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511.
长江八里江江段是长江江豚最为重要的栖息地之一。2005年7月至2008年5月,在八里江江段先后进行了10次截线抽样法考察,调查了该水域的江豚种群数量和分布情况。考察总航程1 460.2 km,发现江豚374群次。根据动物密度,将考察区域划分为上游水域(九江 湖口)和下游水域(湖口 三号洲洲头),分别分析。分析结果显示,上下游水域的多次考察密度平均值分别为0.67头/km2(范围:0.10~1.28头/km2,〖WTBX〗s〖WTBZ〗=0.41)和1.75头/km2(范围:0.62~3.0头/km2,〖WTBX〗s〖WTBZ〗=0.72),数量平均值分别37头(范围:5~71头,〖WTBX〗s 〖WTBZ〗=23)和52头(范围:22~78头,〖WTBX〗s 〖WTBZ〗=17)。八里江江段江豚常年平均数量约为90头,不同考察季节数量有所波动(范围:44~121头,〖WTBX〗s 〖WTBZ〗=24)。与历史考察对比分析显示八里江江段江豚仍处于下降趋势,但该研究未能在3年考察期内监测到统计学意义的种群变动情况。根据动物数量波动幅度和发生时间推测,江豚在汛期至汛末的过渡时期,可能存在一次规模为40头左右的动物迁出过程。面对日益严重的人类威胁,如挖沙、非法渔业、航运、污染和水面设施建设等,建议在该江段尽快建立江豚自然保护区 相似文献
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This study investigated the effects of sediment dewatering on the phosphorus transformations concerning about the production and emission of phosphine in the intertidal marsh of the Yangtze Estuary. The concentrations of matrix-bound phosphine ranged from 18.62-72.53 ng kg−1 and 31.14-61.22 ng kg−1 within the August and January exposure incubations, respectively. The responses of matrix-bound phosphine concentrations to sediment dessication demonstrate that the production (or accumulation) of matrix-bound phosphine significantly increased with water loss at the start of the emersion incubations. However, further dehydration inhibited the formation of matrix-bound phosphine in sediments. The significant correlations of matrix-bound phosphine with the organic-P bacteria abundance and alkaline phosphatase activities implicate that the production of matrix-bound phosphine within the dessication incubations was linked closely to the microbial decomposition of organic P. The emissions of phosphine generally decreased with sediment dewatering, with the fluxes of 7.51-96.73 ng m−2 h−1 and 5.34-77.74 ng m−2 h−1 over the exposure incubations of both August and January, respectively. Also, it is observed that the releases of phosphine during the entire exposure periods were affected not only by its production but also by sediment water and redox conditions. 相似文献
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As a new threat to environment all through the world, perchlorate (ClO(4)(-)) was predominantly a thyrotoxin, and its toxic manifestations in non-thyroid were also documented. However, little is known about the effects of ClO(4)(-) on cell and organelle. Therefore, the present study was designed to investigate the effects of ClO(4)(-) on hepatocytes and mitochondria isolated from Carassius auratus from the direct viewpoint of energy by using the microcalorimetric method. The metabolic thermogenic curves of hepatocytes and mitochondria at 25°C were obtained. And the thermokinetic parameters, such as growth rate constant (k), inhibitory ratio (I), maximum thermal power (P(max)) and total thermal effect (Q(total)) have been calculated. The results indicated that the toxicity of ClO(4)(-) on hepatocytes was relevant to the concentration of ClO(4)(-). However, 10-100mgL(-1)ClO(4)(-) stimulated the metabolic activity of mitochondria and the toxicity of ClO(4)(-) on mitochondria only occurrenced when treated with higher concentration of ClO(4)(-). This study shown that mitochondria has a major impact on the metabolic thermogenic of hepatocytes, but not the only factor. Meanwhile, it demonstrated that microcalorimetry was a powerful tool for understanding biological processes and studying on the toxic action of environmental contaminants in cell or subcellular level. 相似文献
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An empirical investigation of construction and demolition waste generation rates in Shenzhen city, South China 总被引:1,自引:0,他引:1
The construction and demolition waste generation rates (C&D WGRs) is an important factor in decision-making and management of material waste in any construction site. The present study investigated WGRs by conducting on-site waste sorting and weighing in four ongoing construction projects in Shenzhen city of South China. The results revealed that WGRs ranged from 3.275 to 8.791 kg/m2 and miscellaneous waste, timber for formwork and falsework, and concrete were the three largest components amongst the generated waste. Based on the WGRs derived from the research, the paper also discussed the main causes of waste in the construction industry and attempted to connect waste generation with specific construction practices. It was recommended that measures mainly including performing waste sorting at source, employing skilful workers, uploading and storing materials properly, promoting waste management capacity, replacing current timber formwork with metal formwork and launching an incentive reward program to encourage waste reduction could be potential solutions to reducing current WGRs in Shenzhen. Although these results were derived from a relatively small sample and so cannot justifiably be generalized, they do however add to the body of knowledge that is currently available for understanding the status of the art of C&D waste management in China. 相似文献
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