Long-term evolution of highly alkaline steel slag drainage waters

© 2015, Springer International Publishing Switzerland. The disposal of slag generated by the steel industry can have negative consequences upon the surrounding aquatic environment by the generation of high pH waters, leaching of potentially problematic trace metals, and rapid rates of calcite precipitation which smother benthic habitats. A 36-year dataset was collated from the long-term ambient monitoring of physicochemical parameters and elemental concentrations of samples from two steel slag leachate-affected watercourses in northern England. Waters were typified by elevated pH ( > 10), high alkalinity, and were rich in dissolved metals (e.g. calcium (Ca), aluminium (Al), and zinc (Zn)). Long-term trend analysis was performed upon pH, alkalinity, and Ca concentration which, in addition to Ca flux calculations, were used to highlight the longevity of pollution arising as a result of the dumping and subsequent leaching of steel slags. Declines in calcium and alkalinity have been modest over the monitoring period and not accompanied by significant declines in water pH. If the monotonic trends of decline in alkalinity and calcium continue in the largest of the receiving streams, it will be in the region of 50–80 years before calcite precipitation would be expected to be close to baseline levels, where ecological impacts would be negligible

The potential use of exhausted open pit mine voids as sinks for atmospheric CO2: insights from natural reedbeds and mine water treatment wetlands

Abandoned surface mine voids are often left to flood, forming pit lakes. Drawing simple but important lessons from experiences with compost-based passive remediation systems for acidic mine waters, an alternative end-use for open pit mine voids is proposed: gradual infilling with organic material, which can serve as a long-term sink for atmospheric CO2, whilst ameliorating or eventually eliminating sustained evaporative water loss and acidic water pollution. Key to the success of this approach is the suppression of methane release from organic sediments flooded with sulfate-rich mine waters: the presence of modest amounts of sulfate (which is typically abundant in mine waters) inhibits the activity of methanogenic bacteria. This explains why gas release studies of mine water treatment wetlands never report methane emissions; CO2 is the only greenhouse gas emitted, and this is clearly not at levels sufficient to undo the benefits of wetlands as net CO2 sinks. While the compete infilling of open pits with organic sediments might take a very long time, only minimal maintenance would be needed, and if carbon trading markets finally mature, a steady income stream could be obtained to cover the costs, thus extending the economic life of the mine site far beyond cessation of mining

Can aggregate quarry silt lagoons provide resources for wading birds?

Wading birds have declined across Europe as the intensification of lowland agriculture has resulted in the loss and degradation of wetland areas. Lowland aggregate extraction sites that incorporate areas of fine, waste sediments deposited in silt lagoons have the potential to be restored for wader conservation. We set out to determine the potential value of silt lagoons to wading birds by comparing the water quality, sediment profiles, aquatic invertebrate abundance and diversity (prey availability) and wader site use at five sites representing various stages of active aggregate extraction and restoration for conservation purposes. Wader counts were conducted monthly over a twelve month period using replicated scan samples, and the invertebrate communities studied during the breeding and autumn migration season (June–September). Water quality variables were similar between sites, but sediments from active quarries were dominated by moderately sorted fine sands in comparison to the coarser sediment profiles of restored areas. June and September there was no significant difference in invertebrate diversity between sites, however richness was significantly lower on quarry sites and total abundance a factor of ten higher at restored sites than on silt lagoons, with the dominant taxa similar across all sites. Waders used all sites; albeit at lower abundance and richness on silt lagoons and two species were recorded breeding on active silting sites. We conclude that the fine, uniform sediments of modern silt lagoons limited invertebrate diversity and abundance, diminishing the value of silt lagoons to waders. Simple low-cost intervention measures increasing substrate heterogeneity and creating temporary ponds could increase invertebrate richness and abundance, and enhance the conservation potential of these sites

Understanding Addiction as a Developmental Disorder: An Argument for a Developmentally Informed Multilevel Approach

Substance abuse and drug addiction are two of the most common psychopathologies among the general population. While a host of risk factors are associated with the onset of drug abuse and drug addiction, there is a growing body of evidence pointing to the powerful influence of early adverse experiences, both child neglect and maltreatment, as well as drug use and abuse in parents and/or primary caretakers. We consider the case for drug addiction as a developmental disorder, outlining the need to consider the role of genetic, epigenetic, and neurobiological factors alongside experiences of adversity at key stages of development. Such a multilevel approach within a developmental framework has the potential to reframe our understanding of how addiction emerges and is maintained, and is essential if we are to identify the mechanisms underlying this disorder to better inform effective treatment and prevention across the generations

The quality of monetary policy and inflation performance: globalization and its aftermath

With a few unfortunate exceptions the last three decades have seen reductions in inflation around the world to the point that many would argue that further improvements in price stability would offer only limited welfare gains. This experience is the result of many factors, some of which are country-specific. In this paper we seek to isolate one of the factors, namely, the improvement in the quality of monetary policy. There are two novel aspects to the study. Firstly, we essentially estimate a gravity-like model. Secondly, we propose generally a more exhaustive analysis of the potential role of a large number of institutional factors than has been done before. Briefly, we find that institutional factors play a role in explaining inflation relative to the US experience, which is used as the benchmark. Nevertheless, any reduction in inflation stemming from greater central bank autonomy is a feature of the 1980s and early 1990s. Thereafter, central banks in the OECD look very much alike.globalization; inflation differentials; monetary policy strategy; institutional change

Complex Adaptive Systems and Quantitative Reasoning in an Interdisciplinary STEM Mathematics Classroom

In this presentation we will share outcomes from the Real STEM project, which provides professional development for rural teachers in the Georgia Coastal Plains supporting implementation of interdisciplinary STEM courses as well as STEM modules in mathematics and science courses. Real STEM includes a number of innovative student-active strategies for teaching including: Understanding by Design (UbD) approaches to teaching for understanding, problem-based learning (PBL), place-based education (PBE), complex adaptive systems (CAS) thinking, and quantitative reasoning (QR). QR is the mathematical underpinning of the projects. The projects are ongoing so we will report our results on impact on teacher practice and student learning to this point. We will conclude with a discussion of how the projects may address issues of engagement for rural, low socio-economic status student populations in STEM in Central America and the Caribbean