Potential nitrification and denitrification on different surfaces in a constructed treatment wetland

Improved understanding of the importance of different surfaces in supporting attached nitrifying and denitrifying bacteria is essential if we are to optimize the N removal capacity of treatment wetlands. The aim of this study was therefore to examine the nitrifying and denitrifying capacity of different surfaces in a constructed treatment wetland and to assess the relative importance of these surfaces for overall N removal in the wetland. Intact sediment cores, old pine and spruce twigs, shoots of Eurasian watermilfoil (Myriophyllum spicatum L.), and filamentous macro-algae were collected in July and November 1999 in two basins of the wetland system. One of the basins had been constructed on land that contained lots of wood debris, particularly twigs of coniferous trees. Potential nitrification was measured using the isotope-dilution technique, and potential denitrification was determined using the acetylene-inhibition technique in laboratory microcosm incubations. Nitrification rates were highest on the twigs. These rates were three and 100 times higher than in the sediment and on Eurasian watermilfoil, respectively. Potential denitrification rates were highest in the sediment. These rates were three times higher than on the twigs and 40 times higher than on Eurasian watermilfoil. The distribution of denitrifying bacteria was most likely due to the availability of organic material, with higher denitrification rates in the sediment than on surfaces in the water column. Our results indicate that denitrification, and particularly nitrification, in treatment wetlands could be significantly increased by addition of surfaces such as twigs.     

Atmospheric quality and distribution of heavy metals in Argentina employing Tillandsia capillaris as a biomonitor

The atmospheric quality and distribution of heavy metals were evaluated throughout a wide region of Argentina. In addition, the biomonitor performance of Tillandsia capillaris Ruiz & Pav. f. capillaris was studied in relation to the accumulation of heavy metals and to its physiologic response to air pollutants. A sampling area of 50,000 km2 was selected in the central region of the Argentine Republic. This area was subdivided into grids of 25 x 25 km. Pools of T. capillaris, where present, were collected at each intersection point. From each pool three sub-samples were analyzed independently. Furthermore, five replicates were collected at 20% of the points in order to analyze the variability within the site. The content of Co, Cu, Fe, Ni, Mn, Pb and Zn was determined by Atomic Absorption Spectrometry. Chemical-physiological parameters were also determined to detect symptoms of foliar damage. Chlorophylls, phaeophytins, hydroperoxy conjugated dienes, malondialdehyde and sulfur were quantified in T. capillaris. Some of these parameters were used to calculate a foliar damage index. Data sets were evaluated by one-way ANOVA, correlation analysis, principal component analysis and mapping. Geographical distribution patterns were obtained for the different metals reflecting the contribution of natural and anthropogenic emission sources. According to our results it can be inferred that Fe, Mn and Co probably originated in the soil. For Pb, the highest values were found in the mountainous area, which can be attributed to the presence of Pb in the granitic rocks. Ni showed mainly an anthropogenic origin, with higher values found in places next to industrial centers. For Zn the highest values were in areas of agricultural development. The same was observed for Cu, whose presence could be related to the employment of pesticides. The foliar damage index distribution map showed that the central and southeastern zones were the ones where the major damage in the bioindicator was found. The central zone coincides with the city of Córdoba whereas the southeastern area is strictly agricultural, so the high values found there could be related to the use of pesticides.     

Source extraction information from air quality data monitored in an Argentinean steel mill

A statistical analysis of a series of ambient air concentrations of suspended particulate matter (SPM) and NO2 is presented. Measurements were taken at four sites that belong to an Argentinean steel mill and in another site located in its vicinity. The air pollutants were measured during a three-week exploratory sampling. The monitoring sites were selected on the basis of relevant characteristics of the emission sources and the corresponding climatological statistics of the last decade. Suspended particulate matter with aerodynamic diameter of less than 10 microm (PM10) and NO2 were continuously measured at only one site, while 1-hr samples of NO2 and 24-hr samples of total SPM and SO2 were collected at the other sites. The registered concentrations show that SPM was the pollutant of major concern. A first estimate about the nature of the contribution of the different sources of particles and NO2 present in the area was obtained through the statistical analysis of measured concentration data coupled with prevalent meteorological variables.     

Exploring the energy-environment growth nexus in francophone Africa in presence of institutions

Environment, Development and Sustainability - This paper analyses the role of renewable energy, ecological footprint and institutions on economic growth (measured by per capita GDP) in Francophone...     

An analysis of university sustainability reports from the GRI database: an examination of influential variables

In the business context, many papers have examined whether certain variables can affect sustainability disclosure practices. However, research on universities has mainly been addressed to explore the extent of sustainability information reported with little focus on determining the factors that may affect it. This paper analyzes the influence exerted by some variables concerning the extent of information reported in the university sustainability reports included in this study. To accomplish this task, data were collected using a content analysis of the university sustainability reports extracted from the GRI sustainability disclosure database. The findings reveal that sustainability disclosure practices by universities are explained by different factors, among which are institutionalization, geographical region, external assurance and leadership. Such results are supported jointly by the underpinnings of the institutional and legitimacy theories in response to coercive and mimetic pressures and by the need to improve reputation in society.     

Assessment of ambient air quality in Eskişehir, Turkey

This paper presents an assessment of air quality of the city Eski?ehir, located 230 km southwest to the capital of Turkey. Only five of the major air pollutants, most studied worldwide and available for the region, were considered for the assessment. Available sulphur dioxide (SO(2)), particulate matter (PM), nitrogen dioxide (NO(2)), ozone (O(3)), and non-methane volatile organic carbons (NMVOCs) data from local emission inventory studies provided relative source contributions of the selected pollutants to the region. The contributions of these typical pollution parameters, selected for characterizing such an urban atmosphere, were compared with the data established for other cities in the nation and world countries. Additionally, regional ambient SO(2) and PM concentrations, determined by semi-automatic monitoring at two sites, were gathered from the National Ambient Air Monitoring Network (NAAMN). Regional data for ambient NO(2) (as a precursor of ozone as VOCs) and ozone concentrations, through the application of the passive sampling method, were provided by the still ongoing local air quality monitoring studies conducted at six different sites, as representatives of either the traffic-dense-, or coal/natural gas burning residential-, or industrial/rural-localities of the city. Passively sampled ozone data at a single rural site were also verified with the data from a continuous automatic ozone monitoring system located at that site. Effects of variations in seasonal-activities, newly established railway system, and switching to natural gas usage on the temporal changes of air quality were all considered for the assessment. Based on the comparisons with the national [AQCR (Air Quality Control Regulation). Ministry of Environment (MOE), Ankara. Official Newspaper 19269; 1986.] and a number of international [WHO (World Health Organization). Guidelines for Air Quality. Geneva; 2000. Downloaded in January 2006, website: http://www.who.int/peh/; EU (European Union). Council Directive 1999/30/EC relating to limit values for sulfur dioxide, nitrogen dioxide and lead in ambient air. Of J Eur Communities L 163: 14-30; 29.6.1999; EU (European Union). Council Directive 2002/3/EC relating to ozone in ambient air. Of J Eur Communities. L 67: 14-30; 9.3.2002.; USEPA (U.S. Environmental Protection Agency). National Ambient Air Quality Standards (NAAQS). Downloaded in January 2006, website: http://www.epa.gov/ttn/naaqs/] ambient air standards, among all the pollutants studied, only the annual average SO(2) concentration was found to exceed one specific limit value (EU limit for protection of the ecosystem). A part of the data (VOC/NO(x) ratio), for determining the effects of photochemical interactions, indicated that VOC-limited regime was prevailing throughout the city.     

How ants determine the number of potential recruits

In this paper we present a model that determines the number of potential recruits of Lasius niger, when feeding on a liquid sugar source. The core of the model are two rules: (i) there is a number of workers (facultative foragers) that become potential recruits if starved and (ii) facultative foragers are more likely to become starved than nonforagers because they are more likely to donate food in a trophallaxis (sugar-exchange) event. We develop and explore an analytical model based on these rules, deriving the number of potential recruits after an arbitrary period of starvation. We develop a simplified recruitment model and observe that the predictions of the model are in rough agreement with the empirical data.     

Histochemical and ultrastructural characterisation of mantle storage cells in the hydrothermal-vent bivalve Bathymodiolus azoricus

This study reports on two types of storage cells that are present in the mantle connective tissue of the deep-sea mussel Bathymodiolus azoricus. One type corresponds to the adipogranular cells, a kind of storage cell previously described in other bivalves. In these cells extensive regions of the cytoplasm are filled with glycogen deposits and these zones became strongly stained after histochemical (PAS) or ultrastructural detection of polysaccharides. Several lipid droplets and membrane bound granules containing homogeneous electron-dense material are also present in adipogranular cells. A second type of cell contains large lysosomes in addition to numerous lipid droplets, but lacking cytoplasmic glycogen deposits. Due to these characteristics we named them adipolysosomal cells. They can be identified in semi-thin sections stained with PAS reaction because the lysosomes are the only positively stained structures. In the connective tissue of the mantle, some cells containing many lysosomes and a few lipid droplets were also observed. These cells differ from the adipolysosomal cells mainly because they have a reduced amount of lipid reserves, and could be an initial stage in the development of adipolysosomal cells. The vesicular connective tissue cells that in other Mytilidae are specialised in glycogen storage were not detected in B. azoricus. The reserves accumulated in the two types of storage cells described in B. azoricus may be important for the survival of these hydrothermal-vent bivalves if their nutrition is affected by a temporary loss or reduction of endosymbiotic bacteria due to sulphide and/or methane shortage caused by oscillations in vent activity.     

Mechanosensory properties of the mouthpart setae of the European shore crab <Emphasis Type="Italic">Carcinus maenas</Emphasis>

In decapod crustaceans, the largest density and diversity of sensilla, referred to as setae, is in general found on the mouthparts, but little is known about their sensory properties and thereby their functions. Here data are presented from mechanoreceptors from the two largest mouthparts, maxilliped 2 and 3, of the European shore crab Carcinus maenas. The mechanoreceptors were found to respond to either displacements of the entire seta or bending of the setal shaft. The displacement-sensitive cells encode both the amplitude and the velocity of the displacement and about half were found to be directional but most in a non-exclusive way. The amplitude of the stimulus is encoded in the number of spikes produced with a linear correlation. The velocity is encoded in the interspike intervals with shorter intervals at higher velocities. In the latter case, the correlation follows a power function. The physiological data is correlated with the morphology and usage of the maxillipeds were examined with scanning electron microscopy and macro video recordings respectively. Recordings were obtained from cells associated with four different setal types and they all showed similar mechanosensory properties supporting that the external morphology of setae is more closely connected to their non-sensory functions, e.g., mechanical manipulation of the food items. The details of the sensory properties together with the high setal density, especially on maxilliped 3, suggest that a large amount of tactile information is gathered during feeding.