缙云山土地利用方式对土壤轻组及颗粒态有机碳氮的影响

选取缙云山阳坡同一海拔处亚热带常绿阔叶林(以下简称林地)、果园、坡耕地和撂荒地这4种不同土地利用类型,在0~60 cm深度内每隔10 cm采集一个土样,测定土壤轻组有机碳氮(LFOC、LFON)和颗粒态有机碳氮(POC、PON)含量,并计算其分配比例和碳氮比.结果表明,在0~60 cm土壤深度范围内,林地转变为坡耕地后,LFOC及LFON含量分别降低了71.42%和38.46%(P0.05),转变为果园后变化不明显,坡耕地撂荒后其含量分别升高了3.77倍和1.38倍(P0.05);林地转变为坡耕地或果园后,POC及PON含量均无明显变化,而坡耕地撂荒后其含量分别增加了4.12和1.25倍(P0.05).林地转变为坡耕地后土壤LFOC及LFON分配比例显著降低,转变为果园后则明显升高,而POC及PON分配比例变化均不明显;坡耕地撂荒后,LFOC、LFON、POC、PON分配比例均显著增加.土壤SOC/TN为撂荒地(12.93)林地(8.53)果园(7.52)坡耕地(4.40),LFOC/LFON为撂荒地(16.32)林地(14.29)果园(11.32)坡耕地(7.60),POC/PON为撂荒地(23.41)坡耕地(13.85)林地(10.30)果园(9.64).以上研究结果表明林地开垦为果园或坡耕地后容易导致土壤轻组有机碳氮的损失,而坡耕地撂荒则有利于土壤活性有机碳氮的积累;林地转变为坡耕地减弱了土壤有机碳氮的活性,而林地转变为果园以及坡耕地撂荒均使土壤有机碳氮活性增强;林地转变为坡耕地和果园加剧了土壤有机质的矿化,相对而言,坡耕地撂荒后有利于土壤有机质的固定.     

DOM对被动采样技术的影响与应用

主要研究了不同浓度的天然溶解性有机物(DOM)对单片膜被动采样技术的影响.结果表明,DOM的存在会影响膜吸附有机污染物的能力:当lg KOW为3~5时,DOM对膜吸附有机物的影响较小;当lg KOW5.5时,DOM会显著增强膜的吸附能力.同时,通过低密度聚乙烯膜(LDPE)被动采样技术对太子河流域3个表层沉积物的孔隙水进行多环芳烃类(PAHs)和邻苯二甲酸酯类(PAEs)监测.结果表明,所选取的几种目标污染物在各监测点均有不同程度的检出.最后,利用商值法对太子河流域的PAHs和PAEs进行生态风险评价.结果表明,荧蒽超过水生生态基准值,其生态风险较大.     

西大海湖沉积物营养盐垂直分布特征变化分析

通过对西大海湖心柱状沉积岩芯有机质(OM)、总氮(TN)、总磷(TP)、磷形态和粒度指标的测试和分析,探讨其垂向分布特征及影响因素.结果表明,营养盐中OM、TN和TP的含量分别为0.633%~2.756%、0.150%~0.429%和648.00~1 480.67 mg·kg-1.Ca-P是TP的主要部分,占TP含量66.04%.1843~1970年间,Ca-P、IP、OM含量变化较小,Fe/Al-P、OP、TP、TN含量波动较大;1970~1996年间,Ca-P、IP、TP含量变化均呈减小趋势,Fe/Al-P、OP、OM含量不同程度上先减少后增加,TN波动较大;1996~2009年营养元素含量相对波动较大,Fe/Al-P、OP和OM的平均含量是3个阶段中最高的.西大海湖沉积岩芯营养元素污染来源以工业废水、生活污水和化肥农药的流失为主.沉积物中C/N比值显示有机质主要来源于水生生物.沉积物粒度组成以黏土和细粉砂为主.相关性研究表明,Ca-P、IP与TP均呈显著的正相关关系,表明Ca-P对IP、TP的增长贡献大.     

大气颗粒物及降尘中重金属的分布特征与人体健康风险评价

为了解PM_(2.5)、PM_(10)和降尘中Cu、Mn、Pb、Ti、V、Cd、Cr、Co、Mo、Ni等10种重金属元素的分布特征及人体健康风险,利用大流量颗粒物采样器采集了北京城区某地四季大气中PM_(2.5)、PM_(10)及降尘样品,用ICP-MS测定了上述10种金属元素的质量浓度.结果表明,PM_(2.5)和PM_(10)的年均质量浓度分别为153.40μg·m~(-3)和232.93μg·m~(-3),超出GB 3095-2012中二类环境功能区标准限值的5倍和3倍;PM_(2.5)/PM_(10)的均值为0.74,表明大气颗粒物中以粒径小于2.5μm的颗粒为主;后向轨迹分析结果表明外源颗粒物的来向随季节变化而改变,冬、春、夏、秋季主要来向为西北、北-东北、东南、东南-西北.PM_(2.5)和PM_(10)中10种元素的年均质量浓度从高到低依次为TiMnPbCuCrNiVCdMoCo,其中Ti、Mn、Pb、Cu和Cr这5种元素占10种目标元素总质量浓度的91.93%和92.49%.除PM_(10)中Cd年均质量浓度(6.53 ng·m~(-3))高于GB 3095-2012限定值(5.00 ng·m~(-3))外,其他元素的质量浓度均不超标.降尘中各元素的含量由高到低依次为TiMnPbCuNiCrVCoMoCd,Ti(2561.48μg·g~(-1))占所有元素的质量分数为72.57%,地累积指数(Igeo)结果表明,Cd(4.03)属重度污染,Pb(2.49)介于中度污染和重度污染之间,Cu(1.33)属中度污染,Ni(0.43)属轻微污染.重金属的致癌健康风险(10-4)和非致癌健康风险(1),均处于较低水平,短期内不会对人体健康造成威胁,但不能忽视长期处于此环境所带来的健康危害.     

传统北京烤鸭烤制过程中大气污染物的排放特征

烤鸭是具有北京特色的传统美食之一,制作过程采用果木炭火烤制方式,与其它食物烹饪过程存在明显的差异,国内还未对这类餐饮源的排放特征进行过系统研究,为掌握这类餐饮源排放特征,从而为污染控制提供技术依据,选取北京市具有代表性的烤鸭店,研究了其烤鸭烤制过程中大气污染物的排放特征.结果表明,传统烤鸭烤制过程中排放的油烟、颗粒物、挥发性有机物(VOCs)和醛酮类化合物的基准排放浓度分别为(0.74±0.45)、(15.32±7.93)、(7.60±3.41)和(1.22±0.59)mg·m~(-3);颗粒物排放浓度要远高于油烟排放浓度,VOCs组分构成相对复杂,既包括烷烃、烯烃、芳香烃等VOCs也包括醛酮类、醇类、酯类等含氧VOCs和卤代烃,其中3-甲基呋喃、乙醇和乙酸甲酯的浓度最高;醛酮类化合物的主要组分有乙醛、甲醛和丙烯醛等,其中C1~C3物质占72.27%.     

Quantum chemical investigation on photodegradation mechanisms of sulfamethoxypyridazine with dissolved inorganic matter and hydroxyl radical

Sulfamethoxypyridazine(SMP) is one of the commonly used sulfonamide antibiotics(SAs).SAs are mainly studied to undergo triplet-sensitized photodegradation in water under natural sunlight with other coexisting aquatic environmental organic pollutants.In this work,SMP was selected as a representative of SAs.We studied the mechanisms of triplet-sensitized photodegradation of SMP and the influence of selected dissolved inorganic matter,i.e.,anions(Br~-,Cl~-,and NO~-_3) and cations ions(Ca~(2+),Mg~(2+),and Zn~(2+)) on SMP photodegradation mechanism by quantum chemical methods.In addition,the degradation mechanisms of SMP by hydroxyl radical(OH·) were also investigated.The creation of SO_2 extrusion product was accessed with two different energy pathways(pathway-1 and pathway-2) by following two steps(step-I and step-II) in the tripletsensitized photodegradation of SMP.Due to low activation energy,the pathway-1 was considered as the main pathway to obtain SO_2 extrusion product.Step-II of pathway-1 was measured to be the rate-limiting step(RLS) of SMP photodegradation mechanism and the effect of the selected anions and cations was estimated for this step.All selected anions and cations promoted photodegradation of SMP by dropping the activation energy of pathway-1.The estimated low activation energies of different degradation pathways of SMP with OH·radical indicate that OH·radical is a very powerful oxidizing agent for SMP degradation via attack through benzene derivative and pyridazine derivative ring.     

Simulated reaction of formaldehyde and ambient atmospheric particulate matter using a chamber

The reaction of HCHO with Beijing winter's real ambient particulate matter(PM) inside a 3.3 m~3 Teflon Chamber was conducted in this study. NO_2, O_3 and H_2O gases were removed from the ambient aerosol before entering into the chamber. The decays of HCHO were monitored(acetylacetone spectrophotometry method) during the reactions at different PM number concentrations(N_a) and relative humidities(RHs), and the formed particulate formate was detected by IC and XPS techniques. The results showed that when RH was10%–15%, the decay rate of HCHO in the chamber was higher with the existence of PM from relatively clean days(with number concentration(N_a) 200,000 particle/L, 0.35–22.5 μm)compared to dirty days(N_a 200,000 particle/L, 0.35–22.5 μm). When RH increased to 30%–45%, PM can hardly have significant influences on the decay of HCHO. The formations of formate on the reacted PM were consistent with the HCHO decay rates at different ambient PM N_aand RH conditions. This is a first study related to the "real" ambient PM reacted with HCHO and suggested that in the clean and low RH days, PM could be an effective medium for the conversion of HCHO to formate.     

覆盖金属氧化物对湖泊沉积物溶解性有机质特征的影响

为揭示不同金属氧化物对湖泊沉积物DOM（溶解性有机质）影响机制,通过室内模拟试验,在沉积物表层分别覆盖Fe、Al、Mn氧化物及湖沙后培养1 a,并利用三维荧光和紫外光谱方法进行表征.结果表明:① 覆盖Al、Fe、Mn氧化物和湖沙主要降低了0~3 cm沉积物的w（DOC）,降幅分别为8.61%、6.27%、22.38%和0.44%. ② 沉积物中DOM的类络氨酸峰（peak B₁）和类色氨酸峰（peak T₂）均产生较大变化.其中三种氧化物均显著降低了上层沉积物中DOM的peak T₂,使底层DOM的peakT₂显著增加. Mn氧化物使DOM的peak B₁降低,Fe和Al氧化物使DOM的peak B₁增加,湖沙则使两类峰均降低. ③ 覆盖金属氧化物改变了沉积物DOM结构特征,其中覆盖Fe氧化物增强了其芳香性,而覆盖Mn氧化物和Al氧化却降低其芳香性,但三者均使DOM腐质化程度及官能团数量增加,并使FI（Fluorescence Index,荧光指数）增大,表明DOM向生物源转化.研究显示,沉积物表层覆盖金属氧化物影响了沉积物中DOM迁移和转化,并促进了其降解,导致其分子量和腐殖化程度增加.      

Effects of Cu2+ and humic acids on degradation and fate of TBBPA in pure culture of Pseudomonas sp. strain CDT

Soil contamination with tetrabromobisphenol A(TBBPA) has caused great concerns;however, the presence of heavy metals and soil organic matter on the biodegradation of TBBPA is still unclear. We isolated Pseudomonas sp. strain CDT, a TBBPA-degrading bacterium, from activated sludge and incubated it with ~(14)C-labeled TBBPA for 87 days in the absence and presence of Cu~(2+)and humic acids(HA). TBBPA was degraded to organic-solvent extractable(59.4% ± 2.2%) and non-extractable(25.1% ± 1.3%) metabolites,mineralized to CO_2(4.8% ± 0.8%), and assimilated into cells(10.6% ± 0.9%) at the end of incubation. When Cu~(2+)was present, the transformation of extractable metabolites into non-extractable metabolites and mineralization were inhibited, possibly due to the toxicity of Cu~(2+)to cells. HA significantly inhibited both dissipation and mineralization of TBBPA and altered the fate of TBBPA in the culture by formation of HA-bound residues that amounted to 22.1% ± 3.7% of the transformed TBBPA. The inhibition from HA was attributed to adsorption of TBBPA and formation of bound residues with HA via reaction of reactive metabolites with HA molecules, which decreased bioavailability of TBBPA and metabolites in the culture. When Cu~(2+)and HA were both present, Cu~(2+)significantly promoted the HA inhibition on TBBPA dissipation but not on metabolite degradation. The results provide insights into individual and interactive effects of Cu~(2+)and soil organic matter on the biotransformation of TBBPA and indicate that soil organic matter plays an essential role in determining the fate of organic pollutants in soil and mitigating heavy metal toxicity.     

滴定分析法在土壤胡敏酸研究中的应用

胡敏酸是土壤有机质的重要组成部分,是研究土壤有机质物理化学性质的重要环节之一。本文综述了国内外在土壤胡敏酸研究中所采用的各种分析方法,详细论述了滴定分析方法在土壤胡敏酸官能团测定、土壤胡敏酸带电性质测定以及胡敏酸与金属相互作用研究中的应用,并使用滴定分析法测定了贵州喀斯特地区石灰土胡敏酸中酸性官能团及其与Ca2+形成络合物的稳定系数。通过总结对比滴定分析法在研究胡敏酸方面的应用,本文认为现代滴定分析法在表征土壤胡敏酸物化特性和研究土壤胡敏酸演化规律等方面具有广泛应用前景。