The effect of nitrogen deficiency,methionine and inhibitors of methionine metabolism on the DMSP contents of Tetraselmis subcordiformis (Stein)

The unicellular alga Tetraselmis (Platymonas) subcordiformis (Prasinophyceae) displayed a two-phase increase in DMSP (dimethylsulfoniopropionate) contents in response to nitrogen deficiency. In the first phase, DMSP pools increased by 75% within 24 h. The second increase in DMSP was observed after 14 d and was accompanied by cyst formation. Methionine metabolism was involved in DMSP accumulation. A 2.6-fold increase of the DMSP pool could be induced by supplementing a complete ASP (artifical seawater Provasoli) medium with 100 M L-methionine. Inhibition of methionine utilization by T. subcordiformis caused by the addition of S-adenosylhomocystein, a competitive inhibitor of S-adenosylmethionine-dependent transmethylases, resulted in a 24% increase of DMSP contents after 7 h. DMSP accumulation after hyperosmotic shock was significantly delayed when methionine liberation from proteins was inhibited by a set of protease inhibitors. A model for the mechanism of DMSP accumulation is presented on the basis of these data and additional information from the literature. It is proposed that methionine availability in T. subcordiformis determines the rate of DMSP synthesis.     

基于遥感尾气监测的柴油车气态污染物排放因子计算方法研究

采用遥感尾气测试系统实测了柴油车在实际道路工况下的CO、HC和NO排放特征,修正了排放因子的计算方法,并与车载排放测试系统（PEMS）实测结果进行了验证,获得了实测车辆的CO、HC和NO排放因子.测试结果显示,在各种遥感监测的工况下柴油车尾气中均含有较高浓度的氧气,未考虑氧气影响的燃烧方程反演获得的各污染物体积浓度计算值与PEMS实测值的偏差较大,且氧气浓度越大,偏差越大.经过氧气修正的燃烧方程反演计算的尾气浓度与PEMS实测值吻合度大幅提升,适用于实际工况下遥感检测车辆尾气的反演计算.修正算法得到CO、HC和NO的排放因子离散性较小,精确度较高,可以为量化柴油车尾气排放贡献提供科学依据.     

基于稳定氢同位素的太原市大气单环芳烃来源

采集太原市城北和城南区域环境空气和5类污染源挥发性有机物样品,测定样品中典型单环芳烃稳定氢同位素（δD）组成,基于同位素质量平衡原理计算单环芳烃从源到环境空气受体的δD初始混合值,探讨单环芳烃来源.结果表明,柴油挥发源、溶剂挥发源、汽油挥发源（97^#）、汽油挥发源（95^#）、机动车尾气（97^#）、机动车尾气（95^#）和民用燃煤源中单环芳烃δD范围依次为：（-138.7‰~-115.5‰）、（-147.0‰~-121.0‰）、（-150.8‰~-117.6‰）、（-131.8‰~-113.8‰）、（-171.2‰~-120.0‰）、（-138.9‰~-102.7‰）和（-168.3‰~-142.3‰）,民用燃煤源中单环芳烃δD显著贫重氢同位素（D）组成,机动车尾气源与汽油挥发源中苯的δD相比显著贫D,可用于探索污染物转化过程;城北和城南环境空气中δD范围为（-131.7‰~-115.1‰）和（-131.9‰~-74.9‰）,δD初始混合值为-138.4‰和-173.9‰,体现了其来源差异.     

新型厌氧多级喷动床及其厌氧氨氧化脱氮性能分析

为改善厌氧反应器内的流态,加快污泥的颗粒化和形成具有生态梯度的微生物生态系统,设计并制作了新型厌氧多级喷动床,实验测试了反应器的水力喷动、气体喷涌和污泥分层分级现象。在常温下,利用新型厌氧多级喷动床接种混合污泥,经过42 d的培养,成功启动厌氧氨氧化反应器,稳定运行18 d后,NH₄+-N、NO₂--N去除率均达到90%以上。启动60 d后,反应器底部出现大量粒径2 mm左右的颗粒污泥,且污泥具有良好的稳定性和沉降性能,沉降速度达到70 m/h。结果表明:厌氧多级喷动床因其特殊的水力结构,可有效加快污泥的颗粒化。     

Development of a static test apparatus for evaluating the performance of three PM2.5 separators commonly used in China

PM_(2.5) separator directly affects the accuracy of PM_(2.5) sampling.The specification testing and evaluation for PM_(2.5) separator is particularly important,especially under China's wide variation of terrain and climate.In this study,first a static test apparatus based on polydisperse aerosol was established and calibrated to evaluate the performance of the PM_(2.5) separators.A uniform mixing chamber was developed to make particles mix completely.The aerosol concentration relative standard deviations of three test points at the same horizontal chamber position were less than 0.57%,and the particle size distribution obeyed logarithmic normal distribution with an R~2 of 0.996.The flow rate deviation between the measurement and the set point flow rate agreed to within ± 1.0% in the range of -40 to 50℃.Secondly,the separation,flow and loading characteristics of three cyclone separators(VSCC-A,SCC-A and SCC112) were evaluated using this system.The results showed that the 50% cutoff sizes(D_(50)) of the three cyclones were 2.48,2.47 and 2.44 μm when worked at the manufacturer's recommended flow rates,respectively.The geometric standard deviation(GSD) of the capture efficiency of VSCCA was 1.23,showed a slightly sharper than SCC-A(GSD = 1.27),while the SCC112 did not meet the relevant indicator(GSD = 1.2 ± 0.1) with a GSD = 1.44.The flow rate and loading test had a great effect on D_(50),while the GSD remained almost the same as before.In addition,the maintenance frequency under different air pollution conditions of the cyclones was summarized according to the loading test.     

基于FY-4A卫星数据反演气溶胶光学厚度及分析应用

风云四号A星（FY-4A）是我国新一代静止气象卫星,多通道扫描成像辐射计（AGRI）是风云四号静止气象卫星的主要载荷之一.为探究FY4A数据用于气溶胶光学厚度（AOD）反演的可行性,基于FY-4A/AGRI数据,利用暗像元算法对2019年2月23~26日及10月27~30日京津冀地区AOD进行反演研究,并与AERONET地基观测AOD数据进行了对比分析.结果表明,基于FY-4A数据及构建响应函数库,通过暗像元方法能较好的反演出京津冀地区气溶胶空间分布;AOD主要的高值区体现在京津冀中南部地区并向周边郊区逐渐降低,在AOD值较大时此特征较为明显;将反演值与同期AERONET地基观测数据对比验证,相关系数达到0.869,均方根误差为0.221,表明AOD反演值与观测值吻合较好,FY-4A卫星数据反演AOD具有一定可行性.     

中国工业各行业煤炭消费总量控制的环境效应:基于36个工业行业的实证研究

文章基于对中国36个工业行业2001-2017年煤炭消耗数据和工业污染排放数据的分析,创新性地提出了"煤炭消费减排弹性系数",用以评价各行业煤炭消费减量对减少各类工业污染的直接效果,并借助面板回归模型,分析现阶段影响中国工业煤炭消费与污染排放协调的关键因素。结果表明:在"煤炭消费减排弹性系数"的衡量和区分下,2011-2017年间中国工业各行业煤炭消费与污染排放总量控制整体成效显著,但结构上稍有不协调,煤炭消费减量对废水排放的控制效果显著优于对废气和固体废弃物;面板回归结果证实了煤炭消费减量对工业污染减排具有显著的直接作用,并且识别出工业各行业研发创新与污染治理投入是进一步协调能源消费与环境污染的重要因素,对今后中国工业各行业实现资源有效利用、与环境协调发展的目标具有重要意义。     

海水入侵指标对比分析与评价—以珠江口地下水含水层为例

合理评价海水入侵对于地下水含水层管理和居民生活健康有着重要的意义。当前海水入侵评价应用较广泛的为包含单一因子和基于统计分析的多种水化学方法。本文综合阐述了海水入侵评价中所用的水化学指标、原理与方法,包括在国内评价体系中少见的一些方法,并以珠江口地下水含水层为例,对比了各种指标的有效性,评价了各类方法的优缺点以及在实际应用中可能产生的问题。结果显示,以Cl-和TDS作为简单直接的单因子可以快速评价海水入侵,尤其对于大范围的海水入侵评价十分有效。而和Ca2+,HCO₃-,SO₄2-等变化有关的指标具有地域性,在研究区对海水入侵的指示并不是十分敏感。在复杂评价因子中,与离子交换有关SAR,BEX以及GQI_SWI与Cl-相关性较高,可以较好的指示海水入侵及水岩相互作用。经过分析,受到地下含水层和地表水道双重介质入侵的影响,研究区海水入侵范围在过去几个年代有向北推进的趋势。本研究对于高速经济发展下的沿海地下水含水层管理和评价有重要的指导意义。     

Regionalization based on spatial and seasonal variation in ground-level ozone concentrations across China

Owing to the vast territory of China and strong regional characteristic of ozone pollution,it's desirable for policy makers to have a targeted and prioritized regulation and ozone pollution control strategy in China based on scientific evidences. It's important to assess its current pollution status as well as spatial and temporal variation patterns across China.Recent advances of national monitoring networks provide an opportunity to insight the actions of ozone pollution. Here, we present rotated empirical orthogonal function(REOF)analysis that was used on studying the spatiotemporal characteristics of daily ozone concentrations. Based on results of REOF analysis in pollution seasons for 3 years' observations, twelve regions with clear patterns were identified in China. The patterns of temporal variation of ozone in each region were separated well and different from each other, reflecting local meteorological, photochemical or pollution features. A rising trend in annual averaged Eight-hour Average Ozone Concentrations(O_3-8 hr) from 2014 to 2016 was observed for all regions, except for the Tibetan Plateau. The mean values of annual and 90 percentile concentrations for all 338 cities were 82.6 ± 14.6 and 133.9 ± 25.8 μg/m~3,respectively, in 2015. The regionalization results of ozone were found to be influenced greatly by terrain features, indicating significant terrain and landform effects on ozone spatial correlations. Among 12 regions, North China Plain, Huanghuai Plain, Central Yangtze River Plain, Pearl River Delta and Sichuan Basin were realized as priority regions for mitigation strategies, due to their higher ozone concentrations and dense population.