523 resultados para Yunnan China
Resumo:
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 (GCECD). The concentrations of pp'-DDE, HCB and HCHs were undetectable to 1.86 mu g l(-1) (mean 0.27 mu g l(-1)), undetectable to 0.72 mu g l(-1) (mean 0.11 mu g l(-1)), and 0.24-21.95 mu g l(-1) (mean 7.39 mu g l(-1)) respectively in lakes; and those in rivers were undetectable to 0.23 mu g l(-1) (mean 0.08 mu g l(-1)), 0.68-2.93 mu g l(-1) (mean 1.70 mu g l(-1)), and 2.71-37.56 mu g l(-1) (mean 17.01 mu g l(-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. (c) 2006 Elsevier Ltd. All rights reserved.
Resumo:
The testate amoebae from nine major lakes in the Yunnan Plateau, southwest China were investigated from August to October 2003. Ninety-four species and subspecies belonging to 21 genera were found, and six species were new to the testate amoebae fauna of China. The most diverse genera were Difflugia (28 species), Centropyxis (22 species), Arcella (12 species), and Euglypha (seven species), while the predominant genera were Centropyxis (42.0%), Difflugia (21.4%), Arcella (9.7%), and Euglypha (8.2%). The most diverse testate amoebae fauna was found in a mesotrophic lake, Lake Yilong (57 species). The lowest species richness was recorded in the two hypereutrophic lakes, Lake Dianchi (7 species) and Lake Xingyun (11 species). The results suggest that the lake trophic status plays an important role in shaping community structure and in determining species diversity of testate amoebae.
Resumo:
Garra bispinosa, a new species of cyprinid fish from the Irrawaddy River basin in Yunnan, Southwest China is described here. It has a conspicuous, quadrate and forwards pointed proboscis reflected downwards against the snout and anteriorly bilobed with one large, uniscupid and acanthoid tubercle on the distal end of each lobe, a character unique among all other congeners in Southeast Asia and China, and further differs from them in having the following combination of characters: snout with a deep groove across its tip to form a transverse lobe, 16 circumpeduncular scales, 34-35 lateral line scales, a smaller mental disc (length 38.1-43.8 % of head length), a forwards situated anus (anus to anal distance 25.9-30.6 % of pelvic to anal distance), and a slightly pointed snout.
Resumo:
Fifty-one phytoplankton samples were collected from different ecological environments in five provinces located in the central, eastern and southwestern parts of China. 41 taxa of silica-scaled chrysophytes, 8 of them belonging to the Chrysophyceae and 33 to the Synurophyceae, have been identified by means of electron microscopy. Among them, Mallomonas parvula, M. calceolus, M. cyathellata (?), M. costata, M. crassisquama, and Synura echinulata are new to China. The silica-scaled chrysophyte flora and its geographical distribution in this region are analysed and discussed.
