Publications (122) View all
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Article: Influence of canopy budget model approaches on atmospheric deposition estimates to forests
Biogeochemistry 04/2013; · 3.07 Impact Factor -
Article: Importancia ecológica de parásitos (Nematomorpha: Gordiida) en arroyos de montaña
Revista Chilena de Historia Natural 04/2013; 86(1):107-111. -
Article: The response of the foliar antioxidant system and stable isotopes (δ(13)C and δ(15)N) of white willow to low-level air pollution.
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ABSTRACT: In this study we aimed to determine and elucidate the effect of ambient air pollution on the foliar antioxidant system and stable carbon and nitrogen isotopes of white willow (Salix alba L.). We grew white willow in uniform potting soil in the near vicinity of sixteen air quality monitoring stations in Belgium where nitrogen dioxide (NO2), ozone, sulfur dioxide and particulate matter concentrations were continuously measured. The trees were exposed to ambient air during six months (April-September 2011), and, thereafter, the degree of lipid peroxidation and foliar content of antioxidant molecules (ascorbate, glutathione, polyphenols, flavonoids), antioxidant enzymes (superoxide dismutase, ascorbate peroxidase, peroxidase) and foliar stable carbon (δ(13)C) and nitrogen (δ(15)N) isotopes were measured. We found that lipid peroxidation was caused by air pollution stress, arising from high ambient NO2 concentrations, as shown by an increased amount of malondialdehyde. The antioxidant system was activated by increasing the amount of polyphenols at monitoring stations with a high atmospheric NO2 and low O3 concentration, while no increase of key enzymes (e.g., ascorbate, glutathione) was observed. The δ(13)C also decreased with increasing NO2 concentrations and decreasing O3 concentrations, probably reflecting a decreased net photosynthesis and/or a concomitant decrease of (13)CO2 in the atmosphere. Shade also influenced foliar δ(13)C and the content of leaf ascorbate and glutathione.Plant Physiology and Biochemistry 03/2013; 67C:154-161. · 2.84 Impact Factor -
Article: Effects of two contrasting hemiparasitic plant species on biomass production and nitrogen availability.
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ABSTRACT: Hemiparasitic plants can substantially change plant community structure; the drainage of host resources has a direct negative effect on host biomass and, as a consequence, promotes non-host biomass production (parasitism pathway); on the other hand, hemiparasitic litter inputs can enhance nutrient cycling which may have an indirect positive effect on both host and non-host biomass production (litter pathway). We evaluated the net effect of both pathways on total shoot biomass (with and without the hemiparasite) and shoot biomass of graminoids, forbs and ericaceous shrubs using a removal experiment in three sites infested with the annual Rhinanthus angustifolius, and three sites infested with the biennial Pedicularis sylvatica. We addressed the potential importance of litter effects by determination of litter quantity and quality, as well as modeling N release during decomposition. In the second year after removing the hemiparasites, total plant biomass at Rhinanthus sites was 24 % higher in weeded plots than in control plots, while weeding had no significant effect at Pedicularis sites. The increase in total biomass following Rhinanthus removal was mainly due to a higher biomass of graminoids. The amount of litter produced by Rhinanthus was only half of that produced by Pedicularis; N contents were similar. The amount of N in the litter was 9 and 30 % of the amount removed by mowing for Rhinanthus and Pedicularis sites, respectively. Within 2 months, about 45 % of the N in both hemiparasitic litter types was released by decomposition. Our results suggest that in addition to the suppression of host biomass due to parasitism, positive litter feedbacks on host and non-host biomass-via an increase in nutrient availability-also affect plant community structure. We propose that, depending on the particular hemiparasite and/or site conditions, these positive litter feedbacks on shoot biomass can compensate for the negative effect of parasitism.Oecologia 03/2013; · 3.41 Impact Factor -
Article: One-stage partial nitritation/anammox at 15 °C on pretreated sewage: feasibility demonstration at lab-scale.
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ABSTRACT: Energy-positive sewage treatment can be achieved by implementation of oxygen-limited autotrophic nitrification/denitrification (OLAND) in the main water line, as the latter does not require organic carbon and therefore allows maximum energy recovery through anaerobic digestion of organics. To test the feasibility of mainstream OLAND, the effect of a gradual temperature decrease from 29 to 15 °C and a chemical oxygen demand (COD)/N increase from 0 to 2 was tested in an OLAND rotating biological contactor operating at 55-60 mg NH(4) (+)-N L(-1) and a hydraulic retention time of 1 h. Moreover, the effect of the operational conditions and feeding strategies on the reactor cycle balances, including NO and N(2)O emissions were studied in detail. This study showed for the first time that total nitrogen removal rates of 0.5 g N L(-1) day(-1) can be maintained when decreasing the temperature from 29 to 15 °C and when low nitrogen concentration and moderate COD levels are treated. Nitrite accumulation together with elevated NO and N(2)O emissions (5 % of N load) were needed to favor anammox compared with nitratation at low free ammonia (<0.25 mg N L(-1)), low free nitrous acid (<0.9 μg N L(-1)), and higher DO levels (3-4 mg O(2) L(-1)). Although the total nitrogen removal rates showed potential, the accumulation of nitrite and nitrate resulted in lower nitrogen removal efficiencies (around 40 %), which should be improved in the future. Moreover, a balance should be found in the future between the increased NO and N(2)O emissions and a decreased energy consumption to justify OLAND mainstream treatment.Applied Microbiology and Biotechnology 02/2013; · 3.42 Impact Factor
