Biotic, temporal and spatial variability of tritium concentrations in transpirate samples collected in the vicinity of a near-surface low-level nuclear waste disposal site and nearby research reactor

The results of a 21 month sampling program measuring tritium in tree transpirate with respect to local sources are reported. The aim was to assess the potential of tree transpirate to indicate the presence of sub-surface seepage plumes.Transpirate gathered from trees near low-level nuclear waste disposal trenches contained activity concentrations of ³H that were significantly higher (up to ∼700 Bq L⁻¹) than local background levels (0-10 Bq L⁻¹). The effects of the waste source declined rapidly with distance to be at background levels within 10s of metres. A research reactor 1.6 km south of the site contributed significant (p < 0.01) local fallout ³H but its influence did not reach as far as the disposal trenches.The elevated ³H levels in transpirate were, however, substantially lower than groundwater concentrations measured across the site (ranging from 0 to 91% with a median of 2%). Temporal patterns of tree transpirate ³H, together with local meteorological observations, indicate that soil water within the active root zones comprised a mixture of seepage and rainfall infiltration. The degree of mixing was variable given that the soil water activity concentrations were heterogeneous at a scale equivalent to the effective rooting volume of the trees. In addition, water taken up by roots was not well mixed within the trees. Based on correlation modelling, net rainfall less evaporation (a surrogate for infiltration) over a period of from 2 to 3 weeks prior to sampling seems to be the optimum predictor of transpirate ³H variability for any sampled tree at this site.The results demonstrate successful use of ³H in transpirate from trees to indicate the presence and general extent of sub-surface contamination at a low-level nuclear waste site.     

种间关系预测(ICE)模型在水质基准研究中的应用

水质基准研究主要是基于物种的实验室测试的毒性数据开展的。对于一些毒性数据相对缺乏的化学品,水质基准研究就会受到一定的影响。本文从水质基准研究方法的角度,阐述了种间关系预测(ICE)的基本原理和基本方法,系统介绍了ICE模型的毒性预测方法在水质基准研究中的应用,并通过锌的ICE案例研究证明了模型在中国的可利用性。同时,对ICE模型的不确定性和适用性进行了分析。最后,对ICE模型存在的问题和未来的发展方向进行了探索和展望。     

THE EFFECTS OF MINE ACID ON THE POND RIVER WATERSHED IN WESTERN KENTUCKY1

ABSTRACT: H₂SO₄ (sulfuric acid) is formed by a chemical process that occurs in unreclaimed coal mines. The highly toxic acid then flows into the lower swamp areas where it causes considerable damage to the ecosystem. The major effect of the acid is the mass destruction of thousands of trees and various other phreatophytic plants. The contamination is so serious that most of the wildlife has migrated out of the affected area of the swamp in order to survive. Certain geological features such as coal bearing monadanocks make the area somewhat sensitive to mining activities and related geologic hazards. New methods of mine acid abatement make the concept of mass reclamation more realistic than at any time in the past. The constant annihilation of swamp life and processes emphasizes the urgent need for reclamation of the swamp.     

Potential of largemouth bass as vectors of 137Cs dispersal

We conducted a radio telemetry study on the movements of potentially contaminated largemouth bass between Steel Creek, a restricted access (137)Cs contaminated stream on the Savannah River Site (located in South Carolina, USA), and the publicly accessible Savannah River. Largemouth bass were relatively mobile in lower Steel Creek and the portion of the Savannah River near Steel Creek, and there was considerable movement between these two habitats. Largemouth bass had home ranges of about 500 linear meters of shoreline in the Savannah River but sometimes moved long distances. Such movements occurred primarily during the spawning season, largely upstream, and increased when water levels were changing or elevated. However, approximately 90% of the largemouth bass observations were within 10 km of Steel Creek. The total quantity of (137)Cs transported into the Savannah River by largemouth bass was much less than transported by water and suspended sediments discharged from Steel Creek. We conclude that largemouth bass from the Savannah River Site are unlikely to be responsible for long distance dispersal of substantial radiological contamination in the Savannah River.     

Modelling the trade-off between fire and grazing in a tropical savanna landscape, northern Australia.

As savannas are widespread across northern Australia and provide northern rangelands, the sustainable use of this landscape is crucial. Both fire and grazing are known to influence the tree-grass character of tropical savannas. Frequent fires open up the tree layer and change the ground layer from perennials to that dominated by annuals. Annual species in turn produce copious quantities of highly flammable fuel that perpetuates frequent, hot fires. Grazing reduces fuel loads because livestock consumes fuel-forage. This trade-off between fire and grazing was modelled using a spatially explicit, process-orientated model (SAVANNA) and field data from fire experiments performed in the Victoria River District of northern Australia. Results of simulating fire (over 40 years) with minimal or no grazing pressure revealed a reduction in the shrub and woody plants, a reduction in grasses, and no influence on the tree structure given mild fires. While mature trees were resistant to fire, immature trees, which are more likely associated with the shrub layer, were removed by fire. The overall tree density may be reduced with continual burning over longer time periods because of increasing susceptibility of old trees to fire and the lack of recruitment. Increases in stocking rates created additional forage demands until the majority of the fuel load was consumed, thus effectively suppressing fire and reverting to the grazing and suppressed fire scenario where trees and shrubs established.     

Advancing climate compatible development: lessons from southern Africa

Climate compatible development (CCD) has emerged as a new concept that bridges climate change adaptation, mitigation and community-based development. Progress towards CCD requires multi-stakeholder, multi-sector working and the development of partnerships between actors who may not otherwise have worked together. This creates challenges and opportunities that require careful examination at project and institutional levels and necessitates the sharing of experiences between different settings. In this paper, we draw on the outcomes from a multi-stakeholder workshop held in Mozambique in 2012, the final in a series of activities in a regional project assessing emerging CCD partnerships across southern Africa. The workshop involved policymakers, researchers and representatives from NGOs and the private sector. We employ a content analysis of workshop notes and presentations to identify the progress and challenges in moving four case study countries (the Democratic Republic of the Congo, Mozambique, Zambia and Zimbabwe) towards CCD pathways, by exploring experiences from both project and policy levels. To advance institutional support for the development of successful CCD policies, practices and partnerships, we conclude that there is a need for: (a) institutional development at the national level to strengthen coordination and more clearly define roles and responsibilities across sectors, based on the identification of capacity and knowledge gaps; (b) partnership development, drawing on key strengths and competences of different stakeholders and emphasising the roles of the private sector and traditional authorities; (c) learning and knowledge-sharing through national and regional fora; and (d) development of mechanisms that permit more equitable and transparent distribution of costs and benefits. These factors can facilitate development of multi-stakeholder, multi-level partnerships that are grounded in community engagement from the outset, helping to translate CCD policy statements into on-the-ground action.     

The effect of resuspending sediment contaminated with antifouling paint particles containing Irgarol 1051 on the marine macrophyte Ulva intestinalis

The effect of resuspending sediment contaminated with Irgarol 1051 based antifouling paint particles on the green macroalga Ulva intestinalis was examined. U. intestinalis was also exposed to sediment spiked with Irgarol 1051. The macroalga were exposed over 21 days to the resuspension of sediments containing 61.2 mg kg(-1) of antifouling paint particles containing Irgarol 1051 that provided aqueous Irgarol 1051 concentrations of approximately 0.3 microg l(-1), Irgarol 1051 and appropriate controls. The growth response was compared with that for 'clean' sediment. Resuspension of sediment was associated with reduced growth when compared to seawater alone. Resuspension of sediment spiked with Irgarol 1051 was associated with a greater reduction in growth, with growth being significantly reduced when sediment containing antifouling paint particles was resuspended. The data suggest that the prolonged disturbance of sediments containing antifouling paint particles in marinas represents a potential and as yet unquantified hazard to photosynthetic organisms.     

Adaptations to climate change,drought and desertification: local insights to enhance policy in southern Africa

The impacts of climate change, drought and desertification are closely interlinked, and most acutely experienced by populations whose livelihoods depend principally on natural resources. Given the increases in extreme weather events projected to affect the Southern Africa region, it is essential to assess how household and community-level adaptations have been helped or hindered by institutional structures and national policy instruments. In particular, there is a need to reflect on efforts related to the United Nations’ environmental conventions to ensure that policies support the maintenance of local adaptations and help retain the resilience of socio-economic and environmental systems. This paper examines three interlinked drivers of adaptation: climate change, desertification and drought, assessing the extent to which international and national policy supports local adaptive strategies in three countries in southern Africa. We show that while common ground exists between desertification and climate change adaptations at the policy level, they are insufficiently mainstreamed within broader development approaches. Similarly, there are some overlaps between policy-driven and autonomous local adaptations, but the mutually supportive links between them are poorly developed. Further efforts to integrate local adaptation strategies within policy could increase local resilience to environmental change, while also contributing to wider development goals.     

Biomass:polystyrene co-pyrolysis coupled with metal-modified zeolite catalysis for liquid fuel and chemical production

Journal of Material Cycles and Waste Management - Biomass and waste polystyrene plastic (ratio 1:1) were co-pyrolysed followed by catalysis in a two-stage fixed bed reactor system to produce...