Barley, a potential species for initial reclamation of saline composite tailings of oil sands

The oil sands industry in Alberta (Canada) has developed the composite tailings (CT) process to reduce the fluid fine tails resulting from the processing of oil sands. This process uses a chemical coagulant (gypsum or alum) to produce aggregated fines (clay), so they are retained with the coarse sand fraction of the extraction tailings to form CT, from which fines-free water is released relatively quickly compared with untreated tailings. The resulting CT and CT waters are saline-sodic, with Na+, SO4(2-), and Cl- being the dominant ions. When freshly deposited, the CT deposits are too soft for access by reclamation equipment, and the time required for these deposits to remove the water sufficiently to support traffic is uncertain. A greenhouse study was designed to determine the suitability of barley (Hordeum vulgare L.) for reclamation of fresh CT deposits and to evaluate benefits of peat amendments. This study assessed germination, early plant growth, chlorophyll content, and survival of barley growing in alum- and gypsum-treated CT, with and without peat amendment. Ion and trace metal accumulation in the root and shoot tissues of barley was determined. Amendment of CT with peat improved germination, survival, and growth of barley, but did not prevent leaf injury (probably due to Na and Cl- and possibly multiple nutrient deficiency). Field studies will be undertaken to validate our greenhouse results suggesting that barley could be used to improve dewatering of the freshly deposited substrates, reduce soil erosion, and facilitate leaching of ions by root penetration into the substrate.     

Social network analysis and valid Markov chain Monte Carlo tests of null models

Analyses of animal social networks derived from group-based associations often rely on randomisation methods developed in ecology (Manly, Ecology 76:1109–1115, 1995) and made available to the animal behaviour community through implementation of a pair-wise swapping algorithm by Bejder et al. (Anim Behav 56:719–725, 1998). We report a correctable flaw in this method and point the reader to a wider literature on the subject of null models in the ecology literature. We illustrate the importance of correcting the method using a toy network and use it to make a preliminary analysis of a network of associations among eagle rays.

Aqueous, solid and gaseous partitioning of selenium in an oxic sandy soil under different microbiological states

The aim of this study was to investigate the role of microorganisms on the behaviour of selenium in natural soil maintained under strictly aerobic conditions. Six-day batch experiments were performed with soils constrained to different microbiological states, either by sterilisation or by adding organic substrates. Selenium was added to the soil as selenite. The distribution of selenium in the gaseous, liquid and solid phases of the batch was measured. Selenium partitioning between the various solid phases was investigated by chemical sequential extractions. Active microorganisms played major effects on the distribution of selenium within the soil. On the one hand, microorganisms could promote selenium volatilisation (in relatively small amounts), leading to the spreading of selenium compounds outside the soil. On the other hand, microbial activities increased both amount of selenium retained by the soil and the strength of its retention (less exchangeable selenium), making selenium less susceptible to remobilisation.     

The reuse of reclaimed water for irrigation around the Mediterranean Rim: a step towards a more virtuous cycle?

Regional Environmental Change - Climate change and a growing population around the Mediterranean Rim are increasing the need for water and, consequently, the pressure on resources in terms of both...     

Perceptions of climate change risks in primary resource use industries: a survey of the Canadian mining sector

A survey documenting how climate change is perceived, experienced, and responded to in the Canadian mining sector was administered to industry practitioners at the Prospectors & Developers Association of Canada annual meeting. Nine key findings from the survey are discussed: (1) The Canadian mining sector is sensitive to climate-related conditions. (2) Climate change is perceived to be having a negative impact on mining operations. (3) Companies are taking action to manage the current impacts. (4) Cost and uncertainty are commonly identified barriers to adapting to current climate change. (5) Future climate change is expected to have impacts for the industry. (6) Climate change projections are perceived as threats by the majority of respondents. (7) Despite the perceived threat, companies are not currently taking action to plan for future impacts. (8) Cost and uncertainty are commonly identified barriers to adapting to future climate change impacts. (9) The mining sector is currently making efforts to reduce greenhouse gas emissions. The survey is exploratory in nature, establishing a baseline for targeted research to assess in greater detail the vulnerability of mining to climate change.     

Jack pine growth and elemental composition are affected by saline tailings water

In the processing of oil sands from Alberta's Athabasca formation, large quantities of alkaline, saline tailings and associated process-affected waters are produced. These waters may have a negative effect on plants used in reclamation of mined areas in this region of the northern boreal forest. In the present study, we examined the effects of process-affected water on the growth and elemental composition of jack pine (Pinus banksiana Lamb.) seedlings. Seedlings were grown in sand culture, and treated with tailings water to which mineral nutrients had been added. One-month-old seedlings were treated for 14 d, and all measured growth parameters were reduced. Growth and shoot elemental composition were also measured in seven-month-old seedlings that were treated for 10 wk with process-affected water. Shoots had significantly elevated levels of Na, Cl, S, P, B, and Sr, and significantly reduced levels of Fe, Mo, Ba, and K. The relationships between elemental composition and seedling growth and injury were examined using multiple regression. Growth rates, dry weights, and carotenoid content were reduced, but were not related to shoot elemental composition. Needle necrosis was positively related to tissue Na and Cl. Results indicate that reclamation planning must consider substrate Na and Cl levels when planting jack pine on tailings-affected sites.     

Courtship and reproduction in<Emphasis Type="Italic"> Carybdea sivickisi</Emphasis> (Cnidaria: Cubozoa)

Courtship and fertilization events in cubozoans have received little attention from biologists, and much of what we know about these processes is based on conjecture or scant anecdotal evidence. I set out to describe these processes in the cubozoan Carybdea sivickisi by observing mature medusae in vitro. Mature adults engage in courtship during which spermatophores are transferred from the male to the female, who then inserts the gametes into her manubrium. Females accepted multiple spermatophores from multiple males, and only produced one embryo strand. This study also provides evidence that the presence of conspicuous velar spots on the females bell margin is a signal of sexual maturity, and that sexual maturity was not reached in either sex until individuals had a bell diameter of at least 5 mm.Communicated by R.J. Thompson, St. Johns     

Suitability of altai wildrye (Elymus angustus) and slender wheatgrass (Agropyron trachycaulum) for initial reclamation of saline composite tailings of oil sands

The reclamation of freshly produced composite or consolidated tailings (CT) is a challenge for the Oil Sands Industry in the boreal forest of Western Canada. CT tailings materials are characterized by a relatively high salinity (dominated by sodium, sulphate and chloride) and a high pH (8-9). A greenhouse study was conducted to determine the germination, survival, injury and early plant growth of two grass species recommended for land reclamation, altai wildrye (Elymus angustus Trin) and slender wheatgrass (Agropyron trachycaulum Link Malte), growing in two different oil sand CT tailings (alum-CT and gypsum-CT), with and without peat amendment. Ion accumulation in the resulting plant tissues was determined. Our results showed that slender wheatgrass was most affected by the tailings at the germination stage, while for altai wildrye, the early growth stage was the most sensitive stage. Alum-CT had similar or less negative impact on plants than gypsum-CT. Amendment of CT with peat limited the reduction in germination and growth that was recorded in plants growing directly in CT. Based on these results, recommendations were made to improve reclamation strategies.