Influence of traffic activity on heavy metal concentrations of roadside farmland soil in mountainous areas

Understanding heavy metal toxicity: Implications on human health, marine ecosystems and bioremediation strategies

Heavy metals are constituents of the natural environment and are of great importance to both natural and artificial processes. But in recent times the indiscriminate use of heavy metals especially for human purposes has caused an imbalance in natural geochemical cycles. This imbalance has caused contamination of heavy metals into natural resources and such as soil and a marine ecosystem. Long exposure and higher accumulation of given heavy metals are known to impose detrimental and even lethal effects on humans. Conventional remediation techniques of heavy metals provide good results but have negative side effects on surrounding environment. The role played by microbes in bioremediation of heavy metals is well reported in the literature and understanding the role of molecules in the process of metal accumulation its reduction and transformation into less hazardous state, has myriads of biotechnological implications for bioremediation of metal-contaminated sites. The current review presents the implications of heavy metals on human health and marine ecosystems, conventional methods of heavy metal removal and their side effects on the environment. Bioremediation approaches have been discussed as well in this review, proving to be a more sustainable and eco-friendly approach towards remediation of heavy metals.

Physiological, cytological and multi-omics analysis revealed the molecular response of Fritillaria cirrhosa to Cd toxicity in Qinghai-Tibet Plateau

Fritillaria cirrhosa, an endangered plant endemic to plateau regions, faces escalating cadmium (Cd) stress due to pollution in the Qinghai-Tibet Plateau. This study employed physiological, cytological, and multi-omics techniques to investigate the toxic effects of Cd stress and detoxification mechanisms of F. cirrhosa. The results demonstrated that Cd caused severe damage to cell membranes and organelles, leading to significant oxidative damage and reducing photosynthesis, alkaloid and nucleoside contents, and biomass. Cd application increased cell wall thickness by 167.89% in leaves and 445.78% in bulbs, leading to weight percentage of Cd increases of 76.00% and 257.14%, respectively. PER, CESA, PME, and SUS, genes responsible for cell wall thickening, were significantly upregulated. Additionally, the levels of metabolites participating in the scavenging of reactive oxygen species, including oxidized glutathione, D-proline, L-citrulline, and putrescine, were significantly increased under Cd stress. Combined multi-omics analyses revealed that glutathione metabolism and cell wall biosynthesis pathways jointly constituted the detoxification mechanism of F. cirrhosa in response to Cd stress. This study provides a theoretical basis for further screening of new cultivars for Cd tolerance and developing appropriate cultivation strategies to alleviate Cd toxicity.

Assessment and machine learning prediction of heavy metals fate in mining farmland assisted by Positive Matrix Factorization

The accurate pollutant prediction by Machine Learning (ML) is significant to efficient environmental monitoring and risk assessment. However, application of ML in soil is under studied. In this study, a Positive Matrix Factorization (PMF) assisted prediction method was developed with Support Vector Machine (SVM) and Random Forest (RF) for heavy metals (HMs) prediction in mining farmland. Principal Component Analysis (PCA) and Redundancy Analysis (RDA) were selected to pretreat data. Experiment results illustrated Cd was the main pollutant with heavy risks in the study area and Pb was easy to migrate. The method effects of HMs total concentration predicting were PMF > Simple > PCA > PCA - PMF, and RF predicted better than SVM. Data pretreatment by RDA prior inspection improved the model results. Characteristic HMs Tessier fractions prediction received good effects with average R value as 0.86. Risk classification prediction performed good in Cd, Cu, Ni and Zn, however, Pb showed weak effect by simple model. The best classifier method for Pb was PMF - RF method with relatively good effect (Area under ROC Curve = 0.896). Overall, our study suggested the combination between PMF and ML can assist the prediction of HMs in soil. Spatial weighted attribute of HMs can be provided by PMF.

Determination of the Concentration of Heavy Metals in Artisanal Cheeses Produced in the Mexican States of Tabasco and Chiapas

Cheese consumption provides humans with minerals, proteins, carbohydrates, and vitamins. In Mexico, several cheese varieties are produced, each with its texture, scent, and flavor. The artisanal cheeses made in the states of Tabasco and Chiapas-including, among others, the varieties named crema (cream), doble crema (double cream), oaxaca, panela, fresco, bola, poro, cotija, and asadero-have a high demand in the domestic and foreign markets. The intensification of anthropic activity in these states causes an increased emission to the environment of contaminants like heavy metals, which could reach human foodstuffs through the food chains. In particular, heavy metal contents in cheeses consumed daily by these states' local populations might represent a public health risk. Because of that, our objectives in this work were to determine the concentrations of lead, cadmium, nickel, copper, zinc, and iron in artisanal cheeses produced in the states of Tabasco and Chiapas and to determine the values of the hazard quotient (HQ), total hazard quotient (THQ), and cancer risk total (CRT) for adult and young men and women. The results of our analyses of cheese samples from the states of Tabasco and Chiapas showed that the average concentrations (mg kg-1) of cadmium (0.0023 ± 0.002, 0.0023 ± 0.002 mg kg-1, respectively, for each state), lead (0.0047 ± 0.00, 0.0051 ± 0.002), nickel (0.0039 ± 0.0046, 0.0031 ± 0.0039), copper (0.0199 ± 0.021, 0.0202 ± 0.022), zinc (0.1611 ± 0.18, 0.194 ± 0.21), and iron (61.84 ± 4.23, 65.76 ± 6.61 mg kg-1), the first three values lower than the limits established by the FAO/WHO and Codex Alimentarius. The value of THQ that we obtained was less than one, and that of CRT was within the limits established by the US-EPA, which means that the consumption of artisanal cheeses from Tabasco and Chiapas by humans does not imply a risk of disease or cancer.

Characterization of heavy metal content distribution and evaluation of soil pollution in Maqin County, Qinghai Province, China

The Qinghai-Tibet Plateau stands as the loftiest geographical area on our planet, frequently denoted as the "Crown of the Globe." To acquire an exhaustive comprehension of the heavy metal contamination situation in the topsoil of Maqin County, Qinghai Province, a total of 1616 surface soil specimens were gathered across a 6300 km2 area. An examination was carried out on 12 metallic elements to investigate the impact of diverse geological contexts, soil categorizations, and land utilization practices on the levels of heavy metals. Additionally, the fundamental factors contributing to these trends were probed. The findings unveiled that the mean levels of the 12 metallic elements in the topsoil of Maqin County surpassed or equaled the baseline values of soil heavy metal concentrations within the research region. The coefficients of variation (CV) values for Hg, Sb, Ni, and Pb exceeded 30%, with Hg showing strong variation. The overall pollution level in the study area was classified as mild, posing a moderate ecological risk. In this study, we performed a multi-factor analysis of the significant differences in heavy metal concentrations among different geological backgrounds, soil types, and land-use types. The results showed that geological background had extremely significant impacts on elements such as Ba, Be, Cd, Cr, Cu, Hg, Ni, Sb, Tl, and Zn (p < 0.01). Soil type had an extremely significant influence on Be, Cd, Cu, and Zn (p < 0.01), as well as a significant influence on Ba (p < 0.05). Land-use type had an extremely significant impact on Ba (p < 0.01) and a significant impact on Cd (p < 0.05). Building upon the amalgamation of the outcomes from the Pearson correlation analysis, it was inferred that the main source of heavy metals in Maqin County, Qinghai Province, was the geological background.

Past, present and future trends in the remediation of heavy-metal contaminated soil - Remediation techniques applied in real soil-contamination events

Most worldwide policy frameworks, including the United Nations Sustainable Development Goals, highlight soil as a key non-renewable natural resource which should be rigorously preserved to achieve long-term global sustainability. Although some soil is naturally enriched with heavy metals (HMs), a series of anthropogenic activities are known to contribute to their redistribution, which may entail potentially harmful environmental and/or human health effects if certain concentrations are exceeded. If this occurs, the implementation of rehabilitation strategies is highly recommended. Although there are many publications dealing with the elimination of HMs using different methodologies, most of those works have been done in laboratories and there are not many comprehensive reviews about the results obtained under field conditions. Throughout this review, we examine the different methodologies that have been used in real scenarios and, based on representative case studies, we present the evolution and outcomes of the remediation strategies applied in real soil-contamination events where legacies of past metal mining activities or mine spills have posed a serious threat for soil conservation. So far, the best efficiencies at field-scale have been reported when using combined strategies such as physical containment and assisted-phytoremediation. We have also introduced the emerging problem of the heavy metal contamination of agricultural soils and the different strategies implemented to tackle this problem. Although remediation techniques used in real scenarios have not changed much in the last decades, there are also encouraging facts for the advances in this field. Thus, a growing number of mining companies publicise in their webpages their soil remediation strategies and efforts; moreover, the number of scientific publications about innovative highly-efficient and environmental-friendly methods is also increasing. In any case, better cooperation between scientists and other soil-related stakeholders is still required to improve remediation performance.

Phytoremediation as a potential technique for vehicle hazardous pollutants around highways

With the synchronous development of highway construction and the urban economy, automobiles have entered thousands of households as essential means of transportation. This paper reviews the latest research progress in using phytoremediation technology to remediate the environmental pollution caused by automobile exhaust in recent years, including the prospects for stereoscopic forestry. Currently, most automobiles on the global market are internal combustion vehicles using fossil energy sources as the primary fuel, such as gasoline, diesel, and liquid or compressed natural gas. The composition of vehicle exhaust is relatively complex. When it enters the atmosphere, it is prone to a series of chemical reactions to generate various secondary pollutants, which are very harmful to human beings, plants, animals, and the eco-environment. Despite improving the automobile fuel quality and installing exhaust gas purification devices, helping to reduce air pollution, the treatment costs of these approaches are expensive and cannot achieve zero emissions of automobile exhaust pollutants. The purification of vehicle exhaust by plants is a crucial way to remediate the environmental pollution caused by automobile exhaust and improve the environment along the highway by utilizing the ecosystem's self-regulating ability. Therefore, it has become a global trend to use phytoremediation technology to restore the automobile exhaust pollution. Now, there is no scientific report or systematic review about how plants absorb vehicle pollutants. The screening and configuration of suitable plant species is the most crucial aspect of successful phytoremediation. The mechanisms of plant adsorption, metabolism, and detoxification are reviewed in this paper to address the problem of automobile exhaust pollution.

Pond Sediments Reveal the Increasing Importance of Road Runoff as a Source of Metal Contamination in Industrialized Urban Environments Downwind of Pittsburgh, Pennsylvania (USA)

Toxic levels of trace metals from human activities accumulate in natural environments, yet these metal mixtures are rarely characterized or quantified. Metal mixtures accumulate in historically industrial urban areas and change as economies shift. Previous research has often focused on the sources and fate of a specific element, which limits our understanding of metal contaminant interactions in our environment. Here, we reconstruct the history of metal contamination in a small pond downstream of an interstate highway and downwind of fossil fuel and metallurgical industries that have been active since the middle of the nineteenth century. Metal contamination histories were reconstructed from the sediment record using metal ratio mixing analysis to attribute the relative contributions of contamination sources. Cadmium, copper, and zinc concentrations in sediments accumulated since the construction of major road arteries in the 1930s and 40s are, respectively, 3.9, 2.4, and 6.6 times more concentrated than those during industry-dominated time periods. Shifts in elemental ratios suggest these changes in metal concentrations coincide with increased contributions from road and parking lot traffic, and to a lesser extent, from airborne sources. The metal mixture analysis demonstrates that in near-road environments, contributions from modern surface water pathways can obscure historical atmospheric industrial inputs.

Vehicular emission and its impact on heavy metal accumulation and photosynthetic pigments on pine needles in Pahalgam forest ecosystem

Human interference is rising day by day which adds more problems to conserve valuable forest resources. Vehicular exhausts are the main source of heavy metals that have detrimental impacts on the vegetation. The research provides comprehension about the increase in vehicular traffic along the Pahalgam highway, which is disturbing the balance of the forest ecosystem. The concentration of heavy metals and leaf pigments were determined in the leaf tissues collected along with the roadside pine trees in the Pahalgam resort. A total of 25 samples at each sampling site were collected in 100 m diameter along main road. High vehicular movements in summer correlated with the high accumulation of heavy metals such as Pb²⁺ (0.563 mg/kg), Ni²⁺ (0.271 mg/kg), and Cu²⁺ (0.202 mg/kg) in pine needles. However, Zn²⁺ exhibited higher concentration (0.468 mg/kg) at Batakote and Cd²⁺ (0.05 mg/kg) at Pahalgam in autumn. Moreover, total chlorophyll content determined low (1.97 mg/g) at Pahalgam in autumn and high (3.81 mg/g) at Chandanwari in summer. In general, the chlorophyll content in the pine needles was certainly affected by the accumulation of heavy metals which indicating a negative correlation of chlorophyll content with heavy metals. Thus, the increase in traffic movement and tourist influx significantly affects the accumulation of heavy metals and decreases the pigment content in the pine needles. Rapid tourist influx in world-famous health resorts is dramatically influencing the forest ecosystem. Therefore, the need is to use green fuel or ban the old vehicles which can be helpful in maintaining the balance of the forest ecosystem.

Status, Sources and Assessment of Potentially Toxic Element (PTE) Contamination in Roadside Orchard Soils of Gaziantep (Türkiye)

To identify the sources of contamination with potentially toxic elements (PTEs) in roadside orchard soils and to evaluate the potential ecological and environmental impacts in Gaziantep, soil samples from 20 mixed pistachio and olive orchards on roadsides with different traffic densities and at different distances to the roads were analyzed. Concentrations were 23,407.36 ± 4183.76 mg·kg^-1 for Fe, 421.78 ± 100.26 mg·kg^-1 for Mn, 100.20 ± 41.92 mg·kg^-1 for Ni, 73.30 ± 25.58 mg·kg^-1 for Cr, 65.03 ± 12.19 mg·kg^-1 for Zn, 60.38± 7.91 mg·kg^-1 for Pb, 17.74 ± 3.35 mg·kg^-1 for Cu, 14.93 ± 4.94 mg·kg^-1 for Co, and 0.30 ± 0.12 mg·kg^-1 for Cd. It was found that the Ni content in 51% and the Cr content in 18% of orchard soils were above the legal limits for agricultural soils (pH > 6) in Türkiye. Factor analysis (FA) showed that Co, Cr, Cu, Fe, Mn, Ni, and Pb loaded on the first factor (FC1), while Cd and Zn loaded mostly on the second factor (FC2). It was found that Cr, Ni, and Pb were primarily enriched through pedogenic processes, whereas Cd most likely originated from agricultural activities, while the impact of road traffic as source of PTE contamination was insignificant. It has been revealed that the soils are of low quality for agricultural production due to PTE contamination (PIave ≥ 1). The SOPI values from environmental and ecological individual indices showed that the soil pollution level was moderate for Cd, Ni, and Pb, and low for Cr. The soil pollution index (SOPI) proved to be suitable for evaluating and comparing PTE pollution in regions with different soil properties.

Source appointment of potentially toxic elements (PTEs) at an abandoned realgar mine: Combination of multivariate statistical analysis and three common receptor models

Identifying pollution sources and quantifying their contributions are of great importance for proposing management and control strategies of potentially toxic elements (PTEs) in soil. In this study, multivariate statistical analysis and receptor models were combined to identify potential pollution sources and apportion their contributions at an abandoned realgar mine. Principal component analysis (PCA) result shows that three factors are responsible for PTEs, which is also supported by cluster analysis (CA). Correlation analysis and spatial analysis also show that the heavy metals from the same pollution source are of higher correlation coefficients and similar spatial distribution. Three receptor models were combined to apportion contributions of pollution sources. Three pollution sources were detected by absolute principal component analysis-multiple linear regression (APCA-MLR). In contrast, four sources were identified by positive matrix factorization (PMF) and UNMIX. Soil parent material was heavily loaded on Cr, Cu, Ni and Zn, occupying the largest average contribution (30%-43%). Cadmium was mainly derived from agricultural activities with contribution higher than 60%. Arsenic accumulation was mainly associated with mining and smelting activity with contribution higher than 80%. PMF and UNMIX models showed that more than half of Pb concentrations were influenced by industrial activities. Comparatively speaking, APCA-MLR was a well-performing model for all PTEs even though it only detected three pollution sources. The study showed that it was a good choice to apply multiple receptor models in order to achieve more reliable and objective conclusions of source appointment.

Machine learning can identify the sources of heavy metals in agricultural soil: A case study in northern Guangdong Province, China

Source tracing of heavy metals in agricultural soils is of critical importance for effective pollution control and targeting policies. It is a great challenge to identify and apportion the complex sources of soil heavy metal pollution. In this study, a traditional analysis method, positive matrix fraction (PMF), and three machine learning methodologies, including self-organizing map (SOM), conditional inference tree (CIT) and random forest (RF), were used to identify and apportion the sources of heavy metals in agricultural soils from Lianzhou, Guangdong Province, China. Based on PMF, the contribution of the total loadings of heavy metals in soil were 19.3% for atmospheric deposition, 65.5% for anthropogenic and geogenic sources, and 15.2% for soil parent materials. Based on SOM model, As, Cd, Hg, Pb and Zn were attributed to mining and geogenic sources; Cr, Cu and Ni were derived from geogenic sources. Based on CIT results, the influence of altitude on soil Cr, Cu, Hg, Ni and Zn, as well as soil pH on Cd indicated their primary origin from natural processes. Whereas As and Pb were related to agricultural practices and traffic emissions, respectively. RF model further quantified the importance of variables and identified potential control factors (altitude, soil pH, soil organic carbon) in heavy metal accumulation in soil. This study provides an integrated approach for heavy metals source apportionment with a clear potential for future application in other similar regions, as well as to provide the theoretical basis for undertaking management and assessment of soil heavy metal pollution.

Coexistence of Cr and Ni in anthropogenic soils and their chemistry: implication to proper management and remediation

In anthropogenic soils, there have been relatively limited studies focusing on Cr and Ni contaminants because they exhibit less toxic effects to overall ecosystem and human health than other metal contaminants. In recent years, however, soil contamination with Cr and Ni has become a serious concern in several parts of the world because of the continuously increasing concentrations of these metals due to accelerated industrialization and urbanization. To investigate the status of soil contamination with Cr and Ni by anthropogenic activities, relevant global data sets in different land-use types reported by several studies were reviewed. This review presents the significant work done on Cr and Ni concentrations in roadside, central business district (CBD), and industrial soils in 46 global cities and evaluated their correlation by global data in the past few years. The highest concentrations of Cr and Ni were observed in industrial soils. Furthermore, a significant relationship was found between Cr and Ni concentrations in the soils, which might be because both metals are released from the same sources or anthropogenic activity processes. We also discuss the state of knowledge about the chemistry and distribution of Cr and Ni in the soil environment to understand how their processes such as redox reaction, precipitation-dissolution, and sorption-desorption affect the remediation of Cr- and Ni-contaminated soils using in situ immobilization technology. Application of organic and inorganic immobilizing agents (e.g., lime, compost, and sulfur) for the clean-up of Cr- and Ni-contaminated soils has received increasing interest from several researchers worldwide. Several immobilizing agents have been suggested and experimentally tested with varying degrees of achievement in Cr- and Ni-contaminated soils. Overall, the use of sulfur-containing amendments and pH-increasing materials could be considered the best options for the remediation of co-contamination of Cr and Ni in soil.

10 years long-term assessment on characterizing spatiotemporal trend and source apportionment of metal(loid)s in terrestrial soils along the west coast of South Korea

Long-term trends in the spatial distributions and sources of metal(loid)s in soils adjacent to the west coastal areas of South Korea have been systematically investigated for 10 years (2010-2019). Monitoring in 17 sites clearly showed site- and region-specific distributions, being associated with land use type (significant differences, as road > agriculture > wild) (P < 0.05), rather than temporal variation. The great concentrations of all metal(loid)s were found near Lake Shihwa (LS) and Geum River (GG), near the road, indicating that transportation activity was the main source of metal(loid)s contamination in soil. Especially, Cd (0.5 mg kg^-1), Hg (0.04 mg kg^-1), Pb (65 mg kg^-1), and Zn (184 mg kg^-1), related to the transportation activity near the road, showed twice greater than other land use types, on average. The concentration of metal(loid)s in each site and with the same land use type did not greatly vary over the years, with no significant annual difference (P > 0.05). The degree of metal(loid)s contamination compared to the background levels was identified in the order of Pb > Zn > Cr > Cu > As>Cd > Ni > Hg, with the contaminated hotspots mostly in LS or GG. The potential ecological risk was evidenced for Cd and Hg, but such a trend was temporally irregular over the years, indicating site-specificity. The sources of metal(loid)s were carefully determined as natural (20%), fuel combustion & agricultural pollution (43%), and vehicular emissions (37%) using the Positive Matrix Factorization model. The relative contribution of each source to contamination over the last decade was found to be similar, supporting that site-dependent lesser variation in metal(loid)s contamination in the coastal areas of South Korea. Overall, the distribution of metal(loid)s in the soil near the west coastal areas over the last decade largely depended on land use activities, and contamination degree was associated with non-point sources, such as transportation and fuel combustion.

Health risk estimations and geospatial mapping of trace metals in soil samples around automobile mechanic workshops in Benin city, Nigeria

This study was carried out to assess the distribution of trace metals in soil samples from selected automobile mechanic workshops (AMWs) in Benin City, spatially map the concentrations and estimate the health risk indices for the exposed populace. Topsoil samples were collected from twenty-one (21) AMWs in Benin City in 3 composites for three months at each station. Soil samples were analyzed for heavy metals (Pb, Cd, Fe, Cu, Ni, Cr, and Zn) using Atomic Absorption Spectrophotometer. The non-carcinogenic risks caused by exposure to the metals were insignificant, characterized by in mean values of hazard quotient (HQ) and hazard index (HI) below one (1) in adults and children. Carcinogenic risk (CR) occurred only in the children exposed to nickel through ingestion; attributable to ingestion. In adults and children, the risks associated with the uptake routes were in the order of ingestion > dermal contact > inhalation. The hazard index (HI) values of heavy metals for children and adults decreased in the order of Pb > Cr > Cd > Cu > Zn > Ni and were all lower than one (1), which indicated that the children and adults were not at non-carcinogenic risk. The contamination factors (CF) of all metals analyzed were lower than one (1), suggesting low contamination. The average CF decreased in the order of Pb (0.3715) > Zn (0.14) > Cu (0.087) > Cr (0.013) > Ni (0.01) > Fe (0.0007). Potential ecological risks of the trace metals in soils of these workshops revealed low pollution of the soils by the metals. Results indicated that the three routes of uptake in adults and children decreased in the order of ingestion > dermal > inhalation. The non-carcinogenic risks posed by metals to the children and adults were insignificant. Ingested nickel however posed potential carcinogenic risk to only the children. The toxicodynamics of heavy metals in the soil profile demonstrated in this study could be a vital information for future studies and decisions on the management of the health and environment of the study area.

Understanding heavy metal accumulation in roadside soils along major roads in the Tibet Plateau

The heavy metal accumulation in the Tibet Plateau (TP) poses a serious ecologic risk to the health of human and the other biota. Given the TP far away from the large anthropogenic emission sources, the rapid development of traffic activities during last several decades possibly leads to the elevated heavy metal concentration in the roadside soils. Therefore, we comprehensively assessed the heavy metal distribution in the 0-5 cm and 15-20 cm depth soils located at 5 m, 50 m, and 100 m distance to the edge of two major roads among the different vegetation covers and climatic conditions in the TP to verify this hypothesis. Results show that most of heavy metal concentrations in soils of different distance to the major road display an insignificant difference. The Nemero Synthesis indexes which represent the risk of pollution for these regions almost range 1 to 2 (low pollution risk), except 12.7 (extreme pollution risk) at one site. These indicate the limited impacts from the traffic activities for the whole region, but at some specific sites with the elevated traffic pollution. The forest cover at the altitude of 3700-4100 m has the highest mercury accumulation due to the vegetation and climatic factors induced the higher atmospheric depositions and stronger complexation with the organic matters. The statistical analysis finally suggests the geogenic weathering processes, climate, terrain and vegetation play an important role in shaping heavy metal distribution along the roadside of the TP.

Appraisal of contamination of heavy metals and health risk in agricultural soil of Jhansi city, India

The accumulation of heavy metals (HMs) in soil is presently a significant threat to the environment. The Cu, Mn, Zn, Cd, Pb, Ni, and Co concentrations were assessed in the agricultural soil samples. The results of various contamination indices including contamination factor, geo-accumulation indices, and ecological risk indices revealed that Cd is responsible for moderate to high contamination of soil. The multivariate statistical analyses including PCA, HCA, and correlation matrix suggested the mixed origin of HMs in the soil. Ingestion was found to be a primary route of exposure while dermal and inhalation exposure was negligible. Overall, the non-carcinogenic health risks were well within the safe limit to human health. However, healthwise, children were likely to be at greater risk compared with adults, due to their generally increased exposure to toxic agents through hand/mouth ingestion. Moreover, no carcinogenic risks were determined through the inhalation exposure of Cd, Ni, and Co.

Effects of soil lead exposure and land use characteristics on neurodevelopment among children under 3 years of age in northern Taiwan

Lead (Pb) exposure increases the risks of neurodevelopmental disorders in children. Child-specific activities and land use scenarios may lead to elevated opportunities for Pb exposure through the soil. Therefore, we investigated hair and fingernail Pb concentrations among young children in northern Taiwan, in relation to soil Pb pollution and land use characteristics. We also explored the effect of the Pb exposure burden and land use scenarios on neurobehavioral development. In total, 139 healthy children under 3 years of age were recruited in October 2011 to April 2014. Pb levels in hair and fingernail samples were determined using an inductively coupled plasma/mass spectrometer. Pb concentrations in soils and land use types surrounding the children's homes were accessed by a geographic information system to identify any associations with hair Pb levels. The Bayley Scales of Infant and Toddler Development (Bayley-III) were used to evaluate the cognitive, language, and motor development of the children. A multivariable regression model was performed to assess the effects of soil Pb levels and land-use status on Pb exposure in children, as well as associations of Pb exposure and land-use scenarios with neurodevelopmental abilities. Geometric mean Pb concentrations in hair, fingernails, and soil were 2.9 ± 4.8 μg/g, 0.8 ± 5.1 μg/g, and 20.8 ± 4.3 mg/kg, respectively. The multivariable analysis indicated that soil Pb concentrations and green areas around residences had potential links with Pb exposure among children in northern Taiwan. Hair Pb concentrations were negatively associated with expressive language scores. Soil Pb exposure was positively associated with hair Pb concentrations. Land use types around the children's homes in northern Taiwan were associated with their neurodevelopment. Increased green areas were negatively associated with hair Pb concentrations. Living near a highway may have had negative impacts on gross motor scores. A healthy residence can avoid potential health risks for children during their early life.

Heavy metal phytoremediation potential of the roadside forage Chloris barbata Sw. (swollen windmill grass) and the risk assessment of the forage-cattle-human food system

This study presents the assessment of the risks incidental to the growth of the common tropical grass species Chloris barbata Sw. (swollen windmill grass) on road margins contaminated with Pb and Cd. Pot experiments were first carried out to quantify the Pb and Cd accumulation potential of the plant species in various plant parts as a function of the metal concentration in soil. C. barbata was found to be a hyperaccumulator for Cd (BCF>1, for aerial parts) and an excluder of Pb (BCF<1, for aerial parts). As the plant was found to accumulate Pb in its roots with TF<1, it can be considered a phytostabilizer of Pb. The mathematical relationship developed between soil concentrations of Pb and Cd and their corresponding concentrations in aerial parts were used in combination with the concentrations of these heavy metals reported in roadside soils to obtain estimates of their accumulation in the forage and consequently in the animal organs. Risk to the consumers of offal was estimated. It was found that the consumption of kidney meat was riskier than the consumption of liver meat. Furthermore, it was seen that despite the nearly two order less concentrations of Cd in roadside soils compared to Pb, it was posing a higher risk. For the median concentrations of Pb reported in roadside soils and cattle feeding exclusively on C. barbata growing on roadside soils, the HQ exceeded 1 for weekly consumption of kidney meat above 650 g. For median Cd concentrations, consumption of kidney meat above 230 g/week resulted in HQ>1. The scenario considered for risk assessment is significant for India, where stray grazing of cattle on road margins is common and offal offers a cheap source of animal protein for the economically poor.

Occurrence of Chemical Contaminants in Peruvian Produce: A Food-Safety Perspective

The presence of chemical contaminants in agricultural products is a continued food-safety challenge in Peru. This country has robust agriculture potential, but its output of fruits and vegetables is severely impacted by massive mining activities, as well as poor farming practices, including the use of polluted irrigation water, misuse of pesticides, and inadequate postharvest conditions. This review examines the current scientific knowledge on the levels of pesticide residues, heavy metals, and mycotoxins on crops produced in Peru. The available data shows that several crop varieties are contaminated with these classes of chemical contaminants, and at levels that exceed the national and international permissible limits. The abundance of chemical contaminants in produce indicates a relevant food-safety issue, which increases the risks of chronic human diseases, like cancer—a leading cause of death in Peru. Finally, this review presents recommendations to address these contamination problems in produce grown in the Andean country.

The adaptive landscape of a metallo-enzyme is shaped by environment-dependent epistasis

Enzymes can evolve new catalytic activity when environmental changes present them with novel substrates. Despite this seemingly straightforward relationship, factors other than the direct catalytic target can also impact adaptation. Here, we characterize the catalytic activity of a recently evolved bacterial methyl-parathion hydrolase for all possible combinations of the five functionally relevant mutations under eight different laboratory conditions (in which an alternative divalent metal is supplemented). The resultant adaptive landscapes across this historical evolutionary transition vary in terms of both the number of “fitness peaks” as well as the genotype(s) at which they are found as a result of genotype-by-environment interactions and environment-dependent epistasis. This suggests that adaptive landscapes may be fluid and molecular adaptation is highly contingent not only on obvious factors (such as catalytic targets), but also on less obvious secondary environmental factors that can direct it towards distinct outcomes.

The metaphor of an adaptive landscape is presented quantitatively by looking at molecular adaptations and their catalytic consequences in a recently evolved bacterial enzyme. The study identifies both genotype-by-environment interactions and environment-dependent epistasis as factors that can alter the fitness of functional mutations.

Monitoring of copper accumulation in water, soil, forage, and cows impacted by heavy automobiles in Sargodha, Pakistan

The instant endeavor was undertaken to monitor copper (Cu) contents in water, soil, forage, and cow's blood impacted by heavy automobiles in Sahiwal town of district Sargodha, Pakistan. The samples were collected in triplicates with a total of 120 soil and water samples with corresponding forage samples. For the analysis of metal concentration in cows, 60 blood samples were collected from the cows feeding on these forages on selected sites. Metal contents were analyzed by atomic absorption spectrophotometry. The results showed that water samples contained mean values of Cu concentration ranged from 1.01 to 0.444 mg/kg at all sites. It was maximum at site 3 and minimum at site 6. The soil samples of all the forage fields showed Cu mean values concentration ranged from 1.94 to 0.286 mg/kg at all sites. It was maximum in Trifolium alexandrinum grown field at site 2, and minimum in Avena sativa at site 2. All the forage samples showed the mean value of Cu concentration ranged from 0.151 to 1.86 mg/kg at all sites. The concentration of Cu was maximum in Zea mays grown at site 5 and minimum in Trifolium alexandrinum at site 4. The cow blood samples showed the mean concentration of Cu ranged from 1.368 to 0.53 mg/kg at all sites. It was maximum at site 2 and minimum at site 6. Owing to the results of pollution index and transfer factors, metal content was found to be in permissible range in forages as well as animal samples.

Comparative seasonal assessment of pollution and health risks associated with heavy metals in water, sediment and Fish of Buriganga and Turag River in Dhaka City, Bangladesh

Heavy-metal pollution of surface water, sediment and fish have been seen as a major global problem, with a significant proportion of developing countries like Bangladesh. This study assessed the intensity of alarming six toxic substances (Cr, Zn, Fe, Cu, Pb and Ni) throughout the River water, sediments as well as soft tissues of three widely consumed fishes (Heteropneustes fossilis, Channa punctatus and Channa striata) obtained from two urban streams of the Buriganga and Turag in the Dhaka metropolitan. For evaluating the comparative seasonal variation of heavy-metal concentration, water and sediment samples were collected from five selected sites for two different seasons (viz. 10 from winter seasons and 10 from summer seasons). Finally, a total of 20 water samples, 20 sediment and 12 fish samples were investigated by flame atomic absorption spectroscopy (FAAS) and graphite furnace atomic absorption spectrometer (GFAAS) corrected with the Zeeman effect background correction system. The hierarchy of mean concentration of selected heavy metals in Buriganga water is found to be Fe > Cr > Ni > Zn > Cu > Pb in the winter season whereas during the summer season the order is Fe > Cr > Zn > Ni > Cu > Pb. For the River Turag, the order is Fe > Zn > Cu > Ni > Cr > Pb and Fe > Zn > Ni > Cu > Cr > Pb during winter and summer season, respectively. The level of metals studied surpassed the acceptable level of drinkable water, implying the ineptitude of drinking and cooking water from these Rivers. However, this hierarchy of heavy metals for sediments of Buriganga River changed to Fe > Cr > Ni > Zn > Cu > Pb for the winter season and Fe > Cr > Ni > Cu > Zn > Pb for the summer season. Whereas, for the Turag River, the decreasing trend of metal concentration found in sediment was Fe > Zn > Cr > Ni > Cu > Pb for both seasons. For probable human health hazard implications, contamination factor (CF) and pollution load index (PLI) were studied. The CF values revealed the low-to-moderate pollution of sediment. The PLI value above one shows the degradation of the consistency of the sediments. Fe, Ni, Pb, Cr, Zn and Cu concentrations in fish species were found to be 19.66–45.1, 0.07–12.18, 1.2–10.18, 20.18–187.07, 11.08–68.25, 2.07–10.4 mg/kg, respectively. The metals studied differed considerably among organisms and seasons. Bioconcentration factor (BCF), the daily average consumption of metal (EDI), as well as target threat quotients (THQs) for specific metal indicated that Cr and Pb are harmful in fish muscles and possible risks remain for fish consumers. The obtained concentrations of some metals are higher than the WHO/FAO’s permissible limit, suggesting that the water and fish found in these Rivers are like to be harmful to the human being. This study shows that attention should be given to the risk assessment for heavy metals in these Rivers.

Investigation of metal concentrations in roadside soils and plants in urban areas of Amritsar, Punjab, India, under different traffic densities

Vehicular emissions containing traces of different heavy metals are known to cause significant contamination of roadside soils and plants. The present study was conducted to investigate the heavy metal concentrations in roadside soil and plant samples (Alstonia scholaris, Nerium oleander, Tabernaemontana divaricata, and Thevetia peruviana) collected from urban areas of Amritsar city of Punjab, India, under different traffic densities. The soil and plant samples were collected in pre- and post-monsoon seasons from seven roadside sites under varying levels of traffic density and analyzed for four heavy metals (Cd, Cu, Pb, and Zn). In addition to that, total protein and carotenoid contents in plant samples were also determined. pH and electrical conductivity analysis of roadside soil samples revealed slight to strongly alkaline and non-saline nature of soil. Significant reduction in contents of total proteins and carotenoids was observed in plants collected from sites with moderate to high traffic density. The trend of heavy metal contents in plants and their corresponding soil samples was observed to be Zn > Cu > Pb > Cd for both the seasons. Index of geo-accumulation indicated moderate contamination of soil with metals analyzed, while bio-accumulation factor (BAF) showed both absorption and accumulation of metals in plants under study. The study revealed significant contamination of roadside soil and plants of Amritsar city which was linked to vehicular emissions posing potential risk to human health.

Concentrations of selected trace elements in surface soils near crossroads in the city of Bratislava (the Slovak Republic)

It is well known that road transport emits various trace elements into the environment, which are deposited in soils in the vicinity of roads, so-called roadside soils, and thus contributes to the deterioration of their chemical state. The aim of this work was to determine concentrations of some metals and metalloids (arsenic (As), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), antimony (Sb), vanadium (V), and zinc (Zn)) in soils from crossroads with traffic signals, which are characterized by deceleration of vehicles and increased emissions of elements related mainly to brake and tyre wear. The results confirmed a moderate enrichment of soils with Cu, Pb, and Zn (enrichment factor (EF) values > 2) and significant enrichment for Sb (EF > 5), while the other elements showed no or minimal enrichment. The age of crossroads proved to have a positive influence on the accumulation of some elements in soils with the largest differences for Cu, Fe, Pb, Sb, and Zn (p < 0.001). Traffic volumes expressed as the average daily traffic intensity (ADTI) also positively influenced soil concentrations of Cr, Cu, Pb, Sb, and Zn, while distance to the crossroad had a significant negative effect on the soil concentration of Cu, Sb, and Zn (p < 0.001). The stable isotopic ratios of Pb, ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁶Pb, ranging from 1.1414 to 1.2046 and from 2.0375 to 2.1246, respectively, pointed to the mixed natural-anthropic origin of Pb in the soils of crossroads with a visible contribution of traffic-related sources. Based on the above findings combined with covariance among the studied elements using statistical methods applied to compositionally transformed data, it was possible to show that Cu, Pb, Sb, and Zn clearly originated from road traffic.

Assessment of Cu, Pb and Zn content in selected species of grasses and in the soil of the roadside embankment

It was assumed in the study that heavy metals occurring in soils and the air accumulate in grasses constituting the main species used in the turfing of soil in road verges and embankments along traffic routes and in other parts of urbanized areas. The aim of the present study was to assess the bioaccumulation of Cu, Pb, and Zn in three selected lawn cultivars of five grass species and in the soil of the roadside green belt in terms of soil properties and heavy metal uptake by plants in the aspect of determining their usefulness in protecting the soils from contamination caused by motor vehicle traffic. Samples of the plant material and soil were collected for chemical analysis in the autumn of 2018 (October) on the embankment along National Road No. 17 between Piaski and Łopiennik (Poland), where 15 lawn cultivars of five grass species had been sown 2 years earlier. During the study, Cu, Pb, and Zn levels were determined in the aboveground biomass of the grasses under study and in the soil beneath these grasses (the 0-20 cm layer). All the grass species under study can thus be regarded as accumulators of Cu and Zn because the levels of these elements in the aboveground biomass of the grasses were higher than in the soil beneath these grasses. The present study demonstrates that the grasses can accumulate a large amount of Cu and Zn from soils and transfer it to the aboveground biomass. Tested species of grasses are not a higher bioaccumulators for Pb. The best grass species for the sowing of roadsides embankment, with the highest BCF values for the studied metals, is Lolium perenne (Taya variety).

Distribution and Behaviour of Some Trace Elements as a Function of Apple Varieties in Northeastern Romania

The levels and distribution of 9 trace elements in apples from two orchards in north-east (NE) Romania were measured by means of Atomic Absorption Spectroscopy (AAS) on 42 samples of 9 different apple varieties, with average content ranges of 0.909–4.458 mg·kg⁻¹ Zn, 0.055–0.409 mg·kg⁻¹ Cu, 0.700–2.476 mg·kg⁻¹ Fe, 0.328–0.695 mg·kg⁻¹ Mn, 0.054–0.257 mg·kg⁻¹ Ni, 0.005–0.101 mg·kg⁻¹ Cr, 0.027–0.420 mg·kg⁻¹ Co, 0.413–1.149 mg·kg⁻¹ Pb, and 0.025–0.127 mg·kg⁻¹ Cd. For some apple varieties, Pb contents are 2 times higher than the maximum contents allowed according to national standards, Cd contents are 6 times higher, and in some cases Zn contents also exceed the national threshold, showing preferential accumulation on specific apple varieties. Whilst some research has been carried out on trace element distribution in apples, this study assessed the areal distribution of toxic trace elements in connection to the adjacent roads. The first apple orchard is located near a county road, with reduced car traffic, while the second orchard shares its southern limit with a high-volume traffic road (E583). The results point towards a proportional increase of Pb and, to some extent, of Cd in the samples close to the E583 road in contrast with the other orchard, where no such observation derived. Along the areal distribution of the selected elements, the preferential accumulation of dietary recommended trace elements in different apple varieties was assessed. In matters of daily nutrients content in trace elements, the best sources of Fe, Cu, and Zn in terms of apple varieties are Golden Delicious, Jonathan, and Kaltherer Böhmer.

Monitoring and assessment of cadmium, lead, zinc and copper concentrations in arable roadside soils in terms of different traffic conditions

Quantification of the contributions from traffic source to arable roadside soil heavy metal loadings is a challenge. The contribution depends on: traffic intensity, road type and distance from the road. At a field scale (3.9 ha), 720 topsoil samples were taken. The aim of the study was to monitor and assess the impact of regional/local roads with various conditions of traffic and period of use on the distribution of Cd, Zn, Pb and Cu in the arable roadside topsoil in their vicinity. PCA indicated the occurrence of two main gradients of 11 environmental elements influencing the distribution of heavy metals in the soils of the neighbouring land. The first gradient was associated mainly with the distance from the edge of the road. The second gradient was associated with the degree of contamination of the soils and with the road type, defined by the traffic volume and period of being use. Anova reviled lack of influence of the factors for Cu contents. Unlike Cu, for Cd, Pb and Zn, the significant impact was observed for both factors and interactions between them. The concentrations of Cd, Pb and Zn, regardless of the distance from the road were 0.21-0.58 mg Cd kg^-1 d.m., 13.60-41.96 mg Pb kg^-1 d.m. and 40.31-63.97 mg Zn kg^-1 d.m. In case of increasing distance from the road, generally the contents of Pb, Zn and Cd contents were decreasing. However, only in the case the oldest and carrying the highest traffic road was a clear, statistically significant differences noted for following distances from the road on the content of Cd, Pb and Zn. Analysis of spread gave trend curves, for Pb, Cd and Zn they were parabolas. The curves let reduce sapling distances to 65 m, 45 and 47 m for Cd, Pb and Zn, respectively.

Quantifying factors related to urban metal contamination in vegetable garden soils of the west and north of Melbourne, Australia

Vegetable gardens in cities provide communities with fresh vegetables but also may contribute towards public exposure to metals present in soil from historical pollution. Contamination of some Melbourne garden soils with Pb (range 12.9-773 mg kg^-1 in soil) was found with some soils exceeding the Australian human health screening criteria for residential land use of 300 mg kg^-1. Cadmium concentrations (0.12-1.04 mg kg^-1) were above the ambient background soil concentrations of <1 mg kg^-1. Nickel concentrations (7.6-40.5 mg kg^-1) and Cr (11.6-49.4 mg kg^-1) were within the range of expected ambient background concentrations. Distance from the nearest arterial road, house age and the likely use of lead-based paints were the main factors explaining approximately 75% of soil Pb variability in garden soils. Metal concentrations in garden soils of wooden houses were found to be significantly higher than the garden soil of brick and concrete houses (Pb (p < 0.0001)) and Cd (p < 0.001)). Significant correlations were found between backyard garden soil metal concentration and house age for Pb (R² = 0.83, p < 0.0001) and Cd (R² = 0.40, p < 0.0002) and the distance from arterial roads for Pb (R² = 0.38, p < 0.002), while Cr and Ni are related to soil characteristics cation exchange capacity, organic matter, and pH. Vegetable garden with elevated Pb and Cd had recognizable risk factors such as older, painted structures on adjacent houses and closer proximity to arterial roads with higher frequency traffic.

The Distribution of Trace Metals in Roadside Agricultural Soils, Thailand

Vehicle emissions have been known to cause trace metal contamination in soils. The extent of such contaminations in soils, and of the effects of traffic density and distance from highways on the concentration of trace metals in roadside agricultural soils is largely unknown. This study examined the total concentrations of common trace metals (Cd, Co, Cr, Cu, Ni, Pb, V, and Zn) in roadside agricultural soils from Thailand with diverse traffic densities (approximately 30–200 million vehicles/kilometer/year), roadside distances (0, 10, 20, 50, and 100 m from the road edge), and crops (rice, maize, and sugarcane). Cadmium, Cu, Pb, and Zn concentrations significantly decreased with increasing distance away from the roads (p < 0.05). However, the concentrations of these metals were not correlated with traffic density, probably due to extensive road maintenance and expansion. The contamination factor demonstrated that the road edge soils were moderately- to highly-polluted with Cd, Cu, Pb, and Zn. The safest distance to minimize metal pollution for agricultural production is proposed to be greater than 10 m away from the road edge.

Trace elements in soil-vegetables interface: Translocation, bioaccumulation, toxicity and amelioration - A review

The contamination of soil and vegetables with trace elements is one of the most severe ecological problems in developing industrialized countries. Trace elements are released into the environment from natural and anthropogenic activities and accumulated in soil and vegetables through various pathways which ultimately affects the human health. The present review aimed at 1) discussing the anthropogenic sources in detail, 2) describing the bioaccumulation, absorption, and transportation of trace elements, 3) exploring the options to reduce the health risk due to consumption of contaminated vegetables, 4) identifying the research and policy gaps related to soil and vegetables contamination with trace elements. Besides these objectives, the present review also detailed the several factors which affect the rate of accumulation, toxicity mechanism, and effects of trace elements on vegetables and humans. Various toxicity indices for health risk assessment have also been described. It is suggested to evaluate the trace metals concentration in irrigation water and soil prior to plant the vegetable to minimize the possible contamination.

Investigating the Role of Wind in the Dispersion of Heavy Metals Around Mines in Arid Regions (a Case Study from Kushk Pb-Zn Mine, Bafgh, Iran)

The Kushk Pb-Zn mine is located in Central Iran and it has been in operation for the last 75 years. To investigate the role of wind dispersion of heavy metal pollutants from the mine area, dust samples were collected during 1 year and topsoil samples were collected around the mine. Results showed that the topsoil is polluted with Pb and Zn to about 1500 m away from the mine. It was also found that there was not a significant difference between the metal concentrations in topsoil and dust samples. The Pb and Zn concentrations in the dust samples exceeded 200 mg kg^-1 and their lateral dispersion via wind was estimated to be about 4 km away from the mine. It has been shown that a combination of mining activities and mechanical dispersion via water and wind have caused lateral movement of heavy metals in this area.

Polycyclic Aromatic Hydrocarbons Content in Contaminated Forest Soils with Different Humus Types

The aim of the study was to determine polycyclic aromatic hydrocarbon (PAH) content in different forest humus types. The investigation was carried out in Chrzanów Forest District in southern Poland. Twenty research plots with different humus types (mor and mull) were selected. The samples for analysis were taken after litter horizons removing from a depth of 0-10 cm (from the Of- and Oh-horizon total or A-horizon). pH, organic carbon and total nitrogen content, base cations, acidity, and heavy metal content were determined. In the natural moisture state, the activity of dehydrogenase was determined. The study included the determination of PAH content. The conducted research confirms strong contamination of study soil by PAHs and heavy metals. Our experiment provided evidence that different forest humus types accumulate different PAH amounts. The highest content of PAHs and heavy metals was recorded in mor humus type. The content of PAHs in forest humus horizon depends on the content and quality of soil organic matter. Weaker degradation of hydrocarbons is associated with lower biological activity of soils. The mull humus type showed lower content of PAHs and at the same time the highest biological activity confirmed by high dehydrogenase activity.

Local plant responses to global problems: Dactylis glomerata responses to different traffic pollutants on roadsides

The growing number of road vehicles is a major source of regional and global atmospheric pollution increasing concentrations of CO₂ in the air, and levels of metals in air and soil. Nevertheless, the effects of these pollutants on plants growing at roadsides are poorly documented. We carried out an observational study of unmanipulated plants growing by the road, to identify the morpho-physiological responses in a perennial grass Dactylis glomerata. Firstly, we wanted to know the general effect of traffic intensity and ambient CO₂ and its interactions on different plant traits. Accordingly, we analyzed the photosynthetic response by field A/Ci Response Curves, SLA, pigment pools, foliar nitrogen, carbohydrates and morphological traits in plants at three distances to the road. Secondly, we wanted to know if Dactylis glomerata plants can accumulate metals present on the roadside (Pb, Zn, Cu, and Sr) in their tissues and rhizosphere, and the effect of these metals on morphological traits. The MANCOVA whole model results shown: 1) a significant effect of road ambient CO₂ concentration on morphological traits (not affected by traffic intensity, P _{interaction CO2 x traffic intensity}>0.05), that was mainly driven by a significant negative relationship between the inflorescence number and ambient CO₂; 2) a positive and significant relationship between ambient CO₂ and the starch content in leaves (unaffected by traffic intensity); 3) a reduction in J_max (electron transport rate) at high traffic intensity. These lines of evidences suggest a decreased photosynthetic capacity due to high traffic intensity and high levels of ambient CO₂. In addition, Pb, Cu, Zn and Sr were detected in Dactylis glomerata tissues, and Cu accumulated in roots. Finally, we observed that Dactylis glomerata individuals growing at the roadside under high levels of CO₂ and in the presence of metal pollutants, reduced their production of inflorescences.

Water Quality in Surface Water: A Preliminary Assessment of Heavy Metal Contamination of the Mashavera River, Georgia

Water quality contamination by heavy metal pollution has severe effects on public health. In the Mashavera River Basin, an important agricultural area for the national food system in Georgia (e.g., vegetable, dairy and wine production), water contamination has multiple influences on the regional and country-wide health. With new industrial activities in the region, sediment extraction, and discharge of untreated wastewater into the river, its tributaries and irrigation canals, a comprehensive study of water quality was greatly needed. This study examined sediment and water samples from 17 sampling sites in the Mashavera River Basin during the high and low precipitation seasons. The results were characterized utilizing the Geo-accumulation Index (I_geo), Enrichment Factor (EF), Pollution Load index (PLI), Contamination Factor (CF) and Metal Index (MI). According to the CFs, Cu > Cd > Zn > Pb > Fe > Mn > Ni > Cr > Hg is the descending order for the content of all observed heavy metals in sediments collected in both seasons. Fe and As were additionally examined in water samples. Overall, As, Cd and Pb, all highly toxic elements, were found in high concentrations in downstream sample sites. According to these results, comprehensive monitoring with narrow intervals between sampling dates, more sample sites along all waterways, and proximate observation of multiple trace metal elements are highly recommended. Moreover, as the part of the water quality governance system, an immediate and sustainable collective action by all stakeholders to control the pollution level is highly recommended, as this issue is linked to the security of the national food system and poses a local public health risk.

Green garden snail, Cantareus apertus, as biomonitor and sentinel for integrative metal pollution assessment in roadside soils

The present investigation was conceived to study, in a small scale field study, the potential of the green garden snail, Cantareus apertus, as biomonitor and sentinel for integrative metal pollution assessment in soils. For this purpose, we investigated the association between the trace metal (Cd, Pb, As, Fe, Cr, Cu, Ni, and Zn) concentrations in soil, plants (Trifolium repens), and C. apertus depending on the distance (20, 150, and 700 m) from a main roadside in Tunisia as well as between metal concentrations and biomarkers of oxidative stress, oxidative damage, and neurotoxicity in C. apertus. Results revealed a clear association between the concentration of metals such as Ni, Cu, and Zn in snail digestive gland, both amongst them and with oxidative stress and neurotoxicity biomarkers recorded in the same organ. Interestingly, Ni, Pb, and Zn occurred at the highest concentration in soil, plant, and snails and the association appeared related to the immediacy of the roadside and the concentration of these three metals tended to decrease with distance from the roadside in the soil-plant-snail system. Conversely, Cd and Cu were bioaccumulated in plants and snails but their concentrations in soil were not high and did not show a decline in concentration with distance from the roadside. After PCA analysis, PC-01 (56% of the variance) represented metal bioaccumulation and associated toxic effects in snails in the presence of high levels of metal pollution (nearby the roadside) while PC-02 (35% of the variance) represented stress induced by moderate levels of metal pollution (at intermediate distances from the roadside). The four studied sites were clearly discriminated one from each other, depending on how they are affected by traffic pollution. In summary, this field study reveals that (a) C. apertus can be used as biomonitor for metal pollution in roadside soils and as sentinel for pollution effects assessment based on biochemical biomarkers; and (b) that oxidative stress and neurotoxicity biomarkers endow with a powerful biological tool for metal pollution biomonitoring in soils, especially in combination with chemical analysis of the soil-plant-snail transfer system. Moreover, this study provides some baseline data for future impact assessments concerning trace metal pollution in Tunisia.

Evaluation of the content of Zn, Cu, Ni and Pb as well as the enzymatic activity of forest soils exposed to the effect of road traffic pollution

The paper evaluates the contents of total forms of selected heavy metals (Zn, Cu, Ni and Pb) as well as the activity of catalase (CAT), dehydrogenases (DEH), alkaline phosphatase (AlP) and acid phosphatase (AcP) in mineral surface horizons of forest soils exposed to the effect of road traffic pollutions. The sampling locations (n = 24) were determined in the area covered by the Szubin Forest along the exit road from Bydgoszcz to Poznań (provincial road no. 223). Soil was sampled 25 m away from the traffic lane, from two depths, 5-20 cm (humus horizons) and 20-50 cm (eluvial horizons). The contents of the heavy metals analysed were in the order of Pb > Zn > Cu > Ni. Despite intensive road traffic, with the Integrated Pollution Index (IPI) calculated, there was found a low pollution with nickel, average with zinc and copper and high with lead only. However, under the Regulation of the Minister of Environment, heavy metal values recorded allow for classifying the soils analysed as soils unpolluted with those metals. In the soil samples analysed, there were found significant positive dependencies between the content of clay fraction and zinc (r = 0.455; P < 0.05) and copper (r = 0.430; P < 0.05). With the enzyme activity results, values of the soil resistance index (RS) were calculated. The enzymes analysed were classified in the following decreasing order in terms of their resistance to traffic pollution: catalase > acid phosphatase > alkaline phosphatase > dehydrogenases (humus horizons) and catalase > dehydrogenases > alkaline phosphatase > acid phosphatase (eluvial horizons). Organic carbon showed a significant positive correlation with the activities of alkaline (r = 0.668; P < 0.05) and acid phosphatase (r = 0.668; P < 0.05) however not with catalase and dehydrogenases.

Phytoextraction of rare earth elements in herbaceous plant species growing close to roads

The aim of study was to determine the phytoextraction of rare earth elements (REEs) to roots, stems and leaves of five herbaceous plant species (Achillea millefolium L., Artemisia vulgaris L., Papaver rhoeas L., Taraxacum officinale AND Tripleurospermum inodorum), growing in four areas located in close proximity to a road with varied traffic intensity. Additionally, the relationship between road traffic intensity, REE concentration in soil and the content of these elements in plant organs was estimated. A. vulgaris and P. rhoeas were able to effectively transport REEs in their leaves, independently of area collection. The highest content of REEs was observed in P. rhoeas leaves and T. inodorum roots. Generally, HREEs were accumulated in P. rhoeas roots and leaves and also in the stems of T. inodorum and T. officinale, whereas LREEs were accumulated in T. inodorum roots and T. officinale stems. It is worth underlining that there was a clear relationship between road traffic intensity and REE, HREE and LREE concentration in soil. No positive correlation was found between the concentration of these elements in soil and their content in plants, with the exception of T. officinale. An effective transport of REEs from the root system to leaves was observed, what points to the possible ability of some of the tested plant species to remove REEs from soils near roads.

Organic and Inorganic Pollutant Concentrations Suggest Anthropogenic Contamination of Soils Along the Manali-Leh Highway, Northwestern Himalaya, India

Most studies on roadside soil pollution have been performed in areas where petrol is the main fuel. Very little work has been conducted in regions where diesel predominates. We collected soil samples from four sites that span a precipitation gradient along the Manali-Leh Highway in northwestern Himalaya, India. This road traverses rough terrain and most of the vehicles that travel along it are diesel-driven. At each site, we collected samples at incremental distances from the highway (0, 2, 5, 10, 20, and 150 m), and at each distance we collected samples from three depths (3, 9, and 15 cm). We assessed the concentrations of 10 heavy metals (Al, Fe, Cr, Cu, Pb, Ni, Co, Zn, V, and Ba), total sulphur, and total organic carbon (TOC) at each distance, and we measured the concentration of 16 polycyclic aromatic hydrocarbons (PAHs) at 2 m from the highway. Overall, we found that metal concentrations are low and there is no relationship between concentrations and distance from the highway, or depth within the soil profile. Sulphur concentrations, on the other hand, are high in roadside soils and there is a negative relationship between concentration and distance from the highway. PAH concentrations are low, but the proportion of different ringed species suggests that their source is anthropogenic. Correlations between TOC and the various pollutants further suggest that diesel vehicles and potentially biomass combustion are starting to affect the roadside environment in remote northwestern India. We suggest that pollutant concentrations be regularly monitored.

Traffic-related trace elements in soils along six highway segments on the Tibetan Plateau: Influence factors and spatial variation

The accumulation of traffic-related trace elements in soil as the result of anthropogenic activities raises serious concerns about environmental pollution and public health. Traffic is the main source of trace elements in roadside soil on the Tibetan Plateau, an area otherwise devoid of industrial emissions. Indeed, the rapid development of tourism and transportation in this region means it is becoming increasingly important to identify the accumulation levels, influence distance, spatial distribution, and other relevant factors influencing trace elements. In this study, 229 soil samples along six segments of the major transportation routes on the Tibetan Plateau (highways G214, S308, and G109), were collected for analysis of eight trace elements (Cr, Co, Ni, As, Cu, Zn, Cd, and Pb). The results of statistical analyses showed that of the eight trace elements in soils, Cu, Zn, Cd, and Pb were primarily derived from traffic. The relationship between the trace element accumulation levels and the distance from the roadside followed an exponential decline, with the exception of Segment 3, the only unpaved gravel road studied. In addition, the distance of influence from the roadside varied by trace element and segment, ranging from 16m to 144m. Background values for each segment were different because of soil heterogeneity, while a number of other potential influencing factors (including traffic volume, road surface material, roadside distance, land cover, terrain, and altitude) all had significant effects on trace-element concentrations. Overall, however, concentrations along most of the road segments investigated were at, or below, levels defined as low on the Nemero Synthesis index.

Air pollution monitoring using emission inventories combined with the moss bag approach

Inventory of emission sources and biomonitoring with moss transplants are two different methods to evaluate air pollution. In this study, for the first time, both these approaches were simultaneously applied in five municipalities in Campania (southern Italy), deserving attention for health-oriented interventions as part of a National Interest Priority Site. The pollutants covered by the inventory were CO, NOx, particulate matter (PM10), volatile organic compounds (VOCs), and some heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, Se, and Zn). The biomonitoring survey was based on the use of the devitalized moss Hypnum cupressiforme transplanted into bags, following a harmonized protocol. The exposure covered 40 agricultural and urban/residential sites, with half of them located in proximity to roads. The pollutants monitored were Al, As, Cd, Cr, Cu, Fe, Hg, Ni, Pb, Se, and Zn, as well as total polycyclic aromatic hydrocarbons (PAHs) only in five sites. Using the emission inventory approach, high emission loads were detected for all the major air pollutants and the following heavy metals: Cr, Cu, Ni, Pb and Zn, over the entire study area. Arsenic, Pb, and Zn were the elements most accumulated by moss. Total PAH postexposure contents were higher than the preexposure values (~20-50% of initial value). Moss uptakes did not differ substantially among municipalities or within exposure sites. In the five municipalities, a similar spatial pattern was evidenced for Pb by emission inventory and moss accumulation. Both approaches indicated the same most polluted municipality, suggesting their combined use as a valuable resource to reveal contaminants that are not routinely monitored.

Level and Contamination Assessment of Soil along an Expressway in an Ecologically Valuable Area in Central Poland

Express roads are a potential source of heavy metal contamination in the surrounding environment. The Warsaw Expressway (E30) is one of the busiest roads in the capital of Poland and cuts through the ecologically valuable area (Mazowiecki Natural Landscape Park). Soil samples were collected at distances of 0.5, 4.5 and 25 m from the expressway. The concentrations of cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) were determined in the soils by the flame atomic absorption spectrometry method (FAAS). Soils located in the direct proximity of the analyzed stretch of road were found to have the highest values of pH and electrical conductivity (EC), which decreased along with an increase in the distance from the expressway. The contents of Cd, Cu and Zn were found to be higher than Polish national averages, whereas the average values of Ni and Pb were not exceeded. The pollution level was estimated based on the geo-accumulation index (I_geo), and the pollution index (PI). The results of I_geo and PI indexes revealed the following orders: Cu < Zn < Ni < Cd < Pb and Cu < Ni < Cd < Zn < Pb, and comparison with geochemical background values showed higher concentration of zinc, lead and cadmium.

Assessment of ecological and human health risks of heavy metal contamination in agriculture soils disturbed by pipeline construction

The construction of large-scale infrastructures such as nature gas/oil pipelines involves extensive disturbance to regional ecosystems. Few studies have documented the soil degradation and heavy metal contamination caused by pipeline construction. In this study, chromium (Cr), cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) levels were evaluated using Index of Geo-accumulation (I_geo) and Potential Ecological Risk Index (RI) values, and human health risk assessments were used to elucidate the level and spatial variation of heavy metal pollution risks. The results showed that the impact zone of pipeline installation on soil heavy metal contamination was restricted to pipeline right-of-way (RoW), which had higher I_geo of Cd, Cu, Ni and Pb than that of 20 m and 50 m. RI showed a declining tendency in different zones as follows: trench > working zone > piling area > 20 m > 50 m. Pipeline RoW resulted in higher human health risks than that of 20 m and 50 m, and children were more susceptible to non-carcinogenic hazard risk. Cluster analysis showed that Cu, Ni, Pb and Cd had similar sources, drawing attention to the anthropogenic activity. The findings in this study should help better understand the type, degree, scope and sources of heavy metal pollution from pipeline construction to reduce pollutant emissions, and are helpful in providing a scientific basis for future risk management.

Traffic-related trace element accumulation in roadside soils and wild grasses in the Qinghai-Tibet Plateau, China

This research examines traffic-source trace elements accumulations and distributions in roadside soils and wild grasses in the Qinghai-Tibet Plateau. A total of 100 soil samples and 100 grass samples including Achnatherum splendens, Anaphalis nepalensis, Artemisia sphaerocephala, Carex moorcroftii, Iris lacteal, Kobresia myosuroides, Oreosolen wattii, Oxytropis ochrocephala and Stellera chamaejasme were collected at 100 sites from different road segments. The contents of metals and metalloids, including Cu, Zn, Cd, Pb, Cr, Co, Ni and As, in the soil and grass samples were analyzed using ICP-MS. The total mean concentrations of the eight trace elements in soils are Cu (22.84 mg/kg), Zn (100.56 mg/kg), Cd (0.28 mg/kg), Pb (28.75 mg/kg), Cr (36.82 mg/kg), Co (10.24 mg/kg), Ni (32.44 mg/kg) and As (21.43 mg/kg), while in grasses are Cu (9.85 mg/kg), Zn (31.47 mg/kg), Cd (0.05 mg/kg), Pb (2.06 mg/kg), Cr (14.16 mg/kg), Co (0.55 mg/kg), Ni (4.03 mg/kg) and As (1.33 mg/kg). The metal and metalloid concentrations in the nine grass species were all below the critical values of hyperaccumulators. The mean values and Multivariate Analysis of Variance (MANOVA) results indicate that: (1) the concentrations of the trace elements in the soils are higher than those in the grasses, (2) the concentrations of Cu, Zn, Cd, Pb in the soils decrease as the roadside distance increases, (3) the concentrations of trace elements in the grasses are the highest at 10 m from the road edge, (4) the higher the traffic volume, the higher the concentrations of the trace elements in the roadside soils and grasses, and (5) when the land cover is meadow, the lower the sand content in the soil, the lower the trace element concentrations. With a trace element’s bioavailability represented by its transfer factor (TF) from the soil to the grass, the TFs of the eight trace elements are not in the same orders for different grass species.

Accumulations of heavy metals in roadside soils close to zhaling, eling and nam co lakes in the tibetan plateau

Concentrations of four typical heavy metals (Cu; Zn; Cd and Pb) in roadside soils close to three lakes in the Tibetan Plateau were investigated in this study. The hierarchical tree-based regression method was applied to classify concentrations of the heavy metals and analyze their potential influencing factors. It was found that the Tibetan Plateau meadow soils with higher content of sand lead to higher concentrations of Cu; Zn and Pb. The concentrations of Cd and Pb increase with road traffic volume; and for the road segments with higher traffic volume; the Cd and Pb concentrations significantly decrease with the roadside distance. Additionally; the concentrations of Zn and Pb increase as the altitude of sampling site increases. Furthermore; the Hakanson potential ecological risk index method was used to assess the contamination degree of the heavy metals for the study regions. The results show that accumulations of Cu; Zn and Pb in roadside soils remain an unpolluted level at all sites. However; the Cd indices in the regions with higher traffic volume have reached a strong potential ecological risk level; and some spots with peak concentrations have even been severely polluted due to traffic activities.

Relationships between heavy metal concentrations in roadside topsoil and distance to road edge based on field observations in the Qinghai-Tibet Plateau, China

This study investigated the spatial distribution of copper (Cu), zinc (Zn), cadmium (Cd), lead (Pb), chromium (Cr), cobalt (Co), nickel (Ni) and arsenic (As) in roadside topsoil in the Qinghai-Tibet Plateau and evaluated the potential environmental risks of these roadside heavy metals due to traffic emissions. A total of 120 topsoil samples were collected along five road segments in the Qinghai-Tibet Plateau. The nonlinear regression method was used to formulize the relationship between the metal concentrations in roadside soils and roadside distance. The Hakanson potential ecological risk index method was applied to assess the degrees of heavy metal contaminations. The regression results showed that both of the heavy metals’ concentrations and their ecological risk indices decreased exponentially with the increase of roadside distance. The large R square values of the regression models indicate that the exponential regression method can suitably describe the relationship between heavy metal accumulation and roadside distance. For the entire study region, there was a moderate level of potential ecological risk within a 10 m roadside distance. However, Cd was the only prominent heavy metal which posed potential hazard to the local soil ecosystem. Overall, the rank of risk contribution to the local environments among the eight heavy metals was Cd > As > Ni > Pb > Cu > Co > Zn > Cr. Considering that Cd is a more hazardous heavy metal than other elements for public health, the local government should pay special attention to this traffic-related environmental issue.

Relationship between heavy metal concentrations in soils and grasses of roadside farmland in Nepal

Transportation activities can contribute to accumulation of heavy metals in roadside soil and grass, which could potentially compromise public health and the environment if the roadways cross farmland areas. Particularly, heavy metals may enter the food chain as a result of their uptake by roadside edible grasses. This research was conducted to investigate heavy metal (Cu, Zn, Cd, and Pb) concentrations in roadside farmland soils and corresponding grasses around Kathmandu, Nepal. Four factors were considered for the experimental design, including sample type, sampling location, roadside distance, and tree protection. A total of 60 grass samples and 60 topsoil samples were collected under dry weather conditions. The Multivariate Analysis of Variance (MANOVA) results indicate that the concentrations of Cu, Zn, and Pb in the soil samples are significantly higher than those in the grass samples; the concentrations of Cu and Pb in the suburban roadside farmland are higher than those in the rural mountainous roadside farmland; and the concentrations of Cu and Zn at the sampling locations with roadside trees are significantly lower than those without tree protection. The analysis of transfer factor, which is calculated as the ratio of heavy-metal concentrations in grass to those in the corresponding soil, indicates that the uptake capabilities of heavy metals from soil to grass is in the order of Zn > Cu > Pb. Additionally, it is found that as the soils’ heavy-metal concentrations increase, the capability of heavy-metal transfer to the grass decreases, and this relationship can be characterized by an exponential regression model.