Bioaccumulation factors and multivariate analysis of heavy metals of three edible fish species from the Barekese reservoir in Kumasi,Ghana

The Barekese reservoir has seen persistent degradation for decades through anthropogenic activities within its catchment. In spite of this, heavy metal pollution profile of fish species of the reservoir is not well studied. Total concentrations of Hg, Cd, Ni, and Cr were analyzed in muscle tissues of 45 edible fish species comprising (Tilapia zilli, Oreochromis niloticus, and Heterotis niloticus) from the reservoir. The examined fish species showed varying bioaccumulative factors for detected metals. A PCA biplot revealed that Cd showed association with all examined fish species used in the study indicating that Cd in the reservoir is biologically available for uptake by all examined fish species. A dendrogram of cluster analysis also revealed that Cd and Cr are in one cluster indicating their associations and similarities to a common anthropogenic source. The study suggests that anthropogenic activities are possible sources of heavy metal pollution in the Barekese reservoir and, hence, the examined fish species could be used to monitor the levels of Ni, Cr, Hg, and Cd in the reservoir.     

A Regional Survey of the Microbiological Water Quality along the Shoreline of the Southern California Bight

A regional survey of the microbiological water quality along the shoreline of the Southern California Bight (SCB), from Point Conception south to Ensenada, Mexico, was conducted during August, 1998, by 36 agencies under the coordination of the Southern California Coastal Water Research Project (SCCWRP). Microbiological water quality was assessed by calculating the percentage of shoreline-mile-days that exceeded bacterial indicator thresholds for total and fecal coliforms, total/fecal ratios, and enterococci. Sample sites were selected using a stratified random sampling approach, with the SCB recreational shoreline divided into six strata: high- and low-use sandy beaches, high- and low-use rocky shoreline, and perennial and ephemeral freshwater outlets. Samples were collected on a weekly basis at a total of 253 sites, beginning on August 2^nd, 1998 and continuing for five weeks. Samples were analyzed by 22 participating labs using their normal methods (multiple tube fermentation, membrane filtration, Colilert® and/or Enterolert®). All labs met testing criteria established through intercalibration exercises and quality control check samples distributed during the sampling period. Nearly 95% of the shoreline-mile days did not exceed daily and monthly bacterial indicator thresholds, demonstrating good bacteriological water quality along the SCB shoreline. Freshwater outlets, comprised mainly of storm drains, had the poorest water quality with 60% and 40% of the shoreline-miles exceeding monthly and daily thresholds, respectively. Freshwater outlets were also more likely to demonstrate exceedances by multiple indicators at a single site, and repeat exceedances at sites over the five-week period. Compared with the southern California beaches, Mexican beaches had nearly 5 times the number of exceedances for total and fecal coliforms, and nearly 8 times the number of exceedances for total/fecal ratios.     

Constructing “not Implausible” Climate and Economic Scenarios for Egypt

A space of “not-implausible” scenarios for Egypt's future under climate change is defined along two dimensions. One depicts representative climate change and climate variability scenarios that span the realm of possibility. Some would not be very threatening. Others portend dramatic reductions in average flows into Lake Nassar and associated increases in the likelihood of year to year shortfalls below critical coping thresholds; these would be extremely troublesome, especially if they were cast in the context of increased political instability across the entire Nile Basin. Still others depict futures along which relatively routine and relatively inexpensive adaptation might be anticipated. The ability to adapt to change and to cope with more severe extremes would, however, be linked inexorably to the second set of social–political–economic scenarios. The second dimension, defined as “anthropogenic” social/economic/political scenarios describe the holistic environment within which the determinants of adaptive capacity for water management, agriculture, and coastal zone management must be assessed. This revised version was published online in July 2006 with corrections to the Cover Date.     

The fairness of PAYT systems: some guidelines for decision-makers

Although the whole idea behind the PAYT approach is to develop a fairer system of waste charges than currently used, there still remains a number of issues that need to be considered when designing any given application of the PAYT principle, bearing in mind the variety of possible PAYT systems and the set of factors that influence their implementation. We assume that the perception of the system's fairness affects acceptance and thus participation, in the sense that the higher the perceived fairness the higher will be the acceptance of the system and, therefore, the higher the participation will be. Consequently, when it comes to analysing the acceptance of the implementation of a PAYT system or its effective functioning, waste management decision-makers should be interested in making sure that the system is perceived as fair in order to ensure a high participation rate. In addition, from a social point of view, decision-makers and politicians may be interested in the consequences of the operation of the system for other social values and in its impacts on particular groups of participants. This presentation examines the conditions for fairness and the considerations that should be taken into account so as to design a fair PAYT system in a specific municipality.     

Exchange-rate economics for the resources sector

The paper provides an account of aspects of exchange-rate economics that are of particular relevance to the resources sector. The issues discussed include exchange-rate volatility and the risk management practices used to deal with it, the role of productivity differences across countries, and the impact of a booming resources sector on the country's exchange rate. The discussion is organized around a simple stylized model that emphasizes the quantity theory of money and purchasing power parity as a long-run link between prices and exchange rates.     

Commodity currencies and currency commodities

There is a large literature on the influence of commodity prices on the currencies of countries with a large commodity-based export sector, such as Australia, New Zealand, and Canada (“commodity currencies”). There is also the idea that because of pricing power, the value of currencies of certain commodity-producing countries affects commodity prices, such as metals, energy, and agricultural-based products (“currency commodities”). This paper merges these two strands of the literature to analyze the simultaneous workings of commodity and currency markets. We implement the approach by using the Kalman filter to estimate jointly the determinants of the prices of these currencies and commodities. Included in the specification is an allowance for spillovers between the two asset types. The methodology is able to determine the extent that currencies are indeed driven by commodities, or that commodities are driven by currencies, over the period 1975–2005.     

Effective monitoring of agriculture: a response

The development of effective agricultural monitoring networks is essential to track, anticipate and manage changes in the social, economic and environmental aspects of agriculture. We welcome the perspective of Lindenmayer and Likens (J. Environ. Monit., 2011, 13, 1559) as published in the Journal of Environmental Monitoring on our earlier paper, "Monitoring the World's Agriculture" (Sachs et al., Nature, 2010, 466, 558-560). In this response, we address their three main critiques labeled as 'the passive approach', 'the problem with uniform metrics' and 'the problem with composite metrics'. We expand on specific research questions at the core of the network design, on the distinction between key universal and site-specific metrics to detect change over time and across scales, and on the need for composite metrics in decision-making. We believe that simultaneously measuring indicators of the three pillars of sustainability (environmentally sound, social responsible and economically viable) in an effectively integrated monitoring system will ultimately allow scientists and land managers alike to find solutions to the most pressing problems facing global food security.     

Montane meadows in the Sierra Nevada: comparing terrestrial and aquatic assessment methods

We surveyed montane meadows in the northern Sierra Nevada and southern Cascades for two field seasons to compare commonly used aquatic and terrestrial-based assessments of meadow condition. We surveyed (1) fish, (2) reptiles, (3) amphibians, (4) aquatic macroinvertebrates, (5) stream geomorphology, (6) physical habitat, and (7) terrestrial vegetation in 79 meadows between the elevations of 1,000 and 3,000?m. From the results of those surveys, we calculated five multi-metric indices based on methods commonly used by researchers and land management agencies. The five indices consisted of (1) fish only, (2) native fish and amphibians, (3) macroinvertebrates, (4) physical habitat, and (5) vegetation. We compared the results of the five indices and found that there were significant differences in the outcomes of the five indices. We found positive correlations between the vegetation index and the physical habitat index, the invertebrate index and the physical habitat index, and the two fish-based indices, but there were significant differences between indices in both range and means. We concluded that the five indices provided very different interpretations of the condition in a given meadow. While our assessment of meadow condition changed based on which index was used, each provided an assessment of different components important to the overall condition of a meadow system. Utilizing a multimetric approach that accounts for both terrestrial and aquatic habitats provides the best means to accurately assess meadow condition, particularly given the disproportionate importance of these systems in the Sierra Nevada landscape.     

Evaluation of Numerical Modeling Methods for the Management of Produced Water Discharges in the Coastal Region with a Canadian Case Study

This study aims at evaluating two numerical methods for 3D simulation of marine pollutant dispersion problems: the random walk particle tracking (RWPT) method and an explicit second-order finite difference method (FDM) for assessing produced water discharges from offshore oil platform. Test cases in a steady flow field were used to evaluate the efficiency and accuracy of simulating pollutant concentration profiles obtained using both the FDM and RWPT method in comparison with an analytical solution. Additionally, a field study was conducted to simulate the lead concentration distribution of produced water discharged from an oil platform off Canada’s east coast, based on the Princeton Ocean Model modeling the ocean flow in the study area with field verifications. Results indicate that, with proper configuration of grid resolution and particle resolution, both FDM and RWPT method can provide accurate results with reasonable computational costs for complex field cases. Particularly, the satisfactory 3D simulations of marine pollutant dispersion in the far field by both FDM and RWPT numerical methods enable effective assessment and management of offshore waste discharges.     

Status and trends of circumpolar peregrine falcon and gyrfalcon populations

Ambio - The peregrine falcon (Falco peregrinus) and the gyrfalcon (Falco rusticolus) are top avian predators of Arctic ecosystems. Although existing monitoring efforts are well established for both...