公路两侧土壤中铅和镉污染以及存在形态分布的分析

测定了土壤中铅、镉总量,并采用五级连续浸提法和石墨炉原子吸收分光光度法对北京市3条典型公路两侧的土壤样品中铅和镉的存在形态分布进行了测定.结果表明,所选3条公路出京方向右侧的土壤铅和镉污染严重,其铅、镉总量分别是北京地区土壤铅和镉含量背景值的1.62～6.69、5.97～18.74倍.土壤中铅主要以铁锰氧化物结合态、碳酸盐结合态、有机结合态和残渣态等形式存在,镉主要以铁锰氧化物结合态和残渣态形式存在,而活性强的离子交换态浓度均较低.不容忽视的是,铅和镉的碳酸盐结合态在碱性条件下稳定,但是具有遇酸释放的隐患.     

湘江株洲段丰水期镉污染负荷总量测算及分配

以2010年8月湘江干流株洲段代表性断面水质与底泥监测资料以及其他资料为基础,采用WASP7模型模拟该江段丰水期镉浓度,并进行镉污染负荷测算与分配。研究结果表明,WASP7模型较好地重现了镉浓度的变化规律,8月份该河段上游镉入流量2 446.33 kg,下游出流量3 076.44 kg,区间增量630.12 kg,其中点源负荷量241.67 kg,占38.4%,面源负荷量304.49 kg,占48.3%,内源负荷量为83.96 kg,占13.3%。     

pH值对霞湾港沉积物重金属Zn、Cu释放的影响

以霞湾港(铜霞路段)的底泥沉积物为研究对象,采用重金属连续浸提法对重金属Zn、Cu在沉积物中的5种形态进行浸提,分析了其分布特征和在不同pH值与时间的条件下重金属的释放规律。研究结果表明,重金属Zn主要以铁锰氧化物结合态和碳酸盐结合态的形态存在,Cu主要以有机结合态和残渣态的形态存在,可交换离子态的重金属含量都很低。重金属Zn、Cu从沉积物中的释放,主要是在酸性条件下发生,在酸性区内释放量随pH的升高而迅速降低。释放能力和释放速率均为ZnCu,它们释放的过程基本相似,释放速率都比较小,向环境中的释放是个长期过程。     

不同镉污染农田土壤上秸秆和炭化秸秆分解动态及其对土壤镉的吸附特征

通过温室土壤培养实验，研究不同镉污染农田土壤上不同的作物秸秆和炭化作物秸秆还田后的分解动态和还田秸秆材料对污染土壤中镉的吸附特征，探讨秸秆和炭化秸秆还田做为重金属镉污染农田土壤修复剂的可行性。实验结果表明，还田的油菜秸秆和玉米秸秆在2种镉污染水稻土壤上6个月分解了43％-65％，秸秆炭化后还田则很稳定，2种镉污染土壤上还田6个月时累计分解量小于5％。2种镉污染土壤上还田的秸秆和炭化秸秆随还田时间延长镉含量逐渐增加。模拟镉污染土壤上，相同时期油菜秸秆中镉含量显著高于玉米秸秆，油菜秸秆炭中镉含量显著高于玉米秸秆炭。在镉污染土壤上，还田的玉米秸秆、油菜秸秆、玉米秸秆炭和油菜秸秆炭对土壤镉的净吸附量相近，均小于1．1μg／g。在模拟镉污染土壤上还田的油菜秸秆和油莱秸秆炭对土壤镉净吸附量最高分别达到2．74μg／g和7．03μg／g，分别是玉米秸秆和玉米秸秆炭的2倍，且显著高于其在镉污染土壤上的净吸附量，具有高的吸附能力。     

几种典型土壤对电动修复镉污染效果的影响

选择5种典型土壤进行了镉污染的电动修复研究。结果表明,经12 d电动修复后,黑土、潮土、红壤、水稻土和黄棕壤中镉的去除率依次为16.7%、21.0%、47.1%、10.7%和12.6%。红壤靠阳极附近Cd含量由初期435 mg·kg-1降至32.4 mg·kg-1,迁移率高达92.5%。黑土、红壤和潮土都维持了较高的电流强度和电渗流量,但由于红壤对碱的缓冲能力较强,修复效果最好。水稻土中电渗流量高,但由于电流低,镉的去除率不高,说明电动修复中电迁移作用强于电渗析。修复后,土壤中可交换态镉、碳酸盐结合态镉、铁锰氧化物结合态镉总量减少,残渣态镉总量增加,有机结合态在阳极附近总量减少、阴极附近总量增加。上述结论揭示了电动修复的土壤镉污染的主要机制,通过镉的运动轨迹和形态分布,可预测不同土壤的电动修复效果,同时能改变不同土壤的电动修复策略,为场地修复提供参考。     

微生物沥浸法去除底泥中的重金属

以硫酸亚铁盐为底物,培养以氧化亚铁硫杆菌为主要菌种的土著沥滤微生物,采用批式方法对湘江长沙段底泥进行微生物沥浸实验。实验结果表明,底物投加量与底泥固体浓度比(Sd/Sc)为1.5时已能满足底泥的微生物沥浸要求,进一步研究发现底泥固体浓度为13%、底物投加量为19.5 g/L、沥浸时间为6 d时,底泥中超标重金属Cd、Zn和Cu的去除率可分别达到83.1%、75.3%和61.2%;沥浸后底泥中大部分重金属以残渣态存在,且含量低于农用污泥中污染物控制标准,其中硫化物有机结合态Cu浸出较Zn、Cd需更低的pH,且Cu以间接机理浸出为主;以Fe2+为底物的沥浸体系中,黄铁矾的重吸附或共沉淀是沥浸实验后期重金属浸出率下降的原因之一。     

湘江株洲段镉污染动态模拟与情景分析

本研究利用美国环境保护局(USEPA)推荐的WASP水质分析模拟软件,对湘江株洲段2009年的镉浓度进行动态模拟,并进行总量控制的情景分析。对水文条件变化和源强变化2种情景下的河道镉浓度进行了预测。结果表明,WASP模型能较好重现镉浓度的时间变化规律。情景分析表明,水文条件和源强条件对镉浓度的影响在霞湾和马家河断面较为明显,且在枯水月份表现得更为明显。     

超声波辅助萃取测定土壤中有机物结合态和硫化物结合态镉的研究

正采用Tessier萃取法分析土壤中镉的形态时,为了减少操作时间,采用超声波加热法测定土壤中有机物结合态镉和硫化物结合态镉。考察了超声时间、萃取温度、超声频率、超声功率对提取效果的影响。结果表明,超声频率为68.5kHz、振荡时间为25min、萃取温度为85℃、超声功率为242W时,提取效果最好,提取时间由原来的4h缩短至25min。采用3种镉污染程度的土壤进行方法验证,发现改进的Tessier法和原来的Tessier法的检测结果基本一致,改进的Tessier法可用于土壤中有机物结合态镉和硫化物结合态镉的测定分析。     

硫化锰纳米颗粒高效去除重金属镉

中国镉污染问题日益严峻,开发高效的镉吸附剂,是解决环境镉污染问题的重要技术手段。采用共沉淀方法合成了硫化锰纳米颗粒,研究了其对重金属镉的吸附行为,并采用X射线衍射(XRD)、扫描电镜(SEM)、高分辨透射电镜(HR-TEM)、比表面积(BET)等技术手段探究了硫化锰纳米颗粒的形貌、化学组分以及镉的去除机制。结果表明,MnS纳米颗粒呈球状,平均粒径100 nm,比表面积30.56 m~2·g~(-1)。MnS纳米颗粒对Cd~(2+)的吸附动力学数据较好地符合伪二级动力学模型;吸附等温线数据较好地符合Langmuir模型,说明MnS对Cd2+的吸附是以化学吸附为主的单分子层吸附。使用Langmuir拟合的MnS饱和最大镉吸附量为349.6 mg·g~(-1),在众多镉吸附材料中处于前列。对于模拟工厂重金属废水的处理,MnS纳米颗粒可以在5 h内使镉的浓度由60 mg·L~(-1)降至国家规定排放线以下(0.1 mg·L~(-1)),且吸附过程中水体pH稳定,对水体干扰小。在多种重金属离子共存的情况下,仍可以达到接近100%的Cd~(2+)去除率。硫化锰相对稳定,在空气中放置30 d仍有80%的镉去除率。较高的离子交换量形成CdS沉淀是MnS高效去除镉的主要原因。     

Regional distribution of cadmium minerals and risk assessment for potential cadmium pollution of soil in China

系统地分析和评价了中国镉矿的区域分布及长期采选冶活动所带来的土壤镉污染风险.研究结果表明,截至2005年底,中国累计探明镉资源储量约为719.47kt,保有镉资源储量约为587.37 kt,且多与铅矿、锌矿等以共、伴生形式存在.中国镉矿主要分布在中部、西南部及华东地区,这些地区的镉资源探明储量占中国累计探明总储量的88.0％,保有储量占中国总保有储量的87.1％.据统计,中国镉采出量约为136.10 kt,主要集中在西南地区,其镉采出量占中国总采出量的59.4％.镉污染事件主要发生在镉矿相对丰富及采选冶活动较密集的云南、广东、湖南、贵州等地区,大部分矿冶区及周边土壤呈现重度镉污染,农作物中含镉量超出《食品中污染物限量》(GB2762-2005)中限值.     

Optimization of Height of Release of Air Pollutants

A number of key projects in the Environmental Protection Agency (EPA) particulate R&;D program having applicability to industry are presented. For electrostatic precipitators (ESP) there is presented the result of work on large diameter discharge electrodes which provide a decrease in penetration of up to a factor of 4 when compared to conventional small diameter electrodes. Also discussed is the multistage ESP which provides a collection efficiency that would require a collecting plate area 4 or 5 times larger with conventional ESP technology. The E-SOX technology makes use of the multistage concept to free up space in the ESP for SO₂ removals of up to 90%. Electrostatically augmented fabric filtration provides a reduction in pressure drop of about 5 0% as compared to conventional fabric filtration. Wind tunnel modeling of windbreaks for material storage piles indicates a potential for providing engineering design data that would allow significant emission reduction caused by wind erosion     

Investigation of the characteristics of the reflectivity of clouds

This paper investigates some of the reflectivity characteristics that clouds (when modelled as solid bodies) must exhibit to be compatible with observations that the reflecting surface of a cloud (i) appears almost equally bright across its face, (ii) is brightest when the cloud is opposite to the Sun but decreases in brightness as the cloud moves to other positions and (iii) increases in brightness with increasing optical thickness of the cloud in the observer's line of sight. These observations, respectively, are shown to imply that the peak value of the bidirectional total reflectivity from a cloud surface (i) increases in inverse proportion to the cosine of the angle between the Sun and the normal to the cloud surface, as the incident angle increases, (ii) appears to be directed back in the direction of the incident radiation, and (iii) increases as optical thickness of the cloud in the observer's line of sight increases. The results could have application in many fields (e.g. modelling diffuse radiance distributions for cloudy skies).     

次氯酸钠发生器的研制

介绍了电解法生产次氯酸钠的原理 ,并在原有生产工艺的基础上进行了重新设计和对设备的重新选择、改造 ,得出了各个工艺参数的最佳值 ,生产出高品质的次氯酸钠     

Comparison of methods for evaluation of activity of photocatalytic films

Objective

This work aims to investigate the correlation between the photocatalytic activity determined by methylene blue bleaching (DIN 52980), stearic acid degradation, and degradation of acetone in gas phase.

Method

The photocatalytic TiO₂ coatings included in this investigation ranged from thin commercially available coatings (Activ^TM and BioClean^TM) and ready to use suspensions (Nano-X PK1245) to lab-produced PVD and sol?Cgel coatings. XRD analysis of the photocatalytic coatings showed that all the coatings consisted of nanocrystalline anatase, although the thickness and porosity varied considerably.

Results

The study showed that the reproducibility of the activity measurements was good. However, more importantly, the investigation showed that there is a good correlation between the activities determined by the different methods even though the characteristics of the photocatalytic coatings and the organic probe molecules varied considerably.

Conclusion

The overall findings of this work suggest that there is a good correlation between the investigated methods. These results are promising for the future work concerning standardization of methods for determination of the activity of photocatalytic films.     

Impact of overexploitation of shellfish: northeastern coast of India

India has a very extensive coastline of about 7515 km, rich in diverse living resources. These resources continue to deteriorate with rampant harvesting or are altered for other uses such as aquaculture and fisheries. The present paper deals with degrading coastal habitats in northeastern India, and projects the intensity of the stress arising from the collection of tiger prawn seeds (Penaeus monodon) for aquacultural farms and molluskan shells for poultry feed and edible lime. Indiscriminate exploitation of these resources leads to a heavy reduction of the species concerned and other associated marine communities. The magnitude of such destruction has been quantified. The impacts of biodiversity loss and their after-effects on the ecobalance of this coastal system have become a matter of great concern to ecologists to maintain security and sustainability. The authors propose a public awareness program on themes relating to the importance of biodiversity for human livelihoods.     

实验室质量管理体系内部审核的策划

在实施ISO／IEC 17025：1999标准《检测和校准实验室能力的通用要求》过程中，通过实验室质量管理体系内部审核的实践与系统分析，识别出内部审核策划阶段的关键环节，提出审核范围确定、审核计划和抽样方案制订的质量控制要求，为有序高效地实施内部审核提供了技术方法。     

Estimation of uncertainty of sampling for analysis of pesticide residues

Abstract

A computer model was used to take random samples from primary sample populations obtained from field trials to simulate the uncertainty of sampling for residue analysis of plant commodities and soil. The results indicate about 40%, 30% and 20% relative uncertainty when random samples of size 5, 10 and 25 are taken respectively, from a single lot. Therefore the sample size should be the same for establishing and enforcing legal limits.     

扬中生态环境建设的思考与实践

结合扬中生态环境的基本情况和存在的不足，进行了具体分析，对扬中未来生态建设的发展方向提出了建议及实施措施。     

实验室质量管理体系内部审核的实施

在实施ISO／IEC17025：1999标准《检测和校准实验室能力的通用要求》过程中，通过实验室质量管理体系内部审核的实践与系统分析，识别出内部审核实施阶段的关键环节，提出召开首次会议、收集审核证据、确定审核发现和召开末次会议的技术方法，对提高内部审核的质量和有效性、获得可靠的审核结论具有重要意义。