Setting goals and choosing appropriate reference sites for restoring mine pit lakes as aquatic ecosystems: Case study from south west Australia

Pit lakes may form when open cut mining leaves a pit void behind that fills with ground and surface water. Often replacing terrestrial ecosystems that existed prior to mining, the pit lake may offer an alternative ecosystem with aquatic biodiversity values that can be realised through planned restoration. Restoration theory and mine closure regulatory requirements guides us toward restoring disturbed systems towards landscapes that are of regional value and relevance. However, how do we identify a restoration target for a novel aquatic habitat that did not exist prior to the new post-mining landscape? This paper presents a process of first identifying and then surveying local analogue aquatic systems to provide a direction for pit lake restoration efforts and achievement criteria for pit lake relinquishment. We illustrate this process using a case study from a sand mining operation located amongst wetlands in south western Australia. The company mines silica sands following mechanical removal of topsoil and then extraction of the ore from below the water table by dredging. Assessment of wetland and riparian vegetation in the surrounding area was completed through the establishment and measurement of temporary monitoring transects across five natural wetlands in the Kemerton area with several more visited and observations made. Distinct zonation of vegetation was found across each wetland, although typically wetland basins were unvegetated or filled with younger woody plants with patchy distributions. Fringing riparian vegetation consisted of few species (commonly Melaleuca rhaphiophylla and Lepidosperma longitudinale) but community composition and structure were variable between wetlands. The pattern of vegetation seen across natural wetlands was best explained by topography and soil chemistry with low lying areas more likely to experience regular flooding and accumulate organic matter and nutrients. We consider that, with good planning, rehabilitation, monitoring and management interventions to achieve a restoration trajectory, these new mining pit lakes can positively contribute to regional ecological values

Mine closure of pit lakes as terminal sinks: best available practice when options are limited?

In an arid climate, pit lake evaporation rates can exceed influx rates, causing the lake to function as a hydraulic terminal sink, with water levels in the pit remaining below surrounding groundwater levels. We present case studies from Western Australia for two mines nearing closure. At the first site, modelling indicates that waste dump covers for the potentially acid forming (PAF) material would not be successful over the long term (1,000 years or more). The second site is a case study where PAF management is limited by the current waste rock dump location and suitable cover materials. Pit lake water balance modelling using Goldsim software indicated that both pit lakes would function as hydraulic terminal sinks if not backfilled above long-term equilibrium water levels. Poor water quality will likely develop as evapoconcentration increases contaminant concentrations, providing a potential threat to local wildlife. Even so, the best current opportunity to limit the risk of contaminant migration and protect regional groundwater environments may be to limit backfill and intentionally produce a terminal sink pit lake

The seeds of divergence: the economy of French North America, 1688 to 1760

Generally, Canada has been ignored in the literature on the colonial origins of divergence with most of the attention going to the United States. Late nineteenth century estimates of income per capita show that Canada was relatively poorer than the United States and that within Canada, the French and Catholic population of Quebec was considerably poorer. Was this gap long standing? Some evidence has been advanced for earlier periods, but it is quite limited and not well-suited for comparison with other societies. This thesis aims to contribute both to Canadian economic history and to comparative work on inequality across nations during the early modern period. With the use of novel prices and wages from Quebec—which was then the largest settlement in Canada and under French rule—a price index, a series of real wages and a measurement of Gross Domestic Product (GDP) are constructed. They are used to shed light both on the course of economic development until the French were defeated by the British in 1760 and on standards of living in that colony relative to the mother country, France, as well as the American colonies. The work is divided into three components. The first component relates to the construction of a price index. The absence of such an index has been a thorn in the side of Canadian historians as it has limited the ability of historians to obtain real values of wages, output and living standards. This index shows that prices did not follow any trend and remained at a stable level. However, there were episodes of wide swings—mostly due to wars and the monetary experiment of playing card money. The creation of this index lays the foundation of the next component. The second component constructs a standardized real wage series in the form of welfare ratios (a consumption basket divided by nominal wage rate multiplied by length of work year) to compare Canada with France, England and Colonial America. Two measures are derived. The first relies on a “bare bones” definition of consumption with a large share of land-intensive goods. This measure indicates that Canada was poorer than England and Colonial America and not appreciably richer than France. However, this measure overestimates the relative position of Canada to the Old World because of the strong presence of land-intensive goods. A second measure is created using a “respectable” definition of consumption in which the basket includes a larger share of manufactured goods and capital-intensive goods. This second basket better reflects differences in living standards since the abundance of land in Canada (and Colonial America) made it easy to achieve bare subsistence, but the scarcity of capital and skilled labor made the consumption of luxuries and manufactured goods (clothing, lighting, imported goods) highly expensive. With this measure, the advantage of New France over France evaporates and turns slightly negative. In comparison with Britain and Colonial America, the gap widens appreciably. This element is the most important for future research. By showing a reversal because of a shift to a different type of basket, it shows that Old World and New World comparisons are very sensitive to how we measure the cost of living. Furthermore, there are no sustained improvements in living standards over the period regardless of the measure used. Gaps in living standards observed later in the nineteenth century existed as far back as the seventeenth century. In a wider American perspective that includes the Spanish colonies, Canada fares better. The third component computes a new series for Gross Domestic Product (GDP). This is to avoid problems associated with using real wages in the form of welfare ratios which assume a constant labor supply. This assumption is hard to defend in the case of Colonial Canada as there were many signs of increasing industriousness during the eighteenth and nineteenth centuries. The GDP series suggest no long-run trend in living standards (from 1688 to circa 1765). The long peace era of 1713 to 1740 was marked by modest economic growth which offset a steady decline that had started in 1688, but by 1760 (as a result of constant warfare) living standards had sunk below their 1688 levels. These developments are accompanied by observations that suggest that other indicators of living standard declined. The flat-lining of incomes is accompanied by substantial increases in the amount of time worked, rising mortality and rising infant mortality. In addition, comparisons of incomes with the American colonies confirm the results obtained with wages— Canada was considerably poorer. At the end, a long conclusion is provides an exploratory discussion of why Canada would have diverged early on. In structural terms, it is argued that the French colony was plagued by the problem of a small population which prohibited the existence of scale effects. In combination with the fact that it was dispersed throughout the territory, the small population of New France limited the scope for specialization and economies of scale. However, this problem was in part created, and in part aggravated, by institutional factors like seigneurial tenure. The colonial origins of French America’s divergence from the rest of North America are thus partly institutional

Turfgrass Management at Your Fingertips: Information Delivered Through Smart Phone Technology

Turfgrass managers and Extension professionals often require real-time, in-situ pest diagnosis, management, and recommendations. Advanced smart phones have become important tools for industry professionals and allow flexibility while traveling or away from the office. We have developed an application (app) for iPhone® and Blackberry® smart phones that allows access to a library of resources in the field. The Turfgrass Management application contains a full suite of weed, disease, insect, and turfgrass species resources. More than 2,500 subscriptions from over 30 countries have been downloaded. We present evidence of the usefulness of delivery of information through this mobile technology