学生参与讨论近岸生态系统过程，以及纳米技术的好处和潜在危害。在幼儿时期为科学发现提供积极和有趣的学习机会，是抓住学习热情的关键。因此，我们将侧重于编写和实施创新教材，宣传海洋环境对人类健康的重要性。教材将与非营利性海洋科学教育组织新英格兰科学与航海（NESS）合作设计。与NESS合作，我们将：1)制定课程计划，以引人入胜和可理解的方式展示推动沿海生态系统的基本原则，并探索新出现的污染物与海洋和人类健康之间的联系；2)培训NESS高级员工利用这些课程培养生态素养，吸引学生进入科学和工程领域。

CBET - 1336358 Titanium dioxide (TiO2) nanoparticles (NPs) are one of the most widely used manufactured nanomaterials in industrial and consumer products, with predicted environmental loads as high as 2,000,000 to 6,000,000 tons in the next 10 years. Toxicologically, engineered TiO2 NPs have been well studied with most work being performed on cell lines, bacteria, and rodents. The reported effects include inflammation, oxidative stress, and DNA damage, but are highly dependent on exposure method, and the concentration and physicochemical characteristics of the NPs. Other research has examined the photocatalytic properties of TiO2 NPs as a way of oxidizing contaminants, disinfecting drinking water, or treating tumors. These studies have reported various phototoxic effects, but typically use irradiances much higher than those found in aquatic settings. A few studies have examined the phototoxicity of TiO2 on freshwater organisms under natural light regimes, but work on near-shore marine communities is largely lacking. We argue that the phototoxicity of TiO2 NPs on shallow-water marine organisms is an overlooked area of research which is critical for a full assessment of the environmental safety of nanotechnology. Based on our extensive experience with a marine biology, metal chemistry and ocean optics, we have developed several lines of research that examine the photocatalytic effects of TiO2 under environmentally-relevant conditions. Our projects fit within the budgetary constraints of the Environmental Health and Safety of Nanotechnology program, and represent an exciting area of research in which students and PIs will work. Specifically, we will investigate: 1) incorporation of nanoscale TiO2 into naturally occurring hetero-aggregations (i.e., marine snow); 2) phototoxicity on important groups of microorganisms that live within the marine-snow complex; 3) trophic transfer efficiency via marine snow to two species of near-shore, benthic filter feeders; 4) subsequent photocatalytic effects on the physiology and cellular processes of these two animals (one translucent, one opaque).Intellectual Merit :The proposed work represents the first comprehensive study to consider common oceanographic processes (e.g., formation of marine snow) and environmentally-relevant light regimes in assessing 1) photocatalytic impacts of TiO2 NPs on microbial communities and benthic filter feeders that play key roles in marine ecosystems, and 2) trophic transfer and bioavailability to benthic organisms. Determining the potential deleterious effects of NPs on key groups of benthic organisms is not only important for comparative purposes, but also to determine how such materials might produce community level impacts. For example, toxic effects on filter feeders would compromise their capacity for benthic-pelagic coupling and, in turn, greatly impact the surrounding environment. Knowledge generated by our research will be of interest to monitoring agencies concerned with seafood safety, regulators who are developing risk-assessment protocols, scientists who study the distribution of emerging pollutants, and engineers who are designing "green" nanotechnology. As we are at the forefront of such research it is likely that our results will immediately yield important data for marine systems, and contribute to the debate regarding the potential safety of NPs in the environment.Broader Impacts :As a natural extension of our work we will train undergraduate and graduate students in concepts and techniques that cross the disciplines of biology, chemistry, and optics. Our research program will be used as a vehicle to engage educators and students in discussions about near-shore ecosystem processes, and the benefits and potential hazards of nanotechnology. Offering positive and entertaining learning opportunities for scientific discovery at an early age is crucial to capturing the enthusiasm for learning. Consequently, we will focus on developing and implementing innovative teaching materials that advocate the importance of marine environments to human health. The teaching materials will be designed in collaboration with New England Science & Sailing (NESS), a non-profit marine-science educational organization. In collaboration with NESS we will: 1) Develop lesson plans that demonstrate, in an engaging and understandable way, basic principles that drive coastal ecosystems, and explore the links between emerging pollutants and oceans and human health; 2) Train NESS senior staff to use these lessons to foster ecological literacy and draw students into science and engineering.