The variability and intrinsic remediation of a BTEX plume in anaerobic sulphate-rich groundwater

Data from long-term groundwater sampling, limited coring, and associated studies are synthesised to assess the variability and intrinsic remediation/natural attenuation of a dissolved hydrocarbon plume in sulphate-rich anaerobic groundwater. Fine vertical scale (0.25- and 0.5-m depth intervals) and horizontal plume-scale (>400 m) characteristics of the plume were mapped over a 5-year period from 1991 to 1996. The plume of dissolved BTEX (benzene, toluene, ethylbenzene, xylene) and other organic compounds originated from leakage of gasoline from a subsurface fuel storage tank. The plume was up to 420 m long, less than 50 m wide and 3 m thick. In the first few years of monitoring, BTEX concentrations near the point of leakage were in approximate equilibrium with non-aqueous phase liquid (NAPL) gasoline. NAPL composition of core material and long-term trends in ratios of BTEX concentrations in groundwater indicated significant depletion (water washing, volatilisation and possibly biodegradation) of benzene from residual NAPL after 1992. Large fluctuations in BTEX concentrations in individual boreholes were shown to be largely attributable to seasonal groundwater flow variations. A combination of temporal and spatial groundwater quality data was required to adequately assess the stationarity of plumes, so as to allow inference of intrinsic remediation. Contoured concentration data for the period 1991 to 1996 indicated that plumes of toluene and o-xylene were, at best, only partially steady state (pseudo-steady state) due to seasonal groundwater flow changes. From this analysis, it was inferred that significant remediation by natural biodegradation was occurring for BTEX component plumes such as toluene and o-xylene, but provided no conclusive evidence of benzene biodegradation. Issues associated with field quantification of intrinsic remediation from groundwater sampling are highlighted. Preferential intrinsic biodegradation of selected organic compounds within the BTEX plume was shown to be occurring, in parallel with sulphate reduction and bicarbonate production. Ratios of average hydrocarbon concentrations to benzene for the period 1991 to 1992 were used to estimate degradation rates (half-lives) at various distances along the plume. The estimates varied with distance, the narrowest range being, for toluene, 110 to 260 days. These estimates were comparable to rates determined previously from an in situ tracer test and from plume-scale modelling.     

The rise of risk and the decline of politics

This paper argues that the rise of risk and formal risk assessment has contributed to the demise of representative democratic politics by displacing public discourses about values with technical justifications for decision making. Furthermore, risk plays a central role in the displacement of governmental responsibility to private sector and NGO actors at the same time as facilitating government control over citizens—the Janus faces¹ of governance and governmentality. Arguing that the turn to public participation cannot be the panacea for the present situation, the paper concludes by calling for revitalisation of representative institutions, the development of real-time technology assessment and development of popular connoisseurship of science and technology.     

A Rapid Titrimetric Method for Sulfate in Lead Dioxide Exposed to Atmospheric Sulfur Pollution

A titrimetric method is described for the analysis of sulfate in lead dioxide candles which have been exposed to atmospheric sulfur pollution. The time taken to analyse one sample is 3 hr. Sixty milliliters of 8% ammonium carbonate solution is used to convert the lead sulfate present on the candle to ammonium sulfate. The solution is filtered lc remove lead dioxide, and an aliquot of the filtrate is heated to remove ammonium carbonate. The solution of ammonium sulfate remaining is titrated directly for sulfate with 0.02 M barium perchlorate, using Thoron as indicator. The accuracy of the method is ±10 and ±6 % of theoretical, for 10 mg, and 40 mg or greater amounts of sulfate, respectively. For 2 mg of sulfate, results are about 20% high. Good agreement has been obtained between results for duplicate field candles, analyzed by the standard sodium carbonate gravimetric method, and the method presented, over a five-month period.     

The rise of risk and the decline of politics

This paper argues that the rise of risk and formal risk assessment has contributed to the demise of representative democratic politics by displacing public discourses about values with technical justifications for decision making. Furthermore, risk plays a central role in the displacement of governmental responsibility to private sector and NGO actors at the same time as facilitating government control over citizens—the Janus faces¹ of governance and governmentality. Arguing that the turn to public participation cannot be the panacea for the present situation, the paper concludes by calling for revitalisation of representative institutions, the development of real-time technology assessment and development of popular connoisseurship of science and technology.     

Foraging behavior and echolocation of wild horseshoe bats Rhinolophus ferrumequinum and R. hipposideros (Chiroptera,Rhinolophidae)

Summary 1. Echolocation and foraging behavior of the horseshoe bats Rhinolophus ferrumequinum and R. hipposideros feeding under natural conditions are described. 2. The calls of both species consisted predominantly of a long CF segment, often initiated and terminated by brief FM sweeps of substantial bandwidth. 3. R. hipposideros typically flew close to vegetation, and fed by aerial hawking, gleaning and by pouncing on prey close to the ground. R. hipposideros called with a CF segment close to 112 kHz which is the second harmonic of the vocalization; its calls included low intensity primary harmonics, and had prominent initial and terminal FM sweeps of considerable bandwidth. When searching for prey on the wing it had longer interpulse intervals than R. ferrumequinum, but emitted shorter pulses at a higher repetition rate; overall it had a similar duty cycle to R. ferrumequinum. 4. R. ferrumequinum, calling with a CF segment close to 83 kHz, also used harmonics other than the dominant secondary in its calls, and modified its echolocation according to ecological conditions. This species showed certain parallels with R. rouxi of Asia. It was observed feeding by aerial hawking and by flycatching. When scanning for prey from a perch (perch hunting), calls were of shorter duration, and interpulse intervals were on average longer, than when bats were flying. Mean duty cycle was longer in flight, and the bandwidths and frequency sweep rates of the FM segments in the calls increased in comparison with perched bats. 5. FM information may facilitate determination of target range and the location and nature of obstacles; it may also be involved in the interpretation of echoes and the detection of moving targets among clutter. The rising FM sweep initiating the call in both species when flying (and to a lesser extent perch hunting) in the wild must have a significant adaptive role, and should be considered an essential component of the call; rhinolophids should be termed FM/CF/FM bats.Abbreviations CF constant frequency - FM frequency modulated - FM₁ initial rising frequency sweep - FM₂ terminal falling frequency sweep - PRR pulse repetition rate - SD standard deviation - SNR signal-to-noise ratio     

Central place foraging by breeding Cook’s petrel Pterodroma cookii: foraging duration reflects range, diet and chick meal mass

Pelagic seabirds are central place foragers during breeding and variation in foraging trip duration and range reflect differences in diet and chick provisioning, through the exploitation of divergent habitats of varying productivity. We tested whether these relationships hold in small procellarriids by equipping chick-rearing Cook’s petrel Pterodroma cookii (200 g) with geolocation-immersion loggers, conducting isotope analysis of blood and measuring chick meal mass following foraging trips of varying duration. Cook’s petrel tracked during chick rearing from Little Barrier Island (LBI) and Codfish Island (CDF), New Zealand had larger maximum ranges during longer foraging trips. Blood nitrogen isotope signatures (δ¹⁵N) of adults were significantly higher after foraging trips of longer duration, but not of greater maximum range. There was no significant relationship between blood carbon isotope signatures (δ¹³C) and foraging trip characteristics. Proportion of time spent on the sea surface and the mass of the meal brought back to chicks were consistently greater for Cook’s petrel with larger maximum ranges, which in the case of birds from CDF coincided with productive subtropical convergence zone habitats. As predicted, trip duration reflected divergent foraging behaviours in Cook’s petrel during breeding. We suggest that the availability of different prey is a key factor governing at-sea distributions and dietary composition of this species.     

Alberta's oil sands reclamation policy trajectory: the role of tense layering,policy stretching,and policy patching in long-term policy dynamics

As the Canadian oil sands development matures, an increasingly important policy activity is reclamation. Reclamation has received limited attention compared with the broader discussion of oil sands expansion, however, and its past direction and future trajectory are unclear. Recent moves to reform the policy in Alberta have been interpreted simultaneously as a major change and a marginal adaptation to the existing framework. This article employs a historical-institutional perspective to help reconcile this debate and further understanding of changes to Alberta's oil sands reclamation policies over the past half century. It traces the factors and outlines the processes which have driven its evolution since 1963 with special attention paid to the 2011 Oil Sands Progressive Reclamation Strategy, the most recent attempt to reform oil sands reclamation policy. The article reveals a complex long-term pattern of policy development in which processes of ‘tense layering’ of new initiatives on top of old elements resulted in a constantly shifting policy landscape as existing policy instruments and settings were ‘stretched’ to cover new circumstances but failed to resolve tensions between successive policy layers. After 1993, however, a more reflective process was put into place in which policy feedback informed alterations intended to reduce or remove tensions between successive layers. Such a policy ‘patching’ process is shown to have helped resolve tensions associated with earlier stretching of the existing regime and adds to the vocabulary of more general studies of policy dynamics.     

Bioacoustic distances between the begging calls of brood parasites and their host species: a comparison of metrics and techniques

A variety of bioacoustics distance metrics have been used to assess similarities in the vocalizations of different individuals. Here, we provide a detailed analysis of several acoustic similarity indices, some of which have been developed with the specific aim of characterizing the sensory coding of auditory stimuli. We compare different approaches through the analysis of begging calls of several passerine species and specialist brood parasitic cuckoos that putatively evolved to mimic their hosts. The different bioacoustics distances did not provide consistently correlated similarity patterns, implying that they are sensitive to different sound features. However, the encoded spectrogram alignment method was correlated with all other acoustic distance metrics, suggesting that this method provides a consistent approach to use when the perceptually salient sound parameters are unknown for a particular species. Our analyses confirm that statistical similarity of begging calls can be detected in a New Zealand pair of host and specialist parasite species. We also show detectable similarity in two other Australasian host–parasite pairs and another New Zealand system, but to a more limited extent. By examining phylogenetic patterns in the begging call diversity, we also confirm that specialist cuckoos have evolved to mimic the begging calls of their hosts but host species have not co-evolved to modify their calls in response to begging call similarity by the parasite. Our results illustrate that understanding the function and mechanism of behavioral copying and mimicry requires statistically consistent measures of similarity that are related to both the physical aspects of the particular display and the sensory basis of its perception.