H2O2、Na2FeO4去除土壤中总石油烃的反应动力学

利用H2O2、Na2FeO42种氧化剂对土壤中TPH进行去除实验,根据反应条件和反应速率的关系建立反应动力学模型,并对反应过程中反应速率变化、半衰期、TPH去除率等因素进行讨论和对比,寻找其反应规律.结果 表明:H2O2去除TPH过程符合一级反应动力学模型.Na2FeO4去除TPH过程符合二级反应动力学模型,H2O2浓度增大导致反应动力学常数增加,Na2FeO4浓度增大导致反应动力学常数减小.采用0.078,0.156,0.234 mol/L 3种浓度H202溶液与TPH的初始反应速率分别为0.61×10-3,1.38×10-3,2.09x 10-3 tool/(L·min),浓度为0.070,0.140,0.210 mol/L的Na2 FeO4溶液与TPH的初始反应速率分别为13.30× 10-3,20.47×10-3,12.86× 10-3 mol/(L· min).2种氧化剂与TPH的反应速率大小为:Na2 FeO4＞H2O2.H2O2、NaFeO4与TPH反应半衰期分别为40.40～66.50,4.10～7.14 min.H2O2的半衰期约为Na2FeO4的10倍.2种氧化剂对土壤中TPH去除率均可达到60％以上,但利用率较低.总结了2种氧化剂在去除TPH过程中反应速率、半衰期和去除率的特点,最终筛选并优化反应条件,为黄土高原土壤修复提供参考.     

天津市PM2.5中二次硝酸盐形成及防控

二次硝酸盐是PM_2.5中的重要二次无机离子组分,为了解PM_2.5中二次硝酸盐的形成及防控途径,基于天津市城区点位2018~2019年高时间分辨率的PM_2.5在线监测数据,对气溶胶颗粒物的离子组分、pH值、NH₃-NH₄⁺和HNO₃-NO₃^-浓度分布以及硝酸铵形成的敏感性进行了研究.结果表明,天津PM_2.5平均浓度为58μg·m^-3,PM_2.5中主要离子组分为NO₃^-、NH₄⁺、SO₄^2-、Cl^-和K⁺,在PM_2.5中的占比分别为18.4%、11.6%、10.3%、3.3%和2.6%,PM_2.5及主要组分浓度均在采暖季高、非采暖季低.气溶胶颗粒物整体呈现弱酸性,平均pH值为5.21,季节分布为春冬季节高、夏秋季节低,日变化趋势表现为早间（00：00~08：00）低,其他时间略高.NH₃和HNO₃的平均浓度水平分别为16.7μg·m^-3和1.2μg·m^-3,NH₃浓度在每年的4~9月相对较高,10月~次年2月浓度相对较低;HNO₃浓度水平月际变化不明显.除夏季外,其他季节NH₃浓度均为早晚较高,其他时段较低;HNO₃浓度整体呈现白天相对略高,晚上相对略低的特点.不同pH值下NH₃与NH₄⁺、HNO₃与NO₃^-的浓度分布呈现明显的非线性关系,早晚NH₄⁺与NO₃^-的浓度均较高,pH值与NH₃和NH₄⁺以及HNO₃与NO₃^-的浓度分布均为非线性.敏感性图表明,2018~2019年天津市硝酸铵的形成主要处于HNO₃敏感区域,部分处于NH₃&HNO₃敏感区域.从季节分布上看,春季、秋季和冬季硝酸铵的形成主要处于HNO₃敏感区域,夏季硝酸铵的形成主要处于HNO₃和NH₃&HNO₃敏感区域.为有效减少天津市PM_2.5中二次硝酸盐的形成,春季、秋季和冬季主要开展HNO₃前体物（NO_x）的控制,夏季主要开展HNO₃前体物（NO_x）和NH₃的协同控制.     

以福州为示范的城市空气质量实时精细化模拟与预报

本研究在已有空气质量站点的基础上,采用多功能、高效、小巧的传感设备进行监测加密,利用大数据的分析机理与空气质量模型的城市计算技术,以海峡西岸城市群中的福州市为示范,建设城市空气质量实时精细化模拟与预报系统。实时分析城市细粒度(1km×1km)的空气质量,有效提高了城市不同地理位置污染物浓度差异性的分辨率,同时对城市空气污染的发展趋势提出预测,为精细化分析污染成因提供基础数据,从而为环境管理提供决策辅助支持、市民出行提供帮助与指导。     

苦草（Vallisneria natans）根系对沉积物中各形态磷的影响

采用磷分级提取的方法研究苦草(Vallisneria natans)生长过程中根系分布与沉积物不同形态磷和总磷的变化过程.在实验开始后20、50、80 d,分别测定苦草根系在沉积物的分布及沉积物中各形态磷的垂直变化.结果表明,苦草根系在实验装置中垂直分布在0~14 cm区域内.平均每株苦草根系根数为58条,平均根长为5.86 cm.苦草根系生物量在沉积物深度0~3、4~6、7~10、11~14 cm分配的质量分数分别为45.99%、32.75%、16.03%、5.23%.沉积物中总磷(TP),NaOH提取磷(NaOH-P)和有机磷(OP)含量在苦草根系分布集中区域内显著降低(P<0.05).HCl提取磷(HCl-P)和无机磷(IP)的含量无显著差异(P>0.05).     

一种能同时固定CO2和N2的微生物——兼性固CO2、N2菌的分离鉴定及其验证实验

"温室效应"日趋严重,生物固碳特别是微生物固碳将发挥独特的作用.固定N2的微生物固氮菌和固定CO2的微生物固碳菌早已被研究和发现,但能同时固定大气中的CO2、N2并以CO2、N2分别为碳、氮源的微生物至今未见报道,本研究称之为兼性固CO2、N2菌.研究通过固碳菌、固氮菌培养基的优化组合出无碳、氮培养基(分别以空中的CO2、N2为碳源和氮源);通过无氮碳源的兼性固碳氮菌培养基进行分离,筛选分离到一株分别以CO2和N2为碳源和氮源.通过对该菌株的生长特性和固碳酶活性及固氮酶活性进行测定;利用PCR和琼脂糖凝胶电泳技术检测到该菌含有固碳酶RubisCO中cbbL基因及固氮酶nifH基因片段的特异性条带;对该菌进行对照验证实验证明该菌能同时固定空气中的CO2和N2并分别以CO2和N2为碳源和氮源;最后对其形态观察和16SrRNA全序列分析证明该菌株HSJ隶属于链霉菌.     

北京温榆河流域微生物污染调查研究

随着工业化和城市化进程的加快,我国河流普遍受到了不同程度的水质污染,而微生物指标对于水质评价具有重要作用.本研究选取细菌总数、总大肠菌群、粪大肠菌群以及SC噬菌体、F噬菌体作为指示微生物对北京市温榆河开展了历时一年多的调查研究,结果表明,除了有机污染和富营养化问题外,温榆河流域的微生物污染非常突出.温榆河上游已经受到了一定程度的微生物污染,微生物浓度(以粪大肠菌群为例)波动较大(5.01×10²~5.37×10⁶个·L^-1);下游受清河、坝河等排水河道的影响,微生物污染普遍严重(均值达6.3×10⁶个·L^-1以上),与地表水Ⅴ类水质标准(GB 3838—2002)相比FC浓度平均超出两个数量级.统计分析显示,温榆河微生物污染受季节的影响并不显著(p>0.05),表明人为因素很可能是其主要影响因素.温榆河处于微生物高污染水平,可能威胁地下水水质和农作物质量安全,应从源头加强微生物风险控制.     

滇池流域水污染防治规划与富营养化控制战略研究

根据滇池水污染防治的决策需求,在系统分析滇池水环境演变趋势和评估演变诱因的基础上,以流域水环境承载力方案及容量总量控制方案为基础,提出了滇池流域水污染防治中长期规划研究的方法体系,包括:问题驱动、调查诊断、规划基础、规划方案、评估调控、规划战略;提出了源头控制、工程控制和末端控制相结合的污染减排对策;通过构建3个尺度、8个分区及4个规划重点的流域污染减排集成体系及情景方案,来实现在2个规划期、3类水质目标、4种社会经济发展情景下的规划目标.在此基础上,提出了滇池富营养化控制的战略思路.     

Contents and sources of polycyclic aromatic hydrocarbons and organochlorine pesticides in vegetable soils of Guangzhou, China

We investigated contents, distribution and possible sources of PAHs and organochlorine pesticides (Ops) in 43 surface and subsurface soils around the urban Guangzhou where variable kinds of vegetables are grown. The results indicate that the contents of PAHs (16 US EPA priority PAHs) range from 42 to 3077 microg/kg and the pollution extent is classified as a moderate level in comparison with other investigations and soil quality standards. The ratios of methylphenanthrenes to phenanthrene(MP/P), anthracene to anthracene plus phenanthrene (An/178), benz[a]anthracene to benz[a]anthracene plus chrysene (BaA/228), indeno[1,2,3-cd]pyrene to indeno[1,2,3-cd]pyrene plus benzo[ghi]perylene (In/In+BP) suggest that the sources of PAHs in the soil samples are mixed with a dominant contribution from petroleum and combustion of fossil fuel. The correlation analysis shows that the PAHs contents are significantly related to total organic carbon contents (TOC) (R2=0.75) and black carbon contents (BC) (R2=0.62) in the soil samples. Dichlorodiphenyltrichloroethane and metabolites (DDTs) and hexachlorocyclohexanes and metabolites (HCHs) account largely for the contaminants of OPs. The concentrations of DDTs range from 3.58 to 831 microg/kg and the ratios for DDT/(DDD+DDE) are higher than 2 in some soil samples, suggesting that DDT contamination still exists and may be caused by its persistence in soils and/or impurity in the pesticide dicofol. The concentrations of HCHs are 0.19-42.3 microg/kg.     

Mutual effects of cadmium and phosphate on their adsorption and desorption by goethite

Adsorption of cadmium (Cd) and phosphate by oxides or soils has been extensively studied, but the adsorption/desorption kinetics and mutual effects of these two species in co-existing systems has received little attention. In this study, a batch equilibration method was used to investigate the effect of phosphate and its application time on Cd adsorption and desorption on goethite. The influence of Cd and its application time on phosphate sorption and desorption kinetics was also determined. For Cd adsorption, phosphate was introduced into the system by two sequences: pre-treating goethite at 40 (degrees)C for 1 week, and applying with Cd simultaneously. Similarly, for phosphate sorption, Cd was applied by pre-treating goethite at 40 (degrees)C for 1 week or simultaneous addition with phosphate. Results demonstrated that phosphate added to goethite enhanced Cd adsorption, and facilitated Cd release as compared to untreated goethite. Cadmium had slightly higher adsorption, but a significantly faster desorption rate from the goethite simultaneously treated with phosphate and Cd, as compared to phosphate-pretreated goethite. Cadmium and its application time had little impact on phosphate sorption by goethite. However, phosphate desorption kinetics was affected by Cd application time. When the sorption time was short (15 min), phosphate desorption was faster from the goethite that was simultaneously treated with phosphate and Cd, as compared to Cd pretreated or untreated goethite. In contrast, a longer sorption time (4 weeks) resulted in a higher desorption rate of phosphate from Cd pretreated goethite than simultaneously phosphate-Cd treated goethite. This study provided useful information on adsorption/desorption kinetics in complicated Cd-phosphate-goethite systems.     

矿业城市生态风险评价研究进展

矿业城市作为我国资源供应的重点区域,对国民经济发展起着举足轻重的作用.通过文献综述的方法,在明确矿业城市生态风险评价工作意义的基础上,归纳总结了矿业城市生态风险评价的研究进展.从矿业城市生态风险评价研究主题、研究内容、评价理论框架和具体研究方法展开评述,分析了矿业城市生态风险热点关键词时区演化趋势、矿业城市生态风险基本...