Toxic effects of chlortetracycline on maize growth, reactive oxygen species generation and the antioxidant response

The toxicity of chlortetracycline (CTC) on maize (Zea mays L.) growth and reactive oxygen species (ROS) generation was studied. The root and shoot lengths and fresh weights of maize seedlings were inhibited by CTC treatment (p < 0.05). Root length was more sensitive than other parameters with the EC₁₀ value of 0.064 mg/L. The spin trapping technique followed by electron paramagnetic resonance (EPR) analysis was used to quantify the ROS production. The ROS generated in maize roots after exposure to CTC was identified as hydroxyl radical (.OH). The EPR signal intensity correlated positively with the logarithm of CTC concentrations exposed (p < 0.05). The dynamic changes of malondialdehyde (MDA) contents and the antioxidative enzyme activities in maize roots were also determined. As compared to the control group, CTC was found to significantly increase MDA content. Treatment of maize roots with the.OH scavenger sodium benzoate (SB) reduced the MDA content and enhanced the antioxidative enzyme activities. The results demonstrated the harmfulness of CTC at high dose to maize in the early developmental stage, and clarified that the inducement of.OH is one of the mechanisms of CTC toxicity.     

Biosorption of Sb (V) by Cyanobacteria from Taihu Lake

利用富营养化湖泊的藻类——太湖蓝藻,对Sb(V)的生物吸附特征进行了研究.结果表明:藻类经0.1 mol/L盐酸处理后,对Sb(V)的生物吸附效率大大提高.原藻和经盐酸处理的蓝藻在1 h左右对Sb(V)的吸附量达到平衡;Sb(V)在原藻和经盐酸处理的蓝藻表面的吸附能力均随着pH升高逐渐减弱;原藻与经盐酸处理的蓝藻对Sb(V)的吸附等温线符合Freundlich方程;不同离子强度的CI-、NO3-、SO42-、PO43-对Sb(V)在原藻表面的吸附影响较弱而对Sb(V)在经盐酸处理的蓝藻表面的吸附影响显著.     

商品氯氰菊酯对斜生栅藻生长的影响及其生理生化效应

研究了商品氯氰菊酯对斜生栅藻(Scenedesmus obliquus)生长及生理生化指标的影响,以了解除虫菊酯农药对水生态系统的影响.在氯氰菊酯暴露下,藻细胞生长受到明显抑制,氯氰菊酯对斜生栅藻生长的72h半效应浓度(EC50)为2.37mg/L.藻细胞所有生理生化指标对氯氰菊酯响应迅速,12h到达最大促进或者抑制效果,48h后趋于平稳.其中12h处理,可溶性糖和可溶性蛋白含量上升,中等浓度组的促进作用最强;超氧化物歧化酶(SOD)活性则呈现出低浓度促进、高浓度抑制效应.氯氰菊酯能促进藻细胞膜脂氧化产物丙二醛(MDA)的产生,且呈现出明显的剂量—效应关系,MDA含量可以作为监测氯氰菊酯污染的生物标记指标之一.研究结果表明,SOD活性抑制以及膜脂氧化是氯氰菊酯对斜生栅藻的重要致毒机理,但自然环境中的氯氰菊酯水平不会对淡水水体浮游藻类的生长产生抑制作用.     

GPS在管线控制测量中的应用

对静态GPS在管线控制测量中的应用做了阐述,包括选点、数据采集和数据处理,结合GPS自带的后处理软件,以实例介绍了在数据处理中遇到的问题和解决方法.     

撒哈拉大沙漠的气象灾害

<正>独一无二的大沙漠撒哈拉大沙漠位于北部非洲的阿特拉斯山脉和地中海以南,250毫米等雨线(约北纬14°线)以北;西起大西洋海岸,东临红海的广阔地区,是世界上最大的沙漠。"撒哈拉"是阿拉伯语中"大荒漠"一词的音译。     

Towards sustainable community‐based natural resource management in the indigenous Meqmegi community in Taiwan: Rethinking impacts of local participation

This paper examines approaches for local resident participation in community‐based natural resource management (CBNRM); focusing particularly on the potential impacts that local participation imposes on the natural environment. This study used qualitative methods to collect data, and selected Meqmegi, an indigenous community in Taiwan, as a case study. The findings indicate that many opportunities can be created that stimulate a community to participate in natural resource management; moreover, residents are prone to use their own ways to participate. Therefore, although local participation is praised for its people‐oriented way of natural resource management, impacts from the participation process will ultimately be imposed on the environment. We suggest that more consideration be given to the environmental conditions during the process of local participation via CBNRM to make sure that impacts on the environment are positive, and lead to a truly sustainable future.     

The metabolism of neonicotinoid insecticide thiamethoxam by soil enrichment cultures,and the bacterial diversity and plant growth‐promoting properties of the cultured isolates

A soil enrichment culture (SEC) rapidly degraded 96% of 200 mg L^?1 neonicotinoid insecticide thiamethoxam (TMX) in MSM broth within 30 d; therefore, its metabolic pathway of TMX, bacterial diversity and plant growth‐promoting rhizobacteria (PGPR) activities of the cultured isolates were studied. The SEC transformed TMX via the nitro reduction pathway to form nitrso, urea metabolites and via cleavage of the oxadiazine cycle to form a new metabolite, hydroxyl CLO‐tri. In addition, 16S rRNA gene‐denaturing gradient gel electrophoresis analysis revealed that uncultured rhizobacteria are predominant in the SEC broth and that 77.8% of the identified bacteria belonged to uncultured bacteria. A total of 31 cultured bacterial strains including six genera (Achromobacter, Agromyces, Ensifer, Mesorhizobium, Microbacterium and Pseudoxanthomonas) were isolated from the SEC broth. The 12 strains of Ensifer adhaerens have the ability to degrade TMX. All six selected bacteria showed PGPR activities. E. adhaerens TMX‐23 and Agromyces mediolanus TMX‐25 produced indole‐3‐acetic acid, whereas E. adhaerens TMX‐23 and Mesorhizobium alhagi TMX‐36 are N₂‐fixing bacteria. The six‐isolated microbes were tolerant to 200 mg L^?1 TMX, and the growth of E. adhaerens was significantly enhanced by TMX, whereas that of Achromobacter sp. TMX‐5 and Microbacterium sp.TMX‐6 were enhanced slightly. The present study will help to explain the fate of TMX in the environment and its microbial degradation mechanism, as well as to facilitate future investigations of the mechanism through which TMX enhances plant vigor.     

也给它们留个家园

2010年上海世博会虽近尾声,但＂城市,让生活更美好＂这一主题却深入人心。在今后的几十年里,城市化将一直是中国发展的主要途径,而城市化发展的宗旨应该始终是＂让生活更美好＂。怎样的城市才能＂让生活更美好＂呢？当然是节能、低碳、可持续发展的城市,2010年上海世博会已经把这个主题诠释得十分明白清晰。加强节能减排、实现低碳生活,归根结底是为了保护生态环境,     

传统的“低碳”节能建筑

<正>建筑节能"今不如昔"中华民族历来有以家为中心的传统。无论是平民百姓"老婆、孩子、热炕头"的生活目标,还是社会精英"欲治其国者,先齐其家"的雄心壮志,都是以家为基础的。家又必须存在于能挡风遮雨、避暑御寒的住宅之内,由此可见住宅对于中国人来说是何等的重要。无怪乎,房价能够     

赤泥在控制沉积物磷释放中的应用研究

利用烧结法赤泥中富含Ca、Fe等金属元素的氧化物而具有吸附性的特点,通过室内模拟研究赤泥投加对沉积物中各种磷形态含量及分布比例的影响,进而探讨利用赤泥控制沉积物中磷释放的可行性。对经过处理后的沉积物磷形态分析后表明,投加赤泥能促使沉积物中铁铝磷向钙磷转化（Pearson相关分析,r=-0.892,P<0.01,n=9）,且赤泥的强碱性使沉积物pH值逐渐升高。确定了赤泥最佳投加比例为5%,此时沉积物的pH为9.03,铁铝磷含量由初始的148 mg/kg降至107 mg/kg,占总磷比例也由18.1%降至13.4%,钙磷含量由486 mg/kg升至546 mg/kg,其占总磷比例则由60%增至68.7%,铁铝磷和钙磷之间的转化已基本完成,继续增加赤泥投加量对沉积物中磷形态间的相互转化影响甚微。由于铁铝磷较钙磷活性高而易释放,可见投加赤泥能降低沉积物中磷的释放风险。赤泥可以作为吸附材料被应用于沉积物磷污染控制技术中,为有效控制水体内源磷负荷提供一种新思路和廉价材料。