Leaf metabolic influence of glyphosate and nanotubes on the Arabidopsis thaliana phyllosphere

Chemical exposure can indirectly affect leaf microbiota communities, but the mechanism driving this phenomenon remains largely unknown. Results revealed that the co-exposure of glyphosate and multi-carbon nanotubes (CNTs) caused a synergistic inhibitory effect on the growth and metabolism of Arabidopsis thaliana shoots. However, only a slight inhibitory effect was induced by nanotubes or glyphosate alone at the tested concentrations. Several intermediate metabolites of nitrogen metabolism and fatty acid synthesis pathways were upregulated under the combined treatment, which increased the amount of energy required to alleviate the disruption caused by the combined treatment. Additionally, compared with the two individual treatments, the glyphosate/nanotube combination treatment induced greater fluctuations in the phyllosphere bacterial community members with low abundance (relative abundance (RA) <1%) at both the family and genus levels, and among these bacteria some plant growth promotion and nutrient supplement related bacteria were markable increased. Strikingly, strong correlations between phyllosphere bacterial diversity and metabolites suggested a potential role of leaf metabolism, particularly nitrogen and carbohydrate metabolism, in restricting the range of leaf microbial taxa. These correlations between phyllosphere bacterial diversity and leaf metabolism will improve our understanding of plant-microbe interactions and the extent of their drivers of variation and the underlying causes of variability in bacterial community composition.     

吉林省辉发河底泥重金属污染评价

辉发河为第二松花江的第一大支流,其污染情况对第二松花江和松花湖的环境影响较大.本文以辉发河底泥为研究对象,测定了底泥中砷、镉、铬、铜、汞、铅和锌等重金属元素含量,探讨了重金属元素分布特点,并采用沉积物基准法和地质累积指数法对重金属污染情况进行了评价.结果表明,辉发河底泥砷、镉、铬、铜、汞、铅和锌平均含量分别为5.9、0.162、71.1、17.6、0.037、21.5 mg/kg和53.3 mg/kg,含量水平比较低,各重金属元素在辉发河干流底泥中含量变化规律基本一致;综合两种污染评价方法结果可知,辉发河底泥中重金属总体污染水平较低,污染元素主要为Cr、Pb、Hg和As.     

共代谢在难生物降解污水处理中的应用

本文简介生物共代谢机理及工程应用的实例,生活污水的共代谢效率可使难生物降解工业污水CODCr去除率提升21.5％,而葡萄糖的共代谢效率可使CODCr去除率提升38.5％,具有明显的降解效果。     

淹水与湿润水分前处理对旱地酸性土壤氧化亚氮和二氧化碳排放的影响

田间采集含水量为21.6%土壤最大田间持水量（Water holding capacity,WHC）的新鲜旱地红砂土,室温下分别进行湿润（土样M,调节含水量为40%WHC）和淹水（土样F）两种水分前处理,保存110d后,将土样M和土样F的含水量再分别调至40%、70%和100%WHC,在25℃下培育120h,设置不通和...     

白腐真菌菌丝球形成的物化条件及其对铅的吸附

为了探讨影响微生物菌丝球生长的物理化学因素和控制菌丝球大小的规律以及微生物吸附重金属的效果,对黄孢展齿革菌（Ｐｈａｎｅｒｏｃｈａｅｔｅｃｈｒｙｓｏｓｐｏｒｉｕｍ）呈球状体生长和用此菌丝球吸附水溶液中的Ｐｂ＾２＋进行了研究。     

常州市典型工业废水综合急性毒性评估

以不同营养级别的藻(生产者)、溞(消费者)和发光细菌(分解者)为指示生物,在发光细菌急性毒性、大型溞急性毒性和叶绿素荧光急性毒性实验这三者的基础上,采用毒性分级体系(toxicity classification system)对常州市六种典型企业原水和处理出水的综合急性毒性进行了评估及比较。结果表明,六种典型企业原水都具有明显的急性毒性,电镀厂、食品厂和综合污水处理厂的处理出水基本无毒,毒性削减明显,但化工厂、印染厂和电子厂处理出水具有较高的急性毒性,而理化指标监测结果表明这六种处理出水可以直接排放。废水综合急性毒性大小和理化指标结果没有必然联系,应进一步完善理化监测指标,强制性增加生物毒性指标的监测。     

利用EDTA溶液淋洗修复重金属污染土壤

通过室内模拟实验,采用振荡淋洗的方法研究了不同浓度、pH值、淋洗时间的EDTA溶液对污染土壤中Ph、Cu、Ni、Zn、Cr的去除,并利用一级反应动力学模型对实验数据进行拟合。结果表明：在实验条件下,EDTA为0．05mol／L、pH值=7、液土比为10：1、淋洗时间为18h的条件下能达到对污染土壤重金属最大去除率,去除率分别为zn85．26％、Cu21．65％、Pb16．76％、Ni7．83％、Cr6．29％。模型拟合结果表明,转移系数最大的是Cr,其次是Cu、Pb、Zn,最后是Ni,说明在土壤淋洗过程中Cr最先达到质量转移的平衡状态,然后是Cu、Pb、Zn,最后是Ni。     

4-甲基喹啉的微生物降解研究

从处理油制气废水的活性污泥中分离得到一株可降解喹啉的菌Q10，经鉴定为睾丸酮丛毛单胞菌(Comamonas testosteroni)。该菌还可以降解4——甲基喹啉，本文着重研究了该菌在好氧条件下对4——甲基喹啉降解特性。实验结果表明，该菌在碱性条件下比在酸性条件下更有利于4——甲基喹啉的降解；温度为30℃时降解较快；振荡速度对降解没有明显影响；在适当的细菌浓度和底物浓度水平上，4——甲基喹啉具有较高的降解效率。实验也表明，菌Q10是一株喹啉衍生物广谱降解菌，具有重要的实用价值。     

湄洲湾海域营养状态评价

根据１９９２年夏秋两季湄洲湾海域水质监测结果，应用营养质量指数法和营养指数法进行营养水平评价。评价结果表明：ＮＱＩ值在１６８～３９４范围内，平均值为２６６，Ｅ值在０２７～１６６范围内，平均值为０７１，湄洲湾海域属于中等营养水平，水质良好，但近岸局部海域已处于富营养水平。Ｎ／Ｐ比值为５７∶１，Ｎ是该海域控制因子     

Effects and mechanisms of meta-sodium silicate amendments on lead uptake and accumulation by rice

The objectives of this research were to study the effects of Na₂SiO₃ application on the uptake, translocation, and accumulation of Pb in rice and to investigate the mechanisms of Pb immobilization by Na₂SiO₃ in paddy rice soils and rice plants. Pot experiments were conducted using a Cd-Pb-Zn-polluted soil and Oryza sativa L. ssp. indica cv. Donglian 5. L₃-edge X-ray absorption spectroscopy was used to identify Pb species in soils and roots. The results showed that the application of Na₂SiO₃ increased soil pH and available soil Si but decreased DTPA-extractable Pb in the soil. High dose of Na₂SiO₃ (12.5 g/kg) reduced the Pb level in brown rice as it inhibited Pb transfer from soil to rice grains, especially Pb transfer from the root to the stem. The Pb X-ray absorption near-edge spectroscopic analysis revealed that application of high dose of Na₂SiO₃ increased Pb-ferrihydrite and PbSiO₃ precipitates in the soil and in the root while it reduced Pb-humic acids (Pb-HAs) in the soil and Pb-pectin in the root. The decrease in Pb availability in the soil can be partly attributed to increase the precipitation of PbSiO₃ and the association of Pb²⁺ with Fe oxides in the soil. The inhibition of the root-to-stem translocation of Pb was partially due to the precipitation of PbSiO₃ on the root surfaces or inside the roots.