Aerial monitoring of atmospheric particulate matter produced by open-pit mining using low-cost airborne sensors.

Mining is an economic activity that entails the production and displacement of significant amounts of atmospheric particulate matter (PM) during operations involving intense earthcrushing or earthmoving. As high concentrations of PM may have adverse effects on human health, it is necessary to monitor and control the fugitive emissions of this pollutant. This paper presents an innovative methodology for the online monitoring of PM10 concentrations in air using a low-cost sensor (LCS, <300 USD) onboard an unmanned aerial vehicle. After comprehensive calibration, the LCS was horizontally flown over seven different areas of the large Riotinto copper mine (Huelva, Spain) at different heights to study the PM10 distribution at different longitudes and altitudes. The flights covered areas of zero activity, intense mining, drilling, ore loading, waste discharge, open stockpiling, and mineral processing. In the zero-activity area, the resuspension of PM10 was very low, with a weak wind speed (3.6 m/s). In the intense-mining area, unhealthy concentrations of PM10 (>51 µgPM10/m3) could be released, and the PM10 can reach surrounding populations through long-distance transport driven by several processes being performed simultaneously. Strong dilution was also observed at high altitudes (> 50 m). Mean concentrations were found to be 22-89 µgPM10/m3, with peaks ranging from 86 to 284 µgPM10/m3. This study demonstrates the potential applicability of airborne LCSs in the high-resolution online monitoring of PM in mining, thus supporting environmental managers during decision-making against fugitive emissions in a cost-effective manner.

Impact of Potentially Toxic Compounds in Cow Milk: How Industrial Activities Affect Animal Primary Productions.

Potentially toxic elements (PTEs) and polycyclic aromatic hydrocarbons (PAHs) frequently coexist in soils near industrial areas and sometimes in environmental compartments directly linked to feed (forage) and food (milk) production. However, the distribution of these pollutants along the dairy farm production chain is unclear. Here, we analyzed soil, forage, and milk samples from 16 livestock farms in Spain: several PTEs and PAHs were quantified. Farms were compared in terms of whether they were close to (<5 km) or far away from (>5 km) industrial areas. The results showed that PTEs and PAHs were enriched in the soils and forages from farms close to industrial areas, but not in the milk. In the soil, the maximum concentrations of PTEs reached 141, 46.1, 3.67, 6.11, and 138 mg kg-1 for chromium, arsenic, cadmium, mercury, and lead, respectively, while fluoranthene (172.8 µg kg-1) and benzo(b)fluoranthene (177.4 µg kg-1) were the most abundant PAHs. Principal component analysis of the soil PTEs suggested common pollution sources for iron, arsenic, and lead. In the forage, the maximum contents of chromium, arsenic, cadmium, mercury, and lead were 32.8, 7.87, 1.31, 0.47, and 7.85 mg kg-1, respectively. The PAH found in the highest concentration in the feed forage was pyrene (120 µg kg-1). In the milk, the maximum PTE levels were much lower than in the soil or the feed forages: 74.1, 16.1, 0.12, 0.28, and 2.7 µg kg-1 for chromium, arsenic, cadmium, mercury, and lead, respectively. Neither of the two milk samples exceeded the 20 µg kg-1 limit for lead set in EU 1881/2006. Pyrene was the most abundant PAH found in the milk (39.4 µg kg-1), while high molecular weight PAHs were not detected. For PTEs, the results showed that soil-forage transfer factors were higher than forage-milk ratios. Our results suggest that soils and forages around farms near industries, as well as the milk produced from those farms, have generally low levels of PTE and PAH contaminants.

Phytoremediation potential depends on the degree of soil pollution: a case study in an urban brownfield.

Phytoremediation is a cost-effective nature-based solution for brownfield reclamation. The choice of phytoextraction or phytostabilization strategies is highly relevant when planning full-scale treatments. A suitable approach to identify such species involves the evaluation of plants that grow spontaneously on the contaminated sites. Here, we sought to determine the phytoremediation potential of three spontaneous plant species, namely the trees Acer pseudoplatanus L (A. pseudoplatanus) and Betula celtiberica Rothm. & Vasc (B. celtiberica), and the shrub Buddleja davidii Franch (B. davidii), for the recovery of an urban brownfield. To determine the response of the species to the degree of contamination, we conducted soil and vegetation sampling inside and outside the site. The concentrations of As, Cu, and Zn in soil and plant samples were measured, and then various indexes related to phytoremediation were calculated. The translocation factor and transfer coefficient indicated that vegetation outside the brownfield had phytoextraction capacity while the same plants inside the brownfield revealed phytostabilization properties. Given our results, we propose that the selected species are suitable for phytostabilization strategies in areas with high concentrations of contaminants, whereas they could be used for phytoextraction only in soils with low or moderate levels of pollution.

Classical Biomarker and Quantitative Extended Diamondoid Analysis Fingerprints for Crude Oils from Deepwater Developments in Block 17, Lower Congo Basin, Angola.

The organic geochemistry of six oil samples from the offshore Block 17 (Lower Congo Basin, northwestern Angola) was studied by a combination of classical biomarker and extended diamondoid analyses to elucidate source rock facies, the extent of biodegradation, and thermal maturity. Based on molecular data, oils are interpreted as depicting a mixture of two pulses of hydrocarbon generation probably from the Bucomazi and Malembo formations. Geochemical results also gave evidence of mixing of a lacustrine siliciclastic-sourced oil charge and a second more terrestrially derived oil type in the samples analyzed. A single genetic oil family was identified through hierarchical cluster analysis; however, two groups of oils were identified on the basis of their biodegradation levels using the Peters/Moldowan scale. Lower and upper Malembo oils have a slight depletion and a notable absence of n-alkanes, suggesting PM levels of 1 and 2, respectively. Most molecular maturity parameters of the oil samples suggest a maturity level equivalent to the onset of the peak of the oil generative window.

Arsenic release from pyrite ash waste over an active hydrogeological system and its effects on water quality.

Arsenic is a potentially toxic element of concern for environmental compartments, and it is a frequent pollutant in many abandoned industrial sites. In this study, geochemical and hydrogeological tools were used to determine the long-term effects of As-rich pyrite ash disposal (83,000 m3 as estimated by geostatistical tools) in a brownfield located over a quaternary alluvial aquifer. Throughout the site, soil pollution and water table oscillation led to leachates in the form of both run-off and infiltration waters, thereby reducing (ground)water quality (e.g. pH, electrical conductivity) and, in particular, increasing the concentration of arsenic (average approx. 4000 µg/l for one hydrological year). By means of laboratory and in situ measurements, the main mechanisms through which the sulphide remaining in the pyrite ash leaches were identified. In addition, to evaluate the effects of the polluted groundwater on the nearby main river, a mathematical approach using the Domenico analytical groundwater transport model revealed potential concentrations of 49 µg/l of arsenic in the junction between the study aquifer and the river, equivalent to an annual quantity of 49 kg of this element.

Contribution of fluorite mining waste to mercury contamination in coastal systems.

Samples from 13 beaches along the northern Spanish coast, a region with a history of heavy industries, were first screened to identify signs of pollution. High concentrations of Hg and Ba on Vega beach were found, both elements belong to the fluorite ore paragenesis, mined in the surroundings. Samples of beach and fluvial sediments, and nearby soils were collected in Vega beach area to address potential Hg pollution, fate and sources. Most samples showed a similar pollutants fingerprint to that of beach samples, especially those taken from white dunes, registering notable Hg concentrations. Hg was enriched in the finer fractions, and overall the main input was attributed to the mining waste discharged along the coast in the past. Although a specific risk assessment and study of the submerged sediments are advisable for this area, Hg bioavailability and methylation were low, thus indicating that this metal poses a reduced environmental risk.