Feasibility of micro-organisms in soil bioremediation and dust control

Detrimental impacts of dust caused by mine tailings have yielded to several studies on the efficiency of different soil stabilizers.Bacterial stabilization has been recognized as a reality within recent decades,where bacteria could get adhesion to the grains and stabilize the soil particles.However,these bacteria are prone to be destroyed while exposed to the normal environmental conditions.In this study,the effects of microcapsules containing two types of bacterial freeze-dried spores(B.Subtilis Natto LMG 19457 and B.ESH)have been investigated on the mine tailing stability in terms of two parts.The first part of the study is dedicated to the fabrication of microcapsules within the two bacteria and identification of the characteristics of these microcapsules to set the time of microcapsules break and release in the soil.The urea-formaldehyde microcapsules containing tung oil were synthesized using microencapsulation method and at the following,the bacterial spores of B.Subtilis Natto LMG 19457 and B.ESH which had the high durability and the capability to grow in the silicon oil,were added to the microcapsules.The microcapsules effect on MT specimens and the viability of encapsulated spores were determined.The characteristics of the capsules were analyzed by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR)and thermo-gravimetric thermal analysis(TGA).In the second part,wind tunnel tests were conducted to study the effects of microorganism stabilizers on mine tailings.The results indicated that the dust erosion reduced from 16%-using water as a stabilizer-to the 0.2%while using microcapsules containing B.Subtilis Natto LMG 19457 and 0.8%while using microcapsules containing ESH.The results showed the high efficiency of microcapsules containing bacteria in stabilizing the MTs.This phenomenon was proved by SEM imaging in which the voids were bounded significantly while using the bacteria.

Using geoaccumulation index to study source profiles of soil dust in China

Source apportionment studies of TSP （atmospheric particulate matter with aerodynamic diameters ≤ 100 μm） and PM10 （atmospheric particulate matter with aerodynamic diameters ≤ 10 μm） have revealed that soil dust is an important source of these particulates in China. In this study, the contamination of soil dust was assessed through the use of a geoaccumulation index （Igeo）. The mass concentration profiles of 17 elements （Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Ba, and Pb） were established for urban soil dusts. Geochemical compositions of soils from 15 cities were used to represent background urban soil compositions. The results of this study indicated that a number of cities are severely polluted by particulates containing Ca, Cr, Ni, and Cu in both size fractions （TSP and PM10）. Contamination with Zn, Pb, Co, and Br was moderate to severe （Igeo 〉 2）. The Al and Fe concentrations were not high enough for them to be considered contaminants.

Improvement of geotechnical properties of sabkha soil utilizing cement kiln dust

Improvement of properties of weak soils in terms of strength,durability and cost is the key from engineering point of view.The weak soils could be stabilized using mechanical and/or chemical methods.Agents added during chemical stabilization could improve the engineering properties of treated soils.Stabilizers utilized have to satisfy noticeable performance,durability,low price,and can be easily implemented.Since cement kiln dust(CKD) is industrial by-product,it would be a noble task if this waste material could be utilized for stabilization of sabkha soil.This study investigates the feasibility of utilizing CKD for improving the properties of sabkha soil.Soil samples are prepared with 2% cement and 10%,20% or 30% CKD and are tested to determine their unconfined compressive strength(UCS),soaked California bearing ratio(CBR) and durability.Mechanism of stabilization is studied utilizing advanced techniques,such as the scanning electron microscope(SEM),energy dispersive X-ray analysis(EDX),backscattered electron image(BEI) and X-ray diffraction analysis(XRD).It is noted that the sabkha soil mixed with 2% cement and 30% CKD could be used as a sub-base material in rigid pavements.The incorporation of CKD leads to technical and economic benefits.

Effects of dust,soiling,aging,and weather conditions on photovoltaic system performances in a Saharan environment—Case study in Algeria

Solar photovoltaic(PV)power represents one of the most promising future sources of energy in the world.Considered the cleanest form of energy,extensive research is being undertaken to widen its use.Notably,mega projects are being considered for installation in the Middle East and North Africa(MENA)region because of its high solar potential,with hopes of eventually feeding Europe from the PV electricity generated in this region and transported through high voltage direct current(DC)lines.However,current implementation of PV systems has shown that their reliability and efficiency depend upon surrounding environmental factors,such as the ambient temperature,wind,and rainfall,as well as soiling,pollution,and aging.The aim of this study was to investigate,through experimental tests,the effects of such factors on the power output of a grid connected PV station.The results showed that the output power and efficiency are deeply affected by various environmental factors,which are weather dependent.These findings may help us develop appropriate solutions to overcome these drawbacks.

Contribution of Asian dust to soils in Southeast China estimated with Nd and Pb isotopic compositions

Asian dust has been identified in subtropical soils of China.Neodymium(Nd)and lead(Pb)elemental and isotopic geochemistry of soils in Southeast China were used to assess the significance of local versus extraneous sources.The εNd(0)values were close to the parent rocks(+2.9)in the young soils(NSJ);while their values were always negative(〜—3.7)in the old soils(OMJ),implying dust deposition.The young soils contained less Asian dust contribution(<8%)while the old soils contained more than 50%Asian dust contribution.This implied that dust contributions were gradually increasing with the soil development stage and Asian dust input had become the principal Nd source for the old soils in this area.On the other hand,Pb excesses and low 207Pb/206Pb values(〜0.8503)in near-surface soils indicated a significant anthropogenic Pb addition onto surface soils.The close relationship between the Pb content and isotopic ratios in the soil profile indicated that the excessive lead in the surface soil was exogenous.These results suggested that Asian dust made up a significant fraction in the old soils,but that local sources(i.e.,basalt and anthropogenic)were not trivial in Southeast China.

Speciation of heavy metals in airborne particles,road dusts,and soils along expressways in China

This study analyzed the concentrations and chemical forms of Zn,Cu,Pb,Sb,Cd and Mn in airborne particles,road dusts and soils collected along three expressways in Jiangxi Province,China,with different traffic densities,and identified the levels and sources of heavy metal contamination.The concentrations of Zn,Cu,Pb,Sb,and Cd except Mn in airborne particles,road dusts and soils were all in direct proportion to traffic volume.Cd concentrations were low compared with other metals.For instance,the concentrations of Zn,Cu,Pb,Sb,Mn and Cd were 6.6,0.7,2.2,0.1,0.1 and 0.1μg·m-3in PM10along the Changjiu Expressway,792.8,241.4,248.3,9.6,340.5and 8.0 mg·kg-1in road dusts,and 201.1,143.2,59.5,9.5,338.9 and 2.3 mg·kg-1in soils,respectively,but in the case of the ratio of concentration to the environmental background value,most serious contamination was caused by Cd.The sources of the heavy metals were judged by comparisons of the chemical forms of the heavy metals in different environmental media.Pb and Mn in airborne particles were both derived from traffic;Pb in road dusts and soils resulted mainly from the use of leaded gasoline in the past;and Mn in road dusts and soils was derived from parent rocks.Zn,Cu,Sb and Cd in airborne particles,road dusts and soils were derived primarily from traffic,and differences in chemical forms of the heavy metals in different media were due to the interaction between heavy metals in airborne particles and organic matter and other surfaces in road dusts and soils.We also discussed the change of chemical forms of heavy metals in particles of different sizes and under different weather conditions.Bioavailability of heavy metals in airborne particles was much higher than that in road dusts and soils,especially Pb(0.676 in airborne particles,0.159 in road dusts and 0.095 in soils).

Using Poultry Litter Biochar and Rock Dust MB-4 on Release Available Phosphorus to Soils

Highly weathered soils in areas from Brazil are acidic soils, typically characterized by poor fertility, particularly with low soil phosphorus level. This laboratory experiment was carried out to evaluate the influences of biochar, made from the poultry litter and MB-4, rock dust from grinding of silicate rocks in increasing the available soil phosphorus on Ultisol, Oxisol and Entisol. Thus, one experiment involving soils incubation was conducted in laboratory, during 100 days. The treatments consisted of rock powder, MB-4 and poultry litter, biochar, evaluated by the base saturation method, with correction levels from 40% to 80% for Ultisol and Entisol and from 20% to 80% for Oxisol and three replicates. After the incubation period, the soil samples were analyzed in relation to available phosphorus in the soil. The results of this study confirmed that the biochar prepared from the poultry litter through slow pyrolysis was a potential source of phosphorus, particularly to weathered soils. Biochar released phosphorus into the soils. The biochar could be used in the improvement of available phosphorus for the three soils analyzed. During the incubation period, 100 days, the application of increasing doses of MB-4 in soils there was no improvement in the available soil phosphorus. MB-4 was not a source of phosphorus to the soil in a short term.

A Review on Stabilization of Expansive Soil Using Industrial Solid Wastes

In developing countries like India, Industrialization is rising rapidly, and also?a great paucity of land is there, the demand for exploitation of industrial?wastes?which coming from industries is increasing. From geotechnical perspective,?fly ash, granite and quarry waste, cement kiln dust, silica fume, rice husk etc.?are the waste materials?which?have effectual features requisites by an excellent soil stabilization admixture. Stabilization using solid wastes is one of the different?methods of treatment, to improve the engineering properties and make it?suitable for construction. This paper briefs about the recent trends in stabilization of expansive soil using industrial waste (granite and quarry waste, cement kiln?dust, silica fume, rice husk) as stabilizers for decreasing the environmental?hazards.

The Contribution of the GIS and the Principal Component Analysis in the Study of the Cement’s Dusts Impact on the Top Soils in the Central Part of the Oujda-Taourirt Corridor (Eastern Morocco)

Cement dust pollution is one of the sources of atmospheric pollution. The main impacts of the cement activity to the environment are the broadcasts of dusts and gases. The objective of this study is to determine the effects of cement dust pollution on physico-chemical characteristics of the soil at the vicinity of the cement factory in Oujda-Taourirt corridor (Eastern Morocco) using Principal component analysis (PCA) and geographical information system (GIS). Forty one (41) surface soils (0 - 3 cm) were collected from the six rural townships surrounding the cement factory. The collected soil samples were analyzed for their chemical properties (CaO, Al2O3, Fe2O3, K2O, MgO, SO3 and SiO2) as well as their pH and Electric Conductivity. The results of the analysis showed that the dusts emitted by the cement plant are especially basic and contain a high free lime (43.03% CaO). The principal component analysis applied on the 41 superficial soil samples, allows deducting that the free lime and the sulfur oxide are the tracer elements of this form of pollution. Furthermore, the spatial projection of the factor scores of the principal component analysis using the geographical information system permits us to determine the spatial distribution of more polluted areas of soils as well as to estimate their impact at a zone of 2.5 km of beam around the factory.

Utilization of Marble Dust for Improving The Geotechnic Characteristics Of Collapsible Soil

An environment friendly and cost effective factor of collapsible soilstabilization with the help of industrial waste has been widely adoptedin this research. Buildings which are constructed on collapsible soils aresubjected to large deformations and shear failure. Collapsible soil can bebroadly categorized as those soils susceptible to a large reduction in volumeupon wetting. The mechanism usually involved in rapid volume reductionentails breaking of bonds at coarse particle contacts by weakening of finegrainedmaterials brought there by surface tension in evaporating water.This research presents the effects of using marble dust on the geotechnicalproperties of Collapsible soil as a new stabilizing technique. A series ofexperimental tests are carried for samples of collapsing soil with andwithout stabilization using marble dust for dry and soaked conditions.The collapsible soil was mixed with marble dust at different contents of(0, 10, 20, 30%,40% and50%). The results indicated that, The optimumwater content decreases by 20.67% at marble content of 50%, liquidlimit decreses by35.41% at marble content of 50%and frictional angle forsoaked soil decreases by 66.09% at marble content of 50% while un soakedsoil decreases by54.68% at marble content of 50%. The maximum drydensity increases 5.91% at marble content of 50% and cohesion for soakedincreases314.2% at marble content of 50% while un soaked soil increases206.7% at marble content of 50%. It has been found that the adoptedmarble has a good effect in controlling the collapsing potential which isreduced by as much as 64.32% at marble content of 30%.

Transport of atmospheric trace elements and dust－soil to the Western Pacific Ocean

Atmospheric aerosol and rainwater samples collected in the different Western Pacific area were analyzed by instrumental neutron activation and proton induced X-ray emission to (1) determine the atmospheric concentrations of trace elements over the Western Pacific and (2) to esti mate the atmospheric deposition of trace elements and dust-soil material to this region. High abundance of pollutant and crustal elements relative to oceanic sources was observed. Some characteristics of marine atmosphere relating to long-range transport of crustal and anthropogenic elements from continent to the remote ocean are discussed. The total dust-soil particle mass is estimated to be 0. 066-1.2 μg/m￣3 over the Western Pacific Ocean areas. Atmospheric inputs of dust-soil particles control the marine particle concentrations of crustal elements. In addition, the characteristics of marine rain water are discussed.

Electro-Optical Model of Soiling Effects on Photovoltaic Panels and Performance Implications

In this paper,a detailed model of a photovoltaic(PV)panel is used to study the accumulation of dust on solar panels.The presence of dust diminishes the incident light intensity penetrating the panel’s cover glass,as it increases the reflection of light by particles.This phenomenon,commonly known as the“soiling effect”,presents a significant challenge to PV systems on a global scale.Two basic models of the equivalent circuits of a solar cell can be found,namely the single-diode model and the two-diode models.The limitation of efficiency data in manufacturers’datasheets has encouraged us to develop an equivalent electrical model that is efficient under dust conditions,integrated with optical transmittance considerations to investigate the soiling effect.The proposed approach is based on the use of experimental current-voltage(I-V)characteristics with simulated data using MATLAB/Simulink.Our research outcomes underscores the feasibility of accurately quantifying the reduction in energy production resulting from soiling by assessing the optical transmittance of accumulated dust on the surface of PV glass.

Gustiness and Coherent Structure of Strong Winds and Their Role in Dust Emission and Entrainment

After the passage of a cold front, spring in northern China, the outbreak of strong wind is often accompanied by dust emissions. Through analyses of data in the atmospheric boundary layer during a typical case, it is revealed there are rather regular gust wave packets superimposed on the basic strong wind flow. The gust-wind wave packets have a period equal to around 3 6 rains and possess coherent structure. As the vertical transport of momentum is decomposed into separate parts by （a） basic flow, （b） gust-wind, and （c） turbulence, they are all in a downwards direction at the lower levels of the atmospheric boundary layer during strong wind periods. However, （a） is the largest, while （b） and （c） are comparable. All these are very different from the case of normal weather. Besides, the friction velocity at the ground surface is also much larger than that of normal weather and should be corrected by taking the contributions of the basic flow and gust-wind into account.The strong basic flow with descending motion is very favorable for soil erosion and sand/dust emissions, but suppresses the entrainment of dust particles by keeping them within the bottom levels of the atmospheric boundary layer. Owing to the coherent structure of gust-wind, dust particles can effectively overcome the systematic descending air motion and penetrate into the middle and upper levels of the atmospheric boundary layer, and then propagate further and diffuse into the troposphere where ascending air motion prevails.

Element and mineral characterization of dust emission from the saline land at Songnen Plain, Northeastern China

Recent observations of Asian dust storms show an eastern expansion of the source area to degraded lands, where dust emissions have been little studied. The dust concentrations over the saline land of the western Songnen Plain （SSL）, Northeastern China, are circumstantially higher than those from the northwestern Chinese deserts. These concentrations are sensitive to the surface soil conditions and wind velocity on the ground. The dust samples collected during dust storm events on the SSL contain abundant Na, Mg, A1, K, Ca, Fe and Ti, as well as toxic elements such as Cu, V, Zn and Ba. Individual particle analysis reveals that fine saline particles （〈 10 μm in diameter） on the saline land, consisting largely of carbonate, halite and sulfate together with lithogenic minerals such as SiO2 and aluminosilicate, are eventually uplifted during the interval from spring to autuum. The predominantly fine saline particles uplifted from the SSL are likely transported eastward by the winter monsoon circulation and westerlies. Recent degradation of saline lands in Northeastern China would not only increase the frequency of dust storm events in the downwind area, but also might change the chemical composition of the Asian dust emissions.

Soil Development and Fertility Characteristics of Inland Valleys in the Rain Forest Zone of Nigeria: Mineralogical Composition and Particle-Size Distribution

The particle-size distribution and mineralogical composition of the clay （〈 2 μm） and fine-sand （0.25-0.10 mm） fractions in soils of two inland valleys in Abakaliki and Bende, Southeast Nigeria, were investigated to provide basic information on soil-forming processes and agricultural potentials. These soils were silty or clayey, deriving from Cretaceous or Tertiary shale materials. The particle-size distribution and its computation on a clay-free basis revealed relatively remarkable lithologic breaks in a couple of pedons. The effect of lithologic discontinuities on soil mineralogical composition was not, however, conspicuous. Petrographic investigation revealed that quartz predominantly comprised the fine-sand fraction in the soils at both study sites. Nevertheless, the clay mineralogical composition of the soils was a mixture of kaolinite, irregularly interstratified smectite-illite intergrades （S/I）, hydroxyl-A1 interlayered 2：1 type clays （HICs）, vermiculite, smectite, halloysite and illite along with fine-sized quartz in Abakaliki. The soils of Bende predominantly contained smectite, which was partially interlayered with hydroxyl-A1 and kaolinite. It is suggested that seasonal floodwater has slowed the disintegration of weatherable clay minerals inherited from the shale, while quartz originating from the sandstone is predominant in the fine-sand fraction. Additionally, a possible soil-forming process observed at the both study sites was ferrolysis, which was indicated by a clear decreasing pattern of HICs downward in the soil profiles, The entry of S/I and vertical distribution patterns for a couple of clay minerals in the pedon suggested that the soils in Abakaliki have developed under the significant influence of aeolian dust delivered by the Harmattan. The findings might describe a site-specific deposition pattern of Harmattan dusts as well as hydromorphic soil-forming processes in the wetlands of the inland valleys.

Preparation and Characterization of Impurely Irrigated Soil Adsorbent from Beaches

[Objective]We aimed to study the preparation methods of impurely irrigated soil adsorbent from beaches,as well as its ability to absorb phenol.[Method]Using hydrochloric acid as activator,we compared the influences of various soil adsorbents on the adsorption of phenol through the desired orthogonal tests where the usage of saw dust,concentration of hydrochloric acid,liquid-solid ratio and carbonization temperature varied.Afterwards,we characterized this soil adsorbent.[Result]The optimal conditions for preparing the soil adsorbent were as follows,that is,the usage of saw dust was 20%,concentration of HCl was 1 mol /L,the ratio of liquid to solid was 2:1,carbonization temperature was 500 ℃,and activation time was one hour,the absorption efficiency of phenol in water by the soil adsorbent reached above 90%.Characterization showed that the prepared soil adsorbent changed obviously in the structure,that is,soil pores and carbon content increased greatly,as well as its absorption efficiency.[Conclusion]The prepared soil adsorbent by this method greatly improved the absorption efficiency of phenol in water,which provided a novel method for the reasonable utilization of saw dust,with good prospects.

Structural and Physicochemical Properties of Dust and Their Effect on Solar Modules Efficiency in Agadir-Morocco

Experiments of soiling effects on the performances of a PV panel have been performed using dust collected from two sites in the region of Agadir-Morocco.The optical transmittance of the front glass was found to depend on the nature and density of dust.The nature of dust was studied by means of scanning electron microscopy and energy dispersive x-ray spectroscopy.It was found that the granulometry of dust particles depends on the study area.For a dust density of around 20 g/m^(2),the maximum power Pmax of the solar panel decreases drastically from 30 to 20 W for the(HP)site,and no more than 14 W for the(AD)site.The diversity of the behavior of the soiled panel was explained in terms of the size of the particles collected from each area.The transmission of light across the front glass of the PV panel is more affected when the sizes of particles are small.

Does Dust from Arctic Mines Affect Caribou Forage?

This study explores how dust from the Ekati Diamond Mine potentially affects the availability and quality of forage on the seasonal range of the Bathurst caribou herd. Understanding the effects of dust as a source of disturbance is important because the Bathurst caribou population has declined by 93% since the middle 1980s and there are reports that caribou in general may avoid mining projects. There are several challenges for quantifying dust impacts: 1) Natural variations (e.g., topography, natural disturbance, and soil pH) may also impact forage availability and quality for caribou. To minimize their masking effect, we stratified survey sites into seven land cover classes and selected the most populous class (i.e., the dwarf shrub) for assessing the impact. 2) Within class variation (e.g., the proportion of area covered by rocks where vascular plants and lichen do not grow) can further skew the analysis. We eliminated this problem by examining only the area not covered by rocks. 3) Coarse and fine suspended particulates have different spatial coverages, chemical compositions, and pH values. Consequently, their impacts on caribou forage can be different. To distinguish their impacts, we sampled two areas: transects from the Misery Haul Road that has been in active use vs. those from a rarely used spur road outside the Misery Camp. We sampled percent vegetation cover, soil pH, and dust on leaves along these transects during the summers of 2015 and 2016. Our results indicated that the amount of dust on leaves in a zone of ~1000 m from the Misery Haul Road was 3 - 9 times than that of background sites. The zone of reduced lichen percent cover was also about 1000 m. In contrast, these road dust-induced changes in caribou forage were not observed for the dust-free transect from the spur road.

Effect of Dust and Shadow on Performance of Solar Photovoltaic Modules: Experimental Analysis

This study presents an experimental performance of a solar photovoltaic module under clean,dust,and shadow conditions.It is found that there is a significant decrease in electrical power produced(40%in the case of dust panels and 80%in the case of shadow panels)and a decrease in efficiency of around 6%in the case with dust and 9%in the case with the shadow,as compared to the clean panel.From the results,it is clear that there is a substantial effect of a partial shadow than dust on the performance of the solar panel.This is due to the more obstruction of the sunlight by the shadowed area compared to the dust.The dust being finer particles for the given local experimental condition did not influence the panel than the shadow.The main outcome of this study is that the shadowing effect may cause more harm to the PV module than dust for the given experimental conditions.However,Further long-term studies on the effect of dust and shadow are needed to understand the effect on performance degradation and module life.

风流扰动下露天矿土质路面粉尘运移规律研究

为降低露天矿土质路面粉尘质量浓度,提高清洁生产水平,采用气固两相流理论,建立粉尘颗粒起动模型,分析粉尘起动风速及变化规律,利用实验研究进行验证,并确立粉尘运移规律以及运动形式,选取正交实验极差分析各因素对起尘量影响显著性。研究结果表明:粉尘起动风速与粉尘粒径、含水率、负荷均有函数关系;起尘量在粒径、含水率、负荷、风速4种因素下呈现不同变化规律,与粒径、风速均呈非线性关系,与含水率呈负相关,与粉尘负荷呈正相关,影响显著性为:粒径>负荷>风速>含水率;粉尘运动形式与风速和粒径相关,在5 m/s风速下,(0,75]μm粒径粉尘易做悬浮运动,(75,500]μm粒径粉尘易做跳跃运动,(500,1000]μm粒径粉尘易做蠕移运动。研究结果可为降尘措施提供理论指导。