Prolonged reproductive consequences of short-term biomass loss in seaweeds

This study describes the reproductive collapse of a large giant-kelp forest (Macrocystis pyrifera; Point Loma, southern California, USA) and the dynamics of its subsequent recovery. High-frequency sampling within a 100-m² area, combined with a 3-year reproduction time-series from four other sites over a broad depth gradient, were used to (1) quantify temporal and spatial patterns of change in size and fertility of adult sporophytes, and (2) examine physical and biological factors that regulate such changes. Giant-kelp sporophytes have the potential for continuous reproduction, yet from March to November 1999, sporophytes at the high-frequency sampling site went from completely sloughing (actively releasing zoospores) to completely sterile, despite a relatively constant biomass of sporogenous tissues. This shift to sterility was rapid, with 65% of sporophytes ceasing to slough during late-June/early-July 1999, and did not co-occur with stressful physical conditions (i.e. high temperatures, low nutrients, or high wave intensity). Instead, the cessation of reproductive output corresponded to an episodic, sublethal amphipod-grazing event that stripped blade biomass from all sporophytes. Although the grazer infestation affected the entire kelp forest, peaks in grazer abundance were localized, moving through the population during late spring and summer, and causing patchiness in sporophyte size and fertility on a scale of meters. The reproductive collapse was size-dependent, since smaller sporophytes were the first to cease sloughing. The grazing event waned in the fall and sporophyte vegetative growth rapidly recovered lost biomass (within ~2 months). Such growth, however, occurred at the expense of the production of sporogenous tissue and caused a prolonged period (>4 months) of decreased reproductive output. These results suggest a trade-off between sporophyte growth and reproduction, allowing short-term disturbances to have lasting impacts on the reproductive output of giant-kelp populations.     

Sustainability and the primary extraction industries: theories and practice

This paper reflects on how sustainability is being interpreted both theoretically and in practice for the primary extraction industries. Two contrasting perspectives can be adopted: one states that continued extraction of non-renewable resources is a necessary part of sustainable development, whilst the other states that extraction of these resources must be greatly reduced or even eliminated. It is shown that these different approaches can be traced back to underlying, often unarticulated, assumptions about the acceptability of trade-offs between different societal goals; attitudes towards uncertainties in scientific analysis and the reliability of management systems; and the perceived appropriateness of system boundaries at different conceptual scales. These assumptions are founded in the self-perception of organisations and individuals about their roles in society, and the cultural context within which these organisations and individuals define their raison d'être.     

A two-generational reproductive toxicity study of zinc in rats

A two-generation reproductive toxicity study of zinc chloride (ZnCl(2)) was conducted in rats. F(o) male and female rats were administered 0.00 (control), 7.50 (low), 15.00 (mid) and 30.00 (high) mg/kg/day of ZnCl(2). Selected F(1) male and female rats were exposed to the same doses received by their parents (F(o)). Exposure of F(0) parental rats to ZnCl(2) showed significant reduction in fertility, viability (days 0 and 4), and the body weight of F(1) pups from the high-dose group but caused no effects on litter size, weaning index, and sex ratio. Similarly, the continued exposure of F(1) parental rats to ZnCl(2) also reduced fertility, liter size, viability (day 0), and the body weight of F(2) pups within the high-dose group but caused no effects on weaning index and sex ratio. Exposure of ZnCl(2) to F(0) and F(1) parental males resulted in a significant reduction in their body weights, and the F(0) and F(1) parental females did not show any significant difference in their body weights compared to their control groups. However, the postpartum dam weights of both F(0) and F(1) female rats were significantly reduced compared to their controls. Exposure of ZnCl(2) to F(o) and F(1) generation parental rats did not produce any significant change of their clinical signs as well as their clinical pathology parameters, except the alkaline phosphotase (ALK) level, which showed an upward trend in both sexes of both generations. Exposure of ZnCl(2) to F(0) rats resulted in a reduction of brain, liver, kidney, spleen and seminal vesicles weights of males and in the spleen and uterus of females. Similarly, exposure of F(1) rats to ZnCl(2) also resulted in reduction of brain, liver, kidney, adrenal, spleen, prostate and seminal vesicles weights of males and in spleen and uterus of females. ZnCl(2) exposure resulted in grossly observed gastro-intestianla (GI) tract, lymphoreticular/hematopoietic, and reproductive tract lesions in parental rats in both generations. Reduced body fat was also recorded in F(1) parental rats.     

Effect of housing geometry on the performance of Chemcatcher passive sampler for the monitoring of hydrophobic organic pollutants in water

Passive sampling of pollutants in water has been gaining acceptance for environmental monitoring. Previously, an integrative passive sampler (the Chemcatcher) was developed and calibrated for the measurement of time weighted average concentrations of hydrophobic pollutants in water. Effects of physicochemical properties and environmental variables (water temperature and turbulence) on kinetic and thermodynamic parameters characterising the exchange of analytes between the sampler and water have been published. In this study, the effect of modification in sampler housing geometry on these calibration parameters was studied. The results obtained for polycyclic aromatic hydrocarbons show that reducing the depth of the cavity in the sampler body geometry increased the exchange kinetics by approximately twofold, whilst having no effect on the correlation between the uptake and offload kinetics of analytes. The use of performance reference compounds thus avoids the need for extensive re-calibration when the sampler body geometry is modified.     

Changes in sewage sludge carbon forms along a treatment stream

The behaviour and fate of macronutrients and pollutants in sewage sludge applied to the land are affected by the chemical composition of the sludge organic matter, which in turn is influenced by both sewage source and by sewage treatment processes. In this study, (13)C nuclear magnetic resonance (NMR) spectroscopy was used to characterise the organic matter of sludges collected at three different points along the treatment stream of a municipal sewage works with a domestic catchment. Sludge at the first point, an undigested liquid (UL) sludge, had a substantially different composition to the anaerobically digested (AD) and dewatered sludge cake (DC) materials, which were similar to each other. In particular, the UL sludge contained more alkyl C than the AD or DC sludges. All three sludges were found to contain mobile alkyl C that is poorly observed using the cross polarisation (CP) technique, necessitating the use of the less sensitive, but more quantitatively reliable direct polarisation (DP) technique to obtain accurate distributions of C types.     

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.     

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.     

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.     

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.     

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.