Physical effects of dust on leaf physiology of cucumber and kidney bean plants

The physical effects of dust accumulating on leaf surfaces, on leaf physiology, such as photosynthesis, transpiration, stomatal conductance and leaf temperature of cucumber and kidney bean plants were investigated by the use of chemically inert dust. It was found that dust decreased stomatal conductance in the light, and increased it in the dark by plugging the stomata, when the stomata were open during dusting. When dust of smaller particles was applied, the effect was greater. However, the effect was negligible when the stomata were closed during dusting. The dust decreased the photosynthetic rate by shading the leaf surface. The dust of smaller particles had a greater shading effect. Moreover, it was found that the additional absorption of incident radiation by the dust increased the leaf temperature, and consequently changed the photosynthetic rate in accordance with its response curve to leaf temperature. The increase in leaf temperature also increased the transpiration rate.     

Growth, leaf traits and litter decomposition of roadside hybrid aspen (Populus tremula L.× P. tremuloides Michx.) clones

Road traffic contributes considerably to ground-level air pollution and is therefore likely to affect roadside ecosystems. Differences in growth and leaf traits among 13 hybrid aspen (Populus tremula × P. tremuloides) clones were studied in relation to distance from a motorway. The trees sampled were growing 15 and 30 m from a motorway and at a background rural site in southern Finland. Litter decomposition was also measured at both the roadside and rural sites. Height and diameter growth rate and specific leaf area were lowest, and epicuticular wax amount highest in trees growing 15 m from the motorway. Although no significant distance × clone interactions were detected, clone-based analyses indicated differences in genotypic responses to motorway proximity. Leaf N concentration did not differ with distance from the motorway for any of the clones. Leaf litter decomposition was only temporarily retarded in the roadside environment, suggesting minor effects on nutrient cycling.     

Characterization of trace metal particles deposited on some deciduous tree leaves in an urban area

In 1996 and 1997 horse chestnut (Aesculus hippocastanum L.) and Turkish hazel (Corulys colurna L.) leaves were sampled at 2 m height in the Belgrade Botanic Garden, located in an urban area with heavy traffic. Using a scanning electron microscope with an energy dispersive X-ray spectroscopy (SEM-EDAX), the size, size distribution, morphology and chemical composition of individual particles were examined on the adaxial and abaxial surfaces of leaf discs of both species. The majority of particles observed on leaves belonged to a class of fine particles (D < 2 microm). Morphological and chemical composition indicated that the most abundant particles were soot and dust with minor constituents such as Pb, Zn, Ni, V, Cd, Ti, As and Cu. Using an electrochemical technique (DPASV), it was possible to measure trace metal concentrations (Pb, Cu, Zn) in a water-soluble fraction of deposits on each single leaf. Trace metal contents in the leaf deposits, increased during the vegetation period for both species and were considerably higher in A. hippocastanum due to different epidermal characteristics. The higher trace metal concentrations in deposits in 1997 reflected greater atmospheric pollution in the Belgrade urban area.     

Microplastic pollution in deposited urban dust,Tehran metropolis,Iran

Environmental pollutants such as microplastics have become a major concern over the last few decades. We investigated the presence, characteristics, and potential health risks of microplastic dust ingestion. The plastic load of 88 to 605 microplastics per 30 g dry dust with a dominance of black and yellow granule microplastics ranging in size from 250 to 500 μm was determined in 10 street dust samples using a binocular microscope. Fluorescence microscopy was found to be ineffective for detecting and counting plastic debris. Scanning electron microscopy, however, was useful for accurate detection of microplastic particles of different sizes, colors, and shapes (e.g., fiber, spherule, hexagonal, irregular polyhedron). Trace amounts of Al, Na, Ca, Mg, and Si, detected using energy dispersive X-ray spectroscopy, revealed additives of plastic polymers or adsorbed debris on microplastic surfaces. As a first step to estimate the adverse health effects of microplastics in street dust, the frequency of microplastic ingestion per day/year via ingestion of street dust was calculated. Considering exposure during outdoor activities and workspaces with high abundant microplastics as acute exposure, a mean of 3223 and 1063 microplastic particles per year is ingested by children and adults, respectively. Consequently, street dust is a potentially important source of microplastic contamination in the urban environment and control measures are required.     

Dust build-up on surfaces in the indoor environment

The concentration and the composition of dust in the indoor environment has been associated with reported symptoms of the sick building syndrome. Levels of airborne concentrations of dust particles are well known. However, the relation to dust on surfaces for office environments are not well described. In this study, 662 measurements were performed of surface dust concentrations on hard surfaces in 19 buildings within Harvard University based on a sticking gelatine foil method. The measure is the dust covered area of the surface as a percentage. In three offices, the build-up of dust on surfaces was measured for a period of five days. Close to these surfaces the airborne PM_2.5 and PM₁₀ particle mass concentrations were measured simultanously. A significant correlation between the dust build-up and the difference between the PM₁₀ and the PM_2.5 was established. The particle size distribution was measured by means of an Aerodynamic Particle Sizer. The mean dust build-up normalized with the measured PM₁₀ was approximately four times higher than the equivalent calculated by a deposition model. This may in part be due to the effect of preferred orientation when particles settle to a surface. Different data for dust on surfaces and airborne particles in offices were compared. The levels of airborne particles in offices in Europe seem to be higher than the levels in the US.     

Root versus canopy uptake of heavy metals by birch in an industrially polluted area: contrasting behaviour of nickel and copper

We investigated root versus canopy uptake of nickel and copper by mountain birch, Betula pubescens subsp. czerepanovi, close to a nickel-copper smelter on the Kola Peninsula, northwest Russia. To distinguish between aerial contamination of leaf surfaces by dust particles and root-derived contamination of leaves by soluble metals, we transplanted seedlings from a control site to clean and metal-contaminated soils and exposed these seedlings both in clean and polluted sites. Patterns of leaf surface contamination and root uptake were similar for nickel and copper; however, nickel but not copper was effectively translocated from roots to shoots and leaves. The majority (80-95%) of nickel and copper found in birch foliage in the heavily contaminated site was due to deposition of dust particles on leaf surfaces; 32-40% of foliar nickel and 9-19% of foliar copper were in water soluble forms. Washing of fresh leaves removed only a minor part of surface contaminants; boiling of unwashed leaves in distilled water for 15 min removed >90% of soluble nickel and copper.     

Effects of air pollution from road transport on growth and physiology of six transplanted bryophyte species

Motor vehicles emit a cocktail of pollutants; however, little is known about the effects of these pollutants on bryophytes located in roadside habitats. Six bryophyte species were transplanted to either a woodland or a moorland site adjacent to a motorway, and were monitored over seven months from autumn through to spring. All species showed an increase in one or more of the following near the motorway: growth, membrane leakage, chlorophyll concentration, and nitrogen concentration. The strongest effects were observed in the first 50-100 m from the motorway: this was consistent with the nitrogen dioxide pollution profile, which decreased to background levels at a distance of 100-125 m. It is hypothesised that motor vehicle pollution was responsible for the effects observed, and that nitrogen oxides had a key influence. The observed effects may lead to changes in vegetation composition with significant implications for nature conservation and management of roadside sites.     

Dry deposition of airborne sulfate and nitrate to soybeans

Dry deposition contributes a substantial part of the total deposition of acidic pollutants and acid precursors to agricultural systems. However, because of the relative intractability of measurement of dry deposition fluxes, little work has been done to directly quantify dry inputs of pollutants to crops. In this research, foliar surface sampling ('leaf-washing') methods were developed and shown to be a practical and fairly precise means of monitoring the accumulation of dry-deposited SO4(2-) and NO3- on plant surfaces. Leaching of these ions from plant tissues was shown to be negligible; however, uptake by plants (e.g. stomatal gas exchange of SO2 or HNO3 and/or assimilation of surface accumulations of materials) is not accounted for by the sampling method. The significance of dry deposition to modification of the chemical microenvironment of leaf surfaces appears to be a factor of 3 to 20 or more greater than that of wet deposition alone. This is due to the cyclic reactivation of accumulated materials by dew and light rains, which may dissolve and mobilize, but not remove, the pollutant surface deposit. Therefore, while dry deposition of SO2 and SO4(2-) containing particles may contribute only part of the total mass of sulfur inputs to crop systems, the exposure of plant surface tissue to pollutants can be dominated by the dry-deposited material. The alteration of leaf surface chemistry may contribute to possible stress-producing mechanisms such as reduction of cuticular integrity, cellular injury and death, enhanced leaching of primary and secondary metabolites, and changes in pathogen infection efficiency.     

永川城区主要绿化植物的滞尘效应

本文选取重庆市永川区具代表性植物及绿地作为研究对象,采用直接采样和统计分析的方法,对植物单位叶片面积滞尘量进行测定分析。结果表明:同一功能区不同植物种类之间的滞尘能力存在差异,滞尘能力大小排列顺序为:红花檵木>麦冬>小叶榕>红叶石楠>桂花>山茶>女贞>八角金盘>广玉兰>海桐>黄角兰>冬青>银杏>迎春,最高为红花檵木12.361 g/m2,最低为迎春2.0903 g/m2,最大差异达6倍;不同功能区同种植物的平均滞尘量差异显著,排列顺序为:街道绿地>新兴绿地>居住区>净化对照区;运用扫描电镜对叶表进行观察表明:植物的不同叶表结构滞尘能力也有差异,叶片表面被毛、褶皱时滞尘能力较强,叶片光滑或蜡质时滞尘能力较弱;植物叶片滞尘量与植物叶片单片面积呈正相关。     

The effects of coal dust on photosynthetic performance of the mangrove, Avicennia marina in Richards Bay, South Africa

Richards Bay, on the northern KwaZulu-Natal coast, is the largest coal exporting port in South Africa. The coal is stored at the Richards Bay Coal Terminal (RBCT) prior to export. Dust from coal operations is a major problem in the Richards Bay area. In this study, we tested the hypothesis that coal dust adversely affects photosynthetic performance of Avicennia marina (Forssk.) Vierh., the dominant mangrove species in the harbour. Photosynthetic performance was determined on 10 trees by measuring carbon dioxide uptake and chlorophyll fluorescence parameters at two elevation sites and on upper and lower leaf surfaces that were covered or uncovered with coal dust. Measurements were made on five clear, sunny days at saturating light (>1,000 micromol m(-2)s(-1)) and high temperature (28-30 degrees C). Coal dust significantly reduced carbon dioxide exchange of upper and lower leaf surfaces by 17-39%, the reduction being generally greater on the lower leaf surface that is covered by a dense mat of trichomes and salt glands. The reduction in carbon dioxide exchange by coal dust was higher at the high elevation site that supported isolated dwarfed trees. The chlorophyll fluorescence data indicated that leaves coated with dust exhibited significantly lower photosystem II (PS II) quantum yield, lower electron transport rate (ETR) through PSII and reduced quantum efficiency of PSII (FvFm). The chlorophyll fluorescence data supported the gas exchange measurements and are consistent with reduced photosynthetic performance of leaves coated with coal dust.     

Source characterisation of road dust based on chemical and mineralogical composition

Road dust contain potentially toxic pollutants originating from a range of anthropogenic sources common to urban land uses and soil inputs from surrounding areas. The research study analysed the mineralogy and morphology of dust samples from road surfaces from different land uses and background soil samples to characterise the relative source contributions to road dust. The road dust consist primarily of soil derived minerals (60%) with quartz averaging 40-50% and remainder being clay forming minerals of albite, microcline, chlorite and muscovite originating from surrounding soils. About 2% was organic matter primarily originating from plant matter. Potentially toxic pollutants represented about 30% of the build-up. These pollutants consist of brake and tire wear, combustion emissions and fly ash from asphalt. Heavy metals such as Zn, Cu, Pb, Ni, Cr and Cd primarily originate from vehicular traffic while Fe, Al and Mn primarily originate from surrounding soils. The research study confirmed the significant contribution of vehicular traffic to dust deposited on urban road surfaces.     

Assessment of the photochemistry of OH and NO3 on Jeju Island during the Asian-dust-storm period in the spring of 2001

In this study, we examined the influence of the long-range transport of dust particles and air pollutants on the photochemistry of OH and NO3 on Jeju Island, Korea (33.17 degrees N, 126.10 degrees E) during the Asian-dust-storm (ADS) period of April 2001. Three ADS events were observed during the periods of April 10-12, 13-14, and 25-26. Average concentration levels of daytime OH and nighttime NO3 on Jeju Island during the ADS period were estimated to be about 1x10(6) and 2x10(8) moleculescm(-3) ( approximately 9 pptv), respectively. OH levels during the ADS period were lower than those during the non-Asian-dust-storm (NADS) period by a factor of 1.5. This was likely to result from higher CO levels and the significant loading of dust particles, reducing the photolysis frequencies of ozone. Decreases in NO3 levels during the ADS period was likely to be determined mainly by the enhancement of the N2O5 heterogeneous reaction on dust aerosol surfaces. Averaged over 24 h, the reaction between HO2 and NO was the most important source of OH during the study period, followed by ozone photolysis, which contributed more than 95% of the total source. The reactions with CO, NO2, and non-methane hydrocarbons (NMHCs) during the study period were major sinks for OH. The reaction of N2O5 on aerosol surfaces was a more important sink for nighttime NO3 during the ADS due to the significant loading of dust particles. The reaction of NO3 with NMHCs and the gas-phase reaction of N2O5 with water vapor were both significant loss mechanisms during the study period, especially during the NADS. However, dry deposition of these oxidized nitrogen species and a heterogeneous reaction of NO3 were of no importance.     

Effects of inert dust on olive (<Emphasis Type="Italic">Olea europaea</Emphasis> L.) leaf physiological parameters

BACKGROUND: Cement factories are major pollutants for the surrounding areas. Inert dust deposition has been found to affect photosynthesis, stomatal functioning and productivity. Very few studies have been conducted on the effects of cement kiln dust on the physiology of perennial fruit crops. Our goal was to study some cement dust effects on olive leaf physiology.effects on olive leaf physiology. On METHODS: Cement kiln dust has been applied periodically since April 2003 onto olive leaves. Cement dust accumulation and various leaf physiological parameters were evaluated early in July 2003. Measurements were also taken on olive trees close to the cement factory. RESULTS: Leaf dry matter content and specific leaf weight increased with leaf age and dust content. Cement dust decreased leaf total chlorophyll content and chlorophyll a/chlorophyll b ratio. As a result, photosynthetic rate and quantum yield decreased. In addition, transpiration rate slightly decreased, stomatal conductance to H2O and CO2 movement decreased, internal CO2 concentration remained constant and leaf temperature increased. DISCUSSION: The changes in chlorophyll are possibly due to shading and/or photosystem damage. The changes in stomatal functioning were possibly due to dust accumulation between the peltates or othe effects on stomata. CONCLUSIONS: Dust (in this case from a cement kiln) seems to cause substantial changes to leaf physiology, possibly leading to reduced olive productivity. RECOMMENDATIONS: Avoidance of air contamination from cement factories by using available technology should be examined together with any possible methodologies to reduce plant tissue contamination from cement dust. PERSPECTIVES: Longterm effects of dust (from cement kiln or other sources) on olive leaf, plant productivity and nutritional quality of edible parts could be studied for conclusive results on dust contamination effects to perennial crops.     

Technical Manual onSingle Retort Underfeed Stokers

Most of the recent work on the effects of cement-kiln dust has been confined to Germany and results differ considerably. There appears to be little doubt that naturally deposited dust from certain cement plants is responsible for leaf injury to deciduous and coniferous species and occasionally for death of the latter. Injury results from the combination of a relatively thick crust deposit and the toxicity of alkaline solutions formed when dusts are deposited in the presence of free moisture. The results of several hand-dusted field experiments, however, are not so conclusive; dusts are reported as either harmful, harmless, or even indirectly beneficial. In the present laboratory investigation, the comparison of CO₂ exchange in the leaf between dusted and nondusted leaves, as well as occurrence of obvious tissue damage, were used as the criteria of dust effects in short term experiments. The results demonstrated that the finer particles of certain cement-kiln dusts collected from electrostatic precipitators do interfere with CO₂ exchange and in some cases cause considerable leaf injury. The results further suggest that calcium content alone may not be the only indicator of whether a dust might be injurious, and that much more needs to be known about the effects of the interaction of chemical composition, particle size, and deposition rate.     

Deposition and solubility of airborne metals to four plant species grown at varying distances from two heavily trafficked roads in London

In urban areas, a highly variable mixture of pollutants is deposited as particulate matter. The concentration and bioavailability of individual pollutants within particles need to be characterised to ascertain the risks to ecological receptors. This study, carried out at two urban parks, measured the deposition and water-solubility of metals to four species common to UK urban areas. Foliar Cd, Cr, Cu, Fe, Ni, Pb and Zn concentrations were elevated in at least one species compared with those from a rural control site. Concentrations were, however, only affected by distance to road in nettle and, to a lesser extent, birch leaves. Greater concentrations of metal were observed in these species compared to cypress and maple possibly due to differences in plant morphology and leaf surfaces. Solubility appeared to be linked to the size fraction and, therefore, origin of the metal with those present predominantly in the coarse fraction exhibiting low solubility.     

Behavior of particulate matter during high concentration episodes in Seoul

The behavior of particulate matter (PM) during high-concentration episodes was investigated using monitoring data from Guui station, a comprehensive air monitoring station in Seoul, Korea, from January 2008 to March 2010. Five non-Asian dust (ND) episodes and two Asian dust (AD) episodes of high PM concentrations were selected for the study. During the ND episode, primary air pollutants accumulated due to low wind speeds, and PM_2.5 increased along with most other air pollutants. Particles larger than PM_2.5 were also high since these particles were generated by vehicular traffic rather than wind erosion. During strong AD episodes, PM_10–2.5 primarily increased and gaseous primary air pollutants decreased under high wind speeds. However, even during the AD episode, PM_2.5 and gaseous primary air pollutants increased when the effects of AD were weak and wind speeds were low. This study corroborates that accumulation of air pollutants due to a drop in surface wind speed plays an important role in short-term high-concentration occurrences. However, low wind speeds could not be directly linked to local emissions because a significant portion of accumulated air pollutants resulted from long-range transport.     

Emission of respirable dust from stone quarrying,potential health effects,and its management

Mining of minerals exerts adverse pressure on different compartments of environment directly or indirectly. Air is the worst affected environmental matrix, and it can carry the harmful effect of pollutants generated from mining activity even to distant places. The present study was undertaken to estimate the emission of particulate matter (PM_2.5 and PM₁₀) from different activities undertaken in stone quarrying in Mahendragarh, Haryana. The results obtained from the present study indicated that drilling, blasting, crushing, and transport of mined material are chiefly responsible for the generation of dust. Whereas drilling, blasting, and loading were responsible for emission of higher fraction of PM₁₀, crushing and re-suspension of roadside dust from movement of vehicles resulted in generation of relatively higher fraction of finer dust (PM_2.5). Modelling the transport of dust over the Hybrid Single-Particle Lagrangian Integrated Trajectory model revealed that the emitted particle may move up to the distance of about 40 km within 4 h of emission under average meteorological conditions. Fourier transform infrared (FTIR) spectroscopy analysis of dust confirmed the presence of calcite and gypsum, thus confirming the source as mining. The study concluded that generation of PM_2.5-sized particles may impose serious respiratory health effects over the workers engaged in mining, crushing, and transportation of sandstone. Apart from it, population residing downwind of the mining area is particularly vulnerable to the pulmonary effects due to inhalation of dust.

     

Facing Hazardous Matter in Atmospheric Particles with NanoSIMS (2 pp)

Background, Aim and Scope Current scientific studies and evaluations clearly show that an increase of urban dust loads, alone or combined with other pollutants und certain meteorological conditions lead to different significant health effects. Premature death, increased hospital admissions and increased respiratory symptoms and diseases as well as decreased lung function can be observed in combination with high pollutant levels. Sensitive groups like elderly people or children and persons with cardiopulmonary diseases such as asthma are more strongly affected. Because of the direct contact between fine particles and lung tissue more information concerning the surface structure (mapping of toxic elements) is required. Materials and Methods: The NanoSims50 ion microprobe images the element composition at the surface of sub-micrometer air dust particles and documents hot spots of toxic elements as a possible threat for human health. Results: The atmospheric fine dust consists of a complex mixture of organic and inorganic compounds. Heavy metals are fixed on airborn particles in the form of hot spots in a nanometer scale. From a sanitary point of view, the hot spots consisting of toxic elements are particularly relevant as they react directly with the lung tissues. Discussion: To what extent particles can penetrate the various areas of the lungs and be deposited there depends on the one hand on their physical characteristics and on the other on breathing patterns and the anatomy of the lung, which is subject to change as the result of growth, ageing or illness. Once inhaled, some particles can reach the pulmonary alveoli and thus directly expose the lung tissues to toxic elements. Conclusions: Especially the mapping of toxic arsenic or heavy metals like copper on the dust particles shows local hot spots of pollution in the dimension of only 50 nanometers. Recommendations and Perspectives: Imaging of elements in atmospheric particles with NanoSIMS will help to identify the material sources.     

Identification of particles containing chromium and lead in road dust and soakaway sediment by electron probe microanalyser

Individual particles containing Cr and/or Pb and other major components were identified in road dust from a heavily used road (hereinafter 'heavy traffic road dust'), road dust from a residential area and soakaway sediment by electron probe microanalyser to locate their sources and carrier particles. Individual particles containing high levels of Cr and/or Pb (>or=0.2%) were identified using wavelength dispersive spectrometry (WDS) map analysis. Chromium, Pb and other major elements were then determined by means of a combination of WDS and energy-dispersive spectrometry in all identified particles, 50 particles containing neither Cr nor Pb from each type of road dust and soakaway sediment, and yellow road line markings. WDS map analysis revealed that many particles containing both Cr and Pb were present among the identified particles in heavy traffic road dust, whereas they were minor components in road dust from the residential area and soakaway sediment. The plots of X-ray intensities of Cr vs. Pb were linear for the identified particles containing both Cr and Pb in heavy traffic road dust, and the line closely fitted the plots for the three yellow road line marking samples. Individual particles were then classified using cluster analysis of element components. The results revealed that the adsorption of source materials or released metals onto soil minerals occurred in road dust and soakaway sediment, that the yellow road line markings were sources of Cr and Pb in heavy traffic road dust, and that materials containing Fe as a major component, such as stainless steel, were additional sources of Cr in both road dust and soakaway sediment.     

Non-exhaust emission measurement system of the mobile laboratory SNIFFER

In this paper we describe and quality assure the sampling system of a mobile research laboratory SNIFFER which was shown to be a useful tool for studying emission levels of respirable dust from street surfaces. The dust plume had bimodal structure; another mode rising to higher altitudes whereas the other mode remained at lower altitudes. The system was tested on a route in Helsinki, Finland, during spring 2005 and 2006. The PM_2.5 and PM₁₀ were positively correlated and the PM levels increased with the vehicle speed. SNIFFER was able to identify the characteristic emission levels on different streets. A clear downward trend in the concentrations was observed in all street locations between April and June. The composition of the street dust collected by SNIFFER was compared with springtime PM₁₀ aerosol samples from the air quality monitoring stations in Helsinki. The results showed similarities in the abundance and composition of the mineral fraction but contained significantly more salt particles.