Reducing mine water network energy requirements

Increasing energy efficiency and reducing water consumption are two of the key requirements in moving toward a more sustainable mining industry. This paper demonstrates a method of determining the lowest energy option for a mine/mill water system network. The method uses a linear programming algorithm to compare different possible combinations of supplying water to mine and mill consumers. First, a site water balance is determined and then every major water consumer and source is specified. Water sources may require pumping, cooling and/or treatment before the water meets the specifications of the water consumer. The amount of energy required for each water source to supply each consumer is calculated and then the model is solved to minimize power consumption. An example is used to illustrate the method.     

Aerial contamination of fruit through wet deposition and particulate dry deposition

The current state of knowledge concerning the processes and pathways which lead to the contamination of fruit crops by non-gaseous airborne contaminants is reviewed. Given the wide range of fruit canopies which occur, it is necessary to look for generic factors which affect the contribution of each of these processes and pathways to distribution through the canopy, losses from the canopy back to the atmosphere, and the fate of particle-bound substances once attached to the canopy. This latter stage represents perhaps the greatest source of uncertainty in determining levels of contamination. For wet deposition, the controlling factors appear to be the ability of the canopy surface to store precipitated water, and the interaction of the contaminant species with the leaf cuticle, which appears to act as an ion exchange medium, selectively accumulating certain ionic species. Where possible, models and parameterisations are provided for these stages. A summary is given of current data requirements for those cases where this is not possible.     

Determination of fumonisins in milk

Abstract

Fumonisin B₁ (FB₁) and fumonisin B₂ (FB₂) were determined in milk by liquid chromatography (LC) following immunoaffinity column cleanup. Recoveries from milk spiked with 5–50 ng each fumonisin/ml averaged 79–109%. The aminopentol hydrolysis product of FB₁ (AP₁) was determined by LC after cleanup on a C₁₈solid phase phase extraction column; mean recoveries were 69–83% at spiking levels of 50–100 ng AP₁/ml milk. Detection limits were of the order 3–7 ng/ml for FB₁ and FB₂, and 20–25 ng/ml for AP₁. A stability study showed no losses of FB₁ and FB₂ in milk under conditions of freezing, refrigeration and boiling. A transmission study using four cows dosed with pure FB₁, either orally (1.0 and 5.0 mg FB₁/kg b.w.) or by i.v. injection (0.05 and 0.20 mg FB₁/kg b.w.) showed no detectable residues of FB, or AP₁ in the milk, with or without hydroiytic treatment with β‐glucuronidase/sulfatase to liberate any conjugates.     

Market reactions to Australian boutique resource investor presentations

This paper examines the market reactions to 817 investor presentations by 326 Australian resource firms and finds evidence suggesting these events are informative. Furthermore, the positive returns do not reverse over the following 15 days, which contrasts with previous investor presentation research. However, consistent with the prior literature, extended long run cumulative abnormal returns are not significantly different from zero. This paper also documents stronger reactions to first time presenting firms, presentations that are announced to the market and firms exhibiting at the Africa Downunder and Excellence in Oil & Gas conferences. There are also stronger reactions for firms with lower ownership concentration. Examining boutique resource firm investor presentations adds to the existing disclosure and dissemination literature due to the presence of relatively high information asymmetry in the extractive industries, a unique setting, which contrasts with previous studies.     

Population dynamics of the invasive bryozoan Membranipora membranacea along a 450-km latitudinal range in the subarctic northwestern Atlantic

Thermal environment is often regarded as a key determinant of distribution limits in marine invertebrates and hence may represent one of the most important barriers to invasion by non-indigenous species. For the first time in the subarctic northwestern Atlantic, we investigated variation in the timing and magnitude of settlement, recruitment, and colony cover of the recently (early 2000s) introduced bryozoan Membranipora membranacea on the kelp Saccharina longicruris and how this variation relates to changes in sea temperature (thermal histories) across eight sites spanning a 450-km latitudinal range between southwestern Newfoundland and southeastern Labrador, Canada. We show that (1) up to 61 % of the variation in settlement, recruitment, and colony cover was explained by sea temperature alone, with highest and lowest abundances at warmest and coldest sites, respectively; (2) between-site differences in rates of sea cooling explained 85 % of the variation in settler abundance; (3) varying the temporal window over which data were aggregated increased the explanatory power of sea temperature to as much as 98 % for settlement and recruitment, and 86 % for colony cover; (4) exposure to waves and surface area of colonies improved relationships between sea temperature and settlement and recruitment by up to 11 %; and (5) recruit abundance was a strong predictor of colony cover, explaining as much as 89 % of the variation. Consistently low abundances of settlers and recruits at the northern tip of Newfoundland and southern tip of Labrador suggest that M. membranacea is nearing its northern distribution limit in the northwestern Atlantic. Our findings extend knowledge of population dynamics of M. membranacea in the northwestern Atlantic, while highlighting the complexity of the interactions between physical and biological factors and processes that affect population dynamics in invertebrates with planktonic larvae in predominantly cold marine habitats.     

Models for preserving species diversity with backup coverage

The problem of selecting land for preservation of species has been a rich and active area of research over the past two decades. Typically, reserve selection models have tried to maximize species diversity by preserving areas that contain the greatest number of species. However, several studies have shown that seldom do these species-rich areas contain the rarest species most in need of protection. Most reserve selection models seek to maximize diversity by choosing parcels so that all species are covered by or represented in at least one parcel. This approach would usually be expected to result in coverage by a single parcel for the rarest species, especially for those that do not coincide with more abundant species. It is precisely these rare species, however, that would be lost or whose survivability would be most challenged, if the single parcels in which they are represented became unavailable due to some unforeseen event. In this paper, we introduce to reserve selection models the concept of secondary, or backup, coverage of species. Briefly stated, a species is said to have backup representation in the system of reserves if it is covered by, or represented in, two or more parcels. Having backup coverage guarantees that every species is still covered in the event that a natural or man-made catastrophe makes a given parcel uninhabitable. The results show that backup coverage can be obtained at little additional cost (as expressed by the number of parcels selected). Bi-objective formulations that trade-off primary with backup coverage show that backup coverage can be guaranteed for larger numbers of species with little reduction in primary coverage.     

Archival tagging of subadult and adult common thresher sharks (Alopias vulpinus) off the coast of southern California

The common thresher shark (Alopias vulpinus) is a secondary target species of the California drift gillnet fishery (CA-DGN) and supports a growing recreational fishery in California waters. This study used archival tags to examine the movement patterns and habitat preferences of common threshers of the size range captured in the CA-DGN (>120 cm fork length). Depth and temperature-logging archival tags were deployed on 57 subadult and adult common threshers in the Southern California Bight. Tags from five individuals (8.8%) were recovered, and 154 days of data were successfully obtained from four of these. By night, shark movements were primarily limited to waters above the thermocline, which ranged in depth from 15 to 20 m. Sharks were significantly deeper by day, and daytime vertical distribution consisted of two distinct modes: a ‘shallow mode’ (wherein sharks occupied only the upper 20 m of the water column) and a ‘deep mode’ (characterized by frequent vertical excursions below the thermocline). This modal switch is interpreted as relating to regional differences in abundance of surface-oriented prey and prey in deeper water. Maximum dive depth was 320 m, greatest dive duration was 712 min, minimum temperature experienced during a dive was 9.1°C, and dive descent rate was significantly greater than ascent rate. Sharks inhabited waters corresponding to a sea surface temperature range of 16 to 21°C. The nocturnal depth distribution of common threshers has implications for management of drift gillnet deployment depths in the CA-DGN.     

Sources of Suspended-Sediment Flux in Streams of the Chesapeake Bay Watershed: A Regional Application of the SPARROW Model1

Brakebill, John W., Scott W. Ator, and Gregory E. Schwarz, 2010. Sources of Suspended-Sediment Flux in Streams of the Chesapeake Bay Watershed: A Regional Application of the SPARROW Model. Journal of the American Water Resources Association (JAWRA) 46(4): 757-776. DOI: 10.1111/j.1752-1688.2010.00450.x Abstract: We describe the sources and transport of fluvial suspended sediment in nontidal streams of the Chesapeake Bay watershed and vicinity. We applied SPAtially Referenced Regressions on Watershed attributes, which spatially correlates estimated mean annual flux of suspended sediment in nontidal streams with sources of suspended sediment and transport factors. According to our model, urban development generates on average the greatest amount of suspended sediment per unit area (3,928 Mg/km²/year), although agriculture is much more widespread and is the greatest overall source of suspended sediment (57 Mg/km²/year). Factors affecting sediment transport from uplands to streams include mean basin slope, reservoirs, physiography, and soil permeability. On average, 59% of upland suspended sediment generated is temporarily stored along large rivers draining the Coastal Plain or in reservoirs throughout the watershed. Applying erosion and sediment controls from agriculture and urban development in areas of the northern Piedmont close to the upper Bay, where the combined effects of watershed characteristics on sediment transport have the greatest influence may be most helpful in mitigating sedimentation in the bay and its tributaries. Stream restoration efforts addressing floodplain and bank stabilization and incision may be more effective in smaller, headwater streams outside of the Coastal Plain.