Barros Thayanne L, Mayer-Pinto Mariana, Dafforn Katherine A, Simpson Stuart L, Farrell Mark, Bracewell Sally A, Johnston Emma L
Centre for Marine Science and Innovation, University of New South Wales, NSW, 2052, Australia.
Centre for Marine Science and Innovation, University of New South Wales, NSW, 2052, Australia.
Chemosphere. 2025 Sep;385:144604. doi: 10.1016/j.chemosphere.2025.144604. Epub 2025 Aug 2.
Climate change is increasing wildfire intensity, introducing new risks to estuarine systems. However, the impacts of wildfires on estuaries and their recovery remain poorly understood. To address this, we conducted a large-scale longitudinal survey investigating sediment quality across river-to-estuary systems affected by fire. We measured concentrations of carbon, nutrients, chlorophyll-a, and silt content in sediment at 90 sites across six waterways with varying extents of burnt catchment area. Pyrogenic carbon (PyC), measured using mid-infrared spectroscopy, proved a reliable indicator of fire impacts, whereas nutrients levels varied more with seasonal changes. PyC concentrations declined significantly over 12 months post-fire, halving in most fire-affected estuaries. However, in one catchment with 92 % burnt area, there was no reduction in the concentration of PyC within 12 months, suggesting prolonged impact. Fire location and burnt area extent influenced temporal PyC trends. This study is the first to assess sediment quality over time in the upper, middle and lower estuarine sections following wildfires. Our findings are important for managing coastal areas amid increasing wildfire frequency and severity. Using PyC as a stable indicator of fire impact can improve monitoring and guide recovery efforts, helping safeguard estuarine health and function.
气候变化正在加剧野火强度，给河口系统带来新的风险。然而，野火对河口的影响及其恢复情况仍知之甚少。为了解决这个问题，我们进行了一项大规模的纵向调查，研究受火灾影响的从河流到河口系统的沉积物质量。我们测量了六条水道中90个地点沉积物中的碳、营养物质、叶绿素a和淤泥含量，这些水道的集水区烧毁面积各不相同。使用中红外光谱法测量的热解碳（PyC）被证明是火灾影响的可靠指标，而营养物质水平随季节变化的差异更大。火灾发生后的12个月内，热解碳浓度显著下降，在大多数受火灾影响的河口减半。然而，在一个烧毁面积达92%的集水区，12个月内热解碳浓度没有下降，表明影响持续时间较长。火灾位置和烧毁面积范围影响了热解碳的时间趋势。本研究首次评估了野火后河口上段、中段和下段沉积物质量随时间的变化。我们的研究结果对于在野火频率和严重程度不断增加的情况下管理沿海地区具有重要意义。将热解碳用作火灾影响的稳定指标可以改善监测并指导恢复工作，有助于保护河口的健康和功能。
