不同利用方式对江西省农田土壤碳氮磷生态化学计量特征的影响

根据江西省2013年采集的16582个农田耕层(0～20 cm)土壤样点数据,运用实地调查、经典统计学与地统计学等相结合方法,研究了江西省耕地土壤碳氮磷生态化学计量特征的空间变异性及不同农田利用方式对其的影响.研究结果表明:江西省耕地土壤有机碳(SOC)、全氮(TN)和全磷(TP)平均含量分别为17.90、1.58和0.52 g·kg~(-1),土壤碳氮比(C∶N)、碳磷比(C∶P)和氮磷比(N∶P)平均值分别为11.72、38.29和3.38,土壤C∶N∶P比平均值为34.44∶3.03∶1,说明P是江西省耕地土壤主要的限制因素.此外,由于碳、氮、磷三者之间并不存在显著的两两相关性,表明江西省耕地土壤中不存在稳定的"Redfield ratio";半方差函数表明,江西省土壤碳、氮、磷生态化学计量特征具有中等程度的空间变异性,其空间变异特征主要受到随机性因素的影响;经ANOVA检验显示,不同农田利用方式对土壤碳氮磷生态化学计量特征影响显著(p0.05),土壤SOC和TN平均含量依次表现为:两季水田水旱轮作一季水田一季旱地两季旱地,土壤TP平均含量依次表现为:两季旱地两季水田一季水田一季旱地水旱轮作,土壤C∶N依次表现为:两季水田两季旱地一季水田水旱轮作一季旱地,土壤C∶P平均值依次表现为:水旱轮作两季水田一季水田一季旱地两季旱地,土壤N∶P平均值依次表现为:水旱轮作一季旱地两季水田一季水田两季旱地.总体而言,土壤碳、氮、磷生态化学计量比的变化特征是农田利用方式和环境因子综合作用的结果,土壤C∶N∶P比对土壤碳、氮、磷储量及养分的限制性具有重要的指示作用.     

我经历的松潘-平武地震

1976年8月16日和23日,四川松潘平武地区连续发生了两次Ms7．2的强烈地震。作为地震监测人员,我参加了这次地震前后的一些工作。在松潘一平武地震30周年之际,将当时参加地震监测时的所见所闻再现,以示纪念。     

Bracketing team boundary spanning: An examination of task‐based,team‐level,and contextual antecedents

There is growing recognition that teams do not function in a vacuum and that external boundary activities are important predictors of team performance, effectiveness, and knowledge sharing. In the past, researchers have focused on the effects of team composition or task characteristics as antecedents of critical boundary spanning activities. However, less effort has been directed at understanding how antecedents at multiple levels can simultaneously influence boundary spanning behavior in teams. This paper takes stock of over 20 years of research on the topic of team boundary spanning. Adopting a “bracketing” approach etc., we develop a multi‐level theoretical model to guide future research on the determinants of team boundary spanning. This model specifies task‐based, team‐level, and contextual antecedents of team boundary spanning and outlines the contingencies shaping the emergence of effective boundary‐management behavior in teams. Copyright © 2008 John Wiley & Sons, Ltd.     

Spatial distribution and seasonal variation of char-EC and soot-EC in the atmosphere over China

A previous study on PM_2.5 carbonaceous aerosols measured with the thermal optical reflectance (TOR) method in fourteen Chinese cities is extended by subdividing total EC into char-EC and soot-EC. Average char-EC concentrations show great differences between the fourteen cities and between winter and summer periods, with concentrations of 8.67 and 2.41 μg m^?3 in winter and summer, respectively. Meanwhile spatial and seasonal soot-EC variations are small, with average concentrations of 1.26 and 1.21 μg m^?3 in winter and summer, respectively. Spatial and temporal distributions of char-EC, similar to EC, are mainly influenced by local fuel consumption, as well as the East Asian monsoon and some meteorological factors such as the mixing height and wet precipitation. The small spatial and seasonal variation of soot-EC is consistent with its regional-to-global dispersion, which may suggest that soot carbon is not local carbon, but regional carbon. Char-EC/soot-EC ratios show summer minimum and winter maximum in all cities, which is in good agreement with the difference in source contributions between the two periods. As OC/EC ratio is affected by the formation of the secondary organic aerosol (SOA), char-EC/soot-EC ratio is a more effective indicator for source identification of carbonaceous aerosol than previously used OC/EC ratio.     

镉胁迫对向日葵幼苗生长和生理特性的影响

采用溶液培养方法,研究了不同浓度镉(0、0.05、0.1、0.5和1 mg/L)处理7 d对向日葵幼苗生长和生理特性的影响。结果表明：随着镉处理浓度的增加,向日葵幼苗对镉的吸收显著增加。1 mg/L镉浓度处理时,叶、茎和根中镉浓度分别为0.05 mg/L镉处理时的16.3、19.2和581倍;根中积累的镉含量明显高于叶和茎, 各浓度根部积累的镉分别为叶和茎的37.8～63倍和29.4～41倍。镉胁迫显著抑制向日葵幼苗生长和叶绿素合成,当镉浓度达1 mg/L时,整株植物生物量和总叶绿素含量分别为对照的55.9%和52.6%。镉胁迫下向日葵幼苗游离脯氨酸和丙二醛（MDA）含量显著增加,1 mg/L镉浓度时,根中含量分别为对照的4和5.8倍。向日葵幼苗可溶性蛋白含量和过氧化物酶(POD)活性变化与镉胁迫浓度呈明显的倒U字型关系,可溶性蛋白含量在0.05 mg/L镉浓度时达到最大值,叶、茎、根中的POD活性分别在0.1、0.1和0.05 mg/L镉浓度时达到最大值。     

Analysis of Coupling between Soil and Water Conservation and Economic-social Development

The coupling relation exists in water and soil conservation and economic-social development. The article analyses the relation of soil and water conservation and economic-social development stages as well as the coupling analytical method. Then calculates the expecting income by dispersing Markov decision and calculates the correlation coefficient and the relationship degree. The article obtains the relationship of soil and water conservation investments and all kinds of incomes. Finally, it analyzes the important meaning in socio-economic development of water and soil conservation.     

Levels and congener profiles of PCDD/Fs, PCBs and PBDEs in seafood from China

A nationwide investigation into polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) in market seafood was conducted for the first time in this study. Total PCDD/F concentrations in fatty fish ranged from 0.13 to 8.64 pg g⁻¹ wet weight (mean 2.05 pg g⁻¹ wet weight), total PCB concentrations ranged from 38.9 to 3514 pg g⁻¹ wet weight (mean 1133 pg g⁻¹ wet weight), and total PBDE concentrations ranged from 42.8 to 913 pg g⁻¹ wet weight (mean 322 pg g⁻¹ wet weight). Corresponding mean toxicity equivalent (TEQ) values for total PCDD/F and dioxin-like PCB were 0.25 pg g⁻¹ wet weight (WHO 98-TEQ) and 0.32 pg g⁻¹ wet weight (WHO 98-TEQ), respectively. OCDD, PCB-138 and PBDE-47 were the dominant compounds according to their respective congeners. WHO 98-TEQ _{PCDD/PCDF/PCB} for fatty fish and shell fish were 0.60 and 0.070 pg g⁻¹ wet weight, respectively, lower than the standard set by the European Commission. The contamination levels and profiles were compared with those documented in previous publications.     

生活垃圾卫生填埋场甲烷减排与控制技术研究

系统地研究了生物氧化、生物抑制和风力驱动准好氧填埋的生活垃圾卫生填埋场甲烷减排集成技术.研究表明,喷洒了NMS营养液(80 mL/kg)的矿化垃圾为甲烷氧化覆盖层,可以持续氧化甲烷,第23天后甲烷氧化率稳定在75%左右;当氯仿质量浓度为20 mg/kg或乙炔体积分数达到1.2%时,甲烷产量极少,产甲烷菌几乎被完全抑制;采用风帽技术的改进型准好氧填埋可以利用风速0.5 m/s的自然风,在不增加成本的前提下大幅减少甲烷排放.     

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.