Dissolved black carbon as a potential driver of surface water heating dynamics in wildfire-impacted regions: A case study from Pyramid Lake, NV, USA
Dissolved black carbon as a potential driver of surface water heating dynamics in wildfire-impacted regions: A case study from Pyramid Lake, NV, USA
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DOI：
10.1016/j.scitotenv.2023.164141
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发表时间：
2023-05-22
影响因子：
9.8
通讯作者：
Khlystov，Andrey
中科院分区：
文献类型：
--
作者：
Kruger，Brittany R.;Hausner，Mark B.;Khlystov，Andrey
炭黑(BC)是有机物不完全燃烧产生的致热残留物，从野火中以很高的速度释放出来。随后通过大气沉积或陆上流动进入水环境，形成溶解部分，称为溶解黑碳(DBC)。随着野火的频率和强度随着气候的变化而增加，了解DBC负荷的同时增加可能对水生生态系统产生的影响变得至关重要。在大气中，BC通过吸收太阳辐射来刺激变暖，含有DBC的地表水可能会发生类似的过程。在这项工作中，我们调查了环境相关水平的DBC的添加是否会在实验环境中影响地表水加热动力学。在火灾高峰期，在金字塔湖(内华达州，美国)的多个地点和深度对DBC进行了量化，同时燃烧了两场近距离的大型野火。在所有采样地点的金字塔湖水中都检测到了DBC，其浓度(3.6ppb-18ppb)明显高于其他大型内陆湖泊的报告浓度。DBC与发色溶解有机质呈正相关(R2= .84)，而与总溶解有机碳和总有机碳无关，表明DBC是湖泊光学活性有机物的重要组成部分。随后进行了基于实验室的实验，方法是在纯水中添加与环境相关的DBC标准，将系统暴露在太阳光谱辐射下，并根据观测到的温度创建热传递的数值模型。在与环境有关的数量级添加dbc导致暴露在太阳光谱下的短波反照率降低，导致水吸收的入射辐射增加5-8 %，并改变了水加热的动态。在环境环境中，这种能量吸收的增加可能会转化为金字塔湖和其他受野火影响的地表水中表层海水升温的增加。
Black carbon (BC), pyrogenic residues resulting from the incomplete combustion of organics, are liberated from wildfires at high rates. Subsequent introduction to aqueous environments via atmospheric deposition or overland flow results in the formation of a dissolved fraction, called dissolved black carbon (DBC). As wildfire frequency and intensity increases along with a changing climate, it becomes imperative to understand the impact a concurrent increase in DBC load might have to aquatic ecosystems. In the atmosphere BC stimulates warming by absorbing solar radiation, and similar processes may occur with surface waters that contain DBC. In this work we investigated whether the addition of environmentally relevant levels of DBC could impact surface water heating dynamics in experimental settings. DBC was quantified at multiple locations and depths in Pyramid Lake (NV, USA) during peak fire season while two large, proximal wildfires burned. DBC was detected in Pyramid Lake water at all sampled locations at concentrations (3.6–18 ppb) significantly higher than those reported for other large inland lakes. DBC was positively correlated (R2= 0.84) with chromophoric dissolved organic matter (CDOM) but not bulk dissolved or total organic carbon (DOC, TOC), suggesting that DBC is a significant component of the optically active organics in the lake. Subsequent lab-based experiments were conducted by adding environmentally relevant levels of DBC standards to pure water, exposing the system to solar spectrum radiation, and creating a numerical model of heat transfer based on observed temperatures. The addition of DBC at environmentally relevant orders of magnitude caused reductions to shortwave albedo when exposed to the solar spectrum, which resulted in 5–8 % more incident radiation being absorbed by water and changes to water heating dynamics. In environmental settings, this increase in energy absorption could translate to increased heating of the epilimnion in Pyramid Lake and other wildfire-impacted surface waters.