Pb pollution in soils from a trap shooting range and the phytoremediation ability of Agrostis capillaris

Environmental Science and Pollution Research, 2016, 23, 1312–1323.

DOI: 10.1007/s11356-015-5340-7

Pb pollution caused by shooting sport activities is a serious environmental problem that has increased considerably in recent decades. The aims of this study were firstly to analyze Pb pollution in soils from a trap shooting range abandoned in 1999, secondly to study the effectiveness of different extractants [CaCl2, DTPA, NH4OAc, low molecular weight organic acids (LMWOA), and bidistilled water (BDW)] in order to determine Pb bioavailability in these soils, and finally to evaluate the phytoremediation ability of spontaneous vegetation (Agrostis capillaris L.). To this end, 13 soils from an old trap shooting range (Galicia, NW Spain) were studied. It was found that Pb levels in the soils were higher than 100 mg kg−1, exceeding the generic reference levels, and three of these samples even exceeded the USEPA threshold level (400 mg kg−1). In general, the reagent that best represents Pb bioavailability and has the greatest extraction efficiency was CaCl2, followed by DTPA, NH4OAc, LMWOA, and BDW. A. capillaris Pb contents ranged between 9.82 and 1107.42 mg kg−1 (root) and between 6.43 and 135.23 mg kg−1 (shoot). Pb accumulation in roots, as well as the presence of secondary mineral phases of metallic Pb in the adjacent soil, showed the phytostabilization properties of A. capillaris.

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.

TOF-SIMS and FE-SEM/EDS to verify the heavy metal fractionation in serpentinite quarry soils

CATENA, 136, 2016, 30–43

http://dx.doi.org/10.1016/j.catena.2015.03.005

This study aims at extensively defining serpentinite quarry soils and analysing their content and distribution of heavy metals using chemical sequential extraction. The association with the different geochemical phases of the soil was verified using TOF-SIMS and SEM-EDS techniques. Seven soils were chosen in two serpentinite quarries located in Moeche (M) and Silleda (C) (Galicia, northwest of Spain). The selected areas for soil sampling were: dump sites (M1, M2 and C1), rock extraction sites (M3, C2), and quarry boundaries (M4 and C3). The total soil concentration of Co, Cr, Ni, and V varied from 1472 to 7132, 1499 to 4309, 76 to 373, and 21 to 140 mg kg− 1, respectively. In all cases they exceed the maximum limit permitted in soils. After chemical sequential extraction it was found that the high content of Co, Cr, Ni, and V is associated with the residual fraction of the soils. In addition, Fe and Mn oxides have a high capacity for Co fixation, whereas Cr, Ni, and V are mainly associated with magnesium silicates. The fractions related to organic matter and the soluble or available forms are, respectively low and very low, not exceeding 2.5% in any of the soils. This association of the metals with magnesium silicates and Fe oxides, and the low content of metals bound to organic matter were identified by using the TOF-SIMS and SEM-EDS techniques. Both techniques confirmed and verified the results obtained during the chemical sequential extraction by checking the interaction of heavy metals with the different components of the soil.

Using calcium phosphate nanoparticles to reduce metal mobility in shooting range soils

Science of The Total Environment, 571, 2016, 1136–1146

http://dx.doi.org/10.1016/j.scitotenv.2016.07.108

Shooting activities are a very important source of contamination as they are commonly detected high concentrations of Pb in the soils from these facilities. Different remediation methods imply the immobilization of the pollutants by decreasing their mobility and availability and nanotechnology is a promising technique in this field. The effectiveness of calcium phosphate nanoparticles (CPNs) in the remediation of small-arms firing range and trap shooting range soils is evaluated in this work. The operationally defined extractable content of Pb, Cu and Zn is determined together with the interaction of the pollutants with the nanomaterials. Soil samples were treated with the CPNs and after the treatment the extractable contents of Cu, Pb and Zn decrease. To check the retention by the nanoparticles TOF-SIMS (Time of Flight Secondary Ion Mass Spectrometry) and HR-TEM-EDS (High Resolution Transmission Electron Microscopy with Energy Dispersive X-ray Spectroscopy) techniques were applied. The association of Pb and Cu to the CPNs was demonstrated by TOF-SIMS although it also indicated that not all the Pb and Cu contents are linked to the nanoparticles. By means of HR-TEM/EDS it was made out the filamentous shape and the size (50–150 nm long and 20–40 nm wide) of the CPNs together with their elemental composition (Ca, P and O). The CPNs were identified in treated soil samples together with signals of metals. The decrease on metal extractability detected is, in part, due to the association with CPNs but still more investigation is needed regarding mobility and availability of potentially hazardous elements in soils treated with nanoparticles.

Lithological and land-use based assessment of heavy metal pollution in soils surrounding a cement plant in SW Europe

Science of The Total Environment 562, 2016, 179–190

http://dx.doi.org/10.1016/j.scitotenv.2016.03.198

We study the influence of phasing out a cement plant on the heavy metal (Hg, Pb and Cr) content in the surrounding soils, taking into account factors often neglected, such as contributions due to local lithology or land use. The range of total Hg was 10–144 µg kg− 1, reaching up to 41 and 145 mg kg− 1 for total contents of Pb and Cr, respectively. Forest soils showed higher concentration of Hg than prairie soils, indicating the importance of land use on the accumulation of volatile heavy metals in soils. In forest soils, total Hg showed a trend to decrease with soil depth, whereas in prairie soils the vertical pattern of heavy metal concentrations was quite homogeneous. In most cases, the distance to the cement plant was not a factor of influence in the soils content of the analyzed heavy metals. Total Pb and Cr contents in soils nearby the cement plant were quite similar to those found in the local lithology, resulting in enrichment factor values (EF's) below 2. This suggests that soil parent material is the main source of these heavy metals in the studied soils, while the contribution of the cement plant to Pb and Cr soil pollution was almost negligible. On the contrary, the soils surrounding the cement plant accumulate a significant amount of Hg, compared to the underlying lithology. This was especially noticeable in forest soils, where Hg EF achieved values up to 36. These results are of relevance, bearing in mind that Hg accumulation in soils may be an issue of environmental concern, particularly in prairie soils, where temporal flooding can favor Hg transformation to highly toxic methyl-Hg. In addition, the concurrence of acid soils and total-Cr concentrations in the range of those considered phytotoxic should be also stressed.