The exponential increase of the human population demands the overuse of fertilizers and pesticides in agriculture practices to suppress food production needs. The excessive use of these chemicals (fertilizers and pesticides) can comport deleterious effects to the ecosystems, including aquatic systems and communities. Oxyfluorfen is a fluorine-based herbicide, and its application has increased, since it is seen as an alternative to control glyphosate-resistant weeds. Copper sulfate is an inorganic pesticide based on copper which is being used in several chemical formulations, and it is the second main constituent of fungicides. Besides the known effects of such products in organisms, climatic changes pose an additional issue, being a main concern among scientists and politicians worldwide, since these alterations may worsen ecosystems’ and organisms’ sensitivity to stress conditions, such as the exposure to pollutants. Thalassiosira weissflogii (Grunow) G. A. Fryxell & Hasle, 1977 plays an important role in aquatic food webs as a primary producer and an essential food source to zooplankton. Thus, alterations on the diatom’s abundance and nutritional value may lead to consequences along the trophic chain. However, few studies have evaluated the biochemical impacts of oxyfluorfen and copper sulfate exposure on diatoms. This study intends to (1) evaluate the effects on the growth rate of both contaminants on T. weissfloggi at three temperatures, considering the actual scenario of climatic changes, and (2) assess biochemical changes on the diatom when exposed to the chemicals at different temperatures. To achieve these aims, the marine diatom was exposed to the two chemicals individually at different temperatures. The results showed an increase in the growth rate with increasing temperatures. Oxyfluorfen exhibited higher toxicity than copper sulfate. At the biochemical level, the microalgae were greatly affected when exposed to oxyfluorfen at 20 °C and 25 °C and when exposed to copper sulfate at 15 °C. Moreover, a general increase was observed for the polysaccharide content along the copper sulfate and oxyfluorfen concentrations. Therefore, the contaminants show the ability to interfere with the diatom growth and the nutritive value, with their effects dependent on the temperature.

中文翻译：

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三种不同温度情景下两种农药对海藻硅藻的生化作用

人口的指数增长要求在农业实践中过度使用化肥和杀虫剂来抑制粮食生产需求。过度使用这些化学品（肥料和杀虫剂）会对生态系统产生有害影响，包括水生系统和社区。氧氟草醚是一种氟基除草剂，它的应用有所增加，因为它被视为控制抗草甘膦杂草的替代品。硫酸铜是一种基于铜的无机农药，被用于多种化学制剂中，它是杀菌剂的第二主要成分。除了这些产品对生物体的已知影响外，气候变化带来了另一个问题，这是全世界科学家和政治家的主要关注点，Thalassiosira weissflogii (Grunow) GA Fryxell & Hasle, 1977 作为主要生产者和浮游动物的重要食物来源，在水生食物网中发挥着重要作用。因此，硅藻丰度和营养价值的改变可能会导致沿营养链的后果。然而，很少有研究评估氧氟草醚和硫酸铜暴露对硅藻的生化影响。本研究旨在 (1) 评估两种污染物对T.weissfloggi生长速率的影响在三个温度下，考虑到气候变化的实际情况，以及 (2) 评估硅藻在不同温度下暴露于化学物质时的生化变化。为了实现这些目标，海洋硅藻在不同温度下分别暴露于两种化学物质。结果表明，随着温度的升高，生长速度增加。氧氟菌灵表现出比硫酸铜更高的毒性。在生化水平上，微藻在暴露于 20°C 和 25°C 的氧氟草醚和暴露于 15°C 的硫酸铜时受到很大影响。此外，观察到多糖含量随着硫酸铜和氧氟草醚浓度的增加而普遍增加。因此，污染物显示出干扰硅藻生长和营养价值的能力，