High Concentrations Of Pb Research Articles

Phytoremediation Potential of Helianthus annuus L (Sunflower) for the Reclamation of Lead (Pb) Spiked Soil

Soil contamination caused by anthropogenic activities such as industrial activity, excessive waste disposal and natural disasters has become a major problem that endangers human health and the ecosystems. As a low-cost and environmentally friendly remediation method; phytoremediation of polluted soils has attracted a lot of attention. The goal of this study was to screen for the potential of Helianthus annuus L a local plant in the scope area to remediate lead-contaminated soil in a laboratory setting. Phytotolerance of the plant was determined by subjecting the plant to various concentration of Lead (Pb), where 3 kg of pristine soil is spiked with Pb in triplicate in a pots were used for (CR5%=150, CR10%=300, CR15%=450, CR20%=600, CR25%=750 mg) of Pb. The plant gowth is measured for tolerance of lead, Atomic Absorptiob spectrophotometer (AAS) was used determine uptake of lead by the plant samples. The results of phytotolerance of H. annuus show a significant growth of the in lower concentration C5% compared to the control which was not spiked with Pb though there is decrease in the plant growth at high concentration of C25% Pb. The wet and dry biomass of H. annuus in a timeframe of 15 days was analyzed shows significant effect of the heavy metal in the biomass formation. The uptake of Pb by H. annuus was measured using AAS and it show a significant accumulation of Pb in the plant root and very significant in higher concentration of Pb was accumulated and translocated .it is concluded from this study that sunflower plant can absorb and accumulate quantities of lead without affecting the production of biomass indicating the possibility of using it as good candidate in the remediation of Pb polluted soils.

Heavy metal contamination and potential health risks in upland rice-producing soils of rotational shifting cultivation in northern Thailand

Rotational shifting cultivation (RSC) is commonly practiced in northern Thailand for upland rice cultivation, primarily for household consumption. However, the potential health risks from heavy metal contamination in these soils have not been thoroughly explored. This study aimed to evaluate the contamination of six heavy metals (Arsenic (As), Mercury (Hg), Cadmium (Cd), Lead (Pb), Copper (Cu), and Chromium (Cr)) in upland rice across RSC fields with varying fallow periods and assess the associated health risks from rice consumption. Four RSC fields with 5, 6, 10, and 12-year fallow periods were examined. The RSC-6Y and RSC-12Y fields were used for upland rice cultivation in 2022, while the RSC-5Y and RSC-10Y fields were cultivated in 2023. The geo-accumulation index (Igeo) was calculated, and translocation factors (TF) were assessed for the transfer of heavy metals from soil to straw (TFStraw/Soil), straw to grain (TFGrain/Straw), and soil to grain (TFGrain/Soil). The results indicated that after burning vegetation in the RSC fields, the highest concentrations of Pb, Cr, and Hg were found in the ash. In RSC soils, Cu, Cr, As, Pb, and Hg levels were below reference standards, with Cd undetected. In rice grains, the order of concentration was Pb > Cu > Cr > As, with Hg and Cd undetected. Pb levels in rice grains exceeded the safety threshold. Igeo values indicated no contamination to moderate contamination across sites, with negative Igeo values for Cr and Cu, and zero values for Cd. The TF results showed limited transfer of As, Hg, and Cd from soil to rice plants (TFStraw/Soil < 0.1), but notable transfer for Pb, Cr, and Cu. Pb was readily transferred from soil to grain (TFGrain/Soil), posing a potential health risk. The study highlights potential non-carcinogenic and carcinogenic risks from heavy metal exposure, particularly Pb, and underscores the need for further research to determine contamination sources and mitigation strategies.

Interactions between blood lead (Pb) concentration, oxidative stress, cellular immune response and reproductive status in livestock from a mining area

Chronic exposure to lead (Pb) in livestock grazing in abandoned mining areas affects animal welfare and productivity, as well as represents a significant food safety risk. Here, we evaluate the physiological effects of Pb exposure in goats maintained under extensive farming conditions in a non-remediated mining area. We monitored blood, fecal, and milk Pb levels in two groups of goats, pregnant (n=17) and lactating (n=24), kept in different enclosures with high soil Pb concentrations (geometric means of 270 and 143 μg/g, respectively) in Sierra Madrona mining district (Spain). We also studied the influence of Pb exposure on the ability to mount a cellular immune response, and on oxidative stress and biochemical biomarkers measured in blood. Blood Pb concentration was higher in pregnant than in lactating goats, but this difference was not observed in fecal Pb concentration. Pb levels in feces and milk concentrations were correlated with those measured in blood, with 11% of milk samples showing Pb concentrations above the maximum level (ML) for Pb in raw milk established by the EU (0.02 μg/g wet weight). Animals with increased blood Pb levels showed reduced concentrations of retinol in plasma, but these Pb levels did not affect the cellular immune response. The stimulation of the cellular immune response in lactating goats was associated with an increase in blood Pb and calcium (Ca) levels. The reproductive status and age of goats significantly affected several oxidative stress, antioxidants and plasma biochemistry variables. Goats grazing on soils contaminated by past Pb mining activities may be susceptible to detrimental health effects mediated by retinol deficiency. In view of the detected transfer of Pb through milk, special attention should be paid to the food safety of derived products (i.e. cheese).

Coronary artery plaque characteristics in smokers assessed by intracoronary multi-modality imaging: a NIRS-IVUS guided PROSPECT II substudy

Abstract Background Smoking is a risk factor for coronary artery disease and myocardial infarction. Purpose Among patients with myocardial infarction, we hypothesized smokers would have increased prevalence of nonculprit high-risk plaque characteristics as assessed by intracoronary multimodality imaged when compared to nonsmokers. Method This is a prespecified post-hoc analysis of the PROSPECT II (Providing Regional Observations to Study Predictors of Events in the Coronary Tree). Altogether 898 patients with acute myocardial infarction with or without ST-segment elevation who after successful percutaneous coronary intervention had near-infrared spectroscopy and intravascular ultrasound imaging performed. Data on lesion location, plaque burden, and lipid content were collected. Current, former, and nonsmokers were examined regarding the presence of high-risk plaques in both culprit and nonculprit lesions as well as plaque location. High-risk plaque characteristics were defined as a maximum plaque burden (maxPB) of ≥70% and a maximum 4 mm lipid core burden index (maxLCBI4mm) of ≥324.7. Results Out of 886 patients with known smoking history, 32% were smokers, 32% former, and 37% nonsmokers. Smokers were younger (median age: smokers 59.0; former 65.5; nonsmokers 64.0 years, p&amp;lt;0.001) with fewer co-morbidities and presented more often with STEMI (% presenting with STEMI: smokers 22.2%; former 18.9%; nonsmokers 19.4%, p=0.006). LDL was similar but CRP was higher in smokers (median µg/mL: smokers 4.0; former 3.1; nonsmokers 2.9, p=0.004). In multivariate models of nonculprit lesion morphology smoking history was not associated with maxPB or maxLCBI4mm but was associated with presence of calcified nodules (OR: 2.88 (95% CI 1.46–5.69) p=0.002 [smokers vs nonsmokers]). Calcified nodules were also associated with number of years smoked (OR: 1.02 (95% CI 1.01–1.03) p=0.004). Smoking was not associated with presence of ≥1 lesions with MaxLCBI4mm, ≥ 324.7, maxPB &amp;gt;=70% or the combination of both. Smoking was not associated with presence of plaque rupture or thrombus. Right coronary artery culprit lesions were more common in smokers and former smokers (smokers 29.9%; former 30.9%; nonsmokers 21.6%; OR: 1.12 (95% CI 1.04–1.21) p&amp;lt;0.001 [smokers vs nonsmokers]). Conclusion In this prospective intracoronary multimodality imaging study of patients with recent acute myocardial infarction, smoking was not associated with a higher rate of high-risk nonculprit plaques based on lipid content by NIRS or PB by IVUS when compared to former or nonsmokers. However, smoking was associated with higher presence of IVUS-detected calcified nodules, higher CRP-levels, and the right coronary artery as it angiographically was a more common site for culprit lesions. These results indicate that the elevated risk in smokers is unrelated to vulnerable plaque morphology defined by high PB and lipid content, and instead possibly related to inflammation, calcification, or hemodynamic changes.Table 1

Geochemical fractionation of trace elements in ostreid and gastropod shells: A potential proxy for heavy metal pollution in Ghana’s coastal environment

The content of trace elements from Crassostrea tulipa (Ostreidae, Bivalvia) from four localities (Pra Estuary, Densu Estuary, Kpone Beach, and Anyanui Creek) along the coast of Ghana has been used as a bioindicator of environmental pollution. The lowest values of heavy metals correspond to the Crassostrea shells from Densu Estuary and Anyanui Creek, whereas the highest contents are recorded in the shells from Pra Estuary and Kpone Beach. Densu Estuary and Anyanui Creek are located in areas not affected by major industries, and only Densu is located in a densely urbanized setting. Crassostrea shells from Densu Estuary are only enriched in Ni. However, the Total Organic Carbon content of the sediments of the Densu Estuary indicates anthropogenic organic pollution not evidenced by the composition of Crassostrea shells. The Crassostrea shells from the Pra Estuary show enrichment in most of the analysed trace elements (Li, Be, V, Cu, Cr, Zn, Ga, Y, Sn, Pb, U, Th, ∑REE, and As) compared with other studied sites. This enrichment is related to heavy metals influx to the Pra River by the mining activities, extensive forest clearance, and loss of soil minerals. The Crassostrea shells from Kpone Beach present comparatively high content of some trace elements (Be, Ba, Cu, Zn, Nb, Pb, and REE). The metal pollutants are related to the input of the Heavy Industrial Area of Tema (located around 3.5 km west of Kpone Beach) and urban effluences from the Greater Accra Region. The high content of Ba, Cu, Zn, and Pb in Crassostrea is directly related to high phytoplankton productivity (mainly for diatoms) linked to the input of trace metals transferred into the marine food webs. In addition, some analyses of gastropod shells from Kpone Beach indicate that Cerithium and Nerita are more sensitive to accumulating Ni and As than Crassostrea. The values of trace metals from the Crassostrea shells of the Densu Estuary and Anyanui Creek are comparatively low. Considering the role of Crassostrea shells as bioindicators for heavy metals pollution, the less polluted localities are Anyanui Creek and Densu Estuary, whereas Pra Estuary and Kpone Beach are affected by anthropic activities such as mining, urban effluents, and industry.

From mother to egg: Variability in maternal transfer of trace elements and steroid hormones in common eider (Somateria mollissima)

The Baltic Sea is among the most polluted seas worldwide with elevated concentrations of trace elements (TEs). TEs can induce negative effects on organisms and may be transferred to eggs causing endocrine-disrupting effects on embryos. The Baltic Sea population of common eider (Somateria mollissima) has declined over the last thirty years, but the potential contribution of TEs to this decline is understudied. The aim of this study was to assess maternal transfer of TEs during the incubation period. Associations between TEs and steroid hormone concentrations in eggs (androstenedione, testosterone, pregnenolone and progesterone) were also investigated. Ten nests from Bengtskär (Finland) were monitored, for which hens at the beginning and end of the egg-laying were blood-sampled and their clutches were collected. Red blood cells from females (n = 10) and homogenized eggs (n = 44) were analyzed for 10 TEs (As, Ca, Cd, Cu, Hg, Mg, Ni, Pb, Se and Zn). Maternal and egg concentrations were correlated for Cu, Hg and Se (R2 = 0.51, R2 = 0.51, R2 = 0.52, respectively and all p-values ≤0.01). Three eggs had the highest Pb concentrations (1.43–2.24 μg g−1 ww) ever reported for this species. Although maternal and egg Pb concentrations were not significantly correlated, those eggs were laid by the same female, also having the highest Pb concentration (3.4 μg g−1 ww). Most blood TE concentrations in females were below known toxicity limits, except for Pb where 20 % of 10 females (including one outlier) had concentrations above the toxicity limit reported for subclinical poisoning in Anatini (> 0.2 μg g−1 ww). Steroid hormones in eggs were interrelated, but not correlated to TEs. Overall, the results call for more urgent research into the origin and consequences of high Pb concentrations and continued monitoring of the common eider populations in the Baltic Sea.

Responses to exogenous elicitor treatment in lead-stressed Oryza sativa L.

Heavy metal toxicity adversely affects plants by changing physiological, biochemical, and molecular mechanisms. Lead (Pb) is one of the most common heavy metal pollutants. Hence this study investigated changes caused by exogenous methyl jasmonate (MeJA; 20 and 100 µM) and salicylic acid (SA; 2 and 20 mM) elicitors in local Karacadağ rice exposed to Pb stress (0, 100, and 400 ppm). The effects of elicitors on photosynthetic pigment content (chlorophyll a, chlorophyll b, and total carotenoid), proline, malondialdehyde (MDA), total phenolic and flavonoid, Pb, and total protein contents in stressed plants were evaluated. All parameters studied increased and decreased at varying rates in the treatment groups compared to the Pb-free group (control), indicating that rice plants were affected by Pb stress. The elicitors (MeJA, SA, and MeJA + SA) were applied by foliar spraying. The elicitor treatments increased photosynthetic pigment content, total protein, proline, total flavonoid, and phenolic contents depending on the elicitor type and concentration. MDA and Pb contents, increasing with Pb toxicity, decreased with elicitor treatments, and the stress degree was reduced. When the elicitors were compared, SA was more effective than MeJA in total flavonoid content at 400 ppm Pb toxicity. However, MeJA was more effective in photosynthetic pigment contents, MDA, total protein, Pb, total phenolic, and proline contents. The best results for all parameters examined in rice plants exposed to Pb toxicity were obtained from the 400 ppm Pb + 2 mM SA + 20 µM MeJA treatment group. In conclusion, this study showed that the combined application of MeJA + SA alleviated the harmful effects of Pb by reducing MDA and increasing photosynthetic pigments, total protein, proline, and secondary metabolites, especially at high Pb concentrations. Consequently, this study demonstrated that the combined use of MeJA and SA in rice plants eliminated the negative effects of stress quite effectively, even at high Pb concentrations. Therefore, future studies should focus on the synergistic application of different elicitors to better understand the effects of heavy metal toxicity on plant growth and development.

Investigation of microplastics and potentially toxic elements (PTEs) in sediments of two rivers in Southwestern Nigeria.

Microplastics (MPs) are emerging and ubiquitous contaminants, known to accumulate in river sediments. In many developing nations, the absence of policies for managing plastic waste puts the inland river ecosystems at risk of excessive abundance of plastics and MPs. However, only limited studies have reported MPs in river environments in these countries. The current study therefore examined the abundance and nature of MPs and potentially toxic elements (PTEs) in the sediments of the Odo-Ona and Ogun Rivers in Southwest Nigeria. MPs were extracted from the sediments using the density separation method and categorized according to their size, colour and shapes. The range of MP abundances found in the Ogun River sediments was 66.6 ± 12.2 to 311 ± 20.8 particles/kg, while that of the Odo-Ona River ranged from 133 ± 50 to 433 ± 100 particles/kg. The MPs polymer analyses revealed the presence of polyethylene (PE), polypropylene (PP) and polyamide (PA) particles in the sediments. PE was most abundant in the two rivers, constituting 72.8% and 59.7% of MPs (with 0.5 - 5mm size), recovered from the Odo-Ona and Ogun Rivers, respectively. High concentrations of Cr and Pb with ranges of 10.3 - 48.3 and 10.1 - 211mg/kg, respectively, were detected in the sediments and were associated with anthropogenic effects. This study reveals the impact of indiscriminate waste dumping on the water bodies, and calls for strict enforcement of environmental laws in the country.

Investigating the effect of Pb doping on the structural, electronic, magnetic, and optical properties of wurtzite CdS

This study focuses on comprehensively investigating the crystal structure, electronic, magnetic and optical properties of pure and Pb-doped CdS at different concentrations using first-principles methods with the GGA-PBE+U approximation. Our calculations successfully reproduce the experimentally observed optimized lattice parameters and band gap values for both pure and Pb-doped CdS systems. Band structure results show a large and significant reduction in the band gap of Pb-doped CdS at low concentrations, followed by a steady increase at high Pb concentrations. The electron density distribution show the covalent nature between Cd-S and Pb-S. The optical properties of pur and Pb-doped CdS show: a significant increase in absorption and in reflectivity in the visible and ultraviolet domains with doping. Finally, a reduction in optical transmission in the visible energy domain. These optical analyzes provide essential information on the behavior of these materials, thus broadening its practical applications, notably in the design of optoelectronic devices.

Efficiency of metal(loid) phytostabilization by white lupin (Lupinus albus L.), common vetch (Vicia sativa L.), and buckwheat (Fagopyrum esculentum Moench).

Erosion and leaching of metal(loid)s from contaminated sites can spread pollution to adjacent ecosystems and be a source of toxicity for living organisms. Phytostabilization consists of selecting plant species accumulating little or no metal(loid)s in aerial parts to establish a vegetation cover and thus to stabilize the contaminants in the soil. Seeds of white lupin, common vetch, and buckwheat were sown in greenhouse on soils from former French mines (Pontgibaud and Vaulry) contaminated with metal(loid)s including high concentrations of As and Pb (772 to 1064 and 121 to 12,340mgkg-1, respectively). After 3weeks of exposure, the growth of white lupin was less affected than that of the 2 other species probably because metal(loid) concentrations in roots and aerial parts of lupins were lower (5-20 times less Pb in lupin leaves on Pontgibaud soil and 5-10 times less As in lupin leaves on Vaulry soil than in vetch and buckwheat). To limit oxidation and/or scavenge metal(loid)s, white lupin increased the content of proline and total phenolic compounds (TPC) in leaves and roots by a factor 2 whereas buckwheat stimulated the production of TPC by a factor 1.5-2, and non-protein thiols (NPT) by factors around 1.75 in leaves and 6-12 in roots. Vetch accumulated more proline than white lupin but less NPT than buckwheat and less TPC than the 2 other plant species. The level of oxidation was however higher than in control plants for the 3 species indicating that defense mechanisms were not completely effective. Overall, our results showed that white lupin was the best species for phytostabilization but amendments should be tested to improve its tolerance to metal(loid)s.

Spraying or fertigation? looking for the better method in terms of the lower concentration of Pb and Ni in greenhouse cucumber.

This study was conducted to investigate the status of Lead (Pb) and Nickel (Ni) in greenhouse cucumber affected by fertigation and spraying as a factorial split plot arrangement based on a randomized complete block design (RCBD) with three replications at Soil and Water Research Institute, Karaj, Iran in 2023. The main and sub-plots were respectively fertigation and spraying that was applied in two levels [the minimum permissible concentration of these metals in granular triple super phosphate fertilizer (five ppm Pb and five ppm Ni) as the control treatment, and the maximum permissible concentration of Pb and Ni in granular triple super phosphate fertilizer (50 ppm Pb and 100 ppm Ni)]. Spraying was done in three modes (spraying leaves, leaves + fruit, and fruit). Based on the results, the highest concentration of Pb in the fruit (fruit peel + fruit flesh) (0.295 mg/kg DW) was recorded in the fertigation + spraying with the maximum permissible concentrations of Pb and Ni treatments. A general comparison between the two fertilization methods showed that the sprayingmethod accumulated a higher concentration of Pb in the fruit (i.e., peel + flesh) than the fertigation method. The reverse of this status happened for Ni, so the fertigation method accumulated a higher concentration of Ni in the fruit (skin + flesh) compared to the spraying method. On average, the order of Pb concentration in different organs was as follows: leaf (0.765mg/kg) > fruit peel (0.232mg/kg) > fruit peel + flesh (0.174mg/kg) > fruit flesh (0.129mg/kg). This order for Ni was as follows: fruit flesh (0.597mg/kg) > fruit peel + flesh (0.345mg/kg) > leaf (0.3mg/kg) > fruit peel (0.175mg/kg). These orders show that the status of the heavy metals in plant tissues is related to the nature of the metal, the type of the organ, and the method of fertilization.

Chemical characterization of pellet stove ashes: Elemental fractionation of ashes results in volatile particles with high concentrations of cadmium and lead

Use of wood-based biomass for home heating has increased as a more sustainable and economical alternative to fossil fuel heating sources. However, concerns remain regarding particulate emissions and potential human health effects. Pellet stoves are very efficient combustion sources but still emit high particle numbers of nanoparticles into the environment and generate ash within the stove that could be an exposure source during cleaning. In this study we chemically characterize pellet ash collected from zones (upper and lower) from three stoves and determine the chemical composition of room air during cleaning events. Ash was acid digested using reverse aqua regia and microwave digestion and analyzed by ICP-MS. Indoor air was sampled using impingers before and during stove cleaning to assess ultrafine particulate release and exposure. Within the pellet stove different fractions of ash could be identified by color and macro-scale morphology. Ash fractions collected lower in the stove were predominantly calcium-based, 25 % by weight, and high in refractory trace elements, Fe, Cr, Mn and Ni. In contrast, ash collected higher in the stove was predominantly K and S based (25 and 5 % respectively) and had high concentrations of volatile elements Zn (0.4 %), Cd and Pb. Maximum Cd and Pb ash concentrations were 274 mg/kg and 807 mg/kg respectively corresponding to enrichment factors of 1581 and 870 compared to the respective pellets. Electron microscopy of the particles suggested that ash particles were agglomerates of smaller primary particles and EDS identified areas of high K and S concentration on the particles. Impinger studies of room air during cleaning showed an increase in K, S, Zn, Cd and Pb suggesting a mobilization of upper ash particles into room air upon stove cleaning.

Cognitive- and memory-enhancing activity of Cinnamon (Cinnamomum zeylanicum) aqueous extract in lead acetate-exposed rats

BackgroundLead (Pb) exposure has been linked to reduced academic performance, lower IQ, cognitive and memory impairments, and other psychiatric conditions such as depression and anxiety. Natural antioxidants and dietary sources of phytochemicals, including Cinnamomum zeylanicum (CZ), have been investigated to possibly replace the current adverse reacting drugs used to treat Pb poisoning. Consequently, this study evaluated the activity of CZ against Pb-mediated neurotoxicity. MethodsWistar rats were assigned into six groups (n = 8) namely: Control; Lead acetate (Pb; 100 mg kg−1 body weight [BW]); CZ-pre-treated groups (CZ1 [200 mg.kg−1 BW] + Pb and CZ2 [400 mg kg−1 BW] + Pb); and CZ-only groups (CZ1 and CZ2). After 28 days, neurobehavioral, antioxidant, lipid peroxidation, nitric oxide, and Pb concentration levels, as well as hippocampal and cerebral histology, were evaluated. ResultsFindings showed a significant reduction (p < 0.05) in final body and whole brain weights, cognition, and memory impairments, dysregulation of antioxidant enzymes, lipid peroxidation, and elevated nitric oxide as well as high Pb concentrations in the hippocampus and cerebrum of Pb-exposed rats following comparison to the control and CZ pretreated rats. Histological findings revealed morphological alterations with vacuolated tissue architecture in the hippocampus and cerebrum of Pb-exposed rats while the rats pre-treated with CZ showed similar morphology to the control rats. ConclusionAltogether, the findings showed that CZ was not toxic to the rats but protected against Pb toxicity, mediated possibly through its potent antioxidant, nitric oxide scavenging, and metal chelation activity.

High precision blood lead radiogenic isotope signatures in a community exposed to Pb contaminated soils and implications for the current Pb exposure of the European population

Our study provides the most comprehensive dataset for high-precision radiogenic isotopes of lead (Pb) in blood for the western European population. It investigates their potential for elucidating the contribution of soil Pb to blood Pb using a human biomonitoring survey involving 81 adults and 4 children living in the urban area of Liège (Belgium). Soils in the area show moderate (median of 360 mg/kg) to high (95th percentile of 1000 mg/kg) Pb concentrations, due to former metal processing activities. Blood lead levels (BLL) measured in the study population are, on average, quantitatively consistent with a ∼ 20 % increase due to the exposure to Pb from soils, as estimated by a single-compartment biokinetic model. Consistently, its isotopic composition does not represent an endmember that fully accounts for the variability of Blood lead isotope (BLI) compositions measured in the study population. While some individuals show more thorogenic BLI ratios (relatively more enriched in 208Pb), which could be consistent with a greater exposure to local soils and/or by their country of birth, the BLI data mostly follow a trend roughly parallel to the European Standard Lead Pollution (ESLP) line, within the European leaded gasoline field, even two decades after the withdrawal of this source. Differences in BLI are probably associated with factors related to the presence of Pb in dwellings (pipes, paint) and drinking water distribution system, suggesting that the anthropogenic Pb in use, relevant to human exposure, may contain ore components of different origins, including the Australian Pb ore signature.

Mechanisms of enhancing MgO for stabilization/solidification of Pb-contaminated red clay through CO2 sequestration

Pb-contaminated soil poses significant environmental and health risks as well as soil stability issues. Research on sandy soils highlights CO2-enhanced reactive MgO as a promising solution for improving the solidification of Pb-contaminated soils. However, carbonation effects can differ markedly between soil types owing to varying soil properties. In this study, we evaluated the effects of CO2-enhanced reactive MgO on the engineering and environmental characteristics of Pb-contaminated red clay and explored its mechanism of carbonation solidification. The results showed that CO2-enhanced reactive MgO increased the strength of Pb-contaminated red clay to over 3 MPa within 1 h, which was approximately 25 times the strength of untreated soil (0.2 MPa) and significantly higher than that of reactive MgO-treated, uncarbonated soil (0.8 MPa). The pH of the carbonated soil (9–10) facilitated Pb2+ immobilization, and the increase over the initial parameter elevated the electrical conductivity value. Moreover, CO2-enhanced reactive MgO reduced the Pb2+ leaching concentration to below 0.1 mg/L, even at high Pb concentrations (10,000 mg/kg). Pb2+ transformed into lead carbonates during the carbonation process, with the hydrated magnesium carbonates forming a dense internal structure. This solidification mechanism included chemical precipitation, physical adsorption, and encapsulation. Notably, the carbonation time should be controlled within 1 h to prevent soil expansion. Together, these findings support the potential of CO2-enhanced reactive MgO for efficient and low-carbon application in the solidification of Pb-contaminated red clay.

Trace metals pollution and trophic position of three sea urchin species in the Gulf of California.

Sea urchin species are ecologically important in the Gulf of California and are becoming popular as a local fishery due to their commercial value. The most abundant species are Echinometra vanbrunti, Eucidaris thouarsii, and Tripneustes depressus. The objective of this study was to evaluate cadmium, lead, copper, zinc, and iron concentrations, as well as stable isotope values in these sea urchin species in the Santa Rosalia mining area (STR), in three sites: Punta Gorda, Punta el Aterrizaje, and Punta Salina. The highest Fe concentration (100.2 mg kg-1) was found in E. vanbrunti, while the highest concentrations of Pb (15.1 mg kg-1), Cu (14.5 mg kg-1), and Zn (347.7 mg kg-1) were recorded in E. thouarsii, and the highest Cd concentration (10.8 mg kg-1) was found in T. depressus. The main health risk of trace metal pollution in STR may be caused by Cd and Pb. δ15N and δ13C values were higher in E. thouarsii and T. depressus, respectively; E. thouarsii has the highest trophic position. Specimen size was not related to metal concentrations, but a positive relationship was observed between specimen size and isotopic values in T. depressus. The three species showed different bioaccumulation patterns for the metals analyzed. Additionally, collection sites and seasons play an important role in the variability of metal concentration.

MINERALOGICAL AND GEOCHEMICAL PARAMETERS OF SNOW COVER WITHIN THE ANTHROPOGENICALLY DISTURBED SITES OF THE NADYM-PUR INTERFLUVE (NORTHERN PART OF WESTERN SIBERIA)

The article analyzes the content of metals in solid aerosols and snow water sampled in the anthropogeni-cally disturbed and background sites of the Nadym-Pur interfluve. The results of microscopic studies of solid aerosols showed the presence of secondary minerals, technogenic formations, as well as a large amount of pyrite in samples from the eastern part of the study area. The maximum concentrations of metals in solid aero-sols were found in snow of the sanitary protection zones of waste disposal facilities, with the exception of Ca, which prevails in snow cover of Novy Urengoy (up to 10% of dry matter). The urbanized area is characterized by the highest values of dust load (up to 111 mg/m2 a day). The local contamination with Ba within the waste landfills in Novy Urengoy is associated with the sites of barite and drilling waste processing. We applied the factor analysis to identify the main metal associations characteristic of solid aerosols from different functional zones: Ca-Co-V-Mn (city), Ba-Sr-K-Na and Cd-Cu-Pb (waste disposal sites), Cu-Ni-Cd (the entire studied area). Based on the study of the content of dissolved forms in snow water, a high mobility of metals in the northern landscapes and its decrease in urban environment were revealed. The mineralogical and geochemical analysis of snow suggests the influence of the Norilsk industrial region on the eastern part of the Nadym-Pur interfluve, Zn, Cu, Ni, Pb and the mineral pyrite being the indicators. The risks of environmental pollution under the aerotechnogenic transport are associated with high content of Zn, Cu, Ni, Pb and Ba in solid aero-sols. The calculation of the Toxicity Probability Index (MERMQ) showed that some aerosol samples from the landfill sites have a high probability of biological effects. Using data on the chemical composition of soils and soil water, no visible effect of snow pollution on the growth of metal concentrations in soil and soil water was revealed, with the exception of local contamination with Ba, which led to a twofold increase in the content of the metal in the upper soil horizon.

The Efficiency of the Eucalyptus sp. Plant in Absorbing Pollutants Results from Vehicle Exhausts in the Baghdad City

Air pollution is one of the serious problems facing the world today because of constant changes in environmental concentration levels of some gases and heavy metals due to humans. Especially when contaminants on the soil and leaves are deposited and transferred to the remainder of the plant. The present study was carried out to assess the theory concentrations of air pollutants in some areas of the city of Baghdad and their effects on the plant (Eucalyptus sp.) by calculating the heavy metal, exposed to roadside vehicles pollution in the city of Baghdad. The gaseous air pollutants levels were measured in five sites namely Al-Doura, Al-Kadhimiya, Palestine Street, and Al-Shaab to represent the urban areas and Al-Rashidiya site to represent the rural area. Included carbon dioxide CO2, sulfur dioxide SO2, and nitrogen dioxide NO2. Also, heavy metal concentrations were measured cadmium Cd and lead Pb. Concentrations of air pollutants, for all studied sites, ranged between 281.33-702.33 ppm, 0.15-3.50 ppm, 0.004-0.532 ppm, 0.132-1.16 μg m-3, 1.75-5.75 μg m-3, for CO2, NO2, SO2, Cd, and Pb, respectively. High concentrations of Cd and Pb were recorded in Eucalyptus sp. (1.51 mg/kg and 5.31 mg kg-1, respectively).

Quantitative Insights into Phosphate-Enhanced Lead Immobilization on Goethite.

Despite extensive study, geochemical modeling often fails to accurately predict lead (Pb) immobilization in environmental samples. This study employs the Charge Distribution MUlti-SIte Complexation (CD-MUSIC) model, X-ray absorption fine structure (XAFS), and density functional theory (DFT) to investigate mechanisms of phosphate (PO4) induced Pb immobilization on metal (hydr)oxides. The results reveal that PO4 mainly enhances bidentate-adsorbed Pb on goethite via electrostatic synergy at low PO4 concentrations. At relatively low pH (below 5.5) and elevated PO4 concentrations, the formation of the monodentate-O-sharing Pb-PO4 ternary structure on goethite becomes important. Precipitation of hydropyromorphite (Pb5(PO4)3OH) occurs at high pH and high concentrations of Pb and PO4, with an optimized log Ksp value of -82.02. The adjustment of log Ksp compared to that in the bulk solution allows for quantification of the overall Pb-PO4 precipitation enhanced by goethite. The CD-MUSIC model parameters for both the bidentate Pb complex and the monodentate-O-sharing Pb-PO4 ternary complex were optimized. The modeling results and parameters are further validated and specified with XAFS analysis and DFT calculations. This study provides quantitative molecular-level insights into the contributions of electrostatic enhancement, ternary complexation, and precipitation to phosphate-induced Pb immobilization on oxides, which will be helpful in resolving controversies regarding Pb distribution in environmental samples.

Application of some calibration strategies in comparison to determine Cr, Ni, Cu, Zn, As, and Pb in contaminated plants by wavelength dispersive x‐ray fluorescence

AbstractThe study of nonstandard samples wherein their element compositions differ from those of routine samples motivates analysts to look for new methodological approaches. To determine the high concentrations of Cr, Ni, Cu, Zn, As, and Pb in polluted plants, the authors applied wavelength dispersive x‐ray fluorescence (WDXRF), using three calibration strategies in comparison. The following sets of calibration samples were tested: available plant and biological CRMs; synthetic samples; and “house reference materials” (HRMs). The synthetic samples were prepared, adding small portions of the loose sediment CRMs to a plant CRM. The polluted plant samples, analyzed by atomic absorption spectrometry and inductively coupled plasma mass spectrometry, were used as HRMs to construct the calibration curves and validate XRF results. It was ascertained that all three calibration strategies can be used to quantify above elements in contaminated plants, providing different precision of WDXRF results. The calibration procedure with HRMs has provided the least errors in the element determinations. Calibration with synthetic samples causes larger errors due to some differences in chemical compositions between calibration and analyzed samples as well as due to probable errors in the synthetic sample preparation. The calibration with plant and biological samples is of limited applicability in XRF of contaminated plants by reason of narrow content ranges of some elements.