Instituto do Mar, Universidade Federal de São Paulo (IMAR-UNIFESP), Rua Maria Máximo 168, 11030-100 Santos, SP, Brazil.
Escola de Química e Alimentos, Laboratório de Análise de Compostos Orgânicos e Metais (LACOM), Universidade Federal do Rio Grande, Av Itália, km 8, Rio Grande, RS 96201-900, Brazil.
Sci Total Environ. 2022 Apr 1;815:152944. doi: 10.1016/j.scitotenv.2022.152944. Epub 2022 Jan 7.
Natural pH values in coastal waters vary largely among locations, ecosystems, and time periods; still, there is an ongoing acidification trend. In this scenario, more acidic pH values can alter bioavailability of organic contaminants, to organisms. Despite this, interactive effects between pH and chemical substances are not usually considered in Ecological Risk Assessment protocols. This study investigated the effects of pH on the toxicity of a hydrophobic organic compound on a benthic community using a microcosm experiment setup to assess the response of nematode assemblages exposed to environmentally relevant concentrations of Irgarol at two natural pH conditions. Estuarine nematode assemblages were exposed to two concentrations of Irgarol at pH 7.0 and 8.0 for periods of 7 and 35 days. Lower diversity of nematode genera was observed at the highest tested Irgarol concentration (1281 ± 65 ng.g). The results showed that the effects of Irgarol contamination were independent of pH variation, indicating no influence of acidification within this range on the toxicity of Irgarol to benthic meiofauna. However, the results showed that estuarine nematode assemblages are impacted by long-term exposure to low (but naturally occurring) pHs. This indicates that estuarine organisms may be under naturally high physiological pressure and that permanent changes in the ecosystem's environmental factors, such as future coastal ocean acidification, may drive organisms closer to the edges of their tolerance windows.
沿海水域的自然 pH 值在地理位置、生态系统和时间段之间存在很大差异；尽管如此，仍存在持续酸化的趋势。在这种情况下，更低的 pH 值会改变有机污染物对生物的生物利用度。尽管如此，在生态风险评估方案中通常不考虑 pH 值和化学物质之间的交互作用。本研究使用微宇宙实验装置，调查了 pH 值对疏水性有机化合物对底栖生物群落毒性的影响，以评估在两种自然 pH 值条件下，暴露于环境相关浓度的 Irgarol 时线虫组合体的反应。在 pH 值为 7.0 和 8.0 时，河口线虫组合体分别暴露于两种浓度的 Irgarol 中 7 天和 35 天。在最高测试的 Irgarol 浓度（1281±65ng.g）下，观察到线虫属的多样性较低。结果表明，Irgarol 污染的影响与 pH 值变化无关，表明在该范围内酸化对 Irgarol 对底栖小型生物区系的毒性没有影响。然而，结果表明，河口线虫组合体受到长期暴露于低（但自然发生）pH 值的影响。这表明河口生物可能受到自然高生理压力的影响，生态系统环境因素的永久性变化，如未来的沿海海洋酸化，可能会使生物更接近其耐受窗口的边缘。
