Fitorremediação em solos contaminados com arsénio, por duas espécies de Eucalyptus (Eucalyptus globulus Labill e Eucalyptus nitens Deane & Maiden)

Nos últimos anos, com o aumento da população mundial e a sobre-exploração dos recursos naturais (devido à mineração, agricultura e industria), a poluição dos solos (nomeadamente com arsénio) tem gradualmente aumentado. Neste enquadramento, neste estudo, caracterizou-se a deposição e o teor médio do arsénio nas zonas mineiras de Neves-Corvo e de São Domingos, para definição e implementação de um ensaio experimental de fitorremediação no Campus da Faculdade de Ciências e Tecnologia / Universidade Nova de Lisboa. Após transplantação e aclimatação das plantas da Eucalyptus globulus Labill e E. nitens Deane & Maiden, com 11 e 17 meses de idade, respetivamente, entre Janeiro e Julho de 2015, as plantas foram submetidas a 33 e 66 mg de As Kg-1solo. Procedeu-se então a uma caracterização bimensal da cinética de absorção e translocação do arsénio para a parte aérea, aferindo-se ainda os parâmetros de crescimento e as taxas de síntese de fotoassimilados. Face ao aumento da concentração de arsénio no solo, verificou-se o aumento dos respetivos teores nas raízes (até 102,2 e 133,3 μg As g-1peso seco, na E. globulus e E. nitens, respetivamente) e nas folhas (até 11,64 μg As g-1peso seco na E. nitens). Constatou-se ainda que a E. globulus registou uma maior taxa de crescimento, produção de biomassa e maior tolerância ao arsénio. Paralelamente, na E. nitens o tratamento com 200 mg de As apresentou variações significativas, relativamente à parametrização fotossintética, evidenciando-se danos no fotossistema II. Não existindo nenhuma legislação europeia ou nacional que promova, ou impossibilite, a descontaminação de solos por fitorremediação, por ser de interesse público, discute-se, a implementação da E. globulus, como possível solução para a descontaminação de áreas poluídas com arsénio, nomeadamente na mina de Neves-Corvo

The tolerance of eucalyptus globulus to soil contamination with arsenic

UID/FIS/04559/2020The contamination of abandoned mining areas is a problem worldwide that needs urgent attention. Phytoremediation emerges as a successful method to extract different contaminants from the soil. In this context, Eucalyptus globulus plants growing in soils artificial contaminated with arsenic (As) were used to access its phytoremediation capabilities. The effects of As on photosynthetic performance were monitored through different physiological parameters, whereas the uptake and translocation of As and the putative effects on calcium, iron, potassium, and zinc levels on plants were evaluated by X-ray fluorescence analysis. Root system is the major accumulator organ, while the translocation to the above-ground organs is poor. In the end of the experiment, the root biomass of plants treated with 200 μg As mL−1 is 27% and 49.7% lower than equivalent biomass from plants treated with 100 μg As mL−1 and control plants, respectively. Each plant can accumulate 8.19 and 8.91 mg As after a 6-month period, when submitted to 100 As and 200 As, respectively. It seems to exist an antagonistic effect of As on Zn root uptake by E. globulus. In general, the tested concentrations do not influence negatively plant metabolism, indicating that this species is suitable for plantation in contaminated areas.publishersversionpublishe

Nutritional profile of the Portuguese cabbage (Brassica oleracea L var. costata) and its relationship with the elemental soil analysis

The economic and financial crisis has increased the number of urban horticulture on lands close to present or past industrial areas. "Tronchuda" or the Portuguese cabbage (Brassica oleraceae L var. costata DC) was studied because of its importance in Portuguese diet. It belongs to a number of economically significant horticultural crops (Brassica species), which are also known to be nutritionally well-balanced vegetables. "Tronchuda" produced in urban horticultures from 4 regions of mainland Portugal was studied for its nutritional profile along with elemental soil analysis of each sampling site. This study revealed significant interactions between essential elements in soil and plant leaves - the edible part of the plant for human nutrition. In general, these organs contained poor concentrations of Fe and Si, while Mn is absent, regardless of the sampling sites. Conversely, Ca levels were abundant with values ranging between 3.3% and 3.9%. Soils from CAP showed a soil nutrient exhaustion of Fe, Mn and Mo, although the highest protein and sucrose contents in the leaves was observed in plants growing in those soils. Protein, lipids and carbohydrates concentrations differed according to sampling site, reflecting different production practices.publishersversionpublishe

ACUMULAÇÃO DE METAIS PESADOS E ALTERAÇÃO DAS PROPRIEDADES FÍSICAS E QUÍMICAS DE AREIAS DE DUNAS LITORÂNEAS

Nos dois últimos séculos, na orla costeira de Portugal, generalizou-se a prática agrícola em areias de duna com a aplicação de agroquímicos, sem controlo técnico, de onde resultaram alterações da composição físico-química e acumulação de metais pesados nas areias. Com o objetivo de avaliar os efeitos do manejo agrícola foram coletadas e caracterizadas, do ponto de vista físico e químico, amostras das dunas, entre os 0,0 cm e os 20 cm de profundidade, com e sem prática agrícola. Foi determinada, por ensaio de peneiramento, a fração fina (partículas com diâmetro inferior a 0,074 mm) e pelo método MAB – Peróxido a composição em matéria orgânica. Foi estimada a umidade das amostras e determinado, pelo método eletroquímico, o pH, a condutividade elétrica e o potencial de oxirredução. A composição química foi analisada por fluorescência de raios-x. Verificou-se que o manejo agrícola das dunas resultou no aumento da fração fina, da matéria orgânica, da umidade, da condutividade elétrica e do potencial de oxirredução das areias. O pH diminuiu, de básico para valores próximos de neutro, aumentando o risco de acumulação e mobilização de Fe, Mn, Cu, Zn, Pb, As, Zr, Th, Rb, Cr, V, Ni, Hg, Co e U

Soil Arsenic Toxicity Impact on the Growth and C-Assimilation of <i>Eucalyptus nitens</i>

The selection of adequate plants that can cope with species that can live in contaminated/degraded and abandoned mining areas is of utmost importance, especially for environmental management and policymakers. In this framework, the use of a fast-growing forestry species, such as Eucalyptus nitens, in the recovery of arsenic (As) from artificially contaminated soils during a long-term experiment was studied. Roots can accumulate to levels ranging between 69.8 and 133 μg g−1 for plants treated with 100 and 200 µg As mL−1, respectively, while leaves between 9.48 μg g−1 (200 As) and 15.9 μg g−1 (100 As) without apparent morphological damage and toxicity symptoms. The C-assimilation machinery performance revealed a gradual impact, as evaluated through some gas exchange parameters such as the net photosynthetic rate (Pn), stomatal conductance to H2O (gs), and transpiration rate (E), usually with the greater impacts at the highest As concentration (200 As), although without significantly impacting the PSII performance. The As effects on the uptake and translocation of Ca, Fe, K, and Zn revealed two contrasting interferences. The first one was associated with Zn, where a moderate antagonism was detected, whereas the second one was related to Fe, where a particular enrichment in leaves was noted under both As treatments. Thus, it seems to exist a synergistic action with an impact on the levels of the photosynthetic pigments in As-treated plant leaves, compared with control plants. E. nitens must be considered as an alternative when phytoremediation processes are put into practice in our country, particularly in areas with cool climatic conditions

Accumulation of heavy metals and alterations of the physical and chemical properties of the litoral dunes

During past two centuries, dunes Portuguese coastline is being used for agricultural practices with intensive use of agrochemicals and deficient technical inspection. These uses have been changing the texture and the physical and chemical composition of the sands with increased effects on the heavy metals accumulation. In order to evaluate the changes, samples of dunes, with and without agricultural uses, were collected and analyzed the chemical and physical parameters. Sieve shakers were used to determine the granulometry and the fine fraction (particles sizes with a diameter less than 0.074 mm); MAB-Peroxide method was used to evaluate the organic matter content. Following electrochemical method it was measured humidity, pH, electrical conductivity and oxidation-reduction. Mineral composition was analyzed by Portable X Ray fluorescence. This study shows an increase trend from natural dune to the agricultural land in the fine particles sizes, organic matter content, humidity, electrical conductivity and oxidation-reduction; pH decreased from basic conditions to an approximately neutral value, thus increasing the risk of metals mobility. A general accumulation of metals in the sand dunes with a special increase in the total concentration of Fe, Mn, Cu, Zn, Pb, As, Zr, Th, Rb, Cr, V, Ni, Hg, Co and U was detected.publishersversionpublishe