Simulated temperatures of forest fires affect water solubility in soil and litter
4
Citation
72
Reference
10
Related Paper
Citation Trend
Abstract:
As wildfires are of increasing concern in a warming world, there is a need to understand how fire temperatures affect solute concentrations of forest litter and soils in drinking water catchments. In addition, the concentrations are expected to be affected by time since the previous fire. We sampled soil and litter from recently (2 months) and less recently (4.5 years) burnt sites from jarrah forest in SW Australia. The samples were heated at 250°C, 350°C, and 500°C for 30min followed by leaching to determine solute compositions at these temperatures and in unburnt samples. At 250°C–350°C, we found increased concentrations of manganese (Mn), arsenic (As), total phosphorus (TP), phosphate (PO43-), ammonia (NH4+), potassium (K), calcium (Ca), mangesium (Mg), cobalt (Co), barium (Ba), sulphate (SO42-), alkalinity and dissolved organic carbon in soils, as well as of zinc (Zn), As, Ca, Ba, alkalinity, aluminium (Al) and chromium (Cr) in litter. At 350°C–500°C, divalent cations and organic carbon declined, while soils generated very high Al and Cr concentrations. The time following the fire was important, with the more recent fire generating higher concentrations. The elevated concentrations in 250°C–350°C were attributed to a decomposition of organic matter and mineral transformations, including CaCO3 formation. Based on thermodynamics, we propose a couple of burn severity indicators: activities of calcium and carbonates that are calculated from pH, alkalinity and Ca concentration. The indicators do not only show the degree of post-fire transformations, but they also inform on CaCO3 formation. Further studies include: (1) application to field data, (2) association with organic contaminants, and (3) validation in other geographical locations.Keywords:
Alkalinity
Soil samples were taken from 3 layers of each of the profiles distributed in a pattern of 15m×15m grid over a newly-reclaimed field, and used to determine space variability of total salt, pH and total alkalinity from layer to layer. The results indicate that the total salt content of the research area is generally low, salt accumulation at the surface soil layer is not significant; Soil pH and the total alkalinity is high, generally enough to meet the criteria of soil alkalization; The variation between soil layers in total salt and total alkalinity is moderate, and rather minor in pH; Characteristics of the spatial variation of salt, pH and total alkalinity somewhat differ between the three soil layers, with structural factors playing a leading role. The isoline maps of soil salt content, pH and total alkalinity are obtained with Kriging's interpolation method, and can be used as the basis for amelioration of saline-alkali soils.
Alkalinity
Alkali soil
Soil horizon
Soil test
Cite
Citations (3)
Automated carbon analyzers often are configured to provide estimates of both total organic carbon (TOC) and nonpurgeable organic carbon (NPOC). We show there can be an overestimation of total carbon in the presence of moderate to large quantities of dissolved inorganic carbon. This leads to overestimates of TOC, which is measured as the difference between total carbon and inorganic carbon. Water samples were analyzed as both TOC and NPOC on a Shimadzu TC 5050 Carbon Analyzer. The difference between TOC and NPOC increased as a function of concentrations of dissolved inorganic carbon (DIC). Water samples spiked with DIC ranging from 0 to 100 mg DIC/L also reported increased TOC as large as 8 mg C/L. Our data suggest that the Shimadzu 5050 analyzer (and by analogy other instruments that estimate TOC by difference between TC and IC) overestimates total carbon (TC) when calibrated with an organic standard as recommended by the manufacturer. The magnitude of the overestimation varies both with the amount of DIC present in the sample and the extent to which measurement efficiency of the analyzer is less than 100%. The consequences will be most severe in analysis of samples from systems spanning a large range in DIC. Time series from individual systems are less likely to be affected because the necessary large change in DIC would be detected as changes in pH or other attributes well before any change in DOC. Systems with high DIC will, however, be susceptible to even small variations in measurement efficiency.
Total inorganic carbon
Carbon fibers
Cite
Citations (32)
To effectively monitor and verify carbon dioxide removal through enhanced weathering (EW), this study investigates the use of soil electrical conductivity (EC) and volumetric water content (θ) as proxies for alkalinity and dissolved inorganic carbon (DIC) in soil water. EC-θ sensors offer a cost-effective and straightforward alternative to traditional soil and water sampling methods. In a lab experiment, three different substrates were treated with NaHCO 3 solutions to increase the alkalinity of the soil water and analyze the response. The combination of EC and θ to track the increase in carbonate alkalinity due to EW, and therefore CO 2 consumption, is applicable for low cation exchange capacity (CEC) soil-substrates like the used quartz sand. However, the presence of organic material and pH-dependent CEC complicates the detection of clear weathering signals in soils. In organic-rich and clay-rich soils, only a high alkalinity addition has created a clear EC signal that could be distinguished from a non-alkaline baseline with purified water. Cation exchange experiments revealed that the used soil buffered alkalinity input and thereby might consume freshly generated alkalinity, initially mitigating CO 2 uptake effects from EW application. Effective CEC changes with pH and pH buffering capacity by other pathways need to be considered when quantifying the CO 2 sequestration potential by EW in soils. This should be estimated before the application of EW and should be part of the monitoring reporting and verification (MRV) strategy. Once the soil-effective CEC is raised, the weathering process might work differently in the long term.
Alkalinity
Cation-exchange capacity
Alkali soil
Soil carbon
Soil test
Cite
Citations (5)
Alkalinity
Deposition
Base (topology)
Cite
Citations (0)