What Do the Occurrences of Migratory Fishes in the Upper Mekong Mean?

This paper examines the recent appearance of four migratory species in the Upper Mekong: Dasyatis laosensis, Anguilla bicolor, Anguilla marmorata, and Chitala ornata. Since 2006 these species have been continually sampled in an area below Jinghong Dam in Xishuangbanna, China. This region is far beyond their historical upstream distribution, and the reasons for these appearances and their subsequent impact on river ecosystem are considered.     

Can conservation of single surrogate species protect co-occurring species?

Conservation of surrogate species is expected to benefit co-occurring species with similar distributions that share the same habitat, yet the usefulness of this approach to protect nontarget species has been extensively challenged. In this study, we aimed to assess whether co-occurring species could be afforded protection under the conservation of two proposed surrogate species, the giant panda and the takin. We undertook a thorough study on the habitat requirements of these two endangered species, based on the analysis of their habitat preferences. The results revealed that the giant panda exhibits more specialized habitat preferences than does the takin and that habitat separation between these species mainly reflected differences in their dietary requirements and preferences. We suggest that these differences might facilitate their coexistence in sympatric areas. Meanwhile, results of a discriminant function analysis showed that protection of giant pandas would protect 82.1 % of the panda’s habitat, but only 25.4 % of the takin’s habitat and just 57.0 % of the joint habitats of these species. Importantly, our results also showed that a joint surrogate species approach to conservation would protect 86.9 % of the panda’s habitat, 53.7 % of the takin’s habitat, and 72.2 % of the joint habitats of these species. This is a higher degree of habitat protection than the single surrogate conservation of pandas. We conclude that the joint surrogate species approach should be adopted to improve biodiversity conservation.     

Polycyclic aromatic hydrocarbons in bulk PM2.5 and size-segregated aerosol particle samples measured in an urban environment

To analyze polycyclic aromatic hydrocarbons (PAHs) at an urban site in Seoul, South Korea, 24-hr ambient air PM_2.5 samples were collected during five intensive sampling periods between November 1998 and December 1999. To determine the PAH size distribution, 3-day size-segregated aerosol samples were also collected in December 1999. Concentrations of the 16 PAHs in the PM_2.5 particles ranged from 3.9 to 119.9 ng m⁻³ with a mean of 24.3 ng m⁻³.An exceptionally high concentration of PAHs(∼120 ng m⁻³) observed during a haze event in December 1999 was likely influenced more by diesel vehicle exhaust than by gasoline exhaust, as well as air stagnation, as evidenced by the low carbon monoxide/elemental carbon (CO/EC) ratio of 205 found in this study and results reported by previous studies. The total PAHs associated with the size-segregated particles showed unimodal distributions. Compared to the unimodal size distributions of PAHs with modal peaks at < 0.12 μm measured in highway tunnels in Los Angeles (Venkataraman and Friedlander, 1994), four- to six-ring PAHs in our study had unimodal size distributions, peaking at the larger size range of 0.28–0.53 μm, suggesting the coagulation of freshly emitted ultrafine particles during transport to the sampling site. Further, the fraction of PAHs associated with coarse particles(> 1.8 μm) increased as the molecular weight of the PAHs decreased due to volatilization of fine particles followed by condensation onto coarse particles.     

养分(磷)吸收机理模型的应用研究──Ⅱ.模型参数的敏感性分析

采用Claassen的养分吸收机理模型探讨了玉米与大豆幼苗磷吸收过程中的参数敏感性,结果表明：在一般土壤与施肥条件下,玉米与大豆幼苗吸收磷的高度敏感性参数或重要限制因素为根系伸长速率与根半径;在相同土壤供磷条件下,供试大豆幼苗根系的磷摄取能力远低于玉米幼苗根系的磷摄取能力,其原因归结于两者在根系最大养分流Imax与根系伸长速率K两个敏感性参数上的差异;玉米与大豆幼苗磷吸收过程中三种根毛参数的敏感性均较低,这主要与土壤供磷水平较高有关;土壤含水量在玉米幼苗磷吸收过程中表现了极高的敏感性,当土壤含水量降低时,土壤养分供应参数对玉米幼苗磷吸收的敏感性与限制作用均增大。     

Occurrence and distribution of antibiotics in coastal water of the Taizhou Bay,China: impacts of industrial activities and marine aquaculture

Environmental Science and Pollution Research - The occurrence, spatial distribution, and source analysis of antibiotics in global coastal waters and estuaries are not well documented or understood....     

Impact of aquaculture on distribution of dissolved organic matter in coastal Jeju Island,Korea, based on absorption and fluorescence spectroscopy

Environmental Science and Pollution Research - In Jeju Island, multiple land-based aquafarms were fully operational along most coastal region. However, the effect of effluent on distribution and...     

大件车作用下独柱墩弯桥倾覆风险快速预测∗

为了实现大件运输车辆作用下独柱墩弯桥倾覆风险的快速预测,首先对基于刚体转动理论的简化计算方法进行改进,引入车辆转弯模型考虑车轮轨迹,实现车辆荷载的准确和快速加载,定义了稳定因子η 并提出质心加载法用于确定倾覆轴线;结合变形体理论,提出采用端点偏移的方法对倾覆轴位置进行修正;采用阈值法快速评价桥梁的倾覆风险性,并通过建立ABAQUS 实体模型分析了大量桥梁的倾覆过程,确定阈值[kc]的取值;在此基础上建立了独柱墩弯桥倾覆风险快速预测流程。研究结果表明：大件车以稳定状态通过弯桥时其质心轨迹为一圆弧;对倾覆轴线位置进行修正可以考虑主梁变形能力对稳定效应的削减,相比于原简化方法,由改进方法计算的抗倾覆稳定能力kc 对桥梁的倾覆风险具有更强的表征能力;抗倾覆稳定能力阈值取值为1.10;基于MATLAB 程序语言,编制了弯桥倾覆风险快速预测程序,通过批量输入大件车待通行线路上的独柱墩弯桥信息即可计算出各个桥梁的抗倾覆稳定能力kc,将kc与抗倾覆能力阈值进行比较从而预测出有倾覆风险的桥梁,实现大件车作用下独柱墩弯倾覆风险快速预测。     

Research on optimal control of non-point source pollution: a case study from the Danjiang River basin in China

Environmental Science and Pollution Research - The impact and optimal control of non-point source (NPS) pollution on water environment have become the hot issues of current research. This paper...     

Nano-TiO2 Modified Wheat Straw/Polylactic Acid Composites Based on Synergistic Effect Between Interfacial Bridging and Heterogeneous Nucleation

Journal of Polymers and the Environment - To improve the interfacial compatibility of wheat straw/polylactic acid (WS/PLA) composites, nano-TiO2 with different particle sizes was blended with...     

Design a flower-like magnetic graphite carbon microsphere for enhanced adsorption of 2,4-dichlorophenol

Environmental Science and Pollution Research - 2,4-Dichlorophenol (2,4-DCP) is a hazardous chlorinated organic chemical, so its removal is an important task to protect the whole ecosystem and human...