Wildfires are an environmental concern due to the loss of forest area and biodiversity, but also because their role as drivers of freshwater systems contamination by metals. In this context, the fish Gambusia holbrooki was used as a model, deployed for in situ exposure in watercourses standing within a recently burnt area and further assessment of toxic effects. The fish were exposed during 4 days at four different sites: one upstream and another downstream the burnt area and two within the burnt area. Biochemical biomarkers for oxidative stress and damage were assessed. The extent of lipoperoxidative damage was monitored by quantifying malondialdehyde and DNA damage evaluated through erythrocyte nuclear abnormalities observation. Chemical analysis revealed higher metal levels within the burnt area, and exposed fish consistently showed pro-oxidative responses therein, particularly an increase of gill glutathione peroxidase and glutathione reductase activity, the records doubling compared to samples from sites in the unburnt area; also the activity of glutathione-S-transferases comparatively increased (by 2-fold in the liver) in samples from the burnt area, and malondialdehyde was produced twice as much therein and in samples downstream the burnt area reflecting oxidative damage. Consistently, the frequency of erythrocyte nuclear abnormalities was higher at sites within and downstream the burnt area. This study supports the use of sensitive oxidative stress and genotoxicity biomarkers for an early detection of potentially noxious ecological effects of wildfires runoff.

由于森林面积和生物多样性的丧失，野火也是一个环境问题，而且还因为野火是淡水系统受到金属污染的驱动因素。在这种情况下，鱼Gambusia holbrooki被用作模型，用于在最近燃烧区域内的水道中进行原位暴露并进一步评估毒性影响。这些鱼在 4 天内暴露在四个不同地点：一个位于烧焦区域的上游，另一个位于烧焦区域的下游，还有两个位于烧焦区域内。评估氧化应激和损伤的生化生物标志物。通过量化丙二醛来监测脂质过氧化损伤的程度，并通过红细胞核异常观察来评估DNA损伤。化学分析显示，烧焦区域内金属含量较高，暴露的鱼始终表现出促氧化反应，特别是鳃谷胱甘肽过氧化物酶和谷胱甘肽还原酶活性增加，与未烧毁区域的样本相比，记录增加了一倍；烧伤区域的样品中谷胱甘肽-S-转移酶的活性也相对增加（肝脏中增加了两倍），其中和烧伤区域下游的样品中产生的丙二醛是氧化损伤的两倍。一致地，烧伤区域内和下游部位红细胞核异常的频率较高。这项研究支持使用敏感的氧化应激和遗传毒性生物标志物来早期检测野火径流的潜在有害生态影响。