Distribution of mercury in the upper sediments from a polluted area (Ria de Aveiro, Portugal)

This work reports levels of Hg, Fe and Mn and sulphides in the upper sediments of the Laranjo Basin, and examines the influence of these elements on the distribution of mercury

Partition, accumulation and speciation of mercury in salt marshes

Doutoramento em QuímicaCom o trabalho desenvolvido nesta tese pretende-se contribuir para um melhor conhecimento do ciclo do mercúrio em sapais; como tal diversos aspectos relacionados com o ciclo biogeoquímico do mercúrio neste tipo de ecossistemas foram abordados, nomeadamente: o impacto que as descargas de mercúrio tiveram nos sapais da baía do Largo do Laranjo bem como o processo de recuperação do sapal (temporal e espacial) pela análise da diversidade do numero de espécies das plantas de sapal e das concentrações de mercúrio no sedimento ao longo do anos; a mobilidade do mercúrio em sedimentos de sapal colonizados pela espécie Halimione portulacoides, a sua distribuição nas camadas de sedimento e a sua incorporação na biomassa subterrânea da planta bem como a potencial exportação de mercúrio do sapal para as áreas adjacentes; o papel das plantas de sapal na conversão de espécies inorgânicas de mercúrio em espécies orgânicas; os processos bioquímicos por detrás do mecanismo de tolerância ao mercúrio da H. portulacoides; avaliação do potencial de uma planta de sapal muito difundida ao longo da costa Portuguesa como biomonitor da contaminação de mercúrio em sedimentos de sapal. A análise dos resultados revelou que as descargas de mercúrio nos sapais da baía do Largo do Laranjo ocorridas no passado induziram uma diminuição na diversidade florística, conduzindo-o a um estado alternativo com a predominância de apenas uma espécie, nos anos de maiores descargas. Após o fim das descargas podemos concluir com base na diversidade do sapal que o sistema demonstra histerese na sua recuperação vindo a recuperar lentamente a sua diversidade florística ao longo dos anos. Em ralação à mobilidade o mercúrio em sedimentos de sapal verificou-se que as taxas de turnover da biomassa subterrânea eram mais elevadas do que as que da biomassa aérea indicando uma maior mobilidade do mercúrio na rizosfera. Tendo em conta o pool de mercúrio encontrado na biomassa aéra verificou-se que a exportação de macro detritos da planta não é significativa para o balanço de mercúrio. Os estudos de especiação de mercúrio realizados nos sedimentos e na biomassa demonstraram que nenhuma outra espécie de mercúrio orgânico foi encontrada para além do MeHg. As concentrações de MeHg nos sedimentos colonizados revelaram-se mais elevadas no entanto as percentagens relativamente aos valores de mercúrio total são baixas. Os resultados sugerem que as plantas de sapal contribuem para a metilação de mercúrio. Os mecanismos de tolerância da H. portulacoides ao mercúrio envolvem essencialmente a sua imobilização nas paredes celulares, contudo o sequestro de mercúrio intracelularmente por fitoquelatinas foi demonstrado neste trabalho. Finalmente demonstrou-se que para além da H. portulacoides ser um bom bioindicador pode também ser usada com um biomonitor da contaminação de mercúrio em sedimentos de sapal.This thesis intends to contribute to the better understand of mercury cycling in salt marsh ecosystems and thus several aspects regarding mercury biogeochemical cycle in salt marshes are discussed, namely the impact of mercury discharges and the recovery processes (temporally and spatially) by the examination of the richness of the species of salt marsh plants and mercury concentrations in sediments over the years; the mobility of mercury in a salt marsh colonised by the species H. and its redistribution in the sediment layers containing plants and subsequently incorporation into below ground biomass, as well the potential export of mercury from the salt marsh to the adjacent areas; the potential role of salt marsh plants on the conversion of inorganic mercury into organic mercury species; the biochemical processes behind mercury tolerance in a salt marsh plant species; the evaluation of the potential role of a well wide distribute salt marsh plant (H. portulacoides) along the Portuguese coast as biomonitor of mercury contamination. The results showed that salt marshes of Laranjo bay shows how a considerable loading of mercury into a salt marsh for four decades has affected its resistance, inducing a change from salt marsh plants species richness into an alternative state dominated by one species. Ten years after the cessation of the loading of mercury and based on the salt marsh plants species richness, the system still shows an incomplete resilience due to the lag in recovery, named hysteresis. With respect to the mercury mobility in the salt marsh sediments, the results shows that the turnover rates for below ground biomass were higher than those observed for above ground biomass, corresponding to higher mercury mobility within H. portulacoides rhizosphere. Taking into account the pool of mercury in above ground biomass, the export of mercury by macro-detritus is not significant for the mercury balance in the studied system. Regarding the mercury speciation studies, no other organic mercury species rather than MeHg were found. MeHg concentrations in the vegetated sediments were higher than in non-vegetated sediments and although the percentages in the sediments were low, comparatively to the total mercury the results suggest that salt marsh plants contribute to methylation in sediments. Mercury tolerance strategies of H. portulacoides seem to involve root cell wall immobilization as a major mechanism of metal resistance, rather than metal chelation in the cytosolic fraction. Intracellular mercury sequestration by PCs in the environment was also demonstrated in this work;however mercury chelation in environmental exposures seems to be a complexed, involving the formation of different types of complexes Finally it was demonstrated that that besides H. portulacoides can be a suitable bioindicator, can also be used as a biomonitor for mercury pollution. Leaves responded following a positive linear model for a contamination range, while roots responded within the sigmoidal model. H. portulacoides may be considered an appealing tool for mercury pollution assessment in salt marshes

Metabolites and biological activities of Thymus zygis, Thymus pulegioides, and Thymus fragrantissimus grown under organic cultivation

Thymus plants are marketed for diverse usages because of their pleasant odor, as well as high nutritional value and wealth of health-promoting phytochemicals. In this study, Thymuszygis, Thymuspulegioides, and Thymusfragrantissimus grown under organic cultivation regime were characterized regarding nutrients and phenolic compounds. In addition, the antioxidant and antibacterial properties of these species were screened. The plants were particularly notable for their high K/Na ratio, polyunsaturated fatty acids content and low omega-6/omega-3 fatty acids ratios, which are valuable features of a healthy diet. Caffeic acid and/or its derivatives, mainly rosmarinic acid and caffeoyl rosmarinic acid, represented the majority of the phenolic constituents of these plants, although they were less representative in T. pulegioides, which in turn was the richest in flavones. The latter species also exhibited the highest antioxidant capacity (DPPH● EC50 of 9.50 ± 1.98 μg/mL and reducing power EC50 of 30.73 ± 1.48 μg/mL), while T. zygis was the most active towards Gram-positive and Gram-negative bacteria. Overall, the results suggest that the three thyme plants grown in organic farming are endowed with valuable metabolites that give them high commercial value for applications in different industries.The authors wish to acknowledge the Foundation for Science and Technology (FCT), the European Union, the National Strategic Reference Framework (QREN), the European Regional Development Fund (FEDER), and Operational Programme Competitiveness Factors (COMPETE), for funding the Organic Chemistry Research Unit (QOPNA) (FCT UID/QUI/00062/2013) and Mountain Research Center (CIMO) (UID/AGR/00690/2013), through national funds and where applicable co-financed by FEDER, within the PT2020 Partnership Agreement. Susana Cardoso wishes to thank the research contract under the project AgroForWealth: Biorefining of agricultural and forest by-products and wastes: integrated strategic for valorisation of resources towards society wealth and sustainability (CENTRO-01-0145-FEDER-000001), funded by Centro2020, through FEDER and PT2020.info:eu-repo/semantics/publishedVersio

Efeito das plantas na acumulação de mercúrio em sedimentos de sapais

Mestrado em Métodos Instrumentais e Controlo de Qualidade AnalíticaCom o objectivo de estudar o efeito das raízes na distribuição de mercúrio em sedimentos de sapais, foram recolhidos cores de sedimentos, com 60 cm de profundidade, em dois sapais da Ria de Aveiro com diferentes graus de contaminação. Os cores foram recolhidos em áreas não colonizadas e em áreas colonizadas pelo Halimione portulacoides e pelo Arthrocnemum fruticosum. Os cores foram seccionados em camadas de 5 cm de espessura e as raízes de cada camada foram separadas dos sedimentos. Para além dos sedimentos, foram também recolhidas folhas e caules das plantas colonizadoras nos dois sapais. Em cada camada de sedimento procedeu-se à determinação da temperatura, pH, matéria orgânica (LOI e Carbono orgânico), humidade, granulometria, biomassa subterrânea, alumínio, ferro e manganês (total e extraído com uma solução de hidroxilamina). As águas intersticiais foram extraídas de cada camada de sedimentos e procedeu-se à determinação de carbono orgânico dissolvido, ferro e manganês, nas mesmas. O mercúrio total foi analisado na fracção sólida do sedimentos e na biomassa subterrânea; nas águas intersticiais foi determinado mercúrio total e reactivo. Na biomassa subterrânea procedeu-se ainda à determinação de ferro e manganês totais. Todas as determinações químicas efectuadas nos sedimentos e nas águas intersticiais dos sedimentos colonizados do sapal contaminado, evidenciam um padrão de distribuição vertical semelhante, caracterizado pela existência de um incremento nas camadas sub-superficiais que contêm maior biomassa subterrânea (entre 10-25 cm de profundidade). Estes perfis contrastam com a uniformidade observada nos perfis verticais dos cores de sedimentos não colonizados. As concentrações máximas de ferro extraído indicam a existência de um zona com natureza óxica favorecendo a precipitação de óxidos e hidróxidos de ferro nas camadas de sedimentos sub-superficiais. As concentrações de mercúrio na fracção sólida e nas águas intersticiais apresentam também incrementos nessas mesmas camadas (max. 39,3 ?g g-1 e 29,3 ng L-1, respectivamente). Estas camadas por sua vez, são enriquecidas em carbono orgânico dissolvido e particulado. As concentrações máximas de mercúrio e ferro ocorrem acima das camadas de sedimentos com maior quantidade de biomassa subterrânea. As concentrações de mercúrio na biomassa subterrânea ocorreram nas mesmas camadas dos sedimentos (max. 120 ? g g-1 para o Halimione portulacoides e 49 ?g g-1 para o Arthrocnemum fruticosum) As concentrações de mercúrio nos sedimentos do sapal menos contaminado, apresentam um perfil semelhante, no entanto as concentrações de mercúrio são mais baixas (max. 1,7 ?g g-1). A biomassa subterrânea nestas camadas apresenta também maiores concentrações de mercúrio (3,2 ?g g-1 para o Halimione portulacoides e 1,5 ? g g-1para o Arthrocnemum fruticosum). Os resultados obtidos apontam para uma intensa mobilização do mercúrio em sedimentos colonizados. O mercúrio é transportado para a zona dos sedimentos com raízes à medida que a planta toma água e é incorporado em óxidos e hidróxidos de ferro formados na rizosfera. Os perfis paralelos de mercúrio dissolvido e carbono orgânico dissolvido observados nas águas intersticiais sugerem um mecanismo de competição entre o carbono orgânico dissolvido e os óxidos e hidróxidos de ferro para a retenção de mercúrio em sedimentos de sapais colonizados. As baixas concentrações de mercúrio registadas na biomassa aérea apontam para o facto da mobilização do mercúrio se processar fundamentalmente entre os sedimentos e as raízes, sendo apenas uma pequena fracção do metal translocada para os órgãos superiores das plantas.In order to examine the effect of roots on mercury distribution in salt-marsh sediments, 60-cm sediment cores were collected in two salt marshes of Ria de Aveiro with different degrees of contamination. Sediment cores were taken in non-vegetated areas and in sediments colonised by Halimione portulacoides and Arthrocnemum fruticosum. Cores were sliced in 5-cm layers. Roots were separated from each sediment layer of the core. Leaves and stems of the two plants from the two marshes were also collected. Temperature, pH, loss on ignition, total organic carbon, pore water content, particle size, belowground biomass, aluminium, total and extracted (hydroxylamine solution) iron and manganese were measured in each sediment layer. Pore waters were extracted from the several sediment layers and organic carbon, iron, manganese determined. Total mercury was analysed in sediment solids and biomass, and reactive and total mercury in pore waters. Total iron and manganese were also analysed in belowground biomass. All chemical determinations in colonised sediments and pore waters from the contaminated site showed a common vertical distribution pattern: sharp increase in the sub-surface layers containing high belowground biomass (between 10 and 25-cm depth). These profiles contrast with the uniformity observed in non-colonised sediment cores. The peak concentration of extractable iron indicates the existence of oxic/suboxic conditions favouring the precipitation of Fe-oxides at sub-surface sediments. Mercury concentrations in solids and pore waters display also sharp increments at the same sub-surface layers (max. 39.3 ? g g-1 and 29.3 ng L-1, respectively). These layers are also enriched in particulate and dissolved organic carbon. Mercury and iron peaks occurred above the higher root biomass. Concentration peaks were registered in sediments colonised by the two plants. Similarly, mercury in roots was higher at the same sediment layers (max 120 ? g g-1 for Halimione portulacoides and 49 ? g g-1 for Arthrocnemum fruticosum). The mercury concentration in the less contaminated site presented a similar profile in the solids, although levels being much lower (max. 1.7 ?g g-1). Roots from these layers showed also higher mercury concentrations: 3.2 for Halimione portulacoides and 1.5 ?g g-1 for Arthrocnemum fruticosum. Our results point to an intense mobilization of mercury in colonised sediments. Mercury is transported to the rooting sediments as plant uptakes water and then incorporated on Fe-oxides formed in the rhizosphere. Parallel concentrations of dissolved mercury and dissolved organic carbon in the sediment pore waters suggest a competition mechanism between organic carbon and Fe-oxides for mercury. Lower mercury concentrations in the aerial biomass point that mercury is mainly cycled between sediment and roots and only a small fraction is translocated to the upper parts

Mercury distribution in Douro estuary (Portugal)

Determinations ofdissolved reactive and total dissolved mercury, particulate and sedimentary mercury, dissolved organic carbon (DOC), particulate organic carbon (POC) and suspended particulate matter (SPM) have been made in the estuary ofriver Douro, in northern Portugal. The estuary was stratified by salinity along most ofits length, it had low concentrations of SPM, typically <20 mg dm-3, and concentrations of DOC in the range <1.0–1.8 mg dm-3. The surface waters had a maximum dissolved concentration of reactive mercury of about 10 ng dm-3, whereas for the more saline bottom waters it was about 65 ng dm-3. The surface waters had maximum concentrations oftotal suspended particulate mercury of ~7 ug g-1 and the bottom waters were always < l ug g-1. Concentrations of mercury in sediments was low and in the range from 0.06 to 0.18 ug g-1. The transport of mercury in surface waters was mainly associated with organic-rich particulate matter, while in bottom waters the dissolved phase transport ofmercury is more important. Lower particulate organic matter, formation ofchlorocomplexes in more saline waters and eventually the presence of colloids appear to explain the difference of mercury partitioning in Douro estuarine waters

Inputs from a mercury-contaminated lagoon: impact on the nearshore waters of the Atlantic Ocean

Ria de Aveiro, a Portuguese coastal lagoon that exchanges water with the Atlantic Ocean, received the effluent from a chlor-alkali industry for over 50 years; consequently several tons of mercury had been buried in the sediments of an inner basin. To assess the importance (and seasonal variation) of the lagoon waters as carriers of mercury to the nearby coastal area, we measured total mercury levels in several compartments: in surface sediments, in surface and deep waters (including dissolved and particulate matter!, and in biota. Dissolved (reactive and total) mercury concentrations both in surface and deep waters were low (<1 to 15 ng L '). Mean mercury values in suspended particulate matter varied hetween 0.2 and 0.6 jxg g ' and in sediments between 1 and 9 ng g '. Aquatic organisms displayed levels below regulatory limits but exhibited some bioaccumulation of mercury, with concentrations ranging from 0.05 to 0.8 ^ig g ' Idry weight (dw)|. No seasonal pattern was found in this study for mercury-related determinations. Levels found in the estuary mouth during ebb tide provide evidence for the transport of mercury to the coastal zone. No significant changes in the partition of mercury between dissolved and particulate phases were found in the coastal waters in comparison with the values found in the estuary mouth. In spite of the high levels of mercury found inside some areas of the lagoon, the wide web of islands and channels allows some spreading of contaminants before they reach the coastal waters. Moreover, the low efficiency of local marine sediments in trapping mercury contributes to a dilution of mercury transported in suspended particulate matter over a broader area, reducing the impact in the nearby manne coastal zone.A Ria de Aveiro, um sistema aquático situado na costa Atlántica Portuguesa, eKteve siyeita durante 50 anos à descarga do efluente de urna industria de cloni e .soda cáustica, o que provocou a deposiçâo de toneladas de mercurio nos sedimentos de urna bacia de sedimentaçào situada na proximidadr dn de.scarga. Para avaliar a importancia das aguas estuariiias como transportadoras de mercurio para a zona costeira adjacente, examinaram-se em varias campanhas realizadas em diferentes épocas do ano. os níveis de mercurio total em diversos compartimentos: .sedimentos superficiais, aguas de superficie e de profundidade (na fracçâo dissolvida e particulada) e em organismos marinhoe. As concentraçôes de mercurio dissolvido (reactivo e total) foram baixaa quera superficie, quer em profundidade «1 a 15 ng L '). Na materia particulada em suspensao os valores medios de concentraçâo variaram entre 0.2 e 0.6 ng g ' e nos sedimentos apenas entre I e 9 ng g '.Os organismos estudados ( peixes e bivalves), com concentraçôes numa gama entre 0.05 e 0.8 (peso seco) (ig g ', apresentaram níveis inferiores aos limites legáis aplicáveis mas demonstraram bioacumuîaçào de mercurio. OB resultados obtidos nos diversos compartimentos estudados nao revelaram a existencia de padrôes sazonáis na variaçâo das concentraçôes de mercurio. Os níveis de metal encontrados à saida do estuario durante a vazante, evidenciam o transporte de mercurio para a zona costeira. Nao foi observada uma alteraçào significativa na partiçâo do metal entre as fraccóea dissolvida e particulada na zona costeira atrácente relativamente ao observado à saída do estuario. Apesar dos niveis elevados de mercurio presentes no interior do sistema aquático, a complexa e extensa rede de ilbas e cañáis, dificulta a circulaçào da agua permitindo alguma dispersao dos contaminantes antes de atingirem a zona costeira. Além disso, a baixa capacidade dos sedimentos costeiros locáis para aprisionar mercurio contribui para a diluiçâo, numa zona mais vasta, do metal transportado associado à materia suspensa particulada, reduzindo assim o impacto na área adjacente à saída da laguna

Phenological development stages variation versus mercury tolerance, accumulation, and allocation in salt marsh macrophytes Triglochin maritima and Scirpus maritimus prevalent in Ria de Aveiro coastal lagoon (Portugal)

Efficient and sustainable management of rapidly mounting environmental issues has been the focus of current intensive research. The present study aimed to investigate the impact of plant phenological development stage variation on mercury (Hg) tolerance, accumulation, and allocation in two salt marsh macrophytes Triglochin maritima and Scirpus maritimus prevalent in historically Hg-contaminated Ria de Aveiro coastal lagoon (Portugal). Both plant samples and the sediments vegetated by monospecific stands of T. maritima and S. maritimus were collected from reference (R) and sites with moderate (M) and high (H) Hg contamination in Laranjo bay within Ria de Aveiro lagoon. Hg tolerance, uptake, and allocation in T. maritima and S. maritimus, physico-chemical traits (pH, redox potential, and organic matter content) and Hg concentrations in sediments vegetated by these species were impacted differentially by phenological development stages variation irrespective of the Hg contamination level. In T. maritima, Hg concentration increased with increase in Hg contamination gradient where root displayed significantly higher Hg followed by rhizome and leaf maximally at H. However, in S. maritimus, the highest Hg concentration was perceptible in rhizome followed by root maximally at M. Between the two studied plant species, S. maritimus displayed higher Hg tolerance index (depicted by higher plant dry mass allocated to reproductive stage) and higher available Hg at M (during all growth stages) and H (during senescent stage) when compared to T. maritimus. Both plant species proved to be Hg excluder (low root/rhizome-leaf Hg translocation). Additionally, T. maritima also acted as Hg stabilizer while, S. maritimus as Hg accumulator. It can be inferred from the study that (a) the plant phenological development stage variations significantly influenced plant Hg sensitivity by impacting sediment chemistry, plant growth (in terms of plant dry mass), Hg accumulation, and its subsequent allocation capacity, contingent to Hg contamination gradient; (b) S. maritimus accumulated higher Hg but restricted its translocation to above-ground part using exclusion process at both M and H due to its accelerated growth during Hg-tolerant reproductive/metabolically active phenological development stage greater than its counterpart T. maritima; and (c) the studied salt marsh plants although hailed from the same C3 and monocot group did not necessarily display similar phenotypic plasticity and behavior towards Hg-contaminated scenario during their life cycle.publishe

Valuable Nutrients from Ulva rigida: Modulation by Seasonal and Cultivation Factors

Ulva macroalgae species are recognized to be an underexploited source of key nutrients, including proteins, fibers and minerals. The present work evaluated the nutritional value protein, ash, mineral composition, fat, fatty acid profile and dietary fiber of the green macroalgae Ulva rigida produced in an open land-based integrated multi-trophic aquaculture (IMTA) system, over four seasons. Overall, protein and fat content of the farmed algae ranged between 7.6 and 25.8% DW and between 0.2 and 1.3% DW, respectively, reaching the highest levels during autumn/winter seasons. In turn, total dietary fiber and ashes showed a contrary seasonal tendency, reaching maximum levels in spring (40.9–58.3% DW and 25.5–38.8% DW, respectively). Notably, the latter were particularly characterized by their richness in potassium, magnesium and iron, and a sodium/potassium ratio bellow 1.7. Variable cultivation conditions of stocking density (Sd) and flow rate (Fr) were also tested, allowing to confirm that manipulation of cultivation conditions in an IMTA system may help to improve the nutritional value of this macroalga and to boost its market value through its use as a functional food ingredient

Inter‐Individual versus Inter‐Population Variability of Calendula suffruticosa subsp. algarbiensis Hexane Extracts

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Metabolite Profiling, Antioxidant and Key Enzymes Linked to Hyperglycemia Inhibitory Activities of Satureja hispidula: An Underexplored Species from Algeria

In the present study, two extracts from the aerial parts of the endemic species Satureja hispidula were analyzed for the first time by ultra-high-performance liquid chromatography coupled with a diode array detector and an electrospray mass spectrometer (UHPLC-DAD-ESI/MS) method in order to identify and quantify their phenolic compounds. These extracts&rsquo; antioxidant, &alpha;-glucosidase and &alpha;-amylase inhibitory activities were also evaluated. UHPLC-DAD-ESI/MS allowed the identification of 28 and 20 compounds in the ethanolic and aqueous extracts, respectively; among them, 5-O-caffeoylquinic acid was the most abundant in both extracts. The biological assay results indicate that the species S. hispidula, besides its high antioxidant power, is also potentially useful for inhibiting the &alpha;-glucosidase enzyme. In both antioxidant and &alpha;-glucosidase inhibitory assays, the aqueous extract exhibited the most promising results, significantly better than the standards used as positive controls