太湖西岸湖滨带沉积物氮磷有机质分布及评价

采集了太湖西岸湖滨带的表层沉积物,研究了沉积物中氮、磷和有机质的空间分布并进行评价.结果表明,表层沉积物氮、磷和有机质含量基本上呈由近岸向远岸递增的趋势,各点表层沉积物有机质平均含量7 124.00 mg.kg-1,介于2 261.78～11 963.10 mg.kg-1;总氮平均含量819.20 mg.kg-1,介于343.20～1 390.12 mg.kg-1;总磷平均含量379.39 mg.kg-1,介于197.46～570.85 mg.kg-1.沉积物中C/N值为9.5.沉积物中有机质及营养盐来源于湖中藻类和水生高等植物.采用有机指数和有机氮评价太湖西岸湖滨带沉积物的环境质量,有机指数平均为0.037,有机氮为0.044%,总体上属于尚清洁范畴.远岸端点位沉积物有机指数及有机氮含量均较高,存在转为有机污染的风险.     

Promote Sustainable Development for Irrigated Rice Through SSNM Technology in China

Abstract

Today, the overuse of nitrogen (N) fertilizer and high N loss result in serious nitrate pollution of water and deter the sustainable development of agriculture and social economy. A recently developed site-specific nutrient management (SSNM) can reduce fertilizer-N use while preventing the yield from falling. In this paper, we raise the question of fertilizer N application in rice production through a survey of farmers' practice of fertilizer N in 18 villages of four provinces. The average rate of N application for rice production in the 18 villages was 190 kg/ha, and 76% to 100% of the total fertilizer N which was applied within 10 days after transplanting resulted in lots of nitrate leached into water. Furthermore, we tested the effect of SSNM through farmer participatory trial. The SSNM technology maintained rice yields with significantly less fertilizer N and there was no increase in labor input, as much as 31% fertilizer N were saved with the SSNM technology. Finally, the paper points that extension and further research of the SSNM technology should be an effective method to deal with the contradiction of population, food and nitrate non-point pollution of water resource and promote the sustainability of agriculture.     

新形势下加强高校学生工作队伍建设的思考

长期以来，人们对高校学生工作队伍建设缺乏足够的重视，这是造成高校学生工作队伍不稳定，学生工作缺乏实效性的重要原因之一．本文从高校学生工作队伍的地位、作用、待遇、现状等方面进行了深入的探讨，并提出了若干行之有效的途径和措施。     

长江源区夏季径流量变化及其与高原夏季风和南亚夏季风的关系

基于长江源区直门达水文站1957～2016年夏季径流量实测资料、1957～2016年的青藏高原夏季风指数及南亚夏季风指数等资料，利用小波分析、突变检验、滑动相关系数等方法分析了长江源区夏季径流量的变化特征及与高原夏季风和南亚夏季风的关系。研究发现：近60年长江源区夏季平均流量呈增加趋势，在1957～1997年夏季平均流量整体偏少，1998～2016年流量开始增多；长江源区夏季平均流量在1995年前后发生了一次由减少趋势转为增多趋势的显著突变。长江源区夏季平均流量在年际变化上与高原夏季风和南亚夏季风存在显著的正、负相关关系，并且高原夏季风和南亚夏季风存在显著的负相关关系。高原夏季风和南亚夏季风通过大气环流变化来影响源区夏季降水，进而影响其径流。因此对高原夏季风以及南亚夏季风的研究可为预测长江源区流域内水文过程以及水资源的变化提供一定的科学参考。     

岷沱江流域水环境治理绩效综合评价方法研究

为全面研究生态文明背景下岷沱江流域水环境治理成效，该研究从水生态保护与修复、水污染治理与控制、水资源开发利用和社会经济承载4个维度构建评价指标体系，先采用灰色关联分析法和均方差决策法建立组合权重，再通过加权综合指数法和理想解模型对2011~2017年岷沱江流域10个主要地级市的水环境治理绩效进行动态评价，最后利用ArcGIS10.5软件进行评价结果的时空分异性的可视化。研究表明：在水环境综合管理下，岷沱江流域水环境治理绩效水平呈上升的趋势。空间分布上，虽岷沱江流域上、中、下游的水环境治理绩效整体水平差异性逐渐缩小，但流域中各地级市在水污染治理与水资源开发利用上存在明显的差异性，今后岷沱江流域应重点控制水污染和优化水资源配置，统筹流域可持续发展的水环境管理。     

大城市群(圈)资源环境一体化与区域可持续发展研究——以珠江三角洲城市群为例

21世纪，全球竞争的基本单位将是以中心城市为核心的城市群（圈）。基于对大城市群发展趋势及其环境问题的基本认识，文章以珠江三角洲城市群为例，分析了其发展现状及存在环境问题，阐述了珠三角城市群未来发展趋势，初步给出了城市群环境问题解决的途径，提出了珠三角城市群资源环境一体化的框架和区域可持续发展模式。     

Nutrient fluxes at the landscape level and the R* rule

Nutrient cycling in terrestrial ecosystems involves not only the vertical recycling of nutrients at specific locations in space, but also biologically driven horizontal fluxes between different areas of the landscape. This latter process can result in net accumulation of nutrients in some places and net losses in others. We examined the effects of such nutrient-concentrating fluxes on the R* rule, which predicts that the species that can survive in steady state at the lowest level of limiting resource, R*, can exclude all competing species. To study the R* rule in this context, we used a literature model of plant growth and nutrient cycling in which both nutrients and light may limit growth, with plants allocating carbon and nutrients between foliage and roots according to different strategies. We incorporated the assumption that biological processes may concentrate nutrients in some parts of the landscape. We assumed further that these processes draw nutrients from outside the zone of local recycling at a rate proportional to the local biomass density. Analysis showed that at sites where there is a sufficient biomass-dependent accumulation of nutrients, the plant species with the highest biomass production rates (roughly corresponding to the best competitors) do not reduce locally available nutrients to a minimum concentration level (that is, minimum R*), as expected from the R* rule, but instead maximize local nutrient concentration. These new results require broadening of our understanding of the relationships between nutrients and vegetation competition on the landscape level. The R* rule is replaced by a more complex criterion that varies across a landscape and reduces to the R* rule only under certain limiting conditions.     

Online investigations on ozonation products of pyrene and benz[a]anthracene particles with a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer

The reaction products of ozone with pyrene and benz[a]anthracene absorbed on azelaic acid particles under the pseudo-first-order reaction conditions have been investigated with a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS). The pyrene and benz[a]anthracene particles with the initial concentrations of ～1 mg m^?3 are respectively exposed to ～22 ppm ozone in a reaction chamber with a volume of ～180 L. The time-of-flight mass spectra of the particulate ozonides are obtained. The assignments of the mass spectra reveal that 4-carboxy-5-phenanthrene-carboxyaldehyde (71%) and hydroxypyrene (23%) are the main solid state ozonides of pyrene, while 2-(2-formyl)phenyl-3-naphthoic acid (35%), hydroxybenz[a]anthrone (30%), and benz[a]anthracene-7,12-dione (18%) are the main solid state ozonides of benz[a]anthracene. The pathways of the ozonations are proposed in the paper.     

游离态金属络合物解离稳态动力学的数学模拟

在有配位体存在的条件下，利用阳极溶出伏安法测得的水相游离金属含量通常偏高，本研制根据电化学、化学动力学和迁移动力学的基本原理，建立了描述扩散层中金属络合物解离反应和不同形态物质迁移过程中的物理模型和相应的数学模型。     

The electrochemical selective reduction of NO using CoSe2@CNTs hybrid

Converting the NO from gaseous pollutant into NH₄ ⁺ through electrocatalytical reduction using cost-effective materials holds great promise for pollutant purifying and resources recycling. In this work, we developed a highly selective and stable catalyst CoSe₂ nanoparticle hybridized with carbon nanotubes (CoSe₂@CNTs). The CoSe₂@CNTs hybrid catalysts performed an extraordinary high selectivity for NH₄ ⁺ formation in NO electroreduction with minimal N₂O production and H₂ evolution. The specific spatial structure of CoSe₂ is conductive to the predominant formation of N-H bond between the N from adsorbed NO and H and inhibition of N-N formation from adjacent adsorbed NO. It was also the first time to convert the coordinated NO into NH₄ ⁺ using non-noble metal catalysis. Moreover, the original concept of employing CoSe₂ as eletrocatalyst for NO hydrogenation presented in this work can broaden horizons and provide new dimensions in the design of new highly efficient catalysts for NH₄ ⁺ synthesis in aqueous solution.