Embrapa Cerrados (Empresa Brasileira de Pesquisa Agropecuária), Road BR-020, km 18, Planaltina, Federal District (DF), 73310-970, Brazil.
University of Brasília, Faculty UnB at Planaltina (FUP), Planaltina, Federal District (DF), 73345-010, Brazil.
Environ Sci Pollut Res Int. 2017 Aug;24(24):19671-19682. doi: 10.1007/s11356-017-9578-0. Epub 2017 Jul 6.
In a global scenario of climate change, several studies have predicted an increase in fires in different parts of the world. With the occurrence of rains following the fires in the Brazilian savanna (Cerrado biome), the compounds present in ashes may enter aquatic environments and cause adverse effects to these ecosystems. In this context, this study evaluated the potential toxicity of ashes from two areas of Cerrado and an area of pasture, through ecotoxicological bioassays and using three aquatic species from distinct trophic levels, which were exposed to different dilutions of ashes: the microcrustacean Ceriodaphnia dubia, the fish Danio rerio and the mollusc Biomphalaria glabrata. The ashes from the three sampled areas showed higher concentrations of some elements in relation to the soil samples (B, Ca, K, Mg, Mn, P, S, Si, Sr, Zn), but only a small quantity of these compounds was solubilised. Our data showed that all ash samples caused acute toxicity to C. dubia (48hs-LC = 13.4 g L; 48hs-LC = 6.33 g L; 48hs-LC = 9.73 g L respectively for transition area, pasture, typical cerrado areas), while in relation to D. rerio and B. glabrata, no acute toxicity was observed when they were exposed to ashes from native Cerrado vegetation and pasture areas. Ashes from a transition area showed toxicity for D. rerio (48hs-LC = 25.0 g L); possibly, this was due to the combination of multiple preponderant inorganic elements of ashes with other organic compounds not analysed, such as polycyclic aromatic hydrocarbons (PAHs). In summary, these results suggest that wildfires may pose risks to zooplankton communities and emphasize the need for more studies to better understand the complexity of the ecological effects of fire on aquatic ecosystems.
在气候变化的全球背景下，多项研究预测，世界不同地区的火灾将会增加。巴西热带稀树草原（塞拉多生物群系）火灾过后，灰烬中的化合物可能会进入水生环境，对这些生态系统造成不利影响。在这种情况下，本研究通过生态毒理学生物测定，使用来自不同营养级的三个水生物种（微型甲壳类动物 Ceriodaphnia dubia、鱼类 Danio rerio 和软体动物 Biomphalaria glabrata），评估了塞拉多两个地区和一个牧场地区灰烬的潜在毒性，并对这些物种暴露于不同浓度灰烬的情况进行了研究。与土壤样本相比，三个采样区域的灰烬中某些元素的浓度更高（B、Ca、K、Mg、Mn、P、S、Si、Sr、Zn），但只有少量这些化合物溶解。我们的数据表明，所有灰烬样本对 C. dubia 都具有急性毒性（48 小时-LC50 分别为 13.4、6.33 和 9.73 g/L，用于过渡区、牧场和典型塞拉多地区），而对于 D. rerio 和 B. glabrata，当它们暴露于原生塞拉多植被和牧场灰烬时，没有观察到急性毒性。过渡区的灰烬对 D. rerio 表现出毒性（48 小时-LC50 为 25.0 g/L）；这可能是由于灰烬中多种主要无机元素与其他未分析的有机化合物（如多环芳烃）的组合所致。综上所述，这些结果表明，野火可能对浮游动物群落构成威胁，并强调需要开展更多研究，以更好地了解火灾对水生生态系统的生态影响的复杂性。
