Browsing by Author "Alvarenga, Paula"
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- Assessment of trace element pollution and its environmental risk to freshwater sediments influenced by anthropogenic contributions: The case study of Alqueva reservoir (Guadiana Basin)Publication . Palma, Patricia; Ledo, Lidia; Alvarenga, PaulaThe Guadiana Basin.(SW Iberian Peninsula) is affected by acid mine drainage (AMD), a consequence of ancient mining activities in the Iberian Pyrite Belt (IPB). Consequently, the sedimerits at the Alqueva reservoir (SE Portugal) in the Guadiana Basin are potentially contaminated by trace elements, which make important: (i) to characterize the status of trace element pollution of the sediments; (ii) to evaluate the mobility and the bioavailability of As, Cd, Cu, Cr, Pb and Zn; and (iii) to assess the environmental risk associated with the total and bioavailable concentrations of trace elements, using the sediment quality guidelines (SQGs) and the risk assessment code (RAC). Metal enrichment factors (EF) and geoaccumulation indexes (I-geo), determined taking into account the regional background levels, revealed that, among the metals analyzed, Cd contributed the highest to pollution levels followed by Pb and As. Despite the trace element contamination of the Alqueva sediments, the sequential extraction showed that Most of them are found in the oxidizable and residual fractions, which indicates that they are sparingly bioavailable, with exception of Cd (acid-labile fraction) and Pb (reducible fraction). Based on the RAC, Cd was the only metal that presented a high risk, while Pb, As and Zn showed a medium risk. Moreover, the SQGs revealed the existence of certain areas of extremely high risk, particularly related to high concentrations of total As and, in less extent, of Pb and Cd, associated with AMD, wastewater discharges and runoff of plant protection products from agricultural fields located near the reservoir. (C) 2015 Elsevier By. All rights reserved.
- Beneficial use of dewatered and composted sewage sludge as soil amendments: behaviour of metals in soils and their uptake by plantsPublication . Alvarenga, Paula; Farto, Márcia; Mourinha, Clarisse; Palma, PatríciaIn Portugal, where soils have a very low topsoil organic matter content, the use of sewage sludge (SS) as organic soil improvers seems an attractive option, because it would enable organic matter, N, P, K and other nutrients to be recycled. However, the risk of this practice must be properly assessed. The aim of this study was to evaluate the potential risk of the use of dewatered and composted SS as soil amendments. For this purpose, SS from two different wastewater treatment plants (SS1 and SS2), and a compost produced from SS and agricultural wastes (AWSSC), were characterized for their total metal concentrations, organic contaminants and indicator pathogens, and used in a pot experiment with three application rates, 6, 12 and 24 ton dry matter/ha, cultivated with a hybrid variety of sorghum and Sudan grass (Sorghum bicolor x Sorghum sudanense var. Rocket). SS1 and AWSSC met the legal requirements to be applied to soils, but SS2 had a high content of pathogens, which compromised its use. Both dewatered SS had a marked beneficial effect on plant production and on soil nutritional characteristics, more pronounced than in the case of AWSSC application, without a significant increase in total and in mobile metals concentration in soils. Bioaccumulation factors for metals in plants were low, and their concentrations in the aboveground plant material were lower than the maximum tolerable level for cattle, used as a risk indicator of metal entry into the human food chain. However, it will be necessary, in future studies, to evaluate the potential risk of the observed increase in the mobilisable content of Cu and Zn in soil, as a consequence of the application of these organic materials.
- Ecotoxicological assessment of the potential impact on soil porewater, surface and groundwater from the use of organic wastes as soil amendmentsPublication . Alvarenga, Paula; Mourinha, Clarisse; Farto, Marcia; Palma, Patrícia; Sengo, Joana; Morais, Marie-Christine; Cunha-Queda, CristinaThis study aimed to assess the potential impact on soil porewater, surface and groundwater from the beneficial application of organic wastes to soil, using their eluates and acute bioassays with aquatic organisms and plants: luminescence inhibition of Vibrio fischeri (15 and 30 min), Daphnia magna immobilization (48 h), Thamnocephalus platyurus survival (24 h), and seed germination of Lolium perenne (7 d) and Lactuca sativa (5 d). Some organic wastes' eluates promoted high toxic responses, but that toxicity could not be predicted by their chemical characterization, which is compulsory by regulatory documents. In fact, when organisms were exposed to the water-extractable chemical compounds of the organic wastes, the toxic responses were mare connected to the degree of stabilization of the organic wastes, or to the treatment used to achieve that stabilization, than to their contaminant load. That is why the environmental risk assessment of the use of organic wastes as soil amendments should integrate bioassays with eluates, in order to correctly evaluate the effects of the most bioavailable fraction of all the chemical compounds, which can be difficult to predict from the characterization required in regulatory documents. According to our results, some rapid and standardized acute bioassays can be suggested to integrate a Tier 1 ecotoxicological evaluation of organic wastes with potential to be land applied, namely luminescence inhibition of V fischeri, D. magna immobilization, and the germination of L. perenne and L sativa.
- Field study on the accumulation of trace elements by vegetables produced in the vicinity of abandoned pyrite minesPublication . Alvarenga, Paula; Simoes, Isabel; Palma, Patrícia; Amaral, Olga; Matos, Joao XavierTo evaluate the accumulation of trace elements (TE) by vegetables produced in the vicinity of abandoned pyrite mines, eighteen different small farms were selected near three mines from the Portuguese sector of the Iberian Pyrite Belt (Sao Domingos, Aljustrel and Lousal). Total and bioavailable As, Cu, Pb, and Zn concentrations were analyzed in the soils, and the same TE were analyzed in three different vegetables, lettuce (Lactuca sativa), coriander (Coriandrum sativum), and cabbage (Brassica oleracea), collected at the same locations. The soils were contaminated with As, Cu, Pb, and Zn, since their total concentrations exceeded the considered soil quality guideline values for plant production in the majority of the sampling sites. The maximum total concentrations for those TE were extremely high in some of the sampling sites (e.g. 1851 mg As kg(-1) in Sao Domingos, 1126 mg Cu kg(-1) in Aljustrel, 4946 mg Pb kg(-1) in Sao Domingos, and 1224 mg Zn kg(-1) in Aljustrel). However, the soils were mainly circumneutral, a factor that contributes to their low bioavailable fractions. As a result, generally, the plants contained levels of these elements characteristic of uncontaminated plants, and accumulation factors for all elements <1, typical of excluder plants. Furthermore, the estimated daily intake (EDI) for Cu and Zn, through the consumption of these vegetables, falls below the recommended upper limit for daily intake of these elements. The sampling site that stood out from the others was located at Sao Joao de Negrilhos (Aljustrel), where bioavailable Zn levels were higher, a consequence of the slight acidity of the soil. Therefore, the Zn content in vegetables was also higher, characteristic of contaminated plants, emphasizing the risk of Zn entering the human food chain via the consumption of crops produced on those soils. (C) 2013 Elsevier B.V. All rights reserved.
- Organic wastes as soil amendments - Effects assessment towards soil invertebratesPublication . Renaud, Mathieu; Chelinho, Sonia; Alvarenga, Paula; Mourinha, Clarisse; Palma, Patrícia; Sousa, Jose Paulo; Natal-da-Luz, TiagoUsing organic wastes, as soil amendments, is an important alternative to landfilling with benefits to soil structure, water retention, soil nutrient and organic matter concentrations. However, this practice should be monitored for its environmental risk due to the frequent presence, of noxious substances to soil organisms. To evaluate the potential of eight organic wastes with different origins, as soil amendments, reproduction tests with four soil invertebrate species (Folsomia candida, Enchytraeus crypticus, Hypoaspis aculeifer, Eisenia feticta) were performed using gradients of soil waste Mixtures. Results obtained demonstrated that contaminant concentrations required by current legislation might not be a protective measure for the soil ecosystem, as they do not properly translate the potential toxicity of wastes to soil invertebrates. Some wastes with contaminant loadings below thresholds showed higher toxicity than wastes with contaminants concentrations above legal limits. Also, test organism reproduction was differently sensitive to the selected wastes, which highlights the need to account for different organism sensitivities and routes of exposure when evaluating the toxicity of such complex mixtures. Finally this study shows that when combining chemical and ecotoxicological data, it is possible to postulate on potential sources of toxicity, contributing to better waste management practices and safer soil organic amendment products. (C) 2017 Elsevier B.V. All rights reserved.
- Quality assessment of a battery of organic wastes and composts using maturity, stability and enzymatic parametersPublication . Alvarenga, Paula; Mourinha, Clarisse; Farto, Marcia; Palma, Patrícia; Sengo, Joana; Morais, Marie-Christine; Cunha-Queda, CristinaChemical and biological parameters (NH4+-N/NO3--N ratio, humification indices, and the activities of hydrolytic exoenzymes), commonly used to assess compost maturity and/or stability, were considered for the quality evaluation of a battery of organic materials, intended to be land applied. Acid and alkaline phosphatases, beta-glucosidase, proteases and beta-glucosaminidase activities proved to be reliable tests to distinguish the organic materials that were in an active stage of microbial activity, highly correlated to the chemical parameters NH4+-N content and NH4+-N/NO3--N ratio. In fact, these chemical parameters evidenced as important in the quality assessment of an organic material, strongly correlated with the biological parameters. The same was not true for the majority of the humification indices, which proved inadequate to compare the quality of such diverse organic materials. This was demonstrated by a multivariate statistical treatment of data, performed with these results in combination with results from the Dewar self-heating test, respiration activity and germination index, obtained in previous studies. Concluding, in a similar scenario, where the organic materials in evaluation are varied, both in the raw material an in the stability of the organic matter, the quality should be assessed by the integrated use of both chemical and biological parameters.