Browsing by Author "Varennes, A."
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- Amendment of an acid mine soil with compost and polyacrylate polymers enhances enzymatic activities but may change the distribution of plant speciesPublication . Varennes, A.; Queda, Cristina Cunha; Guiwei, QuMany soils derived from pyrite mines spoils are acidic, poor in organic matter and plant nutrients, contaminated with trace elements, and support only sparse vegetation. The establishment of a plant cover is essential to decrease erosion and the contamination of water bodies with acid drainage containing large concentrations of trace elements. We tested the application of compost and polyacrylate polymers to promote the growth of indigenous plant species present in the mine area. Soil treatments consisted of unamended soil (control), soil with mineral fertilizers only, soil with fertilizer plus compost, soil with fertilizer plus polyacrylate polymers, and soil with fertilizer plus both amendments. Half of the soil was grown with Briza maxima L.(greater quaking grass), Chaetopogon fasciculatus (Link) Hayek (chaetopogon), and Spergularia purpurea(Persoon) G. Don fil. (purple sandspurry),while the remainder was left bare. In the absence of plants, the greatest improvements in soil conditions were obtained by the application of both amendments,which was associated with the greatest values of protease, acid phosphatase, and β-glucosidase, whereas the activity of cellulase and microbial respiration were similar in soil amended with compost or polymer. Dehydrogenase activity was greatest in soil with compost (with or without polymer), whereas urease activity was impaired by both amendments. In the presence of plants, the application of both amendments led to the greatest activities of protease,urease, β-glucosidase, cellulase, and microbial respiration, but acid phosphatase was mainly enhanced by polymer and dehydrogenase was increased by compost. Plant growth was stimulated in all treatments compared with unamended soil, but the greatest value for total accumulated biomass was obtained in fertilized soil receiving both amendments. However, species responded differently to treatment: while the growth of B. maxima was greatest in soil with compost and polymer, the growth of C. fasciculatus responded better to soil with compost, and S. purpurea grew better in polymer-amended soil. The amendments tested improved the quality of a mine soil and stimulated plant growth. However, botanical composition likely changes over time with amendments, and this needs to be considered when a large scale application of amendments is projected.
- Assessment of chemical, biochemical and ecotoxicological aspects in a mine soil amended with sludge of either urban or industrial originPublication . Alvarenga, P.; Palma, P.; Gonçalves, A.P.; Baião, N.; Fernandes, R.M.; Varennes, A.; Vallini, G.; Duarte, E.; Cunha-Queda, A.C.A greenhouse pot experiment was conducted to evaluate the effect of sewage sludge (SS), of sugar beet sludge (SBS), or of a combination of both, in the remediation of a highly acidic (pH 3.6) metal-contaminated soil, affected by mining activities. The SS was applied at 100 and 200 Mg ha 1 (dry weight basis), and the SBS at 7 Mg ha 1. All pots were sown with Italian ryegrass (Lolium multiflorum Lam.). After 60 d of growth, shoot biomass was quantified and analysed for Cu, Pb and Zn. The pseudo-total and bioavailable contents of Cu, Pb and Zn and the enzymatic activities of b-glucosidase, acid phosphatase, cellulase, protease and urease were determined in the soil mixtures. Two indirect acute bioassays with leachates from the soil (luminescent inhibition of Vibrio fischeri and Daphnia magna immobilization) were also used. The SS, in particular when in combination with SBS, corrected soil acidity, while increasing the total organic matter content and the cation exchange capacity. The application of SS led to a decrease in the level of effective bioavailable metals (extracted by 0.01 M CaCl2, pH 5.7, without buffer), but caused an increase in their potential bioavailability (extracted by a solution of 0.5 M NH4CH3COO, 0.5 M CH3COOH and 0.01 MEDTA, pH 4.7). Plant biomass increased more than 10 times in the presence of 100 Mg SS ha 1, and more than five times with the combined use of 100 Mg SS ha 1 and SBS, but a considerable phytotoxic effect was observed for the application rate of 200 Mg SS ha 1. Copper, Pb and Zn concentrations in the shoots of L. multiflorum decreased significantly when using 100 Mg SS ha 1 or SBS. The activities of b-glucosidase, urease and protease increased with increasing SS applications rates, but cellulase had a reduced activity when using 200 Mg ha 1 SS. Both amendments were able to suppress soil toxicity to levels that did not affect D. magna, but increased the soil leachate toxicity towards V. fischeri, especially with the application of 200 Mg SS ha 1. This study showed that for this type of mine soils, and when using SS of similar composition, the maximum SS application rate should be 100 Mg ha 1, and that liming the SS amended soil with SBS did not contribute to a further improvement in soil quality.
- O azoto no crescimento e na produtividade de jovens pereiras 'Rocha'Publication . Varennes, A.; Neto, C.; Carranca, C.; Rocha, I.; Sobreiro, J.; Clemente, J.Pear trees (Pyrus communis L. ‘Rocha’) grafted on quince ‘BA29’ were planted in February of 2003 at “Pêro Moniz” (“Cadaval”, Portugal) and drip-fertigated for three years with four N levels (0, 10, 20 and 40 kg N/ha per year) using ammonium nitrate. At planting and at the end of each season, tree height (A), trunk cross sectional area (AST) and the number of shoots and shoot length (NL and CL) were determined. Leaves were collected 110 days after full bloom (DAPF) and at leaf fall and were chemically analysed for N. The onset of flowering was in 2005 and in that year the fruit set and the yield characteristics were evaluated. Moreover, in 2005 five extra trees were selected for each N level, and all flowers were collected and analysed. Most growthcharacteristics were irresponsive to N fertilization. In the third year the AST differed between N levels, whereas CL responded to N supply at the end of the first year of fertilization. The leaves N concentration varied in response to N supply. The control presented fewer flowers and the highest N level resulted in a greater flower production. Flower N concentration was lower at the intermediate N levels. Fruit set and yield were not significantly different between N treatments. Fruits from the highest N level presented lower pulp firmness and a bigger starch regression index, indicating a more advanced maturation stage than the fruits from other N levels.
- A caracterização e correção da deficiência de ferro em plantas de morangueiro: novas abordagensPublication . Pestana, Maribela; Gama, Florinda; Saavedra, Teresa; Pinto, João Castro; Abadia, Anunciación; Varennes, A.; Correia, Pedro JoséIron (Fe) is abundant in soils and although it is required in small amounts by plants the incidence of iron chlorosis (Fe deficiency) is very common in a number of crops and requires massive soil application of Fe-chelates to correct it. In this work, we present the most important results obtained in several experiments conducted with strawberry to study the physiological and biochemical response mechanisms to Fe deficiency, and the assessment of novel alternatives to control this nutritional disorder. In all experiments, conducted in hydroponic systems, symptoms were induced by withdrawing Fe from the solution and the results were compared to a control treatment grown with Fe. The degree of chlorosis and symptoms recovery was estimated using SPAD values. The activity of iron chelate reductase, the enzyme responsible for Fe reduction in roots, was determined in root apices by colorimetric quantification of the BPDS complex. The Fe concentration in leaves and roots was quantified by atomic absorption spectrophotometry after treatments at 450 ºC and acid digestion of the ashes obtained. Strawberry plants that grew always without Fe, presented Fe chlorosis and morphological external root modifications associated with increases of the activity of the Fe-reductase enzyme. The recovery of chlorotic plants was achieved by application of Fe sulphate either to leaves or to the nutrient solution. In plants recovered by using Fe in the solution, the enzyme maintained a large activity, suggesting a strategy to increase plant Fe pools. As an alternative to synthetic Fe chelates, we also tested a foliar application of a plant extract obtained from fresh grass clippings (national patent PT/103584-2009 of UALG, and international patent PCT/PT2007/000041-2008, UALG and ADPFertilizantes), which was effective in chlorosis recovery after three applications. The results are discussed in order to highlight the practical implications of these responses under a perspective of optimization of crop Fe fertilization
- Clorose férrica induzida pelo calcárioPublication . Pestana, Maribela; Varennes, A.; Correia, Pedro JoséIron chlorosis is one of the most common and difficult to control problems in crops grown on calcareous soils. In alkaline soils, which represent one third of the Earth surface, the bicarbonate ion prevails and is a major induction factor of iron chlorosis. As a result, alkalinity limits Fe bioavailability in the soil solution, Fe reduction and assimilation, as well as transport and uptake within the plant. Due to this nutritional imbalance, plants develop different response strategies which are not entirely successful on calcareous soils. In consequence, yield, fruit quality and harvesting season are negatively affected. Preventing and treating iron chlorosis is highly costly, but is inevitable, in order to ensure crop sustainability in regions where soil calcium carbonate and aridity are limiting factors. In this work, we present a short overview of Fe dynamics in calcareous soils and its influence on crop productivity
- Comparação de correctivos aplicados a um solo de uma área mineira contaminado com arsénio e seu efeito no crescimento de plantasPublication . Madeira, A.C.; Esteves, C.; Abreu, M.M.; Varennes, A.; Magalhães, M.C.F.Three amendments (iron oxides, Fe; organic matter, MO; calcium phosphate, PCa) were applied to a naturally contaminated soil with arsenic and their effect on the growth of tomato plants and Italian parsley was studied. The results indicate differences associated with the availability of arsenic in the soil in the presence of amendments: Fe had no influence on arsenic availability compared with the unamended soil, while MO and PCa increased the avalability of arsenic.
- A contribution towards the risk assessment of soils from the São Domingos mine (Portugal): chemical, microbial and ecotoxicological indicatorsPublication . Alvarenga, Paula; Palma, Patrícia; Varennes, A.; Queda, C. CunhaThis study is a contribution towards a risk assessment of the São Domingos Mine area (Portugal), integrating information from: soil physicochemical characteristics, pseudo-total and bioavailable trace elements (As, Cd, Cr, Cu, Ni, Pb and Zn), ecotoxicological evaluation, and microbial indicators. The bioassays using soil eluates (seed germination, luminescent inhibition of Vibrio fischeri and Daphnia magna immobilization) confirmed the soil toxicity categorization obtained with the bioassays using soil (plant growth tests, Eisenia fetida mortality and avoidance behaviour). However, the soil identified as the most toxic using bioassays, was different from the expected when considering the results from pseudototal and effective bioavailable trace elements. Taking in consideration the observations, it is highly recommended to complement the results from environmental chemistry with results from bioassays, in order to provide a more complete and relevant information on the bioavailability of contaminants and to characterize the risk of contaminated soils.
- Development and recovery of iron deficiency by iron resupply to roots or leaves of strawberry plantsPublication . Pestana, Maribela; Correia, Pedro José; Saavedra, Teresa; Gama, Florinda; Abadia, Anunciación; Varennes, A.Bare-root transplants of strawberry (Fragaria ananassa Duch. cv. ‘Selva’) were transferred to nutrient solutions with or without iron (Fe). After six weeks of growth, plants grown in solution lacking Fe were chlorotic and showed morphological changes in roots typical of Fe deficiency. Subsequently, four treatments were applied for nine days: plants grown in continued absence of Fe (Fe0); plants grown in continued presence of 10 mM Fe (Fe10); foliar application of ferrous sulphate every two days to chlorotic plants (Fe-leaves); and growth of chlorotic plants in solution with ferrous sulphate (Fe-solution). After six days, the chlorophyll (Chl) content in leaves of Fe-solution plants was similar to that in Fe10 plants. Under the Fe-leaves treatment, a slight regreening of new leaves was observed only by the end of the experiment. After nine days, ferric chelate reductase (FC-R) activity was unchanged in Fe10 but increased in Fe0 plants. The FC-R activity of Fe-solution plants was similar to the initial value for chlorotic plants, whereas it was reduced drastically under the Fe-leaves treatment. The Fe concentration in leaves of Fe0 and Fe10 was similar, whereas the Fe-solution and Fe-leaves treatments enhanced leaf Fe concentration. In contrast to the Fe-solution treatment, foliar application of Fe did not increase the Fe concentration in roots. Under our experimental conditions, FC-R activity in strawberry appeared to be deactivated rapidly by pulses of Fe applied by foliar sprays. Deactivation was slower if Fe was applied directly to roots, which suggested that the plants had greater opportunity to take Fe.
- Estabilidade de aspartato-aminotransferases de folhas de Lupinus albus L. cv. Estoril em extractos não purificadosPublication . Louro Martins, Luisa; Mourato, Miguel; Girio, F.M.; Varennes, A.
- Evaluation of amendments in the rehabilitation of sulfide mine tailings from São DomingosPublication . Abreu, M.M.; Varennes, A.; Santos, E.S.; Macias, F.The São Domingos mining area is located in the Iberian Pyrite Belt, SE Portugal, and represents a serious environmental hazard (Matos and Martins, 2006). Exploitation dated back to pre-roman and roman times with extraction of Ag, Au and Cu exploitation, mainly in the gossan (resulting from the ore weathering). The intense exploitation started in the middle of 19th century, both in the gossan and sulfide ore-containing Cu, Zn, As and Pb, and lasted until 1960, with the exhaustion of the ore (Quental et al., 2002). Different types of waste materials were left: gossan, host rocks (volcanic with shales, and shales), roman and modern slags, smelting ashes and brittle and blocks of pyrite (Matos, 2004; Álvarez-Valero et al., 2008). All sulfide mine wastes are typically heterogeneous and contain high amounts of trace elements, acidic pH and small contents of organic matter and nutrients. The large dumps containing pyrite and other metal sulfides generate, by oxidation, acidic mine drainage (AMD) which increases the availability of trace elements for microorganisms and plants in the surrounding soils. All of these characteristics contribute towards a system that is barely capable of supporting the establishment or survival of plants. The use of amendments and spontaneous colonization (vegetation) from mining areas (phytostabilization) are cost-effective and environmentally sustainable methods to rehabilitate these contaminated and degraded areas even in arid and semi-arid conditions (Tordoff et al., 2000; Mendez and Maier, 2008). Thus, the preparation of Technosols from mixtures of organic and inorganic wastes can be an attractive option to rehabilitate mining areas because they can improve physical, chemical and biological properties contributing, at the same time, towards a strategy of wastes valorisation (Macías, 2004). The use of mixtures composed of residues with different C:N ratios can be used to manipulate the rate of mineralization. Nevertheless, the amendments used should also promote other soil functions (Arbestain et al., 2008). The objective of this study was to evaluate the influence of cost-effective organic and inorganic amendments, available in the region, in the rehabilitation of sulfide materials from the São Domingos mine area
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