Acid Deposition in the Tuscan Appennines During the Dry Period 1988-89

The typical parameters of acid precipitation are evaluated in the forest of Vallombrosa (Tuscan Appennines) during the dry period 1988-89. Individual rain events (dry and wet deposition) were sampled in a clearing of the forest and below the canopy of an evergreen tree as well as a deciduous broadleaf tree.

In atmospheric precipitation the pH values usually vary around 4.4, with neutralization in the hot season due to calcareous material from distant sources. Relatively large concentrations of Pb and Cd are found in rain, but only in a small amount in canopy leachate. Aluminium, manganese and iron are more significantly washed off than Pb and Cd.     

高中速过滤器的选择

介绍了高中速过滤器的应用环境、工作原理和结构组成,并从结构组成及工艺环境和实际应用性价比方面,提出实际工作时选择高中速过滤器的注意事项。     

刮油刮渣机的结构设计与应用选择

介绍了刮油刮渣机的工作原理和基本结构组成及应用结构方式,并从工艺环境及应用选择的性价比方面,提出实际工作时选择刮油刮渣机的注意事项,达到设备的最大合理化应用。     

有机污染胁迫对人工湿地中浮萍抗氧化系统的影响

湿地植物在处理高负荷有机废水时会受到不同程度的氧化胁迫。本研究基于对浮萍的有机污染胁迫模拟系统,通过对浮萍脂质过氧化和抗氧化防御系统的监测与分析,研究了浮萍对有机污染胁迫的耐受能力及胁迫去除后浮萍的恢复规律。结果表明,浮萍对有机污染胁迫具有较高的耐受性,在胁迫去除后,具有一定的恢复能力。在COD小于400mg/L时,浮萍并未受到氧化胁迫;当COD达到800 mg/L时,浮萍体内ROS含量上升,细胞膜脂过氧化加剧,但抗氧化酶活性升高,抗氧化物质含量增加,浮萍可保持生长,胁迫去除后,抗氧化防御系统可恢复到对照水平;当COD过高（≥1 000mg/L）,ROS急剧上升,抗氧化防御系统遭受破坏,造成不可逆伤害,胁迫去除后不能恢复正常生长。     

Sensitivity of Ozone Production to the Nmhc Composition, Aerosol Back-Scattering and High Chimney Emission

In this paper, three sensitivity studies are designed to analyze the effect of the NMHC (Non-Methane HydroCarbon) composition, the aerosol back-scattering and the high chimney NO_x emission to the photochemical prodution of ozone by using a one-dimensional photochemistry-diffusion model under a favourable meteorological condition. Measurements of the NMHC composition in Taipei indicated that the percentage of iso-butene, cis-2-butene, trans-2-butene and benzene in a unit volume was much higher than of those observed in other major cities. the high ratio of benzene was directly linked to its high percentage in gasoline. As to the unusually high amount of iso-butene, cis-2-butene and trans-2-butene, more researches are needed to identify their source. Concerns are raised as to how productive is NMHC composition is to the photochemical production of the surface ozone. A rough estimate shows that the total reactivity of the Taipei NMHC composition is about 1.21 × 10^-9 cm³ s^-1 which is 1.6 times that of the Los Angeles (LA) NMHC composition, while the simulated noon peak will be different by 28 ppbv, i.e. 18% more than that simulated with a LA composition.

Meanwhile, high aerosol loading is a serious problem in Taipei. the attenuation of the UV radiation by aerosols cannot be ignored. A numerical simulation shows that the noon ozone level will decrease from 178 to 141ppbv, i. e. about 21% reduction, with deterioration of the visual range from 85 to 5 km.

In the southern Taiwan, industry parks are mixed with the populated Kaohsiung city, hence the large emission of NO_x from high chimneys cannot be ignored. in this study, NO_x is assumed to be emitted in the layer between 235-460 m high with an emission rate of 0.05 or 0.145 ppbv/sec. the results show that the NO_x emitted from the elevated stack lead to a considerable reduction of surface ozone. Such conclusion is obtained due to the fact that a one-dimensional model is used in this paper. Whereas, if a three-dimensional regional model was used, then a higher productivity of ozone downstream would be simulated.     

有机物辛醇／水分配系数的计算方法：分子碎片常数法

辛醇／水分配系数是表征有机污染物环境行为的重要参数之一，本文应用于碎片常数计算了１３０余个有机化合物的辛醇／水分配系数对数值，通过计算值与实测值的比较发现，两者之间表现出相当好的一致性，其平均绝对误差为０．１３５，此外，还探讨了该方法应用于不同类型有机污染物时需要注意的问题。     

Compositional Limitations in Poly–3–Hydroxyalkanoates Produced by Pseudomonas oleovorans

It is well known that Pseudomonas oleovorans can utilize sodium octanoate for both cell growth and the synthesis of polyhydroxyalkanoates (PHAs), but it can utilize sodium butyrate only for limited cell growth and not for the polyester formation when this substrate is the sole carbon source. Therefore, these two substrates were evaluated as cofeeds for the possible incorporation of 3-hydroxybutyryl groups in the resulting PHA. When sodium butyrate and sodium octanoate were fed to P. oleovorans as cosubstrates in various proportions, the resultant cell density and polymer content were proportional to the amount of sodium octanoate in the feed. The PHA extracted from cells grown in all combinations of these cosubstrates had similar unit compositions of approximately 8 mole % 3-hydroxyhexanoate, 91 mole % 3-hydroxyoctanoate and 1 mole % 3-hydroxydecanoate. 3-Hydroxybutyrate units were not detected in any of the PHAs isolated, indicating that these units could not be incorporated in the copolymer synthesized by P. oleovorans either because the cell did not synthesize that monomer or, if it did, the PHA synthase could not copolymerize it with the longer chain monomers.     

江苏省13个城市联合观测的大气挥发性有机物污染特征及来源解析

江苏省是长江三角洲的重要组成,近年来以臭氧(O₃)和细颗粒物(PM_2.5)为特征的区域复合型污染突出。挥发性有机物(VOCs)是O₃和PM_2.5的重要前体物。2020年4月、8月和2021年1月在江苏省13个城市开展大气VOCs样品离线同步观测,在此基础上分析了江苏省大气VOCs的浓度水平、化学组成和空间分布。整体来看,全省平均VOCs体积分数为40.3×10^-9,其中烷烃(41.8%)是主要贡献者,其次为含氧有机物(16.6%)、芳香烃(12.5%)、卤代烃(12.9%)和烯烃(9.6%)。从具体城市来看,VOCs高值区主要集中在苏南及苏中地区,呈现出明显的“南高北低”的区域分布特征,排名前3的城市分别为常州(52.0×10^-9)、泰州(49.8×10^-9)和苏州(45.2×10^-9)。臭氧生成潜势(OFP)表明,芳香烃和烯烃是对江苏省O₃生成贡献最大的组分,OFP排名前3的组分均包括间/对二甲苯、甲苯和乙烯。利用正交矩阵因子(PMF)模型对江苏省VOCs进行来源解析,共解析出5个因子。工业排放是主要贡献者(40.1%),之后依次为机动车尾气(33.0%)、溶剂与涂料使用(15.9%)、油气挥发(8.4%)和天然源(2.6%)。对于省内各市而言,VOCs来源结构具有差异。常州、苏州工业排放源相对贡献最高;连云港、徐州、扬州和淮安的机动车尾气相对贡献较高;溶剂与涂料使用和油气挥发对各市VOCs贡献较低。优先控制交通相关排放和工业相关排放能够有效地控制长三角中部地区的大气O₃和PM_2.5污染问题。     

湖泊微生物与溶解有机质相互作用关系研究进展

溶解有机质(DOM)参与湖泊元素生物地球化学循环,为微生物生存代谢提供能量来源和物质基础,与微生物之间存在复杂的相互关系。文章综述了DOM表征手段,阐述了湖泊微生物与DOM相互作用关系及其代谢机制,探讨了在气候变化背景下湖泊微生物与DOM对气温升高、盐化、富营养化等关键环境因子的响应。未来需进一步开展陆源DOM输入对湖泊生态系统影响研究,探究湖泊碳库的形成过程及其机制,揭示微生物作用对湖泊碳储存的影响,深化对湖泊生态系统固碳潜力的认识。     

2009—2018年拉萨市降水化学组成特征及变化趋势

基于2009—2018年采集的拉萨市270个降水样品,分析了降水的pH、电导率、水溶性离子浓度特征及变化趋势;应用相关性分析和主成分分析等溯源方法,探讨了降水中水溶性离子的潜在来源。结果表明:拉萨市降水年均pH变化范围为7.34~7.87,平均值为7.56,呈弱碱性;电导率变化范围为1.24~5.64 mS/m,平均值为3.91 mS/m,低于北京市、西安市等大部分城市。降水中水溶性离子平均浓度大小顺序为Ca²⁺> SO₄^2-> Cl^-> K⁺> Mg²⁺> NO^-₃ > Na⁺> NH⁺₄ > F^-。近年SO₄^2-、Cl^-、NO^-₃等阴离子浓度占比迅速升高的趋势需要格外警惕。来源分析表明:阴离子的来源较为一致,主要来自汽车尾气排放;阳离子Ca²⁺和Mg²⁺主要来自地表土壤和浮尘,它们对降水pH起到了中和作用。