Potential for natural and enhanced attenuation of sulphanilamide in a contaminated chalk aquifer

Understanding antibiotic biodegradation is important to the appreciation of their fate and removal from the environment. In this research an Isotope Ratio Mass Spectrometry(IRMS)method was developed to evaluate the extent of biodegradation of the antibiotic,sulphanilamide, in contaminated groundwater. Results indicted an enrichment in δ~(13)C of8.44‰ from-26.56(at the contaminant source) to-18.12‰(300 m downfield of the source).These results confirm reductions in sulphanilamide concentrations(from 650 to 10 mg/L)across the contaminant plume to be attributable to biodegradation(56%) vs. other natural attenuation processes, such as dilution or dispersion(42%). To understand the controls on sulphanilamide degradation ex-situ microcosms assessed the influence of sulphanilamide concentration, redox conditions and an alternative carbon source. Results indicated, high levels of anaerobic capacity(~50% mineralisation) to degrade sulphanilamide under high(263 mg/L), moderate(10 mg/L) and low(0.02 mg/L) substrate concentrations. The addition of electron acceptors; nitrate and sulphate, did not significantly enhance the capacity of the groundwater to anaerobically biodegrade sulphanilamide. Interestingly, where alternative carbon sources were present, the addition of nitrate and sulphate inhibited sulphanilamide biodegradation. These results suggest, under in-situ conditions, when a preferential carbon source was available for biodegradation, sulphanilamide could be acting as a nitrogen and/or sulphur source. These findings are important as they highlight sulphanilamide being used as a carbon and a putative nitrogen and sulphur source, under prevailing iron reducing conditions.     

The Hyper-Envelope Modeling Interface (HEMI): A Novel Approach Illustrated Through Predicting Tamarisk (Tamarix spp.) Habitat in the Western USA

Habitat suitability maps are commonly created by modeling a species’ environmental niche from occurrences and environmental characteristics. Here, we introduce the hyper-envelope modeling interface (HEMI), providing a new method for creating habitat suitability models using Bezier surfaces to model a species niche in environmental space. HEMI allows modeled surfaces to be visualized and edited in environmental space based on expert knowledge and does not require absence points for model development. The modeled surfaces require relatively few parameters compared to similar modeling approaches and may produce models that better match ecological niche theory. As a case study, we modeled the invasive species tamarisk (Tamarix spp.) in the western USA. We compare results from HEMI with those from existing similar modeling approaches (including BioClim, BioMapper, and Maxent). We used synthetic surfaces to create visualizations of the various models in environmental space and used modified area under the curve (AUC) statistic and akaike information criterion (AIC) as measures of model performance. We show that HEMI produced slightly better AUC values, except for Maxent and better AIC values overall. HEMI created a model with only ten parameters while Maxent produced a model with over 100 and BioClim used only eight. Additionally, HEMI allowed visualization and editing of the model in environmental space to develop alternative potential habitat scenarios. The use of Bezier surfaces can provide simple models that match our expectations of biological niche models and, at least in some cases, out-perform more complex approaches.     

Use of principal components analysis (PCA) on estuarine sediment datasets: The effect of data pre-treatment

Principal components analysis (PCA) is a multivariate statistical technique capable of discerning patterns in large environmental datasets. Although widely used, there is disparity in the literature with respect to data pre-treatment prior to PCA. This research examines the influence of commonly reported data pre-treatment methods on PCA outputs, and hence data interpretation, using a typical environmental dataset comprising sediment geochemical data from an estuary in SE England. This study demonstrated that applying the routinely used log (x + 1) transformation skewed the data and masked important trends. Removing outlying samples and correcting for the influence of grain size had the most significant effect on PCA outputs and data interpretation. Reducing the influence of grain size using granulometric normalisation meant that other factors affecting metal variability, including mineralogy, anthropogenic sources and distance along the salinity transect could be identified and interpreted more clearly.     

An unintended experiment in fisheries science: a marine area protected by war results in Mexican waves in fish numbers-at-age

Marine protected areas (MPAs) are attaining increasing importance in the management of marine ecosystems. They are effective for conservation in tropical and subtropical areas (mainly coral and rocky reefs), but it is debated whether they are useful in the management of migratory fish stocks in open temperate regions. World War II created a large marine area within which commercial fishing was prevented for 6 years. Here we analyse scientific trawl data for three important North Sea gadoids, collected between 1928 and 1958. Using statistical models to summarise the data, we demonstrate the potential of MPAs for expediting the recovery of over-exploited fisheries in open temperate regions. Our age-structured data and population models suggest that wild fish stocks will respond rapidly and positively to reductions in harvesting rates and that the numbers of older fish in a population will react before, and in much greater proportion, than their younger counterparts in a kind of Mexican wave. Our analyses demonstrate both the overall increase in survival due to the lack of harvesting in the War and the form of the age-dependent wave in numbers. We conclude that large closed areas can be very useful in the conservation of migratory species from temperate areas and that older fish benefit fastest and in greater proportion. Importantly, any rise in spawning stock biomass may also not immediately result in better recruitment, which can respond more slowly and hence take longer to contribute to higher future harvestable biomass levels.     

Can Extractive Reserves Save the Rain Forest? An Ecological and Socioeconomic Comparison of Nontimber Forest Product Extraction Systems in Petén,Guatemala, and West Kalimantan,Indonesia

We compare existing nontimber forest product extraction systems in Petén, Guatemala, and West Kalimantan, Indonesia, to identify key ecological, socioeconomic, and political factors in the design and implementation of extractive reserves. Ecological parameters include the spatial and temporal availability of harvested products and the sustainability of harvesting practices from both a population and an ecosystem perspective. Socioeconomic and political factors include the presence or absence of well-defined resource tenure rights, physical and social infrastructure, markets, and alternative land uses. We conclude that although extractive reserves can play a significant role in preserving tropical forests as a part of a broader land-use spectrum, their effectiveness is highly dependent on prevailing local ecological, socioeconomic, and political conditions. Ultimately, extractive reserves should be regarded as one component of an overall approach to the problem of tropical deforestation.     

The firm,environmental management and environmental measures: Lessons from a survey of European manufacturing firms

This paper reports on the results of a survey of environmental management and technical measures amongst almost 2000 European firms. Logit analysis is undertaken to determine the effects of firm characteristics, commercial conditions, perceived environmental impacts, expected benefits and stakeholder pressures on the probability of having an environmental management system in place. Subsequently, determinants of the likelihood of undertaking environmental actions in five environmental areas are estimated. There is a positive effect of environmental management on the likelihood of undertaking technical measures to reduce environmental impacts in some (but not all) areas, as well as a positive role for integrated environmental management strategies.     

A simple method for preparing prometaphase chromosomes from amniotic fluid cell cultures

A simple method for preparing prometaphase chromosomes from amniotic fluid cell cultures is described. The technique is based upon several key steps including: (1) reduced colcemid concentration, (2) reduced exposure to trypsin-EDTA, and (3) maintaining cells in single suspension by adjusting cell concentration appropriately. Chromosomes with banding resolution up ot 800 bands per haploid set can be routinely produced. The described methodology is particularly useful in defining and establishing the clinical significance of subtle structural aberrations.