Lead Distribution and Mobility in a Soil Embankment Used as a Bullet Stop at a Shooting Range

The distribution of lead in and below a soil embankment used as a stop butt for lead bullets at a sport shooting range for more than 30 years was investigated. A vertical profile, just behind the shooting target, was mapped by 54 soil samples characterized by contents of lead bullets, soil lead, and easily leachable lead as measured in a leaching test (L/S 2). At the target, the soil contained up to 40% metallic lead and 5 to 10% lead associated with the soil particles (<2?mm). The leaching test showed concentrations of dissolved lead in the range 5 to 20?mg/l. However, in the bottom of the stop butt (about 1?m lower than the target) soil lead was only slightly elevated, and no increase in lead was found below the stop butt in the original soil profile. In the lower part of the stop butt, pH was around 5, which is considered to favor lead migration, but in the soil samples with lead bullets present pH was between 6 and 7. The elevated pH values, probably caused by the corrosion of lead bullets, may have been a significant factor in limiting the migration of lead in the stop butt. The investigation showed that the lead in the stop butt did not affect the surroundings, but that the high lead content of the soil would require that this be treated as waste if the facility was abandoned.     

Changes in winter snow depth affects photosynthesis and physiological characteristics of biological soil crusts in the Tengger Desert

Water availability is a major limiting factor in desert ecosystems. However, a winter snowfall role in the growth of biological soil crusts is still less investigated. Here, four snow treatments were designed to evaluate the effects of snow depth on photosynthesis and physiological characteristics of biological soil crusts. Results showed that snow strongly affected the chlorophyll fluorescence properties. The increased snow depth led to increased contents of photosynthetic pigments and soluble proteins. However, all biological soil crusts also exhibited a decline in malondialdehyde and soluble sugar contents as snow increased. Results demonstrated that different biological soil crusts exhibited different responses to snow depth treatment due to differences in their morphological characteristics and microhabitat. In addition, interspecies differentiation in response to snow depth treatment might affect the survival of some biological soil crusts. Further, this influence might lead to changes in the structural composition and functional communities of biological soil crusts.

     

Microbial strategy for potential lead remediation: a review study

The extensive exploitation and usage of lead compounds result in severe lead(II) pollution in water and soil environments, even in agricultural land, threatening the health of animals and humans via food chains. The recovery and remediation of lead(II) from water and soil environments have been intensively concerned in recent years. Compared with the traditional physic-chemistry treatment, microbial remediation strategy is a promising alternative to remediate lead(II)-contaminated environments due to its cost-effective and environmentally-friendly properties. Various microorganisms are capable of removing or immobilizing lead(II) from water and soil environments through bioaccumulation, precipitation or accelerated transformation of lead(II) into a very stable mineral, resulting in significant effects on lead(II) mobility and bioavailability. In the present review, we investigated a wide diversity of lead(II) bioremediation induced by different microbes and its multi-mechanisms. Moreover, we also discussed the progress and limitations, summarized the common rules of lead(II)-microbe interaction, and evaluated the environmental significance of microbes in lead biogeochemistry process. In addition, we further deliberated the feasibility and potential application of microbes in developing cost-effective, eco-friendly bioremediation or long-term management strategy for lead(II) contaminated repositories.     

Risk Analysis of a Farm Area Near a Lead- and Cadmium-Contaminated Industrial Site

The Asua Valley is an area on the outskirts of Bilbao where industry and small farms still coexist despite decades of serious environmental pollution. The present study was carried out to estimate the risk to which the residents of the area are exposed as a result of soil/dust ingestion and consumption of locally grown fresh produce, and, on the basis of this data, to delimit the areas that might require environmental clean-up. The relation between lead and cadmium content in soil and plant samples was assessed by multiple linear regression. The level of soil lead content for proposing intervention was determined by assessing the exposure of young children due to soil ingestion, assuming a “central-estimate” ingestion rate of 110?mg/day. Vegetable sampling was stratified according to the level of cadmium in the soil. The intervention content of cadmium was established as the midpoint of the soil sampling stratum previous to the one registering a vegetable consumption hazard quotient of 1; in this interval the intake reached 57% of the TDI.     

增温对南亚热带季风常绿阔叶林土壤有机碳及其组分的影响

全球变暖是当前全球气候变化的主要现象,影响着陆地生态系统的碳循环。森林土壤是陆地生态系统中最大的碳库,森林土壤有机碳及其不同组分的积累受到气候变暖的影响,许多研究普遍发现短期增温减少土壤有机碳及其活性碳组分,但尚不清楚这种负效应在长期增温下是否仍存在和有机碳组分是否变化。以鼎湖山季风常绿阔叶林为研究对象,采用红外辐射模拟增温,探究长期增温对南亚热带森林土壤有机碳及其组分的影响。2017—2021年的连续增温观测结果表明:与对照相比,在表层土壤中,增温处理下土壤有机碳含量显著增加4.5%,其中土壤重组有机碳库显著降低9.1%,轻组有机碳库显著增加9.8%,易氧化有机碳含量显著增加5.8%,但微生物生物量碳、可溶性有机碳、惰性有机碳和络合态碳含量不变。增温持续时间显著影响土壤有机碳、微生物生物量碳、易氧化有机碳、可溶性有机碳、轻组有机碳库、重组有机碳库、惰性有机碳和络合态碳。增温处理与增温持续时间的交互作用显著影响微生物生物量碳、易氧化有机碳和重组有机碳库,但对土壤有机碳、土壤可溶性有机碳、惰性有机碳、络合态碳和轻组有机碳库无显著影响。综上所述,长期增温背景下南亚热带季风林的土壤有机碳因土壤活性有机碳组分的增加而增加,使总有机碳增加的生物调控作用可能比矿物保护作用强,但减少的惰性碳组分和增加的活性碳组分可能会使土壤有机碳稳定性下降。本研究结果探讨了南亚热带森林表层土壤有机碳及其组分对长期增温的响应,与大多数研究所发现的短期增温使表层土壤有机碳含量减少形成对比,结果可为预测未来该地区土壤碳库的变化特征提供科学依据和理论支持。     

Remediation of lead and cadmium-contaminated soils

The research was designated to study the ability of plants to bio-accumulate, translocate and remove the heavy metals, lead and cadmium from contaminated soil. The herbal plant ryegrass, Lolium multiflorum was investigated as a bio-accumulator plant for these metals. The translocation of these heavy metals in the herbal plant was compared considering root to shoot transport and redistribution of metals in the root and shoot system. The trace metal contents from root and shoot parts were determined using atomic absorption spectrometer. The results showed that the percent of lead and cadmium transferred to ryegrass plant were averaged as 51.39, and 74.57%, respectively, while those remained in the soil were averaged as 48.61 and 25.43% following 60 days of treatment. The soil-plant transfer index in root and shoot system of ryegrass was found to be 0.32 and 0.20 for lead, and 0.50 and 0.25 for cadmium. These findings indicated that the herbal plant ryegrass, Lolium multiflorum is a good accumulator for cadmium than lead. The soil-plant transfer factor (the conc. of heavy metal in plant to the conc. in soil) indicated that the mechanism of soil remedy using the investigated plant is phytoextraction where the amounts of heavy metals transferred by plant roots into the above ground portions were higher than that remained in the soil. The method offers green technology solution for the contamination problem since it is effective technology with minimal impact on the environment and can be easily used for soil remedy.     

Dietary Exposure to Lead and Cadmium in Yugoslavia

Abstract

Lead exposure still represents a matter of health concern especially in Yugoslavia. To assess the exposure of normal urban population to lead and cadmium through food, a preliminary monitoring was performed on a small group of urban population. Lead, cadmium and some essential elements (calcium, zinc, iron, copper and manganese) were analysed in collected duplicate diet samples and compared to similar population in Sweden. We found that dietary exposure to lead and cadmium is similar to other countries although Yugoslav urban population is exposed to much higher concentrations of lead in air than in cities of developed countries, due to high lead in gasoline. However, daily intake of some essential elements was significantly lower.

Also populations living around lead smelters in various parts of Yugoslavia are still exposed to elevated environmental lead and cadmium levels. To assess the exposure of the population living in this area, a cumulative long-term exposure to lead was determined by measuring lead in deciduous teeth. Concentrations of lead and cadmium in vegetables, soil and meals from the same region were also analysed. Values obtained for lead and cadmium in food products grown in exposed and control area were found to be related to respective concentrations of these elements in soil as well as to the distance from the smelter. Meals prepared in this region show the same trend, revealing very high intake particularly of lead.

The influence of nutritional factors, i.e. dietary calcium on lead metabolism, was also studied. Blood lead concentration was determined in two groups of peasant women living in two regions with different dietary calcium intake. Lower blood lead values were found in the higher dietary calcium intake region.     

Water Organic Pollution and Eutrophication Influence Soil Microbial Processes,Increasing Soil Respiration of Estuarine Wetlands: Site Study in Jiuduansha Wetland

Undisturbed natural wetlands are important carbon sinks due to their low soil respiration. When compared with inland alpine wetlands, estuarine wetlands in densely populated areas are subjected to great pressure associated with environmental pollution. However, the effects of water pollution and eutrophication on soil respiration of estuarine and their mechanism have still not been thoroughly investigated. In this study, two representative zones of a tidal wetland located in the upstream and downstream were investigated to determine the effects of water organic pollution and eutrophication on soil respiration of estuarine wetlands and its mechanism. The results showed that eutrophication, which is a result of there being an excess of nutrients including nitrogen and phosphorus, and organic pollutants in the water near Shang shoal located upstream were higher than in downstream Xia shoal. Due to the absorption and interception function of shoals, there to be more nitrogen, phosphorus and organic matter in Shang shoal soil than in Xia shoal. Abundant nitrogen, phosphorus and organic carbon input to soil of Shang shoal promoted reproduction and growth of some highly heterotrophic metabolic microorganisms such as β-Proteobacteria, γ-Proteobacteria and Acidobacteria which is not conducive to carbon sequestration. These results imply that the performance of pollutant interception and purification function of estuarine wetlands may weaken their carbon sequestration function to some extent.     

Speciation and Vertical Distribution of Lead and Lead Shot in Soil at a Recreational Firing Range

In this study, the speciation, vertical distribution and soil particle size fractions of lead in soil samples at a recreational firing range was determined. This study was performed to gain a better understanding of how lead shot breaks down at ranges. Both the chemical form of lead and the types of soil particles with which lead is associated are important for understanding not only the mobility and persistence, but also the human and ecological impact of lead at these ranges. Lead as shot gun pellets was found to be the dominant form of lead in soil samples. The highest levels were measured in surface samples located in the “fall zone” of the range. Results indicate shot to be relatively absent below surficial samples. Lead concentrations in soil decreased markedly across a 0–6″ depth profile. Lead carbonates were the dominant non-shot form of lead present at all depths. Water-soluble lead species made up a minor fraction of the non-shot lead present in the samples. Based on soil particle sizes measured, highest concentrations of lead were measured in soil particles passing a 0.075 mm sieve.     

Phytoremediation of arsenic and lead in contaminated soil using Chinese brake ferns (Pteris vittata) and Indian mustard (Brassica juncea)

Field and greenhouse experiments were performed to assess the performance of phytoremediation of arsenic and lead from contaminated soil at an EPA Superfund site (Barber Orchard). Chinese Brake ferns (Pteris vittata) were used to extract arsenic. On average, fern shoot arsenic concentrations were as high as 20 times the soil arsenic concentrations under field conditions. It was estimated that 8 years would be required to reduce the acid-extractable portion of soil arsenic to safe levels (40 mg/kg). The effect of soil pH on arsenic extraction was also investigated. Results indicate that increasing soil pH may improve arsenic removal. Indian mustard plants (Brassica juncea) were used under greenhouse conditions to phytoextract soil lead. EDTA was applied to soil and was found to improve lead extraction. When the EDTA concentration was 10 mmol EDTA/kg soil in soil containing 338 mg Pb/kg soil, mustard plants extracted approximately 32 mg of lead. In conclusion, phytoremediation would be a suitable alternative to conventional remediation techniques, especially for soils that do not require immediate remediation.     

Contribution of lead in soil to children’s lead burden,an update

Abstract

Blood lead levels in children in the USA have dropped dramatically since lead in food, air and drinking water was reduced. In inner cities and older residential areas, increased lead exposure may still be a problem because of dilapidated housing with high lead paint levels. In these areas, at mining sites and around smelters lead levels in soil may be very high. A review of many studies indicates that lead in soil or mine tailings does not make a meaningful contribution to lead absorption by children. The contribution of lead in soil to overall exposure, if any, lies within the variation of the analytical method for blood lead measurements. The results of exposure studies in the pediatric population reviewed in this article do not support exposure predictions for children under 6 years of age based on the US EPA Integrated Exposure Uptake Biokinetic Model (using default parameters or using results obtained with in vitro digestion models). They also do not support predictions based on the percent of solubility of lead in soil (accessibility studies).     

Complex Interaction and Adsorption of Glyphosate and Lead in Soil

Glyphosate [N-(phosphonomethyl)-glycine] is a herbicide widely used in large quantities in agricultural applications. It is also known to form complexes with metal ions, although its influence on metal behavior, such as lead (Pb) in soil, is not well understood. In this study, the adsorption and co-adsorption of Pb and glyphosate were determined on two soils [a red (RS) soil, Udic Ferrisol, and a yellow-brown (YB) soil, Udic Luvisol] of distinctly different chemical characteristics at varying pH conditions. Results indicate that the adsorption of lead and glyphosate strongly depends on soil types: the RS soil, characterized by a relatively high iron/aluminum content but a low pH and organic matter content, shows a much lower adsorption capacity for Pb but a higher sorption for glyphosate than the YB soil. The co-existence of Pb and glyphosate in soils resulted in complex interactions among Pb, glyphosate, Pb-glyphosate complexes, and soil minerals. The presence of glyphosate decreased Pb adsorption on the two soils, which was attributed primarily to the formation of soluble Pb-glyphosate complexes having relatively low affinities to soil surfaces. On the other hand, addition of Pb increased the adsorption of glyphosate on both soils, which was attributed to: (1) a decreased solution pH due to the ion exchange between Pb²⁺ and H⁺ on soil surfaces; and (2) increased sorption sites where Pb was adsorbed and acted as a bridge between glyphosate and the soil. The present study illustrates that the complex interactions among glyphosate, Pb, and soil may have important implications for the mobility and bioavailability of Pb in soil and should thus be considered in future environmental risk assessments.     

上海城市绿化带土壤蜱螨目群落结构与生物指标

通过对上海城市绿化带6种典型环境土壤的调查,研究了城市绿化带土壤蜱螨目和其它小节肢类土壤动物的群落结构及其与土壤环境的关系。结果表明:城市绿化带土壤蜱螨目群落结构特征在很大程度上有别于自然土壤和农业土壤,反映了城市绿化带为一新型生态系统;城市绿化带土壤质量较差,但土壤蜱螨目仍然保持了较高的种类丰富度和密度,是恶劣环境评价的较好指示生物类群;除蜱螨目密度和种类丰富度外,甲螨亚目的无翼类、低等类和中气门亚目的种类丰富度和密度以及中气门亚目雌雄性比对环境变化敏感,且这些指标特征对不同环境土壤质量的评价结果基本一致,是较好的生物指标。     

草甸棕壤汞环境容量研究

土壤环境容量是输入土壤生态系统污染物的最大允许负荷,此时该系统仍保持正常的结构和功能。汞对土壤生态和人体健康的毒性颇大,因此研究其土壤容量具有一定的现实意义和理论价值。 本项研究以土壤生态为中心。根据我们建立的综合指标,即土壤-作物、土壤-微生物、土壤-水体系,确定了草甸棕壤汞的临界含量。运用平衡试验所获的参数计算了汞的年容量和变动容量。     

Using Betula pendula and Telephora caryophyllea for Soil Pollution Assessment

The concentrations of available arsenic, copper, lead, and zinc in the soil, and the concentration of these elements in vegetal tissues were measured. The most common species at the sites were studied. All the species that were analyzed took up pollutants and could indicate polluted soil. However, all the studied species did not fit to map pollution. The birch (Betula pendula) and most of the fungi species had still quite low concentrations in their tissues compared with the available concentrations in the soil. No direct correlation between the pollution content in the soil and in the vegetation tissues could be observed. Specimens of Thlaspi caerulescens were accumulating zinc. Of the four fungi species collected, only Thelephora caryophyllea seemed to accumulate actively in the studied pollutants. Moreover, it was possible to use an arsenic test with the fungi, which is also interesting from the perspective of preliminary assessment of the degree of pollution. A qualitative judgement of the soil pollution is possible by examining the plant material. To obtain a more quantitative and complete mapping, the method has to be developed further and completed with other investigations when vegetation is missing.     

A Novel High Biosorbent of Pb-resistant Bacterium Isolate for the Removal of Hazardous Lead from Alkaline Soil and Water: Biosorption Isotherms In Vivo and Bioremediation Strategy

A novel Pb-resistant bacterium was isolated from aged lead-contaminated alkaline soils, and was identified as Bacillus megaterium via the MIDI protocol. The biosorption isotherms and kinetics of Pb(II) associated with B. megaterium in vivo in the alkaline environment were investigated at the first time. All the batch experiments of biosorption demonstrate that the B. megaterium uptake of lead is pH-dependent, exothermic (ΔH° = ?5224.86 KJ mol^?1), spontaneous, and fits well with the Langmuir isotherm, resulting in different kinetics under different examination temperatures. The maximum biosorption capacity is 503.86 mg g^?1 at optimum conditions, which is much better in comparison to the biosorbent reported at the acidic condition in the literature. The Fourier-transform Infrared spectroscopic analysis of lead-loaded biomass confirms that the biosorption between B. megaterium and lead is the chemical adsorption in vivo. A site test indicates that B. megaterium really increases mobility and bioavailability of lead in Pb-contaminated alkaline soil in terms of chemical fractionation in vivo, which will potentially increase its uptake by hyperaccumulated plants in alkaline soils in arid or semi-arid areas of NW, China. Therefore, the novel isolate of B. megaterium with the highest adsorption capacity is a new promising biosorbent for the lead removal in alkaline water and soil.     

大气-土壤-小麦生态系统中铅的分布和迁移规律研究

研究铅在国道附近大气－土壤－小麦生态系统中的分布及其迁移规律。结果表明,大气中铅浓度与汽车流量成正比,而与风速、温度等相关性不明显;距公路越远,土壤及小麦中铅的含量越高,含是与距离呈一定的匀相关性,５ｍ及６０ｍ为其转折点;铅在土壤中由上上及在小麦体中由根向茎、穗的迁移较小;小麦各器官中铅含量大小依次为根〉叶〉穗〉茎〉籽。叶片、穗尚从大气中直接部分铅。在小麦不同生长阶段中,各器官积累铅量不同,其积累     

Effects of grazing and cultivation on soil patterns and processes in the Paulshoek area of Namaqualand

Soils were sampled at three different sites within the Paulshoek area of the Leliefontein District in Namaqualand, South Africa. At one site the effect of heavy grazing on soil characteristics under shrubs and from open positions was compared to a more lightly grazed area. At this site a diverse shrub community was mostly replaced by a single species, Galenia africana, when overgrazed. In another area the effects of cultivation on soil properties was investigated. At the third site the effect of Galenia shrub size on soil properties was measured.Soils from the Paulshoek area of Namaqualand are generally infertile and very low in arbuscular mycorrhizal propagules. Patterns of nitrogen distribution at the landscape level are a result of nutrient enrichment associated with perennial shrubs. Arbuscular mycorrhizal infectivity, soil moisture and pH are also affected by shrubs. Only species capable of forming arbuscular mycorrhizas support populations of mycorrhizal propagules in their rhizosphere. Differences in plant available phosphorus under some shrubs indicate that processes associated with nutrient cycling are also affected by shrubs. Galenia tended to deplete soil moisture and increase soil pH more than other shrubs.Small stock production results in a depletion of soil nutrients at the landscape scale since larger areas of low nutrient soil develop when shrub density decreases following heavy grazing. Heavy grazing also affects soil properties indirectly through a change in shrub composition. Cultivation resulted in a decrease in soil nitrogen and organic matter, a loss which was still detectable after 20 years of fallow. Zones of nutrient enrichment and higher pH were found where Galenia established in the old field. When soil was sampled under different size Galenia shrubs a positive correlation was found between shrub diameter and nitrogen, available phosphorus and pH indicating that Galenia was capable of establishing patches in the soil with different properties rather than selecting such areas for establishment. Thus, Galenia is able to maintain soil patterns typical of Succulent Karoo although it also establishes conditions which probably ensure its success. Individual shrub species also affect soil differently with respect to some components such as mycorrhizas.     

Reduction of Pb and Zn bioavailable forms in metal polluted soils due to paper mill sludge addition. Effects on Pb and Zn transferability to barley

In the last few years solidification/stabilisation of acidic soils polluted by heavy metals with low-cost sorbents has been investigated. Paper mill sludges are produced in large amounts and their disposal is a serious environmental problem. The possibility was therefore studied of using paper mill sludge as a stabilizer to reduce the bioavailable metal forms in polluted soils and thus the transferability of metals to plants (barley). We first investigated the sorbing properties of paper mill sludge for Zn(II) and Pb(II) and then their fractionation both in a polluted soil and in the same soil amended with paper mill sludge in order to check the decrease in mobile forms. Finally in both soils we tested the uptake of two metals by common barley in order to assess the performance of soil remediation from an ecological point of view. The addition of paper mill sludge to a soil contaminated by lead and zinc induces a decrease in the mobile forms of both metals, probably due to the presence in sludge of organic matter and kaolinite, which are able to bind the metals very strongly. The decrease in the mobile forms, which are the most readily available for uptake by plants, corresponds to a decrease in plant uptake.     

Selected Chemical and Physical Properties of Soils and Gut Physiological Processes that Influence Lead Bioavailability

Abstract

This paper considers selected field examples of physical and chemical properties of soil and some of the interactions with gut physiological processes that are related to lead bioavailability. The blood lead response to quantity of lead in mining and milling environments compared with urban and lead smelter conditions appears to be different. The emphasis of this paper is to understand the complexity of the urban environment.

Bioavailability appears to be related to physical and chemical qualities other than mere quantity of lead. Particle size is one physical quality that influences bioavailability. Compared to intact lead—based paint, small particle emissions from vehicles govern the general soil lead pattern in urban environments. Lead has accumulated in soils in proportion to city size, with the inner—city generally measuring the highest lead levels. The soil lead situation is further exacerbated by the chemical influence of other toxic substances such as zinc. In several cities, zinc levels of 1,500 ppm and higher, plus acid conditions (pH 5.4 and lower) have been observed. This condition is phytotoxic to plants and the deficiency of plant cover increases the likelihood for soil lead ingestion. After ingestion, nutritional status becomes an important factor with both iron and calcium deficiencies increasing lead bioavailability.

To complement the other discussions of the Gl tract and bioavailability in this volume, the following physiological responses of the gut that either increase or decrease soil lead bioavailability are described: (1) The role of the ‘normal’ microbial flora in altering baseline gut function, (2) effect of pH, (3) intestinal transit time, (4) role of mucus, and (5) barriers to lead transport. Physiologically there are nine physical and/or chemical barriers to soil lead absorption which tend to decrease bioavailability: any breakdown of or increased permeability in these barriers would have the opposite effect. The addition of a soil amendment, such as pathogen free processed sludge, would be expected to be a practical means for reducing soil lead bioavailability. The amendment should serve to bind lead and thus increase effective particle size. It would also have the benefit of improving plant growth as shown in the laboratory. Further study is needed to conduct toxicity testing and undertake field evaluation.