The effect of complex formation on the adsorption characteristics of heavy metals

In most aqueous environmental systems, inorganic and organic metal complexes represent a significant contribution to the total soluble metal. Metal adsorption is often a highly pH-dependent phenomena. Such behavior can generally be attributed to changes in metal speciation with solution acidity as well as variation in the extent of surface protonation. Thus, because adsorbability may vary drastically between different metal species, (e.g. Cu²⁺ (aq) compared to CuOH⁺) a knowledge of metal species distribution is essential to understanding and interpreting metal adsorption behavior.Organic complexation has been reported to enhance, suppress and have no perceptible effect on trace metal adsorption. Such differences arise because adsorption depends on factors such as the ligand/metal ratio, adsorbability of the free ligand, and various solution parameters (e.g. pH). Most important in determining the effect of complexation on adsorption is the adsorbability of the resulting complexes. Thus, it is difficult to make generalizations about the influence of organic complexation on metal adsorption.Adsorption of metal complexes is frequently reported to be predominantly coulombic in nature; that is, binding of an anionic or cationic complex to an oppositely charged colloidal particle. However, electrostatic forces can often represent an insignificant contribution to the total free energy of adsorption and can be overshadowed by chemical reactions with the surface, hydrogen bonding, and hydrophobic effects.     

Understanding long-term baseflow water quality trends using a synoptic survey of the ground water-surface water interface, central Wisconsin

The relationship between stream water quality and landscape activities is difficult to evaluate where the principal source of stream flow is ground water seepage because the average travel time from ground water recharge areas to stream discharge positions can be on the order of decades. We tested the idea that past and future baseflow water quality can be predicted based on a synoptic survey of ground water recharge age-dates (based on chlorofluorocarbon [CFC] measurements) and water quality measurements obtained at the ground water-surface water interface. In this study we (i) characterize the discharge-weighted age distribution and water quality of ground water seepage into the Little Plover River (LPR); (ii) use this information to backcast and forecast baseflow NO(3)(-) concentrations; and (iii) evaluate NO(3)(-) backcasts against historical baseflow data (1960 to 2000). The discharge-weighted apparent CFC age of ground water seepage into the LPR was 23.7 (+/-7) yr. Baseflow backcasts matched the four decade rise of baseflow NO(3)(-) from 2 to 8 mg L(-1). Baseflow forecasts included three scenarios. Scenario A projects the historical rise of NO(3)(-) in the LPR basin's ground water recharge through 2050. Scenario B projects a leveling off of NO(3)(-) in ground water recharge in the year 2000. Scenario C projects a leveling off in the year 1985. Under Scenario A, LPR baseflow NO(3)(-) will increase steadily from 8 to 19 mg L(-1) between 2000 and 2050. Under scenarios B and C baseflow NO(3)(-) will plateau at 13 mg L(-1) in 2030 and at 10 mg L(-1) in 2010, respectively. The approach developed in this study can be used to (i) reconstruct historical baseflow water quality patterns in the absence of long-term monitoring data and (ii) project the effects of potential management decision on future water quality.     

How Science Contributes to Environmental Reporting in British Newspapers: A Case Study of the Reporting of Global Warming and Climate Change

This article examines the role of science in environmental reporting in a number of British newspapers. The findings indicated that in reporting about global warming and climate change, the views of scientists were used to give legitimacy to the content of articles. However, in both the tabloids and broadsheets, there was little evidence provided, in the form of data, to substantiate the claims being made. Furthermore, uncertainties about global warming were not explored effectively. Newspaper reports tended to focus on the potential consequences of global warming, but made little attempt to address the suspected causes that would inevitably involve criticism of highly consumptive lifestyles in the west.     

The impacts of road transport on air quality in the Greater Manchester region, UK: policies towards a sustainable transport system

The transport-induced air quality problems of the Greater Manchester region are examined. The problems are defined in terms of economic and social factors leading to the development of a car-based economy. The impacts of transport emissions on the natural and built environment and human health are discussed. The administrative, legislative and pollution control responses to the problem are examined. The nature of future air quality problems will require an integration of traffic management, land use, public transport and pollution control policies if they are to be satisfactorily addressed. A series of policy recommendations towards this end are included.     

Evaluation and classification of severity for 176 genes on an expanded carrier screening panel

Background

Disease severity is important when considering genes for inclusion on reproductive expanded carrier screening (ECS) panels. We applied a validated and previously published algorithm that classifies diseases into four severity categories (mild, moderate, severe, and profound) to 176 genes screened by ECS. Disease traits defining severity categories in the algorithm were then mapped to four severity-related ECS panel design criteria cited by the American College of Obstetricians and Gynecologists (ACOG).

Methods

Eight genetic counselors (GCs) and four medical geneticists (MDs) applied the severity algorithm to subsets of 176 genes. MDs and GCs then determined by group consensus how each of these disease traits mapped to ACOG severity criteria, enabling determination of the number of ACOG severity criteria met by each gene.

Results

Upon consensus GC and MD application of the severity algorithm, 68 (39%) genes were classified as profound, 71 (40%) as severe, 36 (20%) as moderate, and one (1%) as mild. After mapping of disease traits to ACOG severity criteria, 170 out of 176 genes (96.6%) were found to meet at least one of the four criteria, 129 genes (73.3%) met at least two, 73 genes (41.5%) met at least three, and 17 genes (9.7%) met all four.

Conclusion

This study classified the severity of a large set of Mendelian genes by collaborative clinical expert application of a trait-based algorithm. Further, it operationalized difficult to interpret ACOG severity criteria via mapping of disease traits, thereby promoting consistency of ACOG criteria interpretation.

     

A plasma display window?-The shifting baseline problem in a technologically mediated natural world

Humans will continue to adapt to an increasingly technological world. But are there costs to such adaptations in terms of human well being? Toward broaching this question, we investigated physiological effects of experiencing a HDTV quality real-time view of nature through a plasma display “window.” In an office setting, 90 participants (30 per group) were exposed either to (a) a glass window that afforded a view of a nature scene, (b) a plasma window that afforded a real-time HDTV view of essentially the same scene, or (c) a blank wall. Results showed that in terms of heart rate recovery from low-level stress the glass window was more restorative than a blank wall; in turn, a plasma window was no more restorative than a blank wall. Moreover, when participants spent more time looking at the glass window, their heart rate tended to decrease more rapidly; that was not the case with the plasma window. Discussion focuses on how the purported benefits of viewing nature may be attenuated by a digital medium.     

Assessing alternative aquaculture technologies: life cycle assessment of salmonid culture systems in Canada

This study employed life cycle assessment (LCA) to quantify and compare the potential environmental impacts of culturing salmonids in a conventional marine net-pen system with those of three reportedly environmentally-friendly alternatives; a marine floating bag system; a land-based saltwater flow-through system; and a land-based freshwater recirculating system. Results of the study indicate that while the use of these closed-containment systems may reduce the local ecological impacts typically associated with net-pen salmon farming, the increase in material and energy demands associated with their use may result in significantly increased contributions to several environmental impacts of global concern, including global warming, non-renewable resource depletion, and acidification. It is recommended that these unanticipated impacts be carefully considered in further assessments of the sustainability of closed-containment systems and in ongoing efforts to develop and employ these technologies on a larger scale.