Polycyclic Aromatic Hydrocarbons in Soil Organic Horizons Depending on the Soil Burn Severity and Type of Ecosystem

Land Degradation & Development

DOI: 10.1002/ldr.2806

Because forest fires are a source of polycyclic aromatic hydrocarbons (PAHs), the influence of burnt conditions is of paramount importance and has not been thoroughly studied yet. In this study, two types of forest stands (Pinus nigra and Pinus pinaster) and two shrubland systems (Erica arborea and Ulex europaeus), differing in litter properties (composition and flammability), were considered. Changes in PAH levels were analysed in unburnt and charred litter, and they were related to different levels of soil burn severity and the organic matter composition of the charred litter, including charcoal and/or ashes. For monitoring PAH levels, an analytical method to determine them in unburnt and burnt woodland samples by pressure liquid extraction using a solid phase extraction cleanup was optimized. The highest levels of PAHs were found in the charred litter of P. pinaster (especially at soil burn severity = 200–400 °C), followed by U. europaeus, which presented similar concentration than Erica arborea and, finally, P. nigra. An association between the low molecular weight PAHs and 50% burn‐off temperature differential scanning calorimetry supports the idea of fire smoke as the main source of low molecular weight PAHs in charred biomass generated at temperatures of 200–400 °C. Instead, the fraction of high molecular weight PAHs is related to hydrogen‐to‐carbon and oxygen‐to‐carbon ash‐free dry weight, with charring depending on their organic matter content in the burnt material. PAH mobility will depend on the solubility of the organic matter, which is higher at higher pHs. The higher risk is the transport downstream to rivers or wet systems.

Copper, Chromium, Nickel, Lead and Zinc levels and pollution degree in firing rage soils

Land Degrad. Develop. 27: 1721–1730 (2016)

DOI: 10.1002/ldr.2497

Small-arms firing ranges are an important source of metal contaminants in the ecosystems located near these facilities, owing to the constant fall and alteration of the ammunition remnants on the soil, particularly in nearby berms. The objectives of this study were to analyse the pollution of chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) in rifle/pistol shooting range soils, to estimate their availability and to evaluate the influence of the ammunition used. The concentrations of Pb, Zn, Cu, Cr and Ni range from 55 to 6·309, 34 to 264, 19 to 98, 40 to 79 and 11 to 33 mg kg 1, respectively. The moderate acidity and organic matter content favour the availability of Pb, followed by Cu > Zn > Ni > Cr. The values of different contamination indexes (Igeo, pollution index and integrated pollution index) suggest that Pb soil contamination is moderate to heavy, especially in the berm area and moderate for Cu and Zn. Lead ammunition is the main source of pollution, but another one was identified owing to the concentrations of Fe, Cr and Ni detected. Further studies are needed to verify their long-term potential adverse effects.

Sepia ink as a surrogate for colloid transport tests in porous media

Journal of Contaminant Hydrology, 191, 2016, 88–98

http://dx.doi.org/10.1016/j.jconhyd.2016.05.005

We examined the suitability of the ink of Sepia officinalis as a surrogate for transport studies of microorganisms and microparticles in porous media. Sepia ink is an organic pigment consisted on a suspension of eumelanin, and that has several advantages for its use as a promising material for introducing the frugal-innovation in the fields of public health and environmental research: very low cost, non-toxic, spherical shape, moderate polydispersivity, size near large viruses, non-anomalous electrokinetic behavior, low retention in the soil, and high stability.

Electrokinetic determinations and transport experiments in quartz sand columns and soil columns were done with purified suspensions of sepia ink. Influence of ionic strength on the electrophoretic mobility of ink particles showed the typical behavior of polystyrene latex spheres. Breakthrough curve (BTC) and retention profile (RP) in quartz sand columns showed a depth dependent and blocking adsorption model with an increase in adsorption rates with the ionic strength. Partially saturated transport through undisturbed soil showed less retention than in quartz sand, and matrix exclusion was also observed. Quantification of ink in leachate fractions by light absorbance is direct, but quantification in the soil profile with moderate to high organic matter content was rather cumbersome.

We concluded that sepia ink is a suitable cheap surrogate for exploring transport of pathogenic viruses, bacteria and particulate contaminants in groundwater, and could be used for developing frugal-innovation related with the assessment of soil and aquifer filtration function, and monitoring of water filtration systems in low-income regions.

Nickel, Lead and Zinc Sorption in a Reclaimed Settling Pond Soil

Pedosphere

Volume 26, Issue 1, February 2016, Pages 39-48

doi:10.1016/S1002-0160(15)60020-0

The wastes used to amend soils sometimes have high concentrations of metals such as nickel (Ni), lead (Pb) and zinc (Zn). To determine the capacity of soils to retain these metals, the sorption capacities of different mine soils with and without reclamation treatments (tree vegetation and waste amendment) for Ni, Pb and Zn in individual and competitive situations were evaluated using the batch sorption technique. The untreated settling pond soil had low capacity for Ni, Pb and Zn retention. The site amended with wastes (sewage sludges and paper mill residues) increased the sorption capacity most, probably because of the higher concentrations of soil components with high retention capacity such as carbon and clay fraction. No significant competition was observed between metals in the competitive sorption experiment, indicating that the maximum of sorption was not achieved by adding 0.5 mmol L−1 of metal. We can conclude that, despite the possible additions of Ni, Pb and Zn from wastes to degraded soils, sewage sludges and paper mill residues have a high sorption capacity that would prevent the metals from being in a mobile form.

As(V) and P Competitive Sorption on Soils, By-Products and Waste Materials

Int. J. Environ. Res. Public Health 2015, 12(12), 15706-15715

doi:10.3390/ijerph121215016

Batch-type experiments were used to study competitive As(V) and P sorption on various soils and sorbent materials. The materials assayed were a forest soil, a vineyard soil, pyritic material, granitic material, coarsely and finely ground mussel shell, calcinated mussel shell ash, pine sawdust and slate processing fines. Competition between As(V) and P was pronounced in the case of both soils, granitic material, slate fines, both shells and pine sawdust, showing more affinity for P. Contrary, the pyritic material and mussel shell ash showed high and similar affinity for As(V) and P. These results could be useful to make a correct use of the soils and materials assayed when focusing on As and P removal in solid or liquid media, in circumstances where both pollutants may compete for sorption sites.