Amaya Franco-Uría

Source identification of heavy metals in pastureland by multivariate analysis in NW Spain.

Arable layer of pastureland in Galicia (NW Spain) was monitored for total content of heavy metals, and analysed by multivariate statistical techniques, in order to investigate the different origin that metals may have in pasture soils. Principal component analysis (PCA), cluster analysis (CA) and correlation matrix (CM) were applied to 65 samples in which the total concentrations of Mn, Fe, Zn, Cu, Cr, Co, Ni, Cd and Pb were measured. Four significant components were extracted by PCA, explaining 78.830% of total variance. Mn, Co and Ni (and partially Cu), and Fe and Cr, were associated in two lithogenic components, respectively, while an anthropogenic origin was identified for Cd, Pb and Zn. Zn (and Cu) were mainly associated with soil fertilisation by cattle slurry or with other activities regarding cattle management. Although the origin of Cd and Pb was also attributed to slurry application, other sources like commercial fertilisers, vehicle exhaust or aerial deposition were not discarded as possible contributors. CA confirmed and completed the results obtained by PCA, classifying the data in four groups representing different areas. Group 1 represented samples corresponding to areas were the application of manure was moderate, while Group 2 included samples of lithogenic origin. Highest contents of anthropogenic metals were included in Group 3, although soils in this cluster were not considered as polluted. The last cluster grouped the samples with the lowest content of all the metals analysed, representing areas correctly managed and not affected by other external sources. Finally, the results obtained by CM agreed with PCA and CA, also helping in elucidating individual relationships between metals.

Inventory of heavy metal content in organic waste applied as fertilizer in agriculture: evaluating the risk of transfer into the food chain

Background, aim, and scopeIn this work, an environmental risk assessment of reusing organic waste of differing origins and raw materials as agricultural fertilizers was carried out. An inventory of the heavy metal content in different organic wastes (i.e., compost, sludge, or manure) from more than 80 studies at different locations worldwide is presented.Materials and methodsThe risk analysis was developed by considering the heavy metal (primarily Cd, Cu, Ni, Pb, and Zn) concentrations in different organic residues to assess their potential environmental accumulation and biotransfer to the food chain and humans. A multi-compartment model was used to estimate the fate and distribution of metals in different environmental compartments, and a multi-pathway model was used to predict human exposure.ResultsThe obtained hazard index for each waste was concerning in many cases, especially in the sludge samples that yielded an average value of 0.64. Among the metals, Zn was the main contributor to total risk in all organic wastes due to its high concentration in the residues and high biotransfer potential. Other more toxic metals, like Cd or Pb, represented a negligible contribution.ConclusionsThese results suggest that the Zn content in organic waste should be reduced or more heavily regulated to guarantee the safe management and reuse of waste residues according to the current policies promoted by the European Union.

Risk assessment of persistent pharmaceuticals in biosolids: Dealing with uncertainty

A screening-level risk assessment of biosolids-borne PPCPs in agricultural scenarios was developed in this work. While several of these compounds are efficiently removed in sewage treatment plants (STPs), others are recalcitrant to degradation and can be found in sludge at significant levels. As the rate of biosolids reuse for fertilising and/or amendment purposes is increasing, it is necessary to evaluate the fate in soil and possible biotransfer of this type of pollutants in the long-term. The study includes six compounds that were selected considering data availability, presence in sludge and persistence. Due to the scarce data still present in literature, a probabilistic assessment to address uncertainty was developed. A 95th percentile of the hazard index (HI) exceeding 1 was obtained, with main contributions of triclosan and carbamazepine. Although these estimates were obtained under a worst-case approach, and that they can vary depending on scenario characteristics, they change the least-concern classification associated to the presence of PPCPs in biosolids. A sensitivity analysis indicates the high influence of application rate and sludge concentration level on the results. Thus, the importance of developing new strategies of removal in advanced STPs and the establishment of a specific biosolids reuse regulation including this type of compounds acquires an added significance.

Multicorrelation models and uptake factors to estimate extractable metal concentrations from soil and metal in plants in pasturelands fertilized with manure.

Environmental risk assessment (ERA) is a useful methodology to estimate the possible adverse effects to human health due to contaminants exposure. In the case of agricultural scenarios, this method requires knowing the concentrations of contaminants in soil solution and vegetation, among other parameters. This study aimed to develop multicorrelation models to estimate metal extractable from soil as a function of total metal concentration in soil and soil properties in a cattle manure application scenario. It also aimed to estimate metal concentrations in plant by soil-plant uptake factors (UF). All the multicorrelation models obtained were significant, ranging R(2) values from 0.44 for Cd to 0.92 for Cu. Soil-plant UF were an adequate method for the estimation of metal concentration in plant, since the relationship between the soil-plant UF and the extractable metal concentration from soil was significantly described by a power model, for all the heavy metals.

A risk-based decision tool for the management of organic waste in agriculture and farming activities (FARMERS)

Currently, specific management guidelines must be implemented for guaranteeing the safe reuse of organic waste in agriculture. With that aim, this work was focused on the development of a decision support tool for a safe and sustainable management of cattle manure as fertiliser in pastureland, to control and limit metal accumulation in soil and to reduce metal biotransfer from soil to other compartments. The system was developed on the basis of an environmental risk assessment multi-compartmental model. In contrast to other management tools, a long-term dynamic modelling approach was selected considering the persistence of metals in the environment. A detailed description of the underlying flow equations which accounts for distribution, human exposure and risk characterisation of metals in the assessed scenario was presented, as well as model parameterization. The tool was implemented in Visual C++ and is structured on a data base, where all required data is stored, the risk assessment model and a GIS module for the visualization of the scenario characteristics and the results obtained (risk indexes). The decision support system allows choosing among three estimation options, depending on the needs of the user, which provide information to both farmers and policy makers. The first option is useful for evaluating the adequacy of the current management practices of the different farms, and the remaining ones provides information on the measures that can be taken to carry out a fertilising plan without exceeding risk to human health. Among other results, maximum values of application rates of manure, maximum permissible metal content of manure and maximum application times in a particular scenario can be estimated by this system. To illustrate tool application, a real case study with data corresponding to different farms of a milk production cooperative was presented.

Valorisation of fish by-products against waste management treatments--Comparison of environmental impacts.

Reuse and valorisation of fish by-products is a key process for marine resources conservation. Usually, fishmeal and oil processing factories collect the by-products generated by fishing port and industry processing activities, producing an economical benefit to both parts. In the same way, different added-value products can be recovered by the valorisation industries whereas fishing companies save the costs associated with the management of those wastes. However, it is important to estimate the advantages of valorisation processes not only in terms of economic income, but also considering the environmental impacts. This would help to know if the valorisation of a residue provokes higher impact than other waste management options, which means that its advantages are probably not enough for guarantying a sustainable waste reuse. To that purpose, there are several methodologies to evaluate the environmental impacts of processes, including those of waste management, providing different indicators which give information on relevant environmental aspects. In the current study, a comparative environmental assessment between a valorisation process (fishmeal and oil production) and different waste management scenarios (composting, incineration and landfilling) was developed. This comparison is a necessary step for the development and industrial implementation of these processes as the best alternative treatment for fish by-products. The obtained results showed that both valorisation process and waste management treatments presented similar impacts. However, a significant benefit can be achieved through valorisation of fish by-products. Additionally, the implications of the possible presence of pollutants were discussed.

Fish discards management: Pollution levels and best available removal techniques

Fish discards and by-catch issues are highly topical subjects that are permanently under a social focus. Two main approaches are being considered to address this discard problem: reducing the by-catch and increasing by-catch utilization. Interest in increased by-catch valorization may arise from a greater demand for fish products, such as the development of new markets for previously discarded species, the use of low-value specimens for aquaculture or the creation of value-added fish products for the food, pharmaceutical or cosmetic industries. However, contaminants present in fish discards may be transferred to their valorized products, leading to possible long-term bioaccumulation and subsequent adverse health effects. In this valorization framework, the aim is to promote responsible and sustainable management of marine resources. The pollutant levels in catches from European fisheries and the best available decontamination techniques for marine valorized discards/by-products are compiled and analyzed in this work.

Integrative health risk assessment of air pollution in the northwest of Spain

Levels, origins and potential risks due to different air pollutants (ozone, SO2 and particle-borne metals) in NW Spain were investigated in eight locations affected by different emission sources. All monitored locations suffered the influence of traffic and industrial emissions, being this influence more important in urban locations. Although average values of the estimated hazard index (HI) due to particle-borne metals showed values lower than one, maximum values of this parameter exceeded this safety limit in urban locations. In general, Ni and As were identified as those metals most contributing to the HI. Furthermore, the presence of industrial emission episodes produced a significant increase in the magnitude of the HI in two of the seven urban areas. Therefore, the frequency and intensity of these episodes should be further investigated. Finally, levels of airborne and particle-borne pollutants were integrated with the aim of providing a comprehensive assessment of health risk. According to an established indexing system, air quality can be classified from good to moderate, being the southern urban locations (the most densely populated and industrialised ones) presenting the worst values. However, either the high or the low influence of acute and chronic-effect pollutants on air quality depends on the location.

Pollutant levels in discarded fish species by Spanish trawlers operating in the Great Sole Bank and the Atlantic coast of the Iberian Peninsula.

Organic and inorganic pollutant levels were determined for the most discarded species from trawlers operating in Great Sole and Spanish coastal fishing grounds. Results for heavy metals indicated that Cd can reach values higher than legal limits for some species and tissues, while Hg and Pb concentrations are below established values. No significant variation was noticed with fishing grounds, but both season influences in the case of Pb and interspecies variation for Hg and Cd have been detected. Valorization recommendations could be therefore established according to the levels found in the different species.

Fate of pharmaceuticals in soil after application of STPs products: Influence of physicochemical properties and modelling approach

Depurated effluents can be employed as reclaimed water for irrigation in regions with low precipitations, while nutrients-rich biosolids are usually applied as fertilizer for agricultural purposes. However, both practices may result in the accumulation of micropollutants in the soil compartment, the contamination of groundwater, and/or their biotransfer to different living organisms until they finally may reach human receptors. The fate and transport of seven pharmaceutical and personal care products (PPCPs) with different physicochemical properties was analysed for these scenarios employing two different models: the buckets model and the HYDRUS-1D software package. The results indicated that these compounds have a low potential to contaminate groundwater in the type of soil under study (silty loam), although triclosan tended to accumulate in the top layers of the soil. Similar conclusions were reached through both models, although they predicted different solute plant uptake and accumulation patterns of the evaluated compounds. Therefore, the buckets model can be considered as an adequate option to perform a screening level assessment of these compounds. However, HYDRUS-1D could provide more information on the fate of pharmaceuticals in soil, thus contributing to reduce the uncertainty already associated to PPCPs. Additionally, the significant difference of the Hazard Index (HI) obtained from a human health risk assessment performed using the estimated soil concentrations from both models also contributed to recommend the use of a model that considers all the relevant mechanisms of mass transfer to reduce overestimation of risk.