Polyurethane foam unit (PFU) systems were collected from 11 lakes and three rivers in the Yunnan Plateau, China and, the PFU extrusion liquids were analyzed for organochlorine pesticides (OCPs) by gas chromatography with electron capture detection (GC-ECD). The concentrations of pp'-DDE, HCB and HCHs were undetectable to 1.86 microgl-1 (mean 0.27 microgl-1), undetectable to 0.72 microgl-1 (mean 0.11 microgl-1), and 0.24-21.95 microgl-1 (mean 7.39 microgl-1) respectively in lakes; and those in rivers were undetectable to 0.23 microgl-1 (mean 0.08 microgl-1), 0.68-2.93 microgl-1 (mean 1.70 microgl-1), and 2.71-37.56 microgl-1 (mean 17.01 microgl-1) respectively. Notably, some residue levels of OCPs exceeded the US National Recommended Water Quality Criteria, implying Yunnan has levels of OCPs potentially harmful to human health. Further, the contamination by OCPs showed an obvious spatial distribution pattern. Amongst the lakes, Dianchi, Xingyun, Lugu and Yangzonghai had the highest OCP levels dominated by beta-HCH, whereas among rivers, Nujiang and Lancang Rivers had the highest contents of OCPs dominated by alpha-HCH. This demonstrates that HCHs are the predominant contaminants and some point sources of HCHs may still exist in Yunnan. The pollution levels in Yunnan were compared with other studies, suggesting the PFU method is suitable for long-term on-line monitoring of trace OCPs in aquatic ecosystems. Therefore, continuous studies monitoring OCPs in lakes and rivers are needed to further understand the future trend of contamination. 相似文献
ABSTRACTThis paper assesses the evolution of generation technology-mix in Australia, with specific emphasis on understanding how such evolution has been shaped by wider political and socio-economic influences. This assessment is predicated on the argument that the contemporary, quintessentially techno-economic, policy discourse on renewable energy is deficient, as it ignores climacteric political and socio-economic influences on generation technology-mix. The methodological framework employed in this paper is informed by the core tenets of technological change theory. The assessment suggests that generation technology-mix in Australia has historically been overwhelmingly influenced by the underlying technological paradigm of the electricity industry; and that this technological paradigm essentially draws its imprimatur from the wider political and socio-economic contexts. By implication, it suggests that a rapid uptake of renewables will have widespread ramifications, extending into political, socio-economic and cultural realms of a society. Clearly, existing policy discourse – that tends to focus on technical potentials, cost competitiveness, externalities and risks of various renewable technologies – is deficient. A much broader discourse is needed. This paper also made an attempt to develop a basis for such a discourse by reviewing broader aspects of the Australian society that would be affected by a rapid uptake of renewables. 相似文献
Russian Journal of Ecology - Temporal and spatial variations of phytoplankton community in Lake Erhai were investigated from May 2010 to April 2011. A total of 124 species belonging to 8 phyla and... 相似文献
Gasification experiments for sawdust were conducted using a fixed bed reactor at 900 °C by varying the secondary oxidant injection ratio to determine the optimal conditions for tar removal along with the enhancement of gasification efficiency. Secondary oxidant was injected as an oxidant at the top zone of the gasifier in varying ratios of 10–30% of the total amount of oxidant. This method was based on the primary method of tar removal and gasification efficiency improvement by thermal cracking of tar. Various gasification performance parameters were evaluated and tar content was estimated by measuring the fluctuation of weight of the activated carbon filter. The results showed that the concentration of tar in the producer gas decreased by injecting the secondary oxidant, even though syngas yield decreased. The recycling potential of the char produced in the gasification experiments was also assessed with the purpose of utilizing char as an adsorbent by determining its surface area and pore volume. The results demonstrated that the char produced from the gasification experiment had similar quality to that of the activated carbon used in this experiment. 相似文献
A major challenge in recycling of silicon powder from kerf loss slurry waste is the complete removal of metal particles. The traditional acid leaching method is costly and not green. In this paper, a novel approach to recover high-purity Si from the kerf loss slurry waste of solar grade silicon was investigated. The metal impurities were removed with superconducting high gradient magnetic separation technology. The effects of process parameters such as magnetic flux density, slurry density, and slurry flow velocity on the removal efficiency were investigated, and the parameters were optimized. In one lot of control experiments, the silicon content was increased from 90.91 to 95.83%, iron content reduced from 3.24 to 0.57%, and aluminum content from 2.44 to 1.51% under the optimum conditions of magnetic flux density of 4.0 T, slurry density of 20 g/L, and slurry flow velocity of 500 mL/min. The result indicates that the superconducting high gradient magnetic separation technology is a feasible purifying method, and the magnetic separation concentrate could be used as an intermediate product for high-purity Si powder.