Forest Fire Effects on Mercury Deposition in the Boreal Forest

Witt, Emma L.; Kolka, Randall K.; Nater, Edward A.; Wickman, Trent R.

doi:10.1021/es802634y

Cited by 45 publications

(56 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…4), which may reflect atmospheric deposition of Hg p prior to erosion of sediments. Witt et al (2009) reported total Hg levels in precipitation significantly increased following fires (samples collected 3-47 days postburn). Since Hg p is readily scavenged by rain, these results suggested Hg released from vegetation and soil during a fire was deposited through wet deposition of Hg p .…”

Section: Atmospheric Deposition Of Hg Pmentioning

confidence: 97%

The impact of over 100 years of wildfires on mercury levels and accumulation rates in two lakes in southern California, USA

et al. 2009

View full text Add to dashboard Cite

In southern California, USA, wildfires may be an important source of mercury (Hg) to local watersheds. Hg levels and Hg accumulation rates were investigated in dated sediment cores from two southern California lakes, Big Bear Lake and Crystal Lake, located approximately 40-km apart. Between 1895 and 2006, fires were routinely minimized or suppressed around Big Bear Lake, while fires regularly subsumed the forest surrounding Crystal Lake. Mean Hg concentrations and mean Hg accumulation rates were significantly higher in Crystal Lake sediments compared to Big Bear Lake sediments (Hg levels: Crystal Lake 220 ± 93 ng g -1 , Big Bear Lake 92 ± 26 ng g -1 ; Hg accumulation: Crystal Lake 790 ± 1,200 lg m -2 year -1 , Big Bear 240 ± 54 lg m -2 year -1 ). In Crystal Lake, the ratio between post-1965 and pre-1865 Hg concentrations was 1.1, and several spikes in Hg levels occurred between 1910 and 1985. Given the remote location of the lake, the proximity of fires, and the lack of point sources within the region, these results suggested wildfires (rather than industrial sources) were a continuous source of Hg to Crystal Lake over the last 150 years.

show abstract

Section: Atmospheric Deposition Of Hg Pmentioning

confidence: 97%

The impact of over 100 years of wildfires on mercury levels and accumulation rates in two lakes in southern California, USA

et al. 2009

View full text Add to dashboard Cite

show abstract

“…Combustion studies in laboratories on conifer and deciduous litter have indicated that nearly the entire Hg pool (>98%) is emitted back to the atmosphere, with little left behind in ash (Friedli et al, 2003). Although the bulk of the Hg emitted during wildfires is in elemental form (Hg 0 ) that will ultimately be deposited outside the watershed and potentially far from the site of the fire, about 13% of the Hg emitted during wildfires is in particulate form (Friedli et al, 2003), which has the potential to be deposited locally (Witt et al, 2009). In our study, 72% of the Hg pool was lost from the forest floor, 7% from the 0-to 10-cm soil depth and 10% from the 10-to 20-cm soil depth.…”

Section: S63mentioning

confidence: 99%

“…Hence, volatilization of C and associated THg as a result of fire could lead to long-term decreases in Hg in the aquatic food chain as THg is removed from the watershed; however, short-term impacts are less clear. Other studies in northern Minnesota have indicated that fire leads to enhanced local deposition (Witt et al, 2009) that, in the short term, has the potential to bioaccumulate in the food chain (Kelly et al, 2006). Others have found little or no change in accumulation in aquatic biota following fire Carignan, 1999, 2000;Allen et al, 2005).…”

mentioning

confidence: 99%

Post‐Fire Comparisons of Forest Floor and Soil Carbon, Nitrogen, and Mercury Pools with Fire Severity Indices

Kolka

Sturtevant

Townsend

et al. 2014

Soil Science Soc of Amer J

View full text Add to dashboard Cite

Forest fires are important contributors of C, N, and Hg to the atmosphere. In the fall of 2011, a large wildfire occurred in northern Minnesota and we were able to quickly access the area to sample the forest floor and mineral soil for C, N, and Hg pools. When compared with unburned reference soils, the mean loss of C resulting from fire in the forest floor and the upper 20 cm of mineral soil was 19.3 Mg ha−1, for N the mean loss was 0.17 Mg ha−1, and for Hg the mean loss was 9.3 g ha−1. To assess the influence of fire severity on the forest floor and mineral soils, we used an established method that included a soil burn severity index and a tree burn severity index with a gradient of severity classes. It was apparent that the unburned reference class had greater forest floor C, N, and Hg pools and higher C/N ratios than the burned classes. The C/N ratios of the 0‐ to 10‐ and 10‐ to 20‐cm mineral soils in the unburned reference class were also greater than in the burned classes, indicating that a small amount of C was lost and/or N was gained, potentially through leaching unburned forest floor material. However, with a couple of exceptions, the severity classes were unable to differentiate the forest floor and mineral soil impacts among soil burn and tree burn severity indices. Developing burn severity indices that are reflective of soil elemental impacts is an important first step in scaling ecosystem impacts both within and across fire events.

show abstract

“…Comparison to other studies suggests that the vast majority of this loss is to the atmosphere, leading to both long-range transport and localized increases in atmospheric mercury and deposition in other watersheds. 31 Although it is likely that these disturbances increase the hydrologic mobility of Hg from soils, this flux is most likely small (10−20%) compared to fluxes to the atmosphere. Because the combination of blowdown, salvage logging, and wildfire dramatically decreased both THg concentrations and pools, it may take decades, perhaps centuries, for Hg to accumulate to predisturbance levels, 30 which could decrease Hg levels in nearby aquatic biota over this time period.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Singular and Combined Effects of Blowdown, Salvage Logging, and Wildfire on Forest Floor and Soil Mercury Pools

Mitchell

Kolka

Fraver

2012

Environ. Sci. Technol.

Self Cite

View full text Add to dashboard Cite

A number of factors influence the amount of mercury (Hg) in forest floors and soils, including deposition, volatile emission, leaching, and disturbances such as fire. Currently the impact on soil Hg pools from other widespread forest disturbances such as blowdown and management practices like salvage logging are unknown. Moreover, ecological and biogeochemical responses to disturbances are generally investigated within a single-disturbance context, with little currently known about the impact of multiple disturbances occurring in rapid succession. In this study we capitalize on a combination of blowdown, salvage logging and fire events in the sub-boreal region of northern Minnesota to assess both the singular and combined effects of these disturbances on forest floor and soil total Hg concentrations and pools. Although none of the disturbance combinations affected Hg in mineral soil, we did observe significant effects on both Hg concentrations and pools in the forest floor. Blowdown increased the mean Hg pool in the forest floor by 0.76 mg Hg m(-2) (223%). Salvage logging following blowdown created conditions leading to a significantly more severe forest floor burn during wildfire, which significantly enhanced Hg emission. This sequence of combined events resulted in a mean loss of approximately 0.42 mg Hg m(-2) (68% of pool) from the forest floor, after conservatively accounting for potential losses via enhanced soil leaching and volatile emissions between the disturbance and sampling dates. Fire alone or blowdown followed by fire did not significantly affect the total Hg concentrations or pools in the forest floor. Overall, unexpected consequences for soil Hg accumulation and by extension, atmospheric Hg emission and risk to aquatic biota, may result when combined impacts are considered in addition to singular forest floor and soil disturbances.

show abstract

Forest Fire Effects on Mercury Deposition in the Boreal Forest

Cited by 45 publications

References 25 publications

The impact of over 100 years of wildfires on mercury levels and accumulation rates in two lakes in southern California, USA

The impact of over 100 years of wildfires on mercury levels and accumulation rates in two lakes in southern California, USA

Post‐Fire Comparisons of Forest Floor and Soil Carbon, Nitrogen, and Mercury Pools with Fire Severity Indices

Singular and Combined Effects of Blowdown, Salvage Logging, and Wildfire on Forest Floor and Soil Mercury Pools

Contact Info

Product

Resources

About