Wildfire effects on extractable elements in ash from aPinus pinasterforest in Portugal

Abstract

The aim of this work is to study the effects of a wildfire on water-extractable elements in ash from a Pinus pinaster forest located in Portugal. The pH, electrical conductivity (EC), calcium (Ca 2+ ), magnesium (Mg 2+ ), sodium (Na + ), potassium (K + ), sodium and potassium adsorption ratio (SPAR), aluminium (Al 3+ ), manganese (Mn 2+ ), iron (Fe 2+ ), zinc (Zn 2+ ), sulphur (S), silica (Si) and phosphorous (P) were analysed in ash sampled from a sloped area burned in a wildfire and from litter from a contiguous unburned area, with similar morphological conditions. The results showed that ash leachates had higher pH and EC, and were significantly richer in water-extractable Ca 2+ , Mg 2+ , Na + , K + , SPAR, S and Si and significantly poorer in water-extractable Al 3+ , Fe 2+ , Mn 2+ and Zn 2+ than litter solutions. No significant differences were observed in water-extractable P. The fire changed the ash solute chemistry compared with the unburned litter and increased the sample variability of nutrient distribution with potential implications for plant recovery.Comparisons made with untransformed data (1), and Ln transformed data (2), and with Mann-Whitney U test due to lack of normality after Ln and Box-Cox data transformations (3). n.s means that differences are not significant at p < 0.05, electrical conductivity is in mS/cm and extractable elements are in mg/l. SD, standard deviation; min, minimum; max, maximum; CV%, coefficient of variation; SPAR, sodium and potassium adsorption ratio. 3684 P. PEREIRA ET AL.

Remote Sensing Techniques to Assess Post-Fire Effects at the Hillslope and Sub-Basin Scales via Multi-Scale Model

“…Since hillslope soils are affected by the impacts of wildfires (Dlapa et al, 2013;Pereira et al, 2014;Dlapa et al, 2015, Tessler et al, 2015, mainly by erosion, rates, and general heat impact on the soil (Novara et al, 2013;Keesstra et al, 2014;Hedo et al, 2015;Pereira et al, 2015). Moreover, the ash and top-soil in a post-fire environment are exposed to changes introduced by the rainfall and wind (two main erosion factors).…”

Interpretation of the Factors Defining Groundwater Quality of the Site Subjected to the Wildfire of 2007 in Ilia Prefecture, South-Western Greece

“…Metals are of major importance due to their high toxicity, their long life and their tendency to bioaccumulate in aquatic systems [6]. The severity of wildfires affects the type and amount of eluted elements, while the Sodium Adsorption Ratio (SAR) is higher for intense wildfires [4]. Moreover, in Mediterranean areas, as the new hydrological year begins, rainfalls are usual during the months following the period of wildfires.…”

“…According to Pereira et al [4], Ca, S, Mg, K, and Na prevailed in soil water at an affected P. pinaster forest in Portugal. Kučerová et al [7] found high concentrations of P, N in a Pinus rotundata forest in the Czech Republic, three years after the fire.…”

“…According to Earl and Blinn [8], high concentrations of NH 4 , N, SRP, and K, and increased alkalinity values, lasted for thirteen months at an affected area of P. halepensis forest in the Southwestern USA, both in nearby streams and in streams far away from the affected area.…”

“…There have been several publications over the current decade that report on the impacts of the produced ash on soil and soil water, mentioning the need for the potential impacts on groundwater to be also examined. According to several laboratory-conducted studies that simulated the combustion of biomass, such as P. halepensis, ash is alkaline (pH = 9-13.5), rich in elements, such as Ca, Mg, Na, K, Al, Fe and P, S and trace elements, such as Mn and Zn [2][3][4]. The most prevailing elements after the wildfires were reported to be Ca, Mg, K, Si, P [5], Mn, Zn, V, Pb, Cr, and Cu [6].…”