煤基腐殖酸对外源砷胁迫下玉米生长及生理性状的影响

为了筛选用于砷污染土壤治理的煤基腐殖酸，采用盆栽实验研究了施用不同种类和浓度的煤基腐殖酸及EDTA对外源砷胁迫下玉米株高、株鲜重、株干重、根干重、砷积累量、叶片抗氧化酶（POD，SOD和CAT）活性和脯氨酸含量的影响。结果表明，11种供试煤基腐殖酸均促进了玉米生长，提高了叶片POD、SOD和CAT活性。其中6和10号腐殖酸可降低土壤砷活性和显著抑制玉米吸收和积累砷，而8和9号腐殖酸增加了土壤活性砷和显著促进了玉米对砷的吸收和累积，且不同程度地强于EDTA。除8和9号外，其余腐殖酸均可明显降低玉米叶片脯氨酸的含量。EDTA可显著促进玉米吸收和积累砷，且加剧了砷对玉米的危害。因此，8和9号供试煤基腐殖酸可以替代EDTA活化土壤砷，与植物配合以提高砷污染土壤的植物修复速度和效果，而6和10号供试煤基腐殖酸则可用于土壤砷钝化剂，以保证作物产品的安全。     

煤基腐殖酸对外源砷胁迫下玉米生长及生理性状的影响简

为了筛选用于砷污染土壤治理的煤基腐殖酸，采用盆栽实验研究了施用不同种类和浓度的煤基腐殖酸及EDTA对外源砷胁迫下玉米株高、株鲜重、株干重、根干重、砷积累量、叶片抗氧化酶（POD，SOD和CAT）活性和脯氨酸含量的影响。结果表明，11种供试煤基腐殖酸均促进了玉米生长，提高了叶片POD、SOD和CAT活性。其中6和10号腐殖酸可降低土壤砷活性和显著抑制玉米吸收和积累砷，而8和9号腐殖酸增加了土壤活性砷和显著促进了玉米对砷的吸收和累积，且不同程度地强于EDTA。除8和9号外，其余腐殖酸均可明显降低玉米叶片脯氨酸的含量。EDTA可显著促进玉米吸收和积累砷，且加剧了砷对玉米的危害。因此，8和9号供试煤基腐殖酸可以替代EDTA活化土壤砷，与植物配合以提高砷污染土壤的植物修复速度和效果，而6和10号供试煤基腐殖酸则可用于土壤砷钝化剂，以保证作物产品的安全。     

产铁载体菌对龙葵修复土壤Cd污染的促进效应

通过CAS筛选培养基从龙葵根系土中筛选出2株产铁载体菌T1、Y2,经生理生化鉴定和16S r DNA序列分析,初步确定T1、Y2分别为铜绿假单胞菌和阴沟肠杆菌。将2株细菌接种至溶镉溶磷培养基中进行实验室培养,并对溶镉、溶磷结果和2株菌的胞外分泌物进行分析。结果表明,接种T1、Y2菌培养基中的有效镉、有效磷与不接菌对照相比显著增加(P0.05),2株菌分泌的草酸、丁二酸、甘油酸等有机酸使培养基pH显著降低(P0.05),促进了碳酸镉和磷酸钙的活化。在受Cd污染的灌溉土中进行龙葵盆栽实验,以灌根的方式分别接种T1、Y2菌,并对龙葵的生物量、龙葵根系土水溶态Cd浓度、龙葵吸收Cd总量及其根系土壤Cd形态的转化进行分析。结果表明:接种T1、Y2菌处理的龙葵根系土溶液Cd浓度比不接菌对照增加4.5、3.6倍,接种T1菌处理的地上部分与地下部分的干重比不接菌对照增加1.55、2.45倍,接种Y2菌处理的地上部分与地下部分的干重比不接菌对照增加1.47、2.28倍,接种T1、Y2菌处理的龙葵地上部分Cd总吸收量比不接菌对照增加1.56、1.69倍;接种T1、Y2菌处理的龙葵富集系数与未接菌对照相比增加,并没有达到显著性差异(P0.05),接种T1、Y2菌处理的转运系数与未接菌对照相比未显著性变化(P0.05)。接种菌处理有效促进了龙葵根系土壤难溶性形态Cd向可交换态Cd的转化。同时,研究发现接种T1、Y2菌可显著促进(P0.05)龙葵对土壤Cd的吸收,强化了龙葵修复土壤镉污染的能力。     

添加硫酸铁对贵州晴隆老万场污染土壤中砷和锑移动性的影响

添加硫酸铁降低砷的活性从而抑制其在作物中的富集是阻断砷在食物链中传递的重要手段之一。但是,对于砷和锑伴生的复合污染矿区,添加硫酸铁会对锑产生怎样的影响还不清楚。以贵州晴隆老万场砷和锑复合污染土壤为研究对象,通过对土壤中水溶态砷和水溶态锑以及印度芥菜(Brassica juncea L.)、平坝油菜(Brassica juncea var.PBYC)和凯里青油菜(Brassica juncea var.KLQYC)中砷和锑含量的测定,研究了添加3%(质量分数)硫酸铁对土壤中砷和锑移动性的影响。结果表明,种植在未经硫酸铁处理的土壤中的3种作物根系和地上部分干质量分别为0.07～0.12、2.10～2.40g;种植在经硫酸铁处理的土壤中的3种作物根系和地上部分干质量分别为0.11～0.22、4.10～5.70g。与未经硫酸铁处理的土壤相比,经硫酸铁处理的土壤中水溶态砷浓度降低了82%～84%,且作物体中的砷也显著降低,说明硫酸铁能显著降低土壤中的砷活性,有利于作物的生长。然而,经硫酸铁处理的土壤中水溶态锑浓度却比未经硫酸铁处理的土壤增加37%～56%,导致作物中的锑并不下降。因此,添加硫酸铁对砷和锑复合污染土壤而言,虽能钝化土壤中的砷,但是在一定程度上可能增加锑的活性,需考虑锑活化增加引起的风险。     

淡水硅藻的砷甲基化和砷氧化代谢机制

硅藻砷甲基化和氧化过程在淡水生态系统砷生物地球化学循环中发挥重要作用,并且硅藻的重金属抗性与营养元素硅酸盐有效性紧密相关。然而,不同硅藻对无机砷的转化能力和砷抗性差异,硅酸盐对硅藻砷转化的影响机制尚不清楚。选取2种淡水硅藻,即针状菱形藻(Nitzschia acicularis)和谷皮菱形藻(Nitzschia palea),作为研究对象,探究其砷甲基化和氧化作用,以及硅酸盐影响下砷转化和此过程中的相关基因转录活性。结果表明,硅藻暴露于As(Ⅲ)的10 d培养期内主要产生二甲基砷,针状菱形藻的二甲基砷转化率为5.54%,高于谷皮菱形藻的转化率(0.80%)。谷皮菱形藻的As(Ⅲ)氧化作用比针状菱形藻强,前者和后者的氧化率分别为90.1%和3.2%。2种硅藻砷甲基化和氧化能力的差异表明不同硅藻As(Ⅲ)胁迫下的主要砷抗性策略不同。针状菱形藻在As(Ⅲ)胁迫下显著上调砷甲基转移功能基因(arsM)表达,并显著下调硅酸盐转运基因(sit)表达。这表明硅藻驱动胞内砷甲基化反应和减少硅/砷转运活性,从而有助于胞内砷解毒和减少As(Ⅲ)吸收。硅酸盐添加对针状菱形藻的arsM基因表达没有明显影响,但...     

针对含砷硫酸烧渣酸浸液的铁盐沉淀固砷

为考察含砷硫酸烧渣中酸浸脱砷效果和铁盐沉淀固砷行为,采用常温常压酸浸法脱除硫酸烧渣中的砷,并对进入浸出液中的砷以铁盐沉淀的形式脱除,进而对沉淀渣的浸出毒性进行研究。同时,研究了磨矿细度、酸浓度、固液比、浸出时间对硫酸烧渣中砷脱除效率的影响。结果表明,通过控制浸出参数可以将硫酸烧渣中砷的质量分数降低到0.2%以下,通过调节浸出液的pH和Fe/As摩尔比将其中的砷以沉淀的形式脱除。当Fe/As 2、pH=4～6时,溶液中砷浓度降到了0.5 mg·L~(-1)以下。沉淀砷渣主要是以非晶态的形式存在,提高铁砷比有利于提高砷渣稳定性,从而降低浸出毒性。在Fe/As=3、pH=6.04～6.22的条件下,得到的沉淀渣的浸出毒性为0.711 mg·L~(-1)。因此,通过酸浸脱除硫酸烧渣中的砷,进而采用铁盐沉淀的方法能够实现硫酸烧渣中砷的安全处置。     

好氧砷还原菌对吸附态砷迁移转化的影响

利用静态和动态土柱实验初步研究了好氧砷还原菌Bacillus sp.SXB在砷迁移转化过程中的作用。结果表明,在静态实验中,菌株SXB可以有效还原吸附在针铁矿上的五价砷;在动态土柱实验中,由于原土中砷是以三价砷形式存在,因此,不论是空白对照还是菌株SXB加入处理,出水中砷均为三价砷;当孔隙体积大于100时,铁的溶出开始增加。菌株SXB的加入,轻微地促进了土壤中砷的释放,而对铁的释放并没有明显影响。     

菌藻共生体去除废水中砷初探

研究了菌藻共生体对废水中砷的去除效果。研究发现：培养分离所得菌藻共生体中以小球藻为主，此时菌藻共生体积累砷达７．４７ｇ／ｋｇ干重。在引入菌藻共生体并培养１６ｈ后，其对无营养源的含Ａｓ（Ⅲ）、Ａｓ（Ｖ）的废水除砷率达８０％以上，并趋于平衡；含营养源的Ａｓ（Ⅲ）、Ａｓ（Ｖ）的废水中，菌藻共生体对Ａｓ（Ｖ）的去除率大于Ａｓ（Ⅲ），对Ａｓ（Ｖ）去除率超过７０％，但对Ａｓ（Ⅲ）的去除率也在５０％以上，在除砷     

砷胁迫对不同物候期香蒲根系分泌物的影响

为探究典型湿地挺水植物香蒲(Typha angustifolia L.)在砷(As)污染生境中不同物候期的根系分泌物变化特征,测定并分析了A s胁迫下的香蒲根系分泌物构成.结果表明:(1)香蒲根系分泌物主要包括烃类、酚类、生物碱类,枯黄期仅有这3类分泌物,幼苗期还有少量唑类,花果期根系分泌物种类最丰富,出现了特有的有机...     

混凝沉淀法处理含砷选矿废水

某钨矿含砷选矿废水砷含量高且砷以As(V)为主要存在形态,采用混凝沉淀法处理,详细考察了生石灰、硫酸亚铁和六水三氯化铁3种混凝剂对废水中砷的去除效果。实验结果表明,在PAM投加量40 mg/L,静沉时间60 min条件下,比较分析3种混凝剂对砷的去除效果,三氯化铁为最佳除砷混凝剂。三氯化铁最佳除砷工艺条件为:pH 7.5,三氯化铁投加量986.67 mg/L,混凝反应时间25 min,PAM投加量为40 mg/L,静沉60 min,含砷选矿废水经该工艺处理后,砷去除率可达99.14%,出水砷浓度降至0.361 mg/L,达到国家污水综合排放标准(GB8978-1996)。     

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).     

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。     

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     

An application of the theory of kinematics of mixing to the study of tropospheric dispersion

The most common technique used for numerical simulations of tracer mixing is that of the numerical solution of the advection–diffusion equation with the unresolved fluxes parameterized using the similarity theory. Despite correct predictions of the overall directions of transport, models based on a numerical solution of the advection–diffusion equation lack sufficient accuracy to correctly reproduce the coupling of mixing with small scale processes which are sensitive to the microstructure of the tracer distribution. The objective of this paper is to revisit the basic formalism employed in numerical models used to investigate atmospheric tracers. The main mathematical method proposed here is the theory of kinematics of mixing which could be applied effectively for simulations of atmospheric transport processes. At the beginning of the paper, we introduce simple mathematical transformations in order to demonstrate how complex topological structures are created by mixing processes. These idealistic flow systems are essential to explain transport properties of much more complex three-dimensional geophysical flows. An example of the application of the kinematics of mixing to the analysis of tracer transport on a planetary scale is presented in the following sections. The complex filamentary structures simulated in the numerical experiment are evaluated using some commonly applied statistical measures in order to compare the results with the data published in the literature. The results of the experiment are also analysed with the help of simple conceptual models of fluid filaments. The microstructure of the tracer distribution introduced in the paper is essential to increase our understanding of atmospheric transport and to develop more realistic parameterizations of small-scale mixing. The presented results could also be used to improve calculations of the coupling between microphysical processes and tracer mixing.     

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.