Poplar plantation has the potential to alter the water balance in semiarid Inner Mongolia

Poplar plantation is the most dominant broadleaf forest type in northern China. Since the mid-1990s plantation was intensified to combat desertification along China's northwestern border, i.e., within Inner Mongolia (IM). This evoked much concern regarding the ecological and environmental effects on areas that naturally grow grass or shrub vegetation. To highlight potential consequences of large-scale poplar plantations on the water budget within semiarid IM, we compared the growing season water balance (evapotranspiration (ET) and precipitation (PPT)) of a 3-yr old poplar plantation (Kp₃) and a natural shrubland (Ks) in the Kubuqi Desert in western IM, and a 6-yr old poplar plantation (Bp₆) growing under sub-humid climate near Beijing. The results showed that, despite 33% lower PPT at Kp₃, ET was 2% higher at Kp₃ (228 mm) as compared with Ks (223 mm) in May–September 2006. The difference derived mainly from higher ET at the plantation during drier periods of the growing season, which also indicated that the poplars must have partly transpired groundwater. Estimated growing season ET at Bp₆ was about 550 mm and more than 100% higher than at Kp₃. It is estimated that increases in leaf area index and net radiation at Kp₃ provide future potential for the poplars in Kubuqi to exceed the present ET and ET of the natural shrubland by 100–200%. These increases in ET are only possible through the permanent use of groundwater either directly by the trees or through increased irrigation. This may significantly change the water balance in the area (e.g., high ET at the cost of a reduction in the water table), which renders large-scale plantations a questionable tool in sustainable arid-land management.     

锅炉量化管理是企业挖潜节能的重要途径

通过对辽河油田公司有关企业开展清洁生产审核,总结出了燃料锅炉量化管理的方法。在自然对流烘干室改造、碱液浓缩炉改造、燃煤锅炉设计效率核准等实例中,该方法可昭示能耗大的"瓶颈"部位,进而为企业制定节能方案、提出具体的节能改造措施提供了科学依据。实践证明:实施锅炉量化管理是企业挖掘节能潜力的重要途径。     

花生壳提取物的体外抗氧化活性研究

为研究花生壳提取物的体外抗氧化活性,测定了花生壳提取物的还原能力、抗脂质过氧化作用、抑制油脂过氧化作用以及清除超氧阴离子自由基、羟基自由基、DPPH自由基的能力,并与抗坏血酸进行了比较.结果表明,花生壳提取物具有较好的总抗氧化活性和总还原性,能抑制脂质过氧化和油脂过氧化作用以及清除自由基.它对DPPH自由基、羟基自由基、超氧阴离子自由基的IC50分别为27.82μg/ml、183μg/ml、89μg/ml.研究表明,花生壳提取物具有较强的综合抗氧化能力,是一种很有开发价值的天然抗氧化剂.     

鲤鱼鱼鳃微环境酸碱条件与铜形态分布模拟

用鱼鳃微环境测定装置和化学平衡计算方法,研究了在人工河水中暴露于铜的鲤鱼鳃部微环境的pH、碱度、粘液含量和铜形态分布.结果发现,鱼鳃pH平衡点为6.92,人工河水pH高于或低于此值时,鱼鳃微环境pH偏低或偏高.变化幅度约达-0.6至0.4 个pH单位.根据实测结果分别建立了计算人工河水和鱼鳃微环境碱度以及鱼鳃粘液分泌量随暴露铜含量和pH变化的定量模型.化学平衡计算结果说明,在pH6至9范围内,人工河水中优势态铜从游离态铜过渡到羟基络合态铜.由于粘液和pH差异的影响,鱼鳃微环境中生物有效态铜含量显著低于人工河水.这样的差别在酸性条件下尤为显著.     

Changes in male guppy courting distance in response to a fluctuating light environment

In the guppy (Poecilia reticulata), effective courting by a male requires visual contact with the female. Therefore, environmental light intensity may affect male display behavior, particularly initial courtship distance. We found that male guppies courted at exact and predictable distances from the female given a particular light level, both in field and laboratory studies. In lower light levels (<0.1 μmol m⁻² s⁻¹), for example at dawn, dusk, or under heavy canopy, males court females at closer and less variable distances (<3 cm). At higher light levels, which occur during most of the day and with less canopy cover, males often court from twice or three times further out. Light levels over guppy streams change over relatively short time periods and ranges, correlating with variation in courtship distances. Laboratory manipulations of irradiance confirmed that courtship distance depends on illumination. Hence, courtship distances may be set by the effect of lighting on signal efficiency, minimization of energy or time expenditures, or predation risk. Received: 16 December 1997 / Accepted after revision: 8 August 1998     

Metallic and organic contaminants in sediments of Sydney Harbour, Australia and vicinity-- a chemical dataset for evaluating sediment quality guidelines

An internally consistent dataset comprising 103 surficial estuarine sediment samples were collected from Sydney Harbour, Australia and locations south of Sydney. This paper describes the chemical characteristics of the dataset and evaluates its suitability for use in evaluating biological effects-based sediment quality guidelines (SQGs). The sediments contained mixtures of chemicals, the most prevalent chemical classes being metals and polycyclic aromatic hydrocarbons, whereas sediments from coastal lakes/estuaries south of Sydney had low concentrations of contaminants. Maximum concentrations of the prevalent contaminants zinc, lead, copper and pyrene were 11,300, 1,420, 1,060 mg kg(-1) and 23,300 microg kg(-1), respectively. For the majority of samples, concentrations of individual chemicals exceeded most effects-based SQGs that have been adopted for use in Australia, implying occasional or frequent adverse biological effects are expected. Comparing mixtures of contaminants to ranges in numbers of SQGs exceeded and mean SQG quotients showed that most samples (57% to 68%) had contamination characteristics associated with moderate probabilities (30% to 52%) of acute toxicity, based on North American data. A smaller proportion of samples (15% to 17%) had contamination characteristics associated with high probabilities (74% to 85%) of toxicity. The wide range of chemicals and concentrations, associated with low, medium and high probabilities of toxicity, indicated that the dataset was suitable for future use in evaluating predictive abilities of SQGs. This is relevant, given the recent introduction of North American-derived SQGs for Australia.     

江苏近岸海域富营养化特征研究

近年来,江苏近岸海域水质不佳,赤潮、绿潮等生态灾害屡屡发生,富营养化是其潜在原因之一。本文对该海域2019年和2020年春、夏、秋季航次监测的无机氮（DIN）、活性磷酸盐（SRP）、叶绿素a(Chl a)等水质参数进行了空间分析,采用指数评价法量化了该海域的富营养化程度,并基于统计分析研究了该海域的富营养化特征。结果表明：江苏近岸海域DIN浓度和SRP浓度总体呈现近岸高、远岸低的分布特征,营养盐浓度与盐度呈显著负相关关系;在降水量和径流量更大的夏季,营养盐浓度和Chl a浓度比春季和秋季更高;丰水年（2020年）相较平水年（2019年）,该海域的氮磷比和富营养化程度均更高。因此,陆源输入对江苏近岸海域的富营养化程度有至关重要的影响,加强对入海河流的监测和排污治理是缓解该海域富营养化的关键。     

新型侧向流曝气生物滤池处理生活污水

采用以沸石为填料的新型侧向流曝气生物滤池处理生活污水,考察了水力负荷和气水比的影响.结果表明,LBAF在最佳工况气水比10∶1,A、B段曝气量比1∶1,水力负荷0.43 m3/m2·h下,COD、SS、氨氮、总氮和总磷的去除率分别为88.01%、95.18%、78.97%、52.58%和21.02%;COD去除率随COD容积负荷的增加缓慢下降.氨氮、总氮去除率随COD容积负荷的增大明显下降,氨氮去除率随氨氮容积负荷的增大而明显降低.滤池纳污能力强,不易堵塞,可适当延长反冲周期.     

Carrousel氧化沟单个表曝机流态的模型试验和分析比较

对仅安装1个倒伞形表面曝气机(简称表曝机)的Carrousel氧化沟模型进行了水力学测定,通过颗粒动态分析仪(PDA)系统分析流出和流入表曝机一侧的液体流动速度、沉降速度,以及固体含量分布.结果表明,流出表曝机一侧,距表曝机较近的x轴位置流速较大;沉降速度沿y轴有个转折点,位于沟壁与挡板的中间;远离单个表曝机,固体含量逐渐增大.并将单个表曝机的测量结果与氧化沟内安装2个表曝机的流动试验进行比较,发现2个表曝机所产生的流场与单个表曝机产生的流场差别较大,且2个表曝机所产生的流场更稳定.      

道路车辆-供电电压42V的电气和电子装备电源环境 ISO 21848:2005 IDT

1 范围 本标准描述了可以影响由单42V或组合42V电气系统供电的道路车辆的电气和电子系统及组件的电源环境.