Ash Leachate Research Articles

Chemical characterization and mobility of metal species in fly ash–water system

The present investigation was conducted to study the leaching characteristics, speciation and fractionation of trace and major elements from fly ash. Five liquid-to-solid ratios (L/S) were selected, ranging from 0.5 to 1. The releasing of trace and major elements from fly ash increased as L/S ratios increased or over time (at pH = 2.88). γ-Al(OH)3, Cd3(PO4)2, azurite, jarosite, MnCO3, Pb(OH)2, quartz (SiO2) and ZnCO3 are the solid phases that control Al, Cd, Cu, Fe, Mn, Pb, Si and Zn activities in fly ash leachates. The sequential chemical extraction tests showed that Al, Cd, Cu, Fe, Mn, Pb, Si and Zn were mainly present in the last three fractions, which were Fe–Mn oxides, organics and residual fractions and their leachability could be well-controlled in common natural environment. According to risk assessment code (RAC); Cd, Cu, Mn and Pb show a medium risk, while Zn and Fe shows low risk level, but Al and Si are considered safe to our environment.

Chemical, Leaching, and Toxicity Characteristics of Coal Ashes from Circulating Fluidized Bed of a Philippine Coal-Fired Power Plant

Characterization of the coal ash from a typical coal-fired circulating fluidized bed (CFB) power plant in the Philippines was done by studying physical and chemical properties as well as toxic elements content from Semirara and Indonesian fly and bottom ashes. Laboratory-scale experiment was carried out using serial batch leaching procedure (SBLP) to determine the leaching behavior of toxic elements from coal ashes and to mimic the environmental condition using sulfuric acid. From the X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses, the main compound present is CaO which makes the coal ash alkaline in nature. Moreover, SiO2, Fe3O4, and other trace minerals are also present. Also, toxicity characterization leaching procedure (TCLP) shows that more than 99 % of chromium and arsenic remain in the coal ashes matrix. The results of the chemical analysis of eluates deduced by the application of standard leaching tests according to TCLP method indicated that hazardous elements such as heavy metals and metalloids contained in fly and bottom ashes could potentially be transferred to the liquid phase. According to the Microtox analysis, the bottom ashes are less toxic than fly ashes due to the vaporization of toxic elements during the combustion and their subsequent adsorption on the surface of fly ashes. Furthermore, leaching of chromium from the coal ash samples was significantly affected by initial pH of the leachant adjusted with sulfuric acid. The highest leaching rate was reached using the combined condition of pH of 8, contact time of 8 h, and L/S of 5. With these conditions, the leaching rate of chromium from SBA is 0.059, from SFA is 0.070, from IBA is 0.054, and from IFA is 0.06 g Cr/g of ash per hour. Based on literature, the results are relatively comparable.

Characteristics of distinct ash flows in a biomass thermal power plant with bubbling fluidised bed combustor

Characteristics of biomass used as fuel and distinct ash flows in a thermal power plant with BFBC (bubbling fluidised bed combustion) technology were studied. An integrated approach involving chemical composition, microscopy analysis, mineralogy, and thermal behaviour were used to characterize the ash. The ashes have a low unburned content, typically below 3 wt.% (dry basis), with higher values in ash from the electrostatic precipitator. The chemical element present in higher concentration in the several ash flows is Si (>20 wt.%, dry basis). The fly ash from the electrostatic precipitator are enriched in heavy metals when compared to other ash, and Zn is the heavy metal found in higher concentration (but <225 ppm wt., dry basis), followed by Cr, Pb, Cu and Ni in decreasing order of abundance. The distinct ash produce leaching solutions with pH values in range 11.9–12.8, and conductivity in the range 4.7–19.5 mS/cm, with higher values in ash from electrostatic precipitator. Ca is the element in higher concentration in the ash leachates, followed by K, Na and Cl. The concentration of heavy metals in the leachates is relatively low. The biomass quality influences the ash characteristics, and an appropriate management of biomass and ash is need to improve the performance of thermal power plants.

Phototrophic culture of Chlorella sp. using charcoal ash as an inorganic nutrient source

Although several studies have recognized the suitability of employing ashes as a component of a culture medium or fertilizer, the number of these studies remains limited. The use of biomass ash as a nutrient source for algal culture is an unexplored research topic that should be investigated to analyse the possibility of reducing the costs associated with commercial microalgae culture.In this study, biomass ash from charcoal was used as a source of nutrients for the cultivation of Chlorella sp., and two alternative processes for nutrient supply were studied. First, various culture media containing the leachate stock solution from solid ash at different concentrations were prepared. Second, different amounts of solid ash were added directly to the culture media. The results indicated that the direct use of biomass ash mixed in water enables the formation of a more suitable medium compared with Guillard's f/2 medium because it promotes faster cell growth and higher biomass productivity. The higher biomass productivities were reached over the same period compared with those achieved with the culture media based on biomass ash leachates. Moreover, the nutrients in the media containing ash leachates are sufficient to maintain cell growth rates and biomass productivities that are comparable to those achieve with Guillard's f/2 medium.

Immobilization and volume reduction of heavy metals in municipal solid waste fly ash using nano-size calcium and iron-dispersed reagent

This study was conducted to examine the synthesis and application of novel nano-size calcium/iron-based composite material as an immobilizing and separation treatment of the heavy metals in fly ash from municipal solid waste incineration. After grinding with nano-Fe/Ca/CaO and with nano-Fe/Ca/CaO/[PO4], approximately 30 wt% and 25 wt% of magnetic fraction fly ash were separated. The highest amount of entrapped heavy metals was found in the lowest weight of the magnetically separated fly ash fraction (i.e., 91% in 25% of treated fly ash). Heavy metals in the magnetic or nonmagnetic fly ash fractions were about 98% and 100% immobilized, respectively. Additionally, scanning electron microscopy combined with energy-dispersive X-ray spectrometry (SEM-EDS) observations indicate that the main fraction of enclosed/bound materials on treated fly ash includes Ca/PO4-associated crystalline complexes. After nano-Fe/Ca/CaO/[PO4] treatment, the heavy metal concentrations in the fly ash leachate were much lower than the Japan standard regulatory limit for hazardous waste landfills. These results appear to be extremely promising. The addition of a nano-Fe/Ca/CaO/PO4 mixture with simple grinding technique is potentially applicable for the remediation and volume reduction of fly ash contaminated by heavy metals.Implications: After grinding with nano-Fe/Ca/CaO and nano-Fe/Ca/CaO/[PO4], approximately 30 wt% and 25 wt% of magnetic fraction fly ash were separated. The highest amount of entrapped heavy metals was found in the lowest weight of the magnetically separated fly ash fraction (i.e., 91% in 25% of treated fly ash), whereas heavy metals either in the magnetic or nonmagnetic fly ash fractions were about 98% and 100% immobilized. These results appear to be very promising, and the addition of nano-Fe/Ca/CaO/PO4 mixture with simple grinding technique may be considered potentially applicable for the remediation and volume reduction of contaminated fly ash by heavy metals.

Solvent extraction separation of copper and zinc from MSWI fly ash leachates

Fly ash from combustion of municipal solid waste (MSW) contains significant amounts of metals, some of which are valuable and some of which are potentially toxic. This type of ash is most often stabilized and landfilled which means that the metals will be difficult to reclaim at a later stage. In recent years efforts have been made to develop feasible methods to recover selected metals, such as Zn, from MSW fly ash. If this would be possible, a significant amount of valuable metals could be re-inserted in the industrial material loops.This paper describes the development and evaluation of a process for recovery of Cu and Zn from MSW combustion fly ash based on hydrochloric acid leaching followed by two solvent extraction processes, one for each metal. The separation of Cu from the acid leachate was done using an aldoxime extractant, LIX860N-I, in kerosene and a mixture of phosphine oxides, Cyanex 923, also in kerosene, was used for extraction of Zn from the Cu-depleted aqueous phase. The extraction of Cu was selective, but a significant amount of other metals, such as Fe and Pb, were co-extracted together with Zn. It was shown that it is possible to decrease the contamination of Fe by using a suitable concentration of nitric acid solution for stripping or by removing the contaminating metals through cementation.The suggested process was tested for two MSW combustion fly ashes in laboratory scale experiments and gave Cu yields of 69–87% and Zn yields of 75–80% based on the contents in the ash.

Evaluation of interactions between soil and coal fly ash leachates using column percolation tests

The aim of this work was the assessment of the environmental impact of different origin fly ashes with regard to their final disposal. The experimental procedure included the performance of single column tests and column tests of fly ash and soil in series. The appraisal of the potential environmental hazards was implemented using physicochemical analyses and bioassays. Two different fly ash samples were examined, one fly ash produced from the combustion of sub-bituminous coal (CFA) and one fly ash produced from the combustion of lignite (LFA). Single column percolation tests were performed according to NEN 7343 protocol, while fly ash/soil experiments were conducted incorporating slight modifications to this protocol. The study focused on the release of metals Ba, Cr, Cu, Mo, Se and Zn and the ecotoxic behavior of leachates on crustacean Daphnia magna and bacteria Vibrio fischeri. The infiltration of the leachates of both fly ashes through soil affected considerably their leaching profile. The transport of Cu and Zn was facilitated by the dynamic leaching conditions and influenced by the pH of the leachates. Moreover, the release and bioavailability of Cr, Cu and Zn was probably altered during the infiltration experiments and organisms’ response was not always correlated with the concentration of metals. Nevertheless, the results are signalling that possible manipulations and final disposal of fly ash should be considered when environmental threats are investigated.

Residual organic matter and microbial respiration in bottom ash: Effects on metal leaching and eco-toxicity.

A common assumption regarding the residual organic matter, in bottom ash, is that it does not represent a significant pool of organic carbon and, beyond metal-ion complexation process, it is of little consequence to evolution of ash/leachate chemistry. This article evaluates the effect of residual organic matter and associated microbial respiratory processes on leaching of toxic metals (i.e. arsenic, copper, chromium, molybdenum, nickel, lead, antimony and zinc), eco-toxicity of ash leachates. Microbial respiration was quantified with help of a respirometric test equipment OXITOP control system. The effect of microbial respiration on metal/residual organic matter leaching and eco-toxicity was quantified with the help of batch leaching tests and an eco-toxicity assay - Daphnia magna. In general, the microbial respiration process decreased the leachate pH and eco-toxicity, indicating modification of bioavailability of metal species. Furthermore, the leaching of critical metals, such as copper and chromium, decreased after the respiration in both ash types (fresh and weathered). It was concluded that microbial respiration, if harnessed properly, could enhance the stability of fresh bottom ash and may promote its reuse.

Mixing of Acid Rock Drainage with Alkaline Ash Leachates: Formation of Solid Precipitates and pH-Buffering

Three metal-rich, acidic mine waters (from Bersbo and Ljusnarsberg, Sweden) were mixed with alkaline fly ash leachates in various proportions, representing a pH titration. Changes in pH and the loss of metals in solution due to precipitation of solid phases were tracked. Mineral equilibria and changes in pH and alkalinity were simulated using the geochemical code PHREEQC and the MINTEQv4 database, and the measured and simulated pH responses were compared. The formation of solid precipitates corresponded to fairly well-defined pH-buffering regions, reflecting the mine water compositions (notably the levels of Fe, Al, and Mn). Zn precipitation had a distinct buffering effect at near-neutral pH for the mine waters not dominated by iron. The formation of solid Mg phases (carbonate, as well as hydroxide) was indicated at high pH (above 9), but not formation of solid Ca phases, despite high sulfate levels. The phases that precipitated were various amorphous mixtures, mostly of the metals Fe, Al, Mn, Zn, and Mg. For the Fe-rich mine water, pH was poorly simulated with a simple MIX model, while alkalinity predictions agreed reasonably well with measured data. For the Al-rich mine waters, the simulated pH responses agreed well with the measurements. In an additional step, geochemical simulations were performed where selected proxy phases for major elements were forced to precipitate; this significantly improved the pH and alkalinity predictions. This approach may be more efficient than performing mixing experiments and titrations.

Aluminum extraction from coal ash by a two-step acid leaching method

To improve aluminum extraction efficiency, a two-step acid leaching process was proposed to dissolve aluminum and aluminum-bearing crystals with sulfuric acid. The first leaching residue (FLR) was obtained through direct leaching of coal ash with sulfuric acid. After roasting a mixture of the FLR and sodium carbonate, the aluminum-bearing crystals in FLR were completely destroyed while sodium silicate was generated. Then the roasted products were leached with water to dissolve the sodium carbonate. X-ray diffraction (XRD) analysis indicated that the water leaching residues (WLR) mainly contained the amorphous phase, which allowed easy aluminum extraction in the second leaching step. In the first leaching test with 10 mol/L sulfuric acid at 120 °C in 2 h and a solid to liquid ratio (S/L) of 1:2, aluminum dissolution from raw coal ash reached 81.72%. In the second leaching step with 5 mol/L sulfuric acid, the aluminum dissolutions from WLR were 87.31% at 20 °C and 99.06% at 100 °. Total aluminum dissolutions were more than 97%. Moreover, the leaching process produced two by-products, sodium silicate solution and amorphous silicon dioxide, which contained nearly all the silicon from the coal ash.

Treatment of Industrial Brass Wastes for the Recovery of Copper and Zinc

A combined pyro-hydrometallurgical treatment processes involving leaching, cementation, electrowinning, and melting have been applied to industrial brass wastes, brass ash, and flue dust to recover copper and zinc. In the first stage, the effects of leach parameters on metal recovery ratio were studied. Almost all zinc was dissolved from brass wastes in conditions of 1 M H2SO4, 120 min, 60°C, 400 rpm stirring speed, and 1/10 solid liquid ratio. Negligible amount of copper was also dissolved in the same conditions and this copper could be precipitated by cementation. Pure zinc of 99.4% and 99.5% were produced by electrowinning of purified brass ash and flue dust leach solutions, respectively. Leach residue containing high amount of copper was melted with various fluxes and more than 99% of copper recovery ratio was achieved.

Recovery of uranium, hafnium and zirconium from petroleum ash leach liquor

We investigated the optimum adsorption conditions of uranium, hafnium and zirconium elements from petroleum fly ash leach liquor using Dowex 1×8 as a strong basic anion exchange.

Co-gasification of sewage sludge and woody biomass in a fixed-bed downdraft gasifier: Toxicity assessment of solid residues

As the demand for fossil fuels and biofuels increases, the volume of ash generated will correspondingly increase. Even though ash disposal is now strictly regulated in many countries, the increasing volume of ash puts pressure on landfill sites with regard to cost, capacity and maintenance. In addition, the probability of environmental pollution from leakage of bottom ash leachate also increases. The main aim of this research is to investigate the toxicity of bottom ash, which is an unavoidable solid residue arising from biomass gasification, on human cells in vitro. Two human cell lines i.e. HepG2 (liver cell) and MRC-5 (lung fibroblast) were used to study the toxicity of the bottom ash as the toxins in the bottom ash may enter blood circulation by drinking the contaminated water or eating the food grown in bottom ash-contaminated water/soil and the toxic compounds may be carried all over the human body including to important organs such as lung, liver, kidney, and heart. It was found that the bottom ash extract has a high basicity (pH=9.8–12.2) and a high ionic strength, due to the presence of alkali and alkaline earth metals e.g. K, Na, Ca and Mg. Moreover, it also contains concentrations of heavy metals (e.g. Zn, Co, Cu, Fe, Mn, Ni and Mo) and non-toxic organic compounds. Although human beings require these trace elements, excessive levels can be damaging to the body. From the analyses of cell viability (using MTS assay) and morphology (using fluorescence microscope), the high toxicity of the gasification bottom ash extract could be related to effects of high ionic strength, heavy metals or a combination of these two effects. Therefore, our results suggest that the improper disposal of the bottom ash wastes arising from gasification can create potential risks to human health and, thus, it has become a matter of urgency to find alternative options for the disposal of bottom ash wastes.

English

The production of ‘dawadawan botso’ a local condiment produced by traditional uncontrolled fermentation, in Nigeria and other parts of Africa is usually based on experience rather than standard measurements. This work was aimed at evaluating the effect of substrate ( Hibiscus sabdariffa seeds) and ash leachate on the chemical composition, amino acid profile and the taste of ‘dawadawan botso.' Locally prepared ‘dawadawan botso’ was collected from a local producer and its quality was compared to that prepared in the laboratory under optimized conditions. The ash leachate was standardized by dissolving known masses of ash in a fixed volume of water. The pH of the ash leachate was determined and then added to the substrate before the second fermentation. The pH of the unfermented, fermented H. sabdariffa and the ‘dawadawan botso’ were determined using a pH meter. Determination of the proximate composition, mineral and amino acid profile were done by AOAC method. The results were analyzed statistically using ANOVA and the post-hoc test using Duncan multiple range test (DMRT) for means that were significantly different from each other. Paired sample T- test was also done to test for the significance between groups at P<0.05 using SPSS. The results show that the volume of leachate decreased (385 ml/100 g ash to 144 ml/250 g ash) with increasing pH (13.60 to 13.70) as the mass of ash increased. Proximate analyses showed that carbohydrates were the highest followed by proteins and least was lipids. Potassium (K) and sodium (Na) were the major minerals; magnesium (Mg), phosphorus (P) and calcium (Ca) were insignificant compared to the later. The pH of the substrate decreased after second fermentation for all standards and also decreased as mass of substrate increased. The following amino acids; glutamic, aspartic and methionine were observed to decrease with increasing mass of substrate. Fermentation increased the value of total amino acids in substrate. Taste analyses indicated that monosodium glutamate-like taste was dominant, followed by bitter and sweet, respectively for all samples analyzed. Keywords: Ash , Hibiscus sabdariffa, “ dawadawan botso”, amino acid profile, proximate composition. African Journal of Biotechnology , Vol 13(31) 3628-3637

Bacterial Treatment and Metal Characterization of Biomedical Waste Ash

Biomedical waste ash generated due to the incineration of biomedical waste contains large amounts of heavy metals and polycyclic aromatic hydrocarbons (PAHs), which is disposed of in regular landfills, and results in unfavorable amounts of hazardous materials seeping into the ground and may pollute surface water and groundwater. Therefore, it is essential to remove the toxicity of ash before disposal into landfills or reutilization. Environmental characteristic analysis of BMW ash showed increased hardness (1320 mg/L) and chloride (8500 mg/L) content in leachate compared to World Health Organization (WHO) and Environment Protection Agency (EPA) guidelines for drinking water (hardness, 300 mg/L; chloride, 250 mg/L). The alkalinity and pH of the ash leachate were 400 mg/L and 8.35, respectively. In this paper, study was carried out to investigate the metal tolerance level of bacterial isolates isolated from soil. The isolate Bacillus sp. KGMDI can tolerate up to 75 mg/L of metal concentration (Mn, Mo, Cr, Fe, Cu, and Zn) in enriched growth medium. This shows that the isolated culture is capable of growing in presence of high concentration of heavy metals and acts as potential biological tool to reduce the negative impact of BMW ash on the environment during landfilling.

Volcanic ash leachate compositions and assessment of health and agricultural hazards from 2012 hydrothermal eruptions, Tongariro, New Zealand

After almost 80years of quiescence, the upper Te Maari vent on Mt. Tongariro erupted suddenly at 2352h (NZ time) on 6 August 2012. The short-lived hydrothermal eruption distributed a fine ash of minor volume (~5×105m3) over 200km from source. The threat of further eruptions prompted an investigation of the possible health and agricultural impacts of any future eruptions from this volcano, particularly since the most recent large-scale ash falls in New Zealand in 1995–1996 had generated significant agricultural problems, including livestock deaths. Deposited ash was sampled between 5 and 200km from the volcano as soon as possible after the eruption. Two sub-lobes of ash were identified from different vent areas and displayed subtly different leaching properties. The first was an initial small lobe directed NNE, likely formed from drifting low-level clouds associated with the initial lateral explosive blast and surges. The main fall lobe, directed eastward, was sourced from a short-lived vertical plume that rose up to c. 8km. Ash from the initial fall lobe had higher concentrations of F and Al, in single-step leaches as well as in the totals of three, sequential extractions. Further, the initial lobe showed a higher proportion of soluble F and Al extracted in the first leach, compared to totals. A linear relationship between concentrations of Al and F in single leaches from the 6 August eruption was highly significant (Pearson correlation coefficient r=0.987 for 1:20 leaching ratios and r=0.971 for 1:100), suggesting the presence of soluble alumino-fluoride complexes (AlFx+3−x). An even more significant 1:1 ratio is displayed for the largest concentration leached ions of Ca and SO4, which correspond to the presence of crystalline gypsum throughout the newly excavated hydrothermal system. Although no fresh magma was erupted in this event, a shallow intrusion prior to the hydrothermal explosion apparently provided significant contents of volcanic gas that was dissolved within the hydrothermal fluids and adhering to ejected particles. This and the ubiquitous presence of gypsum dominated the soluble components of these ash deposits leading to a complex leaching profile.The leaching study carried out here showed that agricultural and human health hazard assessment (particularly of F and S) is not straightforward, particularly because F solubility may be complex and not well characterised by simple leaching studies. In the case of S, which is agriculturally important, saturation effects are apparent using normal leaching protocols and also imply a need for modification of standard methods.

Nanofiltration for the recovery of phosphorus — Development of a mass transport model

Nanofiltration is a possible separation technology for phosphorus recycling from sewage sludge or sewage sludge ash. Nanofiltration can be applied for this purpose in combination with a low pressure wet oxidation or acidic hydrolysis of sewage sludge or leaching of sewage sludge ash. The feed of the nanofiltration in this application is in the pH range of 1.5 to 3 and contains phosphoric acid, sulphuric acid as well as metal ions which should be rejected. This paper presents experimental data and multi-ion transport modelling. The model is based on the solution diffusion model with permeability coefficients as the only input parameters. For several simplified synthetic solutions permeability coefficients could be successfully fitted. By interpolation of the parameters as functions of pH and concentration in the nanofiltration feed, retentions could be calculated for additional compositions. A validation with real solutions obtained from sewage sludge was performed.

Mechanisms Underpinning the Mobilization of Iron and Magnesium Cations from Victorian Brown Coal Fly Ash

This paper reported the leaching of Yallourn brown coal fly ash uniquely rich in magnesioferrite (MgFe2O4) using hydrochloric acid, by varying acid concentration, liquid-to-solid (L/S) ratio, temperature, and time, to understand the mechanisms underpinning the extraction of iron and magnesium. Results indicate that Yallourn fly ash is composed of a densely packed, crystalline ash matrix, mainly in the form of MgFe2O4 and maghemite (γ-Fe2O3). Thermal cleaving at 100 °C and above liberates embedded octahedrally coordinated Fe3+, a controlling step for the leaching process. Increments from 100 to 200 °C did little to enhance extraction of Fe and Mg in single-stage leaching. Except at 70 °C, the thermal decomposition for the elution of both metals was complete within 1 min, while increasing the L/S ratio and acid concentration had negligible influence. The application of two-stage leaching gave protons a larger driving force to access embedded unreacted species. Subsequently, the extraction yields of both Fe ...

Recycling of washed olive pomace ash for fired clay brick manufacturing

Milled or micronized washed olive pomace ash was used to replace different amounts (5 and 10wt%) of clay in brick manufacture. The properties of these bricks were compared to conventional products following standard procedures. Bricks formed with ash showed a decrease of 0.13–0.16W/mK in thermal conductivity. With a minimum bulk density and bending strength of 1790–1810kgm−3, and 10–12Nmm−2, respectively, fired bricks fulfil standard requirements for clay masonry units. Milled ash performs better than micronized ash. The ash leachate is a valuable source of potassium for the manufacture of fertilizers.

Contribution of forest fire ash and plant litter decay on stream dissolved composition in a sub-humid tropical watershed (Mule Hole, Southern India)

The current understanding of wildfire effects on water chemistry is limited by the quantification of the elemental dissolution rates from ash and element release rate from the plant litter, as well as quantification of the specific ash contribution to stream water chemistry. The main objective of the study was to provide such knowledge through combination of experimental modelling, field data and end-member mixing analysis (EMMA) of wildfire impact on a watershed scale. The study concerns watershed effects of fire in the Indian subcontinent, a region that is typically not well represented in the fire science literature. In plant litter ash, major elements are either hosted in readily-soluble phases (K, Mg) such as salts, carbonates and oxides or in less-soluble carrier-phases (Si, Ca) such as amorphous silica, quartz and calcite. Accordingly, elemental release rates, inferred from ash leaching experiments in batch reactor, indicated that the element release into solution followed the order K>Mg>Na>Si>Ca. Experiments on plant litter leaching in mixed-flow reactor indicated two dissolution regimes: rapid, over the week and slower over the month. The mean dissolution rates at steady-state (Rss) indicated that the release of major elements from plant litter followed the order Ca>Si>Cl>Mg>K>Na. Rss for Si and Ca for tree leaves and herbaceous species are similar to those reported for boreal and European tree species and are higher than that from the dissolution of soil clay minerals. This identifies tropical plant litters as important source of Si and Ca for tropical surface waters. In the wildfire-impacted year 2004, the EMMA indicated that the streamflow composition (Ca, K, Mg, Na, Si, Cl) was controlled by four main sources: rainwater, throughfall, ash leaching and soil solution. The influence of the ash end-member was maximal early in the rainy season (the two first storm events) and decreased later in the rainy season, when the stream was dominated by the throughfall end-member. The contribution of plant litter decay to the streamwater composition for a year not impacted by wildfire is significant with estimated solute fluxes originating from this decay greatly exceed, for most major elements, the annual elemental dissolved fluxes at the Mule Hole watershed outlet. This highlighted the importance of solute retention and vegetation back uptake processes within the soil profile. Overall, the fire increased the mobility and export of major elements from the soils to the stream. It also shifted the vegetation-related contribution to the elemental fluxes at the watershed outlet from long-term (seasonal) to short-term (daily to monthly).