Influence of Soil pH, Organic Matter, and Clay Content on Environmentally Available Lead in Soils: A Case Study in Muncie, Indiana, USA

Due to historical and ongoing industrial practices, lead contamination in urban soils presents substantial health risks, primarily due to its capacity to readily migrate from the soil to humans. This research focused on the influence of soil pH, organic matter, and clay content on extractable lead amounts. Sixty-four soil samples from Muncie, Indiana, were analyzed, revealing that the examined factors accounted for 21.71% of the Pb mg/Kg-dry variable variance (p −0.4, p < 0.001), with XRD and FTIR analyses confirming the binding affinity of clay minerals with lead. In contrast, no significant relationships were found between Pb concentrations and soil pH (r = 0.07;p = 0.59) or organic matter content (r = 0.12;p = 0.34). Elucidating the interactions between lead, clay minerals, and other soil constituents is crucial for addressing lead-contaminated soils and reducing environmental and health impacts.

土壤中Fe(Ⅱ)和全铁的分析方法研究

研究icp-oes测定土壤中Fe(Ⅱ)和全铁的方法,本方法通过DTPA浸提、使用icp-oes测定土壤Fe(Ⅱ)含量,用氢氟酸-高氯酸-硝酸消解、使用icp-oes测定土壤中全铁(以Fe_(2)O_(3)计)的含量,Fe(Ⅲ)通过全铁与Fe(Ⅱ)差减法求得。测得Fe(Ⅱ)的检出限为0.04 mg/kg,相对标准偏差4.9%~7.4%,相对误差5.0%~5.5%;测得全铁的检出限为0.015%,相对标准偏差2.0%~6.2%,相对误差-2.3%~-0.8%。该方法简便,仪器灵敏度高,基体效应较低,质控样测定准确,是测定土壤中Fe(Ⅱ)和全铁比较适用和可行的新方法。

氨基功能化双醛淀粉吸附剂的制备及其对Pb(Ⅱ)的吸附行为

以淀粉为原料,高碘酸钠为氧化剂,制备出双醛淀粉(DAS),然后与水合肼反应制备了氨基功能化双醛淀粉吸附剂(NH_(2)-DAS)。采用扫描电子显微镜、能量色散X射线光谱仪、X射线衍射仪、热重分析仪和X射线光电子能谱等表征手段对NH_(2)-DAS的形貌、元素组成、热稳定性和表面化学性质进行了分析。详细研究了NH_(2)-DAS吸附剂对水溶液中Pb(Ⅱ)离子的吸附行为和吸附机理。结果表明,NH_(2)-DAS对Pb(Ⅱ)的吸附符合Langmuir等温吸附模型和准二级吸附动力学模型。当吸附温度为45℃、pH为5.5、吸附时间为240min时,NH_(2)-DAS对Pb(Ⅱ)的吸附容量达到165mg/g。NH_(2)-DAS对Pb(Ⅱ)的吸附作用主要是利用其表面—C==N—和—NH_(2)与Pb(Ⅱ)的配位螯合作用实现的,且为自发、吸热的熵增过程。经过5次再生利用后,NH_(2)-DAS对Pb(Ⅱ)的吸附容量仍然能达到初始吸附容量的84.8%。该NH_(2)-DAS吸附剂在吸附Pb(Ⅱ)方面具有潜在的应用前景。

羟基磷灰石、粉煤灰对铅(Ⅱ)、镉(Ⅱ)在土壤中迁移的影响

土壤中重金属污染严重威胁着动植物和人类的生存环境,迫切需要廉价且高效的材料和方法来减少其流动和迁移。采用土柱实验,探究羟基磷灰石(HAP)和羟基磷灰石与粉煤灰的混合物(HAP+FA)对污染土壤中的铅、镉重金属的稳定效果。结果表明,土壤pH随着HAP和HAP+FA的加入略微升高;渗滤液中重金属的浓度呈现出CK(不加稳定剂)>HAP+FA>HAP;经过稳定剂处理后的土壤中重金属迁移性均低于未经稳定剂处理的,其中初始浓度为400,800 mg/kg铅污染土壤,HAP比HAP+FA的稳定效率分别高出7.5%,2.79%,对于初始浓度为400,800 mg/kg镉污染土壤,HAP比HAP+FA的稳定效率分别高出2.5%和0.51%。HAP对铅和镉的稳定效率均高于HAP+FA,且等量的稳定剂对同等浓度铅的稳定效率更高。

Adsorption and desorption of Cu(Ⅱ) and Pb(Ⅱ) in paddy soils cultivated for various years in the subtropical China

The adsorption and desorption of Cu（Ⅱ） and Pb（Ⅱ） on upland red soil,and paddy soils which were originated from the upland soil and cultivated for 8,15,35 and 85 years,were investigated using the batch method.The study showed that the organic matter content and cation exchange capacity （CEC） of the soils are important factors controlling the adsorption and desorption of Cu（Ⅱ） and Pb（Ⅱ）.The 15-Year paddy soil had the highest adsorption capacity for Pb（Ⅱ）,followed by the 35-Year paddy soil.Both the 35-Year paddy soil and 15-Year paddy soil adsorbed more Cu（Ⅱ） than the upland soil and other paddy soils.The 15-Year paddy soils exhibited the highest desorption percentage for both Cu（Ⅱ） and Pb（Ⅱ）.These results are consistent with the trend for the CEC of the soils tested.The high soil CEC contributes not only to the adsorption of Cu（Ⅱ） and Pb（Ⅱ） but also to the electrostatic adsorption of the two heavy metals by the soils.Lower desorption percentages for Cu（Ⅱ） （36.7% to 42.2%） and Pb（Ⅱ） （50.4% to 57.9%） were observed for the 85-Year paddy soil.The highest content of organic matter in the soil was responsible for the low desorption percentages for the two metals because the formation of the complexes between the organic matter and the metals could increase the stability of the heavy metals in the soils.

Field demonstration of reduction of lead availability in soil and cabbage (Brassica Chinensis L.) contaminated by mining tailings using phosphorus fertilizers

A field demonstration of reduction of lead availability in a soil and cabbage (Brassica Chinensis L.) contaminated by mining tailings, located in Shaoxing, China was carried out to evaluate the effects of applications of phosphorus fertilizers on Pb fractionation and Pb phytoavailability in the soil. It was found that the addition of all three P fertilizers including single super phosphate (SSP), phosphate rock (PR), and calcium magnesium phosphate (CMP) significantly decreased the percentage of water-soluble and exchangeable (WE) soil Pb and then reduced the uptake of Pb, Cd, and Zn by the cabbage compared to the control (CK). The results showed that the level of 300 g P/m2 soil was the most cost-effective application rate of P fertilizers for reducing Pb availability at the first stage of remediation, and that at this P level, the effect of WE fraction of Pb in the soil de- creased by three phosphorus fertilizers followed the order: CMP (79%)>SSP (41%)>PR (23%); Effectiveness on the reduction of Pb uptake by cabbage was in the order: CMP (53%)>SSP (41%)>PR (30%). Therefore our field trial demonstrated that it was effective and feasible to reduce Pb availability in soil and cabbage contaminated by mining tailings using P fertilizers in China and PR would be a most cost-effective amendment.

Phosphorus utilization and microbial community in response to lead/iron addition to a waterlogged soil

Constructed wetlands have emerged as a viable option for helping to solve a wide range of water quality problems. However, heavy metals adsorbed by substrates would decrease the growth of plants, impair the functions of wetlands and eventually result in a failure of contaminant removal. Typha latifolia L., tolerant to heavy metals, has been widely used for phytoremediation of Pb/Zn mine tailings under waterlogged conditions. This study examined effects of iron as ferrous sulfate （100 and 500 mg/kg） and lead as lead nitrate （0, 100, 500 and 1000 mg/kg） on phosphorus utilization and microbial community structure in a constructed wetland. Wetland plants （T. latifolia） were grown for 8 weeks in rhizobags filled with a paddy soil under waterlogged conditions. The results showed that both the amount of iron plaque on the roots and phosphorus adsorbed on the plaque decreased with the amount of lead addition. When the ratio of added iron to lead was 1：1, phosphorus utilized by plants was the maximum. Total amount of phospholipids fatty acids （PLFAs） was 23%-59% higher in the rhizosphere soil than in bulk soil. The relative abundance of Gram-negative bacteria, aerobic bacteria, and methane oxidizing bacteria was also higher in the rhizosphere soil than in bulk soil, but opposite was observed for other bacteria and fungi. Based on cluster analysis, microbial communities were mostly controlled by the addition of ferrous sulfate and lead nitrate in rhizosphere and bulk soil, respectively.

Lead content of urban soils in China

This paper presents the background value of Pb content in soils from Wuhan,Lanzhou,Changchun andQingdao cities in China,the soils were contaminated by either of smelter,automo- bile,chemical industries,and traffic road. The degree of Pb pollution in the four cities is different,Wuhan >Qingdao > Changchun>Lanzhou. The heavier pollution is where it is nearer to the pollution source. The Pb pollution in Wuhan,Qingdao and Changchun is similar to that of Ber- mingham.

Lead Accumulation in Surface Soils and Components of Balenites Aegyptica Specie in a Katsina Urban Area, Nigeria

The main objective of this paper is to assess the impact of various vehicular traffic densities on lead (Pb) accumulations in some environmental components in Katsina, a semi-arid urban area of Nigeria. Methods This was achieved by collecting and analyzing samples of surface soils, fruits, kernels, leaves, and barks of Balenites aegyptica from locations of different vehicular traffic densities in the area, and analyzing them for lead, using atomic absorption spectrophotometry. Results The results obtained revealed that the Pb concentration in the high, medium, low, and zero traffic density areas are, 75, 53, 35, and 12 μg·g-1 respectively for the fruit pulp. They are also16, 13, 8, and 6 μg·g-1 for fruit kernel and 44, 28, 17, and 9μg·g-1 respectively for leaves. For tree barks, the values are 138, 97, 64, and 18 μg·g-1 respectively while for under-tree-canopy soil samples the mean values are 99, 74, 44, and 17 μg·g-1. In the case of outside-canopy soil samples, the mean values are 113, 91, 50, and 18 μg·g-1 respectively for the various classes of vehicular traffic density. Conclusion These results indicate a strong influence of vehicular traffic density on Pb emission into surrounding atmosphere and its subsequent precipitation on soil and components of B. aegyptica specie in the area. Of all the samples, tree bark should be the best index of assessing Pb pollution in the area, as it maintains the closest contact with the surrounding atmosphere. Since Pb has no known lower limit for human tolerance, there is an urgent need for Pb pollution control in the area to be effectively enforced.

Effect of acetate on lead toxicity to microbial biomass in a red soil

A laboratory incubation experiment was conducted to elucidate the effect of acetate on lead bioavailability and toxicity to microbial biomass in a red soil. Results indicated that the application of acetate along or at the lower lead levels of 100 and 200 μg/g soil stimulated the soil microbial biomass. The addition of acetate at the higher lead levels of 300, 450 and 600 μg/g soil caused significantly greater reductions in the biomass carbon(C mic ) and the biomass nitrogen (N mic ), compared with the control or the same lead levels applied individually. A greater increase in the biomass C:N ratio occurred by acetate addition at the same lead levels. The concentration of 0.01 mol/L CaCl 2 extractable lead was considerably higher in the lead plus acetate treatments than at the same lead levels with no acetate. Based on these results, it was concluded that the application of acetate might have suppressed the lead adsorption in the soil which in turn resulted in its more bioavailability and hence more toxicity to the soil microbial biomass.

Toxicity threshold of lead(Pb) to nitrifying microorganisms in soils determined by substrate-induced nitrification assay and prediction model

Lead （Pb） contamination has often been recorded in Chinese field soils. In recent years, efforts have been made to inves- tigate Pb toxicity thresholds in soils with plant growth and microbial assays. However, the influence of soil properties on Pb toxicity impacts on soil microbial processes is poorly understood. In this study ten soils with different properties were collected in China to investigate the relationships between thresholds of Pb toxicity to soil microbes and soil properties. The effect of soil leaching on Pb toxicity was also investigated to determine the possible influence of added anions on Pb toxicity during dose-response tests. Toxicity was inferred by measuring substrate-induced nitrification in leached and non-leached soils after Pb addition. We found that soil microbe Pb toxicity thresholds （ECx, x=10, 50） differed significantly between the soils; the 10% inhibition ratio values （ECI0） ranged from 86 to 218 mg kg-1 in non-leached soils and from 101 to 313 mg kg in leached soils. The 50% inhibition ratio values （EC50） ranged from 403 to 969 mg kg^-1 in non-leached soils and from 494 to 1 603 mg kg^-1 in leached soils. Soil leaching increased EC50 and EC50 values by an average leaching factor （LF） of 1.46 and 1.33, respectively. Stepwise multiple regression models predicting Pb toxicity to soil microbes were developed based on ECx and soil properties. Based on these models, soil pH and organic carbon are the most important soil properties af- fecting Pb toxicity thresholds （R2〉0.60）. The quantitative relationship between Pb toxicity and soil properties will be helpful for developing soil-specific guidance on Pb toxicity thresholds in Chinese field soils.

Effects of Cadmium, Lead, and Zinc on Size of MicrobialBiomass in Red Soil

A laboratory incubation experiment was conducted to study the influence of cadmium (Cd), lead (Pb)and zinc (Zn) on the size of the microbial biomass in red soil. All the three metals were applied, separately,at five different levels that were: Cd at 5, 15, 30, 60 and 100 μg g-1; Pb at 100, 200, 300, 450 and 600 μg g-1 and Zn at 50, 100, 150, 200 and 250 μg g-1 soil. In comparison to uncontaminated soil, the microbial biomass carbon and biomass nitrogen decreased sharply in soils contaminated with Cd, Ph and Zn. A more considerable increase in the microbial biomass C: N ratio was observed in the metal contaminated soils than the non-treated control. Among the tested metals, Cd displayed the greatest biocidal effect followed by Zn and Pb, showing their relative toxicity in the order of Cd > Zn > Pb.

Studies on Lead(Ⅱ) Complexes of Ferrocenylaldehyde Aroylhydrazones

The complexes of four ferrocenylaldehyde aroylhydrazones with lead(Ⅱ) were synthesized and characterized. Their compositions, bonding forms and properties were researched by means of elemental analysis, IR, UV Vis, 1H NMR spectra, thermal analysis and molar conductance. The free ligands which existed in the keto form coordinated to lead(Ⅱ) in the enol form to form neutral complexes. The molar ratio of the ligand to lead(Ⅱ) is 2∶1 and the thermal stability of the complex is higher than that of the corresponding ligand because of the formation of the stable chelate ring. The ligands and the complexes are all non electrolytes.

Syntheses, Crystal Structures, and Properties of a New Lead(Ⅱ) Complex Involving Holo-and Hemidirected Coordination Spheres with 3,5,6-Tris(2-pyridyl)-1,2,4-triazine Ligand

[Pb（TPT）（μ-I）2PbI2（μ-I）2Pb（TPT）] 1 （TPT is the abbreviation of 3,5,6-tris（2- pyridyl）-1,2,4-triazine ligand） has been synthesized and characterized by elemental analysis, IR, J H- NMR spectroscopy and studied by thermal and electrochemical properties as well as X-ray crystallography. The single-crystal X-ray data show two different kinds of Pb2＋ ions in 1 with coordination numbers of six, Pbl = PbI6, and five, Pb2 = PbN312, with holodirected and hemidirected coordination spheres, respectively. The supramolecular features in 1 are negotiated through the weak but directional Pb...I, C-H...N and C-H...I interactions and aromatic π-π stacking interactions.

Effect of Lead-Zinc Interaction on Size of Microbial Biomass in Red Soil

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Multivariate optimization of high removal of lead(Ⅱ) using an efficient synthesized Ni-based metal-organic framework adsorbent

A new metal-organic framework(MOF) with the chemical formula of [Ni_(2) F_2(4,4'-Bipy)_(2)(H_(2) O)_(2)](VO_(3))_(2)·8 H_(2) O was introduced to adsorb Pb(Ⅱ) with the highest capacity.The sorbent was characterized by thermogravimetric analysis(TGA),infrared spectroscopy(FT-IR),field-emission scanning electron microscopy(FESEM),energy-dispersive Xray(EDX),and elemental analysis.The optimum conditions were obtained by a face-centered central composite design(FCCD) as follows:adsorbent dosage(m)=1.2 mg, initial concentration of Pb(Ⅱ)(C)=390 mg·L^(-1),and pH=5.According to the Langmuir model(R~2=0.9999),the maximum monolayer uptake capacity of lead(Ⅱ) is 2400.7 mg·g^(-1),which is the highe st observed amount for lead(Ⅱ) adsorption.Neither of the old adsorbents for lead(Ⅱ)has the uptake capacity over 2000 mg·g^(-1).The model of pseudo-second-order describes well the process kinetics.The adsorption process of lead(Ⅱ) is independent of temperature changes.This compound can adsorb lead(Ⅱ) from tap water.In addition to introducing a new MOF with the highest uptake capacity for removal of Pb(Ⅱ) that is the outright novelty of this study,the concurrent modeling of both the removal percent(R) and the uptake capacity(q) is another important advantage.Because it achieves the more economical and favorable optimum conditions in comparison with the single optimization of each response.

Solvothermal Synthesis,Crystal Structure and Luminescent Property of a Two-dimensional Lead(Ⅱ) Compound：[Pb(bmzbc)2]n

A two-dimensional coordination polymer, [Pb（bmzbc）2]n（1）（Hbmzbc =4-benzimidazole-1-yl-benzoic acid）, has been synthesized by the solvothermal reaction of Pb（NO3）2 with Hbmzbc at 120 ℃ in ethanol solvent. Compound 1 has been characterized by single-crystal X-ray diffraction, powder X-ray diffraction, thermogravimetry analysis, and IR spectrum. Compound 1 crystallizes in the orthorhombic system, space group Pccn, with a = 12.5801（7）, b = 20.0795（11）, c = 9.1830（6） ？, V = 2319.6（2） A^3, Z = 4, C（28）H（18）N4O4Pb, Mr = 681.65, Dc = 1.952 g/cm^3, μ = 7.319 mm^-1, F（000） = 1312, the final R = 0.0336 and wR = 0.0965 for 1699 observed reflection with I 〉 2σ（I）. In 1, the bmzbc^– ligands bridge the Pb（Ⅱ） ions to generate a 2-D sheet with（4, 4） topology. The complex exhibits turquoise photoluminescent emission with a maximum at 480 nm upon excitation at 300 nm.

Solvothermal Synthesis,Crystal Structure and Photoluminescence Property of a 3D Lead(Ⅱ)Coordination Polymer Based on Terephthalic Acid

Solvothermal reaction of Pb（NO3）2·6H2O with rigid linear ligand terephthalic acid（H2pta） in N,N-dimethylformamide（DMF） produced a new three-dimensional（3D） lead（Ⅱ）coordination polymer[Pb2（pta）1.5（μ4-OH）（DMF）]n 1,and its structure was characterized by single-crystal X-ray diffraction analyses.In polymer 1,the μ4-OH bridges the nearby lead（Ⅱ） ions into an infinite one-dimensional（1D） chain,and then the organic ligand pta^2- joins the neighbored chains into a 3D structure by two similar connection modes in different configurations.The solid-state photoluminescent studies revealed that 1 exhibits a strong greenish emission mainly originating from ligand-to-metal charge transfer between the delocalized π bonds of the aromatic carboxylate ligand pta^2- and the p orbitals of the Pb^2＋ centers.

Study on soil heavy metals contamination of a lead refinery

The contents of Pb, Cd, Cr, As, and Hg was investigated in the neighboring areas of a lead smelting enterprise and the metals contamination of soil was evaluated with the methodologies of the single factor index and Nemerow integrated index. It is found that the content of heavy metals in the neighboring areas has no obvious difference from the reference points. And the soil contamination of heavy metals varies by elements, the contamination index follows the pollution order: Cd>Hg>Cr>As>Pb. The pollution degree of Cd is at high level and Hg at low level, but Cr and As reached the warning level. Therefore, the lead smelting enterprises should not only control lead but also other heavy metals as Cd.

Heavy metal concentrations in soils and plants in the vicinity of Arufu lead-zinc mine, Middle Benue Trough, Nigeria

This study focused on the influence of base metal mining on heavy metal levels in soils and plants in the vicinity of Arufu lead-zinc mine, Nigeria. Soil samples (0-15 cm depth) and plant samples were collected from cul-tivated farmlands in and around the mine, the unmineralized site and a nearby forest (the control site). The samples were analyzed for heavy metals (Fe, Zn, Mn, Cu, Pb, Cr and Cd) by Atomic Absorption Spectrophotometry (AAS). The physical properties of soils (pH and LOI) were also measured. Results showed that soils from cultivated farm-lands have neutral pH values (6.5-7.5), and low organic matter contents (<10%). Levels of Zn, Pb and Cd in culti-vated soils were higher than the concentrations obtained from the control site. These heavy metals are most probably sourced from mining and agricultural activities in the study area. Heavy metal concentrations measured in plant parts decreased in the order of rice leaves>cassava tubers>peelings. In the same plant species, metal levels decreased in the order of Zn>Fe>Mn>Cu>Pb>Cr>Cd. Most heavy metals were found in plant parts at average concentrations normally observed in plants grown in uncontaminated soil, however, elevated concentrations of Pb and Cd were found in a few cassava samples close to the mine dump. A stepwise linear regression analysis identified soil metal contents, pH and LOI as some of the factors influencing soil-plant metal uptake.