Metabolic disposition of lactate in the horseshoe crab Limulus polyphemus and the stone crab Menippe mercenaria

The metabolism of ¹⁴C-labelled lactate was investigated in the horseshoe crab Limulus polyphemus and the stone crab Menippe mercenaria. When a bolus of (¹⁴C-U)-D-lactate was injected into L. polyphemus, there was substantial release pf ¹⁴CO₂ into the medium. In the case of M. mercenaria, ¹⁴CO₂ release was also observed after injection of (¹⁴C-U)-L-lactate into experimental individuals. Analysis of the distribution of radioactivity in whole body extracts of both species revealed easily detectable amounts of radioactivity in the glycogen fraction, although the bulk of the radioactivity was in the cation, anion/neutral and CO₂ fractions. To investigate the metabolism of lactate further, ¹⁴C-labelled lactate was injected into large individuals of L. polyphemus and M. mercenaria, and the distribution of radioactivity was determined in the hemolymph, muscle and hepatopancreas. Utilization of (¹⁴C-U)-D-lactate by L. polyphemus resulted in the accumulation of significant amounts of labelled glucose in all three body compartments as well as the production of labelled glycogen in the telson levator muscle and hepatopancreas. Utilization of (¹⁴C-U)-L-lactate resulted in a similar pattern of glucose and glycogen labelling in the hemolymph, cheliped muscle and hepatopancreas of M. mercenaria. These studies demonstrate that both L. polyphemus and M. mercenaria have the capacity for glyco- and gluconeogenesis using lactate as the substrate.     

Feeding strategies and diets of breeding grey-headed and wandering albatrosses at South Georgia

The foraging areas and diets of the grey-headed albatross Thalassarche chrysostoma and wandering albatross Diomedea exulans were studied in March/April 2000 at Bird Island, South Georgia, during their respective chick-rearing and brood-guard periods. Oceanographically, March/April 2000 was abnormal, with warm conditions close to South Georgia. These conditions affected albatross foraging behaviour, particularly that of grey-headed albatrosses. Both species tended to forage in different areas of the ocean, with significant differences in trip durations. Grey-headed albatrosses (n=9) foraged mainly in Antarctic waters (predominantly shelf waters of the South Shetland Islands and Antarctic Peninsula, and also in oceanic waters around South Georgia), feeding mainly on krill (Euphausia superba; 77% by mass). Foraging trips lasted 13.3 days (range: 5–26 days), far longer than the 1–3 days found in previous studies. Only one grey-headed albatross was associated with the APF (Antarctic Polar Front), a reported foraging area in recent studies. Wandering albatrosses (n=9) foraged in Antarctic (South Georgia Shelf) and Antarctic Polar Frontal Zone (APFZ) waters, with trips of 1–4 days trip duration (usual for this species), feeding on fish (46% by mass) and cephalopods (32%). One bird was associated with the APF, and two birds foraged on the shelf/shelf break over the Patagonian shelf. These findings suggest that sea surface temperature anomalies, produced by movement of the APF closer to South Georgia or by eddies, may have had an effect on the foraging strategy of grey-headed albatrosses that year (the main prey of grey-headed albatrosses in previous studies, the ommastrephid Martialia hyadesi, is known to be associated with the APF). Also, when both albatross breeding periods overlap, their foraging areas were complementary, which reflected the prey taken.     

Independent effects of fragmentation on forest songbirds: an organism-based approach.

The degree to which spatial patterns influence the dynamics and distribution of populations is a central question in ecology. This question is even more pressing in the context of rapid habitat loss and fragmentation, which threaten global biodiversity. However, the relative influence of habitat loss and landscape fragmentation, the spatial patterning of remaining habitat, remains unclear. If landscape pattern affects population size, managers may be able to design landscapes that mitigate habitat loss. We present the results of a mensurative experiment designed to test four habitat loss vs. fragmentation hypotheses. Unlike previous studies, we measured landscape structure using quantitative, spatially explicit habitat distribution models previously developed for two species: Blackburnian Warbler (Dendroica fusca) and Ovenbird (Seiurus aurocapilla). We used a stratified sampling design that reduced the confounding of habitat amount and fragmentation variables. Occurrence and reoccurrence of both species were strongly influenced by characteristics at scales greater than the individual territory, indicating little support for the random-sample hypothesis. However, the type and spatial extent of landscape influence differed. Both occurrence and reoccurrence of Blackburnian Warblers were influenced by the amount of poor-quality matrix at 300- and 2000-m spatial extents. The occurrence and reoccurrence of Ovenbirds depended on a landscape pattern variable, patch size, but only in cases when patches were isolated. These results support the hypothesis that landscape pattern is important for some species only when the amount of suitable habitat is low. Although theoretical models have predicted such an interaction between landscape fragmentation and composition, to our knowledge this is the first study to report empirical evidence of such nonlinear fragmentation effects. Defining landscapes quantitatively from an organism-based perspective may increase power to detect fragmentation effects, particularly in forest mosaics where boundaries between patches and matrix are ambiguous. Our results indicate that manipulating landscape pattern may reduce negative impacts of habitat loss for Ovenbird, but not Blackburnian Warbler. We emphasize that most variance in the occurrence of both species was explained by local scale or landscape composition variables rather than variables reflecting landscape pattern.     

Controlled release, blind test of DNAPL remediation by ethanol flushing

A dense nonaqueous phase liquid (DNAPL) source zone was established within a sheet-pile isolated cell through a controlled release of perchloroethylene (PCE) to evaluate DNAPL remediation by in-situ cosolvent flushing. Ethanol was used as the cosolvent, and the main remedial mechanism was enhanced dissolution based on the phase behavior of the water-ethanol-PCE system. Based on the knowledge of the actual PCE volume introduced into the cell, it was estimated that 83 L of PCE were present at the start of the test. Over a 40-day period, 64% of the PCE was removed by flushing the cell with an alcohol solution of approximately 70% ethanol and 30% water. High removal efficiencies at the end of the test indicated that more PCE could have been removed had it been possible to continue the demonstration. The ethanol solution extracted from the cell was recycled during the test using activated carbon and air stripping treatment. Both of these treatment processes were successful in removing PCE for recycling purposes, with minimal impact on the ethanol content in the treated fluids. Results from pre- and post-flushing partitioning tracer tests overestimated the treatment performance. However, both of these tracer tests missed significant amounts of the PCE present, likely due to inaccessibility of the PCE. The tracer results suggest that some PCE was inaccessible to the ethanol solution which led to the inefficient PCE removal rates observed. The flux-averaged aqueous PCE concentrations measured in the post-flushing tracer test were reduced by a factor of 3 to 4 in the extraction wells that showed the highest PCE removal compared to those concentrations in the pre-flushing tracer test.     

The influence of pH on the degradation of phenol and chlorophenols by potassium ferrate

This paper presents information concerning the influence of solution pH on the aqueous reaction between potassium ferrate and phenol and three chlorinated phenols: 4-chlorophenol (CP), 2,4-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP). The redox potential and aqueous stability of the ferrate ion, and the reactivity of dissociating compounds, are known to be pH dependent. Laboratory tests have been undertaken over a wide range of pH (5.8-11) and reactant concentrations (ferrate:compound molar ratios of 1:1 to 8:1). The reactivity of trichloroethylene was also investigated as a reference compound owing to its non-dissociating nature. The extent of compound degradation by ferrate was found to be highly pH dependent, and the optimal pH (maximum degradation) decreased in the order: phenol/CP, DCP, TCP; at the optimal pH the degree of degradation of these compounds was similar. The results indicate that for the group of phenol and chlorophenols studied, the presence of an increasing number of chlorine substituent atoms corresponds to an increasing reactivity of the undissociated compound, and a decreasing reactivity of the dissociated compound.     

Observations of 2,4,6-trichlorophenol degradation by ozone

The aqueous reactivity of 2,4,6-trichlorophenol (TCP) with ozone has been studied at laboratory-scale using a simple gas bubble/liquid contacting system. Degradation rate constants were measured directly and found to be 7.6 and 77.2 M(-1)s(-1) at pH 2 and 7.5, respectively. At pH 7.5, 10 min of ozonation ( identical with 15 mM ozone consumption) achieved a 90% degradation of TCP, which corresponded to the release of approximately 2 mol Cl(-) per mol TCP. The presence of hydrogen peroxide in solution did not significantly increase the TCP degradation but increased the overall dechlorination to 2.7 mol Cl(-) per mol TCP. The presence of humic acid (HA) in solution was found to enhance the degradation rate of TCP at low relative HA concentrations (<0.6 g/g HA:TCP), but to reduce the rate at higher HA concentrations.     

The degradation of endocrine disruptor di-n-butyl phthalate by UV irradiation: a photolysis and product study

The direct photolysis of an important endocrine disruptor compound, di-n-butyl phthalate (DBP), has been investigated under monochromatic UV irradiation at 254 nm over a wide pH range (3-11). The investigation was carried out under idealized conditions and has considered both reaction kinetics and the degradation mechanism. It was found that more than 90% of DBP can be degraded within an hour of irradiation in water. A simple model has been developed and used to predict the initial DBP photolysis rate constant at different pH values and initial DBP concentrations. The major decomposition mechanism of DBP is believed to involve the hydrolytic photolysis of the carbon in the alpha and/or beta-position of the ester chain with the production of aromatic carboxylic derivatives. Additionally, multi-degradation pathways are proposed for acid-catalyzed hydrolytic photolysis (pH 3-5), which was found to be useful in explaining the photo-degradation of DBP under acidic conditions. The use of 254 nm UV to photo-degrade DBP was found to be a relatively fast and clean process, especially in neutral to basic conditions.     

Climate change effects on river flow to the Baltic Sea

River flow to the Baltic Sea originates under a range of different climate regimes in a drainage basin covering some 1,600,000 km2. Changes to the climate in the Baltic Basin will not only affect the total amount of freshwater flowing into the sea, but also the distribution of the origin of these flows. Using hydrological modeling, the effects of future climate change on river runoff to the Baltic Sea have been analyzed. Four different climate change scenarios from the Swedish Regional Climate Modelling Programme (SWECLIM) were used. The resulting change to total mean annual river flow to the Baltic Sea ranges from -2% to +15% of present-day flow according to the different climate scenarios. The magnitude of changes within different subregions of the basin varies considerably, with the most severe mean annual changes ranging from -30% to +40%. However, common to all of the scenarios evaluated is a general trend of reduced river flow from the south of the Baltic Basin together with increased river flow from the north.     

Dissolved organic matter mediated aquatic transport of chlorinated dioxins

The bioavailability and environmental fate of extremely hydrophobic environmental contaminants such as chlorinated dioxins is linked to their solubility characteristics in water. Solubilities of three chlorinated dioxins, viz., 1,2,3,7-T₄CDD, 1,2,3,4,7-P₅CDD, and 1,2,3,4,7,8-H₆CDD, were determined in pure water using a glass bead generator column technique, and their enhanced solubilities in the presence of several dissolved humic fractions quantified at 20, 30 and 40°C. The strengths of these interactions between chlorodioxins and the dissolved humic substances, viz., a fulvic acid, a humic acid, and Aldrich humic acid, were examined using simple thermodynamic calculations. A new partition/association coefficient, K_oc (mobile) is defined.     

Sustainable Development and Institutional Design: The Example of the Mersey Basin Campaign

The Mersey Basin Campaign was established in 1985 in the North West of England to address continuing problems of water quality and associated landward dereliction of the River Mersey and its tributaries. The Campaign's premise that water quality should be improved both for its own sake and as a stimulus to regeneration has proved to be well founded and has subsequently been extended to embrace community action to help nurture watercourse improvement and care. The Campaign can now be seen as a model for engaging co-ordinated environmental action through a partnership approach. This paper explores the nature of the Mersey Basin Campaign as an example of the new structures which are being developed in order to help deliver the new environmentalpolicy agenda. It is argued that the Campaign stands as a model for what will become an increasing need to develop focused environmental planning and management at the sub-regional and regional scales.