Levels of Lead and other Metals in Citrus Alongside a Motor Road

The present study investigates the accumulation of Pb, Cu, Mn and Zn in leaves of Citrus limon (L.) Burm picked up from a field situated near a busy road. Samples were collected at different distances of 1–500 m from the road. Washed and unwashed foliage of citrus were analyzed by AA. Differences between washed and unwashed samples were found only for lead which indicated a significant reduction in concentration in all distances that come up to 52.35%, the differences evidence that this metal mainly reaches leaves by aerial deposition. Lead concentration in leaves of citrus with regard to distance from the roads decreases rapidly with increasing distance. Lead levels were higher than typical background concentrations. These concentrations indicated that lead pollution on a local scale is caused by emissions from motor vehicles that are still using leaded gasoline, that is, the only source of contamination known in this place. The content of the other metals did not present significant differences between washed and unwashed samples and the concentrations are not a function of the distance from the road.     

Lead Accumulation in Quercus Nigra and Q. Velutina near Smelting Facilities in Alabama,U.S.A.

Lead is very toxic and if ingested cancause severe health problems to both animals andhumans. To determine if lead accumulation in treescould provide a direct pathway to enter the foodchain, oaks (Q. nigra or Q. velutina)growing near two lead smelting facilities in Alabama,U.S.A., were analyzed for lead in acorns, leaves and treecores. A relatively pristine site was used as acontrol. Lead was not detected in acorns collected atany site, and was only found in tree cores from thesites near smelters. Significant increases in treecore lead from 1975–1995 were detected at the activesmelter site. Results were different from the inactivesmelter site; lead increased in tree cores until thesmelter ceased operation, then decreased afterclosing. Soil lead decreased linearly with distancefrom both smelters. In addition, a significantpositive relationship was observed between leaf andsoil lead at the site with the active smelter, andmay be the result of both translocation via treeroots, and foliar absorption of deposited lead ionsinto the leaf structure.     

A survey of lead pollution in Baghdad

Lead pollution in Baghdad City was studied. Several potential sources of Pb pollution were investigated, among which are leaded gasoline, battery manufacturing, and printing press type. The study included the analysis of blood samples from males and females of different ages and professions. Particular attention was given to workers who are in direct contact with Pb materials in order to discover whether local contamination is taking place or not. In addition, samples of palm leaves were collected from about twenty five different parts of Baghdad in 1978 and again in 1980 in order to study the distribution and relative increase in Pb deposition caused by vehicles using leaded gasoline. The results were compared with similar samples from less crowded cities. The results of this survey have shown that Pb pollution exists; its scale, however, can not be determined accurately until more data are obtained.     

An Assessment of Mercury in the Form of Amalgam in Dental Wastewater in the United States

An assessment was conducted of the discharge from dental facilities of mercury in the form of amalgam to surface waters in the United States. Two pathways were examined – effluent from publicly owned treatment works (POTWs) and air emissions from sewage sludge incinerators (SSIs). The annual use of mercury in the form of amalgam in the U.S. is approximately 35.2 tons (31.9 metric tons). It was estimated that 29.7 tons (26.9 metric tons) of mercury in the form of amalgam are annually discharged to the internal wastewater systems of dental facilities during amalgam placements and removals. Based on the partial capture of this amalgam in conventional chair-side traps and vacuum filters, the discharge of mercury in the form of amalgam from dental facilities to POTWs was estimated to be 6.5 tons (5.9 metric tons). The discharge of mercury to surface water via POTW effluents and SSI emissions was estimated to total approximately 0.4 tons (0.4 metric tons). A cost-effectiveness analysis determined that the annual cost to the dental industry to reduce mercury discharges through the use of amalgam separators would range from 380 millionto 1.14 billion per ton.     

Biomonitoring of Trace Elements in Air and Soil Compartments Along the Major Motorway in France

The impact on the environment of Cd, Pb and Zn emissions from the A1 motorway, one of the busiest in France, was based on a simultaneous analysis of lichens, fungi and soil.The study was conducted in 12 rest areas located along a 55 kmstretch of the motorway. Cd, Pb and Zn concentrations in the top soil horizon (0–10 cm) largely exceeded their concentrations at the control site.The Cd-, Pb- and Zn levels in fruiting bodies of fungi Armillaria mellea, Coprinus comatus, Marasmius oreades and Paxillus involutus were highly variable between sites. The contamination degree of transplanted thalliof Parmelia caperata was well correlated to the cumulated traffic on the western side. On the eastern side, heavy metals originated from the traffic but also from neighbouring sources (urbanization and agricultural practices). Although lead levels are decreasing, leaded petrol is still on offer and lead remains an indicator of vehicle pollution.     

Compaction by agricultural vehicles: A review III. Incidence and control of compaction in crop production

Modern systems of crop production are tending to increase both the number of passes and the loads carried on the wheels of agricultural vehicles. Therefore, compaction problems may arise, especially in seedbed preparation, spraying and harvesting operations. Because of the difficulty and cost of subsoil cultivation it appears likely that more importance will be attached to the avoidance of subsoil compaction since there is widespread evidence that such compaction may persist for many years even when deep freezing is a regular occurrence in winter.Compaction from wheel traffic has often been found to influence adversely all stages of crop growth, responses being particularly marked in the early phases of establishment. However, in some situations crop responses to compaction are beneficial. In both cases crop responses show marked interaction with weather conditions, particularly water status, during the growing period of the crop.Opportunities exist for reducing the compaction from vehicles. Apart from the combination of field operations to permit fewer wheel passes there would be additional benefits from reductions in load and tyre inflation pressure and by confining some or all traffic to pre-arranged strips for use solely as unplanted wheel tracks (“controlled traffic”). Changes in the demand for traction and in the amounts of applied sprays, amendments and fertilisers may permit a radical departure from current tractor design which could greatly reduce the incidence of compaction problems.The financial disadvantages attributable to the incidence of compaction in crop production are increasingly recognised but quantitative information is rarely sufficient to permit a cost/benefit analysis to be undertaken for those techniques which allow compaction to be avoided rather than ameliorated.     

Farmers' perceptions and concerns: the risks of driving farm vehicles on rural roadways in North Carolina

This study focuses on farmers' perceptions of roadway safety and reviews specific and pertinent North Carolina rural road crash data to evaluate their perceptions and concerns. A survey was mailed to 1,357 prospective participants throughout North Carolina. Of these, 656 (48.3%) North Carolina farmers completed and returned the survey. The study revealed that while the majority of respondents took a number of specific safety measures to ensure their safety while driving their tractor on rural roads, most believed that driving their tractor on rural roads was more dangerous than it was five years ago. Few respondents believed that laws governing tractors on rural roads are well known by urban residents. While a majority of the respondents would support a law to mandate the use of a slow-moving vehicle (SMV) emblem on the back of slow-moving farm equipment, a majority also believed that a more effective way to mitigate potential crashes would be to ensure that all farm vehicles had blinking or flashing lights, that diamond-shaped caution signs depicting a tractor were posted on roadways with frequent tractor traffic, and that roadway shoulders were created or widened on roads with heavy farm traffic so that tractors could move off the roadway. Only 22% of respondents felt safe driving their tractor on rural roadways in North Carolina. Most respondents felt that the biggest problem with roadway safety was the lack of respect and increased speed of other drivers. Recent data indicate that in crashes involving farm vehicles, citations were issued to 34% of the non-farm vehicle operators and 24% to farm vehicle operators. For those driving non-farm vehicle who were deemed at fault, 66% were cited for failure to reduce speed. For those driving farm vehicles, the most frequent citation involved the lack of safe movement.     

Lead Concentrations,Isotope Ratios,and Source Apportionment in Road Deposited Sediments,Honolulu, Oahu,Hawaii

Anthropogenic contributions of lead to the urban environment havebeen dominated by combustion of leaded gasoline. A number of studies have used lead concentrations in road deposited sediments(RDSs) to infer automobile contributions. However, few studies have combined concentration data, enrichment ratios, and lead isotope ratio data into a comprehensive picture of lead contamination of road sediments. An urban, non-industrialized basin, in Oahu, Hawaii, was selected for investigation. Twenty RDSsamples were collected throughout the 11 km² system, with anundisturbed soil profile sampled to a depth of 30 cm to documentbackground lead levels.Median lead concentrations from a weak (cold) HCl digestion and a hot nitric acid digestion were 3 and 7 mg kg^-1 for thebackground soil, and 256 and 303 mg kg^-1 for RDSs. The median Pb enrichment ratio (HCl digestion) for RDSs was 129, witha range from 24 to 883. All the data collected point to a highlycontaminated environment.Lead isotope ratios from potential sources were examined relativeto those observed for RDSs in the system. Host geological rocks,paint, and long-range aerosol transport were ruled-out as significant sources based on an examination of isotope ratios andpotential loadings to road sediments. Leaded gasoline wasidentified as the major contributor to present-day road sedimentsbased on their radiogenic nature, with mean ²⁰⁶Pb/²⁰⁴Pb = 18.787 ± 0.096 (95% confidence interval), ²⁰⁷Pb/²⁰⁴Pb = 15.847± 0.074, ²⁰⁸Pb/²⁰⁴Pb= 38.836 ± 0.221, and ²⁰⁶Pb/²⁰⁷Pb = 1.184 ± 0.009. The contribution of gasoline additives to RDS for two periods, pre-1968 and post-1968, were estimated using ²⁰⁶Pb/²⁰⁷Pb ratios. The average contribution of post-1968 lead to RDSs was 59%, with a range from 32 to 81%. To explain the mixed age of lead in the RDSs, we suggest that erosional processes have mobilized sediment from roadside reservoirs in the basin that have accumulated automobile emissions primarily since the 1930s. The significant shift in useof radiogenic (J-type) ores, mostly from Missouri, USA, have allowed us to fingerprint and apportion lead in RDSs of thissystem.     

Analytical Studies on Lead Pollution in Roadside Soil Samples of Raipur and Bhilai,Chhattisgarh State,India

Abstract

Although lead in gasoline represents only 2.2% of total global lead use, this fuel remains by far the single largest source of this heavy metal in urban areas. In developing countries like India approximately 90% of all lead emissions into the atmosphere are due to the use of leaded gasoline. In many countries in Southeast Asia, unleaded gasoline is scarce, and the maximum allowed lead content might reach or exceed 0.8 ppm per liter. Emissions from the metallurgical operations and the waste incineration are also responsible for the rising levels of lead in the environment. Battery recycling, lead‐glazed pottery, and lead pigments industries are other sources of lead in the environment. In the present work, lead pollution in soil samples from Raipur (capital city) and Bhilai, Chhattisgarh State, India, has been investigated. The lead concentration in the surface soil of Raipur and Bhilai was found in the range of 7.2–84.0 and 9.5–79.7 ppm, respectively. The seasonal and temporal variations in the concentration of metal, its distribution pattern, and trend are discussed as well as the mobility, deposition, and sources of lead in the area. The enrichment factor of lead in the urban soil was found to be very high, depending on the nature of sources.     

Tracing Pollution and its Sources with Isotopes

Naturally occurring isotope systems, such as strontium and lead, are very useful for characterizing sources of pollution and producing background information. The phase-out of lead additives to gasoline in Northern Europe has for example not phased out the lead contamination of the environment. The stable lead isotope method shows the contribution from small local sources to the lead contamination of the Oslo air during a period when the combustion of gasoline, the major source of lead contamination, has been decreasing. Wood combustion for domestic heating is one of these polluting sources in Norway. Strontium analyses show that roadsalt from de-icing of a nearby road is accumulated in the soil surrounding an about 4500 year old rock carving. At rainfall this salt is re-dissolved and drained over the rock carving. The impact from the road is confirmed by lead isotopes. Lead and strontium analysis of teeth show the contribution from industry and traffic on todays humans and the differences in nutrient intake during the Medieval era are compared with today. The isotope signatures of the Medieval teeth also show that a person living along the coast can be distinguished easily from a person living in the central parts of the country, and that the Medieval individual mainly lived on locally produce, while the contemporary person to a great degree lives on industrially manufactured food.     

Lead and zinc levels and chemical fractionation in road-side soils of Caracas,Venezuela

Twenty five soil samples located nearby highways and streets of Caracas, Venezuela were collected and chemical, physical and mineralogical analysis were done to characterize them. The soils have light textures, neutral or slightly alkaline pH, medium to high organic matter content, and all of them have carbonate. Kaolinite and mica were the dominant clay minerals in all soil samples. Lead and Zn were extracted with 1N-₃ to investigate the levels of these polluting heavy metals in these roadside soils. A very high level of Pb was found in the soils (average enrichment factor of 151.4), while Zn levels were much lower (average enrichment factor of 5.25), but still higher than normal soils' levels. These results are indication of strong metal pollution (especially by Pb) of Caracas' roadside soils, due to heavy transit of motor vehicles as well as to the exclusive use of highly leaded gasoline in Venezuela. Nevertheless both metals accumulate only on the surface layers of those soils located within 5 m from the roadside. These facts were taken as evidence of the low vertical and horizontal mobility of the metals, which was mainly attributed to the high pH of the studied soils (between 7.5 and 7.8). Three surface soil samples having high Pb and Zn levels were selected for chemical fractionation by McLaren and Crawford's (1973) methodology. It was found that less than 1% Pb and below 5.5% Zn were in exchangeable form in these soils. Therefore, Pb and Zn are predominantly present in non-exchangeable forms in the studied soils. These non-exchangeable metals tend to become associated with different soils materials. Lead is mainly associated with the organic fraction, as well as to the inorganic and residual fractions, and Zn is mainly associated to the inorganic and residual fractions, and also the iron oxides, being practically absent in the organic fraction.     

Effects of wheel traffic along one side of corn and soybean rows

There is a continuing need for information illustrating the seriousness of the soil compaction problem over a range of soils, climatic, and agronomic conditions and encouraging the adoption of controlled traffic. Compaction from wheel traffic adjacent to crop rows had significant effects on the soil physical conditions in Kokomo silty clay loam (Typic Argiaquoll) and on the corn (Zea mays L.) and soybean (Glycine max L.) yields. Traffic patterns were established to compare rows that had traffic on one side of the row with those that had traffic on neither side. These traffic patterns were followed for planting and spraying operations for a total of five passes. Corn had either no nitrogen fertilizer or adequate fertilizer and soybeans had no fertility variable. Bulk density and cone penetration resistance were significantly higher in the wheel tracks than in the untracked areas at the 0–15- and 15–30-cm depths. With adequate fertilizer, yields of corn and soybeans from rows along wheel tracks were equal to those from untracked areas. With no nitrogen fertilizer, corn yields were significantly lower from rows along wheel tracks.     

步行轮机构原理

介绍一种用于软地面车辆的新型行走机构——步行轮的基本原理,所阐述的步行轮机构的运动学和动力学特点及理论分析结果,可为其开发应用和合理设计提供最基础的理论依据。     

铅同位素比率分析技术在食品污染源解析中的应用

铅是一种有毒有害重金属,可通过膳食、呼吸等途径进入人体,并蓄积达到有害水平.由于食用农产品产地环境不断受到铅的污染,使得"从农田到餐桌"食品供应链在最初环节存在较大的风险,因此土壤、大气等环境介质成为食品铅污染的可能来源.为准确找到污染源并及时切断污染途径,降低危害发生的概率,追溯食品中铅污染物的来源显得尤为重要.铅同...     

Anthropogenic emission of platinum-group elements into the environment

This work represents a summary of our test results over emissions of platinum-group elements (PGE) in soils, which were won in the context of an interdisciplinary research project on ‘ecological future research’ sponsored by the Hessian government. Directly related to this investigation was the time-dependent entry of concentrations of PGE in soils along roadsides, their further rise in control and the investigation of the geochemical behaviour of these metals regarding their solubility and mobility in the soil. Soil samples were taken along the motorways of Frankfurt-Wiesbaden (A66), Frankfurt-Mannheim (A5/A67/A6), and the A3 and A45 in the area of Hanau, and the PGE were examined here. The test results do not leave a doubt that the increased PGE contents in the soils in the direct environment of the motorway are to be attributed to motor vehicles with catalysts. In sections of the soil samples of Hanau, Ir and Ru are also seen to occur beside Pt, Pd and Rh. Since these items are not constituents of the catalyst, their origin is possibly due to emissions from the precious metal-processing industry in Hanau. The highest concentrations of PGE in the soil occur directly at the edge of the motorway and decrease with increasing distance from the motorway. The PGE emissions depend on traffic volume and driving characteristics. Based on Pt concentrations found in soils near roadsides and observed traffic volumes, automotive catalytic converters are estimated to emit an average of 270 ng/km. Currently, the Pt and Rh deposited behave immobile in soils. At present, Pt and Rh from catalytic converters present no danger to the groundwater. Although platinum does not represent an acute danger, due to its low concentrations in the environment at the present, this rise in concentration may necessitate the use of routine checks in the future.     

A model for estimating crop yield losses caused by soil compaction

A computerized empirical model for estimating the crop yield losses caused by machinery-induced soil compaction and the value of various countermeasures is presented, along with some examples of estimations made with it. The model is based mainly on results of Swedish field trials, and predicts the effects of compaction in a tillage system that includes mouldboard ploughing. It is designed for use at farm level and predicts four categories of effects: (1) Effects of recompaction after ploughing. The calculations are based on the wheel track distribution in the field and the relationship between “degree of compactness” of the plough layer and crop yield. (2) Effects of plough layer compaction persisting after ploughing. Crop yield losses are estimated from traffic intensity in Mgkm ha⁻¹ (Mgkm = the product of the weight of a machine and the distance driven), soil moisture content, tyre inflation pressure and clay content. (3) Effects of subsoil compaction. The calculations are similar to those presented under point (2), but only vehicles with high axle load are considered. These effects are the most persistent. (4) Effects of traffic in ley crops. The estimations are based on wheel track distribution, soil moisture content and several other factors.     

Bioaccumulation of Lead, Calcium and Strontium and their Relationships in the Octopus Octopus vulgaris

Octopuses (Octopus vulgaris) landed from commercial fishing were sampled and the concentrations of lead, calcium and strontium, in digestive gland, branchial heart, gills, mantle and arms, were determined using PIXE (particle-induced X-ray emission). Lead was detected in all tissues, although not in samples from all animals analysed. Female octopuses accumulated more lead in digestive gland than did males. The digestive gland index, an indicator of nutritional status, showed a negative correlation with lead concentration in both sexes. There were positive correlations between the concentration of lead and those of calcium and strontium in digestive gland and a negative correlation between lead and calcium in branchial heart tissue. Concentrations of calcium in arms were lower in autumn and spring than in winter and summer. Lead content increased with increasing body weight and mantle length so we can conclude that lead continues to accumulate during the animal’s life. Concentrations of lead in two samples were higher than the maximum legally permitted concentration of lead in food.     

Chemical Partitioning of Heavy Metals in Soils,Clays and Rocks at Historical Lead Smelting Sites

The chemical partitioning of lead and zinc is described in contaminated soils and underlying strata at historical lead smelting sites. Sections of soil-rock cores from eight sites of age 200 to c.1900 yr were analysed using a sequential extraction procedure. Of the total amount of lead and zinc present in soils, only a small proportion is in a readily mobile form. However, this proportion increases significantly as the pH falls below 5 and for lead reaches 37% in soils at Bole A. A high proportion of lead in soils appears to be associated with the carbonate and specifically adsorbed phase. It is suggested that this is partly due to the formation of cerussite (PbCO₃) in soils contaminated with calcareous slag wastes. Lead present in the residual phase in contaminated soils may be related to the presence of the element in silicate slag particles. Rapid migration of lead to a depth of 5.6 m in sandstone at Bole A was related to its high solubility in the acidic soils and rock at this site. Comparable migration at Bole C proceeds by a different mechanism, possibly with lead in association with Fe-Mn oxides and slag particles. In clay infill in fractured sandstone at Bole A, anthropogenic lead present at a depth of 4.4 m was extracted predominantly in the fraction representing Fe-Mn oxides.     

Predicting total soil lead from an acetic acid‐sodium acetate buffered solution

Abstract

Total soil lead was predicted satisfactorily from the Lead extracted by the Standard Morgan soil testing solution (sodium acetate with acetic acid, pH 4.8). Using 161 soils, 85% of the variance in total lead content was accounted for by:

Total Lead = ‐115 + 106.4 √Sodium Acetate Extracted Lead A modified Morgan solution, utilizing EDTA as a chelating agent, extracted greater than 3 times as much lead as the regular Morgan's solution, but was no better in predicting total lead.