A method for the assessment of long-term changes in carbon stock by construction of a hydropower reservoir

Sustainability of hydropower reservoirs has been questioned since the detection of their greenhouse gas (GHG) emissions which are mainly composed of carbon dioxide and methane. A method to assess the impact on the carbon cycle caused by the transition from a natural river system into a reservoir is presented and discussed. The method evaluates the long term changes in carbon stock instead of the current approach of monitoring and integrating continuous short term fluxes. A case study was conducted in a subtropical reservoir in Brazil, showing that the carbon content within the reservoir exceeds that of the previous landuse. The average carbon sequestration over 43 years since damming was 895 mg C m\(^{-2}\mathrm{{day}}^{-1}\) and found to be mainly due to storage of carbon in sediments. These results demonstrate that reservoirs have two opposite effects on the balance of GHGs. By storing organic C in sediments, reservoirs are an important carbon sink. On the other hand, reservoirs increase the flux of methane into the atmosphere. If the sediments of reservoirs could be used for long term C storage, reservoirs might have a positive effect on the balance of GHGs.     

Older can be better: physiological costs of paternal investment in the Florida scrub-jay

In species that undergo actuarial senescence, the value of current reproduction is predicted to increase relative to the value of future reproduction with age, as the probability of survival to another reproductive event is reduced. Therefore, life history theory predicts that aging animals should increase their investment in reproduction. However, an increase in reproductive investment may carry significant costs to the breeding individuals. We recorded provisioning rates of Florida scrub-jay male breeders, followed by their immediate capture to assess body condition and collect blood for an in vitro test of immunocompetence and an assay of baseline corticosterone for a measure of stress. Older males provisioned offspring and brooding mates at the highest rates. There was no evidence of any physiological deficits in males with high provisioning rates, independent of age. It appears that birds that survive to old age are high quality birds that maintain good physiological condition, which complements the value of experience and permits maximal investment in offspring.     

Assessing the capacity of three Bolivian food systems to provide farm-based agroecosystem services

ABSTRACT

Food system activities have modified 40% of the Earth’s terrestrial surface. These activities affect the sustainability of food systems – and their ability to provide agroecosystem services. Here, we compare three food systems in Bolivia. One is agro-industrial (soybean), one is indigenous to a Guarani community (maize and beans), and one is an agroecological, horticulture-based food system. We use the Agroecosystem Service Capacity (ASC) approach, which is based on a list of 23 agroecosystem services that allow the ASC index of farm-based agroecosystems to be estimated. Our findings show that agroecological (ASC = 2.57) and indigenous (ASC = 2.43) farm-based agroecosystems have a higher capacity to provide farm-based agroecosystem services than the agro-industrial (ASC = 0.82). This capacity differs because farmers in the agroecological and indigenous farm-based agroecosystems achieve a higher structural diversity and know how to use more agroecosystem services. These results could promote more sustainable food systems by fostering agricultural landscapes that provide a diversity of farm-based agroecosystem services.     

Environmental scanning electron microscopy as a new technique to determine the hygroscopic behaviour of individual aerosol particles

The hygroscopic behaviour of NaCl, (NH₄)₂SO₄, Na₂SO₄ and NH₄NO₃ particles in the size range of 0.1–20 μm was studied by environmental scanning electron microscopy (ESEM). This technique allows the in-situ observation of individual aerosol particles while changing the temperature and/or relative humidity (RH) in the sample chamber. The hygroscopic behaviour of these particles (e.g., deliquescence, adsorption of water on the particle surface) becomes directly observable with a lateral resolution of the order of 8–15 nm. The deliquescence relative humidities (DRH) of the different salts, the temperature dependence of the DRH for NH₄NO₃, and the growth factors (at increasing relative humidities) for NaCl were determined. Generally, a good agreement between the values obtained by ESEM and those found in literature was achieved. However, the DRH of NaCl determined by ESEM is systematically higher (approximately 2%, absolute) than the values obtained by other techniques, which can be explained by the observed strong absorption of water onto the crystal surface prior to droplet formation. The efflorescence behaviour of individual particles can be studied only qualitatively due to influences of the sample substrate. Furthermore, it is demonstrated that the activation of soot can be studied at high resolution by ESEM.     

Antioxidant and biotransformation enzymes in Myriophyllum quitense as biomarkers of heavy metal exposure and eutrophication in Suquía River basin (Córdoba, Argentina)

We report the evaluation of changes in water quality, increasing pollution level, of a section of Suquía River basin (Córdoba, Argentina) by using Myriophyllum quitense as bioindicator in addition to the measurement of chemical parameters, combined with chemometrics (ANOVA, Cluster and Discriminant Analysis). Myriophyllum quitense was collected upstream from Córdoba city at an unpolluted site of Suquía River basin. After collection plants were transplanted to different sites with different pollution levels. Subsequent to transplantation plants were weekly collected from the original site as well as from transplantation stations. Water quality was evaluated throughout the transplantation experiment, while the use of this macrophyte as bioindicator was verified through the activation of its antioxidant defenses and biotransformation system. Myriophyllum quitense reacts to the pollution stress increasing the activity of glutathione-S-transferases (CDNB and Fluorodifen), glutathione reductase (GR) and peroxidase (POD). Elevated enzyme activities agreed to different pollution levels, especially inorganic nitrogen loads combined with elevated lead and aluminum concentrations, all of them originated by anthropogenic activities, thus presenting Myriophyllum quitense as a good biomonitor for assessment of water quality in this polluted aquatic ecosystem.     

Surface runoff and transport of sulfonamide antibiotics and tracers on manured grassland

Despite their common use in animal production the environmental fate of the veterinary sulfonamide antibiotics after excretion is only poorly understood. We performed irrigation experiments to investigate the transport of these substances with surface runoff on grassland. Liquid manure from pigs treated with sulfadimidine was spiked with sulfadiazine, sulfathiazole, the herbicide atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine), and the conservative tracer bromide and spread onto eight plots. Four plots received the same amounts of the spiked substances in aqueous solution (controls). Apart from the application matrix we varied the time between application and irrigation. Manure increased the runoff volume up to six times compared with the controls. It seemed that manure enhanced the runoff by sealing the soil surface. On manured plots the relative antibiotic concentrations in runoff were higher than on the controls, reaching an average of 0.3% (sulfadiazine), 0.8% (sulfathiazole), and 1.4% (sulfadimidine) of the input concentrations after a 1-d contact time. The corresponding values on the controls were 0.16% for sulfadiazine and 0.08% for sulfathiazole. After 3 d, the maximum values on the manured plots were even higher, whereas they had fallen below the limit of quantification on the controls. As a consequence, the sulfonamide losses were 10 to 40 times larger on the manured plots. The relative mobility of the sulfonamides on the control plots followed the trend expected from their chromatographic separation but the opposite was found on the manured plots. Hence it is important to consider explicitly the physical and chemical effects of manure when assessing the environmental fate of sulfonamides.     

Kosovo-Konflikt: ?kologische Auswirkungen

Zusammenfassung  Der WWF (World Wide Fund for Nature), Initiator und Tr?ger des Donau-Karpaten-Programms, besch?ftigt sich seit Beginn des Kosovo-Konfliktes mit den Auswirkungen der kriegerischen Auseinandersetzungen auf Natur und Mensch und versucht, die Welt?ffentiichkeit entsprechend zu informieren. Ende Juli 1999 hat der WWF International eine Mission, bestehend aus unabh?ngigen Toxikologinnen und ?lexperten, an die Donau entsandt. Unter der Leitung von Philip Weller, dem Direktor des WWF Donau-Karpaten-Programms, wurden drei Tag lang Industriekomplexe besichtigt und Gespr?che mit Betroffenen geführt. Die Reise führte das Team nach Panćevo und Novi Sad, und damit zu den Schwerpunkten der zerst?rten Chemie- und Petrochemischen Komplexe. In den betroffenen Werken, HIP AZOTARA, Panćevo und NIS ?lraffinerie, Novi Sad wurde das Team von den jeweiligen Werkleitern geführt. Gespr?che fanden statt mit dem Bürgermeister von Panćevo und Vertretern des Gesundheitsamtes in Belgrad. Es war dem Team m?glich, Boden- und Wasserproben zu nehmen und zu analysieren. Damit liegen den Autoren unabh?ngige Analysenergebnisse vor, die es gestatten, eine erste, orientierende Einsch?tzung der Kontaminationen vorzunehmen.