Characterisation of acid mine drainage in a high rainfall mountain environment, New Zealand

The Stockton coal mine lies at 700-1100 m above sea level in a mountainous orographic precipitation zone on the West Coast of the South Island of New Zealand. Rainfall exceeds 6000 mm/year and arrives with frequent flood events that can deliver > 200 mm/day. Streams vary in discharges by up to two orders of magnitude over a time scale of hours. Pyritic waste rock at the mine interacts chemically with even the most intense rainfall, and almost all runoff is acidic to some degree. In the most intense rain event recorded in this study (> 10 mm/hour), dilution of acid mine drainage (AMD) occurred and pH rose from 3 to > 5 over several hours, with stream discharge at a monitoring point rising from < 0.5 to > 100 cumecs. However, most rain events of similar magnitude are less intense, longer duration, and only raise AMD pH to ~ 4 with similar high discharges. Results presented here for Stockton confirm that it is the intensity of rain events on the hourly scale, rather than the total amount of rainwater delivered to the site, that governs the amount and composition of AMD generated during flood events. Stream discharge loads of dissolved iron and aluminium range from ~ 20 to 1000 kg/hour. Dissolved sulfate and acidity loads are typically ~ 500 kg/hour but can exceed 20 tonnes/hour in rain events.First flush effects observable elsewhere around the world involving peak metal loads following dry periods or seasonal changes are not obvious at Stockton due to the high and variable rainfall environment. Dissolved Fe concentrations may be limited in runoff waters by precipitation of jarosite and schwertmannite, especially when rainfall is sufficiently intense to raise pH to 4 or higher. These minerals are widespread in the exposed waste rock on site. Likewise, precipitation of alunite may occur as pH rises in rain events, but no field evidence for this has been observed.     

A digital wind gust recorder

The instrument was a byproduct of an undergraduate final year project on wind power which was carried out by the Department of Mechanical Engineering of the University of Liverpool.The windmill test site was on an exposed, rocky island where there was no history of weather recording but a long tradition of violent winds.Field experience during the winter months suggested that corrosion fatigue arising from wind buffeting and salt spray would rank equally with maximum wind pressure as criteria of failure and if modern materials, so convenient for forming aerodynamic surfaces, were to be used then limited life concepts would need to be considered. This called for more knowledge of wind variations at the test site. A complete wind spectrum taken on chart recording instruments would have been ideal but since such such refined devices were not available the instrument to be described was designed.The only wind measuring instrument which was available was a rotating cup anemometer. This supplied an alternating voltage proportional to its rotational speed. It also operated a gear driven microswitch which could give an integrated “miles of wind” reading on an electromagnetic counter.Briefly the e.m.f. generated by the anemometer (Fig. 1) was matched against a pre-set voltage corresponding to the required gust velocity. When this was exceeded an appropriate counter was operated. Only the rising e.m.f. was significant. The subsequent fall was ignored. Initially three stages were incorporated which reported the gusts rising through forty, fifty and sixty knots, respectively. These recorded on separate counters. All basic settings were based on pitot-static speed determinations in a wind tunnel.     

Use of Potassium for Treatment and Control of Zebra Mussel Infestation in Industrial Fire Protection Water Systems

Zebra mussels, first discovered in the Great Lakes in 1988, have frequently been detected in fire protection systems. However, the potential for large-scale infestations has not been established. It is clear that even small numbers of mussels can cause problems in areas that have small-diameter piping or in sprinkler system nozzles, if shells are flushed down-stream during emergency use.This paper will discuss the development of a method of zebra mussel control that limited interference with normal system operations when used at Niagara Mohawk's Dunkirk Steam Station. Because oxygen is often depressed in these systems and limits mussels survival and growth, it was established that by monitoring oxygen alone, or in combination with veliger or mussel larval monitoring, high-risk areas for mussel infestation could be determined. In previous laboratory research, it had already been determined that concentrations of potassium in excess of 100 mg/L would lead to quick mortality in adult zebra mussels. These results, along with a biofouling risk assessment completed at Dunkirk Steam Station, were used to develop and implement a successful treatment of the high-risk areas in the plant's fire protection water systems using potassium in the form of potash as the controlling agent.     

Routine production or symbolic analysis? India and the globalisation of architectural services

Developments in information technology have reduced the need for spatial proximity in the geography of architectural employment: computer-based drafting allows for better standardisation and more efficient production of project information, whilst electronic communication links make the immediate transfer of this information possible across long distances. The ability to compress time and space may be paving the way to the relocation of architectural production facilities from higher-wage to lower-wage regions: numerous examples already exist of firms that have adopted this strategy to reduce their overheads.

Thus far, discussion of the viability and desirability of this emerging trend has been hampered by its close focus on the type of work carried out, and a consequently narrow view of its costs and benefits. Remote drafting is seen as a cheap form of professional north-south exploitation in architecture's intellectual circles that should be ignored if not deplored. By stressing the connection between the task and the culture in which it is developed, this paper seeks to produce a broader, alternative perspective, which identifies the several limitations of current off-shore collaborations but also points out possible future strengths, development strategies, and necessary environmental conditions.

The Indian context provides an opportunity to highlight analogies and differences between the recent growth of the export-oriented IT industry and the construction of a colonial professional practice at the turn of the twentieth century. If properly acknowledged by the domestic profession and considered by policy-makers, the development of a framework for distant architectural collaborations could be used not only to support the local design sector and bring the contested components of its post-colonial tradition in sharper focus and possibly closer together, but also to respond to the many challenges posed by the country's economic policies, growth, and infrastructural conditions.     

Reconceptualising territoriality and spatial planning: insights from the sea

The concept of territoriality and its relationship to the focus and substance of spatial planning is the subject of much interest at the present time and this paper seeks to contribute to the debate by stepping into the sea. The first part of the paper establishes a framework for considering the spatial planning implications of changing conceptions of territoriality, outlining key sources of territorial innovation and their implications in terms of the development of new units and styles of governance, new challenges for planning practice, and the potential for feedback informing the development of planning theory. The application of the framework is then illustrated in the second part of the paper with reference to the emerging field of maritime spatial planning and in particular to the pioneering work that is being undertaken in Europe. This work is testing established notions of territoriality by highlighting the strong and growing connections between the land and the sea. Here some of the key implications for future spatial planning practice are identified. These indicate that there is a growing recognition of the need for innovation in the territorial units of governance in maritime regions and in the themes, processes and methods of spatial planning in these areas. The paper concludes with some observations on the implications of these findings for the theory of spatial planning.     

A neural network bid/no bid model: the case for contractors in Syria

Despite the crucial importance of the ‘bid/no bid’ decision in the construction industry, it has been given little attention by researchers. This paper describes the development and testing of a novel bid/no bid model using the artificial neural network (ANN) technique. A back‐propagation network consisting of an input buffer with 18 input nodes, two hidden layers and one output node was developed. This model is based on the findings of a formal questionnaire through which key factors that affect the ‘bid/no bid’ decision were identified and ranked according to their importance to contractors operating in Syria. Data on 157 real‐life bidding situations in Syria were used in training. The model was tested on another 20 new projects. The model wrongly predicted the actual bid/no bid decision only in two projects (10%) of the test sample. This demonstrates a high accuracy of the proposed model and the viability of neural network as a powerful tool for modelling the bid/no bid decision‐making process. The model offers a simple and easy‐to‐use tool to help contractors consider the most influential bidding variables and to improve the consistency of the bid/no bid decision‐making process. Although the model is based on data from the Syrian construction industry, the methodology would suggest a much broader geographical applicability of the ANN technique on bid/no bid decisions.     

The effects of a chlorinated discharge and a thermal outfall on the structure and composition of the aquatic macroinvertebrate communities in the sheep river, Alberta, Canada

Physico-chemical and biological samples were collected from 12 sampling stations over a 13-month period to assess the effects of a small town's chlorinated sewage discharge and a thermal discharge on the Sheep River's macroinvertebrate communities. During the study, the chlorinated effluent plume was restricted to the left third of the channel for approx. 0.5 km at which point the effluent was thoroughly mixed due to an abrupt change in channel direction. Within the concentrated 0.5 km chlorinated plume, total residual chlorine TRC concentrations periodically exceeded 5.0 mg l⁻¹. Stations were categorized into similar community assemblages on the basis of species abundance and composition using heirarchical cluster analysis. Stations immediately downstream of the thermal outfall and those within the chlorinated plume had distinctly different structure and were dominated by Oligochaeta. Multiple discriminant analysis indicated that temperature was the principle discriminating variable immediately below the thermal discharge while the chlorinated sewage (MCSE) variable was the most important discriminant function within the chlorinated effluent plume. Following complete mixing of the effluent plume within the stream channel (0.6 km downstream of outfall), macroinvertebrate structure and diversity improved, presumably due to nutrient enrichment and dilution of TRC below detectable levels.     

Design and Laboratory Evaluation of a Sequential Spot Sampler for Time-Resolved Measurement of Airborne Particle Composition

A new sampling approach has been developed to enable affordable, time-resolved monitoring of particulate chemical composition, and more generally to provide concentrated samples of airborne particles. Using a newly developed, moderated water-based condensational growth technology, individual particle samples are deposited in a 1-mm diameter dry “spot.” The moderated condensation technology enables this collection with minimal temperature rise, providing robust collection for volatile constituents. Measured collection efficiencies are above 95% for particles in the size range from 0.010 μm to 2.5 μm. A set of 20 or more time-resolved samples, plus blanks, may be collected onto a multiwell collection plate. For chemical analysis the plate is returned to the laboratory, and placed directly into a modified autosampler, without extraction or preparation. The autosampler handles the addition of eluent, extraction, and sample injection without user manipulation. This article presents the design and laboratory evaluation of a 1.5 L/min sampling rate version of this system.

Copyright 2014 American Association for Aerosol Research