A methodology to estimate the denitrifying capacity of a riparian wetland

Numerous studies have shown that riparian wetlands can play an important role in reducing nitrate concentrations before the ground water discharges into streams. Denitrification has been identified as an important process for this removal. Several approaches have been proposed to predict the denitrifying removal capacity of a riparian wetland, but no widely used tool exists to precisely quantify this capacity at the landscape scale. We propose such a methodology based on modeling the spatial variation of soil-water interactions in the entire riparian wetland. Mean values of denitrification enzyme activity (DEA) within three soil-denitrifying classes were 604, 212, and 24 ng N g(-1) h(-1) for Classes 3, 2, and 1, respectively. The study area, having a ground surface of about 15000 m2, was underlain by an aquifer with a calculated volume of 60000 m3, less than 10000 m3 of which corresponded to active denitrifying horizons (Classes 2 and 3). By volume, approximately 30% of Class 3 and 70% of Class 2 were interacting with ground water. The denitrifying removal capacity of our wetland was calculated to be about 1.8 kg N m(-2) yr(-1). The calculated denitrifying capacity of our site was less than expected. This is due to the fact that not all ground water interacts with the horizons having the highest denitrifying capacity. Thus, we show that whatever the system is, specific local pedological and hydrogeological conditions and their interactions are paramount in controlling the denitrification process.     

Fetal blood group studies during mid-trimester pregnancy and the management of severe isoimmunization

Fetal blood samples collected at 14–22 weeks' gestation by fetoscopy have been analysed for 25 different red cell antigens and anti-A antibodies. The results obtained demonstrate that the technique can be used to determine fetal blood groups during mid-pregnancy and also to provide the opportunity to study the physiological and pathological developments of blood groups and their antibodies and to manage more rationally those pregnancies threatened by erythroblastosis fetalis.     

Water-soluble fractions of composts for the photodegradation of organic pollutants in solar light

Composts fractions were extracted by water from composts at the beginning and at the end of the composting process. These water extracts were characterized by elementary analysis and spectroscopies, and then, tested for their capacity to photosensitize the degradation of three aromatic compounds: Irgarol, fenuron, and 2,4,6-trimethylphenol. In solar light, the water extracts (25 mg/l) were found to completely degrade 2,4,6-trimethylphenol after 24 h, and afford a transformation of fenuron and Irgarol of 25% and 18%, respectively.An erratum to this article can be found at     

Assessment of municipal waste compost as a daily cover material for odour control at landfill sites

The ability of municipal waste compost as a daily cover material to reduce the odorous emissions associated with landfill surfaces was investigated. Trials were carried out using landfill gas, a certified sulphurous gas mix and ambient air as a control. Odorous gas was passed through portable test column filled with compost at different densities (590 kg/m3 and 740 kg/m3). Gas samples were taken from the inlet, outlet and at varying column depths and examined using a combination of sensory analysis (olfactometry) and a novel analytical method (Transportable Selected Ion Flow Tube--TSIFT). Results for the trials using landfill gas showed a 69% odour reduction (OU/m3) through the column for compost with a bulk density of 590 kg/m3, and a reduction of 97% using compost with a bulk density of 740 kg/m3. TSIFT analysis showed an overall decrease in the concentration of terpenes, and sulphurous compounds in the outlet gas from the column for both bulk densities. No significant trend could be identified for the concentrations at different depths within the column. Results show the ability of compost to reduce landfill odours under differing conditions. The inconclusive data provided by TSIFT analysis may be due to the analysis of compounds that are not contributing to odour, and thus highlights the potential for synergetic effects and the importance of sensory measurement when examining odorous emissions.     

Ozone in Central England: the impact of 20 years of precursor emission controls in Europe

Episodic peak ozone levels over the 1990–2007 period appear to have declined strongly whilst annual mean daily maximum levels have risen over the same period at monitoring sites within the midlands regions of the UK. Sensitivity studies carried out with a photochemical trajectory model have shown that European policies to control Volatile Organic Compound (VOC) and Nitrogen Oxides (NO_x) emissions are the likely cause of the decline in episodic peak levels. There appeared to have been little influence on the episodic peak from changes in intercontinental trans-Atlantic transport but an overwhelming influence on the annual mean daily maximum levels. Non-linear relationships between VOC and NO_x emission controls and ozone, together with the ambition level set by policy-makers, appear to explain why ozone levels in Central England still do not meet internationally accepted air quality guidelines despite two decades of policy actions within Europe.     

Measuring and modeling the seasonal changes of an urban Green Treefrog (Hyla cinerea) population

Green Treefrogs (Hyla cinerea) were captured, marked, measured and released at an urban study site in Lafayette, LA, during the 2004 and 2005 breeding seasons. A statistical method based on a generalization of the hypergeometric distribution was used to derive weekly time-series estimates of the population sizes. To describe the population dynamics, a stage structured mathematical model was developed and compared to time-series obtained from the weekly population estimates study using a least-squares approach. Two fitting experiments were done: (1) Using uniform distribution for the birth rate during the breeding season; (2) Using a birth rate distributed according to weekly data on frog calling intensity. Although both model-to-data fits look very promising during the years 2004 and 2005 and result in similar inherent survivorship rates for the tadpoles, juvenile and adult frogs, the fit that uses the calling data predicts a lower number of tadpoles and frogs in the long term than the one that uses uniform birth distribution. The parameter estimates resulting from these fitting experiments are used in the context of stochastic simulations to derive extinction and persistence probabilities for this population. Due to the oscillatory dynamics (with high amplitude) evidenced by the capture-recapture data and corroborated by the model, it is suggested that anuran monitoring efforts should take into account the natural intra-annual variation in population size.     

Genetic structure across the GBR: evidence from short-lived gobies

The Great Barrier Reef (GBR) exhibits distinct cross-shelf zonation. These patterns are particularly well documented in reef fishes and have been attributed to either environmental gradients (e.g. wave energy, oceanography) or barriers to gene flow. This study examined the extent to which barriers to gene flow contribute to cross-shelf patterns by examining the mitochondrial DNA of gobies (genus Eviota). The genus Eviota was selected due to its extreme life history characteristics (shortest vertebrate lifespan) and cross-shelf distribution patterns (E. queenslandica, inner- and mid-shelf, and E. albolineata mid- and outer-shelf). Although cross-shelf barriers to gene flow were predicted, this study found no population structure between shelf locations. However, a genetically distinct population of E. queenslandica (the inner-shelf species) was observed at North Direction Island (Phi_st = 0.088, P = 0.004). As no comparable structure was observed in E. albolineata (the outer-shelf species) it may be that habitat type (E. queenslandica = reef lagoon, E. albolineata = reef crest) is a significant factor driving the structure observed in E. queenslandica. Larval behaviour, olfactory or auditory senses and reef selection at settlement could be assisting larvae to return to reefs similar to natal reefs. We suggest that ecological gradients are more important than barriers to gene flow in structuring cross-shelf distributions within Eviota.     

Helium isotopic constraints on simulated ocean circulations: implications for abyssal theories

There is ongoing controversy as to the dynamical significance of geothermal heat flow in shaping the abyssal circulation. In this paper, we gauge the impact of geothermal heating and vertical mixing parameterizations in the general circulation model OPA. The experiments are evaluated by comparing simulated mantle ³He with observations collected during the GEOSECS and WOCE programs. This tracer is particularly adapted to the validation of our numerical simulations because its injection into the ocean interior is tightly linked to geothermal processes. In agreement with previous studies, the model circulation is found very sensitive to the parameterization of the vertical mixing. The meridional overturning circulation (MOC) is globally intensified when moving from a constant mixing to a version with enhanced mixing near the ocean bottom, with the most drastic variation observed for AABW (+ 50%). Adding the geothermal heat flux mainly affects AABW circulation in the model, enhancing it all the more as the meridional circulation is slow (low vertical mixing), but proportionally less so when it is more vigorous (enhanced vertical mixing). This can be understood from the requirement of the abyssal ocean to maintain heat balance. The evaluation with mantle ³He simulations reveals that the version with low vertical mixing, with its sluggish circulation, produces unrealistically high a ³He isotopic composition. However, with a vertical mixing that is enhanced at depth, the ³He distribution falls within an acceptable range of values in the deep ocean. Finally, adding the geothermal heating to this enhanced mixing case provides a substantial improvement of the simulation of AABW in all basins but the Indian Ocean. ³He isotopic composition is then in good agreement with the observations. Taken jointly with observational estimates of the MOC intensity, these independent isotopic constraints suggest that both geothermal heating and enhanced diapycnal mixing at depth are key ingredients in the realistic simulation of abyssal circulation.     

Protected area downgrading,downsizing, and degazettement as a threat to iconic protected areas

Protected areas (PAs) are expected to conserve nature and provide ecosystem services in perpetuity, yet widespread protected area downgrading, downsizing, and degazettement (PADDD) may compromise these objectives. Even iconic protected areas are vulnerable to PADDD, although these PADDD events are often unrecognized. We identified 23 enacted and proposed PADDD events within World Natural Heritage Sites and examined the history, context, and consequences of PADDD events in 4 iconic PAs (Yosemite National Park, Arabian Oryx Sanctuary, Yasuní National Park, and Virunga National Park). Based on insights from published research and international workshops, these 4 cases revealed the diverse pressures brought on by competing interests to develop or exploit natural landscapes and the variety of mechanisms that enables PADDD. Knowledge gaps exist in understanding of the conditions through which development pressures translate to PADDD events and their impacts, partially due to a lack of comprehensive PADDD records. Future research priorities should include comprehensive regional and country-level profiles and analysis of risks, impacts, and contextual factors related to PADDD. Policy options to better govern PADDD include improving tracking and reporting of PADDD events, establishing transparent PADDD policy processes, coordinating among legal frameworks, and mitigating negative impacts of PADDD. To support PADDD research and policy reforms, enhanced human and financial capacities are needed to train local researchers and to host publicly accessible data. As the conservation community considers the achievements of Aichi Target 11 and moves toward new biodiversity targets beyond 2020, researchers, practitioners, and policy makers need to work together to better track, assess, and govern PADDD globally.