School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, United Kingdom.
Department of Materials and London Centre for Nanotechnology, Imperial College London, London SW7 2AZ, United Kingdom.
Sci Total Environ. 2022 Jul 20;831:154616. doi: 10.1016/j.scitotenv.2022.154616. Epub 2022 Mar 18.
Impacts of widespread release of engineered titanium dioxide nanoparticles (nTiO) on freshwater phytoplankton and phytobenthic assemblages in the field, represents a significant knowledge gap. Using outdoor experiments, we quantified impacts of nTiO on phytoplankton and periphyton from UK rivers, applied at levels representative of environmentally realistic concentrations (0.05 mg/L) and hot spots of accumulation (5.0 mg/L). Addition of nTiO to river water led to rapid temporal size changes in homoagglomerates and many heteroaggregates of nTiO with cells in the phytoplankton, including green algae, pennate and centric diatoms, increasing settlement of some cells. Changes in phytoplankton composition were evident after 72-h resulting from a significant decline in the relative abundance of very small phytoplankton cells (1-3 μm), often accompanied by increases in centric diatoms at both concentrations. Significant changes detected in the composition of the phytobenthos after 12 days, following nTiO treatments, were not evident when using benthic diatoms alone after 56 days. A lack of inhibition in the maximum quantum yield (Fv/Fm) in phytobenthos after 72-h exposures contrasted with a significant inhibition in Fv/Fm in 75% of phytoplankton samples, the highest recorded in Rutile nTiO exposures at both concentrations of nTiO. After 12 days, strong positive stimulatory responses were recorded in the maximum relative electron transport rate (rETR) and the maximum non-photochemical coefficient (NPQ), in phytoplankton and phytobenthos samples exposed to the higher Anatase nTiO concentration, were not measured in Rutile exposed biota. Collectively, these results indicate that the Rutile phase of nTiO has more negative impacts on freshwater algae than the Anatase form, at specific time scales, and phytoplankton may be more impacted by nTiO than phytobenthos. We caution that repeated release of nTiO, could lead to significant changes in riverine algal biomass and species composition, dependent on the phase and concentration of nTiO.
广泛释放工程化二氧化钛纳米颗粒（nTiO）对野外淡水浮游植物和底栖藻类群落的影响是一个重大的知识空白。本研究采用野外实验，量化了 nTiO 对英国河流浮游植物和周丛藻类的影响，施加的浓度水平代表了环境现实浓度（0.05mg/L）和积累热点（5.0mg/L）。将 nTiO 添加到河水中会导致 nTiO 与浮游植物细胞的同质聚集体和许多异质聚集体迅速发生时间尺度上的变化，增加了一些细胞的沉降。72 小时后，浮游植物组成发生明显变化，主要表现为非常小的浮游植物细胞（1-3μm）的相对丰度显著下降，同时在两种浓度下，中心硅藻的数量都有所增加。在 nTiO 处理后 12 天，底栖藻类的组成发生了显著变化，但在 56 天后，仅使用底栖硅藻则没有明显变化。在 72 小时暴露后，底栖藻类的最大量子产量（Fv/Fm）没有受到抑制，而在 75%的浮游植物样本中，Fv/Fm 受到了显著抑制，这是在两种浓度的 nTiO 中锐钛矿 nTiO 暴露时记录到的最高值。在 12 天后，在暴露于较高浓度的锐钛矿 nTiO 的浮游植物和底栖藻类样本中，最大相对电子传递速率（rETR）和最大非光化学淬灭系数（NPQ）均记录到强烈的正刺激响应，但在暴露于金红石型 nTiO 的生物群中未测量到这些响应。总的来说，这些结果表明，在特定的时间尺度内，nTiO 的锐钛矿相比金红石相对淡水藻类的负面影响更大，而且浮游植物可能比底栖藻类更容易受到 nTiO 的影响。我们警告说，nTiO 的反复释放可能导致河流藻类生物量和物种组成发生重大变化，这取决于 nTiO 的相和浓度。
