Marcelo F. Ortega

Bioaccessibility of metals and human health risk assessment in community urban gardens.

Pseudo-total (i.e. aqua regia extractable) and gastric-bioaccessible (i.e. glycine+HCl extractable) concentrations of Ca, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn were determined in a total of 48 samples collected from six community urban gardens of different characteristics in the city of Madrid (Spain). Calcium carbonate appears to be the soil property that determines the bioaccessibility of a majority of those elements, and the lack of influence of organic matter, pH and texture can be explained by their low levels in the samples (organic matter) or their narrow range of variation (pH and texture). A conservative risk assessment with bioaccessible concentrations in two scenarios, i.e. adult urban farmers and children playing in urban gardens, revealed acceptable levels of risk, but with large differences between urban gardens depending on their history of land use and their proximity to busy areas in the city center. Only in a worst-case scenario in which children who use urban gardens as recreational areas also eat the produce grown in them would the risk exceed the limits of acceptability.

Probabilistic meta-analysis of risk from the exposure to Hg in artisanal gold mining communities in Colombia

Colombia is one of the largest per capita mercury polluters in the world as a consequence of its artisanal gold mining activities. The severity of this problem in terms of potential health effects was evaluated by means of a probabilistic risk assessment carried out in the twelve departments (or provinces) in Colombia with the largest gold production. The two exposure pathways included in the risk assessment were inhalation of elemental Hg vapors and ingestion of fish contaminated with methyl mercury. Exposure parameters for the adult population (especially rates of fish consumption) were obtained from nation-wide surveys and concentrations of Hg in air and of methyl-mercury in fish were gathered from previous scientific studies. Fish consumption varied between departments and ranged from 0 to 0.3 kg d(-1). Average concentrations of total mercury in fish (70 data) ranged from 0.026 to 3.3 μg g(-1). A total of 550 individual measurements of Hg in workshop air (ranging from <DL to 1 mg m(-3)) and 261 measurements of Hg in outdoor air (ranging from <DL to 0.652 mg m(-3)) were used to generate the probability distributions used as concentration terms in the calculation of risk. All but two of the distributions of Hazard Quotients (HQ) associated with ingestion of Hg-contaminated fish for the twelve regions evaluated presented median values higher than the threshold value of 1 and the 95th percentiles ranged from 4 to 90. In the case of exposure to Hg vapors, minimum values of HQ for the general population exceeded 1 in all the towns included in this study, and the HQs for miner-smelters burning the amalgam is two orders of magnitude higher, reaching values of 200 for the 95th percentile. Even acknowledging the conservative assumptions included in the risk assessment and the uncertainties associated with it, its results clearly reveal the exorbitant levels of risk endured not only by miner-smelters but also by the general population of artisanal gold mining communities in Colombia.

Polycyclic Aromatic Hydrocarbons (PAHs) produced in the combustion of fatty acid alkyl esters from different feedstocks: Quantification, statistical analysis and mechanisms of formation

Polycyclic Aromatic Hydrocarbons (PAHs) are pollutants of concern due to their carcinogenic and mutagenic activity. Their emissions are mainly related with the combustion or pyrolysis of the organic matter, such as in fossil fuels combustion. It is important to characterize PAHs in the combustions of biofuels due to their increasing importance in the actual energetic setting. There is a lot of research focused in PAHs emission due to the combustion in diesel engines; but only few of them have analyzed the effect of raw material and type of alcohol used in the transesterification process. Different raw materials (i.e. animal fat, palm, rapeseed, linseed, peanut, coconut, and soybean oils) have been used for obtaining FAME and FAEE. A method for measuring PAHs generated during combustion in a bomb calorimeter has been developed. Combustion was made at different oxygen pressures and the samples were taken from the bomb after each combustion. Samples were extracted and the PAHs amounts formed during combustion were analyzed by GC-MS. This research shows the statistical relationships among the 16 PAHs of concern, biodiesel composition and oxygen pressure during combustion.

Geographical variability of the composition and properties of fatty acid methyl esters from Citrullus colocynthis in Tunisia

ABSTRACT Biofuels are a promising alternative to substitute petroleum-based transportation fuels and could contribute to sustainable development. This work studies the composition and properties of the fatty acid methyl esters (FAMEs) obtained from Citrullus colocynthis, a plant that grows in arid and dry conditions. Samples from seven locations in Tunisia were collected to study the possible variability in their composition and properties to assess the performance in a combustion engine. Results show suitable properties and future studies are encouraged to assess the potential productivity at a large scale, regarding that domestication of the plant could contribute to improving its quality and productivity.

Monitoring of Soil Gases in the Characterization Stage of CO 2 Storage in Saline Aquifers and Possible Effects of CO 2 Leakages in the Groundwater System

The main objective of this chapter is to describe which analytical methodologies and procedures can be applied at the surface to monitor and verify the feasibility of geologically stored carbon dioxide.

Leaching of polycyclic aromatic hydrocarbons (PAHs) from coal dumps reclaimed with apple trees: a mechanistic insight

Polycyclic aromatic hydrocarbons (PAHs) have been identified as compounds that can be incorporated to run-off waters or to aquifers becoming a real threat not only to aquatic organisms but also to humans due to its carcinogenic and mutagenic activity. This work studies the presence of PAHs in a coal dump pile located in the north of Spain (Asturias), downhill a spoil pile of a cinabrium mine. This unique site gives the opportunity to assess whether acid waters have more potential to leach PAHs than normal rainwater (acidified when it gets in contact with coal spoil). The distribution of PAHs and methyl PAHs has shown that their abundance is higher in the path of acid waters which could be caused by the ability of acid water to break bonds of coal macromolecules. This chemical reaction liberates PAHs of less molecular weight that can be detected by GC–MS. Moreover, less soluble PAHs are concentrated on the acid water circulation area and more soluble PAHs more leached by acid water that rainwater, which indicates that PAHs dissolve more in acid waters than in normal rainwater. In addition, this coal spoil pile has been reclaimed with apple trees to make cider for human consumption. Up to 152 different compounds were identified in the tree samples, but neither PAHs nor methyl PAHs were found, pointing to a possible retention of the PAHs in the roots zone. Apple trees in the acid waters path show more concentration in waxes and flavour compounds, indicating a more mature apple.Graphical Abstract